August 14, 2023 • 34 mins
Cases of dengue are increasing globally, with large-scale outbreaks across Nepal, Peru, Bangladesh, Brazil and Argentina to name a few. This epidsode provides an overview for expedition medics, humanitarians, overlanders, trip leaders, safety staff, film crews and disaster response teams, including key risks, prevention strategies, signs, symptoms, DDx, diagnostic tools and field treatment. From water treatment and fogging to vaccines and natural repellent...this show is all about dengue prevention.
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Episode Transcript
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(00:38):
Welcome to the Red Mead Podcast RescueExpedition and Disaster Medicine, where we provide
a platform for healthcare professionals working inor aspiring to join rescue expedition and disaster
response teams, a platform to shareinformation, advice and opportunities and connect like
minded Red med individuals in our community. Good afternoon, and welcome to the
(01:00):
Red Mead Podcast Rescue Expedition and DisasterMedicine. As usual, this podcast is
sponsored by ss Coffee coffee which wesell to fund medical missions for underserved communities
in Guatemala. It was fantastic tospeak to a lot of you out in
the Wilderness Medical Society conference over inSpokane last month, and a lot of
(01:23):
you expressed interest in coming down todo the Red Mead course and specifically to
help out on the medical missions.So thanks for your interest, thanks for
buying the coffee, and more dealswill be coming out soon about that medical
mission next May. In addition tothe coffee, the proceeds from my book
Denghy, A Guide to Prevention,Diagnosis and Field Treatment also go to support
(01:49):
the medical missions and our communities downin southwest Guatemala Today. As the title
suggests, I'd like to talk aboutdenghy. The podcast might be useful for
risk managers, expedition leaders, expeditionmedics, humanitarians, anybody traveling to any
(02:10):
of the over one hundred countries aroundthe world where Denghy's endemic at the moment,
and it might be useful to createawareness to complement your risk strategy or
your risk mitigation strategy to prevent denghyin your team or your operation. But
why is important. Let's look atsome of my personal experiences and then look
(02:34):
at some of the serious statistics inthe literature at the moment. So aside
from being an unwelcome fedrile illness thatmight result in one of your teammates becoming
bedridden for a week or just confusinga differential diagnoses and creating chaos because of
the non specific symptoms, cases aregenerally on the rise globally as our deaths
(03:00):
from severe denghy. My own experiencethat there are three three distinct experiences that
stand out, the first being beenbedridden with fever and achy bones in a
hotel room in Nepoal following an expeditionto Everest Base camp. There was an
outbreak in Katmandu of about thirty fivethousand cases at the time. I'd been
(03:25):
bitten on a rival back from theKumbu and succumbed to all of the classics
signs and symptoms. Secondly, Iwas responsible for the mitigation of denghi whilst
on a film set in a tropicalcountry. We had a crew of eight
hundred people and we're filming on aset in the rainy season, surrounded by
(03:51):
shallow streams, ponds, pools,tires filled with water, and there was
an outbreak of dinghy at the timewhere we were shooting. So that was
a full team effort to try andmitigate the spread of denghy amongst the crew.
And then, ultimately, but mostmemorably, was following a medical mission
(04:11):
in Guatemala. We had an internationalteam of allied health professionals volunteered, plus
a lot of guys from my companySOS Medical Services, a lot of the
volunteer fire service, helping the communitywith everything from dental hygiene, water treatment
education. Ironically Mosquito born disease mitigationas well as providing primary care services.
(04:35):
They did a phenomenal job. Justas we were closing up, we just
closed the last pelican case, loadedeverything onto the back of the pickups and
the ambulances that a father walked overthe brow of the hill with his unconscious
twelve year old boy in his arms. We assessed him. He was disoriented,
(04:58):
he hadn't eaten or drank for thebest part of five to seven days.
He had no radial pulse, hypertensivegoing into shock, and on closer
inspection he had a temperature of thirtynine degrees and he had epistaxis and bleeding
from the gums, classic hemorrhagic denghy, or what is now known by the
World Health Organization as severe denghy.We gave him a bolus of fluids antipyretics
(05:24):
quickly transport him to hospital, wherehe received a blood transfusion and made a
full recovery. Thankfully. I thinkI don't think his parents realized the gravity
of it, nor did they havethe finances to get to hospital or to
buy the medications, and I thinkXavier would have probably died. Fortunately he
(05:47):
didn't. The guys that were workingwith us picked up on it quickly,
but ultimately it really sends a messagethat prevention is extremely important. As his
early recognition and treatment of dan SoDenghi is currently endemic to over one hundred
countries worldwide. In the Americas alone, there were two point five million cases
(06:10):
in the first forty weeks of lastyear. Some regions of the Americas have
had up to two hundred and fiftyone cases per hundred thousand population. Again,
in the Americas, there were threethousand, six hundred and forty five
cases of severe denghi reported, withone thousand, one hundred and thirty deaths.
(06:30):
The European CDC reports that mosquitos responsiblefor the transmission of denghi have established
themselves in thirteen new European countries.But I think more specifically this year there
have been three large scale outbreaks,or rather the back end of last year.
In Kathmandu, there were thirty fivethousand cases of denghi in the city,
(06:56):
with thirty eight confirmed deaths. InPeru this year there have been one
hundred and forty six thousand cases reportedwith two hundred and forty eight deaths.
And then more recently, in Argentinathere's been an outbreak of sixty thousand infections
and forty deaths to date. Ina recent study by the London School of
(07:17):
Hygiene and Tropical Medicine along with theUniversity of Oxford. The study results forecasted
that sixty percent of the world's populationwill be at risk of contracting DENGHI by
the year twenty eighty, driven byin part by changing weather patterns, climate
change, urbanization, and increasing populationdensity. We're likely to see DENGHI creep
(07:44):
into our missions more and more,and so we're really going to present information
about prevention, prevention, prevention,how to keep teams safe, the personal,
the team, the operational, andthe community preventative measures along with some
of the signs, symptoms, andthe treatment of DENGHI. So what is
denghy? As most of us know, it's a mosquito born febrile illness caused
(08:11):
by one of the four Denghi RNAviruses, namely denv one, two,
three, and four or dengy virusone, two, three or four.
There is reports or there are reportsin the literature of a fifth zero type
having been identified, but the literatureis scant at the moment. So we're
going to focus today on the fourcommon zero types. But ultimately it's a
(08:37):
vector borne disease spread from person toperson by infected mosquitoes transmission usually from a
bite from an infected mosquito and usuallythrough the ADS. A gypti or the
ADS albo pictus species. It ispossible, however, to contract denghi from
(09:00):
blood transfusions through unscreened blood infected withdenghy, and this might pose a risk
two teams operating far forward that areconsidering utilizing walking blood banks and using unscreened
donors, or if the donors areoperating in areas with endemic mosquito born diseases
(09:26):
formerly known as dengey fever and dengyhemorrhagic fever. In two thousand and nine,
the World Health Organization reclassified the termsand the new terms are now dengy
and severe denghy. It's useful tounderstand when we're traveling what the life cycle
of the mosquito is and the elementsor components that they require to survive,
(09:50):
thrive, and continue to infect people. Ultimately, the Aides albapictus and the
Aides are gypti mosquito required two componentsshallow water in which to lay their eggs
and invertebrate blood, which is howthey feed and how they transmit the disease.
(10:11):
So unlike other species of mosquitoes thatprefer deeper, nutrient rich water.
The ads mosquito preverse shallow stagnant water, so shallow stagnant water sources such as
shallow pools, blocked rain gutters,water filled plant pots, pet bowls,
(10:33):
bird baths, rain barrels. Allof these kind of things are prevalent during
the rainy season and present the idealhabitat for the ads to lay their eggs
and continue the life cycle. Thingslike rivers, fast moving streams, or
deep ponds pose less of a risk, and as we mentioned, we're going
(10:58):
to see an increased likelihood of outbreaksduring the rainy season. And unlike malaria,
which is often seen in rural areas, denghi is quite often prevalent in
urban or suburban populations where there's adense human population, along with shallow water
(11:20):
sources again in the tires, ingutters, plant pots. Provides that the
perfect environment prevention prevention is key.But why is it important? Most people,
when bitten by an infected mosquito thatdeveloped denghi will be asymptomatic. Some
(11:46):
people will go on to have fabrileillness, and we'll talk about the signs
and symptoms shortly, but ultimately mostpeople are asymptomatic. Following that initial infection,
the patient will develop long term orlife long immunity to that same serotype
to the same Denghi virus, butit does not confer immunity to any of
(12:09):
the other three serotypes, and thereforesequential or subsequent infection with another serotype significantly
increases the risk of contracting severe Denghi, so prevention is key. There is
a vaccine available. There are severalvaccines in circulation and under development that are
(12:31):
approved and available in about ten totwenty countries worldwide, but they are generally
only available for at risk groups andfor anybody that has had laboratory confirmed previous
infection. The vaccine only provides protectionagainst severe Denghi for people who have already
(12:54):
had a confirmed case of Denghi.Anybody that was to be vaccinated that hasn't
had Denghi, then the vaccine mayserve as the first infection and therefore they
may be at increased risk of severeDenghy during subsequent infections. So prevention is
(13:16):
key, and preventions often through alayered approach. It's no use just putting
on insect repellent and hoping that you'llbe safe. There's a whole ecosystem of
interconnected actors that we need to consider, So the layer approach should really consider
personal prevention and protection, a teamapproach, a local environment or a camp
(13:41):
approach, and then a larger widercommunity approach. So individually, on a
personal level, we can avoid wearingshorts and t shirts avoid exposing our skin.
We can wear light colored, longsleeved clothing long trousers to prevent mosquitoes
(14:01):
landing on us and biting the skin. Utilization of repellent DET is without doubt
the best in the literature, butif anybody prefers a natural approach, then
there is good evidence to suggest thatthe natural lemon eucalyptus is the most effective
natural repellent. It's on power withDET, certainly for the first four to
(14:24):
six hours. Sleeping in mosquito netstreated with permthrine or some of the insect
repellent are very very useful to preventbites. But do consider local laws and
any local resistance to permthrine. Itmay be that permthrine is banned as it
is in Thailand, or there islocal or regional resistance, and other chemicals
(14:48):
might be recommended. Removal of standingwater sources is key. A couple of
centimeters of clean water is the perfectbreeding ground for the aides mosquito to lay
their eggs and continue the life cycleand contribute to the whole host of mosquitoes
within your operational area. So emptyout tires, empty out the water from
(15:11):
plant pots, try and remove thewater from any buckets baskets, set up
camps away from shallow ponds and pools, and then ultimately, if there's any
water sources that can't be eradicated,then you can consider treating the water with
larvicides or insect growth regulators. Acommon lava side is BTI or the BTI
(15:41):
bacteria, and I want to givethis pronunciation ago Bacillus thuringiensis israelensis or BTI
for short, ultimately to naturally occurringbacteria that comes in granules or tablets and
is added to the standing water tokill mosquito larvae. It's thought to be
(16:03):
harmless to humans and other aquatic wildlife. Simply add the correct dose of tablets
or granules. It dissolves in thewater and interferes with the growth of the
larvae and significantly reduces mosquito populations inthe area, but ultimately it should be
a two pronged attack. We're lookingat look reducing the larvae in the water
(16:29):
sources and then also the population ofadult mosquitos in the area. So space
spraying, fumigating, or fogging isuseful, and that can be done with
insecticide or adulticide to kill the adultmosquitoes in the area that often hang around
in dark shaded corners, lofts,foliage piles of duffel bags, And there's
(16:53):
two different systems really. There's thermalfoggers that use gas canisters to heat the
coils and generate the fog. They'rebest for outdoor use or very well ventilated
spaces, and then there's cold foggers, which are often battery operated or plug
into the mains and they're generally saferfor indoor use. On a more local
(17:15):
level, you've got spatial repellents suchas mosquito coils that you ignite or plug
in devices. Likewise, simple thingslike air conditioning or turning on fans will
circulate the air and potentially increase theairflow and push the mosquito away from you
so they can't land and bite youin the night if your budget allows as
(17:37):
a fantastic trap, a mosquito trapcalled the mosquito magnet. I've got no
commercial affiliation to these, but Ihave used them in tropical countries. And
this is a large device that runson propane gas and the machine essentially converts
the propane to CO two and heatand tracts and traps the mosquitoes within about
(18:03):
a two hundred foot radius, soextremely effective, but slightly more expensive than
your repellent or mosquito nets. Soit really comes down to the combination.
We need to be looking at personalprotection through insect repellents, appropriate clothing,
covering up skins, sleeping in mosquitonets. And then a team and a
(18:23):
camp approach, siting the camp awayfrom shallow water, removing standing water or
treating it daily, fogging either aroundthe camp or prior to your daily activities,
prior to patients turning up for medicalmissions, or prior to filming if
you're out on a shoot, andthen look at the broader community. If
(18:45):
there are cases of dinghy in thecommunity, and there are community members affected
or infected, and they come toworkers film extras or they come to your
clinics, then if there is amosquito population, they can bite the infected
community members, bite your team membersand continue this cycle of infection. So
(19:06):
we need to really think about howrisk mitigation should be broader and encompass the
local community. So let's get involvedwith the local leaders, look at the
local epidemiology, look at potentially educatethe local populace, or can we donate
insect repellent or mosquito nets to theat risk population. In practical terms,
(19:30):
out on the film set in atropical country during the rainy season, this
would really mean a full time jobfor the team. The team would arrive
on location about three am. They'dwalk around the set or the location emptying
pots, pans, and tires fromthe previous night's rain. They would accompany
(19:51):
the snake wrangler around to check thelocations for any unwanted guests, and then
ultimately fog the huts, bushers,drains, stores, baggage areas, kitchens,
leaving ample time for the fog orthe insector side to dissipate before the
crew arrived. Interestingly, though,rather than just eradicating mosquitoes everywhere we fogged,
(20:15):
it used to seem to drive thesnakes out into the open and we
found boa constricts and tree vipers allover the shooting location, which delayed shooting
on a couple of occasions. Soafter fogging, the team would wander around
checking the mosquito magnet traps, makingsure that it had power sufficient propane gas
(20:38):
were cited correctly based on the winddirection shooting location, so it's a fairly
dynamic job. They would have tomove the traps as the wind changed or
the shooting locations changed, and thenfollowing the daily preparation. Following the fogging
and the eradication of the standing water, the team would stay on set and
(21:00):
a company that the film crew allday offering insect repellent, clearing out any
other standing water as it rained,and then any other sources they would treat
with BTI in the background, Iwould meet with the Ministry of Health and
their delegates would collect mosquito or samplesfrom the site, taken them back to
(21:22):
the lab to determine the species,and then testing for pathogens such as denghy
zeka, chicken gunga, Japanese encephalitis, and I'm pleased to say they didn't
identify any on the location, butit was an ongoing process. So BTI
lots of questions surrounding that is itsafe for the environment, is it safe
(21:42):
for other aquatic life? And theCDC have produced a simple fact sheet on
BTI that you can access on theCDC website. But certainly if you're responsible
for fogging with insecticide, it's worthtaking a good look at them STS,
the Materials Safety data sheets, asthe insecticide can be harmful, can be
(22:04):
irritant on the skin, the eyes, the respiratory tract, so do work
with experts, have a look atthe msts and all ultimately make sure that
the fog has dissipated before the crewarrived to start work. Let's take a
look at the phases of DENGHI andsome of the signs and symptoms and the
(22:26):
diagnostic criteria. So the incubation periodsfive to seven days. Quite often patients
will develop a fever between thirty nineand forty degrees. The disease generally consists
of three phases febrile phase, thecritical stage, and the convalescent stage,
(22:51):
usually identified through two or more clinicalfindings. That the symptoms you might expect
to see could include that classic feverthirty nine to forty degrees celsius, headache,
retro orbital pain as a common complaint, muscle and joint aches, and
pains. Bone pain. Dengha usedto be called breakbone fever because of the
(23:15):
severe pain and the bones and themuscles, macular or macular popular rash and
potentially a positive tornica test. Sowhat is the tornica test? Ultimately it's
to identify pillary fragility. It's auseful clinical diagnostic method to determine a patient's
(23:36):
hemorrhagic tendency or status and potential forthrombocytopenia. And it's an accepted diagnostic tool
as cascaded by the World Health Organization. Very simple procedure. Place the blood
pressure cuff around the proximal arm,inflate the cuff to midway between the patient's
(23:57):
systolic and distolic pressure. Keep theblood pressure cuff inflated for five minutes.
At the end of the five minutes, the blood pressure cuff is removed,
and if there are more than twentypetikii in one square inch of skin,
(24:18):
that is classed as a positive testfor severe DENGHI. So there the standard
signs and we've got warning signs.Warning signs of the potential for development of
severe Denghi. So warning signs couldinclude abdominal pain, persistent vomiting, anorexia,
(24:41):
clinical fluid accumulation, and possible hypotension. Severe Denghi. We're looking at
a history of the clinical findings overthe previous two to seven days, evidence
of plasma leakage, evidence of shock, hematemesis, bloody stool bleeding, guns
(25:03):
epistaxis, respiratory distress, and alteredmental status. So how do we diagnose
it? Can we diagnose it?We're looking at the clinical findings contrasted with
the incubation period evidence of bites ina Denghy endemic area. Presenting with two
(25:29):
or more of the clinical signs,we would potentially assume it's Denghy. Likewise,
there is a PCR test for dengyor. There is an NS one
antigen test which is best done inthe first week since the onset of symptoms
and then in the second week sincethe onset of symptoms. There is an
(25:52):
IgM antibody test very similar to thecovid antigen and antibody tests. They're cheap,
disposable, and readily available in endemicregions Southeast Asia and Latin America.
So it is a non specific febrileillness, easily confused, potentially confused with
(26:18):
flu, malaria, zeka, chickengunga, COVID to name but a few.
So it's useful to keep an eyeout on the local trends. Is
there an increase in local outbreaks?Are there an increase in local cases?
Have we got appropriate mitigation measures inplace to prevent that cross infection through the
(26:38):
Denghy mosquito vector. And ultimately,if we can't diagnose it through the clinical
symptoms, the incubation period, etc. Then perhaps we can employ an NS
one antigen test or at the righttime, an antibody test, or if
you can get out from the remoteareas and get to lab that can do
(27:00):
dengy pc artists, then that mightbe useful to rule in or rule out
other pathology and specifically direct treatment.So what is the treatment for denghy?
Ultimately, there is no specific treatmentin denghy that presents with flu like symptoms.
(27:21):
The core treatment is hydration and paracetamol. Paracetamol is useful antipyretic. Likewise,
it can help with the muscle andbone aches and pains. But the
key here is to avoid drugs suchas aspirins or other non steroidal anti inflammatory
drugs due to their anticoagulant properties whichcould potentially exacerbate any bleeding. One consideration
(27:47):
when we're employing prolonged field care isto avoid exposure of the febrile patient to
mosquitoes to prevent onwards transmission to otherteam members. So if you do have
somebody in a remote area with afever and you suspect DENGHI, whilst we're
monitoring on monitoring them, checking onthem, arranging evacuation or laboratory tests,
(28:11):
that they should ideally be resting insidea mosquito net so any local mosquitoes can't
bite them and then go on tobite another team member and continue that chain
of infection. So general supportive treatmentfor DENGHI and then if there are any
signs of warning signs or severe DENGHI, then really it's employed the medical emergency
(28:33):
response plan best medicine being DIESEL andget off to the ICU so they can
be tested and provided with supportive treatmentand continual monitoring in hospital. So in
summary, I think any group travelingoverseas to not necessarily to remote areas because
DENGHI is prevalent in the urban andsuburban areas, not necessarily the deep tropical
(28:56):
rainforest. It's useful to do theresearch it's prior to heading out into these
areas, and as we always do, look at the current medical threats in
that specific area, Look at thecurrent endemic diseases, any areas of specific
outbreaks, the season, the timeof year, any specific threats that we
(29:17):
can identify through local reconnaissance, speakingto local leaders the Ministry of Health,
identifying potential filming locations, campsite locations. Are there any potential static water sources
or standing water sources that we caneradicate or if we can't, can we
identify local suppliers to provide larvicides BTI, local contractors to support with space spraying,
(29:44):
fogging or fumigation. Have we gotappropriate date inset repellent, appropriate clothing
with long sleeves, long trousers tocover up the skin, mosquito bednets to
protect ourselves. Community initiatives to lookat the wider community and perhaps how we
(30:04):
can support the community and break thelife cycle around the community and ultimately have
the community server as an extra layerof protection for our team and Likewise,
our team can serve as a layerof protection for the local community. So
that layered approach of prevention prevention preventionis really important and certainly requires a little
(30:27):
bit of forward planning rather than justturning up on the ground and trying to
cuff it through ad hoc measures.Hopefully that short introduction was useful to present
the expanding scale and scope of Denghi, the life cycle, some of the
preventative strategies and the layered approach alongwith some of the signs, symptoms and
(30:49):
diagnostic tools of Denghi, along withthe treatment and went to seek support.
Hopefully that will help you to planany future missions and mitigate any potential patients
in the future. If anyone's interestingfurther reading, there's the Denghi A Guide
to Prevention, Diagnosis and Field Treatment, which is available on Amazon and again,
(31:11):
all the proceeds from the sale ofthat book go back into our medical
missions and help us to provide mosquitonets, insect repellents and testing kits for
our communities down in southwest Guatemala.And the next medical mission will take place
in May twenty twenty four, followingthe Red Mead course. The Rex who
(31:33):
rescue Expedition disaster medicine course in Guatemalawhere we will be rafting through the jungle,
setting up jungle camps, jungle survivaltrekking a high altitude volcano and traveling
through the Land of Eternal Spring orMundo Maya. And those of you that
want to stay on for a coupleof days at the end can help out
(31:53):
with a medical mission. We're reachingout an appealing to for support from all
allied health professionals, anyone from EMTsthrough nurses, pas, paramedics, doctors,
dentists, surgeons that the communities needyour support. So if you want
to do the Red Mead course,please do get in touch. And if
(32:15):
you need to head straight home,that's cool. If you'd like to stay
in Guatemala, you can stay andjoin us for a couple of days at
the medical mission, wrapt through thejungle, get to the community and then
will be involved in everything from dentalcare, primary care, to helping the
community understand the different methods of watertreatment. And then we'll be employing different
(32:37):
workshops to help mitigate mosquito born diseases. But before that, in October November
this year, twenty twenty three,we've got the Red Mead course in the
poll, and we'll be employing theflipped classroom approach, so there's a period
of online self paced learning so thatwhen you arrive you can thoroughly enjoy the
(32:58):
Kumbo Valley and the incredible views ofthe eight thousanders as we trek towards Everest
Based Camp, doing having team discussionsaround the fire pits in the tea houses,
and then employing skills and scenario basedtraining in context in the shadow of
Everest at Everest Based Camp before goingon to do a mountaineering training day and
(33:21):
attempting a climb on a six thousandmeter peak, namely Low Boschet East at
six one hundred and nineteen meters.So all the way we'll be talking about
patient assessment, altitude sickness, hypothermia, frostbite, prolonged fieldcare, patient packaging,
helicopter safety, communications, telemedicine,medical emergency response planning, risk assessments,
(33:42):
fractures, analogies, all of thatkind of good stuff, supported by
the Red Mead faculty and our incredibleclimbing sherpas who between them have got numerous
ascent of Everest and K two.So if that sounds like fun. If
that sounds like you, do,get in touch. There are still spaces
on the October course, and ifnot, we've got the UK based course
(34:05):
coming up in February twenty twenty fourand we'll be looking at topics such as
disaster medicine, helicopter safety, mountainmedicine, search and rescue, heat,
cold bite, stings, and anawful lot of the non clinical competencies such
as mission planning, obstacle crossing,etc. Anyway, guys, thanks for
(34:25):
tuning in, thanks for listening,Thanks for your support. Wherever you are
in the world. Stay safe andhook your speak to you soon. Bye bye
Welcome to the Red Mead Podcast RescueExpedition and Disaster Medicine, where we provide
a platform for healthcare professionals working inor aspiring to join rescue expedition and disaster
response teams, a platform to shareinformation, advice and opportunities and connect like
minded Red med individuals in our community. Good afternoon, and welcome to the
(01:00):
Red Mead Podcast Rescue Expedition and DisasterMedicine. As usual, this podcast is
sponsored by ss Coffee coffee which wesell to fund medical missions for underserved communities
in Guatemala. It was fantastic tospeak to a lot of you out in
the Wilderness Medical Society conference over inSpokane last month, and a lot of
(01:23):
you expressed interest in coming down todo the Red Mead course and specifically to
help out on the medical missions.So thanks for your interest, thanks for
buying the coffee, and more dealswill be coming out soon about that medical
mission next May. In addition tothe coffee, the proceeds from my book
Denghy, A Guide to Prevention,Diagnosis and Field Treatment also go to support
(01:49):
the medical missions and our communities downin southwest Guatemala Today. As the title
suggests, I'd like to talk aboutdenghy. The podcast might be useful for
risk managers, expedition leaders, expeditionmedics, humanitarians, anybody traveling to any
(02:10):
of the over one hundred countries aroundthe world where Denghy's endemic at the moment,
and it might be useful to createawareness to complement your risk strategy or
your risk mitigation strategy to prevent denghyin your team or your operation. But
why is important. Let's look atsome of my personal experiences and then look
(02:34):
at some of the serious statistics inthe literature at the moment. So aside
from being an unwelcome fedrile illness thatmight result in one of your teammates becoming
bedridden for a week or just confusinga differential diagnoses and creating chaos because of
the non specific symptoms, cases aregenerally on the rise globally as our deaths
(03:00):
from severe denghy. My own experiencethat there are three three distinct experiences that
stand out, the first being beenbedridden with fever and achy bones in a
hotel room in Nepoal following an expeditionto Everest Base camp. There was an
outbreak in Katmandu of about thirty fivethousand cases at the time. I'd been
(03:25):
bitten on a rival back from theKumbu and succumbed to all of the classics
signs and symptoms. Secondly, Iwas responsible for the mitigation of denghi whilst
on a film set in a tropicalcountry. We had a crew of eight
hundred people and we're filming on aset in the rainy season, surrounded by
(03:51):
shallow streams, ponds, pools,tires filled with water, and there was
an outbreak of dinghy at the timewhere we were shooting. So that was
a full team effort to try andmitigate the spread of denghy amongst the crew.
And then, ultimately, but mostmemorably, was following a medical mission
(04:11):
in Guatemala. We had an internationalteam of allied health professionals volunteered, plus
a lot of guys from my companySOS Medical Services, a lot of the
volunteer fire service, helping the communitywith everything from dental hygiene, water treatment
education. Ironically Mosquito born disease mitigationas well as providing primary care services.
(04:35):
They did a phenomenal job. Justas we were closing up, we just
closed the last pelican case, loadedeverything onto the back of the pickups and
the ambulances that a father walked overthe brow of the hill with his unconscious
twelve year old boy in his arms. We assessed him. He was disoriented,
(04:58):
he hadn't eaten or drank for thebest part of five to seven days.
He had no radial pulse, hypertensivegoing into shock, and on closer
inspection he had a temperature of thirtynine degrees and he had epistaxis and bleeding
from the gums, classic hemorrhagic denghy, or what is now known by the
World Health Organization as severe denghy.We gave him a bolus of fluids antipyretics
(05:24):
quickly transport him to hospital, wherehe received a blood transfusion and made a
full recovery. Thankfully. I thinkI don't think his parents realized the gravity
of it, nor did they havethe finances to get to hospital or to
buy the medications, and I thinkXavier would have probably died. Fortunately he
(05:47):
didn't. The guys that were workingwith us picked up on it quickly,
but ultimately it really sends a messagethat prevention is extremely important. As his
early recognition and treatment of dan SoDenghi is currently endemic to over one hundred
countries worldwide. In the Americas alone, there were two point five million cases
(06:10):
in the first forty weeks of lastyear. Some regions of the Americas have
had up to two hundred and fiftyone cases per hundred thousand population. Again,
in the Americas, there were threethousand, six hundred and forty five
cases of severe denghi reported, withone thousand, one hundred and thirty deaths.
(06:30):
The European CDC reports that mosquitos responsiblefor the transmission of denghi have established
themselves in thirteen new European countries.But I think more specifically this year there
have been three large scale outbreaks,or rather the back end of last year.
In Kathmandu, there were thirty fivethousand cases of denghi in the city,
(06:56):
with thirty eight confirmed deaths. InPeru this year there have been one
hundred and forty six thousand cases reportedwith two hundred and forty eight deaths.
And then more recently, in Argentinathere's been an outbreak of sixty thousand infections
and forty deaths to date. Ina recent study by the London School of
(07:17):
Hygiene and Tropical Medicine along with theUniversity of Oxford. The study results forecasted
that sixty percent of the world's populationwill be at risk of contracting DENGHI by
the year twenty eighty, driven byin part by changing weather patterns, climate
change, urbanization, and increasing populationdensity. We're likely to see DENGHI creep
(07:44):
into our missions more and more,and so we're really going to present information
about prevention, prevention, prevention,how to keep teams safe, the personal,
the team, the operational, andthe community preventative measures along with some
of the signs, symptoms, andthe treatment of DENGHI. So what is
denghy? As most of us know, it's a mosquito born febrile illness caused
(08:11):
by one of the four Denghi RNAviruses, namely denv one, two,
three, and four or dengy virusone, two, three or four.
There is reports or there are reportsin the literature of a fifth zero type
having been identified, but the literatureis scant at the moment. So we're
going to focus today on the fourcommon zero types. But ultimately it's a
(08:37):
vector borne disease spread from person toperson by infected mosquitoes transmission usually from a
bite from an infected mosquito and usuallythrough the ADS. A gypti or the
ADS albo pictus species. It ispossible, however, to contract denghi from
(09:00):
blood transfusions through unscreened blood infected withdenghy, and this might pose a risk
two teams operating far forward that areconsidering utilizing walking blood banks and using unscreened
donors, or if the donors areoperating in areas with endemic mosquito born diseases
(09:26):
formerly known as dengey fever and dengyhemorrhagic fever. In two thousand and nine,
the World Health Organization reclassified the termsand the new terms are now dengy
and severe denghy. It's useful tounderstand when we're traveling what the life cycle
of the mosquito is and the elementsor components that they require to survive,
(09:50):
thrive, and continue to infect people. Ultimately, the Aides albapictus and the
Aides are gypti mosquito required two componentsshallow water in which to lay their eggs
and invertebrate blood, which is howthey feed and how they transmit the disease.
(10:11):
So unlike other species of mosquitoes thatprefer deeper, nutrient rich water.
The ads mosquito preverse shallow stagnant water, so shallow stagnant water sources such as
shallow pools, blocked rain gutters,water filled plant pots, pet bowls,
(10:33):
bird baths, rain barrels. Allof these kind of things are prevalent during
the rainy season and present the idealhabitat for the ads to lay their eggs
and continue the life cycle. Thingslike rivers, fast moving streams, or
deep ponds pose less of a risk, and as we mentioned, we're going
(10:58):
to see an increased likelihood of outbreaksduring the rainy season. And unlike malaria,
which is often seen in rural areas, denghi is quite often prevalent in
urban or suburban populations where there's adense human population, along with shallow water
(11:20):
sources again in the tires, ingutters, plant pots. Provides that the
perfect environment prevention prevention is key.But why is it important? Most people,
when bitten by an infected mosquito thatdeveloped denghi will be asymptomatic. Some
(11:46):
people will go on to have fabrileillness, and we'll talk about the signs
and symptoms shortly, but ultimately mostpeople are asymptomatic. Following that initial infection,
the patient will develop long term orlife long immunity to that same serotype
to the same Denghi virus, butit does not confer immunity to any of
(12:09):
the other three serotypes, and thereforesequential or subsequent infection with another serotype significantly
increases the risk of contracting severe Denghi, so prevention is key. There is
a vaccine available. There are severalvaccines in circulation and under development that are
(12:31):
approved and available in about ten totwenty countries worldwide, but they are generally
only available for at risk groups andfor anybody that has had laboratory confirmed previous
infection. The vaccine only provides protectionagainst severe Denghi for people who have already
(12:54):
had a confirmed case of Denghi.Anybody that was to be vaccinated that hasn't
had Denghi, then the vaccine mayserve as the first infection and therefore they
may be at increased risk of severeDenghy during subsequent infections. So prevention is
(13:16):
key, and preventions often through alayered approach. It's no use just putting
on insect repellent and hoping that you'llbe safe. There's a whole ecosystem of
interconnected actors that we need to consider, So the layer approach should really consider
personal prevention and protection, a teamapproach, a local environment or a camp
(13:41):
approach, and then a larger widercommunity approach. So individually, on a
personal level, we can avoid wearingshorts and t shirts avoid exposing our skin.
We can wear light colored, longsleeved clothing long trousers to prevent mosquitoes
(14:01):
landing on us and biting the skin. Utilization of repellent DET is without doubt
the best in the literature, butif anybody prefers a natural approach, then
there is good evidence to suggest thatthe natural lemon eucalyptus is the most effective
natural repellent. It's on power withDET, certainly for the first four to
(14:24):
six hours. Sleeping in mosquito netstreated with permthrine or some of the insect
repellent are very very useful to preventbites. But do consider local laws and
any local resistance to permthrine. Itmay be that permthrine is banned as it
is in Thailand, or there islocal or regional resistance, and other chemicals
(14:48):
might be recommended. Removal of standingwater sources is key. A couple of
centimeters of clean water is the perfectbreeding ground for the aides mosquito to lay
their eggs and continue the life cycleand contribute to the whole host of mosquitoes
within your operational area. So emptyout tires, empty out the water from
(15:11):
plant pots, try and remove thewater from any buckets baskets, set up
camps away from shallow ponds and pools, and then ultimately, if there's any
water sources that can't be eradicated,then you can consider treating the water with
larvicides or insect growth regulators. Acommon lava side is BTI or the BTI
(15:41):
bacteria, and I want to givethis pronunciation ago Bacillus thuringiensis israelensis or BTI
for short, ultimately to naturally occurringbacteria that comes in granules or tablets and
is added to the standing water tokill mosquito larvae. It's thought to be
(16:03):
harmless to humans and other aquatic wildlife. Simply add the correct dose of tablets
or granules. It dissolves in thewater and interferes with the growth of the
larvae and significantly reduces mosquito populations inthe area, but ultimately it should be
a two pronged attack. We're lookingat look reducing the larvae in the water
(16:29):
sources and then also the population ofadult mosquitos in the area. So space
spraying, fumigating, or fogging isuseful, and that can be done with
insecticide or adulticide to kill the adultmosquitoes in the area that often hang around
in dark shaded corners, lofts,foliage piles of duffel bags, And there's
(16:53):
two different systems really. There's thermalfoggers that use gas canisters to heat the
coils and generate the fog. They'rebest for outdoor use or very well ventilated
spaces, and then there's cold foggers, which are often battery operated or plug
into the mains and they're generally saferfor indoor use. On a more local
(17:15):
level, you've got spatial repellents suchas mosquito coils that you ignite or plug
in devices. Likewise, simple thingslike air conditioning or turning on fans will
circulate the air and potentially increase theairflow and push the mosquito away from you
so they can't land and bite youin the night if your budget allows as
(17:37):
a fantastic trap, a mosquito trapcalled the mosquito magnet. I've got no
commercial affiliation to these, but Ihave used them in tropical countries. And
this is a large device that runson propane gas and the machine essentially converts
the propane to CO two and heatand tracts and traps the mosquitoes within about
(18:03):
a two hundred foot radius, soextremely effective, but slightly more expensive than
your repellent or mosquito nets. Soit really comes down to the combination.
We need to be looking at personalprotection through insect repellents, appropriate clothing,
covering up skins, sleeping in mosquitonets. And then a team and a
(18:23):
camp approach, siting the camp awayfrom shallow water, removing standing water or
treating it daily, fogging either aroundthe camp or prior to your daily activities,
prior to patients turning up for medicalmissions, or prior to filming if
you're out on a shoot, andthen look at the broader community. If
(18:45):
there are cases of dinghy in thecommunity, and there are community members affected
or infected, and they come toworkers film extras or they come to your
clinics, then if there is amosquito population, they can bite the infected
community members, bite your team membersand continue this cycle of infection. So
(19:06):
we need to really think about howrisk mitigation should be broader and encompass the
local community. So let's get involvedwith the local leaders, look at the
local epidemiology, look at potentially educatethe local populace, or can we donate
insect repellent or mosquito nets to theat risk population. In practical terms,
(19:30):
out on the film set in atropical country during the rainy season, this
would really mean a full time jobfor the team. The team would arrive
on location about three am. They'dwalk around the set or the location emptying
pots, pans, and tires fromthe previous night's rain. They would accompany
(19:51):
the snake wrangler around to check thelocations for any unwanted guests, and then
ultimately fog the huts, bushers,drains, stores, baggage areas, kitchens,
leaving ample time for the fog orthe insector side to dissipate before the
crew arrived. Interestingly, though,rather than just eradicating mosquitoes everywhere we fogged,
(20:15):
it used to seem to drive thesnakes out into the open and we
found boa constricts and tree vipers allover the shooting location, which delayed shooting
on a couple of occasions. Soafter fogging, the team would wander around
checking the mosquito magnet traps, makingsure that it had power sufficient propane gas
(20:38):
were cited correctly based on the winddirection shooting location, so it's a fairly
dynamic job. They would have tomove the traps as the wind changed or
the shooting locations changed, and thenfollowing the daily preparation. Following the fogging
and the eradication of the standing water, the team would stay on set and
(21:00):
a company that the film crew allday offering insect repellent, clearing out any
other standing water as it rained,and then any other sources they would treat
with BTI in the background, Iwould meet with the Ministry of Health and
their delegates would collect mosquito or samplesfrom the site, taken them back to
(21:22):
the lab to determine the species,and then testing for pathogens such as denghy
zeka, chicken gunga, Japanese encephalitis, and I'm pleased to say they didn't
identify any on the location, butit was an ongoing process. So BTI
lots of questions surrounding that is itsafe for the environment, is it safe
(21:42):
for other aquatic life? And theCDC have produced a simple fact sheet on
BTI that you can access on theCDC website. But certainly if you're responsible
for fogging with insecticide, it's worthtaking a good look at them STS,
the Materials Safety data sheets, asthe insecticide can be harmful, can be
(22:04):
irritant on the skin, the eyes, the respiratory tract, so do work
with experts, have a look atthe msts and all ultimately make sure that
the fog has dissipated before the crewarrived to start work. Let's take a
look at the phases of DENGHI andsome of the signs and symptoms and the
(22:26):
diagnostic criteria. So the incubation periodsfive to seven days. Quite often patients
will develop a fever between thirty nineand forty degrees. The disease generally consists
of three phases febrile phase, thecritical stage, and the convalescent stage,
(22:51):
usually identified through two or more clinicalfindings. That the symptoms you might expect
to see could include that classic feverthirty nine to forty degrees celsius, headache,
retro orbital pain as a common complaint, muscle and joint aches, and
pains. Bone pain. Dengha usedto be called breakbone fever because of the
(23:15):
severe pain and the bones and themuscles, macular or macular popular rash and
potentially a positive tornica test. Sowhat is the tornica test? Ultimately it's
to identify pillary fragility. It's auseful clinical diagnostic method to determine a patient's
(23:36):
hemorrhagic tendency or status and potential forthrombocytopenia. And it's an accepted diagnostic tool
as cascaded by the World Health Organization. Very simple procedure. Place the blood
pressure cuff around the proximal arm,inflate the cuff to midway between the patient's
(23:57):
systolic and distolic pressure. Keep theblood pressure cuff inflated for five minutes.
At the end of the five minutes, the blood pressure cuff is removed,
and if there are more than twentypetikii in one square inch of skin,
(24:18):
that is classed as a positive testfor severe DENGHI. So there the standard
signs and we've got warning signs.Warning signs of the potential for development of
severe Denghi. So warning signs couldinclude abdominal pain, persistent vomiting, anorexia,
(24:41):
clinical fluid accumulation, and possible hypotension. Severe Denghi. We're looking at
a history of the clinical findings overthe previous two to seven days, evidence
of plasma leakage, evidence of shock, hematemesis, bloody stool bleeding, guns
(25:03):
epistaxis, respiratory distress, and alteredmental status. So how do we diagnose
it? Can we diagnose it?We're looking at the clinical findings contrasted with
the incubation period evidence of bites ina Denghy endemic area. Presenting with two
(25:29):
or more of the clinical signs,we would potentially assume it's Denghy. Likewise,
there is a PCR test for dengyor. There is an NS one
antigen test which is best done inthe first week since the onset of symptoms
and then in the second week sincethe onset of symptoms. There is an
(25:52):
IgM antibody test very similar to thecovid antigen and antibody tests. They're cheap,
disposable, and readily available in endemicregions Southeast Asia and Latin America.
So it is a non specific febrileillness, easily confused, potentially confused with
(26:18):
flu, malaria, zeka, chickengunga, COVID to name but a few.
So it's useful to keep an eyeout on the local trends. Is
there an increase in local outbreaks?Are there an increase in local cases?
Have we got appropriate mitigation measures inplace to prevent that cross infection through the
(26:38):
Denghy mosquito vector. And ultimately,if we can't diagnose it through the clinical
symptoms, the incubation period, etc. Then perhaps we can employ an NS
one antigen test or at the righttime, an antibody test, or if
you can get out from the remoteareas and get to lab that can do
(27:00):
dengy pc artists, then that mightbe useful to rule in or rule out
other pathology and specifically direct treatment.So what is the treatment for denghy?
Ultimately, there is no specific treatmentin denghy that presents with flu like symptoms.
(27:21):
The core treatment is hydration and paracetamol. Paracetamol is useful antipyretic. Likewise,
it can help with the muscle andbone aches and pains. But the
key here is to avoid drugs suchas aspirins or other non steroidal anti inflammatory
drugs due to their anticoagulant properties whichcould potentially exacerbate any bleeding. One consideration
(27:47):
when we're employing prolonged field care isto avoid exposure of the febrile patient to
mosquitoes to prevent onwards transmission to otherteam members. So if you do have
somebody in a remote area with afever and you suspect DENGHI, whilst we're
monitoring on monitoring them, checking onthem, arranging evacuation or laboratory tests,
(28:11):
that they should ideally be resting insidea mosquito net so any local mosquitoes can't
bite them and then go on tobite another team member and continue that chain
of infection. So general supportive treatmentfor DENGHI and then if there are any
signs of warning signs or severe DENGHI, then really it's employed the medical emergency
(28:33):
response plan best medicine being DIESEL andget off to the ICU so they can
be tested and provided with supportive treatmentand continual monitoring in hospital. So in
summary, I think any group travelingoverseas to not necessarily to remote areas because
DENGHI is prevalent in the urban andsuburban areas, not necessarily the deep tropical
(28:56):
rainforest. It's useful to do theresearch it's prior to heading out into these
areas, and as we always do, look at the current medical threats in
that specific area, Look at thecurrent endemic diseases, any areas of specific
outbreaks, the season, the timeof year, any specific threats that we
(29:17):
can identify through local reconnaissance, speakingto local leaders the Ministry of Health,
identifying potential filming locations, campsite locations. Are there any potential static water sources
or standing water sources that we caneradicate or if we can't, can we
identify local suppliers to provide larvicides BTI, local contractors to support with space spraying,
(29:44):
fogging or fumigation. Have we gotappropriate date inset repellent, appropriate clothing
with long sleeves, long trousers tocover up the skin, mosquito bednets to
protect ourselves. Community initiatives to lookat the wider community and perhaps how we
(30:04):
can support the community and break thelife cycle around the community and ultimately have
the community server as an extra layerof protection for our team and Likewise,
our team can serve as a layerof protection for the local community. So
that layered approach of prevention prevention preventionis really important and certainly requires a little
(30:27):
bit of forward planning rather than justturning up on the ground and trying to
cuff it through ad hoc measures.Hopefully that short introduction was useful to present
the expanding scale and scope of Denghi, the life cycle, some of the
preventative strategies and the layered approach alongwith some of the signs, symptoms and
(30:49):
diagnostic tools of Denghi, along withthe treatment and went to seek support.
Hopefully that will help you to planany future missions and mitigate any potential patients
in the future. If anyone's interestingfurther reading, there's the Denghi A Guide
to Prevention, Diagnosis and Field Treatment, which is available on Amazon and again,
(31:11):
all the proceeds from the sale ofthat book go back into our medical
missions and help us to provide mosquitonets, insect repellents and testing kits for
our communities down in southwest Guatemala.And the next medical mission will take place
in May twenty twenty four, followingthe Red Mead course. The Rex who
(31:33):
rescue Expedition disaster medicine course in Guatemalawhere we will be rafting through the jungle,
setting up jungle camps, jungle survivaltrekking a high altitude volcano and traveling
through the Land of Eternal Spring orMundo Maya. And those of you that
want to stay on for a coupleof days at the end can help out
(31:53):
with a medical mission. We're reachingout an appealing to for support from all
allied health professionals, anyone from EMTsthrough nurses, pas, paramedics, doctors,
dentists, surgeons that the communities needyour support. So if you want
to do the Red Mead course,please do get in touch. And if
(32:15):
you need to head straight home,that's cool. If you'd like to stay
in Guatemala, you can stay andjoin us for a couple of days at
the medical mission, wrapt through thejungle, get to the community and then
will be involved in everything from dentalcare, primary care, to helping the
community understand the different methods of watertreatment. And then we'll be employing different
(32:37):
workshops to help mitigate mosquito born diseases. But before that, in October November
this year, twenty twenty three,we've got the Red Mead course in the
poll, and we'll be employing theflipped classroom approach, so there's a period
of online self paced learning so thatwhen you arrive you can thoroughly enjoy the
(32:58):
Kumbo Valley and the incredible views ofthe eight thousanders as we trek towards Everest
Based Camp, doing having team discussionsaround the fire pits in the tea houses,
and then employing skills and scenario basedtraining in context in the shadow of
Everest at Everest Based Camp before goingon to do a mountaineering training day and
(33:21):
attempting a climb on a six thousandmeter peak, namely Low Boschet East at
six one hundred and nineteen meters.So all the way we'll be talking about
patient assessment, altitude sickness, hypothermia, frostbite, prolonged fieldcare, patient packaging,
helicopter safety, communications, telemedicine,medical emergency response planning, risk assessments,
(33:42):
fractures, analogies, all of thatkind of good stuff, supported by
the Red Mead faculty and our incredibleclimbing sherpas who between them have got numerous
ascent of Everest and K two.So if that sounds like fun. If
that sounds like you, do,get in touch. There are still spaces
on the October course, and ifnot, we've got the UK based course
(34:05):
coming up in February twenty twenty fourand we'll be looking at topics such as
disaster medicine, helicopter safety, mountainmedicine, search and rescue, heat,
cold bite, stings, and anawful lot of the non clinical competencies such
as mission planning, obstacle crossing,etc. Anyway, guys, thanks for
(34:25):
tuning in, thanks for listening,Thanks for your support. Wherever you are
in the world. Stay safe andhook your speak to you soon. Bye bye
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