You may be infected by a
neotropical disease in spite of every reasonable precaution. Share your recent
travel history with a physician who is competent in tropical medicine.
INGESTION: Water-born
diseases come from organisms such as viruses, bacteria, protozoa, fungus,
nematodes, flukes and tapeworms - to cite some general categories. Many
organisms can be avoided by drinking only water which has been 1) boiled, or 2)
filtered through a virus retaining filter or 3) chemically treated as with
chlorine or iodine compounds. Not all filters are equal. Some water treatment
systems filter out only bacteria and larger organisms, others filter out bacteria
and some smaller organisms. The Katadyn-Exstream is a personal filtration water
bottle that is known by the EPA to chemically inactivate viruses as well filter
out all the larger pathogens. I use one. A cartridge is good for 100
liters-enough drinking water for a two to three week trip.
The greatest threat from
water-born diseases occurs in populated areas where fecal matter sanitation is
poorly, if at all, controlled. In these areas, ingest (i.e., drink, brush
teeth, mouth wash) only bottled water or water treated to inactivate pathogens.
Tap water may be used to wash hands, but use plenty of soap.
Normally, an enteric
infection requires a significant number of bacteria to establish an infection.
Our immune defenses tend to wipe out most of them. Thus, a small inoculum may
usually be tolerated. The situation is different for the causative bacterium of
cholera (Vibrio cholerae). This organism forms films of hundreds of thousands
of bacteria on the chitin surfaces of copepods, daphnia, waterfleas and other
crustaceans. Their ingestion normally introduces inocula large enough to insure
an infection.
Food plays a critical role
in the transfer of pathogens present in the soil and on the hands of
processors. Washing and soaking foods with chlorinated or iodinated water will
destroy most organisms, but by no means all. Cooking foods well destroys most
pests that are present on foods and is effective in killing parasites and
bacteria that may reside in meat. Trichinosis is caused by a parasitic nematode
surviving in the inadequately cooked meat of omnivores and carnivores.
A newly recognized threat
is that of prion-caused "wasting diseases" among them Scrapie, Kuru
and BSE. Prions are a potential
threat and can occur in meat from any infected source. Data about their prevalence is limited
to a few generally available species. The degree to which they are associated
with “bush meat” remains to be determined. Since prions are especially abundant in brain and spinal
cord, especially that from older animals, these tissues should be avoided as
food. Whether prions that are below the level of currently used detection
systems are more or less likely to be infective cannot be known. Prions show extraordinary chemical and
physical resistance. They are protein and seem to exert their action by
mechanisms such as orienting the folding of proteins. Cooking will not insure protection from prion-based
diseases.
In the kitchen the best
protection against human pathogens is strict personal hygiene practiced by the
staff. Tropical temperatures offer serious challenges to food preservation.
Contaminated food will quickly become a health hazard. In a good camp there are
no "leftovers". Fruits, washed and peeled, are prepared immediately
before use. Travel juices are often prepared from concentrates made by boiling
down lime or other citrus juices. Cooking, salting, sugaring, smoking and
drying are all time-honored food preservation techniques that are invariably a
part of our trip kitchens.
Dealing with enteric
diseases. The primary symptom of infection by enterobacteria is diarrhea.
Toxins that these bacteria release block the capacity of cells lining the gut
to retain cellular fluid. The result-watery stools-is inconvenient, but is the
least problem associated with the infection. The loss of ions and changes in pH
is a major assault on the body's capacity to maintain a normal physiological
balance and, if untreated, could be lethal.
Rather simple steps can be
taken to address the intestinal problems: several formulations exist for
replacement salts that can be reconstituted and fed to the affected person,
loperamide tablets are readily available to reduce salt loss, and bismuth
tablets seem to reduce the symptoms.
At a minimum your medical kit should include these medicines.
EXTERNAL THREATS: The
variation of assaults from accidental stings, bites and punctures in the
tropics is truly phenomenal. Really alert woodsmenship can prevent most of
these. Virtually any leaf, branch or stump can harbor wasps, ants, bees,
spiders, scorpions and caterpillars, any of which can give you a painful
moment. For a person with a typical immune reaction most single events are not
usually dangerous to your health, but the effects of a single sting or bite can
be sufficiently long-lasting to spoil your trip. On the other hand, encounters
with colonial species such as ants, wasps or bees can be deadly. If you do
disturb these insects, mobility is your best defense. Remove yourself from the
area pronto.
Whether you or your
companions have a known allergic reaction to bee stings, wasps or scorpions or
have a history of hypersensitivity, be prepared. Carry medication
(antihistamines) to prevent anaphylactic shock. If you are hypersensitive,
always be sure the rest of the party knows about your condition or changes in
your well-being.
Keep your skin intact!
Clean and bandage open wounds and use an antibiotic salve on them. Deep
punctures, including bee and wasp stings, must be cleaned, drained and
antibiotic treated. Any sign of swelling and especially reddening along venous
routes is serious. It implies a migrating intravenous infection and requires
immediate medical attention. It is advisable for the party to have access to
broad spectrum antibiotics.
PREVENTION IS YOUR BEST
PROTECTION, THE FOLLOWING RULES MAY MAKE A DIFFERENCE
Keep your hands to
yourself. Do not touch other life forms (trees, logs, bushes, fruits, moths,
caterpillars, animals etc.), unless you know what you are doing. Ask your guide
first. It goes without saying, don't eat what you're not familiar with. If you
are tempted to peer into hollow trees, as one of our members invariably does,
warily inspect them first for snakes, spiders, scorpions etc. before you commit
yourself. For examining dark holes a flashlight is in order. Trees such as
palms and bamboo and vines have punishing thorns, and often harbor protective
ants. Always move slowly and watchfully. Wear long-sleeved shirts and long
pants. This will help you avoid being bitten while your attention is fully on
the bird or subject at hand. In the event you accidentally disturb aggressive
creatures being fully clothed will afford some protection as you beat a hasty
retreat. Tropical sunlight can be intense. Together with a wide-brimmed hat,
this clothing is good protection against it. Clothes constructed of
UV-impenetrable fabric and especially designed for cool wearing are worth
checking out.
Shoes and Socks, Nothing is
more important for a biped than the condition of its feet. Sneakers or good
light hiking boots are essential. Fine weave cotton socks of a length well
above your ankles (athletic socks) are an important barrier to all sorts of
assaults. I usually take five pairs on a 2-3 week trip: one pair gets too
filthy to wear and needs washing, one gets lost in the laundry (just like at
home), one is in the process of drying, one pair is kept in the hammock for
night wear, the other for general use.
Long pants tucked into
socks provide an almost impenetrable barrier to ticks, flies, ankle-enamoured
mosquitoes and briars. Permanone and other insect repelling substances on
shirts, pants and socks add an important layer of protection. Pretreatment of
clothes with these synthetic pyrethrins inhibits mosquito and tick attachment
and is thus an important part of prevention of insect-born disease. Since
permanone spray is effective on clothing for 5-6 washings, it is ideal for
extended jungle travel. Reports suggest that it is not taken up by the skin.
Use of “deet” is a third
barrier to attack by mosquitoes, flies and ticks. Fifty years studying
biochemistry has not endeared me to the idea of bathing in weird mixtures of
organic chemicals! However, a real threat must be addressed, while a
hypothetical threat can (for the moment) be ignored. So, when flying insects
are evident, it is a reasonable action to use deet, carefully. I have been on
trips to Guyana when you couldn't buy a mosquito! But that is not a guarantee,
so bring a supply of deet. Use it carefully on your clothes and if the occasion
warrants on your skin.
Another of the well-respected
pests of Guyana is the kaboura fly. It is a numerous, tiny, daytime biting
member of the blackfly (Simuliidae) family occurring near running water (the
larval form is a filter feeder). Like the blackfly, deet is effective against
it. The kaboura can be a real annoyance but to my knowledge the kaboura is not
a vector for a significant disease.
Mosquito netting is one of
the best protective devices. While sleeping we are especially susceptible to insect
attack because we're tied to one spot and (somewhat) unaware of insect attacks.
A hammock enclosed in a good mosquito netting is a safe haven. However, even
here mosquitoes can reach you since in twisting and turning, there is
opportunity for your appendages to come in contact with the mosquito netting
itself. Experienced campers spray permanone on the netting where limbs can come
into contact with it. Bring a spare can of permanone. For obvious reasons, keep
your sleeping net zipped up both when you are in it and when you are not.
Another precaution that I practice is to sleep in my clothes and with socks on
to reduce insect exposure.
From what are we
protecting?
Malaria (Plasmodium sp.)
carrying mosquitoes are a dangerous pest. The primary vectors are night-flying
(Anopheles) mosquitoes. Partial prophylaxis (about 65%) can be achieved by a
regime of mefloquinone (Lariam, for instance). Lariam is taken one pill per
week before, during and for several weeks after a tropical tour. (Note: Roche
is currently investigating Lariam, long known to be associated with
psychological side affects and seizures for the possibility that it may be
linked to suicide). Glaxo-Welcome also offers a new drug, Malarone, taken daily
that apparently works by interrupting the plasmodium reproductive process.
Malaria can be avoided by sleeping under mosquito netting and otherwise
reducing exposure to insects during the night. Take exceptional precautions in
villages. Inhabitants are potential malaria carriers. Malaria has been reported
in subjects months after a likely exposure! Thus, report any subsequent chills
and fever to your physician at once. Since malaria is presently not the usual
diagnosis in the US or northern Europe, suggest that it is a possibility.
Yellow Fever is caused by a
mosquito-born (Aedes and other forest species) virus that can kill up to 10% of
infected people. Immunity for 10 years can be gained with a single shot. Get
shot! Another viral pest carried by Aedes mosquitoes is Dengue Fever for which
no immune regime has been recommended. Stay covered up.
Hepatitis A is a viral
disease transmitted through exposure to feces from infected individuals; ie.,
contaminated water, food, or hands. A two-shot effective vaccination program
exists. Get vaccinated!
Leishmaniasis is a
protozoan infection that causes unmistakable sunken skin ulcers and much more
dangerous systemic problems. The vector is a biting sandfly. The above
repellents and covering up precautions should suffice. Note: is not a commonly
occurring disease in the U.S. and may express itself weeks or months after your
travel. Tell your doctor where you've been.
Chiggoes (not chiggers!)
are sand-fleas which deposit a subcutaneous egg-case at the interface of
cornified and smooth tissue, often on the soles of the foot or near the
toenails. The developing larvae swell and can be quite incapacitating. Their
existence is one of the reasons I wear socks in my hammock.
Botfly larvae. This is an
infection in which the larvae of the botfly embeds itself under the skin and
proceeds through its normal course of development. Of course, as the larvae
grows, it wiggles and turns and makes itself known. Suspect any swelling skin
bump-anywhere. The story is even more curious since the botfly is said to catch
a mosquito, attach its egg to the leg of the mosquito and then the mosquito
finds the host onto which the egg hatches and the larvae burrows. Too many
botfly infections can absolutely ruin a good cowhide. Think what it can do to
your hide! It's a rare physician in the northern U.S. who can instantly figure
out what's crawling under your skin. Suggest this possibility.
Ticks and chiggers are
commonly associated with brush and grassy areas. They are noticeably absent
from regularly flooded areas (varzea). Thank God for little fishes! Tuck your
pants into your socks. Be careful where you sit. A colleague in Tennessee once
demonstrated chiggers to me by placing his pocket-warmed wallet on some dry
grass where it quickly turned red as chiggers swarmed over it. The combination
of permanone-treated clothing and deet works. Special attention is essential
with deet and repellent on socks and pant legs where chiggers/ticks abound.
I've found that some of the neotropical ticks waste no time in embedding.
Unlike our northern dog/deer ticks that often wander about for hours, these
guys can attach within a minute. Check bare skin regularly. Chiggers seem to
attach in the area where clothing is tight such as the belt-line or at the
elastic of socks. While arachnids may be architecturally and chromatically
attractive, as a general rule, stay clear of them.
BIGGER STUFF. Wading in
rivers is an opportunity to encounter larger critters. Stingrays abound in the
larger streams. They are not venomous but the spines on their tails can inflict
serious puncture wounds that often lead to sepsis. If you must wade, sweep the
bottom ahead of you with a stick, or going upstream splash water ahead to flush
out any rays in your path (they otherwise don't know you're coming because
they're facing upstream and oblivious).
Electric eels can pack a
considerable punch, 6-7 pulses of 500 volts in milliseconds. They are a common
large fish in the rivers. Happily, they're not interested in finding you, so
wade noisily to let them know where you are.
Candiru is a pencil-thin
catfish whose niche is small cavities in other animals i.e., gill slits in
fish. Being an unschooled fish and unfamiliar with biological architecture, it
is reported to lodge in non-fish orifices such as urethras, vaginas and anal
cavities where their spines, projecting at right angles, make them difficult to
remove. Our guides tell us they able to target such sites by the odor of
excretion products and recommend not urinating while immersed in streams.
The Black Caiman, a
crocodilian relative is the largest reptile in the area. It does not have a
uniformly bad reputation. Nevertheless, its size, up to 20 feet long, and a
carnivorous appetite suggests it should be avoided. Likewise avoid the Anaconda
whose length approaches 20 ft. On the Cuyuwini River an area called Blackman's
Rock is said to commemorate the death of a traveler by an anaconda. As a general rule be extra
alert whenever you are at the water's edge where these reptiles hunt and rest.
Poisonous snakes are not
often encountered. There are three general types of poisonous snakes: pit
viper/rattlesnakes types, coral snakes and rear-fanged snakes. Bushmasters are
large vipers with the reputation of having an aggressive temperament.
Rattlesnakes are reported from time to time. Snakes are generally alert to
intruders in their space and will usually avoid a confrontation. You are
advised to move slowly but let them know of your approach by a modest amount of
noise and vibration. The only rear-fanged snake I've seen was stepped over by
line of six hikers all of whom assumed it was a vine lying across the
trail. Rear-fanged and coral
snakes, while not generally aggressive, are cryptic and likely to be hidden.
The danger is that you may encounter them when you least expect. As always- keep
your hands to yourself.
Don't touch snakes, frogs,
toads, scorpions, centipedes or unknown little things that the camp lights lure
in at night. Carry a flashlight for nocturnal wanderings and avoid touching
anything that you haven't shined your light on. This includes posts, tables,
chairs and john supports. Snakes rule at night in the forest on its floor,
bushes and trees. So be alert, use your flashlight, move carefully and slowly
(if that is an option). The simple precaution of removing shoes and clothing
only within the protection of your mosquito-tented hammock will keep your
sleeping quarters free of unwanted guests.
The Jaguar at a maximum
weight of ~300 lbs is the largest jungle cat. The Puma up to approximately 230
lb may occur anywhere. You may certainly hear one or the other, but you will be
unlikely to see either. These very large cats are to be avoided. If you see
one, it is because it wants you to see it. Most probably, what you are seeing
is a threat display because it protecting something: a food source or an
offspring. Clearly, it does not want you there.
Try to figure out where it
doesn't want you to go, and remove yourself carefully from that area. Don't run
(you're not prey, so don't act like it), don't crouch, (you're not about to attack),
instead make yourself as big as you can. Don't take your eyes off the animal.
Let it know what you are doing. Back away slowly.
White-lipped Peccary (max ~90 lbs.) is another potentially dangerous mammal. They are not intentionally aggressive, but they forage in herds, are very quick and protective of their young and in their rapid movements could accidentally surround and mob you. Avoid them. Hint: they don't climb trees.