Central & South America health updates

26/04/2017 15:27

Written by Dr Felicity Nicholson

People new to exotic travel often worry about contracting tropical diseases but, with the right vaccinations and a sensible attitude to malaria, the chances of a serious incident are small. In fact the greatest risk to your health in South America is road accidents. Sadly these are all too common, so be aware and do what you can to reduce risks. Try to travel during daylight hours, always wear a seatbelt and refuse to be driven by anyone who has been drinking. Also, listen to local advice about areas where violent crime is rife.

Zika virus

Zika virus is a flavivirus similar to dengue and was first reported in 1947 in Uganda. It is spread by the day-biting Aedes mosquito. Since November 2014, it has been reported in South America where there is a strong association with congenital malformations in new born babies (microcephaly). All travellers to countries where zika virus occurs are at risk of infection. The longer you spend in the destination, the more at risk you will be.

The infection is often asymptomatic and in those with symptoms the disease is usually mild with an itchy rash, fever, joint pains and red sore eyes. Severe disease is uncommon.

Travellers are advised to use DEET-based repellents during the daytime on all exposed skin. In areas where mosquitoes are particularly prevalent, covering up and using a permethrin spray on clothing would also be advised.

Pregnant women need to discuss their travel plans with healthcare professionals and should, wherever possible, cancel the trip. Women wishing to become pregnant who are travelling in moderate- to high-risk zika virus areas should use barrier methods of contraception whilst travelling, and for two months after leaving the affected area. If travelling with their partners, then barrier precautions need to be used during the trip and for six months after leaving. For up-to-date details follow the link here.  

Travel insurance 

Don’t think about travelling without a comprehensive medical travel insurance policy: one that will fly you home in an emergency. It is worth testing the company that you pick by posing a scenario and seeing how they respond. Make sure that the policy covers any activities in which you might be wanting to participate.

Immunisations

Preparations to ensure a healthy trip to South America require checks on your immunisation status: it is wise to be up to date on tetanus, diphtheria and polio (now given as an all-in-one vaccine, Revaxis, that lasts for ten years), and hepatitis A. Immunisations against yellow fever, typhoid, hepatitis B and rabies may also be recommended. Other suggested vaccines could include BCG for tuberculosis, and MMR for measles, mumps and rubella.

Whether or not you need to have the yellow fever vaccine depends on the countries you are travelling to and from. There are two reasons for immunising against yellow fever, firs to protect against the disease and second as a certificate requirement to gain entry into a particular country. The World Health Organisation (WHO) recommends that this vaccine should be given to those aged nine months and over. It is now accepted that, for most people, the vaccine offers protection for many decades. As of 11 July 2016, all countries now have to accept that yellow fever vaccine lasts for life, regardless of when it was given. This means that as long as you have had the yellow fever vaccine and have a certificate, you won’t need to have the vaccine again unless you were immunocompromised at the time it was given or were under the age of two, when it will need to be repeated after ten years. If you have had the vaccine but have lost the certificate and are travelling to a country where there is a certificate requirement for entry, then you are likely to need the vaccination again. If you have never been vaccinated, you need to seek specialist advice from a registered yellow fever centre. Whether or not you need the vaccine has to be determined on an individual basis, based on the risk of the disease versus the risk to the traveller. There are certain medical conditions that mean the vaccine would be contra-indicated. If you are unable to have the vaccine then you may be advised to avoid the risk areas within certain countries, for example the Amazon basin. While the risk of yellow fever is not as high as in West Africa, the disease has a significant mortality rate in people who catch it who have never come into contact with the disease before and have never been vaccinated, ie are not immune.

Hepatitis A vaccine (e.g. Havrix Monodose, Vaqta or Avaxim) comprises two injections given at least six months apart. The course costs about £100, but may be available on the NHS, protects for 25 years and the first injection can be administered even close to the time of departure. The first dose of hepatitis A vaccine is thought to be protective for up to five years depending on where you intend to travel next. 

Hepatitis B vaccination should be considered for longer trips (two months or more) or for those working with children or in situations where contact with blood is likely. Three injections are needed for the best protection and can be given over a three-week period, if time is short, for those aged 16 or over. Longer schedules give more sustained protection and are therefore preferred if time allows. Hepatitis A vaccine can also be given in a combination with hepatitis B as ‘Twinrix’, though two doses are needed at least seven days apart to be effective for the hepatitis A component, and three doses are needed for the hepatitis B. Again, this rapid schedule is suitable only for those aged 16 or over.

Children aged 1–15 can be vaccinated with a junior version of this vaccine, but the minimum time frame for the three doses is a period of eight weeks. Children aged 1–15 can also be vaccinated with Ambirix, which consists of two doses given 6–12 months apart. One dose gives full protection against the hepatitis A and some protection against hepatitis B (though less than Twinrix). Having the second dose completes the course giving long-term protection against hepatitis A and hepatitis B. This vaccine is useful for children who are less tolerant of injections or have time for only one dose before travel.

The newer injectable typhoid vaccines (eg: Typhim Vi) last for three years and are about 75% effective. Oral capsules (Vivotif) are also available for those aged six and over. Three capsules taken over five days gives protection for approximately three years but may be less effective than the injectable forms as they rely on good patient compliance. Vivotif is also a live vaccine, which is not suitable for everyone. Typhoid vaccine should be encouraged unless the traveller is leaving within a few days for a trip of a week or less, in which case the vaccine would not be effective in time.

Vaccinations for rabies are ideally advised for everyone, but are especially important for travellers visiting more remote areas, especially if you are more than 24 hours from medical help and definitely if you will be working with animals (see Rabies).

Experts differ over whether a BCG vaccination against tuberculosis (TB) is useful in adults: discuss this with your travel clinic.

In addition to the various vaccinations recommended above, it is important that travellers should be properly protected against malaria in those countries where it is prevalent. For detailed advice, see below.

Ideally you should visit your own doctor or a specialist travel clinic to discuss your requirements, if possible at least eight weeks before you plan to travel. 

Travel clinics

A full list of current travel clinic websites worldwide is available on ISTM. For other journey preparation information, consult Travel Health Pro (UK) or CDC (US). Information about various medications may be found or Net Doctor. All advice found online should be used in conjunction with expert advice received prior to or during travel.

Avoiding insect bites

As the sun is going down, don long clothes and apply repellent on any exposed flesh. Pack a DEET-based insect repellent – ideally around 50% (roll-ons or sticks are the least messy preparations for travelling) – for use on all exposed skin and even some unexposed areas such as under socks. Insect repellent should be applied after sunscreen, ideally after a 20-minute interval. You also need either a permethrin-impregnated bed-net or a permethrin spray so that you can ‘treat’ bed nets in hotels. Permethrin treatment makes even very tatty nets protective and prevents mosquitoes from biting through the impregnated net when you roll against it; it also deters other biters. Otherwise retire to an air-conditioned room or burn mosquito candles/coils or sleep under a fan. Coils and fans reduce rather than eliminate bites. Travel clinics usually sell a good range of nets, treatment kits and repellents.

Mosquitoes and many other insects are attracted to light. If you are camping, never put a lamp near the opening of your tent, or you will have a swarm of biters waiting to join you when you retire. In hotel rooms, be aware that the longer your light is on, the greater the number of insects will be sharing your accommodation.

Aside from avoiding mosquito bites between dusk and dawn, which will protect you from elephantiasis and a range of nasty insect-borne viruses, as well as malaria, it is important to take precautions against other insect bites.

In lower-lying areas of South America you are at risk of day-biting mosquitoes (Aedes) that can carry dengue fever and zika virus, so it is important to apply DEET-based repellents on all exposed skin during daylight hours, as well as when the sun goes down. In more rural areas, such as the Pantanal in Brazil or the Amazon Basin, in any country it is wise to wear long, loose (preferably 100% cotton) clothes that have been impregnated with permethrin, which will kill the mosquitoes on contact. You can buy this clothing spray from most camping shops and pre-treat your clothes at home.  

Protection from the sun

Give some thought to packing suncream. The incidence of skin cancer is rocketing as Caucasians are travelling more and spending more time exposing themselves to the sun. Head for the shade between 11.00 and 15.00 and, if you must expose yourself to the sun, build up gradually from 20 minutes a day. To avoid burning, cover up in tightly woven clothing that is loose to allow air to circulate and wear a broad brimmed hat. Be especially careful of exposure in the middle of the day and of sun reflected off water and, when swimming, wear a T-shirt and lots of waterproof suncream (at least SPF 25 and a UVA of 4 stars or more). Sun exposure makes people prematurely wrinkly and increases the risk of skin cancer. The glare and the dust can be hard on the eyes, too, so bring UV-protecting sunglasses (British standard BS2724 1987) and, perhaps, a soothing eyebath. Remember children are particularly vulnerable and an SPF of factor 50 is recommended.

Personal first aid kit

 A minimal kit should contain:

  • A good drying antiseptic, eg: iodine or potassium permanganate (don’t take antiseptic cream)
  • Water purification tablets (chlorine dioxide) or a filter bottle eg: Aquapure
  • A few small dressings (Band-Aids)
  • Suncream
  • Insect repellent; anti-malarial tablets; impregnated bed-net or permethrin spray
  • A painkiller/anti-inflammatory (do not use aspirin or ibuprofen if you think you have dengue fever)
  • Antifungal cream (eg: Canesten)
  • Antibiotics for severe diarrhoea/bacillary dysentery 
  • Tinidazole for giardia or amoebic dysentery (see below for regime)
  • Antibiotic eye drops, for sore, ‘gritty’, stuck-together eyes (conjunctivitis)
  • A pair of fine pointed tweezers (to remove hairy caterpillar hairs, thorns, splinters, coral, etc)
  • Alcohol-based hand rub and soap (either a bar in a plastic box or as a liquid)
  • Condoms or femidoms
  • Needle and syringe kit accompanied by a letter from a healthcare professional
  • A digital thermometer (for those going to remote areas) and malaria treatment for longer or more remote travel.


Long-haul flights, clots and DVT

Any prolonged immobility including travel by land or air can result in deep vein thrombosis (DVT) with the risk of embolus to the lungs. Certain factors can increase the risk and these include:

  • Previous clot or close relative with a history 
  • People over 40 but > risk over 80 years
  • Having had an operation in the past two months
  • Cancer
  • Broken leg in a plaster
  • Some blood clotting disorders
  • Recent severe illness such as pneumonia, heart failure or a heart attack
  • Obesity
  • Pregnancy
  • Hormone therapy such as HRT or the combined oral contraceptive pill
  • People who are very tall (over 6ft/1.8m) or short (under 5ft/1.5m)

A deep vein thrombosis (DVT) causes painful swelling and redness of the calf or sometimes the thigh. It is only dangerous if a clot travels to the lungs (pulmonary embolus). Symptoms of a pulmonary embolus (PE) include chest pain, shortness of breath and sometimes coughing up small amounts of blood and commonly start three to ten days after a long flight. Anyone who thinks that they might have a DVT needs to see a doctor immediately.

Prevention of DVT

  • Keep mobile before and during the flight;
  • Bend and straighten your legs, feet and toes every half an hour when seated.
  • Drink plenty of fluids during the flight
  • Avoid taking sleeping pills and drinking excessive tea, coffee and alcohol
  • Consider wearing compression stockings (flight socks) ­– these must be measured and worn correctly. Ill-fitting stockings can actually increase the risk of DVT.

If you think you are at increased risk of a clot consult with a doctor. You may be prescribed blood-thinning drugs to lessen the risk or be advised not to travel.

Common medical problems

Water sterilisation

You can fall ill from drinking contaminated water, so try to drink from safe sources, eg: bottled water where available. If you are planning to visit more remote areas where safe bottled water is unlikely to be available, then consider buying a water filter system such as Aquapure. The filter in this system will remove all micro-organisms (bacteria, viruses, protozoa) and silt etc, and will filter around 350 litres of water before it stops working. No chemicals are involved so it works immediately and it is environmentally friendly as there is no need to dispose of the plastic bottles. Failing that, boil water thoroughly or sterilise with chlorine dioxide tablets. The latter are not the most pleasant tasting and take about 10 minutes to be effective. They do not work if the water contains any particulate matter.

Travellers’ diarrhoea

Travelling in South America carries a fairly high risk of getting a dose of travellers’ diarrhoea; perhaps half of all visitors will suffer and the newer you are to exotic travel, the more likely you will be to suffer. By taking precautions against travellers’ diarrhoea you will also avoid typhoid, paratyphoid, cholera, hepatitis, dysentery, worms, etc. Travellers’ diarrhoea and other faecal-oral diseases come from getting other people’s faeces in your mouth. This most often happens from cooks not washing their hands after a visit to the toilet, but even if the restaurant cook does not understand basic hygiene, you will be safe if your food has been properly cooked and arrives piping hot. The most important prevention strategy is to wash your hands before eating anything. You can pick up salmonella and shigella from toilet door handles and possibly bank notes. The maxim to remind you what you can safely eat is:

PEEL IT, BOIL IT, COOK IT OR FORGET IT.

This means that fruit you have washed and peeled yourself, and hot foods, should be safe but raw foods, cold cooked foods, salads, fruit salads which have been prepared by others, ice cream and ice are all risky, and foods kept lukewarm in hotel buffets are often dangerous. That said, plenty of travellers and expatriates enjoy fruit and vegetables, so do keep a sense of perspective: food served in a fairly decent hotel in a large town or a place regularly frequented by expatriates is likely to be safe. If you are struck, see below for treatment.

Treating travellers’ diarrhoea

It is the dehydration that makes you feel awful during a bout of diarrhoea and the most important part of treatment is drinking lots of clear fluids. Sachets of oral rehydration salts give the perfect biochemical mix to replace the fluids and electrolytes you are losing in the diarrhoea. If you don’t have any to hand then any dilute mixture of sugar and salt in water will be a suitable substitute: try Coke or orange squash with a three-finger pinch of salt added to each glass (if you are salt-depleted you won’t taste the salt). Otherwise make a solution of a four-finger scoop of sugar with a three-finger pinch of salt in a 500ml glass and add a squeeze of lemon or orange juice to improve the taste.  The juice also adds potassium, which is lost in diarrhoea. Drink two large glasses after every bowel action, and more if you are thirsty. These solutions are still absorbed well if you are vomiting, but you will need to take sips at a time. If you are not eating you need to drink 3 litres a day plus the same amount as whatever is pouring into the toilet. If you feel like eating, take a bland, high-carbohydrate diet. Heavy, greasy foods will probably give you cramps

Some people like to carry an antibiotic either because they will be remote from medical help or to treat travellers’ diarrhoea quickly. Drugs such as ciprofloxacin and rifaximin can be used to shorten travellers’ diarrhoea if they are started early enough in the illness. If the diarrhoea is bad, or you are passing blood or slime, or you have a fever, you will probably need a longer course of antibiotics in addition to fluid replacement. Some travellers also like to take antibiotics with them to treat bacillary dysentery – eg: azithromycin, ciprofloxacin or norfloxacin. Which drug to take, whether to treat simple travellers’ diarrhoea or bacillary dysentery, depends on the sensitivity of the organisms in the countries being visited and personal medical history, so seek expert advice before you travel. If the diarrhoea is greasy and bulky and is accompanied by sulphurous (eggy) burps, one likely cause is giardia. This requires a different treatment (tinidazole for preference but metronidazole will do). Again, some people like to take these medications with them.

Always seek medical advice as soon as possible if you have symptoms of giardia or you are vomiting or have other symptoms of bacillary dysentery or if simple diarrhoea fails to settle after a couple of days. Similarly, if the diarrhoea fails to settle after two doses of ciprofloxacin or the three-day course of rifaximin, then you should seek medical advice. Remember, children can succumb rapidly to dehydration and it is not advisable to give them antibiotics without first consulting a doctor.

Eye problems

Bacterial conjunctivitis (pink eye) can occur when travelling in South America; people who wear contact lenses are most open to this irritating problem. The eyes feel sore and gritty and eyelids will often be stuck together in the mornings. They will need treatment with antibiotic drops or ointment. Lesser eye irritation should settle with bathing in salt water and keeping the eyes shaded. If an insect flies into your eye, extract it with great care, ensuring you do not crush or damage it otherwise you may get a nastily inflamed eye from toxins secreted by the creature. The elongated and colourful blister beetles carry warning coloration to tell you not to crush them anywhere against your skin.

Prickly heat

A fine pimply rash on the trunk is likely to be heat rash; cool showers, dabbing dry, and talc will help. Treat the problem by slowing down to a relaxed schedule, wearing only loose, baggy, 100%-cotton clothes and sleeping naked under a fan; if it’s bad, you may need to check into an air-conditioned hotel room for a while.

Skin infections

Any mosquito bite or small nick in the skin gives an opportunity for bacteria to foil the body’s usually excellent defences; it will surprise many travellers how quickly skin infections start in warm humid climates and it is essential to clean and cover even the slightest wound. Creams are not as effective as a good drying antiseptic such as dilute iodine, potassium permanganate (a few crystals in half a cup of water), or crystal (or gentian) violet. One of these should be available in most towns. If the wound starts to throb, or becomes red and the redness starts to spread, or the wound oozes, and especially if you develop a fever, antibiotics will probably be needed: flucloxacillin (250mg four times a day) or cloxacillin (500mg four times a day). For those allergic to penicillin, erythromycin (500mg twice a day) for five days should help. See a doctor if the symptoms do not start to improve within 48 hours.

Fungal infections also get a hold easily in hot, moist climates, so wear 100%-cotton socks and underwear and shower frequently. An itchy rash in the groin or flaking between the toes is likely to be a fungal infection. This needs treatment with an antifungal cream such as Canesten (clotrimazole); if this is not available, try Whitfield’s ointment (compound benzoic acid ointment) or crystal violet (although this will turn you purple!).

Malaria

As of 16 October 2017, malaria risks in Central and South America have been downgraded by the Advisory Committee for Malaria Prevention (ACMP) following extensive monitoring. All of Central America has been downgraded to bite awareness, ie: the risk of disease has fallen below the threshold for taking tablets. Similarly most of South America has been downgraded and there are only a few areas where malaria tablets will be routinely advised including parts of French Guiana, Suriname and Guyana. However, certain medical conditions make some people more susceptible to malaria so tablets may still be advised even in the lower-risk areas, eg: those with sickle cell disease, immunocompromised patients, those with no spleens or very poor splenic function or who have multiple medical problems. Take country-specific advice from a travel clinic expert. Whether you are taking malaria tablets or not, it is important to take precautions to avoid being bitten in the first place (see Avoiding insect bites).

If you are advised to take tablets, then they are likely to be atovaquone/proguanil (eg: Malarone), doxycycline or perhaps mefloquine (Lariam)). The latter tend to be used for those who are either allergic to other tablets or have used them several times before without ill effect. Talk to your GP, a prescribing pharmacist or a travel health specialist to see which is best for you.

Pregnant women are discouraged from travelling to high-risk malaria areas in South America and would be wise to avoid the Amazon basin altogether as they are twice as likely to get malaria and have a poor outcome either for themselves or their foetus. Prescribing malaria tablets in pregnancy is not always straightforward. If you have to travel, then expert advice should be sought as to which malaria tablet would be suitable well in advance of travel. 

Other insect-borne diseases

Malaria is by no means the only insect-borne disease to which the traveller may succumb. Others include dengue fever, sleeping sickness and river blindness (see also Avoiding insect bites).

Dengue fever

Dengue fever is more common than malaria in many parts of South America and there are many other similar arboviruses, such as Chikungunya. These mosquito-borne diseases may mimic malaria but there is no prophylactic medication against them.

The dengue fever virus belongs to the family Flaviviridae, genus flavivirus (which includes yellow fever and Japanese encephalitis). The mosquitoes that carry the dengue fever virus typically bite during the daytime, so it is worth applying repellent if you see any mosquitoes around. Symptoms include strong headaches, rashes, excruciating joint and muscle pains and high fever.

Viral fevers usually last about a week or so and are not usually fatal. Complete rest and paracetamol are the usual treatment; plenty of fluids also help. Some patients are given an intravenous drip to keep them from dehydrating. Aspirin or ibuprofen should never be used as they can increase the risk of bleeding. It is especially important to protect yourself if you have had dengue fever before, since a second infection with a different strain can result in the potentially fatal dengue haemorrhagic fever.

Chagas disease

Also known as American trypanosomiasis, Chagas disease is a potentially life-threatening illness caused by the protozoan parasite Trypanosoma cruzi (T. cruzi). In Latin America the disease is mostly vector borne, where it is transmitted to humans by contact with the faeces or urine of the triatomine bugs, which are also known as kissing bugs in some countries. The bugs live in the cracked walls of poorly constructed houses in both rural and suburban areas. They are active at night when they feed on human blood. The bugs typically bite on the face and then defecate next to the wound. The parasite enters the body when the infected faeces are smeared into the open wound or into mucous membranes such as the eyes or mouth. Travellers can also contract this disease by eating infected food.

Chagas disease has two phases. The acute phase lasts for about two months after the initial infection. Most cases during this phase have few or no symptoms. Less than half have skin lesions, or present with fever, headache, enlarged lymph nodes, abdominal or chest pain. During the chronic phase, the parasites hide in the heart or digestive muscles. About a third of patients suffer from cardiac disorders and up to 10% have digestive problems. Death can occur from heart failure.

Benznidazole and nifurtimox can effectively treat Chagas disease if given early in the acute phase. They are less effective the longer a person has been infected.  It can be reduced or avoided by the following:

  • Avoid sleeping in a mud, thatch or adobe house. These types of residence are more likely to harbour triatomine bugs.
  • Use permethrin-impregnated bed-nets when sleeping in thatch, mud or adobe houses.
  • Use insecticides to remove insects from your residence.
  • Use DEET-based insect repellent on all exposed skin.                                                                                                                 

Onchocerciasis 

This disease, also known as river blindness, is hypoendemic in Brazil, Venezuela and Colombia. The risk of infection is greatest in the dry season.

It is caused by a nematode worm (Oncocerca volvulus) and is spread by the bite of a blackfly (Simulium species) which breeds in fast-flowing water. The blackfly bites mostly at dawn and dusk. The microfilaria released by the blackfly causes skin irritation with intense itching which usually occurs months or years later. The cornea can be affected, leading to blindness (hence the name), but this is rare in travellers.

Usually infection follows multiple bites, so those staying in the endemic countries listed such as aid workers, missionaries and military personnel are potentially at higher risk. Travellers who are living near rivers, particularly camping, are again at higher risk. The risk for most travellers is low. The recommended treatment is ivermectin, which needs to be given every six months for the life span of the adult worms or for as long as the infected person has evidence of skin or eye infection.

Prevention

Cover up and use DEET-containing insect repellents on all exposed skin. Sleep under permethrin-impregnated mosquito nets.

Leishmaniasis                                                                                                                       

In South America this disease is caused by a protozoan parasite (Leishmania braziliensis). It is spread by the bite of an infected sand fly (Phlebotomus species) which is mainly night biting and is most prevalent in forest or jungle areas.

There are two forms of the disease: cutaneous (affecting the skin) and visceral (affecting the organs). Brazil has the highest prevalence of both these forms in South America. The visceral form is usually fatal without treatment but thankfully the disease is rare in travellers. Those at highest risk are those trekking or living in the jungle. Treatment with liposomal amphotericin B is used for the visceral form and in most cases treatment is not needed for the cutaneous form but amphotericin B can be used.

Prevention

As sand flies bite close to the ground, the risk is reduced if beds are raised off the ground and you sleep under a permethrin impregnated bed net. Sand flies are small enough to be able to get through the mesh of the net.

Schistosomiasis (bilharzia)

Schistosomiasis affects only a handful of countries in South America, namely Brazil, Venezuela, Suriname, Guyana and French Guiana. It is caused by a microscopic flatworm (fluke) of the genus Schistosoma. The form that exists in South America is Schistosoma mansoni

It is an unpleasant problem that is worth avoiding, though can be treated if you do get it.

The risk is greatest for travellers who swim and bathe in fresh water (not sea or chlorinated water), particularly slow-moving or sluggish water, or who are exposed to water provided for washing from local lakes or rivers. By understanding a bit about the life cycle it is easier to prevent the disease, or recognise that you have it and therefore get treatment.

Eggs of the flatworm are excreted in faeces, which are then washed into the lake. The eggs hatch and the larvae that emerge infect certain species of snail. The snails then produce about 10,000 cercariae (larvae) a day for the rest of their lives. Winds will disperse the snails and cercariae. The snails in particular can drift a long way, especially on windblown weed, so nowhere is really safe. However, deep water and running water are safer, while shallow water presents the greatest risk. The larvae penetrate intact skin and find their way to the liver where they continue to multiply.

Although the adults do not cause any harm in themselves, after about four to six weeks they start to lay eggs, which cause an intense but usually ineffective immune reaction, including fever, cough, abdominal pain, and a fleeting, itching rash called ‘safari itch’. The absence of early symptoms does not necessarily mean there is no infection. Later symptoms can be more localised and more severe, but the general symptoms settle down fairly quickly and eventually you are just tired.

Schistosoma mansoni end up in the gut wall and can lead to abdominal pain, diarrhoea and symptoms of anaemia due to blood loss – either frank or occult. Often though there are no symptoms at all. With long-standing untreated infection, complications such as fibrosis/stenosis of the bowel can occur. Liver involvement can lead to hepatosplenomegaly, cirrhosis and portal hypertension.

Although bilharzia is difficult to diagnose, it can be tested at specialist travel clinics. Ideally tests need to be done at least six weeks after likely exposure and will determine whether you need treatment.  Fortunately it is easy to treat at present.

Avoiding bilharzia

If you are bathing, swimming, paddling or wading in fresh water that you think may carry a bilharzia risk, try to get out of the water within 10 minutes.

  • Avoid bathing or paddling on shores within 200m of villages or places where people use the water a great deal, especially reedy shores or where there is lots of water weed.
  • Dry off thoroughly with a towel; rub vigorously.
  • If your bathing water comes from a risky source, try to ensure that the water is taken from the lake in the early morning and stored snail-free, otherwise it should be filtered or Dettol or Cresol added.
  • Bathing early in the morning is safer than bathing in the last half of the day.
  • Cover yourself with DEET insect repellent before swimming: it may offer some protection.                               

HIV/AIDS

The prevalence of HIV is higher in nearly all South American countries than in the UK and the risk of sexually transmitted infections is greater whether you sleep with fellow travellers or locals. About 80% of HIV infections in British heterosexuals are acquired abroad. If you must indulge, use condoms or femidoms, which help reduce the risk of transmission. If you notice any genital ulcers or discharge, get treatment promptly, since these increase the risk of acquiring HIV.  If you do have unprotected sex, visit a clinic as soon as possible; this should be within 24 hours, or no later than 72 hours, for post-exposure prophylaxis.

Rabies

Rabies is carried by all warm-blooded mammals (beware the village dogs and small monkeys that are used to being fed in the parks) and is passed on to man through a bite, scratch or a lick (note that doctors now understand that even without an obvious wound, there is still a risk of infection from the saliva of an infected animal). You must always assume any animal is rabid as they can often look well but still be infectious. Seek medical help as soon as possible after any potential exposure. Meanwhile scrub the area that has been contaminated with animal saliva with soap under a running tap or while pouring water from a jug for a good 10–15 minutes. The source of the water is not important at this stage, but if you do have antiseptic to hand then put this on afterwards. The soap helps stop the rabies virus entering the body and along with an antiseptic will guard against wound infections, including tetanus.

Pre-exposure vaccination for rabies is advised for everyone but is particularly important if you intend to have contact with animals and/or are likely to be more than 24 hours away from medical help. Ideally three doses should be taken over a minimum of 21 days. All three doses are needed in order to change the treatment needed following an exposure.

If you are bitten, scratched or licked by any mammal, then post-exposure prophylaxis should be given as soon as possible – though it is never too late to seek help, as the incubation period for rabies can be very long. Those who have not been immunised before will need four to five doses of rabies vaccine given over 28–30 days and may also be advised to have a product called Rabies Immunoglobulin (RIG) either human or horse. The RIG is injected round the wound to try to neutralise any rabies virus present and is a pivotal part of the treatment if you have not had pre-exposure vaccine. RIG is expensive and may not be readily available as there is a global shortage, so it is important to insist on getting to a place that has it.  Another reason for having good insurance.

Tell the doctor if you have had two or more doses of the pre-exposure vaccine, as this will change the treatment you receive. If you have had all three doses then you will no longer need to have RIG and will probably only need a couple of doses of vaccine, ideally given three days apart. If you have had two doses of rabies vaccine pre-exposure, then in most cases you won’t need RIG but would still need to get five post-exposure doses of rabies vaccine over about 28 days. And remember that, if you do contract rabies, mortality is 100% and death from rabies is probably one of the worst ways to go.

Tick-borne diseases

Rocky mountain spotted fever

This is caused by the obligate intracellular gram-negative spirochete bacteria Rickettsia rickettsii. It is spread by the bite of ticks that live on rodents and dogs and is more risky for travellers if they are camping and hiking in rural areas.

The incubation is 2–14 days. The patient presents with an acute onset of fever, headache, abdominal pain, hypotension, rash, myalgia and arthralgia to name a few. There is a case fatality of 1.4%. It is treatable with tetracyclines, such as doxycycline 100mg twice daily for 7–14 days.

Prevention is always better than cure, so if you are going to be walking in rural areas, ensure that you are dressed appropriately with long sleeves, long trousers tucked into boots and a hat. At the end of the day check each other for ticks.

Ticks should ideally be removed as soon as possible as leaving them on the body increases the chance of infection. They should be removed with special tick tweezers, which can be bought in good travel shops. Failing that, you can use your fingernails: grasp the tick as close to your body as possible and pull steadily and firmly away at right angles to your skin. The tick will then come away complete, as long as you do not jerk or twist. If possible, douse the wound with alcohol (any spirit will do) or iodine. Irritants (eg: Olbas oil) or lit cigarettes are to be discouraged since they can cause the ticks to regurgitate and therefore increase the risk of disease. It is best to get a travelling companion to check you for ticks; if you are travelling with small children, remember to check their heads, and particularly behind the ears.

Spreading redness around the bite and/or fever and/or aching joints after a tick bite imply that you have an infection that requires antibiotic treatment, so seek advice.

Snakebite

Snakes rarely attack unless provoked, and bites in travellers are unusual. You are less likely to get bitten if you wear stout shoes and long trousers when in the bush. Most snakes are harmless and even venomous species will dispense venom in only about half of their bites. If bitten, then, you are unlikely to have received venom; keeping this fact in mind may help you to stay calm. Many so-called first-aid techniques do more harm than good: cutting into the wound is harmful; tourniquets are dangerous; suction and electrical inactivation devices do not work. The only treatment is anti-venom. In case of a bite that you fear may have been from a venomous snake:

  • Try to keep calm – it is likely that no venom has been dispensed.
  • Lie patient down away from the snake.
  • Do not apply a tourniquet.
  • Prevent movement of the bitten limb by applying a splint.
  • Keep the bitten limb BELOW heart height to slow the spread of any venom.
  • If you have a crêpe bandage, wrap it around the whole limb (eg: all the way from the toes to the thigh), as tight as you would for a sprained ankle or a muscle pull.
  • Evacuate to a hospital that has the relevant anti-venom.

And remember:

NEVER give aspirin; you may take paracetamol, which is safe.

NEVER cut or suck the wound.

DO NOT apply ice packs.

DO NOT apply potassium permanganate.

If the offending snake can be captured without risk of someone else being bitten, take this to show the doctor – but beware since even a decapitated head is able to bite.  

Updated 26 March 2018

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