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The commonest problem facing travellers is traveller's diarrhoea but other important diseases caused by poor sanitation include hepatitis A, and worm infestations such as hookworm and schistosomiasis.
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Contamination of food and water is a major problem, especially in third world countries.
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Reputable soft drinks, such as Coca-Cola, should be recommended for drinking. Indian-style tea, in which the milk is boiled with tea, is usually safe, but tea with added milk is not. The food handlers can be infected and the water used to wash food may be contaminated.
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Traveller's diarrhoea
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Traveller's diarrhoea is a special problem in Mexico, Nepal, India, Pakistan, South-East Asia, Latin America, the Middle East and Central Africa and its many colourful labels include ‘Bali Belly’, ‘Gippy Tummy’, ‘Rangoon Runs’, ‘Tokyo Trots’ and ‘Montezuma's Revenge’. It occurs about 6–12 hours after taking infected food or water.
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The illness is usually mild and lasts only 2 or 3 days. It is unusual for it to last longer than 5 days. Symptoms include abdominal cramps, frequent diarrhoea with loose, watery bowel motions and possible vomiting. Very severe diarrhoea, especially if associated with the passing of blood or mucus, may be a feature of Shigella sp or Campylobacter sp infections and amoebiasis.
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Most traveller's diarrhoea is caused by enterotoxigenic E. coli (ETEC), Campylobacter sp, Shigella sp and Salmonella sp. Travellers are infected because they are exposed to slightly different types or strains of E. coli from the ones they are used to at home.2
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The possible causes of diarrhoeal illness are listed in TABLE 14.1.
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The key factor in treatment is rehydration.
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Maintain fluid intake—Gastrolyte.
Antimotility agents (judicious use: if no blood in stools)—avoid in children.
loperamide (Imodium) 2 caps statim then 1 after each unformed stool (max. 8 caps/day)
or
diphenoxylate with atropine (Lomotil) 2 tablets statim then 1–2 (o) 8 hourly
Imodium is the preferred agent.
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Severe diarrhoea (patient toxic and febrile)
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?Admit to hospital.
Attend to hydration—use an oral hydrate solution (e.g. Gastrolyte).
Loperamide in adults.
Antibiotic: norfloxacin (first choice), ciprofloxacin or azithromycin (usually 3 days).
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Note: There is increasing resistance to doxycycline and cotrimoxazole, especially in South-East Asia.
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Any travellers with persistent diarrhoea after visiting less-developed countries, especially India and China, may have a protozoal infection such as amoebiasis or giardiasis. If the patient has a fever and mucus or blood in the stools, suspect amoebiasis. Giardiasis is characterised by abdominal cramps, flatulence, and bubbly, foul-smelling diarrhoea persisting beyond 2 to 4 days. Take three specimens of faeces for analysis. In some cases serology may be helpful (e.g. amoebiasis).
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Patients can self-administer these drugs and carry them if visiting areas at risk, but they can have a severe disulfram-like adverse reaction with alcohol.
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The following advice will help prevent diseases caused by contaminated food and water. These ‘rules’ need only be followed in areas of risk such as Africa, South America, India and other parts of Asia. Only drink purified water and only eat well-cooked food.
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Purify all water by boiling for 10 minutes. Adding purifying tablets is not so reliable, but if the water cannot be boiled some protection is provided by adding Puratabs (chlorine) or iodine (2% tincture of iodine), which is more effective than chlorine—use 4 drops of iodine to 1 litre of water and let it stand for 30 minutes.
Avoid ice in your drinks unless known to be safe. Drink only boiled water (supplied in some hotels) or well-known bottled beverages (mineral water, 7-Up, Coca-Cola, beer).
Brush your teeth using purified water.
Avoid fresh salads or raw vegetables (including watercress). Salads or uncooked vegetables are often washed in contaminated water. Bananas and fruit with skins are safe once you have peeled and thrown away the skin but care should be taken with fruit that may possibly be injected with water.
Be wary of dairy products such as milk, cream, ice-cream and cheese.
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Avoid eating raw shellfish and cold cooked meats.
Avoid food, including citrus fruits, from street vendors.
Drink hot liquids wherever possible.
Use disposable moist towels for hand washing.
Vaccines against ETEC are in development.
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Golden rule for preventing diarrhoea
If you can't peel it, boil it or cook it—don't eat it.
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Travellers to all tropical countries are at some risk of this protozoal infection.
Malaria is endemic in 102 countries;4 2.3 billion people are at risk, with 500 million affected every year.
The risk is very low in the major cities of Central and Southern America and South-East Asia but can be high in some African cities.
In humans malaria is caused by four species of plasmodium:
– Plasmodium vivax and P. ovale—tertian malaria
– P. falciparum—malignant tertian malaria
– P. malariae—quartian malaria
– P. knowlesi—presents like vivax and falciparum
Malaria is either benign (vivax, ovale) or malignant (falciparum).
Resistance to many drugs is increasing:
– The lethal P. falciparum is developing resistance to chloroquine and the antifolate antimalarials (Fansidar and Maloprim).4
– Resistance is now reported to mefloquine and artemether.
– Resistance is common in South-East Asia, Papua New Guinea (PNG), northern South America and parts of Africa.
Chloroquine is used infrequently as it is only effective in limited areas of the world but not PNG.
The long-awaited vaccine will make all the complex drug management much simpler. However, it still appears to be many years away despite considerable research.
Patients who have had splenectomies are at grave risk from P. falciparum malaria (PFM).
People die from malaria because of delayed diagnosis, delayed therapy, inappropriate therapy and parasite–host factors.
It is recommended that pregnant women and young children do not travel to malarious areas (if possible).
Practitioners should follow updated recommended guidelines (e.g. WHO therapeutic guidelines (antibiotic)).
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DxT fever + chills + headache ➜ malaria
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Malaria risk assessment
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The risk of catching malaria is increased by:
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being in a malaria area, especially during and after the wet season
a prolonged stay in a malaria area, especially rural areas, small towns and city fringes
sleeping in unscreened rooms without mosquito nets over the bed
wearing dark clothing with short-sleeved shirts and shorts
taking inappropriate drug prophylaxis
an incomplete course of prophylaxis
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Travellers should be advised that malaria may be prevented by following two simple rules:
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avoid mosquito bites
take antimalarial medicines regularly
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In order to avoid mosquito bites, travellers are advised to:
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keep away from rural areas and avoid outdoor activities between dusk and darkness
sleep in air-conditioned or properly screened rooms
use insecticide sprays to kill any mosquitoes in the room or use mosquito coils at night
smear an insect repellent on exposed parts of the body; an effective repellent is diethyl-m-toluamide (Muskol, Repellem, Rid)
use mosquito nets (tuck under mattress; check for tears)
impregnate nets with permethrin (Ambush) or deltamethrin
wear sufficient light-coloured clothing, long sleeves and long trousers to protect whole body and arms and legs when in the open after sunset
avoid using perfumes, cologne and after-shave lotion (also attract insects)
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Important considerations in malaria prophylaxis
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Minimise exposure to mosquitoes and avoid bites.
Know areas of risk:
tropical South America (southern Mexico to northern half South America)
tropical Africa (sub-Sahara to northern South Africa)
Nile region, including remote rural Egypt
Southern Asia, especially tropical areas
Know areas of widespread chloroquine resistance:
Consider several factors:
Know the antimalarial drugs (see TABLE 14.2).
Balance risk benefit of drug prophylaxis: drug side effects versus risk of PFM.
Visiting areas of PFM does not automatically require the use of potentially harmful drugs.1
Those at special risk are pregnant women, young children and the immunocompromised. Advise against travel.
No drugs give complete protection.
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Refer to WHO guidelines (www.who.int/ith/en).
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Accommodation in large, air-conditioned hotels in most cities of South-East Asia (dusk–dawn) for <2 weeks: no prophylaxis required.
For low-risk travel (urban: dusk–dawn) in areas of high resistance for <2 weeks: doxycycline is adequate; use a treatment course of Malarone if necessary (see TABLE 14.3).
Chloroquine is no longer recommended because of the global spread of resistance.
For short- and long-term travel to rural areas of high resistance (e.g. South-East Asia including Thailand, Kenya, Tanzania, Ecuador, Venezuela, Brazil): doxycycline daily alone or mefloquine (once a week). Atovaquone and proguanil (Malarone) is also very useful for short-term travel.
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Summary of malaria recommendations5,6
PFM area:
mefloquine 250 mg/week
or
doxycycline 100 mg/day
or
atovaquone + proguanil
Multidrug-resistant area:
Malarone for prophylaxis
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standby treatment: Malarone or artemether + lumefantrine (Riamet)