Risks of Infection

These are some of the disease hazards you may encounter during your travels. There are many more …

INDEMNITY: This information is offered without charge to potential travellers. It is NOT intended as a complete list of all the risks encountered at these (or other) destinations. Consultation with a qualified doctor at a travel clinic is recommended. Travelsafe Clinic is not responsible for any infection/illness resulting from the use of the information at this site or in any of our published brochures.


Visitors to high-altitude destinations (particularly for mountaineering and skiing) are advised to take some precautions. In Colorado, USA there are an estimated 20 million visitors each year who venture above 2440 meters altitude or higher.
High altitude is a low oxygen environment. (In Denver, for example, air pressure is 17% less than at sea level – and thus contains 17% less oxygen. The air at Aspen, Colorado – 2438m – has 26% less oxygen).

People at high altitude become dizzy, faint and rapidly lose consciousness. Acute mountain sickness is the most common of the high altitude illnesses.
Medical treatment can be offered to travellers before such trips – to minimise the symptoms of this illness and to acclimatise quicker.


A blood fluke infection with adult male and female worms living in certain veins of the patient over a life-span of many years. These are several forms of blood flukes – and mixed infections are common.

The distribution in South Africa includes KwaZulu-Natal and virtually the entire country north of Johannesburg – extending into Botswana , Zimbabwe and Mozambique . Small areas of infection also occur near port Elizabeth and East London . In some endemic areas like Mpumalanga nearly 100% of rural school children are infected.

This infection is acquired from contact with water containing free-swimming larval forms which have developed in snails. The bilharzias life-cycle involves the release of the ora in human urine (haematobium) directly into natural surface waters – or in faeces (mansoni) which is then washed by rain into nearby surface waters. In the water, the ora hatch and eventually enter a suitable snail where development takes place.

Eventually fork-tailed larvae emerge and actively penetrate through healthy intact skin of people swimming or wading in the water. An immediate consequence of infection might be 'swimmer's itch' which usually occurs on the day of exposure and then subsides within a few days. People who have never had the infection previously might develop katayama fever between 2 weeks and 2 months of infection. This presents with a fever, diarrhoea, cough and swollen lymph nodes.

A third stage of blood in the urine and severe fever follows. Severe liver complications and bladder cancer may result with chronic infections.
The only prevention for travellers is to avoid bathing or swimming in contaminated lakes and rivers.


This is caused by a bacteria and will usually cause profuse watery stools and vomiting. Rapid dehydration may follow which may lead to the patient's death within a few hours. The mode of transmission is primarily through ingestion of water contaminated with faeces or vomits of patients or, to a lesser extent, faeces of carriers. It is often associated with flooding, poor water supplies and/or poor sanitation.

Cholera can be prevented by an oral vaccine dissolved in water. It's effectiveness is from six months to two years.


A severe mosquito-borne disease which occurs in most of tropical Asia – characterised by abnormal blood clotting. A sudden onset of high fever is accompanied by vomiting, headache and abdominal pain.

Outbreaks have occurred in the Philippines , Burma , Thailand , Indonesia , Malaysia , Singapore , Vietnam , Sri Lanka , India , Cuba and northern Australia .

No vaccine exists at present so insect-repellents are strongly advised.


A mosquito-borne disease where repeated infections cause severe deformities – occurring in tropical areas. There is no vaccination.


Food-borne intoxication or food poisoning are generic terms applied to illnesses acquired from the consumption of contaminated food and/or water.

Staphylococcal Food Poisoning
This is one of the principal acute food poisonings in the USA. It is an intoxication of abrupt and sometimes violent onset – with severe nausea, cramps and vomiting. This occurs 2-4 hours after an infected meal. Foods involved are particularly those which are handled by food vendors without subsequent cooking or with inadequate heating or refrigeration (custards, salad dressings, sliced meats etc.)

Vibrio Parahaemolyticus Food Poisoning
Watery diarrhoea and abdominal cramps follow after ingestion of raw or inadequately cooked seafood (or any food cross-contaminated by handling raw seafood in the same environment – or by rinsing with contaminated sea water).

Bacillus Cereus Food Poisoning
A well-recognised cause of food-borne diseases in Europe (rarely in the USA). Outbreaks characterised by vomiting have been most commonly associated with rice. Vegetables and meat dishes mishandled after cooking are often suspect.

There are an estimated 2 – 3 million salmonella infections in the USA annually. This is a bacterial disease commonly manifested by an acute enterocolitis with sudden onset of headache, abdominal pain, diarrhoea, nausea and sometimes vomiting. Fever is nearly always present. (Deaths are uncommon except in the very young, the very old or the debilitated).
The mode of transmission is ingestion of organisms in food derived from infected animals – or contaminated by faeces of an infected animal or person. This includes raw eggs, milk and/or meat products – especially poultry.


This infection has been known to occur throughout the world – from the sophisticated Western world to the hyper endemic areas of Africa, Asia and South America.

It is a viral infection of the liver and it is generally transmitted through food and water. Outbreaks have been linked to water, ice and shellfish – and to the consumption of salads, fruits and other foods pre-washed with contaminated water.
Patients usually become jaundiced with nausea, vomiting and joint pains that may last many weeks – while the patient is bed resting (often up to 12 weeks). It can be effectively prevented by a series of two injections, six months apart, to give immunity for the rest of your life. (Another option is a combination vaccination with Hepatitis B – a series of three injections)


This is a viral infection of the liver – which is contracted in the same way as the AIDS virus. In much of Africa, South America, China and south-east Asia the level of chronically infected people comprises between 5% and 15% of the population.

This disease may eventually lead to liver cancer.
Sexual transmission is highly efficient – as is percutaneous transmission from needle sharing, blood transfusions and traditional medical procedures (acupuncture and tattooing). Three doses of vaccine constitute the complete series of immunisation. The first two doses are usually given one month apart with the third dose about six months later. A further booster every five years is recommended. Vaccination is advised for travellers likely to engage in sexual or needle-sharing activities or those that may have to undergo dental or medical procedures while away.


A mosquito-borne disease (usually occurs in rural areas where pigs are reared). Vaccine is no longer available in South Africa – but can be obtained in Asian countries where the disease occurs.


It is estimated that up to 2,7 million people die from malaria every year. Malaria occurs in almost all of sub-Saharan Africa. In South Africa only in the low altitude areas (below 1 000 metres) in the northern part of the country. Malaria occurs in most South American and Central American countries (except for Chile, Argentina and Uruguay) and is particularly virulent in the Amazon basin. In South East Asia Malaria is widespread (from Eastern Turkey as far as Vietnam, Borneo and Papua New Guinea)

The female anopheles mosquito that carries the malaria parasite transmits the disease through her bite. The mosquito generally feeds between dusk and dawn, both indoors and outdoors.

Bites may be minimised by the following:
  • Apply a mosquito repellent to the exposed parts of your body (Wet wipes containing DEET).
  • Use mosquito nets in high risk areas
  • Cover exposed skin—particularly at sunrise and sunset.
Flu-like symptoms after returning from a malarial area must get immediate attention. Any person returning from a malarial area with these symptoms should immediately consult a doctor and mention that they have been exposed to malaria. Other symptoms include body pain, diarrhoea and vomiting. The usual incubation period for malaria is 14 days but it can take as little as a week to manifest itself – and as long as two months in some cases. Malaria prophylaxis is only obtainable with a doctor's prescription.
Note that no precautionary measures are 100% effective.
  • Some 90 countries/territories are considered malaria areas; almost half of them in Sub-Saharan Africa
  • Over 2000 million people are resident in such areas
  • Estimates of malarial mortality vary from 1,5 - 2,7 million deaths each year
  • Risks associated with malaria infection in pregnant women include spontaneous abortion in up to 60% of cases and a maternal mortality rate of up to 10%
  • In many areas the incidence of malaria changes from season to season - with rapidly emerging resistance to conventional therapies
  • All anti-malarial drugs are only available upon prescription
Older, over-the-counter anti-malarial drugs are, with very few exceptions, no longer recommended. All travel in Africa requires medication that may not be sold without a prescription.

Travelsafe Clinic was one of the testing centres for a new anti-malarial drug, 'Malanil' (called 'Malarone' elsewhere) that is now widely used in the western world. This drug, with all others, is available from our clinics.

Not all anti-malarial drugs need to be taken for extended periods before or after visiting a risk area. Some can be taken only one day before entering a risk area – and only for seven days after leaving. Consultation is, however, essential.

We do not recommend visits to any risk area without prophylaxis. We cannot support the idea that some drugs may 'mask' symptoms and thus make it preferable to take nothing – and then treat the illness should symptoms develop. Malaria is a serious illness and travellers should not take any unnecessary risks.

Young people can take most anti-malarial drugs – however, should small children (under 5 years old) become infected the consequences could be life threatening. We thus do not recommend that small children be placed at risk unnecessarily. Only essential travel into risk areas should be undertaken by such young travellers – and then with added precautions like mosquito nets, anti-mosquito lotions/wipes and repellents.

Malaria occurs in almost all of sub-Saharan Africa - in South Africa only in the low altitude areas (below 1 000 metres) in the northern part of the country.

DIVING NOTES Scuba divers are alerted to the fact that some malarial medicines may influence under-water judgement and orientation. It is thus important that a knowledgeable authority is consulted when planning a diving holiday at a malaria destination.


Meningococcal meningitis is an acute bacterial disease characterised by sudden onset with fever, intense headache, nausea and vomiting, stiff neck and frequently a rash.

Delirium and coma often result – and death may occur within a few hours if appropriate antibiotic treatment is not administered. This disease is spread through droplet infection from person to person – more often from 'carriers' than patients. One sneeze on an aeroplane can infect dozens of passengers or commuters in a crowded airport.

The risk to travellers planning to have prolonged contact with local populations in countries experiencing epidemics will be greatly reduced by immunisation. A single vaccine will give partial protection for three years.


Rabies is widely distributed in the world – and South Africa is no exception. Dogs are the most common source of human infection. About 20 cases are reported annually in South Africa – mainly in KwaZulu-Natal. There is also growing concern of this disease in the Eastern Province.

This is invariably a fatal disease contracted by virus-laden saliva after a bite from a rabid animal. The disease progresses to paresis or paralysis. Spasms of muscles on attempts to swallow will lead to a fear of water (hydrophobia). Delirium and convulsions follow. After 2 – 10 days death results (often due to respiratory paralysis).

The only areas free of rabies in the animal population (at present) include Australia, New Zealand, Japan, Hawaii, Taiwan, UK, Ireland, Spain, Portugal, mainland Norway, Sweden and some islands in the Atlantic Ocean and West Indies.


Since the disease in invariably fatal once symptoms supervene, post-exposure treatment is based on the principle of inducing immunity before the virus gains access to the nervous system. Victims must get treatment without delay.
Pre-exposure immunisation (3 injections within 1 month) may be offered to people who are either working in a rabies-infected area or spending more than a short holiday in an infected area (especially when back-packing or bush camping).
In areas of endemic rabies, domestic dogs and the cats should not be petted and contact with wild animals (especially bats, jackals, foxes, skunks, mongooses, raccoons and monkeys) must be avoided.


Tick-bite fever is transmitted by a hard tick. It is characterised by a primary sore (often having a blackish centre), swollen lymph nodes and, in most cases, by intermittent fever lasting 10 – 14 days.

Incubation period for this disease is about 7 days. There is a sudden onset with significant malaise, deep muscle pain, severe headache and conjunctivitis. A rash, appearing on the extremities about the 3 rd day, soon includes the palms and soles and spreads rapidly to most of the body. Bleeding underneath the skin is common. Blood tests may frequently be negative in the early stages – the diagnosis may therefore be missed if tests are not repeated!! The rash on the palms and sole is also a hot clue! No vaccine is presently licensed for public use. This disease requires specific antibiotic for treatment.

Tick-bite fever is widespread in south Africa – but especially common in the bushveld areas of Mpumalanga and the coastal belt from Port Elizabeth to the Mozambique border.

It has been shown that at all stages of development, the common dog tick (larva, nymph and adult) is infective and there is hereditary transmission of the disease through the egg to succeeding generations. (This is believed to continue indefinitely). Travellers should thus wear long trousers in the bush.


Food in foreign countries is often different from that to which the traveller is accustomed. Food often looks very appealing and the newly discovered tastes contribute to the enrichment of foreign travel. However, food may carry an important menace for the traveller's health. The reasoning "What is good for the local people cannot be bad", is only partially correct. The traveller must be aware that the local population may have developed resistance or tolerance to a number of harmful components of their food, such as parasites or other infectious agents.

The most important hazards related to food are infections. They relate mainly to the contamination of food by parasites, but also bacteria or viruses of human origin, present in human excreta. These can contaminate food by dirty hands or through water used in food preparation and which has been soiled by sewage or leakage from latrines used by humans. Human excreta used as fertiliser can carry dangerous parasites or germs. Improper hygiene of food and water leads to traveller's diarrhoea. Many of these infectious agents can be destroyed by heating, but a number stick to the surface of foodstuffs such as fruit and vegetables which we do not want to cook. The saying " Cook it, peel it or leave it ! " carries considerable wisdom. Meat and fish may contain parasites which undergo a biologic cycle ending in the animal. However, the intensive heat of frying, baking or stewing largely destroys these parasites

Bacteria are responsible for 50%-80% of cases of traveller's diarrhoea. (E.coli will be the most likely cause). Viruses are an uncommon cause of diarrhoea.

WATCH WHAT YOU EAT! Street vendors and open-air markets are more likely to offer contaminated food. Some street vendors may offer to peel the fruit, but the cleanliness of the merchant's hands is still suspect. No raw fruit or vegetables should be eaten unless it can be peeled and the traveller peels it him/herself. Don't eat lettuce, raw vegetables and cut-up fruit salad. Milk and dairy products are not safe unless they have been pasteurised, as heating destroys the organisms. Travellers should avoid any dish prepared in advance and allowed to stand, such as hot sauces sitting on tables in open containers. All cooked food must be served hot. Meat must be cooked. Raw/underdone meat and fish MUST BE AVOIDED.

DO NOT DRINK TAP WATER! Even the amount used to wet a toothbrush contains large numbers of organisms. ALWAYS REFUSE ICE - it is made from tap water! Tea and coffee (not iced!) are low risk. Canned soft drinks are safe , as long as the traveller opens the can. If tap water is the only source, boil for 5 - 7 minutes and let it cool down spontaneously.


This is a systemic bacterial disease contracted when food or water contaminated with faeces or urine of a patient or carrier is ingested. Uncooked foods like salads are often the carrier—and particularly in Asia. It may cause fever, headache and constipation (more commonly than diarrhoea).

Intestinal haemorrhage or perforation may occur in untreated cases – which can lead to the death of the patient. Inoculation with typhoid injection is advised for international travellers – especially if they are likely to be exposed to unsafe food or water. The inoculation provides immunity for three years.


This explanation is offered because travellers from South Africa may be regarded as travellers from 'Africa' and that could mean that you will be required to show proof of immunisation at your destination country.

Travellers from South Africa do NOT require such proof when entering a non-yellow fever country, but you cannot argue with a health official at a foreign airport when he insists that you have entered from 'Africa' and must produce a certificate… (India, Pakistan, Sri Lanka, Maldives, Mozambique are examples of destinations that have requested such proof – when, in fact, it is not required by the WHO). A flight path that includes a stop in central Africa may justify a request for proof of inoculation.

Yellow fever is endemic in the tropics of Africa and America – it is a virus transmitted by a mosquito. The disease is a much bigger problem in Africa than in America. The disease is responsible for about 200 000 cases and about 30 000 deaths annually in Africa alone! The mosquito flourishes in human habitations especially under slum conditions and is prevalent in the large urban informal settlements in tropical Africa. The closest country to South Africa where the disease occurs is Zambia. Argentina has been added to the list of countries where yellow fever occurs.

A single 0.5 ml subcutaneous inoculation provides excellent immunity in over 95% of recipients providing long-lasting immunity, probably for a lifetime. International travel regulations, however, demand that boosters be administered every 10 years. Travel into countries where yellow-fever occurs requires a compulsory inoculation. Some border officials may refuse entry without such proof, others will insist upon 'on site inoculation' and, possibly, quarantine incarceration. South Africa will insist upon proof of inoculation upon return if you have visited a yellow fever country.

The risk of infection can be minimised by taking general measures to prevent or reduce mosquito bites, including avoiding being outdoors at dusk and in the early evening. Wearing of long trousers and long-sleeved shirts, using of mosquito repellents on exposed skin, and sleeping in screened rooms or under netting is also advised.