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There is a risk of malaria throughout the year, and dengue fever outbreaks occur. Cholera outbreaks also occur, but are a low risk to travellers. Visitors should drink bottled or boiled water as a preventative measure. Medical facilities are limited and medications may not be available. Travellers are advised to bring their own personal medical kit and travel insurance should be comprehensive.

View information on diseases: Malaria , Dengue Fever , Cholera

Malaria

General considerations: Malaria is a common and life-threatening disease in many tropical and subtropical areas. It is currently endemic in over 100 countries, which are visited by more than 125 million international travellers every year. Each year many international travellers fall ill with malaria while visiting countries where the disease is endemic, and well over 10,000 fall ill after returning home. Fever occurring in a traveller within three months of leaving a malaria-endemic area is a medical emergency and should be investigated urgently. Cause: Human malaria is caused by four different species of the protozoan parasite Plasmodium: Plasmodium falciparum, P. vivax, P. ovale and P. malariae. Transmission: The malaria parasite is transmitted by various species of Anopheles mosquitoes, which bite mainly between sunset and sunrise. Nature of the disease: Malaria is an acute febrile illness with an incubation period of 7 days or longer. Thus, a febrile illness developing less than one week after the first possible exposure is not malaria. The most severe form is caused by P. falciparum, in which variable clinical features include fever, chills, headache, muscular aching and weakness, vomiting, cough, diarrhoea and abdominal pain; other symptoms related to organ failure may supervene, such as: acute renal failure, generalized convulsions, circulatory collapse, followed by coma and death. It is estimated that about 1% of patients with P. falciparum infection die of the disease. The initial symptoms, which may be mild, may not be easy to recognize as being due to malaria. It is important that the possibility of falciparum malaria is considered in all cases of unexplained fever starting at any time between the seventh day of first possible exposure to malaria and three months (or, rarely, later) after the last possible exposure, and any individual who experiences a fever in this interval should immediately seek diagnosis and effective treatment. Early diagnosis and appropriate treatment can be life-saving. Falciparum malaria may be fatal if treatment is delayed beyond 24 hours. A blood sample should be examined for malaria parasites. If no parasites are found in the first blood film but symptoms persist, a series of blood samples should be taken and examined at 6-12-hour intervals. Pregnant women, young children and elderly travellers are particularly at risk. Malaria in pregnant travellers increases the risk of maternal death, miscarriage, stillbirth and neonatal death. The forms of malaria caused by other Plasmodium species are less severe and rarely life-threatening. Prevention and treatment of falciparum malaria are becoming more difficult because P. falciparum is increasingly resistant to various antimalarial drugs. Of the other malaria species, drug resistance has to date been reported for P. vivax, mainly from Indonesia (Irian Jaya) and Papua New Guinea, with more sporadic cases reported from Guyana. P. vivax with declining sensitivity has been reported for Brazil, Colombia, Guatemala, India, Myanmar, the Republic of Korea, and Thailand. P. malariae resistant to chloroquine has been reported from Indonesia. Geographical distribution: The risk for travellers of contracting malaria is highly variable from country to country and even between areas in a country. In many endemic countries of Latin America and the Caribbean, Asia and the Mediterranean region, the main urban areas, but not necessarily the outskirts of towns, are free of malaria transmission. However, malaria can occur in main urban areas in Africa and India. There is usually less risk of the disease at altitudes above 1,500 metres, but in favourable climatic conditions it can occur at altitudes up to almost 3,000 metres. The risk of infection may also vary according to the season, being highest at the end of the rainy season. There is no risk of malaria in many tourist destinations in South-East Asia, Latin America and the Caribbean. Source: WHO.

Dengue Fever

Cause: The dengue virus - a flavivirus of which there are four serotypes. Transmission: Dengue fever is transmitted by the Aedes aegypti mosquito, which bites during daylight hours. There is no direct person-to-person transmission. Monkeys act as a reservoir host in south-east Asia and west Africa. Nature of the disease: Dengue occurs in three main clinical forms: Dengue fever is an acute febrile illness with sudden onset of fever, followed by development of generalized symptoms and sometimes a macular skin rash. It is known as "breakbone fever" because of severe muscular pains. The fever may be biphasic (i.e. two separate episodes or waves of fever). Most patients recover after a few days; Dengue haemorrhagic fever has an acute onset of fever followed by other symptoms resulting from thrombocytopenia, increased vascular permeability and haemorrhagic manifestations; Dengue shock syndrome supervenes in a small proportion of cases. Severe hypotension develops, requiring urgent medical treatment to correct hypovolaemia. Without appropriate treatment, 40-50% of cases are fatal; with timely therapy, the mortality rate is 1% or less. Geographical distribution: Dengue fever is widespread in tropical and subtropical regions of central and south America and south and south-east Asia and also occurs in Africa; in these regions, dengue is limited to altitudes below 600 metres (2,000 feet). Risk for travellers: There is a significant risk for travellers in areas where dengue fever is endemic and in areas affected by epidemics of dengue. Prophylaxis (protective treatment): None. Precautions: Travellers should take precautions to avoid mosquito bites both during the day and at night in areas where dengue occurs. Source: WHO.

Cholera

Cause: Vibrio cholerae bacteria, serogroups O1 and O139. Transmission: Infection occurs through ingestion of food or water contaminated directly or indirectly by faeces or vomit of infected persons. Cholera affects only humans; there is no insect vector or animal reservoir host. Nature of the disease: An acute enteric (intestine) disease varying in severity. Most infections are asymptomatic (i.e. do not cause any illness). In mild cases, diarrhoea occurs without other symptoms. In severe cases, there is sudden onset of profuse watery diarrhoea with nausea and vomiting and rapid development of dehydration. In severe untreated cases, death may occur within a few hours due to dehydration leading to circulatory collapse. Geographical distribution: Cholera occurs mainly in poor countries with inadequate sanitation and lack of clean drinking water and in war-torn countries where the infrastructure may have broken down. Many developing countries are affected, particularly those in Africa and Asia, and to a lesser extent those in central and south America. Risk for travellers: The risk of cholera is very low for most travellers, even in countries where cholera epidemics occur. Humanitarian relief workers in disaster areas and refugee camps are at risk.
Prophylaxis (protective treatment): Oral cholera vaccines for use by travellers and those in occupational risk groups are available in some countries. Precautions: As for other diarrhoeal diseases. All precautions should be taken to avoid consumption of potentially contaminated food, drink and drinking water. Oral rehydration salts should be carried to combat dehydration in case of severe diarrhoea. Source: WHO.

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