Laos Health Overview

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Those planning to travel to Laos should seek medical advice about vaccinations and endemic diseases at least three weeks prior to departure. There have been Avian Influenza poultry outbreaks in northern Laos provinces. Malaria exists throughout the country except in Vientiane, and typhoid and cholera occur in some areas. A typhoid vaccine is recommended for all travellers except short-term business travellers who will restrict their meals to major restaurants and hotels. Other risks include Hepatitis E, plague, dengue fever, and Schistosomiasis if swimming in the Mekong River. Travellers' diarrhoea is a problem for many visitors; only drink bottled water and avoid dairy products, uncooked meat and fish, salads and unpeeled fruit. Medical care in Vientiane is extremely basic and outside the capital there are no reliable facilities to deal with medical emergencies. Medical evacuation is difficult to organise and very expensive. Travellers are advised to take out comprehensive medical insurance, and those who have an unstable medical condition should consider not travelling to Laos. A yellow fever certificate is required by all entering from an infected area. Bird flu has been detected in poultry and wild birds, and the first case of human infection was confirmed in February 2007; however the risk is still low for travellers, but contact with domestic, caged and wild birds should be avoided and poultry and egg dishes well cooked.

View information on diseases: Typhoid fever , Schistosomiasis (bilharzia), Plague , Malaria , Hepatitis E , Dengue Fever , Cholera

Typhoid fever

Cause: Salmonella typhi, the typhoid bacillus, which infects only humans. Similar paratyphoid and enteric fevers are caused by other species of Salmonella, which infect domestic animals as well as humans. Transmission: Infection with typhoid fever is transmitted by consumption of contaminated food or water. Occasionally direct faecal-oral transmission may occur. Shellfish taken from sewage-polluted beds are an important source of infection. Infection occurs through eating fruit and vegetables fertilized by night soil and eaten raw, and milk and milk products that have been contaminated by those in contact with them. Flies may transfer infection to foods, resulting in contamination that may be sufficient to cause human infection. Pollution of water sources may produce epidemics of typhoid fever, when large numbers of people use the same source of drinking water. Nature of the disease: Typhoid fever is a systemic disease of varying severity. Severe cases are characterized by gradual onset of fever, headache, malaise, anorexia and insomnia. Constipation is more common than diarrhoea in adults and older children. Without treatment, the disease progresses with sustained fever, bradycardia, hepatosplenomegaly, abdominal symptoms and, in some cases, pneumonia. In white-skinned patients, pink spots (papules), which fade on pressure, appear on the skin of the trunk in up to 50% of cases. In the third week, untreated cases develop additional gastrointestinal and other complications, which may prove fatal. Around 2-5% of those who contract typhoid fever become chronic carriers, as bacteria persist in the biliary tract after symptoms have resolved. Geographical distribution: Worldwide. The disease occurs most commonly in association with poor standards of hygiene in food preparation and handling and where sanitary disposal of sewage is lacking. Risk for travellers: Generally low risk for travellers, except in parts of north and west Africa, in south Asia and in Peru. Elsewhere, travellers are usually at risk only when exposed to low standards of hygiene with respect to food handling, control of drinking water quality, and sewage disposal. Prophylaxis (protective treatment): Vaccination. Precautions: Observe all precautions against exposure to foodborne and waterborne infections. Source: WHO.

Schistosomiasis (bilharzia)

Cause: Several species of parasitic blood flukes (trematodes), of which the most important are Schistosoma mansoni, S. japonicum and S. haematobium. Transmission: Infection with bilharzia occurs in fresh water containing larval forms (cercariae) of schistosomes, which develop in snails. The free-swimming larvae penetrate the skin of individuals swimming or wading in water. Snails become infected as a result of excretion of eggs in human urine or faeces. Nature of the disease: Chronic conditions in which adult flukes live for many years in the veins (mesenteric or vesical) of the host where they produce eggs, which cause damage to the organs in which they are deposited. The symptoms of bilharzias depend on the main target organs affected by the different species, with S. mansoni and S. japonicum causing hepatic and intestinal signs and S. haematobium causing urinary dysfunction. The larvae of some schistosomes of birds and other animals may penetrate human skin and cause a self-limiting dermatitis, "swimmers itch". These larvae are unable to develop in humans. Geographical distribution: S. mansoni occurs in many countries of sub-Saharan Africa, in the Arabian peninsula, and in Brazil, Suriname and Venezuela. S. japonicum is found in China, in parts of Indonesia, and in the Philippines (but no longer in Japan). S. haematobium is present in sub-Saharan Africa and in eastern Mediterranean areas. Risk for travellers: In endemic areas, travellers are at risk to bilharzias while swimming or wading in fresh water. Prophylaxis (protective treatment): None. Precautions: Avoid direct contact (swimming or wading) with potentially contaminated fresh water in endemic areas. In case of accidental exposure, dry the skin vigorously to reduce penetration by cercariae. Avoid drinking, washing, or washing clothing in water that may contain cercariae. Water can be treated to remove or inactivate cercariae by paper filtering or use of iodine or chlorine. Source: WHO.

Plague

Cause: The plague bacillus, Yersinia pestis. Transmission: Plague is a zoonotic disease affecting rodents and transmitted by fleas from rodents to other animals and to humans. Direct person-to-person transmission does not occur except in the case of pneumonic plague, when respiratory droplets may transfer the infection from the patient to others in close contact. Nature of the disease: Plague occurs in three main clinical forms: Bubonic plague is the form that usually results from the bite of infected fleas. Lymphadenitis develops in the drainage lymph nodes, with the regional lymph nodes most commonly affected. Swelling, pain and suppuration of the lymph nodes produces the characteristic plague buboes. Septicaemic plague may develop from bubonic plague or occur in the absence of lymphadenitis. Dissemination of the infection in the bloodstream results in meningitis, endotoxic shock and disseminated intravascular coagulation. Pneumonic plague may result from secondary infection of the lungs following dissemination of plague bacilli from other body sites. It produces severe pneumonia. Direct infection of others may result from transfer of infection by respiratory droplets, causing primary pulmonary plague in the recipients. Without prompt and effective treatment, 50-60% of cases of bubonic plague are fatal, while untreated septicaemic and pneumonic plague are invariably fatal. Geographical distribution: There are natural foci of plague infection of rodents in many parts of the world. Wild rodent plague is present in central, eastern and southern Africa, south America, the western part of north America and in large areas of Asia. In some areas, contact between wild and domestic rats is common, resulting in sporadic cases of human plague and occasional outbreaks. Risk for travellers: Generally low. However, travellers in rural areas of plague-endemic regions may be at risk, particularly if camping or hunting or if contact with rodents takes place. Prophylaxis (protective treatment): A vaccine effective against bubonic plague is available exclusively for persons with a high occupational exposure to plague; it is not commercially available in most countries. Precautions: Avoid any contact with live or dead rodents. Source: WHO.

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.

Hepatitis E

Cause: Hepatitis E virus, which has not yet been definitively classified (formerly classified as Caliciviridae). Transmission: Hepatitis E is a waterborne disease usually acquired from contaminated drinking water. Direct faecal-oral transmission from person to person is also possible. There is no insect vector. It is suspected, but not proved, that hepatitis E may have a domestic animal reservoir host, such as pigs. Nature of the disease: The clinical features and course of the disease are generally similar to those of hepatitis A. As with hepatitis A, there is no chronic phase. Young adults are most commonly affected. In pregnant women there is an important difference between hepatitis E and hepatitis A: during the third trimester of pregnancy, hepatitis E takes a much more severe form with a case-fatality rate reaching 20%. Geographical distribution: Worldwide. Most cases, both sporadic and epidemic, occur in countries with poor standards of hygiene and sanitation. Risk for travellers: Travellers to developing countries may be at risk of hepatitis E when exposed to poor conditions of sanitation and drinking water control. Prophylaxis (protective treatment): None. Precautions: Travellers should follow the general conditions for avoiding potentially contaminated food and drinking-water. 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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