Hong Kong Health Overview

There are no specific health risks associated with travel to Hong Kong. Food and water are safe, although visitors should consider only drinking bottled water for the first few days of their stay. Take precautions against mosquito bites, as there is a risk of Dengue fever. Hong Kong's health facilities are first class, but expect to pay cash. Medical insurance is advised. Cases of bird flu have been reported and although the risk for travellers is low, all close contact with caged, domestic and wild birds should be avoided, and all poultry and egg dishes well cooked.

Influenza

Cause: Influenza viruses of types A, B and C; type A occurs in two subtypes (N1 and N2). Type A viruses cause most of the widespread influenza epidemics; type B viruses generally cause regional outbreaks, and type C are of minor significance for humans. Influenza viruses evolve rapidly, changing their antigenic characteristics, so that vaccines need to be modified each year to be effective against currently circulating influenza strains. Other types and subtypes of influenza viruses occur in animals and birds; transmission and reassortment between species may give rise to new subtypes able to infect humans. Transmission: Airborne transmission of influenza viruses occurs particularly in crowded enclosed spaces. Transmission also occurs by direct contact with droplets disseminated by unprotected coughs and sneezes and contamination of the hands. Nature of the disease: An acute respiratory infection of varying severity, ranging from asymptomatic infection (e.g. causes no symptoms) to fatal disease. Initial symptoms include fever with rapid onset, sore throat, cough and chills, often accompanied by headache, coryza, myalgia and prostration. Influenza may be complicated by viral or more often bacterial pneumonia. Illness tends to be most severe in the elderly and in young children. Death resulting from influenza occurs mainly in the elderly and in individuals with pre-existing chronic diseases.
Geographical distribution: Worldwide. In temperate regions, influenza is a seasonal disease occurring in winter: it affects the northern hemisphere from November to March and the southern hemisphere from April to September. In tropical areas there is no clear seasonal pattern, and influenza may occur at any time of the year. Risk for travellers: Travellers, like local residents, are at risk in any country during the influenza season. Travellers visiting countries in the opposite hemisphere during the influenza season are at special risk, particularly if they have not built up some degree of immunity through regular vaccination. The elderly, people with pre-existing chronic diseases and young children are most susceptible. Prophylaxis (protective treatment): Vaccination before the start of the influenza season. However, vaccine for visitors to the opposite hemisphere is unlikely to be obtainable before arrival at the travel destination. For travellers in the highest risk groups for severe and complicated influenza who have not been or cannot be vaccinated, the prophylactic use of antiviral drugs such as zanamivir and oseltamivir is indicated in countries where they are available. Amantidine and rimantidine may also be considered. Precautions: Whenever possible, avoid crowded enclosed spaces and close contact with people suffering from acute respiratory infections. Source: WHO.

Hepatitis A

Cause: Hepatitis A virus, a member of the picornavirus family. Transmission: The virus is acquired directly from infected persons by the faecal-oral route or by close contact, or by consumption of contaminated food or drinking water. There is no insect vector or animal reservoir (although some non-human primates are sometimes infected). Nature of the disease: An acute viral hepatitis with abrupt onset of fever, malaise, nausea and abdominal discomfort, followed by the development of jaundice a few days later. Infection in very young children is usually mild or asymptomatic (e.g. causes no symptoms); older children are at risk of symptomatic disease. The disease is more severe in adults, with illness lasting several weeks and recovery taking several months; case-fatality is greater than 2% for those over 40 years of age and 4% for those over 60. Geographical distribution: Worldwide, but most common where sanitary conditions are poor and the safety of drinking water is not well controlled. Risk for travellers: Non-immune travellers to developing countries are at significant risk of infection. The risk is particularly high for travellers exposed to poor conditions of hygiene, sanitation and drinking water control. Prophylaxis (protective treatment): Vaccination. Precautions: Travellers who are non-immune to hepatitis A (i.e. have never had the disease and have not been vaccinated) should take particular care to avoid potentially contaminated food and 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.