Traveling abroad, particularly to regions with mainly developing nations, may hold certain health risks that are not common in the United States. Therefore travelers need to be aware of these conditions, despite having taken the appropriate travel vaccinations. A vaccine may not always be available for certain diseases whereas in other cases the diseases are short term and unlikely to lead to severe complications thereby not warranting the need for a vaccine. Travel destinations that are growing in popularity these days, and which have significant health risks for travelers, includes those in Asia and particularly South Asia, Southeast Asia and East Asia.
Types of Health Risks
There are various types of health risks in any country, not just Asia. The focus for travelers, however, is infectious diseases which may be widespread in a specific region, transmitted through fairly innocuous routes and for which one does not have any natural immunity or appropriate immunization. Most importantly though, it is diseases which can have severe complications within a short period of time and be life-threatening. Treatments that exist for these diseases may not always be extremely effective. It may also require constant hospitalization and specialist care which may not be accessible in these travel destinations or unaffordable for a traveler. Prevention through vaccination when available, prophylactic medication and conservative measures are therefore the main priority for a traveler.
There are various bacterial forms of gastroenteritis and newly discovered multi-drug resistant species like the NDM-1 (New Delhi metallo-beta-lactamase-1) superbug which may be seen more frequently in Asia. These are major health risks but not specifically for travelers. Most are common pathogens even in developed nations which have become resistant to certain drugs. Caution as a traveler in limiting water intake to reputable brands of bottled brand, eating only in safe food establishments and avoiding contact with unmonitored water sources will usually be sufficient to avoid these diseases. Good personal hygiene is the most effective preventative measure. In most cases these diseases are spread through contaminated food and water and are highly unlikely to be contracted through contact with animals, mosquito or inset bites or transmitted via droplet spread through coughing or sneezing.
Sexually transmitted infections such as HIV, syphilis, gonorrhea, chlamydia, trichomoniasis and genital herpes are found throughout the world and is not usually more widespread in Asia. It has therefore not been included as major health risks for travelers.
Risks by Asian Countries
The risks in these different regions does not differ significantly. However, some types of diseases may be more common that others in specific countries.
- Sri Lanka
Some of the major infectious health risks for travelers to this region includes malaria, dengue fever, filariasis, leishmaniasis, Japanese encephalitis, leptospirosis, polio, measles, avian influenza (H5N1) and rabies.
- East Timor
Some of the major infectious health risks for travelers to this region includes malaria, dengue fever, chikungunya, filariasis, Japanese encephalitis, plague, avian influenza (H5N1), schistosomiasis, leptospirosis, measles and polio.
- Hong Kong
- North Korea
- South Korea
Some of the major infectious health risks for travelers to this region includes malaria, dengue fever, chikungunya, filariasis, Japanese encephalitis, leishmaniasis, plague, tickborne encephalitis, avian influenza (H5N1), measles, schistosomiasis (Schistosoma japonicum), leptospirosis and rabies.
Traveler Disease Information
This is a brief overview of some of the more common infectious diseases that are seen in specific regions within South, Southeast and East Asia.
Avian flu, commonly known as bird flu, is caused by the H5N1 virus. It is rarely seen in humans but is very deadly. Only half of the people infected with the bird flu virus survive the disease. It is found in both wild birds and can occur in domestic birds. The virus is spread by making contact with the bird’s feces, saliva or other secretions. This more often occurs in open air markets where these birds are kept in crowded and unsanitary conditions. Bird flu cannot be contracted through eating the meat of these animals.
Chikungunya is a viral disease caused by an alphavirus and spread by mosquitoes. It is often confused and misdiagnosed as dengue fever due to various similarities with this disease. The main vector is the Aedes aegypti mosquito, but the Aedes albopictus mosquito may also sometimes be involved. These mosquitoes tend to breed in water near sites where humans live. Humans are affected by the virus but certain wild animals like monkeys can serve as a reservoir. Chikungunya can lead to serious complications but is rarely fatal.
Dengue fever is a viral disease caused by one of four serotypes of a flavivirus which is spread by mosquitoes similar to chikungunya. The main vector is the Aedes aegypti mosquito. It may lead to severe complications such as dengue hemorrhagic fever and dengue shock syndrome which are potentially fatal. Dengue fever is more common in urban and semi-urban areas. Dengue hemorrhagic fever is one of the leading causes of death among children in high risk areas.
The two more common types of encephalitis that are of concern to travelers to Asia includes Japanese encephalitis and tick-borne encephalitis. The term encephalitis means inflammation of the brain and is most commonly caused by viruses. Japanese encephalitis is caused by a flavivirus (JEV) that is spread through a bite by mosquitoes carrying the virus. The main vector is the Culex species mosquitoes. Tickborne encephalitis is also caused by a flavivirus (TBEV) which is spread through the bite of an infected tick. The main vector is the Ixodes species tick.
Filariasis is a parasitic infection that mainly affects the lymphatic system of humans. It is caused by a type of parasitic worm known as a nematode. The main filarial nematodes are Wuchereria bancrofti, Brugia malayi and Brugia timori. It is spread through the bite of a number of different species of mosquitoes. Lymphatic filariasis is asymptomatic initially and therefore remains undiagnosed for long periods of time. It causes progressive damage of the lymphatic system.
Leishmaniasis is an infection caused by one of the many types of Leishmania species of protozoal parasites that are spread through the bite of sand flies. It can sometimes be spread through blood transfusions or when IV drug users share a needle. There are two types of leishmaniasis – cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL). Cutaneous leishmaniasis is mainly isolated to the skin and is the more common type. Visceral leishmaniasis may affect any organ in the body.
Leptospirosis is an infection with the Leptospira bacteria which may be contracted through cuts in the skin caused by certain animals like rats, skunks, raccoons, foxes and other vermin. It can also be transmitted through contact with contaminated water and soil that may also enter through the mucous membranes in the body and conjunctiva. Less commonly it occurs through bites or human-to-human transmission. After the acute infectious stage, leptospirosis may lead to septicemia which can be fatal.
Malaria is a disease caused by an infection with the Plasmodium species of protozoal parasites and spread through mosquitoes. It is one of the major health risks across South, Southeast and East Asia although it is not prevalent in every country within this region. The parasite is transmitted through the bite of the infected female Anopheles mosquito. It rapidly destroys red blood cells but also affects the cells of various organs throughout the body. Malaria is potentially fatal and there if no vaccine against it. Certain medication may offer short term protection but the key is reducing exposure to mosquitoes.
Plague is a disease caused by the Yersinia pestis bacteria that is spread though fleas. It is more common with bites of infected fleas on rodents. A less common mode of transmission is handling the tissue of an infected animal. The disease is not common these days but was responsible for the deaths of about one-third of the European population in medieval times when it was known as the Black Death. The bacteria multiples within certain types of immune cells and then spreads throughout the body via the bloodstream. Plague is easily treated but can be fatal if left untreated.
Rabies is an infectious disease caused by the Lyssavirus which is spread through animals. The virus may enter the human host through the saliva of an infected animal, usually as a result of a bite. Rabies is found throughout the world and is more commonly transmitted through dog and bat bites although may other animals may also be infected. Vaccination of animals against rabies has been an effective method to reduce the transmission but there is still a high risk with stray animals. Poor animal control and limited immunization programs in developing nations may place a person at risk.