Dr. Barry Dworkin

Originally published in The Ottawa Citizen January 12, 2004
Original Title: Have needle, will travel

Southern vacations beckon during the long winter months. Depending on the destination, there may be certain vaccination and malaria- prevention measures that will reduce the traveller’s risk of debilitating disease. Many, however, wait too long before they visit a doctor for a travel medicine consultation.

Unfortunately, if the consultation is left for the week before departure, it is too late to vaccinate against infectious diseases other than malaria. Many of the vaccines require several weeks or even months to stimulate an antibody response sufficient to provide immunity.

Aside from the routine childhood vaccinations, there are specific vaccines and malaria medications recommended for certain countries. The travel vaccines include hepatitis A and B, typhoid fever, Japanese encephalitis, cholera, yellow fever, Lyme disease and meningitis. Recommendations depend on the destination, duration of stay, whether travellers will remain in urban areas or in the countryside, and the season, among other factors.

A common erroneous assumption made by people who travel to their country of origin is that they are immune to the endemic diseases. For example, a person from India may assume they are immune to hepatitis A or B or malaria because they lived in an area where the disease was present. Blood tests can determine if there was previous exposure and the person’s immunity status. If they are not immune, they are at risk.

What are the effects of these diseases?

Hepatitis A and B are contagious liver infections. Hepatitis A risk increases in countries with contaminated water supplies from poor sanitation systems. Transmission occurs through direct contact with infected people who do not wash their hands after a bowel movement and through ingestion of contaminated water or food, especially uncooked shellfish. About 25 per cent of infected adults require hospitalization. The overall mortality rate is 0.1 to 0.3 per cent, rising to more than 1.8 per cent after age 50.

Hepatitis B’s fatality rate is about one to two per cent and increases with age. Transmission occurs through sexual activity, contaminated needles, tattooing, breastfeeding, toothbrushes and razors, among other modes. Fifty per cent of adults and 90 per cent of children develop symptoms (anorexia, abdominal pain, jaundice, and vomiting) that can persist for three months. About 300 to 350 million people worldwide are chronic carriers.

Six to 10 per cent of infected adults and 90 to 95 per cent of infected infants become chronic carriers. Newborn and infant exposure to this virus can result in liver cancer later in life, nine times out of 10.

Typhoid fever (salmonella typhi) is transmitted through food contaminated by feces or urine of infected people or carriers. It causes severe illnesses including nausea, vomiting, bloody diarrhea, fever and dehydration. This bacterial illness is endemic to Africa, Asia and Central and South America. Fatality rates in untreated people are 16 per cent, compared to one per cent if treated.

Japanese encephalitis (brain inflammation), a mosquito-borne viral infection, is the leading cause of encephalitis in Asia, about 50,000 cases per year. The risk is low for North American travellers to resort or city regions, about one per million. Travel to the countryside can increase the risk to one in 5,000. One case of encephalitis occurs for every 50 to 300 infections. Ten to 25 per cent will die of encephalitis and 50 per cent will suffer brain damage.

Yellow fever is another mosquito-borne viral infection that leads to gastrointestinal hemorrhage, jaundice, cardiovascular instability, kidney failure and heart muscle inflammation. It has a 50-per-cent fatality rate. It is endemic only to sub-Saharan Africa and tropical South America between latitudes 15 degrees north and 10 degrees south.

Cholera, found in contaminated food and water, is a water-borne bacterial illness that causes profuse diarrhea and dehydration. Left untreated, 50 per cent will die. Prompt treatment can reduce the rate to less than one per cent.

Lyme disease is a deer-tick-borne illness localized to northeastern, mid-Atlantic, upper north-central and northwestern regions of the United States. Left untreated it can lead to debilitating musculoskeletal, cardiac or central nervous system complications.

Every country requires a thorough evaluation of its endemic diseases and the risk of contracting them. The International Association for Medical Assistance to Travellers (IAMAT) is an excellent resource used by health professionals and travellers alike for just this purpose. It will help you prepare a vaccination list and schedule ahead of time.

Once you register on their website (www.iamat.org) you will be sent easy-to-use documentation sheets such as the World Immunization Chart, World Malaria Risk Chart, How To Protect Yourself Against Malaria and the World Climate Chart. The sheets are available as free PDF-file downloads.

Your travel plans should include an in-depth evaluation of the medical risks. Consult your doctor or any of the travel medicine clinics. Travel medicine consultation is not an OHIP-covered service. Consider it a part of your travel expenses. It is well worth the cost.