Originally published in the Ottawa Citizen, July 19, 2004
Original Title: Preventing malaria when you travel

Hippocrates (460?-377 BC) described it in his written observations. Ancient Chinese, Egyptian and Middle Eastern cultures refer to this disease. Outbreaks often coincide with warfare, mass migrations and other societal disruptions.  The British blamed “bad air” in the mid 1800’s India for a disease that killed many of their nationals. This mala aria (from the Italian) has killed more soldiers in the 20^th century wars than bullets. The World health Organization reported 270 million worldwide cases and one million deaths in 1998.

Contrary to popular belief, malaria did exist in the Americas and arrived here as early as 1493. High risk areas for malaria include Central and South America, Haiti and the Dominican Republic, Southeast Asia, Africa, India, and the Middle East.

In 1638, Spanish Jesuit missionaries brought South American cinchona bark back to Europe. The bark, the first treatment for malaria contains quinine. Tonic water was used as means to make the drug more palatable.

Malaria spreads by the bite of an infected Anopheles mosquito. Once the parasite enters the blood stream it heads to the liver to reproduce. The red blood cells will carry the parasite that can infect more mosquitoes if you are bitten.

Over 80 percent of people with malaria will develop chills, sweats, headaches, fever, muscle aches and joint pain. Others in addition may experience a loss of appetite, nausea, vomiting and abdominal pain.

It can take ten to 28 days after the mosquito bite to develop symptoms. Indeed, malaria can appear in as little as eight days after a bite or one year later depending upon which of the four common types of malaria parasite is involved.

How can you assess your risk of contracting malaria?

Your doctor will need to know exactly where you will be traveling and your accommodations. This includes the specific cities or regions within the country. The destinations’ elevation is important because malaria transmission is rare 2,000 metres above sea level.

Many organizations monitor malaria. The country’s malaria risk can vary throughout the year and with the seasons. Some areas may be devoid of malaria while there may be pockets of severe infestation.

If you are a night owl and spend time outdoors, beware; the Anopheles mosquito feeds from dusk to dawn. Even as little as an hour of outdoor nighttime exposure can lead to infection.

People commonly wait too long before consulting their doctor for travel vaccines and malaria prevention. Certain vaccines and malaria medications must be given weeks to months before you travel so that they can provide maximum protection. Visit your doctor at least six weeks before your departure.

The choice of antimalarial medications will be linked to your destination and the latest information from travel medicine advisory centres. Although antimalarial drugs can significantly reduce the chance of infection, they are not foolproof. Furthermore, it is mandatory that the medications be taken exactly as prescribed. If not, it will provide an opportunity for the parasite to infect you even after you have returned home. Indeed, there are many endemic areas that have specific patterns of antimalarial drug resistance

Prudent malaria prevention actions include:

• Curtail nighttime activities. Wear long sleeve shirts and pants when outside at night.
• Insect repellents like DEET in concentrations of approximately 30 percent for adults and ten percent for children should be used on the hands and face and other exposed skin. Spray it on clothes as well. Reapply every three to four hours.
• Check your accommodations to make sure they have screens over their doors and windows or make sure they are shut tight at night. If possible choose a room that is air-conditioned since the mosquito likes heat.
• Drape the bed with mosquito netting permeated with the insect repellent permethrin. It can reduce the mosquito attack rate by 97 percent
• Stick to your medication schedule and complete the course even after you return home.

Consult your doctor immediately if you develop a fever after returning home.

For more information visit these sites:

CDC Travelers’ Health Information: www.cdc.gov/travel
Malaria Foundation International: www.malaria.org
International Association for Medical Assistance to Travellers: www.iamat.org

Related articles:

1. A look at an experimental malaria vaccine
2. Malaria risk when traveling
3. Malaria prevention when traveling

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.

Related articles:

1. Don’t let malaria put the bite on your travels
2. Tropical disease prevention prior to travel
3. Why Children will suffer the most

Originally published in The Ottawa Citizen December 3, 2002
Original Title: Cruise Ship: The perils of adult daycare

Recent reports of three cruise ship outbreaks of viral diarrheal illness (gastroenteritis) bring into focus how easily infections spread. Each ship had hundreds of passengers who fell ill. Carnival’s cruise ship Fascination, Disney’s Magic and Holland America’s Amsterdam all underwent extensive decontamination procedures.

Florida’s Department of Health and Atlanta’s Centers for Disease Control (CDC) both think that Norwalk virus is the culprit. Food borne disease is a significant cause of gastroenteritis. The CDC tabulated approximately 76 million diarrheal illnesses, 325,000 hospitalizations, and 5000 deaths each year in the United States based upon surveillance data from multiple sources.

Norwalk virus is the one of the most common causes of gastroenteritis in children and adults. The virus grows within the gastrointestinal tract. It is spread by fecal-oral route. As the term implies, ineffective hand washing after a bowel movement leaves viral residue on the hands. This residue spreads by contact. When another person touches the residue-laden object or hand and brings their hand to their mouth, voila, the porcelain throne becomes an important piece of furniture.

Indeed, passengers disembarking at Caribbean and Central American ports are exposed to the local food and water supply. Although most travelers are aware of the risks it is difficult to ensure complete protection from illness. With thousands of passengers on cruise ships, the potential for viral propagation through this ‘captive’ population is great.

The dense passenger population on cruise ships is akin to the children’s daycare scenario. The Norwalk virus causes most school and daycare-based cases of gastroenteritis. Soiling of clothes, lack of handwashing and close physical contact between children with less than perfect hygiene habits are fertile breeding grounds for this disease.

Cruise ships are adult playgrounds with unlimited buffets and drinks, numerous contact sports and activities, close contact between people, and ports of call to towns and cities with potential sources of food and water contamination. These factors contribute to an increase in overall risk of infection. Indeed, it only requires one infected person among the passengers to contaminate all these open and available sources.

According to Holland America, the decontamination process involves everything passengers and crew touch. All items touched by people need to be cleansed. A spokesperson for Holland America stated “The cleaning crew had to steam clean 300,000 square feet of carpet, replace 4,000 pillows and hand scrub every dish, eating utensil, glass and poker chip. Places where passengers put their hands, such as door handles, chair armrests, railings and tabletops also were scrubbed with a strong chlorine solution for several minutes, the only way to kill the virus. Even the ship directory in every cabin was replaced.”

Despite this due diligence, the Norwalk virus continues to be a problem. The recent closure of several Eastern Ontario hospitals attests to the difficulties controlling and limiting the spread of this virus.

The Norwalk virus can cause either a mild fever with watery diarrhea or a more severe fever with vomiting, headache, muscle ache and fatigue. Once infected, the virus will incubate about 24 to 48 hours before the symptoms begin. Stomach cramps and nausea are the first to appear starting gradually or hit full force. Vomiting follows thereafter. A low-grade fever of 38.3 to 38.9ºC (101 to 102ºF) occurs in approximately one-half of cases. The infection lasts about 48 to 72 hours. Infected persons typically have non-bloody, watery diarrhea with four to eight bowel movements over a 24 hour period. There is usually no mucous seen in the stools because the walls of the small intestine do not become inflamed. Recovery is usually rapid. Children in particular are at risk for dehydration.

The Norwalk virus is shed in the stools. This shedding occurs over the first 24 to 48 hours after the illness. It is rarely detected beyond 72 hours after the onset of vomiting or diarrhea.

If you are planning a cruise vacation or any vacation for that matter, there may be some instances and locales where hand washing facilities may be substandard or unavailable.

Judicious use of a particular product can reduce your risk of gastroenteritis and other infections in combination with the usual travel precautions. Purell(r) is an alcohol gel disinfectant available in a pump or small squeeze tube format. The gel’s alcohol concentration is great enough to kill most viruses and bacteria. It does not require water to rinse or wash the hands. The gel dries in about ten to 20 seconds after its application. It can be used as many times as is necessary. Carry it with you at all times.

As thorough as the ship decontamination efforts seem to be, will they reduce future ship-wide viral outbreaks? Although the cruise lines have done their best to reduce the risk, it is impossible to screen each passenger for disease. Further not all people are equally effective with hygiene procedures.

Ultimately, the onus is on travelers to do their best to reduce their risk of travel-related illnesses.

© Dr. Barry Dworkin 2002

Related articles:

1. Norovirus outbreaks on cruise ships
2. Children’s eye diseases spread quickly
3. The science of hand washing