Spread of malaria, dengue fever puts them at top of watch list

Avian flu and SARS made headlines last year, but malaria and dengue fever should be on travelers’ radar for 2005, experts say.

That doesn’t mean tourists should let down their guard against bird flu or severe acute respiratory syndrome, both of which may reemerge, travel medicine experts say. But several cite malaria and dengue fever as more likely threats.

Top health concerns in 2005:

Malaria: Until they travel overseas, most Americans don’t think much about the mosquito-borne illness, says Dr. Phyllis Kozarsky, senior travelers’ health consultant for the U.S. Centers for Disease Control and Prevention and a professor of medicine at Emory University in Atlanta.

“With malaria, we are so sheltered in this country we don’t realize there are 300 million cases in the world per year,” she says.

“We are talking about a disease that has reemerged,” she says, citing places where malaria had been eradicated but has returned in strains that resist many antimalarial drugs. One strain, Plasmodium falciparum, has developed resistance to nearly all antimalarials, including chloroquine (Aralen), mefloquine (Lariam) and quinine, according to the CDC.

Symptoms usually appear nine to 14 days after the bite and include fever, headache, vomiting and others that mimic the flu. The disease is common in tropical and subtropical areas, mainly parts of Central and South America, Hispaniola (the island composed of Haiti and the Dominican Republic), Africa, Asia, the Middle East and Oceania, according to the CDC.

In November, the CDC received reports of two U.S. travelers to the Dominican Republic who contracted the disease. About 90% of the deaths occur in sub-Saharan Africa, mostly among young children, the World Health Organization says.

Dengue fever: This disease, also mosquito-borne, is reemerging as the geographic reach of infected mosquitoes is spreading, Kozarsky says. Dengue fever is endemic in more than 100 countries, mostly tropical destinations in North and South America, the Caribbean, the South Pacific, Asia and Africa, according to the CDC. Cases have been documented in Texas, however, and an outbreak occurred in Hawaii in 2001.

WHO estimates that from 1995 to 2001, the annual number of cases in the Americas doubled to 600,000.

Symptoms include fever and chills, severe headache and joint and muscle pain. Vomiting, nausea and rash can also occur.

“It feels like flu symptoms,” Kozarsky says, “but it is not respiratory. You feel like your bones are all broken.”

An estimated 50 million to 100 million cases occur worldwide each year, and of those, up to 500,000 are the most severe form, dengue hemorrhagic fever, in which patients can go into shock and die.

“I think everybody is a little bit more concerned about dengue, and we are seeing more and more cases in returning travelers,” Kozarsky says.

There is no vaccine, adds Dr. David Freedman, director of the travel health clinic at the University of Alabama at Birmingham. Treatment addresses only the symptoms, such as fever.

“Fortunately for most, it’s not common to be fatal,” he said. “It’s miserable, but severe forms are not common.”

The repeated hurricanes and storms in the Caribbean last year may have increased the spread of dengue fever, says Dr. Jay Keystone, director of the Center for Travel and Tropical Medicine at Toronto General Hospital in Ontario, Canada.

“That’s the current theory as to why we are seeing dengue in places not seen before,” he says, adding that pools of standing water from storms made good breeding grounds.

Keystone and WHO say the mosquitoes that transmit dengue fever bite primarily at dusk and dawn but also throughout the day. (Mosquitoes transmitting malaria commonly bite between dusk and dawn, WHO says.)

Travelers should protect against bites throughout the day and night by wearing protective clothing and applying a DEET-based repellent.

Avian flu: The disease that most recently caused widespread concern among many travelers to Asia seems to have subsided, but travel medicine experts say it’s important to remain wary.

“I don’t know if the word ‘controlled’ can be used,” Kozarsky says. “We are still hearing about bird flocks in various countries that may be infected.”

WHO announced Jan. 14 that it had received reports from Vietnam of six cases, four fatal, of avian flu in humans since mid-December.

Avian flu viruses usually aren’t transmitted among humans, only birds and pigs. Outbreaks of the disease among birds were reported last summer by several Asian countries.

People can get the virus after contact with infected poultry or contaminated surfaces. Symptoms in humans include fever, sore throat, cough and sometimes respiratory distress. Antiviral drugs are used to treat it.

The best advice for travelers now, Kozarsky says, is to look for travel updates on the CDC website, https://www.cdc.gov , and ask your healthcare professional for advice if you’re traveling to areas where the disease has been a problem.

“There’s no vaccine for avian flu,” Freedman says, nor will one likely be available anytime soon.

SARS: Severe acute respiratory syndrome is “a bit of a question mark right now,” Kozarsky says. “No one is sure why it hasn’t reemerged. I think we’ve been lucky.”

During the SARS outbreak in 2003, more than 8,000 people worldwide became sick with the disease, and almost 800 died, according to WHO tallies. China was particularly hard hit with more than 5,000 cases.

In the United States, only eight people had laboratory evidence of a SARS infection, and none died. All had traveled to areas where outbreaks had occurred.

SARS is spread by person-to-person contact, often when an infected person coughs or sneezes, according to WHO. Symptoms include a fever along with headache and body aches. Most people develop pneumonia.

“SARS may rear its head again, but it isn’t going to be a major issue,” Keystone says, adding that public health officials are more aware and are “much more likely to jump on it quickly.”

For updates about specific diseases at destinations worldwide, check the websites of the CDC (mentioned previously) or WHO, https://www.who.int .

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