With all the publicity it's getting you'd think ebola was the tropical disease most likely to cause future health problems in the United States--not by a long shot. Other tropical diseases pose much more realistic threats because they are spread by insects that can't be quarantined.
Scientists at the CDC worry that these tropical diseases are gaining a foothold in local insect populations posing a huge problem in the near future. What's most worrisome to researchers is how little is known about these infections.
Here are three of the biggest threats:
Chagas Disease
Chagas disease is a parasitic disease spread by the blood-sucking kissing bug. With the parasite, Trypanosoma cruzi, in its gut first it bites you and then poops into the wound. It can also be contacted by rubbing, carrying the poop to the eyes or mouth. It likes to bite people's faces at night mostly around the mouth because they're attracted to exhaled breath. Campers beware! Found near river banks, and areas of warmth and dampness. It can also be spread from mother to infant, and through contaminated blood or organ donations. The blood supply has been screened for T. cruzi since 2007.
"Chagas disease is particularly insidious because it may not cause symptoms initially. But eventually, according to the U.S. Centers for Disease Control and Prevention, 20 to 30 percent of infected people develop serious heart or digestive problems, some of which can be debilitating and life-threatening without treatment. An estimated six million to eight million people worldwide live with Chagas disease, which causes about 50,000 deaths a year," according to the World Health Organization.
Rare in the U.S, big pharmaceutical companies are not motivated to research and develop drugs for prevention and treatment, although the CDC estimates that it affects approximately 300,000 to a million people in the U.S.
Endemic in Latin America, kissing bugs have been found in the southern states, especially in east Texas according to an article published earlier this month in the American Journal of Tropical Medicine and Hygiene. It has also been found in Oklahoma, Louisiana, Mississippi, and Arkansas. Most recently, a study this year found that many dogs in shelters carry T. cruzi, serving as another reservoir that brings the disease into even closer contact with humans.
The CDC has sought to raise awareness and improve diagnostic tools for Chagas. It doesn't mandate that states report cases of Chagas, but four states do, including Texas and California.
Drugs currently used to treat the disease--the antiparasitics benznidazole and nifurtimox--are not approved by the U.S. Food and Drug Administration and need to be obtained directly from the CDC. DONDi, Drugs for Neglected Disease initiative, is working to find a vaccine.
Chikungunya
Chikungunya is a mosquito-transmitted disease producing fever, joint and muscle pain, headache, lethargy, and rash. Rarely fatal, it can lead to chronic pain and arthritis. The elderly and females seem to be most affected.
Endemic in the Caribbean but new to the United States, as of the end of last month there were 1,627 cases reported so far this year, most of them in Florida. Not nationally reportable, last month health-care providers throughout Texas were told to consider chikungunya infections for patients whose illness was consistent with the disease. The Texas Medical Association urged doctors to determine if these patients had traveled to areas with known outbreaks.
"What happens is that people come back from the Caribbean to Florida with the virus in their blood," explains Stephen Higgs, director of the Biosecurity Research Institute at Kansas State University, in Manhattan. "Local mosquitoes feed on them, and then develop an infection. Then those mosquitoes bite someone else."
Carried by two types of mosquitoes, the yellow fever mosquito and the Asian tiger mosquito, so far--lucky for us--the virus strain circulating in the Americas is primarily spread by the less-common yellow fever mosquito, Aedes aegypti.
But if the virus mutates and starts to prefer the Asian tiger mosquito that's a problem since the tiger has a much wider geographical range in the United States, probably as far north as New Jersey, New York, and Pennsylvania. A further problem is that the tiger is an all-day biter. Researchers worry that given these ramifications, in time chikungunya could become as common in the US as the West Nile virus.
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