More mosquito-borne misery in the news

Chikungunya cases reported in the United States have more than doubled over the past week. What is this disease, besides being painfully unpronounceable (I can already hear my patients telling me “Doc, I think I have the chicken gumbo disease”)? Chikungunya is caused by a virus spread by mosquitoes. It is endemic to tropical Africa and Asia, but recently has spread rapidly in the Caribbean islands and Central America; all of the reported cases in the US were contracted by visitors to the Caribbean.

The disease isn’t fatal, but is one of those that may make you wish to die–it is characterized by fever and severe muscle and joint pain. The pain usually resolves within a couple of weeks, but may persist longer. There is no treatment for chikungunya except supportive care.

Chikungunya is spread by the bite of the female Aedes aegypti mosquito, which is common throughout the southeastern United States. This mosquito is also responsible for the spread of Dengue fever, which has already become re-established in southern Florida. It is conceivable that chikungunya could be picked up by mosquitoes which bite an infected returning traveller, then bite someone else, thus establishing the disease here.

The best prevention, of course, is to avoid being bitten by infected mosquitoes. DEET works well, and a combination of DEET and permethrin may be even better. There is currently no immunization for chikungunya.

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What is the deadliest creature on earth?

It’s not sharks, or crocodiles, or even man, with our guns and bombs and deadly blow-darts.

Okay, we are second. But, according to Bill Gates’ blog, it is the mosquito, responsible for 725,000 deaths a year, 600,000 from malaria.

Strictly speaking, of course, that makes Plasmodium sp., the malaria-causing parasite transmitted by mosquitoes, the deadliest creature. But Gates is right, mosquito control would save many lives annually.

Thanks to Rachel Carson and others, the cheapest and most effective mosquito pesticide, DDT, is no longer available. My reading suggests that DDT is not as harmful to the environment as we were told in the 60’s and 70’s, and would save many thousands of lives per year.

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