Need another reason to hate mosquitos? One word: chikungunya. Like yellow fever, chikungunya is a virus carried by a gluttonous mosquito that has already dined on an infected person. The mosquito doesn't get sick but happily hosts the virus, nurturing it to greater strength before depositing some of the virus in the next victim.

Although widespread in tropical areas throughout the world, chikungunya is thankfully rather rare. You're more likely to be infected with the yellow fever virus or with filariasis, a disease caused by a roundworm that lives in your lymph vessels and tissues. But if you do get chikungunya, watch out. You will get a headache, fever, nausea, and perhaps a rash. The worst effect is sudden pain in the joints, like a severe case of instant arthritis. You aren't likely to die, but your joints can remain stiff for weeks or months after the mosquito bite.

There is no vaccine to prevent chikungunya, nor is there a cure. You just have to ride it out. Better still, you should try to avoid tropical mosquito bites in the first place by wearing clothing that covers most of your skin, by using mosquito nets, by staying in screened-in places, and by applying mosquito repellent with DEET. Or stay away from the tropics entirely and let the virus-free mosquitos of the north woods chew you up.

It was in Tanzania, in 1953, that chikungunya was first officially identified by the world medical community. That is how its name, published in English in 1954, happened to come from the Makonde language of southern Tanzania and northern Mozambique on the east coast of Africa. In Makonde, chikungunde is said to mean "that which folds up" and refers to the crippling of the joints.

Makonde is spoken by nearly a million of the thirty million people of Tanzania and by another 360,000 in Mozambique. It is a Bantu language of the Niger-Congo language family. No other word of Makonde has entered English.

The World in So Many Words, by Allan A. Metcalf. Copyright © 1999 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.