Chances are, when you go to less-developed lands, you’re most concerned about avoiding traveler’s diarrhea (try chewing two tablets of bismuth subsalicylate — Pepto-Bismol or generic versions — with each meal). But to help assure a medically uneventful trip, you’d be wise to remain alert to avoiding various bacterial, parasitic, viral and fungal infections that enter through the skin and are rarely encountered in the United States.

Cutaneous larva migrans, an extraordinarily itchy infection by the larval stage of a hookworm, is most commonly acquired from dog or cat feces deposited on beaches of the Caribbean and Southeast Asia, Dr. Keystone said. Best protection: Don’t walk barefoot on the beach; wear water shoes, not sandals. The infection, should it occur, is now easily treated with oral antiparasitic drugs like albendazole or ivermectin.

Some infections are transmitted by the bite of mosquitoes, like malaria, dengue fever and filariasis, the risk of which often can be greatly reduced by diligent use of the insect repellents that can protect against various disease transmitters.

In an interview, Dr. Keystone, who wrote the chapter on skin and soft-tissue infections in returned travelers in the C.D.C.’s travel health guide, called the Yellow Book, urged the use of either Icaridin (picaridin) or 50 percent Deet, both of which can provide up to 10 hours of protection. He said Icaridin is better tolerated; it smells better and is not greasy.

Most important, he said, is to use the repellent regularly, especially during the hours mosquitoes are most active, and apply it after putting on sunscreen, not before. These repellents can also protect against tick bites, which in this country and elsewhere can carry Lyme disease, among other miseries.

Also helpful is applying permethrin to one’s clothing and gear, including pants, socks, boots and tent. Or purchase pre-treated clothing. The protection will last through multiple washings.

I once returned from a safari in Kenya with intensely itchy chigger bites on my legs, acquired while standing in tall weeds at the edge of a lake to photograph flamingoes. These tiny larvae, which hang out on leaves and branches, may also carry infectious bacteria that make people very sick, Dr. Keystone said.