High on List of Vacation Spoilers: Skin Disease : Rashes may develop weeks after a trip’s conclusion. Beware of insects and avoid overexposure to the sun.

Two weeks after the couple had returned from working in a Haitian orphanage, they noticed intolerable itching. Then came the rash that first appeared on their backs and spread around their waists.

The couple eventually sought medical help from Dr. David R. Hill, a travel medicine specialist who diagnosed their problem as scabies, a skin disease caused by a mite that burrows under the skin and lays eggs. Hill speculated that the couple had contracted it through physical contact while working with the people in Haiti. “It can take a bit (of time) for the parasite to burrow,” said Hill, director of the International Travelers Medical Service at the University of Connecticut, Farmington.

This story, Hill said, illustrates what his research has found: that skin problems are an overlooked but not uncommon travel complaint that sometimes don’t show up until after suitcases are unpacked and souvenirs tucked away.

“After traveler’s diarrhea and respiratory problems like sore throats and colds, skin problems are probably next most common,” Hill said. Overall, they account for about 10% of travelers’ problems, his research indicates. In a survey conducted in 1989 and 1990, Hill found that skin rashes were the third most common category of symptoms reported by 515 travelers, outranked only by diarrhea and upper respiratory tract problems.

The itchy parasites experienced by the Haitian orphanage workers are just one example of skin problems that can run the gamut from everyday rashes to life-threatening conditions.

Some species of sand flies prevalent in Asia, Africa and Central and South America can cause another kind of problem. A parasitic disease called leishmaniasis can occur weeks to months after a person is bitten by infected sand flies. Skin sores can develop, according to the Centers for Disease Control and Prevention, and the skin ulcer that results can take a month to heal.

Since there are no vaccines or drugs to prevent sand fly infection, CDC recommends reducing exposure to biting insects by limiting outdoor activities from dusk to dawn, when flies are most active, wearing protective clothing and using insect repellent.

Experts agree on another good piece of advice for keeping insect bites from becoming a major problem: don’t scratch.

Cautious beach-walking is also a good idea. A worm found in dog feces can penetrate the bottom of the feet, causing a condition called cutaneous larva migrans, according to Dr. Michele Barry, co-director of the Tropical Medicine and International Traveler’s Clinic at Yale University. Symptoms include feeling of the worm moving under the skin as it migrates, she said. A prescription drug called thiabendazole, applied topically, can kill the worms.

The beach can present other skin hazards in the form of painful sunburn and skin cancers, with some regions more dangerous than others. So seriously is this potential danger taken that Queensland--Australia’s so-called “Sunshine State”--has begun a public education campaign promoting the use of protective clothing and sunscreen at the beach . . . a reaction to statistics indicating that two of three Australians will eventually develop skin cancer.

Sunlight can wreak other kinds of havoc on the skin, including a condition called “polymorphous light eruption” that primarily afflicts travelers who fly from dark, cold climates in the middle of winter to sun-filled places such as Hawaii or the Caribbean and get a sudden blast of ultraviolet radiation, Barry said. Symptoms of the condition, which may persist for two to three weeks, include tiny papules that look like pimples covering the skin. Barry recommends that travelers suffering from this condition seek medical help. Sometimes topical corticosteroid drugs (such as hydrocortisone) are recommended.

Some medicines can actually increase photo sensitivity to the sun, Barry warned, citing as common examples tetracycline taken for acne or some hypertension medicines to treat high blood pressure. The result could be increased sensitivity to sunlight.

Skin conditions can also be symptoms of other illnesses. For example, dengue fever, a viral disease transmitted by certain mosquitoes in tropical areas of the world, can be accompanied by a rash that appears three to five days after high fever, according to the CDC. Or, Hill said, sometimes the rash and fever occur simultaneously. Often dengue fever is benign, but certain forms, such as dengue hemorrhagic fever, can be fatal.

“The severe form usually occurs (only) with the second episode,” Hill said. But if you suspect dengue fever, he cautioned, seek medical help.

Another skin problem--common with travelers, but much less serious--is superficial fungal infection of the feet that can strike when vacationers are in a warm, humid area and stay active. Excess perspiration, combined with warmth and humidity, can lead to fungal infections, particularly on the feet. “Most over-the-counter products (to combat athletes’ foot) work pretty well,” Hill said.

To minimize the discomfort of skin problems while traveling, Hill and Barry recommend taking along a few first-aid items. On their lists: insect repellents, sun block, topical medications to relieve insect bites, and anti-fungal preparations to combat athlete’s foot infections.