A green parrot snake climbing on a magenta plant.

The green parrot snake, native to Costa Rica. While their venom is too weak to harm a human, their bite can cause a bacterial infection. Photo © Barb Ignatius, licensed Creative Commons Attribution.

Spiders, scorpions, no-see-ums—it’s enough to give you the willies! Check your bedding before crawling into your bed, which you should move away from the wall if possible. Always shake out your shoes and clothing before putting them on. Repellent sprays and lotions are a must, especially in the rainforest, marshy areas, and coastal lowlands. Bites can easily become infected in the tropics, so avoid scratching. A baking-soda bath can help relieve itching if you’re badly bitten, as can antihistamine tablets, hydrocortisone, and calamine lotion. Long-sleeved clothing and full-length pants help keep insects at bay.

Tiny, irritating no-see-ums (sandflies about the size of a pinpoint, known locally as purrujas) inhabit many beaches and marshy coastal areas; avoid beaches around dusk. They’re not fazed by bug repellent with DEET, but Avon’s Skin-So-Soft works great. Chiggers (coloradillas) inhabit grasslands, particularly in Guanacaste. Their bites itch like hell. Mosquito repellent won’t deter them. Dust your shoes, socks, and ankles with sulfur powder. Sucking sulfur tablets (azufre sublimado) apparently gives your sweat a smell that chiggers find obnoxious. Nail polish apparently works on the bites by suffocating the beasts. Ticks (garrapatas) hang out near livestock. They bury their heads into your skin. Remove them immediately with tweezers—grasp the tick’s head parts as close to your skin as possible and pull gently but steadily.

Tiny, irritating no-see-ums (sandflies about the size of a pinpoint, known locally as purrujas) inhabit many beaches and marshy coastal areas; avoid beaches around dusk. They’re not fazed by bug repellent with DEET, but Avon’s Skin-So-Soft works great. Sandflies on the Atlantic coast can pass on leishmaniasis, a debilitating disease; seek urgent treatment for nonhealing sores.

If stung by a scorpion (alacrán)—not normally as bad as it sounds—take plenty of liquids and rest. If you’re unfortunate enough to contract scabies (a microscopic mite) or lice, which is possible if you’re staying in unhygienic conditions or sleeping with unhygienic bedfellows, use a body shampoo containing gamma benzene hexachloride. You should also wash all clothing and bedding in very hot water, and toss out your underwear. The severe itching caused by scabies infestation appears after three or four weeks as little dots, often in lines, ending in blisters, especially around the genitals, elbows, wrists, lower abdomen, and nipples. Avoid bees’ nests. Africanized bees have infiltrated Costa Rica, and they’re very aggressive and will attack with little provocation.

Even the slightest scratch can fester quickly in the tropics. Treat cuts promptly and regularly with antiseptic and keep the wound clean.Many bugs are local. The bite of a rare kind of insect found along the southern Caribbean coast and locally called papalamoya produces a deep and horrible infection that can even threaten a limb. It may be best to have such infections treated locally, and certainly promptly; doctors back home or even in San José might take forever to diagnose and treat the condition.

Occasional and serious outbreaks of dengue fever have occurred in recent years, notably around Puntarenas and along the Caribbean coast and the Golfito region. Transmitted by mosquitoes, the illness can be fatal; death usually results from internal hemorrhaging. Its symptoms are similar to malaria, with additional severe pain in the joints and bones (it is sometimes called “breaking bones disease”) but, unlike malaria, the disease is not recurring.

Rabies, though rare, can be contracted through the bite of an infected dog or other animal. It is always fatal unless treated. If you’re sleeping in the open or with an unscreened window open in areas with vampire bats, don’t leave your flesh exposed. Their bite, containing both anesthetic and anticoagulant, is painless.

Intestinal Problems

Water is safe to drink almost everywhere, although more remote rural areas, as well as Escazú, Santa Ana, Puntarenas, and Puerto Limón, are riskier. To play it safe, drink bottled mineral water (agua mineral or soda). Remember, ice cubes are water too, and don’t brush your teeth using suspicious water.

Food hygiene standards in Costa Rica are generally high. However, the change in diet— which may alter the bacteria that are normal and necessary in your gut—may cause temporary diarrhea or constipation. Most cases of diarrhea are caused by microbial gut infections resulting from contaminated food. Common-sense precautions include not eating uncooked fish or shellfish, uncooked vegetables, unwashed salads, or unpeeled fruit. Diarrhea is usually temporary, and many doctors recommend letting it run its course. Personally, I like to plug myself up straightaway with Lomotil (cophenotrope). Treat diarrhea with rest and lots of liquid to replace the water and salts lost. Avoid alcohol and dairy products. If conditions persist, seek medical help.

Diarrhea accompanied by severe abdominal pain, blood in your stool, and fever is a sign of dysentery. Seek immediate medical diagnosis. Tetracycline or ampicillin is normally used to cure bacillary dysentery. More complex professional treatment is required for amoebic dysentery. The symptoms of both are similar. Giardiasis, acquired from infected water, causes diarrhea, bloating, persistent indigestion, and weight loss. Again, seek medical advice. Intestinal worms can be contracted by walking barefoot on infested beaches, grass, or earth.


Malaria is a limited risk in the lowlands, although an increase in the incidence of malaria has been reported in the Caribbean lowlands south of Cahuita; the majority of cases are among banana plantation workers. Consult your physician for the best type of antimalarial medication. Begin taking your tablets a few days (or weeks, depending on the prescription) before arriving in an infected zone, and continue taking the tablets for several weeks after leaving the malarial zone. Malaria symptoms include high fever, shivering, headache, and sometimes diarrhea.

Chloroquine (sold as Alaren in Costa Rica) and Fansidar are both used for short-term protection. Chloroquine reportedly is still good for Costa Rica, although Panamanian mosquitoes have built up a resistance to the drug. Fansidar may be a safer bet for travel south of Puerto Limón. Fansidar can cause severe skin reactions and is dangerous for people with a history of sulfonamide intolerance.

Avon’s Skin-So-Soft oil is such an effective bug repellent that U.S. Marines use it by the truckload (“Gee, private, you sure smell nice, and your skin’s so soft!”). The best mosquito repellents contain DEET (diethylmetatoluamide). Use mosquito netting at night in the lowlands; you can obtain good hammocks and “no-see-um” nets in the U.S. from Campmor (tel. 800/226-7667). A fan over your bed and mosquito coils (espirales) also help keep mosquitoes at bay. Coils are available from pulperías and supermarkets (don’t forget the metal stand—soporte—for them).

Infection, Hepatitis, and HIV/STDs

Even the slightest scratch can fester quickly in the tropics. Treat cuts promptly and regularly with antiseptic and keep the wound clean.

Hepatitis is epidemic throughout Central America, although only infrequently reported in Costa Rica. Main symptoms are stomach pains, loss of appetite, yellowing skin and eyes, and extreme tiredness. Hepatitis A is contracted through unhygienic foods or contaminated water; salads and unpeeled fruits are major culprits. A gamma globulin vaccination is recommended. The much rarer hepatitis B is usually contracted through unclean needles, blood transfusions, or unprotected sex.

The incidence of HIV/AIDS is on the rise throughout Central America. Use of condoms or avoiding casual sexual contact are the best prevention against contracting sexually transmitted diseases.


Snakes are common in Costa Rica. Fewer than 500 snakebites are reported each year, and less than 3 percent of these are fatal. The majority of bites occur from people stepping on snakes. Always watch where you’re walking or putting your hands. Never reach into holes or under rocks, debris, or forest-floor leaf litter without first checking with a stick to see what might be slumbering there. Be particularly wary in long grass. Avoid streams at night. Many snakes are well-camouflaged arboreal creatures that snooze on branches, so never reach for a branch without looking. If you spot a snake, keep a safe distance, and give the highly aggressive fer-delance a very wide berth.

If bitten, seek medical attention without delay. Rural health posts and most national park rangers have antivenin kits on-site. Commercial snakebite kits are normally good only for the specific species for which they were designed, so it will help if you can definitively identify the critter. But don’t endanger yourself further trying to catch it.

If the bite is to a limb, immobilize the limb and apply a tight bandage between the bite and body. Release it for 90 seconds every 15 minutes. Ensure you can slide a finger under the bandage; too tight and you risk further damage. Do not cut the bite area in an attempt to suck out the poison. Recommendations to use electric shock as snakebite treatment have gained popular favor recently in Costa Rica; do not follow this medically discredited advice.

Sunburn and Skin Problems

Don’t underestimate the tropical sun! It is intense and can burn you through light clothing or while you’re lying in the shade. Use a sunscreen or sunblock— at least SPF 15 or higher. Zinc oxide provides almost 100 percent protection. Use an aloe gel after sunbathing. Calamine lotion and aloe gel will soothe light burns; for more serious lobster- pink burns, use steroid creams.

Sun glare—especially prevalent if you’re on water—can cause conjunctivitis (eye infection). Sunglasses will protect against this. Prickly heat is an itchy rash, normally caused by clothing that is too tight or in need of washing. This, and athlete’s foot, are best treated by airing out the body and washing your clothes.

Drink plenty of water to avoid dehydration. Leg cramps, exhaustion, and headaches are possible signs of dehydration.

Excerpted from the Ninth Edition of Moon Costa Rica.