There are a variety of medications available. The effectiveness of the Chloroquine and Paludrine combination is now limited in most of Southeast Asia. Common side effects include nausea (40% of people) and mouth ulcers. It is generally not recommended.

Lariam (Mefloquine) has received much bad press, some of it justified, some not. This weekly tablet suits many people. Serious side effects are rare but include depression, anxi­ety, psychosis and seizures. Anyone with a history of depression, anxiety, other psycho­logical disorder, or epilepsy should not take Lariam. It is considered safe in the second and third trimesters of pregnancy. It is around 90% effective in most parts of Southeast Asia, but there is significant resistance in parts of northern Thailand, Laos and Cambodia. Tab­lets must be taken for four weeks after leaving the risk area.

Doxycycline, taken as a daily tablet, is a broad-spectrum antibiotic that has the added benefit of helping to prevent a variety of tropical diseases, including leptospirosis, tick-borne disease, typhus and melioidosis. The potential side effects include photosen-sitiviry (a tendency to sunburn), thrush in women, indigestion, heartburn, nausea and interference with the contraceptive pill. More serious side effects include ulceration of the oesophagus - you can help prevent this by taking your tablet with a meal and a large glass of water, and never lying down within half an hour of taking it. It must be taken for four weeks after leaving the risk area.

Malarone is a new drug combining Atovaquone and Proguanil. Side effects are uncommon and mild, most commonly nausea and headaches. It is the best tablet for scuba divers and for those on short trips to high-risk areas. It must be taken for one week after leaving the risk area.

Derivatives of Artesunate are not suitable as a preventive medication. They are useful treatments under medical supervision.

A final option is to take no preventive med­ication but to have a supply of emergency medication should you develop the symptoms of malaria. This is less than ideal, and you'll need to get to a good medical facility within 24 hours of developing a fever. If you choose this option the most effective and safest treatment is Malarone (four tablets once daily for three days). Other options include Mefloquine and Quinine but the side effects of these drugs at treatment doses make them less desirable. Fansidar is no longer recommended.

Measles

Measles remains a problem in some parts of Southeast Asia. This highly contagious bac­terial infection is spread via coughing and sneezing. Most people born before 1966 are immune as they had the disease in childhood. Measles starts with a high fever and rash and can be complicated by pneumonia and brain disease. There is no specific treatment.

Melioidosis

This infection is contracted by skin contact with soil. It is rare in travellers. The symp­toms are very similar to those experienced by tuberculosis sufferers. There is no vaccine but it can be treated with medication.

Opisthorchiasis (Liver Flukes)

These are tiny worms that are occasionally present in freshwater fish in Laos. The main risk comes from eating raw or undercooked fish. Travellers should in particular avoid eating uncookedpqa daek (an unpasteurised fermented fish used as an accompaniment for many Lao foods) when travelling in rural Laos. The f if a daek in Vientiane and Luang Prabang is said to be safe (or safer) simply because it is usually produced from noninfected fish, while the risk of infestation is greatest in the southern provinces.

A rarer way to contract liver flukes is by swimming in the Mekong River or its tributar­ies around Don Khong (Khong Island) in the far south of Laos.

At low levels, there are virtually no symp­toms at all; at higher levels, an overall fatigue, a low-grade fever and swollen or tender liver (or general abdominal pain) are the usual symptoms, along with worms or worm eggs in the faeces. Opisthorchiasis is easily treated with medication. Untreated, patients may develop serious liver infections several years after contact.

Rabies

This uniformly fatal disease is spread by the bite or lick of an infected animal - most com­monly a dog or monkey. You should seek medical advice immediately after any animal bite and commence post-exposure treat­ment. Having a pretravel vaccination means the postbite treatment is greatly simplified. If an animal bites you, gently wash the wound with soap and water, and apply iodine based antiseptic. If you are not vaccinated you will need to receive rabies immunoglobulin as soon as possible.

Schistosomiasis

Schistosomiasis (also called bilharzia) is a tiny parasite that enters your skin when swimming in contaminated water - travellers usually only get a light, symptomless infection. If you are concerned, you can be tested three months after exposure. On rare occasions, travellers may develop 'Katayama fever'. It can occur some weeks after exposure, as the parasite passes through the lungs and causes an allergic reaction - symptoms are coughing and fever. Schistosomiasis is easily treated with medications.

STDs

Sexually transmitted diseases most com­mon in Laos include herpes, warts, syphilis, gonorrhea and Chlamydia. People carrying these diseases often have no signs of infec­tion. Condoms will prevent gonorrhoea and chlamydia but not warts or herpes. If after a sexual encounter you develop any rash lumps, discharge or pains when passing urine seek immediate medical attention. If you have been sexually active during your travels have an STD check on your return home.

Strongyloides

This parasite, also transmitted by skin con­tact with soil, rarely affects travellers. It is characterised by an unusual skin rash called larva currens - a linear rash on the trunk which comes and goes. Most people don't have other symptoms until their immune sys­tem becomes severely suppressed, when the parasite can cause an overwhelming infection. It can be treated with medication.

Tuberculosis

Tuberculosis (TB) is very rare in short-term travellers. Medical and aid workers, and long-term travellers who have significant contact with the local population should take precau­tions, however. Vaccination is usually only given to children under the age of five, but adults at risk are recommended pre- and post-travel TB testing. The main symptoms are fever, cough, weight loss, night sweats and tiredness.

Typhoid

This serious bacterial infection is also spread via food and water. It gives a high, slowly progressive fever and headache, and may be accompanied by a dry cough and stomach pain. It is diagnosed by blood tests and treated with antibiotics. Vaccination is recommended for all travellers spending more than a week in Southeast Asia, or travelling outside of the major cities. Be aware that vaccination is not 100% effective so you must still be careful with what you eat and drink.

Typhus

Murine typhus is spread by the bite of a flea whereas scrub typhus is spread via a mite. These diseases are rare in travellers. Symp­toms include fever, muscle pains and a rash. You can avoid these diseases by following general insect-avoidance measures. Doxycy-cline will also prevent them.