This is just a small selection of the common and debilitating diseases you commonly encounter overseas ( and in some areas of tropical Australia) which you do not come across in daily life in Australia.

Malaria and dengue fever are mosquito-borne diseases for which there is no vaccine. Your best protection is to prevent yourself from being bitten by mosquitoes.

Scub typhus is also spread by tiny mite in the bush or forest, so the best protection is to prevent yourself from being bitten.

There is a vaccine for rabies, but the best prevention is to avoid animals. The vaccine is advised for people travelling for prolonged periods in rural areas and dealing with animals or bats.

Dengue Fever

Dengue is a viral illness spread by the anopheles mosquito biting in daytime. The symptoms of dengue are high fever, severe headache, backache, joint pains, nausea and vomiting, eye pain, and rash. Generally, younger children have a milder illness than older children and adults.

As no medications or immunisations are available to prevent dengue you must prevent dengue by preventing mosquito bites. Read the section on how to avoid mosquito bites in the section on Malaria.

Malaria

Malaria is spread by the anopheles mosquito which is mainly around and biting between dusk and dawn in rural areas.

It is caused by a protozoan infection which starts in the liver and then spreads to the red blood cells. Malaria causes fever, chills, malaise & headache. Abdominal pain, diarrhoea and jaundice may also occur.

Practical Ways to Avoid Mosquito bites:

Antimalarial drugs do not provide absolute protection so it is very important to avoid mosquito bites by:

• covering up and wearing long sleeves and long trousers;
• avoid using perfumes;
• avoid being outdoor between dusk and dawn, if outside;
• using effective insect repellents which contain DEET;
• using mosquito nets and permethrin-impregnated clothes and;
• permethrin impregnated nets at night when sleeping if staying in rural areas and areas where malaria is highly prevalent.

Some strains of malaria are now resistant to drugs previously used for prevention and treatment.

Malaria occurs throughout most of Asia, the Pacific, Africa, the Middle East, & Central and South America.

Some commonly used Antimalarial Tablets for malaria prevention in adults:

• Chloroquine: Take 2 tablets on the same day once a week with food. Start 2 weeks before entering risk area and continue for 4 weeks after leaving the area. Tell the doctor if you have psoriasis.
• Lariam: Take 1 tablet once a week. Start 1 week before entering a risk area and continue for 4 weeks after leaving the area. Not to be taken with Chloroquine or if scuba diving. It can interact with some cardiac drugs. It occasionally causes dizziness. Don't get pregnant for 3 months after taking it.
• Doxycycline: Take 1 tablet each day with food (not last thing at night). Start 1 day before entering risk area and continue for 2-4 weeks after leaving the area. A small number of people get a rash when exposed to the sun while taking doxycycline, so wear a hat, shirt, and blockout when in the sun. It can interfere with the oral contraceptive pill so use condoms as well for the first 4 weeks.
• Proguanil: Take two tablets each day. Start 1 day before entering risk area and continue until 4 weeks after leaving the area. It is taken with weekly Chloroquine.

Rabies

Rabies is a virus which affects the nervous system. It is spread by a bite or scratch from an infected animal, usually a dog or a monkey (or by inhalation in a bat inhabited cave). It occurs in most of the world but is most common in India, South America, Thailand, the Philippines, and Africa.

Avoid Contact with Animals

Rabies First Aid:

• Flush the wound immediately with soap and lots of water for at least 5 min (20min if possible)
• Irrigate with an iodine antiseptic or alcohol (Scotch if nothing else is available)
• Don't get the wound sutured
• Get medical attention for post-exposure vaccination (an immediate dose of immune globulin and 5 doses of rabies vaccine over 1 month).

Schistomosiasis (Bilharzia)

This is caused by a worm which infects a fresh water snail. The worm penetrates the skin and migrates to the bladder or bowel lining. It occurs throughout Africa (including the Nile valley), the Middle East, China, the Philippines, Sulawesi (Indonesia), the Mekong delta, the Caribbean, and tropical South America.

To prevent becoming infected avoid:

• Swimming or washing in infected water (salt and chlorinated water are safe)
• Only drink treated water
• Avoid going barefoot
• If crossing an infected stream is unavoidable, wear long trousers and shoes and dry out immediately. Try to cross upstream from where people use the river.

Schistosomiasis is treatable so if you may have been exposed, get medical advice on your return home.

Scrub Typhus

Scrub typhus is a rickettsial disease caused by a bacterial infection called Orientia tsutsugamushi.

This germ infects people when they are bitten (usually painlessly) by a very tiny infected larval mite that lives in grassland areas at the edge of dense monsoon forests or forested creeks. They usually feed on native animals. Scrub typhus cannot spread from one person to another.

Scrub typhus is found in Asia, northern Australia and the Pacific region. It extends from south eastern Siberia and northern Japan, through eastern and south-east Asia, to Vanuatu in the east and Pakistan in the west. Its commonest occurrence is in Thailand.

The symptoms usually occur within 1 to 2 weeks of being bitten. They may include fever chills, sweating, headache, cough, swollen glands and a dull red skin rash. The bite may ulcerate and become red with a black scab.

Any person with these symptoms, should mention the possibility of scrub typhus to their doctor. The diagnosis is made by a blood test.

Anyone visiting areas known to have scrub typhus are at risk. Treatment with antibiotics is very effective. Doxycycline is currently the drug of choice. Often people require treatment in hospital.

To prevent scrub typhus you should take precautions from being bitten by mites These include:

• Use footwear such as sneakers or boots with socks rather than walking barefoot or with sandals.
• Apply insect repellent that contains DEET to all exposed skin areas on the legs, on to socks and the base of trousers (this is the same repellent you use to prevent mosquito bites).
• Do not sit or lie on bare ground or grass, use a suitable ground sheet or other ground cover.
• Camp in cleared areas away from dense forests. Use tents with attached floors.
• People who are working in infested areas should consider wearing permethrin (insecticide) impregnated clothing.