Malaria remains the world number one infectious disease. The incidence of malaria is on the rise with half the world’s population at risk. In 2008, there were an estimated 247 million cases and nearly one million deaths.
It is widespread in tropical and subtropical areas i.e. hot and humid climates. Malaria is most prevalent in Africa, South America and Asia.
Malaria is an infection characterised by fever, shivering, chills, malaise, headache and sweats, but it can present as a respiratory or gastrointestinal illness. It is caused by any of four different species of the Plasmodium parasite, passed on via the bite of an infected mosquito. Malaria caused by Plasmodium falciparum is life threatening.
Mode of transmission and incubation period
Parasites are transmitted from one person to another by the female anopheline mosquito. The parasites develop in the gut of the mosquito & are passed on in the saliva of an infective mosquito each time it takes a new blood meal. The parasites are then carried by the blood in the victim's liver where they invade the cells & multiply.
After 9-16 days they return to the blood & penetrate the red cells, where they multiply again, progressively breaking down the red cells. This induces bouts of fever & anaemia in the infected individual. In cerebral malaria, the infected red cells obstruct the blood vessels in the brain. Other vital organs can also be damaged often leading to the death of the patient.
- A slow rising fever that escalates to a rapid temperature rise and fall
- Excessive sweating
- General malaise
- Anaemia and associated symptoms
Four different species of parasite
There are four different types of malaria parasite: Plasmodium falciparum is the cause of fatal malaria, while Plasmodium vivax, Plasmodium ovale and Plasmodium malariae cause more benign types of malaria. Falciparum malaria can kill, but the other forms are much less likely to prove fatal.
The typical symptoms of malaria described above can lead to further symptoms and complications in the case of P. falciparum infection, including:
- Coagulation defects (blood doesn't clot)
- Rupture of the spleen
- Haemolytic anaemia (the red cells don't live a normal life span)
- Kidney failure
- Liver failure
- Pulmonary oedema
- Cerebral malaria, producing coma
Early diagnosis and treatment of malaria reduces disease and prevents deaths. Furthermore, it helps reduce the transmission of malaria.
The best available treatment, particularly for P. falciparum malaria, is artemisinin-based combination therapy (ACT).
If you are visiting a malaria zone see your Travel Health advisor at least a month prior to travelling so that suitable medication can be arranged to help prevent malaria. Malaria can be prevented through chemoprophylaxis, which suppresses the blood stage of malaria infections, thereby preventing malaria disease. Most medication is taken for a set period before going, continued while you are in a malaria zone and for a set period on return.
The three main anti-malarial drugs are Malarone, Doxycycline and Lariam.
The most appropriate drug for use is based on the country of travel and individual conditions including any heart conditions, pregnancy, breast feeding or epilepsy. It is important that you inform your travel health advisor as this might influence the medication you are given.
Mosquitoes feed between dusk and dawn. The mosquitoes tend to respond to light in their feeding habits and are most active in low light hours after dusk and in the hours prior to dawn. Female mosquitoes will take a blood meal just before laying their eggs, which are laid at night. It is therefore important that repellents are used between dusk and dawn to prevent being bitten.
Use a Repellent that has DEET, or contains a natural repellent such as lemon and eucalyptus; try to avoid using products that are connected to homemade concoctions!
While clothing alone will not protect you against mosquito bites, it can help in preventing bites when used along with other careful prevention. Clothing that covers the body, such as long trousers and long sleeves; socks etc, worn after dark will lower the risk of being bitten. While mosquitoes are able to bite through many materials, canvas mosquito boots and thick denim jeans will make it more difficult.
Clothing that has been impregnated with permethrin will also help repel mosquitoes. This clothing along with impregnated wrist and ankle bands lower the risk of being bitten. If you are reluctant to impregnate everyday clothing, impregnated netting worn over the clothing will prevent chemical contact with the skin. It is important that fellow travellers are protected in a similar way, as repelled mosquitoes will go to another person who is not protected!
Research has suggested that mosquitoes are attracted to sweat and so keeping clothes clean, especially socks (!) might help. It has also been suggested that mosquitoes are attracted to dark colours, so wearing light colours or white clothing might help prevent being bitten.
While air conditioning does help keep the mosquitoes away due to the lower temperature, it is important that it is left on all day and that the windows are not left open at night! Spray the room with a residual insecticide before entering to kill any mosquitoes that may have entered the room during the day.
Using a mosquito net in an area where malaria is present is a good idea. Ideally the net should be impregnated with permethrin at least every six months or when it is washed.
Use a mosquito repellent cream or spray containing diethyl toluamide (DEET) that effectively helps to repel mosquitoes and insects. It is safe to use in adults, elderly and children.