MALARIA - SYMPTOMS, TREATMENT AND PREVENTION

Malaria is caused by a parasite called Plasmodium. There are 5 species of Plasmodiumwhich infect humans:

Plasmodium vivax

Plasmodium falciparum

Plasmodium malariae

Plasmodium ovale

Plasmodium knowlesi which is less common.

Of these, Plasmodium falciparum infection is the most severe and can cause death in up to 10% of cases. It can be rapidly fatal. Pregnant women and children are especially at risk. Other types of malaria are less severe, but still may cause death.

Malaria is a notifiable disease.

How malaria is spread

The parasite is transmitted to humans by the bite of infected female Anopheles species mosquitoes.

The parasites multiply in the liver and the bloodstream of the infected person. The parasite may be taken up by another mosquito when it bites an infected person. The mosquito is then infected for the duration of its life and can infect other humans when it bites them.

Occasionally malaria is transmitted by blood transfusion. For this reason, people who have travelled to countries where malaria occurs may be deferred from giving blood for a short period. Malaria can also be transmitted from a mother to her fetus.

Malaria occurs in most tropical and sub-tropical areas of the world, including:

Africa

Central and South America

Asia (including southeast Asia)

Papua New Guinea

western Pacific islands.

Over a million people living in these countries die from malaria each year. Many thousands of tourists also get malaria during their travels to countries where malaria is present. Tourists often get severe illness because they have had no previous exposure to malaria and have no resistance to the disease.

SIGNS AND SYMPTOMS

In humans, the parasites live mostly in the red blood cells, but a very serious complication of Plasmodium falciparum malaria is infection of the brain.

Symptoms of malaria may include:

fever, which may come and go, or may be constant

chills

profuse sweating

malaise (feeling of unwellness)

muscle and joint pain

headache

confusion

nausea

loss of appetite

diarrhoea

abdominal pain

cough.

Diagnosis

Diagnosis is made by a blood test – sometimes it is necessary to repeat the test a number of times, as the parasites can be difficult to detect.

Incubation period

(time between becoming infected and developing symptoms)

Varies with the type:

P. falciparum: 9 to 14 days

P . vivax: 12 to18 days but some strains may have an incubation period of 8 to 10 months or longer

P. ovale: 12 to 18 days

P. malariae: 18 to 40 days.

These periods are approximate and may be longer if the person has been taking drugs taken to prevent infection.

Infectious period

(time during which an infected person can infect others)

Direct person-to-person spread does not occur.

A person remains infectious as long as the parasites are present in the blood. This may be several years if adequate treatment is not given. Parasites disappear from the blood within a few days of commencing appropriate treatment. Mosquitoes remain infected for life.

TREATMENT

Specific antimalarial treatment is available and must always be started as soon as malaria is diagnosed. There is increasing resistance to currently available drugs and treatment should be carried out by an infectious diseases specialist or other expert in the field.

PREVENTION

Exclusion from childcare, preschool, school or work is not necessary but cases should avoid being bitten by mosquitoes while they are unwell

there is no vaccine to prevent human infection by this parasite

personal protection and the environmental management of mosquitoes are important in preventing illness. See Fight the Bite for tips to on how to protect yourself.

Travel in countries where there is malaria?

Extensive international programs are undertaken in malarious countries to try to control this disease. For travellers, the following advice is given:

see a travel medicine expert before you go to get specific advice for the places you will be visiting

always take malaria prophylaxis drugs exactly as prescribed and take the full course. Be aware of their potential side effects

protect yourself from mosquito bites. Travel medical centres have good information on how to do this

be aware that no preventive measures are 100% effective, so always seek medical attention immediately if you develop a fever while travelling in, or after return from, a country where malaria occurs

always give your doctor the information about your travel if you become sick.