Malaria: causes, symptoms and treatment

Malaria is a potentially fatal tropical disease that is caused by a parasite known as Plasmodium.

Malaria causes, symptoms and treatment
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Malaria is a serous tropical disease spread by mosquitoes. There's no risk of catching it in the UK, but if you're lucky enough to be visiting a tropical or subtropical county, it's important to protect yourself from malaria as a single mosquito bite is all it takes to become infected.

Dr Charlie Easmon, a Primary Care Physician specialising in Travel Medicine, explains what malaria is, what the symptoms are and how to treat it:

What is malaria?

Malaria is a potentially fatal tropical disease that's caused by a parasite known as Plasmodium. It's spread through the bite of an infected female mosquito. The infected person may have feverish attacks, influenza-like symptoms, tiredness, diarrhoea or a whole range of other symptoms. Malaria should always be suspected if these symptoms occur within the first year of return from an infected area; a test should be carried out to exclude the possibility of malaria as soon as possible.

Malaria is one of the leading causes of disease and death in the world. It is estimated that there are around 200 million new cases every year, with over 500,000 deaths worldwide (91 per cent in Africa).

Malaria occurs extensively in tropical and subtropical regions. It used to exist in the UK but fortunately no longer does. In recent years, about 1,500 people have returned to Britain with malaria that they have contracted abroad - and, of these, an average of 12 die. For this reason it's important to prevent malaria in those travelling to and from the tropics.



What causes malaria?

The malaria parasite, Plasmodium, is a small, single-cell organism (protozoan), which lives as a parasite in man, monkeys and a specific species of mosquito (Anopheles).

There are four key types of malaria parasite that affect humans: Plasmodium falciparum is the cause of fatal malaria, while Plasmodium vivax, Plasmodium ovale and Plasmodium malariae cause more benign types of malaria. There are several stages in the life cycle of the parasite, and by and large these are the same for all four types.



How do you catch malaria?

Malaria is caused on by the female Anopheles mosquito biting a person who has malaria parasites in their blood then passing these on when she takes her next feed on another person. The parasites develop in the intestine and salivary glands of the mosquito and can be passed on to other people the next time the mosquito bites.

In man, the parasite travels to the liver via the blood and then out into the bloodstream again, where it invades the red blood corpuscles (the cells which carry oxygen in the blood). Malaria can also be passed on by blood transfusions and the use of infected needles.



Where does malaria occur?

Malaria occurs where the Anopheles mosquito lives - ie particularly in hot, humid climates. Plasmodium falciparum is by far the most important malaria parasite in Africa.

There are also areas in: Latin America, Asia, and Oceania, where fatal malaria still occurs. Plasmodium vivax is the most common in Asia and Latin America, including Central America. Always check the National Travel Health Network and Centre for up-to-date advice.



What are the symptoms of malaria?

The attack may be what is called uncomplicated or severe. Classic symptoms would be:

• Fever and shivering. The attack begins with fever, with the temperature rising as high as 40ºC and falling again over a period of several hours

• Poor general condition, feeling unwell and having headaches like influenza

Diarrhoea, nausea and vomiting often occur as well.

While malaria can seem just like a mild flu, tiredness may be the only initial symptom or to make diagnosis even more difficult just simple diarrhoea. If a case shifts to severe malaria, the classic symptoms above would be expected with increased drowsiness, leading to coma and associated failure of all the major organ systems.



What's the outlook for those with malaria?

When the temperature drops, the patient often sweats profusely and feels much better. Then the same day, or one to two days later, further attacks occur with feeling generally unwell, high temperature and so on.

The attacks diminish in the course of a number of weeks, if the patient develops the ability to resist the malaria parasite. But if proper treatment is given, the fever and parasites can disappear within a few days.

If proper treatment is given, the fever and parasites can disappear within a few days.

No-one is ever completely immune to malaria, but the concept of semi or partial immunity exists, in which attacks are less severe and less likely to kill. But the price for this is multiple exposures (which kill many children).

Many people from Africa and India assume they have full or partial immunity to malaria, and these people who visit friends and relatives abroad (VFRs) compromise the largest numbers of imported malaria cases in the UK. In severe malaria the illness may evolve with a number of complications:

  • Low blood pressure (hypotension).
  • Kidney failure.
  • Possible haemorrhage (bleeding).
  • Effects on the liver (eg infectious jaundice).
  • Shock and coma may also develop, and the condition may prove fatal.


    What can you do yourself?

    Because the situation can change rapidly: you should talk to a doctor, travel clinic or pharmacist before planning your trip, both as regards to products for malaria prevention and also for expert advice on avoiding other dangers and diseases.

    Prevention of malaria is important. If you travel to a region where malaria is prevalent, you should take preventive medication against the parasite and take whatever steps you can to avoid being bitten.



    How is malaria diagnosed?

    The symptoms of malaria are similar to those of many other diseases and infections that can cause fever or upset the stomach. Therefore you should always tell your doctor if you have been abroad, especially if you've been to the tropics in the last 12 months.

    You should always tell your doctor if you have been abroad, especially if you've been to the tropics

    The gold standard actual diagnosis is made by detecting the parasite in the blood. This is done using a special product mixed with one to two drops of the patient's blood and spreading it on a microscope slide. This is then stained and examined carefully under a microscope.

    But many laboratories in the UK and overseas now use rapid antibody based screening tests. These can give results in 15 minutes.The examination may have to be repeated if the fever has only just begun or preventive medication is to some extent keeping the numbers of the malaria parasite low.



    Malaria treatment

    The treatment of malaria normally calls for admission to hospital because it may be falciparum malaria that can have a fatal outcome in only a few days or hours. Outpatient treatment or, worse still, self-treatment of malaria is something only to be undertaken when no qualified medical help is available, ie if you develop malaria in a remote area.

    The same antimalarial agents may be used to treat malaria as to prevent it. But if you have caught malaria in spite of using the correct preventive medication, a different product should be used to combat the possibility of resistant parasites. There are promising results from two separate malaria vaccine trials but it may be several years before these are commercially available.



    Dr Charlie Easmon is a Primary Care Physician specialising in Travel Medicine, Mental and Occupational Health.Dr Easmon achieved his Diploma in Tropical Medicine and Hygiene at LSTM in 1995, after training as St George’s Hospital Medical School and performing his medical elective in Ghana.
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