What Causes Malaria?

What causes malaria

Do you know how malaria is spread?

Malaria is a mosquito-borne disease that kills hundreds of thousands of people every single year. Particularly prevalent in sub-Saharan Africa, it is also widespread in areas of South and South East Asia, Central and South America, the Middle East, and the Pacific Islands. As the disease is prevalent in many popular travel destinations, travellers must take steps to avoid getting bitten and, in some cases, take antimalarial tablets to stay properly protected.

If you are travelling to a malaria zone, read on to find out about the causes of malaria, and how you can avoid contracting the disease.

The causes of malaria

The first thing to know is that malaria is caused by a type of parasite known as Plasmodium. There are five different types of the Plasmodium parasite that cause malaria in humans:

  • Plasmodium falciparum
  • Plasmodium vivax
  • Plasmodium ovale
  • Plasmodium malariae
  • Plasmodium knowlesi

These parasites are spread to humans via female Anopheles mosquitoes, which tend to feed between dusk and dawn. When a mosquito bites a person infected with malaria they take on malaria parasites, which pass to the insect’s salivary glands.

The next time the mosquito bites someone, those parasites enter the person’s bloodstream, where they travel to the liver and incubate for a period of days or weeks. After this incubation period, the parasites then enter the bloodstream, at which point symptoms begin, sometimes occurring in cycles of two or three days.

Unlike other tropical diseases, malaria is not contagious and cannot be passed on from person to person directly. It is nearly always transmitted via the bite of a mosquito. In extremely rare cases, it is possible to contract malaria from blood transfusions or sharing needles.

Plasmodium falciparum

This type of Plasmodium parasite is the most common and deadly. It is responsible for the majority of malaria deaths, and is most prevalent in sub-Saharan Africa. In 2016, 1,308 diagnoses of malaria caused by P. falciparum were reported in the UK, accounting for over 80% of all malaria cases.

Malaria caused by P. falciparum often leads to severe symptoms such as anaemia, as this type of parasite multiples rapidly in the blood. Falciparum malaria requires swift treatment, preferably within 24 hours of the onset of symptoms.

Plasmodium vivax

This malaria parasite is not common in Africa; it is most often found in Asia, and Central and South America. In 2016, Plasmodium vivax caused 166 cases of malaria in the UK (just over 10% of all cases).

One of the key problems associated with the P. vivax parasite is that it can remain in the liver for up to three years, causing relapses of symptoms.

Plasmodium ovale

The P. ovale parasite is similar to the P. vivax parasite in that both can remain in the liver for several months or years, causing future bouts of symptoms. Unlike P. vivax, this parasite is found in Africa, and particularly West Africa. In 2016, it was responsible for just over 5% of malaria cases in the UK.

Plasmodium malariae

This type of malaria parasite is fairly rare, but has been found in a number of different countries. P. malariae is distinctive from other malaria parasites as it typically has a longer incubation period (i.e. symptoms take longer to develop). Bouts of symptoms are sometimes seen to occur every three days, whereas most other types of malaria parasite cause symptoms every two days.

Left untreated, P. malariae can lead to chronic infection and kidney damage. In 2016, 2.5% of malaria cases in the UK were caused by this parasite.

Plasmodium knowlesi

The rarest malaria parasite is P. knowlesi (there was only one malaria case caused by this parasite in the UK in 2016). Though it is rare, it is one of the more dangerous malaria parasites, as it can progress very quickly and cause severe symptoms.

Preventing malaria

Because malaria is spread by mosquitoes, the best way to protect yourself from the disease is to practise bite avoidance. While in an area affected by malaria you should:

  • Use mosquito repellent on exposed areas of skin
  • Cover your arms and legs with clothing
  • Use plug-in insecticides in your accommodation
  • Book accommodation with air conditioning and mosquito screens on the doors and windows
  • When sleeping in more basic accommodation, use a mosquito net impregnated with insecticide
  • Be particularly cautious between dusk and dawn when Anopheles mosquitoes are active

In addition to bite avoidance, you may also need to take antimalarials when you travel to certain parts of the world. Each type of antimalarial tablet provides a different kind of protection for different areas of the world. The antimalarial medicine chloroquine, for instance, no longer offers effective protection against Plasmodium falciparum which is why it is not recommended for travel to Africa.

You should always consult a medical professional before you try to get hold of malaria tablets. You can make an appointment with your GP, book a consultation with MASTA, or visit the LloydsPharmacy Online Doctor Malaria Clinic for an online consultation.

Sources:

www.gov.uk/government/uploads/system/uploads/attachment_data/Guidelines_for_malaria_prevention_in_travellers_from_the_UK_2017.pdf

www.who.int/mediacentre/factsheets/fs094/en/

www.cdc.gov/malaria/about/biology/parasites.html

www.nhs.uk/conditions/malaria/causes/

www.cdc.gov/malaria/about/disease.html