Infectious diseases transmitted by other mosquitoes

Malaria

Malaria is an infectious disease that affects a wide range of animals (reptiles, birds, mammals) and is caused by the Plasmodium parasite. Five different species of malaria parasite are responsible for human infections (Plasmodium falciparum, P. vivax, P. malariae, P. ovale and P. knowlesi). These species are found in all (sub)tropical regions of the world. These parasites cause many cases of malaria and deaths throughout the world, particularly in children under the age of 5 in Africa. 

The malaria parasite is transmitted by certain mosquitoes of the genus Anopheles. Malaria has not been Endemic Persistent circulation of a disease or Pathogen Micro-organism capable of causing disease. in a population or geographical area. in Europe since the 1970s, thanks to medical treatment and the fight against breeding sites and mosquitoes. However, due to the presence in Europe of mosquito species that can act as vectors, there are still occasional local epidemics, as in Greece (in 2011-2012). In Europe, however, malaria is still mainly an imported disease, i.e. contracted by travellers while abroad. 

As well as being transmitted by mosquitoes, malaria can also be transmitted through blood transfusions, during pregnancy and through the re-use of contaminated needles.

What are the symptoms and complications?

After an Incubation period Time between infection and appearance of symptoms. of 10 to 14 days on average, symptoms such as fever with chills, headaches and muscle pains appear. Depending on the type of Plasmodium, fever peaks may occur every 48 hours (malaria tertiana or third-day fever, with P. vivax or P. ovale) or every 72 hours (malaria quartana or fourth-day fever, with P. malariae). The form caused by P. falciparum, also known as malaria tropica, causes irregular fever and is the most severe, even fatal. Young children, pregnant women and people with HIV/AIDS are more likely to develop a severe form.

The parasites of P. vivax and P. ovale can remain dormant in the body and reactivate months or years after infection, causing symptoms once again. People who live in malaria-infected areas and are regularly exposed to malaria can develop a form of immunity that reduces or eliminates symptoms in the event of infection. This protection disappears when exposure ceases over a period of time.

How is malaria diagnosed?

Anyone who develops a fever within a few months of returning from a malaria zone should consider the possibility of malaria. Even if the trip took place several months ago, it is best to talk to the doctor. If the doctor suspects malaria, the diagnosis can be made by taking a blood sample. Depending on the stage of the disease, different tests may be used, such as microscopic examination, PCR Acronym for polymerase chain reaction, is a technique used in laboratories to amplify DNA fragments. This technique is used for rapid diagnosis of the presence of pathogens, for example. or an Antigenic test Test used to detect antigens (foreign substance, for example present on a pathogen, which stimulates an immune reaction (i.e. the production of antibodies)).

How is the disease treated and prevented?

Rapid diagnosis means that the right treatment can be given, depending on the type of Plasmodium. 

There are also drugs that can be taken as a preventive measure when travelling to malaria zones, to prevent severe forms of malaria (chemoprophylaxis). Prevention also involves avoiding mosquito bites.

A vaccine has recently been developed and is recommended by the World Health Organisation (WHO) for children living in regions where P. falciparum malaria is prevalent, such as sub-Saharan Africa. This vaccine is not available for travellers.