When a mosquito carrying a malaria causing parasite bites another infected host, more than one type of parasite exists in the animal’s body. This is called co-infection. There has been very little research into this phenomenon to see whether the transmitted parasites are more harmful in terms of the disease produced.
Malaria is caused by a single celled parasitic animal of the species Plasmodium. The parasite is transferred between hosts by the mosquito (commonly of the family Anopheles.) Mosquitoes spread the parasite to humans through their bites; the parasite then travels to the liver, where it matures and reproduces in forms that infect the red cells and cause clinical symptoms.
Scientists working at University of Edinburgh have studied mosquitoes infected with different Plasmodium strains to see what types of interactions occur. To test this out they used mosquitoes infected with two different parasitic strains and allowed them, at set times, to feed on mice.
According to the research note it was “found that mosquitoes can accumulate mixed strain malaria infections after feeding on multiple hosts, and found that parasites have a greater chance of establishing a secondary infection if another Plasmodium strain is already present in a mosquito.”
Here it was discovered that while the dominant parasite causes the main form of malaria, the less dominant parasite also triggers a different form of malaria, arising as a secondary infection.
Given that different types of parasites require different anti-malaria medications and that drug resistance is growing problem, this means that such infections are much harder to treat. The information, while presenting problems, allows a new medical approach to be considered.
The research has been published in the journal PLOS Pathogens. The study is titled “Existing Infection Facilitates Establishment and Density of Malaria Parasites in Their Mosquito Vector.”
