Brugia malayi lives in multiple locations during its life. Although the main habitat recognized for B. malayi is the lymphatic system, the habitat where it is found is generally swampy or tropical. The parasite flourishes in freshwater swamp forests in rural locations in Southeast Asia (Ridley 2011); about 65% of cases are found here. Thirty percent of cases are in the African region, and the rest are usually found in other tropical areas (WHO 2014). Sixty five percent of cases found in Southeast Asia are there because it is mainly rural freshwater swamp forests. Tropical and swamp waters are a very common breeding location for mosquitoes, giving them a higher reproduction rate in these areas. A larger number of infected mosquitoes means more blood meals and more cases of filariasis.                         Above image: Locations where B. malayi is most
                                                                commonly found. Areas where the parasite is
                                                                endemic shown in red.

Brugia malayi is very specialized in its habitat requirements in hosts. In the lymphatic system, the parasite must be transmitted to host by mosquito, then back to mosquito in order to continue infecting hosts. The microfilariae enter the host’s blood during the mosquito’s meal (ADW 2003).  This is why it is always very important to take precautions when visiting tropical regions! Often times, those who are infected are unaware that they were even bitten by a mosquito.

B. malayi is often found in the same locations as another blood-borne disease known as malaria. Malaria is an infection caused by parasitic protozoans in the same regions. Because malaria is also a blood-borne, mosquito transmitted disease, its life cycle is very similar to B. malayi. Malaria causes flu-like symptoms, and if left untreated, can result in death (CDC 2013). While Brugia malayi does not cause death, it can impact quality of life with the physical and mental changes it can make to the host's body.

Left image: Red blood cell infected with malaria.

Hosts of B. malayi include Mansonia, Aedes, Anopheles, and Culex, which are all genera containing different species of mosquitoes used for transmission to definitive hosts. The definitive hosts include Homo sapiens, domestic cats Felis silvestris, monkeys, and forest carnivores (ADW 2003). The hosts that are mosquitoes are used for a home before they are transported to the definitive host - the larger hosts with lymphatic systems. The parasite lives here, in these larger hosts, for most of its life because they feed off of blood and lymph, which is easily acquired in these locations.

Left image:
Left-Wuchereria bancrofti microfilaria. Center- Female Aedes aegypti. Right- Brugia malayi microfilaria

While in their habitat in the lymphatic system, Brugia malayi use their papillae, setae, and aphids for sense. The papillae are used for copulation, setae are for motion detection, and aphids are chemoreceptors used to detect chemicals (ADW 2003). Without these sensory organs, B. malayi would not stay in the body as long as they do (they can live for many years!). They would not be able to reproduce, and the species would go extinct.

The habitat of Brugia malayi is very specialized. They require two hosts and an endosymbiont just to keep reproducing successfully! Without this parasite, millions of people would be living a much happier and healthier life.


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