Mansonella perstans is a filarial (arthropod-borne) nematode (roundworm), transmitted by tiny blood-sucking flies called midges. Mansonella perstans is one of two filarial nematodes that causes serous cavity filariasis in humans. The other filarial nematode is Mansonella ozzardi. M. perstans is widespread in many parts of sub-Saharan Africa, parts of Central and South America, and the Caribbean. Compared to infections with other filarial parasites such as Wuchereria bancrofti, Brugia malayi, and Loa loa, Mansonella infections are relatively mild. However, the pathogenicity of M. perstans infection has been recently reconsidered in various studies. These studies have demonstrated that M. perstans has the ability to induce a variety of clinical features, including angioedema Calabar-like swellings, pruritus, fever, headache, eosinophilia, and abdominal pain. The overall disability among populations in regions where filariae are endemic has been difficult to determine because of high rates of coinfection with other filariae and the nonspecificity of M. perstan infections. Furthermore, treatment of M. perstans is challenging because the most antifilarial drugs, such as ivermectin, diethylcarbamazine, and albendazole are not effective. The optimal treatment for M. perstans infection remains unclear. Most current studies are focused on coinfection of M. perstans with other filarial parasites, and the study of Wolbachia bacteria as endosymbionts in M. perstans and other filarial parasites. History of discovery In 1890, the microfilariae of M. perstans were first discovered by Manson in the blood of a patient from West Africa who was hospitalized with sleeping sickness in London. Because the microfilariae were first noted in a patient with African trypanosomiasis, M. perstans was initially suspected to be the cause of this disease. M. perstans as the cause of African trypanosomyasis was later ruled out by the Royal Society Sleeping Sickness Commission, who showed the geographical distribution of sleeping sickness did not coincide with that of M. perstans infection. Upon their discovery, the microfilariae were named Filaria sanguinis hominis minor, due to their relatively small size when compared to another type of microfilarae found in the same patient (Filaria sanguinis hominis major, which is now known as Loa loa). The name was later changed to Filaria sanguinis hominis perstans, and later again shortened to Filaria perstans to comply with the binary system of nomenclature. Over time, the name continued to change as changes in the generic status of the parasite took place. In 1984, Eberhard and Orihel redefined the genus Mansonella and included the M. perstans species