Last updated:
9/25/2025
Years published: 1986, 1993, 1997, 2005, 2009, 2025
NORD gratefully acknowledges Gioconda Alyea, MD (FMG), MS, National Organization for Rare Disorders for the preparation of this report.
Mansonellosis due to Mansonella perstan (M.perstans), also known as acanthocheilonemiasis or dipetalonemiasis, is a rare tropical infectious disease caused by a parasite known as Mansonella perstan (also known as Acanthocheilonema perstans or Dipetalonema perstans).1,2
Although many people with this infection remain asymptomatic, symptoms can include red, itchy skin (pruritus), abdominal and chest pain, muscular pain (myalgia) and areas of localized swelling (edema). In addition, the liver and spleen may become abnormally enlarged (hepatosplenomegaly). Laboratory testing may also reveal abnormally elevated levels of certain specialized white blood cells (eosinophilia). The parasite is transmitted through the bite of small flies of the Culicoides genre (biting midges).2
Mansonellosis due to M. perstan belongs to a group of parasitic diseases known as filarial diseases or “filariasis”, that are caused by nematodos.1,2 This parasite is mainly found in Africa. A large part of the world’s population is infected with one or more filarial parasites.2,3
Three types of Mansonella can infect humans: M. ozzardi, M. perstans (and M. streptocerca also called Dipetalonema streptocerca).
Even though Mansonellosis is the most prevalent among the human filariases, affecting hundreds of millions of people in Africa and Central and South America, it remains one of the least studied and most neglected of all filarial diseases.3
There are no official treatment guidelines for Mansonellosis.2,3
Initially people with Mansonellosis caused by Mansonella perstans may have no symptoms. Symptoms occur more frequently in people who visit the areas where this parasite is common (endemic) than in people who are native to that area. One common laboratory finding in people who have recently returned from infected areas is abnormally elevated levels of eosinophils in the blood (eosinophilia), a type of white blood cell that is usually increased in parasitic infections and allergies.1,2
When symptoms appear, they may include:1,2,3,,4,5
The adult worm (nematode) may lodge in the tissues of the abdomen and chest causing inflammation and immune reactions. This may result in inflammation of the lining of the lungs (pleuritis) and/or the membranes that surround the heart (pericarditis).1,2,3
Mansonellosis caused by Mansonella perstans is a parasitic infectious disease caused by long “thread-like” tiny worms known as Mansonella perstans. The infection is spread through the bite of small insects. In Africa, the main carriers are midges from the Culicoides family.2,3,7,8 When an infected insect bites a person, it injects larvae that grow into adult worms inside the body. These adult worms settle in body cavities or under the skin and release thousands of microscopic larvae called microfilariae into the bloodstream. When another insect bites the infected person, it ingests these microfilariae, continuing the cycle of infection.3
Mansonella perstans is common in central Africa and in some areas of South America. It has been estimated that 114 million people may be infected and about 600 million people in 33 countries are at risk for M. perstans infection in Africa alone. While extremely rare, it has been reported in the USA, linked to travel to endemic areas. This disorder affects males and females in equal numbers.2,3,5,7,9 Despite mass drug campaigns using ivermectin to combat other parasitic diseases, Mansonella infections, particularly infections caused by Mansonella perstans, persist in many regions, suggesting ivermectin has limited effect on this parasite.2,3,7,8
Diagnosis of Mansonellosis caused by Mansonella perstans usually involves examining a blood sample under a microscope to detect microfilariae. However, since these worms do not always show up clearly or consistently in the blood, newer testing methods are sometimes used. These include blood tests that check for signs of the parasite like antigens (proteins from the parasite) or antibodies (the body’s immune response to the parasite). Another method is PCR (polymerase chain reaction), a laboratory technique that can detect even small amounts of the parasite’s DNA for a more accurate diagnosis.1,2,3, 6, 7,8
There is no official treatment for Mansonellosis caused by Mansonella perstans or for any of the other diseases caused by other types of Mansonella (Mansonellosis) in general. It is treated by means of the administration of antifilarial drugs, some of which are newer than others. Nonetheless, medications like diethylcarbamazine and mebendazole have been used to reduce the parasite load, although their effectiveness at fully clearing the infection is uncertain.2,3,11
A more promising option is doxycycline, an antibiotic that targets Wolbachia, a bacterium that many Mansonella worms carry inside and rely on to survive. Research in West Africa has shown that most M. perstans parasites carry Wolbachia, and people treated with doxycycline experienced a drop in microfilariae levels, suggesting that this could be an effective first-line treatment, especially when follow-up testing is possible.2,3,11
In regions where Wolbachia presence is unknown, testing before starting doxycycline may help guide the most appropriate treatment plan. While ivermectin is commonly used in mass drug programs for other parasitic diseases, it has shown limited success against Mansonella, especially in areas where the infection remains widespread despite ongoing treatment efforts.2,3,8,11,12,13,14
Occasionally, surgery may be required to remove large adult worms. Mild cases of Mansonellosis iasis do not require treatment.2
Information on current clinical trials is posted on the Internet at https://clinicaltrials.gov/. All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Toll-free: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
Some current clinical trials also are posted on the following page on the NORD website:
https://rarediseases.org/living-with-a-rare-disease/find-clinical-trials/
For information about clinical trials sponsored by private sources, contact:
https://www.centerwatch.com/
For information about clinical trials conducted in Europe, contact:
https://www.clinicaltrialsregister.eu/
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