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Mansonella Perstans Infection

Last updated Nov. 13, 2018

Approved by: Krish Tangella MD, MBA, FCAP

Mansonelliasis (or mansonellosis) is the condition of infection by the nematode Mansonella. The disease exists in Africa and tropical Americas, spread by biting midges or blackflies. It is usually asymptomatic.

What are other Names for this Condition? (Also known as/Synonyms)

  • Bulge-Eye Disease
  • Mansonelliasis
  • Serous Cavity Filariasis caused by Mansonella Perstans

What is Mansonella Perstans Infection? (Definition/Background Information)

  • Mansonella Perstans Infection describes an infection of the serous cavities of the body by a worm known as Mansonella perstans
  • The worms may inhabit the serous cavities of humans and other apes such as gorillas and chimpanzees. Serous cavities are body cavities that include the pleural, pericardial, and peritoneal cavities
  • Mansonella perstans (or M. perstans) worms are part of a larger group of worms known as filarial worms. Filarial worms cause a broader classification of disease known as filariasis
  • Adult M. perstans produce tiny larval worms known as microfilariae
    • Culicoides are a genus of blood-sucking midge (a type of small winged insect) that take up the microfilariae while feeding on an infected individual
    • The microfilariae then mature to a later larval stage within the midge, and are transmitted to an uninfected individual following another bite
  • Mansonella Perstans Infection is commonly found in regions of Central Africa, Central America, and South America and any individual at these locations may be prone to infection
  • The symptoms caused by M. perstans infections are mostly mild, and many individuals are asymptomatic. Some individuals may develop red and itchy swellings on the skin
  • Infections caused by M. perstans are commonly treated using drugs that are effective against filarial worms. Clinical studies have shown that a combination therapy of such drugs produces the best results. The prognosis of the Mansonella Perstans Infection is generally good; since in many cases, the infection is mild
  • The small size of the midges makes mosquito nets relatively ineffective in preventing Mansonella Perstans Infection. The best methods of prevention involve eliminating populations of Culicoides and applying insect repellents

Who gets Mansonella Perstans Infection? (Age and Sex Distribution)

  • Mansonella Perstans Infection is acquired when in individual is bitten by a Culicoides midge (insect) harboring the parasite M. perstans. Individuals that are bitten show no age, gender, race, or ethnic bias
  • Individuals living in areas endemic to M. perstans are at the highest risk for developing infection
    • These areas include Central Africa, Central America, and South America
    • The incidence of infection is noted to be over 90% in countries such as Trinidad, Guyana, and Columbia

What are the Risk Factors for Mansonella Perstans Infection? (Predisposing Factors)

The major risk factors for Mansonella Perstans Infection include:

  • Living in areas endemic to the condition, or traveling to the same areas
  • Heavy exposure to infected individuals and infected Culicoides midges
  • Having a weakened immune system

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one's chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Mansonella Perstans Infection? (Etiology)

Mansonella Perstans Infection is caused by the filarial nematode (worm) Mansonella perstans.

  • Culicoides midges become infected with microfilarial (larval) M. perstans upon biting an infected individual. These microfilariae develop in the midge and are passed onto an uninfected individual through another bite
  • Only individuals living in areas endemic to Mansonella perstans are seen to develop the infection

What are the Signs and Symptoms of Mansonella Perstans Infection?

Mansonella Perstans Infection is a rather mild infection in comparison to similar types of filarial worm infections. Many individuals do not have any signs and symptoms, but those that do, typically present with the following:

  • Itchiness
  • Red, itchy swellings on the arms or underneath the eye
  • Hives
  • Headaches
  • Fever
  • Pain in the abdomen
  • Neurologic abnormalities

How is Mansonella Perstans Infection Diagnosed?

A diagnosis of Mansonella Perstans Infection is made by a qualified healthcare professional.

  • A full physical examination is undertaken including a complete medical history evaluation
  • A history of residence or travel in the endemic areas where infection from M. perstans is common, would be a significant factor in determining a diagnosis of Mansonella Perstans Infection
  • The following methods may be used in the diagnosis:
    • A blood sample may be examined under the microscope for the presence of M. perstans microfilariae
    • Serosal effusion (fluid) from the serous cavities of the body may also be examined for M. perstans. This may include pleural fluid, ascitic fluid etc.
    • Tests may be done to determine if antibodies produced as a consequence of M. perstans are present in blood

Many clinical conditions can have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the Possible Complications of Mansonella Perstans Infection?

Mansonella Perstans Infection is generally quite mild and does not cause any significant complications.

How is Mansonella Perstans Infection Treated?

A healthcare professional will determine the best method to treat Mansonella Perstans Infection.

  • Infections of M. perstans that are asymptomatic will generally be left untreated; most individuals may not be even aware that they harbor an infection
  • Drugs that are normally used to treat other filarial infections demonstrate limited use against M. Perstans Infection

When drug therapy is effective, a combination of drugs is seen to produce the best result. A combination of the following drugs may be used to treat the infection:

  • Diethylcarbamazine (DEC):
    • DEC is the most common drug used to treat filarial infections. However, in treatment of Mansonella Perstans Infection, clinical trials have shown DEC to be relatively ineffective, when used on its own
    • At least two doses of DEC are needed to reduce the numbers of M. perstans and alleviate the symptoms associated with the infection
  • Mebendazole: Mebendazole is slightly more effective than DEC in eliminating infections caused by M. perstans
  • Combination of DEC and mebendazole: A combination of the aforementioned drugs has proven to be effective in clinical trials towards reducing the amounts of circulating M. perstans microfilariae and adult M. perstans
  • A follow-up appointment should be made with a healthcare professional following a treatment regimen of diethylcarbamazine and mebendazole

How can Mansonella Perstans Infection be Prevented?

The best way to prevent Mansonella Perstans Infection is through the use of an insect repellent.

  • Mosquito nets are mostly ineffective because the midges that transmit the M. perstans are small enough to fly through the net/mesh
  • Eliminating the swamp-like areas where Culicoides midges breed is proven to be more effective in prevention
  • Avoiding travel to the endemic areas can also help eliminate the risk of contracting the infection

What is the Prognosis for Mansonella Perstans Infection? (Outcomes/Resolutions)

  • The prognosis for Mansonella Perstans Infection is generally very good. In fact, among filarial infections, infections due to M. perstans are considered to be among the mildest
  • Early diagnosis and appropriate treatment of the infection can help improve the prognosis
  • Often times, individuals are asymptomatic and may even be unaware that they have been infected
  • Even for individuals with symptomatic infections, M. perstans infections do not progress past mild fever, headache, and occasional rashes or swellings. As such, the prognosis remains good

Additional and Relevant Useful Information for Mansonella Perstans Infection:

  • Some clinical studies have suggested that treatments targeting the bacteria Wolbachia may be effective in treating Mansonella Perstans Infection
  • Wolbachia live within M. perstans microfilariae, and the use of doxycycline, an antibiotic that kills Wolbachia, has shown to reduce the circulating levels of M. perstans as well

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: July 20, 2016
Last updated: Nov. 13, 2018