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

• Body Cavity Filariasis
• SCF (Serous Cavity Filariasis)

What is Serous Cavity Filariasis? (Definition/Background Information)

• Serous Cavity Filariasis (SCF) refers to a parasitic nematode infection caused either by Mansonella perstans or Mansonella ozardi. The nematodes (roundworms) are transferred from individual to another by different species of Culicoides, the biting midge (a winged insect)
• This type of filariasis affects the serous cavities of the body i.e., the fluid-filled areas of the bodies (excluding blood vessels) that are lined by serous membranes. These can include the chest and abdominal cavities (pleural, pericardial, and peritoneal cavities)
• Serous Cavity Filariasis is one of the least-researched but widely prevalent parasitic diseases in the world. It is classified as a Neglected Tropical Disease (by WHO) and is a disease that is common in certain underdeveloped countries, where people have less access to adequate healthcare
• The infection causes mild symptoms, and many individuals are asymptomatic. Some individuals may develop itchy swellings on skin, along-with joint pain and fatigue from Serous Cavity Filariasis
• Infection of M. perstans or M. ozardi in patients with a compromised immune system may be severe. It can also exacerbate the symptoms of the underlying conditions such as tuberculosis or malaria. Such individuals are prone to developing complications
• Symptomatic patients may be treated using a combination therapy of medications. The prognosis of Serous Cavity Filariasis is good for most individuals. However, those with weak immune systems may take much longer to recover with appropriate treatment

Who gets Serous Cavity Filariasis? (Age and Sex Distribution)

• Individuals of any age and gender may be affected by Serous Cavity Filariasis
• The condition mostly affects individuals living in the nations of South and Central America, and West and Central Africa

What are the Risk Factors for Serous Cavity Filariasis? (Predisposing Factors)

The risk factors for Serous Cavity Filariasis include:

• Living in areas endemic to the condition, or traveling to countries where the infectious nematodes and biting midges are common
• Exposure to infected individuals and infected Culicoides midges
• Individuals with a compromised immune system are more prone to developing an infection

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 Serous Cavity Filariasis? (Etiology)

• Serous Cavity Filariasis is caused by a bite from a species of Culicoides (biting midges of family Ceratopogonidae) that has been infected with either Mansonella perstans or Mansonella ozardi microfilariae (species of infectious larval nematodes or roundworms)
• These midges become infected with microfilarial M. perstans/M. ozardi upon biting an infected individual. The microfilariae develop in the midge and get passed onto an uninfected individual through another bite

The infection is mostly caused by mature adult nematodes and involve/affect the serous body cavities.

What are the Signs and Symptoms of Serous Cavity Filariasis?

The signs and symptoms of Serous Cavity Filariasis are as follows:

• Calabar-swelling: It is the rapid swelling of the skin or tissue located just underneath the skin. The swelling can occur in the hands, face, or forearms and last about 3-4 days
• Itchy skin without a rash
• Joint pain
• Pain in the serous cavities (chest or abdominal cavities)
• Liver pain
• Unexplained fatigue and tiredness

Not all individuals carrying an M. perstans or M. ozardi infection will present noticeable symptoms. Some may have mild symptoms.

How is Serous Cavity Filariasis Diagnosed?

A diagnosis of Serous Cavity Filariasis is undertaken by a qualified healthcare professional.

• As with other filarial diseases, a common method for diagnosing this particular infection is to look for the causative microfilariae circulating in blood. In the case of Serous Cavity Filariasis, microfilariae specific to M. perstans or M. ozardi will be identified
  • Examining blood from a possibly infected individual under a microscope to look for microfilariae
  • Looking for specific proteins released as a response to an infection by M. perstans or M. ozardi. 
• Serosal effusion (fluid) from the serous cavities of the body may also be examined for M. perstans or M. ozardi. This may include pleural fluid, ascitic fluid, etc.
• Other blood tests, as necessary; infected individuals may present elevated white blood cell (WBC) count

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 Serous Cavity Filariasis?

Most cases of infection are generally mild and does not cause any significant complications. In some individuals, Serous Cavity Filariasis may pose serious complications by decreasing the effectiveness of the immune system.

Such complications may include:

• Increased severity of other infections such as tuberculosis, malaria, and HIV infection
• Older adults may present severe symptoms due to weak immunity

How is Serous Cavity Filariasis Treated?

A healthcare professional will determine the best course of action for diagnosis and treatment of Serous Cavity Filariasis. Individuals with strong immunity who are asymptomatic, may not require to be treated. Individuals requiring treatment may be prescribed medications as:

• Medications, such as diethylcarbamazine (DEC), which are used to treat other filarial diseases
• DEC may be used in combination with other medication, such as ivermectin, mebendazole, levamisole, albendazole, or thiabendazole

As the disease is not well studied, oftentimes, a combination of medications may be used with an intent of reducing microfilariae count in blood.

How can Serous Cavity Filariasis be Prevented?

The prevention of Serous Cavity Filariasis may involve the following measures:

• Insect repellant is regarded as the best method to prevent bites from Culicoides midges that cause the disease
• Wearing clothes that have been sprayed with insect repellent during the day, also seems to lessen the risk of contracting the infection from a bite

Unlike other cases of filariasis, Serous Cavity Filariasis is transferred from one individual to another via midges that are tinier than mosquitoes. Therefore, mosquito nets are not an effective preventative measure, as the net holes are usually too large for these midges.

What is the Prognosis for Serous Cavity Filariasis? (Outcomes/Resolutions)

The prognosis for Serous Cavity Filariasis is generally good and the condition is not life-threatening. 

• Individuals other coexisting infections, such as HIV infection, tuberculosis, or malaria, are known to be severely affected
• Individuals with compromised immune system may take much longer to recover

Additional and Relevant Useful Information for Serous Cavity Filariasis:

Although Serous Cavity Filariasis has not been studied in depth, it is extremely common in the endemic areas. A lack of public health services and records in the endemic countries likely contributes to the fact that it is widespread but remains relatively undocumented.