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Lymphatic Filariasis

Last updated Nov. 1, 2018

Approved by: Krish Tangella MD, MBA, FCAP

Lymphatic Filariasis is a disease caused by parasitic roundworms of 3 different types. It is most commonly caused by Wuchereria bancrofti, and may also be caused by Brugia malayi and Brugia timori.


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

  • Elephantiasis
  • Elephantiasis Tropica
  • LF (Lymphatic Filariasis)
  • Tropical Eosinophilia (Lymphatic Filariasis)

What is Lymphatic Filariasis? (Definition/Background Information)

  • Lymphatic Filariasis is a disease caused by parasitic roundworms of 3 different types. It is most commonly caused by Wuchereria bancrofti, and may also be caused by Brugia malayi and Brugia timori
  • It is an infection of the lymphatic system that may result in severe disfigurement as a result of swelling in the limbs and/or scrotum. Lymphatic Filariasis is prevalent in warm climates with high exposure to mosquitoes
  • Mosquitoes inject the microfilarial roundworms, which include W. bancrofti, B. malayi, or B. timori upon biting. These microfilariae (or microscopic larval worms) then mature into adult worms within the lymphatic system of the individual who is bitten
  • Individuals with minor infections may present with just fever, while individuals with severe infections may develop elephantiasis (severe swelling of a limb). There are slight variations in the presentation of Lymphatic Filariasis depending on which type of parasitic roundworm causes the infection. All infections share common characteristics of the larval worms, which is in being spread from individual to individual via mosquitoes
  • In most cases, Lymphatic Filariasis can be treated using medications to eliminate the parasitic worms within the body. The prognosis for Lymphatic Filariasis is generally good, as most individuals are asymptomatic. For individuals with elephantiasis, it is important to treat both the physical symptoms as well as the mental/emotional stress it causes
  • Even though the disease is common in tropical areas around the world, Lymphatic Filariasis can be prevented. Important preventative measures include destroying the breeding grounds of the mosquitoes, sleeping inside mosquito nets, and using suitable repellant creams to avoid bites

Who gets Lymphatic Filariasis? (Age and Sex Distribution)

  • While Lymphatic Filariasis does not show an age or sex preference, it tends to present differently in males in females. The worms that cause Lymphatic Filariasis tend to incubate in the body for months, possibly years
    • In males, the earliest it tends to present is at around 11 years of age
    • In females, the onset of illness is usually around 13 years
  • This disease is common to tropical and subtropical regions of the world, and it mostly affects the races and ethnicities that live in these climates

What are the Risk Factors for Lymphatic Filariasis? (Predisposing Factors)

The risk factors for Lymphatic Filariasis include:

  • Living in areas where mosquitos thrive and can transmit the infectious worms
  • Being exposed to unsanitary conditions: Lymphatic Filariasis has a notable socioeconomic distribution as well. The worms thrive in unsanitary conditions and as such affect individuals living in impoverished areas with poor living situations
  • Lymphatic Filariasis is endemic to tropical and sub-tropical areas. This includes populations in countries of the Caribbean, South America, Africa, South Asia, and Southeast Asia.
  • As the body must accumulate many mosquito bites to develop the disease, individuals must live in a region endemic to the disease for many years before manifesting signs and symptoms of Lymphatic Filariasis

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones 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 Lymphatic Filariasis? (Etiology)

Lymphatic Filariasis is caused by filarial worm species that infect a human host. The adult worms live in the lymphatic system and produce thousands of larval microfilariae.

  • These microfilariae mature into adult worms before they are passed onto another individual via a mosquito bite. The worm species causing infection include:
    • Wuchereria Bancrofti
    • Brugia malayi
    • Brugia timori
  • The species of mosquito that transmit the worms from human to human vary by country or geographical region
    • Anopheles is the most common mosquito species in Africa
    • In the Americas, Culex quinquefasciatus is more common
    • Aedes and Mansonia species are prevalent in Asia

What are the Signs and Symptoms of Lymphatic Filariasis?

The signs and symptoms of Lymphatic Filariasis include:

  • Fever
  • Body aches and pains
  • Enlarged lymph nodes or lymphadenopathy
  • Lymphedema (swelling of the extremities with fluid): It may affect the legs, arms, and breast tissue
  • Persistent and chronic edema may lead to toughening and thickening of the skin surrounding the swollen limb
  • Hydrocele (swelling of the scrotum with fluid)
  • Increased risk for bacterial infection of the skin and lymphatic system

Lymphatic Filariasis may present with slightly varied symptoms depending on what species of roundworm has caused the infection:

  • W. bancrofti infections may affect the legs and genitalia (specifically the scrotum of males or, to a lesser extent, the vulva of females)
  • B. malayi infections may lead to edema in the legs below the knee

Chronic lymphedema may lead to signs associated with blockage of lymphatic vessels including:

  • Swelling of the scrotum
  • Large lymphatic vessels
  • Enlargement and thickening of the limbs
  • Lymph in the urine

In general, the parasites prefer the lymphatic system localized to the scrotum in males and the extremities in females, although it is seen in the extremities in males as well. Infection in these areas causes the limbs or scrotum to swell with fluid in a condition known as edema.

How is Lymphatic Filariasis Diagnosed?

A complete physical examination performed by a healthcare professional along with a full medical history is the first step in diagnosing Lymphatic Filariasis.

  • Blood test: A sample of blood may be examined under microscope for the presence of the microfilariae responsible for the disease. The worms move around the lymphatic system at night, so the sample is typically collected at night
  • Tests run against antibodies specific parasitic infection may be undertaken as well. However, this method has been somewhat criticized due its tendency to register a positive test for multiple species of parasitic worm, which generally affects the diagnosis of the exact species causing Lymphatic Filariasis infection
  • Individuals with symptomatic Lymphatic Filariasis will have increased concentrations of antifilarial IgG4 (a type of protein) in their blood. Detection of this protein can be part of a successful diagnosis
  • Cases of Lymphatic Filariasis due to W. bancrofti infections can be easily detected by a circulating filarial antigen (CFA) test
    • The CFA detection method returns a positive result when it encounters an antigen specific to W. bancrofti
    • It is also possible to determine if lymphedema was caused as a result of W. bancrofti using this test, even if no circulating microfilariae is present
  • X-rays of the affected limbs can be useful in diagnosing Lymphatic Filariasis
  • An ultrasound scan can be performed, which is helpful in diagnosing the presence of adult worms in the lymphatic vessels surrounding the scrotum, breast tissue, and behind the organs

Many clinical conditions may 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 Lymphatic Filariasis?

  • The complications of Lymphatic Filariasis arise from severe cases that lead to elephantiasis and may result in loss of limb function
  • In addition to physical complications, Lymphatic Filariasis may have emotional and societal consequences as well. Some societies are known to ostracize individuals who have contracted the infection

How is Lymphatic Filariasis Treated?

Generally, the treatment decisions for Lymphatic Filariasis will be made after consultation with a qualified healthcare professional.

  • Lymphatic Filariasis is generally treated with diethylcarbamazine (DEC). DEC attacks the larval microfilariae and can also kill some of the adult worms
  • Mectizan is another anti-parasitic drug that has been shown to be effective against Lymphatic Filariasis
  • Albendazole is a drug commonly given to treat parasitic intestinal infections in children. When used alongside Mectizan or DEC, it is shown to reduce numbers of adult worms and microfilariae in blood

The aforementioned drugs do not reverse lymphatic edema (swelling of the limbs) or hydrocele (swelling of the scrotum). Individuals with clinical symptoms of Lymphatic Filariasis are managed through other means.

  • For those exhibiting swelling of the limbs, the condition can be improved by self-care steps taken by the individual that may include:
    • Proper hygiene techniques: These include washing the affected area with soap and water at least twice a day
    • Exercise: In addition to exercising (gently) the affected limb, those with swelling in the limbs should keep the limb elevated while sleeping
    • Management and care of wounds: Antibiotic creams and ointments should be used on small cuts and abrasions
  • Treatment for Lymphatic Filariasis involving hydrocele normally requires surgery

Attention must be given to the affected individual’s psychological state as well. Oftentimes, individuals presenting with lymphedema may be shunned from their social groups. Therefore, it is important to give suitable supportive care and assurance to such individuals.

How can Lymphatic Filariasis be Prevented?

Prevention of Lymphatic Filariasis is best achieved by limiting mosquito bites and eliminating their breeding areas.

  • The mosquitos responsible for transmitting the microfilariae are most active at dusk and dawn. During these times, it is advised to apply insect repellent and wear clothing that covers the arms and legs
  • When possible, a mosquito net should be used while sleeping. Sleeping in cool areas is also advised

Within the last 20 years, there have been massive global efforts towards eliminating Lymphatic Filariasis.

  • These methods center on providing at-risk populations with yearly supplies of the drugs that target the microfilariae
  • Reducing the levels of microfilariae in blood also impacts the severity of mosquito bites. If there is less microfilaria in blood, there is less of a chance that mosquitoes will transmit the infection from one individual to another individual

What is the Prognosis of Lymphatic Filariasis? (Outcomes/Resolutions)

  • Many individuals infected with Lymphatic Filariasis may not present any kind of symptoms. In such cases, the prognosis is good. However, they are at risk for passing the condition to other individuals when they are bitten by mosquitoes
  • For individuals who display clinical symptoms of Lymphatic Filariasis, it is important that they receive treatment and practice good habits in taking care of the affected area (limbs). Individuals, who maintain proper hygiene (keep the area clean), exercise, and check for wounds and sores, can greatly reduce progression of the condition

Additional and Relevant Information for Lymphatic Filariasis:

  • Huge strides are being made to eliminate Lymphatic Filariasis from the world. Through the combined efforts of many developed nations, countries in need are receiving the drugs necessary to reduce the microfilariae population to non-disease causing levels
  • Lymphatic Filariasis is considered to be a Neglected Tropical Disease (NTD); a disease that is not seen in developed nations, but continues to affect individuals living in poorer countries. Positive steps have been made in its eradication, with countries like China having all but eliminated the disease
  • About 120 million people living in tropical and sub-tropical climates are infected with Lymphatic Filariasis. Of these people, 25 million are males exhibiting hydrocele (swelling of the scrotum) and 15 million are female with edema (swelling) in the limbs

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: June 7, 2016
Last updated: Nov. 1, 2018