Lymphatic Filariasis
(also known as LF or Elephantiasis)

Defining the Disease

What is Lymphatic Filariasis?

CDC illustration showing the life cycle of the Wuchereria bancrofti mosquito
(click to zoom)

Lymphatic Filariasis: (lim-fat-ik fĭl’ə-rī’ə-sĭs) is a parasitic disease endemic throughout the world, but found primarily in Africa, India, and the Pacific Islands. In Africa, LF is caused by the parasitic, threadlike worm Wuchereria bancrofti, and is transmitted to humans through the bites of mosquitoes. Long-term infection with LF can lead to painful and disfiguring chronic enlargement of the arms, legs, breasts, and genitals of people of all ages. It can cause severe swelling in the testicles, a condition known as hydrocele, which can be reversed surgically. The disease is commonly called “elephantiasis” because of the elephant-like appearance of swollen limbs in those most severely affected. Infection with LF can cause severe physical and psychological disability. In addition, men with hydroceles often suffer from sexual dysfunction. Like river blindness, LF also has a significant economic impact when productivity is reduced due to the disabilities caused by the disease.

LF Disease Burden

The World Health Organization estimates that worldwide there are:

0 M
At Risk for Lymphatic Filariasis Infection
0 M
People Currently Infected with LF
0 M
With Symptoms From LF Infection

Clinical Manifestations

In the first year of infection, a person may experience few or mild symptoms. However, with repeated infections over several years, a person may develop outward manifestations of the disease. Through a variety of mechanisms, the adult worms in the lymphatic system alter the structure and functioning of the lymphatic vessels, resulting in one or more of the following conditions:

Photo of a smiling man sitting outdoors under a tree. His legs are drawn up and one of them is badly swollen from lymphatic filariasis.
In Malawi, Maxwell's LF-swollen leg makes it difficult for him to work.
  • > Adenolymphangitis: Acute episodes of adenolymphangitis (ADL) is a common clinical manifestation of LF, characterized by recurrent attacks of fever associated with inflammation of the lymph nodes and/or lymph vessels.
  • > Lymphedema: abnormal accumulation of lymph fluid in the tissues, causing swelling of a limb or other parts of the body which are then more susceptible to repeated bacterial infections.
  • > Elephantiasis: disabling and disfiguring chronic lymphedema of the limbs, breasts, or genitals, accompanied by marked thickening of the skin.
  • > Hydrocele: fluid-filled, balloon-like enlargement of the sacs around the testes which, if left untreated, can destroy the testicles.

Treatment

Treating people in endemic districts eliminates microfilariae from the blood of infected individuals, thereby interrupting transmission of infection by mosquitoes. WHO recommends > 5 years of mass drug administration (MDA) with preventive chemotherapy to reduce microfilariae from the bloodstream and to prevent transmission. The medicines used are albendazole co-administered with Mectizan® in countries co-endemic with river blindness, or diethylcarbamazine (DEC) co-administered with albendazole in other endemic countries. Some countries are eligible for a new treatment strategy, which will accelerate LF elimination through the co-administration of ivermectin (Mectizan) + DEC + albendazole (a “triple therapy” known as IDA). In areas where Loa loa and LF are co-endemic, treatment with albendazole (400 mg) alone should be given, preferably twice per year, to stop the spread of LF.

Status of MDA for Lymphatic Filariasis in 2022

Status of MDA for Lymphatic Filariasis in 2022

Note: Lymphatic filariasis is widespread and different environments call for different medications (see “Treatment” above). Medication(s) used in each region is indicated in parentheses next to the region’s name.

KEY:
I = Mectizan (ivermectin)
D = diethylcarbamazine (DEC)
A = albendazole

MDA Not Started or Not Implemented
MDA Started but Not at Scale
MDA Scaled to All Endemic IUs*
In Post-MDA Surveillance
LF Eliminated as a Health Problem
  • Gabon (IA)
  • Angola (IA)
  • Central African Republic (IA)
  • Madagascar (DA, IDA)
  • Nigeria (IA)
  • Papua New Guinea (DA, IDA)
  • Sudan (IA)
  • American Samoa (DA, IDA)
  • Burkina Faso (IA)
  • Chad (IA)
  • Comoros (DA)
  • Congo (IA)
  • Côte d’Ivoire (IA)
  • Democratic Republic of the Congo (IA)
  • Equatorial Guinea (IA)
  • Ethiopia (IA)
  • Fiji (DA, IDA)
  • French Polynesia (DA)
  • Ghana (IA)
  • Guinea (IA)
  • Guinea-Bissau (IA)
  • Guyana (DA, IDA)
  • Haiti (DA, IDA)
  • India (DA, IDA)
  • Indonesia (DA, IDA)
  • Kenya (DA, IDA)
  • Liberia (IA)
  • Malaysia (DA, IDA)
  • Federated States of Micronesia (DA)
  • Mozambique (IA)
  • Myanmar (DA)
  • Nepal (DA)
  • New Caledonia (DA)
  • Niger (IA)
  • Philippines (DA)
  • Samoa (DA, IDA)
  • Senegal (IA)
  • Sierra Leone (IA)
  • South Sudan (IA)
  • Tanzania (IA)
  • Tuvalu (DA, IDA)
  • Zambia (DA)
  • Zimbabwe (DA)
  • Benin (IA)
  • Brazil (DA)
  • Brunei Darussalam (DA)
  • Cameroon (IA)
  • Dominican Republic (DA)
  • Eritrea (DA)
  • Mali (IA)
  • São Tomé and Príncipe (DA, IDA)
  • Timor-Leste (DA, IDA)
  • Uganda (IA)
  • Bangladesh (DA)
  • Cambodia (DA)
  • Cook Islands (DA)
  • Egypt (DA, IDA)
  • Kiribati (DA)
  • Lao PDR (DA)
  • Malawi (IA)
  • Maldives (DA)
  • Marshall Islands (DA)
  • Niue (DA)
  • Palau (DA)
  • Sri Lanka (DA)
  • Thailand (DA)
  • Togo (IA)
  • Tonga (DA)
  • Vanuatu (DA)
  • Vietnam (DA)
  • Wallis and Futuna (DA)
  • Yemen (IA)

*Implementation Units

Source: World Health Organization

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