A chronic disease of the lymphatic system caused by the Wuchereria bancrofti, Brugia (B) malayi, or B. timori, the three species of Filarioidea.

Mosquitoes spread the disease. As the mosquito bites, the infectious larvae enter the body and make their way into the lymphatics. In the lymphatics, the larvae develop into adult worms within 6 to 12 months. Females produce embryos of filariae that circulate in the blood. Bancroftian filariasis is most frequently seen in tropical and subtropical areas of Africa, Asia, the Pacific, and the Americas, including parts of the Caribbean. Brugian filariasis is only seen in South and Southeast Asia.

Infection may occur without manifestations. Acute inflammatory filariasis presents episodes lasting 4 to 7 days accompanied by the following manifestations: fever; acute inflammation of the lymph nodes or lymph glands; and progressively worsening lymphangitis or acute inflammation of the spermatic cord and epididymis. Brief periods of swollen lymph nodes of an affected limb may occur causing an abscess that drains externally leaving a scar.

Detecting the microfilariae in blood via microscope establishes the diagnosis. In addition, living adult worms can be seen in widened lymphatics by ultrasound.

Treatment can be difficult. It includes a medication, diethylcarbamazine (DEC), that kills microfilariae, but it may not kill all of the adult worms. Another medication, ivermectin, rapidly decreases the microfilaremia levels, and may also hinder larval development in mosquitoes. However, it does not kill adult worms, and is not effective against all filariasis parasites. Acute attacks usually resolve spontaneously, and antibiotics may be warranted to control secondary infections. In addition, treatment of chronic obstructive filarial disease consists of elevation of the infected limb, use of elastic stockings, and local foot care. Surgical decompression may also provide some relief.

Chronic filarial disease often develops after many years without the patient's awareness. Most cases result in lymphatic widening without noticeable symptoms. However, chronic inflammatory reactions to adult worms may result in chronic swelling of the lymph nodes at the affected body area or in the scrotal area producing fluid-filled sacs (hydroceles). Hyperkeratosis and an amplified local vulnerability to bacterial and fungal infections lead to elephantiasis. Other chronic forms may lead to the presence of digestive products and absorbed fats in the urine, chyluria, and chyloceles. These same products can be found in the serous membrane surrounding the testis.

1. May be entitled to special monthly compensation where the Veteran has a single service-connected disability rated as 100% and/or other requirements/qualifications under 38 CFR §3.350 [Special monthly compensation ratings]. Also reference 38 CFR 3.155(d)(2).

2. This disease shall be granted service connection although not otherwise established as incurred in or aggravated by service if manifested to a compensable degree within the applicable time limits under §3.307 following service in a period of war or following peacetime service on or after January 1, 1947, provided the rebuttable presumption provisions of §3.307 are also satisfied [38 CFR 3.309(a) [Disease subject to presumptive service connection], [chronic disease].

3. This disease shall be granted service connection as a result of tropical service, although not otherwise established as incurred in service if manifested to a compensable degree within the applicable time limits under §3.307 or §3.308 following service in a period of war or following peacetime service provided the rebuttable presumption provisions of §3.307 are also satisfied [38 CFR 3.309(b) ].

Rate under the appropriate body system any residual disability of infection, which includes, but is not limited to, epididymitis, lymphangitis, lymphatic obstruction, or lymphedema affecting extremities, genitals, and/or breasts. (38 CFR §4.88b [Schedule of ratings-infectious diseases, immune disorders and nutritional deficiencies]