Lymphatic filariasis (Elephantiasis)

Lymphatic filariasis, commonly known as elephantiasis, is a painful and profoundly disfiguring disease. It is caused by infection with parasites classified as nematodes (roundworms) of the family Filariodidea that are transmitted through the bites of infected mosquitos. Mosquito-transmitted larvae are deposited on the skin from where they can enter the body. The larvae then migrate to the lymphatic vessels where they develop into adult worms, thus continuing a cycle of transmission.

In communities where filariasis is transmitted, all ages are affected. While the infection may be acquired during childhood its visible manifestations such as limbs oedema may occur later in life, causing temporary or permanent disability. In endemic countries, lymphatic filariasis has a major social and economic impact.

Lymphatic filariasis affects over 120 million people in 72 countries throughout the tropics and sub-tropics of Asia, Africa, the Western Pacific, and parts of the Caribbean and South America.

Whereas the disease was once thought to affect only adults, it now appears that most infections are acquired in childhood. Initial infection is followed by a long period of subclinical disease, which progresses in later life to clinically manifest disease. Lymphatic filariasis can cause of variety of clinical manifestations, that can be grouped in three categories: acute attacks, lymphoedema/elephantiasis and hydrocoele.

The adult filarial worms cause inflammation of the lymphatic system leading to lymphatic vessel damage, even in asymptomatic people, and lymphatic dysfunction, which predispose the lower limbs in particular to recurrent bacterial infection. These secondary infections provoke “acute attacks”, which are the commonest symptom of lymphatic filariasis and play an important role in the progression of lymphoedema. Acute attack is usually associated with local pain and swelling and with fever and chills.

Lymphoedema and its more advanced form, elephantiasis, occur primarily in the lower limbs and are commoner in women. In its most advanced form, elephantiasis may prevent people from carrying out their normal daily activities. Lymphatic filariasis may also evolve towards a genital disease (hydrocoele) that is characterized by a swelling of the scrotum and penis.

The vast majority of infected people are asymptomatic, but virtually all of them suffer from damages to the lymphatic system and the kidneys, and from an altered body's immune system.

People infected with filariasis who have microfilaraemia or a positive antigen test should receive antifilarial drug treatment to eliminate microfilariae. Unfortunately, the medicines available have limited effect on adult worms. Treatment also involves the management of morbidity and disability prevention (MMDP) that includes simple hygiene measures, such as basic skin care and exercise, to prevent acute attacks and progression of lymphoedema to elephantiasis. For management of hydrocoele, surgery may be appropriate. MMDP includes also psychological and socioeconomic support for people with disabling conditions to ensure that they have equal access to rehabilitation services and opportunities for health, education and income. Activities beyond medical care and rehabilitation include promoting positive attitudes towards people with disabilities, preventing the causes of disabilities, providing education and training, supporting local initiatives, and supporting micro- and macro-income-generating schemes.

Preventive chemotherapy is used at the community level to  eliminate microfilariae from the blood of infected individuals in order to interrupt transmission of infection by mosquitoes.