Epidemiology
There are several types of filariasis. The term is used to designate diseases caused by pathogenic worms called filaria.
Lymphatic filariasis
This disease is caused by two species of worms, Wuchereria bacroft and Brugia malayi, and is transmitted by the bite of female mosquitoes of the genera Anopheles, Aedes and Culex.
This form of filariasis is one of the main parasitic tropical diseases. It threatens over 1 billion people in approximately 80 countries.
Of the 120 million persons who are already infected, over 40 million are seriously handicapped or disfigured by the disease. One third of infected persons live in India, one third in Africa and the rest mainly in Southern Asia, the Pacific and the Americas, and the number of cases is constantly rising.
Loa loa filariasis
This disease is transmitted by horsefly bites. It is present in Central Africa.
Onchocerciasis
Also called "river blindness", this disease is caused by the filarius "Onchocerca volvulus" and is transmitted by mosquito (black fly) bites.
Symptoms
Lymphatic filariasis
The disease is generally acquired in early childhood and can take several years to become evident. In many persons, there are no external clinical signs, but infected persons present with a latent lymphatic disease and kidney damage.
The most serious symptoms of the chronic disease generally appear in adults:
- genital damage: hydrocele, elephantiasis of the penis and scrotum, elephantiasis of the vulva,
- elephantiasis of the leg, arm or breasts.
Loa loa filariasis
The worm migrates under the skin and may provoke brief oedema (lasting a few hours), which moves and itches. It is mainly located on the insides of the upper limbs. Neurological, cardiac and renal complications are sometimes observed.
Onchocerciasis
This disease causes itching nodules under the skin, disseminated all over the body.
Treatment
Treatment consists of:
1. Eliminating the microfilaria from the blood of infected persons in order to interrupt the transmission of infection by the mosquito
A single dose of DEC (diethylcarbamazine).
To fight adult filaria (the elimination of which is necessary for complete recovery from the infection): albendazole or DEC.
2. Fighting secondary bacterial infections of the tissues
Careful hygiene of the affected limbs and additional measures to reduce the infection as much as possible and promote lymphatic flow.
These measures produce a spectacular reduction in the frequency of acute attacks of inflammation ("filarial fever") and a surprising improvement in the elephantiasis itself.
Prevention
1. Vaccination
There is no vaccine.
2. Prevention of insect bites
Prevention is mainly based on :
- wearing ample clothing that covers the body,
- the use of appropriate repellent products for the body and insecticide clothing (Moustifluid High Protection Tropical Zones and Moustifluid Lotion For Fabrics and Clothing Tropical Zones),
- and repellent-sprayed mosquito nets (Moustifluid Lotion For Fabrics and Clothing Tropical Zones).