Filariasis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Lymphatic Filariasis (Philariasis) is a parasitic and infectious tropical disease, caused by three thread-like parasitic filarial worms called nematode worms, Wuchereria bancrofti, Brugia malayi, and Brugia timori, all transmitted by mosquitoes. It is extremely rare in Western countries. Loa loa is another filarial parasite of humans, transmitted by the deer fly.
Historical Perspective
Filariasis is believed to be found since the 16th century as Jan Huygen Linschoten put an overall idea about the disease when he went to Goa. Moving forward through the 19th century there was many discoveries regarding filariasis and the infective worms and the arthropod vectors. In 1866, the detection of the microfilariae in urine and blood. 10 years later in 1876, Joseph Bancroft discovered the adult worm which is responsible for the infection and named after that as Wuchereria Bancrofti. Through the next years till 1900s more discoveries and description of the life cycles of the worms had been known.[1]
Classification
Filariasis disease can be classified based on the site of infection. It is caused by different types of roundworms that infect particular site in the body. A group of these worms infect the lymphatic vessels causing lymphatic filariasis. Others infect serous cavities and subcutaneous tissues. It can be also classified into acute and chronic filariasis.
Causes
Filariasis is caused by nematodes (roundworms) that inhabit the lymphatics and subcutaneous tissues. Wuchereria bancrofti and Brugia malayi are the main cause of filariasis.
Epidemiology and Demographics
Filariasis is endemic in tropical regions of Asia, Africa, Central and South America with 120 million people infected. In endemic areas of the world (e.g., Malaipea in Indonesia), up to 54% of the population may have microfilariae in their blood.[2]
Diagnosis
History and Symptoms
The most spectacular symptom of lymphatic filariasis is elephantiasis—thickening of the skin and underlying tissues—which was the first disease discovered to be transmitted by insects. Elephantiasis is caused when the parasites lodge in the lymphatic system. Elephantiasis affects mainly the lower extremities, whereas ears, mucus membranes, and amputation stumps are rarely affected; however, it depends on the species of filaria. W. bancrofti can affect the legs, arms, vulva, breasts, while Brugia timori rarely affects the genitals.
Laboratory and Findings
The diagnosis is made by identifying microfilariae on a Giemsa stained thick blood film. Blood must be drawn at night, since the microfilaria circulate at night, when their vector, the mosquito, is most likely to bite. There are also PCR assays available for making the diagnosis.
Treatment
Medical Therapy
The recommended treatment for patients outside the United States is albendazole (a broad spectrum anthelmintic) combined with ivermectin.[3] A combination of diethylcarbamazine (DEC) and albendazole is also effective. All of these treatments are microfilaricides; they have no effect on the adult worms.
References
- ↑ Chandy A, Thakur AS, Singh MP, Manigauha A (2011). "A review of neglected tropical diseases: filariasis". Asian Pac J Trop Med. 4 (7): 581–6. doi:10.1016/S1995-7645(11)60150-8. PMID 21803313.
- ↑ Aupali T, Ismid IS, Wibowo H; et al. (2006). "Estimation of the prevalence of lymphatic filariasis by a pool screen PCR assay using blood spots collected on filter paper". Tran R Soc Trop Med Hyg. 100 (8): 753&ndash, 9.
- ↑ U.S. Centers for Disease Control, Lymphatic Filariasis Treatment, retrieved 2008-07-17