Everything about Filariasis totally explained
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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.
Presentation
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 a mosquito bite. 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. Infection by
Onchocerca volvulus and the migration of its microfilariae through the
cornea is a major cause of blindness (
Onchocerciasis). This disease isn't known to be fatal, although it can obviously cause a fair amount of pain to the infected.
Incidence/prevalences
Filariasis is endemic in tropical regions of
Asia,
Africa,
Central and
South America with 120 million people infected.
In endemic areas of the world (for example,
Malaipea in
Indonesia), up to 54% of the population may have microfilariae in their blood.
History
Lymphatic Filariasis is thought to have affected humans since approximately 1500-4000 years ago, though an exact date for its origin is unknown. The first clear reference to the disease occurs in ancient Greek literature, where scholars discuss diagnosis of lymphatic filariasis vs. diagnosis of similar symptoms that can result from
leprosy.
The first documentation of symptoms occurred in the 16th century, when
Jan Huygen Linschoten wrote about the disease during the exploration of Goa. Soon after, exploration of other parts of Asia and Africa turned up further reports of disease symptoms. It wasn't until centuries later than an understanding of the disease began to develop.
In 1866,
Timothy Lewis, building on the work of
Jean-Nicolas Demarquay and
Otto Henry Wucherer, made the connection between microfilariae and elephantiasis, establishing the course of research that would ultimately explain the disease. Not long after, in 1876,
Joseph Bancroft discovered the adult form of the worm, and finally in 1877 the life cycle involving an arthropod vector was theorized by
Patrick Manson, who proceeded to demonstrate the presence of the worms in mosquitoes. Manson incorrectly hypothesized that the disease was transmitted through skin contact with water in which the mosquitoes had laid eggs. In 1900, George Carmichael Low determined the actual transmission method by discovering the presence of the worm in the proboscis of the mosquito vector.
Diagnosis
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
Medicines to treat lymphatic filariasis are most effective when used soon after infection, but they do have some toxic side effects. In addition, the disease is difficult to detect early. Therefore, improved treatments and laboratory tests are needed.
Once Filaria is attacked, the patients are likely to get fever once in a year or two with shivering. They are also administered Florocid injections
Antibiotics as a possible treatment
In 2003 it was suggested that the common antibiotic
doxycycline might be effective in treating elephantiasis.
The parasites responsible for filariasis have a population of symbiotic bacteria,
Wolbachia, that live inside the worm. When the symbiotic bacteria are killed by the antibiotic, the worms themselves also die.
Clinical trials in June 2005 by the Liverpool School of Tropical Medicine reported that an 8 week course almost completely eliminated microfilariaemia.
- Diethylcarbamazine Citrate (Hetrazan)
The good drugs of choice for killing adult filarial worm are Albendazole (broad spectrum anti-helminthic) and Ivermectin. A combination of DEC & Albendazole or DEC & Ivermectin is found more effective
Further Information
Get more info on 'Filariasis'.
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