Lymphatic Filariasis is a parasitic and infectious tropical disease, caused by three thread-like parasitic filarial 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.
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………………………….Filariasis, Classification & external resources
Filaria is a long, thread-like roundworm called Wuchereria Bancrofti that lives as a parasite in the bodies of human beings and animals. The male worm is shorter than the female and it has a curved tail. This is mainly found in Central Africa, Asia and the Southwest Pacific.
The young worms can be seen in the blood near the body surface of the host or the animal in which the larvae live. When a mosquito bites an infected person at night, it takes up the larvae with the blood. These larvae develop in the mosquito, near the mouth. Then when the insect bites a man or another animal the larvae enter the wound and infect a new host.
The adult worms live in the lymph – a body fluid. When the worms block the flow of lymph, a disease called Elephantiasis results. This disease is characterised by severe swelling of the limbs, usually the legs. Sometimes it even can affect the breast or the scrotum.
This gross swelling in the legs and other parts of the body and the thickening of the skin due to blockage fo the vessels of the lymphatic system is called Elephantiasis.
The most spectacular symptom of lymphatic filariasis is elephantiasisâ€”thickening of the skin and underlying tissuesâ€”which was the first disease discovered to be transmitted by insects. Elephantiasis is caused when the parasites lodge in the lymphatic system.
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.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).
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.
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 was not 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
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
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.
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)
Prevention:While medicines are available to treat filaria, the gross swelling of the leg makes a person look noticeable and ugly. Hence, it is better to protect oneself from the bites of filaria mosquitoes. Use aerosols, mosquito repellenets, creams, mats coils, nets and prevent breeding of mosquitoes with better practice of hygiene and sanitation.
Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.