Liverpool School of Tropical Medicine recieves $23 million March 8, 2007, from the Bill and Melinda Gates Foundation to develop a new method to control and treat lymphatic filariasis (tropical lymphedema)
Medical artist shows
how lymphatic filariasis is
caused based on new scientific research
The low-cost management of filarial lymphedema
in rural India using traditional medicine
Filarial lymphedema (also known as elephantiasis) is commonly found in tropical regions throughout the world. It is caused by parasites, which enter the body through mosquito bites. Three parasites are responsible for lymphatic filariasis: Wuchereria bancrofti, Brungia malayi and Brugia timori.
Current research suggest that it is the body's inflammatory response to the parasites - or bacteria riding on top of the parasites - which ultimately causes lymphedema. Some experts, such as Dr. Gerusa Dreyer, author of Basic Lymphoedema Management: Treatment of problems Associated with Lymphatic Filariasis, 2002, have suggested that repeated bacterial infections are the real cause of lymphedema in individuals whose lymphatic systems are already weakened by the parasites.
Lymphatic filariasis, is most commonly recognized by a painful and disfiguring swelling of the limbs and genitals - classic signs of the late stage of the disease. The adult worms live 4-7 years, giving rise to millions of larval forms (microfilariae) which circulate in the lymphatics and blood where they can be taken up by mosquitoes and transmitted to other persons.
Lymphatic filariasis is common in sub-tropical and tropical regions of the world. The World Health Organization estimates that over 120 million people have the condition. Most affected persons are found in Asian and African countries, with the highest numbers in China, India and Indonesia, although there are many cases found in South and Central America as well.
The process of developing lymphatic filariasis can take from two to ten years but the affect of the condition varies from individual to individual depending on their immunity systems and other factors. In some cases, problems never develop even though the parasites are present. In Indonesia and Africa the legs and genital/groin areas are most often affected and swollen; in the Pacific islands the arms are often involved.
Although some experts suggest that physical pain is not generally experienced in chronic lymphatic filariasis, the condition is unsightly. As a result persons with the condition "tend to hide or retreat in the background, because they are tormented by the community." Spectrum of Disease in Lymphatic Filariasis, Felix Partono, Department of Parasitology, University of Indonesia, Jakarta, Indonesia. Presentation at the 1986 Symposium on Filariasis, May 14-16 in Singapore.
which enter the body through mosquito bites.
where 120 million people are affected.
It takes repeated exposure to mosquito carriers before filarial parasites invade an individual's body so tourists are at low risk for acquiring this disorder. People living for extended periods of time in tropical or sub-tropical areas where the disease is common are at greatest risk for infection (source: Centre for Disease Control).
Prevention involves attempting to eliminate the carrier mosquitoes through spraying. Other strategies include preventing the contact of the carriers with humans through the use of mosquito repellent and encouraging those at risk to avoid infested areas near river banks and to wear clothing which cover most of their body.
Once the parasite has invaded an individual's body, drug treatment is used to kill the microfilariae to prevent other individuals in close proximity from also being affected. The drug regime is not effective, however, in eliminating the adult parasite and does not, in itself, prevent lymphedema.
The drug regime involves delivering a single dose of either diethylcarbamazine (DEC) or ivermectin. A two-drug treatment (choosing among albendazole, DEC and ivermectin, administered concurrently) can be more effective than giving the drug alone. Field studies have shown that these once-yearly treatment regimes can interrupt transmission of the infection.
A 1996 study undertaken by GlaxoSmithKline, which donated the two drugs for a trial on the island of Misima, Papua, New Guinea, found a simple treatment could elimiate the disease in effected individuals. The 1996 study was funded by Placer Dome, a Vancouver-based company that operates a mine on the island. (see Science winning the battle against disfiguring disease, by Andre Picard, Globe and Mail, March 16, 2004)
DEC, which is commonly used to treat the disease, cannot be widely used in Africa because it can cause severe side effects in patients who have either onchocerciasis or loaisis -- two diseases that are common in Africa.
Recent research however is now suggesting that antibiotics can be effective in eliminating some types of filarial parasitic infections. See: Wolbachia endosymbiotic bacteria of filarial nematodes. A new insight into disease pathogenesis and control: Taylor MJ, Division of Molecular and Biochemical Parasitology, Liverpool School of Tropical Medicine, Liverpool, UK published in Arch Med Res 2002 Jul-Aug;33(4):422-4. A new approach to the treatment of filariasis.Taylor MJ, Hoerauf A.Liverpool School of Tropical Medicine, Liverpool, UK. published in Curr Opin Infect Dis. 2001 Dec;14(6):717-8.
An international team of researchers has demonstrated the effectiveness of an inexpensive antibiotic, doxycycline, which they say cures most cases of advanced elephantiasis. Dr. Mark Taylor of the Liverpool School of Tropical Medicine in England says the antibiotic kills the parasite through indirect means. It destroys a bacteria inside the filariasis worm, which the parasite relies on to survive. The study on doxycycline and lymphatic filariasis is published in the June 18, 2005 issue of the medical journal, The Lancet.
Once an individual develops lymphedema/elephantiasis, however, many of the conventional treatments such as bandaging, specialized massage, the use of extremity pumps and compression garments must be used to reduce the volume of the effected limb. In severe cases, surgery may be required.
Because of newly available treatment and diagnostic tools, the International Task Force for Disease Eradication has identified filariasis as one of only six diseases considered potentially eradicable. In May 1997 the World Health Assembly adopted Resolution WHA50.29 calling for the elimination of lymphatic filariasis as a public health problem globally. WHO plans to eradicate the disease by 2020.
The Global Alliance to Eliminate Lymphatic Filariasis is a world-wide organization which has risen to this challenge. The Global Alliance to Eliminate Lymphatic Filariasis, for which WHO serves as the secretariat, is a free, non-restrictive partnership forum for the exchange of ideas and coordination of activities, with membership open to all interested parties. For more information on their activities readers can view their web site at: www.filariasis.org.
Information taken from the following sources:
GlaxoSmithKline Lymphatic Filariasis drug donation programme. GlaxoSmithKline (GSK) is a founding partner in the Global Alliance to Eliminate Lymphatic Filiariasis and is donating its albendazole tablets free of charge until the disease is eliminated, a 20 year commitment estimated at 5-6 billion tablets or US$1 billion.
PRNewswire -- Merck & Co., Inc. announcement, Oct. 22, 1998 Merck Announces Expansion of World's Largest Donation Program by Adding Lymphatic Filariasis (Elephantiasis)to the Mectizan(R) Donation Program In Africa
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Last revised May 25, 2007.