Lymphatic Filariasis / Elephantiasis Wuchereria bancrofti & Brugia malayi.
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Transcript of Lymphatic Filariasis / Elephantiasis Wuchereria bancrofti & Brugia malayi.
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Lymphatic Filariasis /
Elephantiasis
Wuchereria bancrofti & Brugia malayi
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What is it? Wuchereria bancrofti and Brugia malayi
are filarial nematodes Spread by several species of night -
feeding mosquitoes Causes lymphatic filariasis, also known
as Elephantiasis Commonly and incorrectly referred to as
“Elephantitis”
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+
+ = ?
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Definitive Host
Humans are the definitive host for the worms that cause lymphatic filariasis
There are no known reservoirs for W.bancrofti.
B.malayi has been found in macaques, leaf monkeys, cats and civet cats
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Intermediate Host W.bancrofti is transmitted by
Culex, Aedes, and Anopheles species
B.malayi is transmitted by Anopheles and Mansonia species.
Anopheles
Aedes
CulexMansonia
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Geographic Range Lymphatic filariasis occurs in the tropics of
India, Africa, Southern Asia, the Pacific, and Central and South America.
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Lymphatic Filariasis by the numbers Endemic in 83 countries 1.2 billion at risk More than 120 million people infected More than 25 million men suffer from
genital symptoms More than 15 million people suffer from
lymphoedema or elephantiasis of the leg
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Morphology - W.bancrofti W.bancrofti is a sexually
dimorphic species. The adult male worm is long and
slender, between four and five centimeters in length, a tenth of a centimeter in diameter, and has a curved tail.
The female is six to ten centimeters long, and three times larger in diameter than the male.
Microfilariae are sheathed, and approximately 245 to 300 µm in length.
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Morphology - B.malayi B.malayi microfilariae are slightly
smaller than those of W.bancrofti. Microfilariae are sheathed, and
about 200 to 275 µm. Not much is known about the adult
worms, as they are not often recovered
One distinctive feature of B.malayi is that the microfilarial nuclei extends to the tip of the tail
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Wuchereria Life Cycle
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Symptoms 1. Asymptomatic: patients have hidden
damage to the lymphatic system and kidneys. 2. Acute: attacks of ‘filarial fever’ (pain and
inflammation of lymph nodes and ducts, often accompanied by fever, nausea and vomiting) increase with severity of chronic disease.
3. Chronic: may cause elephantiasis and hydrocoele (swelling of the scrotum) in males or enlarged breasts in females.
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Diagnosis The standard method for diagnosing active
infection is the identification of microfilariae by microscopic examination
However, microfilariae circulate nocturnally, making blood collection an issue
A “card test” for parasite antigens requring only a small amount of blood has been developed Does not require laboratory equipment Blood drawn by finger stick
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Control As with malaria, the most effective method
of controlling the spread of W.bancrofti and B.malayi is to avoid mosquito bites
The CDC recommends that anyone in at-risk areas:
Sleep under a bed net Wear long sleeves and trousers Wear insect repellent on exposed skin, especially
at night
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Vector control Covering water-storage containers and
improving waste-water and solid-waste treatment systems can help by reducing the amount of standing water in which mosquitoes can lay eggs.
Killing eggs (oviciding) and killing or disrupting larva (larviciding) in bodies of stagnant water can further reduce mosquito populations.
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Treatment Treatment of filariasis involves two
components: Getting rid of the microfilariae in people's
blood Maintaining careful hygiene in infected
persons to reduce the incidence and severity of secondary (e.g., bacterial) infections.
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Drugs, Drugs, Drugs! Anti-filariasis medicines commonly used include: Diethylcarbamazine (DEC)
reduces microfilariae concentrations kills adult worms
Albendazole kills adult worms
Ivermectin kills the microfilariae produced by adult worms
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…And more drugs! The disease is usually treated with single-
dose regimens of a combination of two drugs, one targeting microfilariae and one targeting adult worms (i.e.,either diethylcarbamazine and albenadazole, or ivermectin and albendazole
In some areas, DEC laced table salt is used as a prophylactic
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Treatment 2: Manchester United 0 If a high enough coverage of anti-filariasis drug
treatment can be achieved (treating greater than 80% of the people in a community), the disease can be eradicated from an area.
Attempts to eliminate the disease are being helped considerably by Merck and Co., which is donating ivermectin to treatment efforts, and Smith Kline Beecham, which is donating albendazole.
The Gates Foundation has also donated millions towards eliminating lymphatic filariasis
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Elimination programs
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Finally… http://youtube.com/watch?v=SkIryQ6Paqg