Lymphatic Filariasis /

Elephantiasis

Wuchereria bancrofti & Brugia malayi

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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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

Intermediate Host W.bancrofti is transmitted by

Culex, Aedes, and Anopheles species

B.malayi is transmitted by Anopheles and Mansonia species.

Anopheles

Aedes

CulexMansonia

Geographic Range Lymphatic filariasis occurs in the tropics of

India, Africa, Southern Asia, the Pacific, and Central and South America.

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

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.

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

Wuchereria Life Cycle

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.

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

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

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.

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.

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

…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

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

Elimination programs

Finally… http://youtube.com/watch?v=SkIryQ6Paqg