Lymphatic Filariasis / Elephantiasis

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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
Anopheles

• W.bancrofti is transmitted by Culex, Aedes, and
  Anopheles species
• B.malayi is transmitted by Anopheles and Mansonia
  species.

Aedes
Culex
Mansonia
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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?vSkIryQ6Paqg