Megan Larson and Michelle Stanek

Wuchereria bancrofti

W. Bancrofti causes lymphatic filariasis

This is also known as elephantiasis

It affects over 120 million people worldwidehttp://www.youtube.com/watch?v=dnWwHthkGkY&feature=related

http://animal.discovery.com/videos/monsters-inside-me-lymphatic-filariasis.html

Background

Definitive Host: HumansIntermediate Host: Mosquitoes (especially night-

feeding mosquitoes) Species: Anopheles, Aedes, Culex, Mansonia

Morphology:Males:

40 mm long & 100 μm wideFingerlike tail

Females:6-10 cm long & 300 μm wideThey are viviparous Their vulva is near the level of the middle of their esophagus

Wuchereria bancrofti

Sub-Saharan AfricaEgyptSouthern AsiaWestern Pacific

islandsNortheastern coast of

BrazilGuyanaCaribbean island of

Hispaniola

Geographic Distribution

Life Cycle

1. 1.The mosquito takes a blood meal, transferring the L3 larva into the skin.

2. The L3 larva grow into adults in the lymph ducts. 3. The adults reproduce, producing sheathed microfilariae;

the microfilariae migrate into the blood and lymph channels

4. A mosquito takes a blood meal, ingesting the microfilariae.5. Once in the mosquito, the sheath of the microfilariae is

sloughed off. The microfilariae then penetrates the midgut of the mosquito, making its way into the thoracic muscles.

6. L1 larvae form7. L3 larvae form8. The L3 larvae are the infective stage, traveling to the

mosquito’s head and proboscis.

Life Cycle Continued

Microfilaria are present in the peripheral blood at certain times of the day

During the night (10 p.m.-2 a.m.) Maximum number of microfilaria present in the peripheral blood

During the day Microfilaria are concentrated in blood vessels of deep tissues of

the body (pulmonary capillaries, ect…)

Periodicity

6-12 months must pass before the microfilariae mature and reproduce

Once a person is infected, microfilariae can be produced for up to ten years.

There are 3 phases of infections: asymptomatic, inflammatory (acute), and obstructive.

Pathogenesis

Asymptomatic Phase: High levels of microfilaria in the blood No symptoms present

Inflammatory (Acute) Phase: Inflammatory responses happen in response to antigens from

adult worms Lymphedema—swelling due to blockage of lymph vessels Orchitis—inflammation of the testes Epididymitis—inflammation of the spermatic cord

Obstructive Phase: Lymph varices—enlarged lymph vessels (synonymous with

varicose veins) Lymph scrotum Chyluria—lymph in urine (milky and sometimes bloody urine) Elephantiasis—enlargement of limbs and thickening of the skin

due to repeated inflammatory episodes

Pathogenesis Continued…

Wuchereria bancrofti

Elephantiasis

Lymphedema

Orchitis

Chyluria

Thick blood smear Juveniles must be present in

peripheral blood

Polymerase chain reaction (PCR) Distinguishes between other

similar species

Ultrasonography Detects vigorous movement of

adults known as “filaria dance sign”

X-rays Detects dead, calcified worms

Diagnosis

Primary drug of choice: diethylcarbamazine (DEC)Eliminates microfilaria from

the blood and (if administered correctly) kills adult worms

Ivermectin

Albendazole & Mectizan

Application of pressure bandages

Treatment

Administration of Albendazole & Mectizan to control the spread of the disease.

There are currently no vaccines Elimination of common mosquito

breeding grounds Fallen coconuts Any small container filled with water

They hope to eradicate it by year 2020; so far, the diseased population has declined significantly

http://www.youtube.com/watch?v=dnWwHthkGkY&feature=related

Control

CDC. http://www.cdc.gov/parasites/lymphaticfilariasis/biology_w_bancrofti.html

Guyen Et. al. “Evidence for Wolbachia symbiosis in microfilariae of Wuchereria bancrofti from West Bengal, India.” <http://www.ias.ac.in/jbiosci/gayen150.pdf>.

Schmidt, GD; Roberts, LS. Foundations of Parasitology. Seventh ed. P. 461-66.

http://www.youtube.com/watch?v=dnWwHthkGkY&feature=related

http://animal.discovery.com/videos/monsters-inside-me-lymphatic-filariasis.html

Sources

Questions?

What is the definitive host?

What is the intermediate host?

What is the infective stage of this parasite?

What stage is this parasite transmitted to the mosquito?

What part of the body does this parasite infect?

What is a major side effect of this parasite?

Quiz