wuchereria bancrofti

Wuchereria bancroftiPrepared by: Ron Louise B. Salomon

TAXONOMY

• Domain: Eukaryota• Kingdom: Metazoa• Phylum: Nematoda• Class: Secernentea• Order: Spirurida• Family: Filariidae• Genus: Wuchereria• Species: bancrofti

GEOGRAPHICAL DISTIBUTION

• Lymphatic filariasis affects over 120 million people in 73 countries throughout the tropics and sub-tropics of Asia, Africa, the Western Pacific, and parts of the Caribbean and South America.

GEOGRAPHICAL DISTIBUTION

• In the Americas, only four countries are currently known to be endemic: Haiti, the Dominican Republic, Guyana and Brazil.

• In the United States, Charleston, South Carolina, was the last known place with lymphatic filariasis. The infection disappeared early in the 20th century. Currently, you cannot get infected in the U.S.

GEOGRAPHICAL DISTRIBUTION

• In the Philippines, it can be found in:

1. Camarines Norte, Sur

2. Albay, Sorsogon, Mindoro, Masbate, Romblon, Marinduque

3. Bohol, Samar, Leyte, Palawan

4. Mountain Provinces

5. All provinces of Mindanao

MORPHOLOGY OF STAGES

A. MICROFILARIA

The embryo itself averages 290 μm by 6-7 μm, though the sheath surrounding it is slightly larger. The cuticle of the embryo has well-marked striations and the tail tapers gradually to a rounded tip.

MORPHOLOGY OF STAGES

MORPHOLOGY OF STAGES

• B. INFECTIVE (3RD STAGE) LARVAThe head of the infective larva is truncate-conic,

trapezoidal when viewed laterally. The oral aperture is circular with prominent papillae ringing the outer edge. The tail is blunt with three caudal papillae, two latero-ventral and one dorso-terminal. In females the tail is relatively longer. As the larva grows the head loses its truncate shape and is well rounded by the time it develops into a 4th stage larva.

MORPHOLOGY OF STAGES

MORPHOLOGY OF STAGES

• C. ADULT A translucent white worm with a

smooth cuticle. The head is rounded and separated from the body by a neck-like constriction. In females the tail tapers gradually and is rounded at the tip, while in males the tail curves ventrally. Males and females live coiled together. Females vary in length from 30-100 mm with a diameter ranging from 100-300 μm. Males are smaller, typically half the size of females.

LIFE CYCLE

DISEASES AND SYMPTOMS

Lymphatic Filariasis

is a parasitic disease caused by microscopic, thread-like worms. The adult worms only live in the human lymph system. The lymph system maintains the body's fluid balance and fights infections.

DISEASES AND SYMPTOMS

• The disease spreads from person to person by mosquito bites. When a mosquito bites a person who has lymphatic filariasis, microscopic worms circulating in the person's blood enter and infect the mosquito. People get lymphatic filariasis from the bite of an infected mosquito. The microscopic worms pass from the mosquito through the skin, and travel to the lymph vessels. In the lymph vessels they grow into adults. An adult worm lives for about 5–7 years. The adult worms mate and release millions of microscopic worms, called microfilariae, into the blood. People with the worms in their blood can give the infection to others through mosquitoes.

DISEASES AND SYMPTOMS

• Although the parasite damages the lymph system, most infected people have no symptoms and will never develop clinical symptoms. These people do not know they have lymphatic filariasis unless tested.

DISEASES AND SYMPTOMS

• • A small percentage of persons will develop lymphedema. This is caused by fluid collection because of improper functioning of the lymph system resulting in swelling. This mostly affects the legs, but can also occur in the arms, breasts, and genitalia. Most people develop these symptoms years after being infected.

DISEASES AND SYMPTOMS

ElephantiasisThe swelling and the decreased

function of the lymph system make it difficult for the body to fight germs and infections. These people will have more bacterial infections in the skin and lymph system. This causes hardening and thickening of the skin, which is called elephantiasis. Many of these bacterial infections can be prevented with appropriate skin hygiene and exercise.

DISEASES AND SYMPTOMS

DISEASES AND SYMPTOMS

Hydrocele/ Scrotal Swelling

DISEASES AND SYMPTOMS

Kidney Damage

This will lead to blood and protein loss in urine (hematuria).

DISEASES AND SYMPTOMS

Tropical Pulmonary Eosinophilia Syndrome

This syndrome is typically found in persons living with the disease in Asia. Symptoms of tropical pulmonary eosinophilia syndrome include cough, shortness of breath, and wheezing. The eosinophilia is often accompanied by high levels of IgE (Immunoglobulin E) and antifilarial antibodies.

DIAGNOSIS

1. Night Blood Sampling 1.1. Collect blood specimen from 8 pm to 4 am –

Thick Smear (Giemsa or H&E) 1.2. Microscopic examination for microfilariae 1.3. Concentration Technique (increased

sensitivity)

2. Antigen-detection (ELISA) to detect CFA (circulating filarial antigen)

“Gold Standard”

DIAGNOSIS

3. Search for microfilaria in chylous urine, lymph exudates and hydrocoele fluid.

4. Search for adult worm 4.1. Lymph node biopsy 4.2. X-Ray (calcified worm) 4.3. Ultrasonography (dancing worm/filarial dance sign)

5. Xenodiagnosis -mosquito stomach blood, not very helpful

TREATMENT

• Antifilarial Drugs

a. Diethylcarbamazine (DEC)

Dosage: 6 mg/kg/day for 12 days

b. Ivermectin

Dosage: single oral dose of 150 ug/kg body weight

c. Combination of 2 =better results

TREATMENT

General Measures:

1. Rest

2. Antibiotics

3. Antifungal

4. Physiotherapy

5. Bandaging

Elephantiasis

Elephantoid tissues can be corrected surgically.

PREVENTION AND CONTROL

Avoiding mosquito bites is the best form of prevention. The mosquitoes that carry the microscopic worms usually bite between the hours of dusk and dawn. If you live in or travel to an area with lymphatic filariasis:

1. Sleep under a mosquito net.2. Wear long sleeves and trousers.3. Use mosquito repellent on exposed skin between dusk

and dawn.

PREVENTION AND CONTROL

Even after the adult worms die, lymphedema can develop. You can ask your physician for a referral to see a lymphedema therapist for specialized care. Prevent the lymphedema from getting worse by following several basic principles:

1. Carefully wash the swollen area with soap and water every day.

2. Elevate and exercise the swollen arm or leg to move the fluid and improve the lymph flow.

3. Disinfect any wounds. Use antibacterial or antifungal cream if necessary.

LINKS TO SOURCES

• http://bioweb.uwlax.edu/bio203/s2008/krout_bria/phylogenetictree.htm

• http://www.cdc.gov/parasites/lymphaticfilariasis/epi.html

• https://uqu.edu.sa/files2/tiny_mce/plugins/filemanager/files/4320483/Blood__Tissue_Nematodes.pdf

THE END