Lymphatic filariasis
Alternate names[edit | edit source]
Filariasis; Elephantiasis; Wuchereria Bancrofti infection; Filarial elephantiasis; Malayi tropical eosinphilia; Wuchereriasis; Bancroftian filariasis; Elephantitis
Definition[edit | edit source]
Lymphatic filariasis is a parasitic disease caused by microscopic, thread-like worms that only live in the human lymph system, which maintains the body's fluid balance and fights infections. Lymphatic filariasis, considered globally as a neglected tropical disease (NTD).
Cause[edit | edit source]
The causative agents of lymphatic filariasis (LF) include the mosquito-borne filarial nematodes Wuchereria bancrofti, Brugia malayi, B. timori An estimated 90% of LF cases are caused by W. bancrofti (Bancroftian filariasis).
Epidemiology[edit | edit source]
Lymphatic filariasis affects over 120 million people in 72 countries throughout the tropics and sub-tropics of Asia, Africa, the Western Pacific, and parts of the Caribbean and South America. You cannot get infected with the worms in the United States.
Spread[edit | edit source]
- 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.
- When the infected mosquito bites another person, 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.
Risk factors[edit | edit source]
- Repeated mosquito bites over several months to years are needed to get lymphatic filariasis.
- People living for a long time in tropical or sub-tropical areas where the disease is common are at the greatest risk for infection.
- Short-term tourists have a very low risk.
- An infection will show up on a blood test.
Signs and symptoms[edit | edit source]
Most infected people are asymptomatic and never develop clinical symptoms. A small percentage of people develop lymphedema, which may affect the legs, arms, breasts, and genitalia; bacterial infections that cause hardening and thickening of the skin, called elephantiasis; hydrocele (swelling of the scrotum) in men; and pulmonary tropical eosinophilia syndrome.
Clinical presentation[edit | edit source]
For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms
- Lymphadenopathy(Swollen lymph nodes)
- Predominantly lower limb lymphedema
30%-79% of people have these symptoms
- Circulating immune complexes
- Fatigue(Tired)
- Hypereosinophilia
- Hyperkeratosis
- Hyperpigmentation of the skin(Patchy darkened skin)
- Lymphadenitis(Inflammation of the lymph nodes)
- Pain
5%-29% of people have these symptoms
- Abnormal lung morphology(Abnormality of lung structure)
- Cough(Coughing)
- Fever
- Hydrocele testis
- Lymphangiectasis
- Opportunistic bacterial infection
- Orchitis(Inflammation of testicles)
- Restrictive ventilatory defect(Stiff lung or chest wall causing decreased lung volume)
- Vaginal hydrocele
- Wheezing
1%-4% of people have these symptoms
- Ankle swelling
- Epididymitis
- Glomerulonephritis
- Hematuria(Blood in urine)
- Knee osteoarthritis
- Nephrotic syndrome
- No social interaction
- Proteinuria(High urine protein levels)
- Urethral obstruction
Diagnosis[edit | edit source]
- The standard method for diagnosing active infection is the examination of blood under the microscope to identify the microscopic worms, called microfilariae.
- This is not always feasible because in most parts of the world, microfilariae are nocturnally periodic, which means that they only circulate in the blood at night.
- For this reason, the blood collection has to be done at night to coincide with the appearance of the microfilariae in the blood.
- Serologic techniques provide an alternative to microscopic detection of microfilariae for the diagnosis of lymphatic filariasis.
- Because lymphedema may develop many years after infection, lab tests are often negative with these patients.
Treatment[edit | edit source]
- People infected with adult worms can take a yearly dose of medicine, called diethylcarbamazine (DEC), that kills the microscopic worms circulating in the blood.
- While this drug does not kill all of the adult worms, it does prevent infected people from giving the disease to someone else.
- People with lymphedema and elephantiasis are not likely to benefit from DEC treatment because most people with lymphedema are not actively infected with the filarial parasite.
- Physicians can obtain DEC from CDC after lab results confirm infection.
- People with lymphedema and hydrocele can benefit from lymphedema management, and in the case of hydrocele surgical repair.
- 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:
- Carefully wash and dry the swollen area with soap and water every day.
- Elevate the swollen arm or leg during the day and at night to move the fluid.
- Perform exercises to move the fluid and improve lymph flow.
- Disinfect any wounds. Use antibacterial or antifungal cream if necessary.
- Wear shoes adapted to the size of the foot to protect the feet from injury.
- Men with hydrocele can undergo surgery to reduce the size of the scrotum.
Prevention[edit | edit source]
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:
- Sleep under a mosquito net.
- Wear long sleeves and trousers.
- Use mosquito repellent on exposed skin between dusk and dawn.
NIH genetic and rare disease info[edit source]
Lymphatic filariasis is a rare disease.
Lymphatic filariasis Resources | ||
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