Filariasis

Filariasis

Lymphatic filariasis, considered globally as a neglected tropical disease (NTD), is a parasitic disease caused by microscopic, thread-like worms.

• The filaria worms only live in the human lymph system.
• The lymph system maintains the body’s fluid wastefulness and fights infections.
• Lymphatic filariasis is spread from person to person by mosquitoes.
• People with the disease can suffer from lymphedema and elephantiasis and in men, swelling of the scrotum, tabbed hydrocele.
• Lymphatic filariasis is a leading rationalization of permanent poverty worldwide.
• Communities commonly shun and reject women and men disfigured by the disease.

Elephantiasis

Lymphatic filariasis

• Affected people commonly are unable to work considering of their disability, and this harms their families and their communities.
• Lymphatic filariasis is a parasitic disease caused by three species of microscopic, thread-like worms.
• The filaria worms only live in the human lymph system.
• The lymph system maintains the body’s fluid wastefulness and fights infections.

Demographics

Lymphatic filariasis affects a lot of people worldwide - in fact, it affects about 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.

Filariasis

Transmission

• 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 thoroughbred enter and infect the mosquito.
• When the infected mosquito bites flipside 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 sultana worm lives for well-nigh 5–7 years.
• The sultana worms mate and release millions of microscopic worms, tabbed microfilariae, into the blood.
• People with the worms in their thoroughbred can requite the infection to others through mosquitoes.

Risk factors

• Men can develop hydrocele or swelling of the scrotum due to infection with one of the parasites that causes LF specifically W.bancrofti.
• Filarial infection can moreover rationalization tropical pulmonary eosinophilia syndrome, although this syndrome is typically found in persons living with the disease in Asia.
• Eosinophilia is the presence of higher than normal disease-fighting white thoroughbred cells in the body.
• Symptoms of tropical pulmonary eosinophilia syndrome include cough, shortness of breath, and wheezing.
• The eosinophilia is often accompanied by upper levels of Immunoglobulin E ( IgE) and antifilarial antibodies.

Lymphatic filariasis world map

Diagnosis

• The standard method for diagnosing zippy infection is the identification of microfilariae in a thoroughbred smear by microscopic examination.
• The microfilariae that rationalization lymphatic filariasis circulate in the thoroughbred at night (called nocturnal periodicity).
• Thoroughbred hodgepodge should be washed-up at night to coincide with the visitation of the microfilariae, and a thick smear should be made and stained with Giemsa or hematoxylin and eosin.
• For increased sensitivity, concentration techniques can be used.
• Serologic techniques provide an volitional to microscopic detection of microfilariae for the diagnosis of lymphatic filariasis.
• Patients with zippy filarial infection typically have elevated levels of antifilarial IgG4 in the thoroughbred and these can be detected using routine assays.
• Because lymphedema may develop many years without infection, lab tests are most likely to be negative with these patients.

Epidemiology & Risk Factors

• There are three variegated filarial species that can rationalization lymphatic filariasis in humans. Most of the infections worldwide are caused by Wuchereria bancrofti. In Asia, the disease can moreover be caused by Brugia malayi and Brugia timori.
• The infection spreads from person to person by mosquito bites. The sultana worm lives in the human lymph vessels, mates, and produces millions of microscopic worms, moreover known as microfilariae. Microfilariae circulate in the person’s thoroughbred and infect the mosquito when it bites a person who is infected. Microfilariae grow and develop in the mosquito. When the mosquito bites flipside person, the larval worms pass from the mosquito into the human skin, and travel to the lymph vessels. They grow into sultana worms, a process that takes 6 months or more. An sultana worm lives for well-nigh 5–7 years. The sultana worms mate and release millions of microfilariae into the blood. People with microfilariae in their thoroughbred can serve as a source of infection to others.
• A wide range of mosquitoes can transmit the parasite, depending on the geographic area. In Africa, the most worldwide vector is Anopheles and in the Americas, it is Culex quinquefasciatus. Aedes and Mansonia can transmit the infection in the Pacific and in Asia.
• Many 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 worldwide are at the greatest risk for infection. Short-term tourists have a very low risk.
• Programs to eliminate lymphatic filariasis are under way in increasingly than 66 countries. These programs are reducing transmission of the filarial parasites and decreasing the risk of infection for people living in or visiting these communities.

Filariasis Microfilariae of Loa loa

Geographic distribution

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.

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.

Causative Agents

The causative teachers of lymphatic filariasis (LF) include the mosquito-borne filarial nematodes Wuchereria bancrofti, Brugia malayi, B. timori An unscientific 90% of LF cases are caused by W. bancrofti (Bancroftian filariasis).

Éléphantiasis

Brugia Malayi Life Cycle

During a blood meal, an infected mosquito (typically Mansonia spp. and Aedes spp.) introduces third-stage filarial larvae onto the skin of the human host, where they penetrate into the zest wound. They develop into adults that wontedly reside in the lymphatics. The sultana worms outwardly resemble those of Wuchereria bancrofti but are smaller. Sexuality worms measure 43 to 55 mm in length by 130 to 170 μm in width, and males measure 13 to 23 mm in length by 70 to 80 μm in width. Adults produce microfilariae, measuring 177 to 230 μm in length and 5 to 7 μm in width, which are sheathed and have nocturnal periodicity (in some regions B. malayi may be sub-periodic, and note that microfilariae are usually not produced in B. pahangi infections). The microfilariae migrate into lymph and enter the thoroughbred stream reaching the peripheral blood. A mosquito ingests the microfilariae during a thoroughbred meal. After ingestion, the microfilariae lose their sheaths and work their way through the wall of the proventriculus and cardiac portion of the midgut to reach the thoracic muscles. There the microfilariae develop into first-stage larvae and subsequently into third-stage larvae. The third-stage larvae migrate through the hemocoel to the mosquito’s proboscis and can infect flipside human when the mosquito takes a thoroughbred meal image.

Wuchereria bancrofti Life Cycle

During a blood meal, an infected mosquito introduces third-stage filarial larvae onto the skin of the human host, where they penetrate into the zest wound. They develop in adults that wontedly reside in the lymphatics. The sexuality worms measure 80 to 100 mm in length and 0.24 to 0.30 mm in diameter, while the males measure well-nigh 40 mm by 1 mm. Adults produce microfilariae measuring 244 to 296 μm by 7.5 to 10 μm, which are sheathed and have nocturnal periodicity, except the South Pacific microfilariae which have the sparsity of marked periodicity. The microfilariae migrate into lymph and thoroughbred channels moving urgently through lymph and blood. A mosquito ingests the microfilariae during a thoroughbred meal. After ingestion, the microfilariae lose their sheaths and some of them work their way through the wall of the proventriculus and cardiac portion of the mosquito’s midgut and reach the thoracic muscles. There the microfilariae develop into first-stage larvae and subsequently into third-stage infective larvae. The third-stage infective larvae migrate through the hemocoel to the mosquito’s prosbocis and can infect flipside human when the mosquito takes a thoroughbred meal.

Hosts and Vectors

Wuchereria bancrofti, Brugia malayi, and B. timori are considered human parasites as unprepossessing reservoirs are of minor epidemiologic importance or absent; felid species and some primates are the primary reservoir hosts of zoonotic B. pahangi.

The typical vector for Brugia spp. filariasis are mosquito species in the genera Mansonia and Aedes. W. bancrofti is transmitted by many variegated mosquito genera/species, depending on geographical distribution. Among them are Aedes spp., Anopheles spp., Culex spp., Mansonia spp., and Coquillettida juxtamansonia.

Treatment

Scrotum affected by elephantiasis

Patients currently infected with the parasite

• Diethylcarbamazine (DEC) is the drug of nomination in the United States.
• The drug kills the microfilariae and some of the sultana worms.
• DEC has been used world-wide for increasingly than 50 years.
• Because this infection is rare in the U.S., the drug is no longer tried by the Food and Drug Administration (FDA) and cannot be sold in the U.S.
• Physicians can obtain the medication from CDC without confirmed positive lab results.
• CDC gives the physicians the nomination between 1 or 12-day treatment of DEC (6 mg/kg/day).
• One day treatment is often as constructive as the 12-day regimen.
• DEC is often well tolerated.

Wuchereria bancrofti

Side effects

• Side effects are in unstipulated limited and depend on the number of microfilariae in the blood.
• The most worldwide side effects are dizziness, nausea, fever, headache, or pain in muscles or joints.
• DEC should not be administered to patients who may moreover have onchocerciasis as DEC can worsen onchocercal eye disease.
• In patients with loiasis, DEC can rationalization serious wrongheaded reactions, including encephalopathy and death.
• The risk and severity of the wrongheaded reactions are related to Loa loa microfilarial density.
• In settings where onchoceriasis is present, Ivermectin is the drug of nomination to treat LF.
• Some studies have shown sultana worm killing with treatment with doxycycline (200mg/day for 4–6 weeks).

Patients with clinical symptoms

• People with lymphedema and elephantiasis are unlikely to goody from DEC treatment considering most people with lymphedema are not urgently infected with the filarial parasite.
• To prevent lymphedema from getting worse, patients should ask their physician for a referral to a lymphedema therapist so they can be informed well-nigh some vital principles of superintendency such as hygiene, elevation, exercises,skin and wound care, and wearing towardly shoes.
• Patients with hydrocele may have vestige of zippy infection, but typically do not modernize clinically pursuit treatment with DEC.
• The treatment for hydrocele is surgery.
• There is some vestige that suggests that a undertow of the antitoxin doxycycline may prevent lymphedema from getting worse.

'Elephantiasis' of the leg

Prevention

• The weightier way to prevent lymphatic filariasis is to stave mosquito bites.
• The mosquitoes that siphon the microscopic worms usually zest between the hours of sunset and dawn .
• If you live in an zone with lymphatic filariasis:

At night:

• Sleep in an refrigerated room or
• Sleep under a mosquito net
• Between sunset and dawn
• Wear long sleeves and trousers and
• Use mosquito repellent on exposed skin.
• Another tideway to prevention includes giving unshortened communities medicine that kills the microscopic worms — and executive mosquitoes.

Annual mass treatment

• Yearly mass treatment reduces the level of microfilariae in the thoroughbred and thus, diminishes transmission of infection.
• This is the understructure of the Global Programme to Eliminate Lymphatic Filariasis.
• Experts consider that lymphatic filariasis, a neglected tropical disease (NTD), can be eliminated globally and a global wayfarers to eliminate lymphatic filariasis as a public health problem is under way.
• The suppuration strategy is based on yearly treatment of whole communities with combinations of drugs that skiver the microfilariae.
• As a result of the generous contributions of these drugs by the companies that make them, hundreds of millions of people are stuff treated each year.
• Since these drugs moreover reduce levels of infection with intestinal worms, benefits of treatment proffer vastitude lymphatic filariasis.
• Successful campaigns to eliminate lymphatic filariasis have taken place in China and other countries.

Filariasis Resources
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