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Filariasis

Filariases

Filariasis is a parasitic disease caused by tissue nematodes.


Presentation

Lymphatic filariasis can be asymptomatic, where infected people have no symptoms and never will develop symptoms. Other people that are infected will present with acute clinical symptoms [3].

Acute symptoms of the disease include:

  • Adenolymphangitis (ADL) – this presents with sudden onset of fever and painful lymphadenopathy. ADL may occur due to immune mediated responses to dying adult worms. Many anatomic sites may be involved: the inguinal lymph nodes and lower extremities, genetalia (scrotum) are common sites.
  • Filarial fevers – Filarial fever consist of self-limited cyclical episodes of high fever. In tropical settings, these fevers may be confused with other causes of fever in tropics such as malaria.
  • Tropical pulmonary eosinophilia – This is caused by an immune hyper responsiveness to the microfilariae trapped in the lungs. It is characterized by wheezing at night. The “classic” presentation is: cough, fever, marked high eosinophilia count, high serum immunoglobulin E concentrations and positive antifilarial antibodies. Eosinophilia may exceed 3000/microL, although infections with other parasites may also result in such high eosinophilia levels.

In travelers (those that do not live in the endemic areas) – the exposure is usually insufficient to filariasis to develop chronic complications. However, these persons may manifest hypersensitivity reactions to the developing larvae: eosoinophilic infiltrate with lymphangitis and lymphadenitis, urticarial and rash.

Chronic symptoms include [4]:

  • Renal Involvement – Intestinal lymph may be discharged to the renal pelvis, causing lymphatic fluid to be passed in the urine (known as chyluria). It has a milky appearance to urine. Cyluria may affect an individual’s nutritional status and therefore should be addressed promptly. Hematuria and/or proteinuria can also occur when there is renal involvement. The exact mechanism for this is unknown.
Fever
  • Diethylcarbamazine shows remarkable effect against filarial fever and hemato-chyluria. Oxophenarsine hydrochloride shows a satisfactory effect on filarial fever.[doi.org]
  • Filarial fevers – Filarial fever consist of self-limited cyclical episodes of high fever. In tropical settings, these fevers may be confused with other causes of fever in tropics such as malaria.[symptoma.com]
  • This report describes a case of filariasis in a child who presented with fever and extensive lower-extremity edema.[ncbi.nlm.nih.gov]
  • Symptoms and Signs The symptoms that occur in persons affected by filariasis are: Fever with chills, Swelling in the area where the adult worms are present Enlargement of the lymph nodes Recurrent episodes of fever with chills can occur Inflammatory changes[webhealthcentre.com]
  • ‘Malaria, filariasis, and dengue fever are the three major causes of morbidity and mortality in developing countries.’ Pronunciation filariasis /ˌfɪləˈrʌɪəsɪs/ /fɪˌlɛːrɪˈeɪsɪs[en.oxforddictionaries.com]
Chills
  • General symptoms of filariasis include fever, chills, headache and skin lesions. Further progression of the disease will disfigure the patient with excessive swelling of the limbs.[byjus.com]
  • Symptoms and Signs The symptoms that occur in persons affected by filariasis are: Fever with chills, Swelling in the area where the adult worms are present Enlargement of the lymph nodes Recurrent episodes of fever with chills can occur Inflammatory changes[webhealthcentre.com]
  • Filariasis is characterized by fever, chills, headache, and skin lesions in the early stages and, if untreated, can progress to include gross enlargement of the limbs and genitalia in a condition called elephantiasis.[encyclopedia.com]
  • Other affected individuals may have episodes of acute inflammation of lymphatic vessels (lymphangitis) along with high temperatures, shaking chills, body aches, and swollen lymph nodes.[rarediseases.org]
Lymphedema of the Lower Extremity
  • Chronic pitting lymphedema of a lower extremity can progress to elephantiasis (chronic lymphatic obstruction). W. bancrofti can cause hydrocele and scrotal elephantiasis.[merckmanuals.com]
Abdominal Pain
  • Serous cavity filariasis may cause similar symptoms to those seen in the subcutaneous form, along with abdominal pain. A diagnosis of this condition is usually confirmed when a blood film shows the presence of microfilariae.[news-medical.net]
  • Abdominal pain Damage to the cornea, choroid, retina and optic nerve finally resulting in loss of vision. The hyper or hypopigmented skin on the face, arms, feet, and other parts of the body.[byjus.com]
  • Serous cavity filariasis presents with symptoms similar to subcutaneous filariasis, in addition to abdominal pain, because these worms are also deep-tissue dwellers.[en.wikipedia.org]
  • Symptoms include swelling of the arms, shoulders, and face; abdominal pain; itchiness; fatigue; and joint pain.[dermnetnz.org]
  • Symptoms caused by the death of the parasites include fever, headache, muscle pain, abdominal pain, nausea and vomiting, weakness, dizziness, lethargy, and asthma.[encyclopedia.com]
Arthralgia
  • Diethylcarbamazine has common but limited side effects, including headaches, asthenia, arthralgia, anorexia, nausea and vomiting. Patients must be warned against the risk of somnolence after taking the product.[therapeutique-dermatologique.org]
Pruritus
  • 125.9 filariensis (see also Infestation, filarial) 125.9 Filariasis (see also Infestation, filarial) 125.9 due to Hematochyluria (see also Infestation, filarial) 125.9 Hydrothorax (double) (pleural) 511.89 Infestation 134.9 filarial 125.9 Itch (see also Pruritus[icd9data.com]
  • Doxycycline treatment may be particularly beneficial for people with onchodermatitis and pruritus who would otherwise require repeated treatment with ivermectin over a period of years.[emedicine.medscape.com]
  • These reactions may present as an exacerbation of the local lymphatic signs or general symptoms arising a few hours after the first intake, for instance, fever, headaches, diffuse pain, pruritus and urticaria.[therapeutique-dermatologique.org]
Withdrawn
  • A 42 year old male individual having a hugely distended scrotum and barely perceptible penis, unable to maintain his livelihood on account of his handicap and socially withdrawn for the fear of humiliation, got admitted into the Surgery department of[ncbi.nlm.nih.gov]
Swelling of the Scrotum
  • People with the disease can suffer from lymphedema and elephantiasis and in men, swelling of the scrotum, called hydrocele. Lymphatic filariasis is a leading cause of permanent disability worldwide.[cdc.gov]
  • In men, elephantiasis can also result in the swelling of the scrotum (hydrocele). Elephantiasis affects the poorest communities, preventing individuals from living a productive working and social life, further trapping them in the cycle of poverty.[unitingtocombatntds.org]
  • In men, lymphedema of the genitalia usually involves swelling of the scrotum, often to the size of a watermelon making it very painful and difficult to walk. In women, the condition may present swelling in one or both breasts.[end.org]
Testicular Pain
  • Furthermore, there can be testicular pain during the type 2 reaction in Hansen's disease. Filariasis is a disease caused by the parasitic nematode, Wuchereria bancrofti.[ncbi.nlm.nih.gov]
Scrotal Pain
  • In some cases, acute scrotal pain may lead to the suspicion of testicular torsion.[ncbi.nlm.nih.gov]

Workup

Diagnosis can be made with a blood smear. The microfilariae that cause lymphatic filariasis circulate in the blood at night; therefore blood draw should be performed at night. The smear is stained with Giemsa or hematoxylin and eosin and microscopically evaluated for the worm.

Blood tests that detect antigens for the parasites are also available as a diagnostic tool. Circulating antigen detection assay (CFA assay) has been developed for diagnosis of W. bancrofti infections. This test detect antigens released by adult worms, in addition to microfilariae, and therefore can be performed at any time of the day.

There are two commercially CFA tests available for detection of W. bancrofti: Og4C3 ELISA assay which gives an actual count (quantative measure) of adult worms in the body; and TropBio ELISA test that gives only a positive or negative (qualitative) result [5].

Imaging: Ultrasound can be used to detect presence of adult worms in lymphatic vessels. A scan that is positive for the disease shows as a “filarial dance sign” indicating movements of the worms in blood [6].

Pericardial Effusion
  • Though relatively uncommon, tropical diseases must always be considered in the etiological diagnosis of pericardial effusion.[ncbi.nlm.nih.gov]
Wuchereria Bancrofti
  • Elephantiasis due to Wuchereria bancrofti Infection due to Wuchereria bancrofti Lymphadenitis due to Wuchereria bancrofti Lymphangitis due to Wuchereria bancrofti Wuchereriasis ICD-9-CM Volume 2 Index entries containing back-references to 125.0 :[icd9data.com]
  • Pleural fluid on examination was exdudative in nature and showed presence of microfilariae of Wuchereria bancrofti.[ncbi.nlm.nih.gov]
  • In India, filariasis is predominantly caused by a species of nematode called Wuchereria bancrofti. The disease is transmitted through the bite of blood sucking mosquitoes.[ncbi.nlm.nih.gov]
  • bancrofti , Brugia malayi , and Brugia timori , all transmitted by mosquitoes.[commons.wikimedia.org]
  • Da Wikimedia Commons, l'archivio di file multimediali liberi Jump to navigation Jump to search Lymphatic Filariasis is a parasitic and infectious tropical disease, caused by the thread-like parasitic filarial worms, Wuchereria bancrofti , Brugia malayi[commons.wikimedia.org]
Brugia Malayi
  • Six formulations (ALB-1 to ALB-6) were prepared and tested against Brugia malayi in Mastomys coucha and jird ( Meriones unguiculatus ) at 200 mg/kg, orally, for 5 consecutive days.[doi.org]
  • malayi , and Brugia timori , all transmitted by mosquitoes.[commons.wikimedia.org]
  • Da Wikimedia Commons, l'archivio di file multimediali liberi Jump to navigation Jump to search Lymphatic Filariasis is a parasitic and infectious tropical disease, caused by the thread-like parasitic filarial worms, Wuchereria bancrofti , Brugia malayi[commons.wikimedia.org]
  • Wuchereria bancrofti, Brugia malayi, and Brugia timori, categorized as nematodes, are responsible for causing lymphatic filariasis.[ncbi.nlm.nih.gov]
  • Lymphatic filariasis is caused by the filarial nematodes Wuchereria bancrofti, Brugia malayi, and Brugia timori. Lymphatic filariasis is common in tropical and subtropical regions.[ncbi.nlm.nih.gov]
Acanthocheilonema Perstans
  • Other forms of filariasis are caused by Acanthocheilonema perstans and Mansonella ozzardi and are not in most cases associated with specific symptoms. The prevention of filariasis relies heavily on insecticides and insect repellents.[britannica.com]
Tissue Nematode
  • Filariasis is a parasitic disease caused by tissue nematodes. Lymphatic filariasis can be asymptomatic, where infected people have no symptoms and never will develop symptoms. Other people that are infected will present with acute clinical symptoms.[symptoma.com]

Treatment

Medications

Persons currently infected with the parasite are treated with diethylcarbamazine (DEC) 6 mg/kg for 12 days irrespective of clinical symptoms [7]. DEC kills the adult worms and therefore ultimately decreases the microfilarial burden. DEC should be avoided in pregnancy and lactation [8].

Doxycycline is sometimes given in addition to DEC (200 mg/d for 4 to 6 weeks) as it has demonstrated macro filaricidal activity and reduces pathology in mild and moderate diseases [9].

DEC is contraindicated in patients as it can worsen onchocercal eye disease. In patients with loiasis, DEC can cause serious adverse reactions such as encephalopathy and death. In such patients doxycycline should be used [10].

Treatment of symptoms (while being treated medically, with DEC or doxycycline) include: lymphedema and acute inflammatory episodes can be relieved using hygiene care, skin care, exercise and most importantly, elevation of the limb affected. Surgery can provide relief from hydrocele.

Prognosis

  • Early cases have a good prognosis if properly treated. Cases identified in the late stages have a poor prognosis. Prevention Avoidance of mosquito bites by use of mosquito nets or repellents.[webhealthcentre.com]
  • Treatment and prognosis Treatment options include diethylcarbamazine (DEC) 6mg/kg body weight in combination with albendazole. Complications Grossly dilated lymphatics and edema progressing to elephantiasis .[radiopaedia.org]
  • In such cases, the prognosis is good.[dovemed.com]
  • Prognosis The outlook is good in early or mild cases, especially if the patient can avoid being infected again. The disease is rarely fatal, and with continued WHO medical intervention, even gross elephantiasis is now becoming rare.[encyclopedia.com]

Etiology

The life cycle of the filariasis starts with introduction of larvae injected into human skin by a mosquito bite. The larvae migrate through the mosquito bite wound and enter local lymphatic vessels.

Over nine months, the larvae develop into mature adult worms. The adults male and female worms mate and produce sheathed microfilariae. The microfilariae migrate into lymph and enter the blood stream. When a mosquito bites an infected individual, it ingests the microfilariae and transmits to another human when it bites him/her.

Epidemiology

There are three different filarial species that can cause lymphatic filariasis in humans:

  • Wuchereria bancrofti (W. bancrofti) – only affects humans
  • Brugia malayi (B. malayi) – affects both humans and animals
  • Brugia tmori (B. tmori) – affects both humans and animals

Geographic distribution: Most of the infections in the world are caused by the species: Wuchereria bancrofti. Brugia malayi and Brugia tmori are seen primarily in Asia. It is estimated that more than 120 million people worldwide, in 73 countries are infected.

More than 90% of the infections are caused by W. bancrofti species. In the United States (US), Charleston South Carolina was the last known place with lymphatic filariasis episode. The infection has been eradicated in the US [1].

Age: Lymphatic filariasis is most likely first acquired in childhood, but a third of children remain asymptomatic until 5 years of age. The prevalence of this disease in endemic communities increases with age. In endemic areas, most people have been exposed by 40 years of age.

Sex distribution
Age distribution

Pathophysiology

The pathogenesis of the disease is impacted by several factors such as the extent and duration of exposure to infective insect bites, the quantity of accumulating adult worm antigen in the lymphatic system and the host immune response.

Clinical presentation in exposed persons also depends on a number of host and parasite factors, such as: timing of the first exposure to the parasite, the species of filarial pathogen involved, the intensity of exposure to infected mosquitoes, prenatal sensitization [2]. Genetics may also influence clinical presentation (lymphedema tends to occur in families).

Later in infection, immune responses to parasite antigens are down regulated with suppression of T-lymphocyte proliferation (which results in impaired production of Th1 and Th2, and thus cytokines), therefore contributing to this infection becoming a chronic infection.

Prevention

The best way to prevent filariasis is to avoid mosquito bites.

Summary

Filariasis is a parasitic disease that is caused by nematodes (round worms) that inhibit the lymphatic system and subcutaneous tissues of humans and animals. These are thread-like worms that live in the human lymph system. The infection is transmitted human to human by mosquitos. Lymphatic filariasis is a major cause of disfigurement and disability in endemic areas. For example, people with the disease can have lymphedema and elephantiasis and in men scrotum swelling.

Patient Information

Filariasis is a parasitic disease that is caused by nematodes (round worms). These are thread-like worms that live in the human lymphatic system. Some types of filariasis can be transmitted to both animals and humans by mosquitoes. However the most common type (Wuchereria bancrofti) is transmitted only to humans by mosquitos.

Lymphatic filariasis is a major cause of disfigurement and disability. For example, people with the disease can have lymphedema and elephantiasis and in men scrotum swelling.

Who is at risk?

People who live in tropical and subtropical areas in the world (e.g. Asia, Africa, the Western Pacific, and parts of the Caribbean and South America) are at risk. Most of the infections are caused by the species Wuchereria bancrofti. It is estimated that more than 120 million people worldwide, in 73 countries are infected [11]. W. bancrofti species can only infect humans (unlike the other 2 species which can affect both humans and animals).

There are currently no cases of this disease in the United States.
Both men and women are affected equally. The rate of infection increases with age (in particular during childhood and teenage years).

How is the disease transmitted?

A mosquito bites an infected person and then transmits the disease when it bites another person. When the mosquito bites an infected person, the mosquito becomes infected with microfilariae (larvae, or baby worms).

Then when the mosquito bites another person, the microfilariae are deposited on the skin and enter the human’s body. The microfilariae travel to the lymphatic vessels, where they develop into adult worms. Adult worms mate and produce more microfilariae. The cycle repeats until a person is treated.

What are the symptoms of Filariasis?

Some infected people have no symptoms. They are called “carriers”. The infection can be detected using blood smears (drop of blood is placed on a slide, stained with a special dye and looked at using a microscope).
For those who have symptoms:

  • Acute adeno-lymphangitis (ADL) – symptoms include: painful lymphadenopathy in the groin or axilla (armpits). The areas are painful, tender, red and swollen and can also become infected with bacteria (secondary infection).
  • Acute filarial lymphangitis (AFL) – This is caused by dying adult worms in a human body, either spontaneously or due to treatment. Small tender nodules appear at the site of the worms death. There is NO fever.

What tests can be done to check for the disease?

Blood tests can be performed to check for infection: blood smears, immunological tests that are designed to check for chemicals in your body that are specific to filariasis.

Urinalysis can be performed to check for chyluria and for the microfilariae (under a microscope).
Ultrasound test can also be used to look at certain lympatic areas to detect adult worms.

How can filariasis be treated?

Your doctor can prescribe medications to treat this disease. Common medications used are diethylcarbamazine (DEC) and doxycycline. Symptoms can be alleviated by maintaining good hygiene and keeping the affected body part elevated. A hydrocele can be alleviated by surgery.

References

Article

  1. Budge PJ, Dorkenoo AM, Sodahlon YK, Fasuyi OB, Mathieu E. Ongoing surveillance for lymphatic filariasis in Togo: assessment of alternatives and nationwide reassessment of transmission status. Am J Trop Med Hyg. 2014 Jan;90(1):89-95.
  2. Nutman TB. Insights into the pathogenesis of disease in human lymphatic filariasis. Lymphat Res Biol. 2013 Sep;11(3):144-8.
  3. Keating J, Yukich JO, Mollenkopf S, Tediosi F. Lymphatic filariasis and onchocerciasis prevention, treatment, and control costs across diverse settings: A systematic review. Acta Trop.
  4. Babu S, Nutman TB. Immunology of lymphatic filariasis. Parasite Immunol. 2013 Oct 17.
  5. Weil GJ, Curtis KC, Fakoli L, Fischer K, Gankpala L, Lammie PJ, Majewski AC, Pelletreau S, Won KY, Bolay FK, Fischer PU. Laboratory and field evaluation of a new rapid test for detecting Wuchereria bancrofti antigen in human blood. Am J Trop Med Hyg. 2013 Jul;89(1):11-5.
  6. Chew LL, Teh HS. The filarial dance sign in scrotal filarial infection: a case report. J Clin Ultrasound. 2013 Jul-Aug;41(6):377-9.
  7. Tisch DJ, Michael E, Kazura JW. Mass chemotherapy options to control lymphatic filariasis: a systematic review. Lancet Infect Dis. 2005;5:514.
  8. Palumbo E. Filariasis: diagnosis, treatment and prevention. Acta Biomed. 2008 Aug; 79:106-9.
  9. Debrah AY, Mand S, Marfo-Debrekyei Y, Batsa L, Pfarr K, Lawson B, Taylor M, Adjei O, Hoerauf A Reduction in levels of plasma vascular endothelial growth factor-A and improvement in hydrocele patients by targeting endosymbiotic Wolbachia sp. in Wuchereria bancrofti with doxycycline. Am J Trop Med Hyg. 2009;80(6):956.
  10. Pani SP, Das LK, Vanamail P. Tolerability and efficacy of a three-age class dosage schedule of Diethylcarbamazine citrate (DEC) in the treatment of microfilaria carriers of Wuchereria bancrofti and its implications in mass drug administration (MDA)strategy for elimination of lymphatic filariasis (LF). J Commun Dis. 2005 Mar;37(1):12-7.
  11. Rebollo MP, Bockarie MJ. Toward the elimination of lymphatic filariasis by 2020: treatment update and impact assessment for the endgame. Expert Rev AntiInfect Ther. 2013 Jul;11(7):723-31.

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Last updated: 2019-07-11 22:33