Filariasis: From 5 Different Sources
A group of tropical diseases, caused by various parasitic worms or their larvae, which are transmitted to humans by insect bites.
Some species of worm live in the lymphatic vessels. Swollen lymph nodes and recurring fever are early symptoms. Inflammation of lymph vessels results in localized oedema. Following repeated infections, the affected area, commonly a limb or the scrotum, becomes very enlarged and the skin becomes thick, coarse, and fissured, leading to a condition known as elephantiasis. The larvae of another type of worm invade the eye, causing blindness (see onchocerciasis). A third type, which may sometimes be seen and felt moving beneath the skin, causes loiasis, characterized by irritating and sometimes painful areas of oedema called calabar swellings.
The diagnosis of filariasis is confirmed by microscopic examination of the blood. The anthelmintic drugs diethylcarbamazine or ivermectin most often cure the infection but may cause side effects such as fever, sickness, muscle pains, and increased itching. Diethylcarbamazine can be given preventively, and the use of insecticides and protective clothing help to protect against insect bites. (See also roundworms; insects and disease.)
The term used to describe several clinical entities caused by one or other of the nematode ?lariae; these include Wuchereria bancrofti/Brugia malayi, Onchocerca volvulus, Loa loa, Dracunculus medinensis (DRACONTIASIS or guinea-worm disease), Mansonella perstans, etc. These organisms have widely di?ering geographical distributions. Whereas lymphatic ?lariasis is present throughout much of the tropics and subtropics, ONCHOCERCIASIS (river-blindness) is largely con?ned to west and central Africa and southern America. Loaiasis is an infection of west and central Africa, and dracontiasis involves west and central Africa and western India only.
Clinically, the lymphatic ?lariases characteristically cause ELEPHANTIASIS (lymphoedema); onchocerciasis gives rise to ophthalmic complications (river-blindness), rashes and subcutaneous nodules; loaiasis causes subcutaneous ‘Calabar swellings’ and subconjunctival involvement; and dracontiasis predisposes to secondary bacterial infections (usually involving the lower limbs). Diagnosis is by ?nding the relevant ?larial nematode, either in blood (day and night ?lms should be examined), or in one or other of the body ?uids. An EOSINOPHILIA is often present in peripheral blood. Serological diagnosis is also of value. In onchocerciasis, skin-snips and the Mazotti reaction are valuable adjuncts to diagnosis.
The mainstay of chemotherapy consists of diethylcarbamazine (aimed predominantly at the larval stage of the parasite). However, ivermectin (not available in the UK) is e?ective in onchocerciasis, and metronidazole or one of the benzimidazole compounds have limited value in dracontiasis. Suramin has been used to kill adult ?larial worms. Prevention consists of eradication of the relevant insect vector.
A parasitic infection caused by filarial nematode worms, such as Wuchereria bancrofti and Brugia malayi, causing a variety of illnesses. See also elephantiasis and onchocerciasis.
Infection with filarial nematode worms
n. a disease, common in the tropics and subtropics, caused by the presence in the lymph vessels of the parasitic nematode worms Wuchereria bancrofti and Brugia malayi (see filaria). The worms, which are transmitted to humans by various mosquitoes (including Aëdes, Culex, Anopheles, and Mansonia), bring about inflammation and eventual blocking of lymph vessels, which causes the surrounding tissues to swell (see elephantiasis). The rupture of urinary lymphatics may lead to the presence of *chyle in the urine. Filariasis is treated with the drug *diethylcarbamazine.
Marked swelling and inflammation of the lymphatics, associated with hypertrophy and thickening of the overlying skins and subcutaneous tissues, usually in the lower limbs and external genitalia. While not exclusive to filariasis, it is seen often in chronic filariasis due to Wuchereria bancrofti and Brugia malayi. The affected areas often taken on a woody character and can be extensive. See also filariasis.... elephantiasis
A mosquito genus in the subfamily Anophelinae. Only certain species transmit human malaria and filariasis.... anopheles
(Syn. “river blindness”) A. disease caused by the parasitic filarial nematode Onchocerca volvulus. (See also filariasis).... onchocerciasis
The passage of CHYLE in the urine. This results in the passing of a milky-looking urine. It is one of the manifestations of FILARIASIS, where it is due to obstruction of the LYMPHATICS by the causative parasite.... chyluria
Most mosquitoes that are not anophelines fall into this group. Culicines are not vectors of human malaria, but the subfamily includes the important genera Aedes, Culex and Mansonia. May transmit a number of diseases (eg, yellow fever, dengue fever, filariasis, viral encephalitis).... culicine
A FILARICIDE derived from PIPERAZINE used to treat FILARIASIS – a group of diseases caused by parasitic worms called nematode ?lariae.... diethylcarbamazine citrate
A generic term for drugs used to treat ?larial infections (see FILARIASIS).... filaricide
Immature developing (L1 and L2) and infective (L3) stages of nematode larvae, e.g. filariasis, hookworm etc.... In filariasis, after an infective blood meal, microfilariae exsheath, penetrate the stomach wall and pass into the haematocoele, from where they migrate to the thoracic muscles of the mosquito. In the thorax, the small larvae become more or less inactive, grow shorter but considerably fatter and develop, after 2 days, into “sausageshaped” forms (L1). They undergo two (2) moults and the resultant third stage larvae (L3) become active. This is the infective stage and is formed some 10 days or more after the microfilariae have been ingested with a blood meal.... l1, l2, and l3
Lymphangiectasis means an abnormal dilatation of the lymph vessels, as in FILARIASIS.... lymphangiectasis
A genus of mosquitoes, some species of which can be involved in the transmission of human filariasis due to Brugia malayi and Wuchereria bancrofti.... mansonia
One of the Romanowski stains used to stain blood films and blood parasites such as those causing relapsing fever, malaria trypanosomiasis and filariasis.... wright’s stain
n. a genus of widely distributed mosquitoes occurring throughout the tropics and subtropics. Most species are black with distinct white or silvery-yellow markings on the legs and thorax. Aëdes species are not only important as vectors of *dengue, *yellow fever, *filariasis, and Group B viruses causing encephalitis but also constitute a serious biting nuisance. A. aegypti is the principal vector of dengue and yellow fever.... aëdes
n. a genus of threadlike parasitic worms (see filaria). B. malayi infects humans throughout southeast Asia, causing *filariasis and *elephantiasis (especially of the feet and legs). B. pahangi, a parasite of wild cats and domestic animals, produces an allergic condition in humans, with coughing, breathing difficulty, and an increase in the number of *eosinophils in the blood. Brugia undergoes part of its development in mosquitoes of the genera Anopheles and Mansonia, which transmit the parasite from host to host.... brugia
n. a genus of mosquitoes, worldwide in distribution, of which there are some 600 species. Certain species are important as vectors of filariasis (see also Wuchereria) and viral encephalitis.... culex
Relatively few insect species cause disease directly in humans. Some parasitize humans, living under the skin or on the body surface (see lice; chigoe; myiasis). The most troublesome insects are flies and biting insects. Flies can carry disease organisms from human or animal excrement via their feet or legs and contaminate food or wounds.
A number of serious diseases are spread by biting insects.
These include malaria and filariasis (transmitted by mosquitoes), sleeping sickness (tsetse flies), leishmaniasis (sandflies), epidemic typhus (lice), and plague (rat fleas).
Mosquitoes, sandflies, and ticks can also spread illnesses such as yellow fever, dengue, Lyme disease, and some types of viral encephalitis.
Organisms picked up when an insect ingests blood from an infected animal or person are able to survive or multiply in the insect.
Later, the organisms are either injected into a new human host via the insect’s saliva or deposited in the faeces at or near the site of the bite.
Most insect-borne diseases are confined to the tropics and subtropics, although tick-borne Lyme disease occurs in some parts of the.
The avoidance of insect-borne disease is largely a matter of keeping flies off food, discouraging insect bites by the use of suitable clothing and insect repellents, and, in parts of the world where malaria is present, the use of mosquito nets and screens, pesticides, and antimalarial tablets.... insects and disease
n. an anthelmintic drug that destroys filariae and is therefore used in the treatment of filariasis and loiasis. Side-effects may include headache, malaise, joint pains, nausea, and vomiting.... diethylcarbamazine
n. 1. an animal, usually an insect or a tick, that transmits parasitic microorganisms – and therefore the diseases they cause – from person to person or from infected animals to human beings. Mosquitoes, for example, are vectors of malaria, filariasis, and yellow fever. 2. an agent used to insert a foreign gene or DNA fragment into a bacterial or other cell in *genetic engineering and *gene therapy. Viruses, especially retroviruses, are often used as vectors: once inside the host cell, the virus can replicate and thus produce copies (*clones) of the gene.... vector
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