What is periodicity of microfilaria?

This term has come to mean a periodic increase in numbers in peripheral capillary blood of the embryos of filariae. This, in the case of Filaria bancrofti, occurs during the hours of sleep, and of Filaria loa, during the hours of activity. Smith, A. J., and Rivas, Damaso: Notes Upon Human Filariasis , Am.

Why is there nocturnal periodicity of microfilariae?

Microfilariae were found to have great difficulty in passing through the peripheral capillaries. Microfilariae are less active in day blood than in night blood. It is suggested that because of this, they are not able to work their way through the capillaries in the daytime, hence the mechanism of nocturnal periodicity.

Where can you find the microfilaria during daytime?

During the day-time they accumulate in the small vessels of the lungs, and hence they are few in the peripheral blood; this phase is probably adapted to allow the microfilariae to enjoy favourable physiological conditions in the lungs.

What are the identifying characteristics of microfilariae?

Structure and Classification. Adult Wuchereria and Brugia are elongated and slender (30 to 100 mm by 100 to 300 μm); males are about half the size of females. Microfilariae are the diameter of a red blood cell and 250 to 300 μm long. They are enclosed in a characteristic sheath.

What is microfilaria larva?

Microfilaria is the term used to refer to the larva of a certain parasitic nematode, i.e., filariae when it is still in an early larval stage. These parasites are released into the bloodstream of the host by the adult parasites. And hence, these embryonic larvae are usually found in the blood of an infected person.

What is occult filariasis?

Occult Filariasis is a term used to designate lesions in which microfilariae are not found in peripheral blood, although they may be seen in tissues. These lesions present differently from those with classical disease and resemble many non – filarial lesions from which they are difficult to distinguish clinically.

How is filaria detected?

The standard method for diagnosing active infection is the identification of microfilariae in a blood smear by microscopic examination. The microfilariae that cause lymphatic filariasis circulate in the blood at night (called nocturnal periodicity).

What are the four filarial worms?

Filaria consist of a group of tissue nematodes, including Wuchereria bancrofti, Brugia malayi, and Brugia timori, which cause lymphatic filariasis, Onchocerca volvulus, which causes onchocerciasis (river blindness), and Loa loa, which causes loiasis.

How long do microfilariae live?

The worms can live for approximately 6–8 years and, during their lifetime, produce millions of microfilariae (immature larvae) that circulate in the blood. Mosquitoes are infected with microfilariae by ingesting blood when biting an infected host. Microfilariae mature into infective larvae within the mosquito.

What kills microfilaria?

Diethylcarbamazine (DEC) is the drug of choice in the United States. The drug kills the microfilariae and some of the adult worms. DEC has been used world-wide for more than 50 years.

What are the signs of filaria?

Symptoms may include itchy skin (pruritis), abdominal pain, chest pain, muscle pain (myalgias), and/or areas of swelling under the skin. Other symptoms may include an abnormally enlarged liver and spleen (hepatosplenomegaly), and inflammation in the affected organs.