Encyclopedia

Wushereriosis

Wuchereriosis is a helminthiasis that is caused by filamentous parasites – filariae that circulate in the blood. According to various estimates, around 80 million people worldwide suffer from this disease.

What are the causes?

Wuchereriosis is caused by Wuchereria bancrofti, common in countries located in tropical and subequatorial climate zones. Single cases of the disease have been registered in Bulgaria, and several cases have also been confirmed in the territory of the former USSR and in Central Asia.

Sexually mature filariae mainly inhabit the lymph glands and vessels. As a result of their blockage, inflammatory thickening of their walls develops, as well as stagnation of the lymphatic fluid. Affected areas greatly increase in size.

The female parasites “produce” a large number of larvae, each about 0.3 mm long, called “nocturnal microfilariae” because they appear at night and during the day penetrate deep into the body’s tissues, most -often in the pulmonary vessels, heart and kidneys.

This periodicity is related to the characteristics of the distribution of the parasites, which passes through an intermediate host, namely the various blood-sucking mosquitoes.

When the insects suck blood from the filariae in the evening or at night, their larvae enter the mosquito’s stomach and then penetrate its body cavities.

There they mature to a certain extent and subsequently accumulate at the base of the insect’s blood-sucking proboscis. When sucking blood from a healthy person, this mosquito breaks the integrity of his skin with its proboscis.

At the same time, the filaria larvae emerge from the base of the mosquito’s blood-sucking apparatus and penetrate the skin and subsequently the blood of a healthy person.

Wuchereria bancrofti is the most common of the filaria parasitic in humans. The parasite is found mainly in tropical and subequatorial climate areas and less often in subtropical, Asia, Oceania, places in South America and in the countries of the Caribbean.

Man is the only definitive host of Wuchereria bancrofti. Sexually mature worms of this species can live in the human body for a very long time – on average about 17 years, larvae in the bloodstream die within 70 days.

According to the terminology adopted by the Committee of Experts on Filariasis of the World Health Organization, subperiodic and periodic strains of microfilariae are distinguished.

Larvae of Wuchereria bancrofti /Microfilaria nocturna/ during the day are found in the pulmonary blood vessels, and at night they migrate to the peripheral vessels.

The microfilariae of Wuchereria bancrofti of the subperiodic strain found in the Pacific region and therefore named W. Pacifica are present in the peripheral blood around the clock, but during the light part of the day their number increases significantly.

What are the symptoms?

The duration of the incubation period for all filariasis varies between 3 and 18 months.

The initial symptoms are also identical – allergic manifestations. For the second stage of the development of the disease, occurring 2-7 years after the initial infestation, periods of relative absence of symptoms are characterized by periods of exacerbation.

It is also considered common to see enlargement of the groin and thigh lymph nodes during the second phase.

Wuchereriosis treatment

As with other filariasis, it is considered effective to use the drug albedanzole, which is an anthelmintic preparation with a wide spectrum of action.

According to the recommendations of the WHO for the treatment of filariasis, it is desirable to combine two preparations, and for this purpose albedanzole is used in combination with ivermectin. The use of antihistamine preparations is also imperative.

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