Wuchereria bancrofti is the name given to a species of nematode. It is a parasite that infects the lymphatic vessels of humans.
What is Wuchereria bancrofti?
Wuchereria bancrofti is called a parasite that belongs to the nematode family. Like other nematode species, for example Brugia timori and Brugia malayi, it is capable of colonizing the human lymphatic system and causing health damage. Thus, around the globe, an estimated 80 to 120 million people suffer from lymphatic filariasis. This disease is caused by Wuchereria bancrofti in nine out of ten cases. The name Wuchereria bancrofti is derived from the German-Brazilian physician Otto Wucherer (1820-1873), who detected the nematode in the urine of a patient in 1856. In doing so, he determined that the parasite was responsible for the outbreak of lymphatic filariasis. Another discoverer is considered to be the British-Australian parasitologist John Bancroft (1836-1884), who also served as the eponym.
Occurrence, distribution, and characteristics
The distribution areas of Wuchereria bancrofti primarily include China, Central and South America, the Caribbean, Africa, and the Pacific region. There the nematodes are found in tropical areas. In Germany, infestation with the filariae is very rare, and they are usually transmitted in the risk areas described. Male specimens of Wuchereria bancrofti reach a size between 2.4 and 4 centimeters. The females even reach a size of 5 to 10 centimeters. However, they have a thickness of only 0.3 millimeters. The microfilariae (larvae) are equipped with a seedless tail end. Their maximum size ranges from 250 to 300 micrometers. The parasites usually live for a maximum of eight years. The prepatency period, i.e. the time between infection and detection of the parasites’ reproductive products, is about nine months. Mosquitoes serve as intermediate hosts for Wuchereria bancrofti. These include in particular the mosquito species Anopheles, Aedes and Culex. The mosquitoes transmit the parasites to humans during the biting process. Survival of the nematode is not possible outside of mosquitoes and humans. If a mosquito bites an already infected person, tiny larvae are ingested by the mosquito by sucking, and these larvae are found in human blood. During the subsequent biting process, the parasites then pass to another person, where they penetrate the lymph nodes and lymph vessels. There they remain for about nine months and develop into adult filariae. Overall, survival of the worms in the lymphatic system is possible for several years. During this period, countless new microfilariae are produced by their females. Especially during the night hours, the transfer into the peripheral blood takes place. In this area they can infect a mosquito again. In this process, the microfilariae are able to adapt to the biting habits of insects that prefer to infest humans at night.
Diseases and ailments
Wuchereria bancrofti is among the parasites that are harmful to health and can cause more or less severe diseases. Mild forms of disease include lymphadenitis (abnormal swelling of the lymph nodes) and lymphangitis (inflammation of the lymph nodes). In severe cases, lymphatic filariasis is imminent. Most sufferers live in India and Africa and account for one third of all patients. The other cases of the disease are in the south of Asia, in Pacific countries and South America. The World Health Organization (WHO) classifies 1.1 billion people as at risk for infestation with Wuchereria bancrofti. The first symptoms caused by the nematodes appear several weeks or even several months after infection with the parasites. During the acute phase, affected individuals suffer from chills, fever and swollen lymph nodes. It is not uncommon for swelling of the feet or legs to occur. Both unilateral and bilateral symptoms are possible. After a few days, the symptoms improve again and the skin begins to flake. In some patients, the swellings appear several times. Lymphatic filariasis is not always accompanied by fever. However, if fever occurs, it is considered a reaction of the organism to dead nematodes within the lymph nodes or lymphatics.In males, fluid may accumulate on the genitals. If the nematodes remain in the human body for a long time, there is a risk of chronic lymphatic filariasis, in the course of which lymphedema often develops. In the case of such lymphatic congestion, physicians speak of elephantiasis (elephant syndrome), which primarily affects the groin area, the feet and the legs. Less frequently affected, however, are the chest, arms and genitals. Some patients also suffer from rheumatic complaints such as myositis (muscle inflammation) or arthritis. Another characteristic is a milky-cloudy coloration of the urine. In some people, however, an infestation with Wuchereria bancrofti does not cause any symptoms at all. Detection of Wuchereria bancrofti in the human body is possible by blood smear. In some cases, the blood is taken at night for this purpose, since the parasites are in body regions infested by mosquitoes during this period. Anthelmintics such as ivermectin are used to control Wuchereria bancrofti. This drug can kill the microfilariae. Albendazole or diethylcarbamazine (DEC) can be administered as additional drugs. In this way, the beneficial effect of the treatment is increased.
