The genome sequences generated here will enable us to study crucial phenotypic differences, including drug resistance, between these closely related filarial species. In addition, these data will allow us to start to define the extent of synteny, to characterize heterozygosity and produce microsatellite makers, which will help us plan the more comprehensive studies of population genetics that are needed. Finally, from a practical point of view, there is an extreme need to generate proteomic information from these parasites that requires this genomic data to interpret them.
We targeted Loa loa for this initial work for two important reasons. First, among the four pathogenic filarial parasites described above, Loa loa is the least well studied. However, Loa loa , is gaining clinical prominence because of serious adverse events following treatment, including death. As a result, the parasitological community has called for a better understanding of this organism to promote better methods of diagnosis, treatment and prevention.
A second justification for prioritizing Loa loa is the fact that unlike any of the other filarial parasites of humans, Loa loa does not contain the alpha-proteobacterial endosymbiont, Wolbachia. This suggests that either there has been lateral transfer of important bacterially-encoded genes or that the obligate relationship between the endosymbiont and its filarial host is dispensable.
Initial analysis of the B. Testing this and understanding the comparable adaptations of Loa loa will be extremely important to understand the potential impact of the endosymbiont on pathogenicity.
After many years, the legs, arms, and genitals may become massively enlarged and disfigured. Circulating microfilariae of Wuchereria or Brugia can induce allergic reactions in the lungs resulting in cough, shortness of breath, and asthma-like symptoms.
Adult Loa loa worms migrate under the skin causing temporary nodules and occasionally cross the eye under the clear, outer membrane conjunctiva.
Adult Onchocerca live in nodules under the skin and produce microfilariae that cause itching and damage to the skin. They also enter the eye and cause inflammation and scarring that can result in blindness after many years. Merck and Co. From developing new therapies that treat and prevent disease to helping people in need, we are committed to improving health and well-being around the world.
The Manual was first published in as a service to the community. Learn more about our commitment to Global Medical Knowledge. This site complies with the HONcode standard for trustworthy health information: verify here. Common Health Topics. This is not always feasible because in most parts of the world, microfilariae are nocturnally periodic, which means that they only circulate in the blood at night.
For this reason, the blood collection has to be done at night to coincide with the appearance of the microfilariae in the blood. Serologic techniques provide an alternative to microscopic detection of microfilariae for the diagnosis of lymphatic filariasis.
Because lymphedema may develop many years after infection, lab tests are often negative with these patients. Avoiding mosquito bites is the best form of prevention. The mosquitoes that carry the microscopic worms usually bite between the hours of dusk and dawn. If you live in or travel to an area with lymphatic filariasis:. People infected with adult worms can take a yearly dose of medicine, called diethylcarbamazine DEC , that kills the microscopic worms circulating in the blood.
While this drug does not kill all of the adult worms, it does prevent infected people from giving the disease to someone else. People with lymphedema and elephantiasis are not likely to benefit from DEC treatment because most people with lymphedema are not actively infected with the filarial parasite. People with lymphedema and hydrocele can benefit from lymphedema management, and in the case of hydrocele surgical repair. Even after the adult worms die, lymphedema can develop. You can ask your physician for a referral to see a lymphedema therapist for specialized care.
Prevent the lymphedema from getting worse by following several basic principles:. Contact Us. Skip directly to site content Skip directly to page options Skip directly to A-Z link. Filarial diseases are caused by parasitic worms that are transmitted by the bite of blood-feeding insects. This debilitating group of diseases includes river blindness and lymphatic filariasis commonly known as elephantiasis.
Onchocerciasis, commonly known as river blindness, is a filarial disease caused by the parasitic nematode worm Onchocerca volvulus. People are infected by worms transmitted by the bite of blood-sucking blackflies, which breed in fast-flowing rivers.
River blindness is not usually fatal, but it inflicts hardship and misery on millions of people. In the human body, the adult worms produce embryonic larvae microfilariae that migrate to the skin, eyes and other organs. The worms can cause severe itching, disfiguring skin conditions, and blindness or impaired vision. Individuals with a very high amount of Loa loa larvae microfilariae in the blood are at risk of life-threatening complications if they receive ivermectin, a drug for river blindness.
Current treatment for river blindness is based on repeated mass drug administration MDA of ivermectin to everyone living in an affected area. The drugs kill juvenile worms and temporarily sterilize adult worms. The adult worms remain alive in the body, eventually producing new offspring, often before the next MDA takes place. As a result, MDA must be repeated for many years.
WHO has targeted the elimination of river blindness in Latin America, in some African countries, and in Yemen by
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