User:Mohrra3748/Onchocerciasis

Prevention: Effective prevention efforts include personal protection from black fly bites. Recommended protection measures include using insect repellents and wearing long sleeves and pants to eliminate exposed skin

In April of 2013, Colombia became the first country to achieve elimination of Onchocerciasis, verified by the World Health Organization. In the following three years, Ecuador and Guatemala, along with Mexico have been verified to have eliminated Onchocerciasis, with the use of ivermectin. Disease Outcomes: Onchocerciasis is the second leading cause of blindness from infectious causes. Main disease symptoms, such as blindness and itching, contribute to disease burden by limiting the infected individuals ability to live and work. Individuals most at risk are those who live or work in areas where simulium blackflies are most common, mostly near rivers and streams. Rural agricultural areas in sub-Saharan Africa see the most disease burden by blackfly bites. Onchocerciasis common to tropical environments, like that of sub-Saharan Africa, where more than 99% percent of infected individuals occupy the 31 countries. Onchocerciasis can be linked to impoverished remote areas, as residents who experience symptoms can no longer tend to land or navigate the area. In these areas, men have been found to be more likely than women to be exposed to blackfly bites, since they participate more in activities like farming, fishing, or hunting. Areas with high infection rates may experience up to one-third of residents affected by onchocerciasis symptoms. The age group most impacted by the disease are individuals age 61+ years.

In 2017, the Global Burden of Disease study said that an estimated 220 million people needed preventive chemotherapy for onchocerciasis. Of those infected, 14.6 million had skin disease and 1.15 million were experiencing vision loss.

In 2017 the WHO set up the Onchocerciasis Technical Advisory Subgroup (OTS) to further research and establish areas that require drug administration. The OTS also identifies co-endemic areas with lymphatic filariasis to properly treat Onchocerciasis and lymphatic filariasis.

The WHO priorities research to achieve elimination of onchocerciasis. Research approaches include: improving outreach efforts to marginalized populations, expanding mapping of endemic areas of onchocerciasis, improve and standardize information on mass drug administration, develop diagnostic approaches, surveillance strategies, and therapeutic approaches

A skin biopsy removes approximately 2 mg of skin tissue by sclerocorneal biopsy punch or shaving a cone of skin with a scalpel. The skin tissue sample is analyzed for the parasite larvae using a microscope. Nodulectomy can be used to analyze skin nodules for the presence of parasites. Slit lamp eye exams are used to identify signs of the parasites in and around the eyes of patients whose eyes are effected. Antibody tests when available can aid in the diagnosis of Onchocerciasis.

The Onchocerca volvulus main habitat is fast flowing rivers, Onchocerciasis is more commonly found along the large rivers in northern and central regions of the Africa. With a decrease in cases as you move farther away from those rivers. Multiple exposure to Simulium blackflies raise the number of adult worms and microfilariae that are present in the host. Risk of contracting Onchocerciasis for causal travelers is low, since it often takes several exposures, while travelers that stay for longer visits such as missionaries or long-term volunteers have a greater risk of contracting Onchocerciasis.

After two decades of research, moxidectin was approved by the U.S. Food and Drug Administration in 2018 for use in ages 12 and older. Ongoing studies are looking to identify doses that will be safe for children ages 4-11. The oral dosage for moxidectin in adults and children 12 and up is 8 mg in a single dose. Moxidectin has been found to more strongly suppress the O. volvulus microfilariae for longer than ivermectin treatments, with peak clearance of microfilariae in the skin at one month after treatment. At six months post treatment, many individuals treated with moxidectin have no detectable microfilariae present in their skin.

In 2021, Nigeria had the greatest prevalence of onchocerciasis infections globally, and attributed the infection to 30.2% of blindness cases in the country. A study from western Nigeria found that residents believed that the parasitic effects of the disease was necessary to stimulate fertility, and that the disease was thought to be carried by all residents.

Using insect repellent that contains N,N-Diethyl-meta-toluamide (DEET) as well as clothing treated with permethrin, an insecticide, can provide additional protection from black fly bites.

Bibliography

CDC

WHO

NIH