Mosquito
Mosquito-borne diseases are currently most prevalent in East Africa, Latin America,  Southeast Asia, and India; however, emergence of vector-borne diseases in Europe have recently been observed. A weighted risk analysis demonstrated associations to climate for 49% of infectious diseases in Europe including all transmission routes. One statistical model predicts by 2030, the climate of southern Great Britain will be climatically-suitable for malaria transmission "Plasmodium vivax" malaria for 2 months of the year. By 2080 it is predicted that the same will be true for southern Scotland.
Onchocerciasis
Onchocerciasis, also known as river blindness, is a disease caused by infection with the parasitic worm "Onchocerca volvulus". Symptoms include severe itching, bumps under the skin, and blindness. It is the second-most common cause of blindness due to infection, after trachoma.
The parasite worm is spread by the bites of a black fly of the "Simulium" type. Usually, many bites are required before infection occurs. These flies live near rivers, hence the common name of the disease. Once inside a person, the worms create larvae that make their way out to the skin, where they can infect the next black fly that bites the person. There are a number of ways to make the diagnosis, including: placing a biopsy of the skin in normal saline and watching for the larva to come out, looking in the eye for larvae, and looking within the bumps under the skin for adult worms.
A vaccine against the disease does not exist. Prevention is by avoiding being bitten by flies. This may include the use of insect repellent and proper clothing. Other efforts include those to decrease the fly population by spraying insecticides. Efforts to eradicate the disease by treating entire groups of people twice a year are ongoing in a number of areas of the world. Treatment of those infected is with the medication ivermectin every six to twelve months. This treatment kills the larvae but not the adult worms. The antibiotic doxycycline weakens the worms by killing an associated bacterium called "Wolbachia", and is recommended by some as well. The lumps under the skin may also be removed by surgery.
About 15.5 million people are infected with river blindness. Approximately 0.8 million have some amount of loss of vision from the infection. Most infections occur in sub-Saharan Africa, although cases have also been reported in Yemen and isolated areas of Central and South America. In 1915, the physician Rodolfo Robles first linked the worm to eye disease. It is listed by the World Health Organization (WHO) as a neglected tropical disease.