West Nile Desease is an infection caused by a Flavivirus: the West Nile virus. Transmitted by the mosquito of the Culex genus. The reservoir of the virus consists of birds. The disease initially affected Africa, part of central and southern Europe, the Middle East, and India. A gradual expansion is being observed with a spread across the American continent from East to West, and to Eastern Europe and Russia. West Nile is frequently asymptomatic but it can cause feverish states accompanied sometimes by neurological signs presenting a clinical picture of encephalitis or flaccid paralysis. There is a risk of death or serious sequelae. The treatment is symptomatic. Vaccine trials are underway.
Lyme Disease
Lyme disease is an infection caused by a a species of bacteria of the Borrelia genus: Borrelia burgdorferi transmitted by the bite of a tick of the Ixodes genus. 10 to 15% of them carry the Borrelia bacteria. The risk of contamination by tick bite varies between 1 and 6% depending on the region. The disease is found in the northern hemisphere, in America and in Eurasia during the active phase of the ticks, between May and October. The disease begins with a red skin lesion centered around the tick bite that gradually spreads out and ends up disappearing within a few days or a few weeks. A few weeks or a few months later, other signs may appear, involving the joints, the nervous system (paralysis and pain), heart rhythm abnormalities and, more rarely, other symptoms. The expression of the disease is usually more severe in Northern America than in Europe. The treatment relies on antibiotics. Admission to hospital can be necessary.
The Leishmaniases
The leishmaniases are parasite diseases caused by Leishmania (unicellular parasites that infect the reticulohistiocytic system) transmitted by a species of sand fly (subfamily Phlebotominae). A distinction can be made, according to the type of parasite, between the cutaneous, mucocutaneous and visceral forms. The cutaneous and mucocutaneous forms have a different aspects on the American continent compared with Asia. The various forms of the disease have as a common feature, the creation of chronic ulcers, more or less hollow, without a tendency to heal. These diseases have specific treatments, which need to be followed over long periods of time in order to achieve a cure.