Dengue and dengue haemorrhagic fever: Caused by one of four closely related viruses (DEN-1, DEN-2, DEN-3, and DEN-4).
Spread by Aedes aegypti, a domestic, day-biting mosquito. Symptoms are sudden high fever, severe frontal headache, pain behind the eyes which worsens with eye movement, muscle and joint pains, measles-like rash over chest and upper limbs, nausea and vomiting. Severe and fatal hemorrhagic disease may occur. Over 80 outbreaks reported in India.
Japanese encephalitis: Caused by Culex tritaeniorhynchus that breeds in flooded rice fields, marshes, and standing water. Can infect humans, domestic animals, birds, bats, snakes, and frogs. The virus invades the central nervous system but may or may not cause symptoms. In severe cases, appears as flu-like illness that may progress to a serious brain infection and can be fatal in 30 per cent of cases. Among the survivors, another 30 per cent will have serious brain damage, including paralysis. Over the past decade, 15 states and Union Territories have reported JE, with the biggest outbreak occurring in eastern UP in 2005.
Chikungunya: Spreads through the bite of the Aedes mosquito, which also causes dengue. Symptoms include headache, fever, fatigue, nausea, vomiting, muscle pain, rash, and joint pain. Originally from Africa, chikungunya recurred in India after 32 years in 2006. There is no vaccine against the disease and treatment is symptomatic. According to the Union Ministry of Health, the disease does not kill but causes severe and painful deformity of the limbs that can last several months.
Lymphatic Filariasis: Commonly known as elephantiasis. Is a disfiguring and disabling disease. In the early stages, the lymphatic system gets damaged. In India, 99.4 per cent of the cases are caused by Wuchereria bancrofti. Culex quinquefasciatus transmits filariasis. The long-term physical consequences are painful swollen limbs (lymphoedema or elephantiasis). The National Health Policy 2002 aims at the elimination of lymphatic filariasis by 2015.