Epidemics of cholera, malaria, rabies and African hemorrhagic fevers like Marburg hemorrhagic fever, are common diseases in several parts of the country. Many regions in this country have high incidence rates of tuberculosis and high HIV prevalence rates. Dengue, filariasis, leishmaniasis and onchocerciasis (river blindness) are other diseases carried by insects that also occur in the region. Angola has one of the highest infant mortality rates in the world and one of the world's lowest life expectancies. A 2007 survey concluded that low and deficient niacin status was common in Angola. Demographic and Health Surveys is currently conducting several surveys in Angola on malaria, domestic violence and more.