RIO DE JANEIRO, April 28 (RIA Novosti) - An ongoing dengue fever outbreak in northeast Brazil has claimed 47 lives since January, the country's Health Ministry said on Monday.

According to ministry statistics, 55,000 people in Bahia, the fourth most populous Brazilian state, are currently registered as dengue fever sufferers, a 220% increase from the same period of last year.

Authorities have declared a state of emergency in seven cities and requested aid from the federal government to cope with the disease.

Dengue is passed from human to human via mosquitoes or blood transfusions. Its symptoms are the sudden onset of severe headache, high fever, and muscle and joint pains, and are often diagnosed as influenza. It is also known as break-bone fever or bonecrusher disease due to severe pain experienced in the joints.

According to the World Health Organization, the disease is now epidemic in more than 100 countries.