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RIO DE JANEIRO, March 25 (Xinhua) -- The number of dengue fever cases in Rio de Janeiro city this year has already surpassed 10,000, local health authorities said on Friday.
According to the city's Health Secretariat, in less than three months, the number of confirmed dengue fever cases in Rio reached 10,158, exceeding the figures registered in the entire years of 2009 (2,723) and 2010 (3,120).
In Rio de Janeiro state, the number of confirmed dengue fever cases reached 20,150, and the death toll rose to 18.
This week, the first two cases of type-4 dengue fever in Rio de Janeiro state were confirmed in the city of Niteroi. The type-4 dengue fever is not more dangerous than the other types, but as the disease had not been registered in the region before, the local population has no immunity to it.
As there are four different types of dengue fever, a person can develop the disease several times.
The last epidemic of dengue fever in Rio de Janeiro state occurred in 2008 when 174 people died of the disease and some 250,000 cases of dengue were registered.