(CNN) An outbreak of contagious and deadly Marburg virus disease in the Kween district of eastern Uganda was declared by the nation’s Ministry of Health on October 19.

Marburg virus disease, which causes severe viral hemorrhagic fever, ranks among the most virulent pathogens known to infect humans, according to the World Health Organization.

As of Saturday, two confirmed cases, one probable case and two suspected cases have been reported in the Kween district, on the border with Kenya, Tarik Jaarevi, a spokesman for the WHO, wrote in an email. The confirmed and probable cases — two brothers and a sister — have died.

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