Doctors are inspecting all the children of a village in the Amur region in Russia's Far East to determine what caused the death of two sisters on Thursday, the Interfax news agency reported.
Regional Health Minister Nikolai Tezikov told journalists that after the girls' death, a team of medics was sent to the village of Talala, where they lived.
"We examined all the children in the village of Talala, and we also inspected the school that children from this village attend," Tezikov said.
He called rumors of a new strain of meningitis "premature," and said that the doctors suspect poison as the likely cause of death.
The sisters, aged 13 and 5, died in an ambulance on the way to the hospital. Their 12-year-old brother has been hospitalized in the infectious diseases hospital. Doctors reported that the girls had hemorrhaging in their adrenal glans which could have been caused by a number of agents, including medications or poison.