Three more Cambodian children were tested positive for Enterovirus 71 (EV-71) over the weekend and two of them were killed by the disease, bringing the death toll to 56 since April, a senior health official said Tuesday.

Ly Sovann, deputy director of the Health Ministry's communicable disease control department, told Xinhua that the two dead children were in Kampong Cham province, some 124 km east of Phnom Penh, and the other one is recovering from the disease at the Kantha Bopha Children's Hospital in Siem Reap province.

Cambodia has been plagued by EV-71, which causes hand, foot and mouth disease (HFMD) since April. The severe form of HFMD has killed at least 56 Cambodian children so far.

The Ministry of Education last week ordered the close of all kindergartens and primary schools across the country, two weeks earlier than the scheduled annual vacation, in fears of the disease.

HFMD virus is contagious and infection spreads from person to person by direct contact with nose or throat discharges, saliva, fluid from blisters or the stool of infected persons, according to the World Health Organization.

Good hygiene practice can prevent HFMD. Presently, there is no specific treatment available for HFMD, it said. Parents should seek medical advice if their children develop high fever, vomiting, lethargy and limb weakness.