A two-year-old boy who died this month was killed by a strain of enterovirus 71 similar to one thought to have claimed at least 80 lives in Taiwan and Malaysia, officials said yesterday. The Department of Health confirmed that both the boy and his three-year-old sister had EV71 infections, although its source remained a mystery. Gene sequencing tests showed the strain of EV71 isolated from the boy was a 'relative' of that found in Malaysia in 1997 and Taiwan last year. However, Dr Mak Kwok-hang, the department's consultant in community medicine, said the public should not be alarmed. He said the strain was only similar to 'one of the many' discovered in Taiwan and Malaysia. It was different to the strain found in Hong Kong last year. 'There is no evidence to show that the gene sequence of enterovirus is directly linked to its toxicity,' he said. More than 30 children in Malaysia and 50 in Taiwan died after suffering hand-foot-mouth disease, one of the manifestations of EV71. However, health authorities are still unable to prove the epidemic was caused by EV71. The Hong Kong boy died on May 14 after 10 hours in intensive care at Kwong Wah Hospital. It was the first fatal case reported in the territory since the surveillance system on hand-foot-mouth disease was set up last June. The boy's sister made a full recovery. Dr Mak said good personal hygiene remained the best prevention. The Hospital Authority's taskforce on enterovirus infection met yesterday and agreed to improve surveillance of hand-foot-mouth disease in public hospitals.