27 January 2005 With the number of human bird flu cases in Viet Nam since mid-December now reaching 10, nine of them fatal, the United Nations health agency has warned that further sporadic cases and occasional family clusters can be expected considering the current spread of outbreaks in poultry in some Asian countries.
Experience to date indicates that possible human-to-human transmission has occurred mainly during prolonged close contact of a family member with a patient who was critically ill with the H5 virus subtype, which earlier last year infected 45 people, 32 of them fatally, and resulted in the deaths or culling of more than 100 million birds, the World Health Organization (WHO) said.
WHO has warned several times over the past year of the potential evolution of the virus into a human pandemic which, in a worst-case scenario, could have devastatingly deadly consequences.
The agency said Viet Nam’s Health Ministry yesterday reported the two latest laboratory confirmed cases, both fatal, in the southern part of the country.
A family cluster of three brothers, two of whom died, in northern Viet Nam has been the focus of intense investigation. The source of infection of the two who died remains undetermined, while the third, who provided bedside care for his brothers, was hospitalized with respiratory symptoms and has now fully recovered.
Surveillance for further cases among health care workers, other family members and residents in both communities where the brothers lived has so far found no evidence of additional cases. If limited human-to-human transmission has occurred, all evidence at this stage suggests that the chain of transmission ended after a single person was infected, WHO said.
The agency has already warned that cooler winter temperatures and activities linked to the approach of the Lunar New Year in February may increase the risk of further human cases.
Last year it voiced concern several times that continuing transmission of the virus to humans might give avian and influenza viruses an opportunity to exchange genes, potentially giving rise to a new human virus with pandemic potential. The so-called Spanish flu pandemic of 1918-20 is estimated to have killed 20 million people worldwide.