At least five members of an Indonesian family have been infected with bird flu, the World Health Organization confirmed on Wednesday, after the case triggered widespread fears of human-to-human transmission.
There is no immediate evidence the H5N1 flu virus passed easily among at least seven members of the family in North Sumatra province. But experts said on Wednesday nothing could be ruled out and more testing was crucial.
In a day of fast-moving events, the WHO also said a caterer from Surabaya city in East Java had died of bird flu, while Indonesia’s health ministry said local tests had confirmed a 12-year-old boy from Jakarta who died four days ago was infected with H5N1. Both cases are separate from the Sumatra case.
Clusters of human infections are worrying because they indicate that the virus might be mutating into a form that is easily transmissible among humans. That, experts say, could spark a pandemic in which millions might die.
For the moment, the virus is mainly a disease in birds and is hard for humans to catch.
The WHO and other health experts are puzzled over the source of infection in the Sumatran family, six of whom have died.
“The possibility that they may have been infected by the same source is still there,” said Sari Setiogi, the WHO spokeswoman in Indonesia. More animal samples would be collected for testing.
“Any time we have a cluster, it raises the suspicion that human-to-human transmission may have occurred. We don’t rule out either way ... it is too early to make any conclusion because investigations are still going on,” Setiogi said.
The WHO has sent a team to Kubu Simbelang village in Karo regency, about 50 km (30 miles) south of Medan.
Samples taken from six members of the family were sent to a WHO-affiliated laboratory in Hong Kong and five tested positive for H5N1. Results of the sixth were still pending.
Samples from the first person to fall ill, a 37-year-old woman, were not sent to Hong Kong but she is considered to have been infected with H5N1. She fell ill on April 27 and later died.
No suggestion of mutation
Asked about the possibility of a change in the virus and whether there had been human-to-human infection in Sumatra, a WHO spokeswoman in Geneva said, “It is too early to draw any conclusions.
“I have not heard any suggestion that the virus is any different,” Maria Cheng said, referring to the laboratory tests in Hong Kong.
Indonesia’s Health Ministry said the Sumatra cluster was not a case of human-to-human transmission.
“The spread was through risk factors from poultry or other animals. There is no proof of human-to-human,” Nyoman Kandun, director-general of disease control, told Reuters.
But an Indonesian agriculture official who declined to be identified said animal tests have not shed any light.
“There is a big question mark. Blood samples from all kinds of animals from chickens, ducks, geese, birds, pigs, cats and dogs turned out negative so far. Manure has also been checked. The result is negative,” the Jakarta-based official said.
Hong Kong virologist Guan Yi said the long time lag of nine days between the first and last victims showing symptoms of the disease was unusual.
“If they were all infected by the same source, their onset time (of illness) would have been closer, but that is not the case ... The later cases may involve the possibility of human-to-human transmission,” Guan told Reuters.
“They may have infected one another ... but we have no evidence. This needs to be investigated by the locals.”
The latest deaths bring to at least 30 the number of people killed by bird flu in Indonesia, more than half since the start of the year.
Among the confirmed deaths on Wednesday was a 38-year-old catering businesswoman from Surabaya who had dealt with live pigs and pork meat before she died last week.
Not including the latest cases, bird flu has killed 115 people worldwide, the majority in east Asia, since reappearing in 2003. Virtually all the victims caught the disease from poultry.
The U.N. Food and Agriculture Organization said on Wednesday that H5N1 had been found in a duck in Laos, but there was no sign the virus was spreading.
On Tuesday, a senior Indonesian Agriculture Ministry official said the virus had been detected for the first time in poultry in remote eastern Papua province.