Mar 14, 2005 (CIDRAP News) – A second Vietnamese nurse who had cared for an avian influenza patient was reported to have a suspected case of the illness 2 days ago, but a Vietnamese newspaper said today that the nurse is free of the virus.

The nurse, a 41-year-old woman from Thai Binh province, was hospitalized in Hanoi Mar 10 with a high fever, cough, and a lung infection, according to a Mar 12 Associated Press (AP) report.

But an online report by Than Nien News today said the nurse tested negative for avian flu at the Center for Tropical Diseases in Hanoi. Vietnam"e;s Central Institution of Sanitation and Epidemiology reported the test results yesterday, the story said.

The AP said the nurse had cared for a 21-year-old Thai Binh man who remains in critical condition with avian flu. Last week a 26-year-old male nurse who had helped care for the same man was reported to have the illness. He is the first healthcare worker known to have contracted the disease, though health officials said he probably acquired the virus from poultry rather than from his patient.

The 21-year-old patient is part of a family cluster of cases that includes his 14-year-old sister and 80-year-old grandfather. The grandfather tested positive for the virus but was asympotmatic, according to reports last week.

The Than Nien News report gave no details on the condition of the 41-year-old nurse.

The story said Vietnamese health officials are doing "extensive research" on how the virus has spread in Thai Binh, where at least eight cases have occurred since the beginning of this year.

The recent cases in Thai Binh include two asymptomatic ones, that of the 80-year-old man and that of a 61-year-old woman whose husband died of avian flu Feb 23.

Today Peter Horby, a World Health Organization epidemiologist in Hanoi, issued a clarification about a statement attributed to him in a Reuters report on the asymptomatic cases last week.

A Mar 10 story had quoted Horby as saying, "There is no evidence that asymptomatic infection like this poses any significant risk of onward transmission, so it is not alarming in that sense."

In the clarification, posted on ProMED-Mail, Horby said the statement referred specifically to the experience with the H5N1 virus in Hong Kong in 1997, "where there was no evidence of onward transmission from asymptomatic or mildly symptomatic H5N1 cases."

Horby said his office is advising that asymptomatic patients be placed in isolation or home quarantine and treated with the antiviral drug oseltamivir. In addition, he said authorities should search for evidence of asymptomatic or mildly symptomatic cases among their contacts.