Bird flu outbreaks that have killed seven people in several countries so far this year show the virus remains a threat to humans, the World Health Organization (WHO) said on March 24.
"The newly confirmed human and poultry cases of avian influenza this year are a reminder that the virus poses a real and continuous threat to human health," the WHO said in a statement.
One danger is that bird flu, also known as H5N1, may mutate, warned Takeshia Sakai, the WHO's regional adviser for communicable diseases.
"The influenza virus is unpredictable," Sakai said. "There is a constant risk that the H5N1 virus will combine with another strain of influenza."
So far this year, authorities monitored 21 human cases of bird flu from Egypt, Vietnam and
Indonesia, including seven deaths, the organization said.
There have also been reports of outbreaks of the virus in poultry and wild flocks in other parts of Southeast Asia, as well as in Bangladesh, Bhutan, India, Israel and Nepal, it said.
In a recent case, a three-year-old girl infected with the influenza A (H5N1) virus, died in Ho Chi Minh City on March 17, bringing the country's avian flu death toll to 59 since 2003.
The child, whose name has not been released, was admitted to Children's Hospital No. 2 with symptoms of dengue fever but later developed pneumonia. She had tested positive for bird flu two days earlier.
Doctors said her family lived in a rented house nearby a market where chickens were sold in the adjacent province of Binh Duong's Thuan An District.
It was the second H5N1-related death recorded in Vietnam this year, with the first reported last month.
Since 2003, 116 people have been infected by bird flu in Vietnam, including five this year.
Vietnam recorded five avian flu patients last year, all of whom died.
Human cases of bird flu peaked in 2006 at 115, with 79 deaths. The number has since declined, with 73 human cases and 32 deaths in 2009, the WHO said.
However, the fatality rate for humans infected with bird flu remains high at 59 percent, it added.
Though bird flu has recurred in Vietnam and claimed two deaths this year, the sale of live chickens and other fowl that have not been quarantined and tested is still popular.
Authorities have not been taking many preventive measures against the illegal trade, say market observers.
The illegal poultry trade can be easily seen happening in many Ho Chi Minh City locations, especially in outlying districts like Go Vap, Hoc Mon, and District 12.
Along a 200-meter stretch of the Tan Son Street which passes through Go Vap and Tan Binh districts, Thanh Nien found nearly 20 hotspots where live and untested chicken were being sold for VND80,000-VND90,000 per kilogram. Ducks were cheaper, costing VND45,000-VND60,000 per kilogram.