Study says Vietnam at H7N9 risk as two new cases noted
A mapping study in China that recently predicted the spread of the H7N9 avian flu virus into Guangxi province has flagged northern Vietnam as the next high-risk area, according to researchers in China and their US collaborators.
The findings come at a time when the pace of new H7N9 cases in the second wave of infections has slowed to just a few sporadic cases per week. Two cases were reported in the past 2 days—one from Hong Kong and the other from China’s Guangdong province.
In the study, researchers plotted the locations of H7N9 cases and negative cases from China’s flulike illness surveillance. They identified H7N9 risk factors with logistic regression, and used geographic information systems (GIS) to make maps that predicted H7N9 risk across Asia. The team published its findings on Mar 15 in the Journal of Infection.
The same method using H7N9 cases reported in the spring wave of cases last year predicted that the virus would spread to Guangxi province, an area that borders northern Vietnam, in February 2014. In late January and early February, three human cases were reported from the province, including one involving a 5-year-old boy who got sick after an H7N9 infection was detected in his 41-year-old mother. The province’s other patient is a 56-year-old woman who in late January was reported as its first case-patient.
Researchers noted that even though the map was constructed using cases reported during the spring wave, it was able to predict patterns during the second wave.
In looking at potential spread outside China, the model predicts a high risk of H7N9 infections in humans in northern Vietnam, according to the report. The team noted that Guangdong province, a hot spot for human and poultry infections, is within 200 kilometers (125 miles) of the Vietnamese border.
The findings add support to the need for increased surveillance in northern Vietnam for human illnesses and positive samples from live-poultry market, the team wrote. They added that each day northern Vietnam’s Quang Ninh and Lang Son provinces import 100 tons of hens from China that are past their egg-laying peak and are sold for meat.
Other possible sites in Southeast Asia flagged by the model include northern Laos and eastern Myanmar, but the researchers noted that those nations aren’t known to import chickens from areas of China in which H7N9 has been reported.