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.
Study puts Vietnam in H7N9 crosshairs
In the mapping 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.
China, Hong Kong report new cases
The new H7N9 cases include a new imported case that health officials in Hong Kong are investigating, according to a statement today from the Hong Kong Centre for Health Protection (CHP). The patient is a 5-month-old baby girl who lives in the Guangdong city of Foshan on the mainland, but had been staying in Shenzhen for the past week.
When she started having a fever and vomiting yesterday, her parents brought her to Hong Kong in the evening, where she was evaluated at an area hospital, according to the CHP. Her respiratory samples tested positive for the H7N9 virus today, and she is isolated in stable condition at Hong Kong's Princess Margaret Hospital.
The CHP said an initial investigation into the source of the girl's illness found that her grandparents had taken her to a live-poultry market in Shenzhen 4 or 5 days ago, but that she did not have direct contact with the birds.
Her illness is the seventh imported case to be detected in Hong Kong.
The other case-patient also has ties to Guangdong province, one of the main hot spots of human infections in the second wave, as well as a source of infected poultry, including imported shipments that tested positive for the virus outside of the mainland in Hong Kong and Macau. The second wave began in October.
Announced by the province's health department yesterday, the patient is a 71-year-old woman who is listed in stable condition in a Shenzhen hospital, according to a statement translated and posted by FluTrackers, an infectious disease news message board.
The two infections edge the outbreak's overall total to 394, according to a human case list compiled by FluTrackers. The unofficial number of deaths remains at 120.
Mar 15 J Infect abstract
Mar 17 CHP statement
Mar 16 FluTrackers thread
FluTrackers human H7N9 case list