Chinese health authorities today reported two more novel H7N9 infections from different parts of the country, including in a 3-year-old boy with mild illness who is hospitalized, according to media reports and an early notification from the World Health Organization (WHO).
The cases are the third and fourth to be reported since the middle of October and would boost China's number of H7N9 infections to 139, which includes 45 deaths.
First case in Guangdong
The boy is hospitalized in Dongguan City in southern China's Guangdong province, where he is in stable condition, Xinhua, China's state news agency reported today. His infection was detected during routine hospital monitoring of flulike cases.
Donnguan is a large industrial city that borders Guangzhou, the provincial capital. The youngster's illness is Guangdong's second H7N9 case. The province's first case was reported in early August, months after the virus was detected in poultry markets there.
Hong Kong's Centre for Health Protection (CHP) said in a statement that the boy doesn't have a fever and his flu-like symptoms are minor. All seven of the boy's close contacts who were under close observation tested negative for the virus, though three had flu-like symptoms.
Second case in Zhejiang
Very few details were available about the second case-patient, who is from Zhejiang province. The first news of the detection came from WHO Twitter posts, which said China had notified it of two new lab-confirmed H7N9 cases in Guangdong and Zhejiang.
Gregory Hartl, a WHO spokesman, said in separate Twitter posts that the two H7N9 cases were reported from different parts of China on the same day. "Winter is starting," he said.
In October Zhejiang province, located roughly 800 miles northeast of Guangdong, reported two H7N9 cases, in a 35-year-old man who was hospitalized in critical condition and in a 67-year-old farmer who had contact with live poultry and was also listed in critical condition.
Zhejiang is the Chinese province with the most H7N9 cases, with 49 infections and 11 deaths reported so far.
Wave of infections coming?
When the H7N9 virus was first detected China in March, the number of cases soared, then dropped sharply in May, with only two additional cases reported over the summer. Global health officials said poultry-market closures probably played a role in the declining number of cases, and there was a chance that the virus could burn itself out.
They said, however, that they expected sporadic cases to continue. And they warned that although flu viruses are unpredictable, there was a chance that the number of cases could start rising again as the Northern Hemisphere's weather cools, a pattern seen with other avian influenza viruses such as H5N1.
The four H7N9 infections reported in China so far this fall are fueling speculation that the events could herald another wave of infections with the new virus, but some influenza experts say it's too soon to tell.
Richard Webby, PhD, director of the WHO collaborating center for influenza studies at St. Jude Children's Research Hospital in Memphis, told CIDRAP News that it's a bit early to say if the increased H7N9 activity is due to cooling conditions, "or if we are seeing an increase at all." He added, "Chicken production is also likely getting ramped up soon for Chinese New Year."
Marion Koopmans, DVM, PhD, head of virology at the Laboratory for Infectious Diseases of the National Institute of Public Health and the Environment in the Netherlands, said the timing of the cases gives a hint of seasonality, but she said so far there are too few of them and that it's too early to say they signify a trend.
She said it would be useful to see some information from periodic market surveys to assess possible trends. "Whether or not we expect seasonality is related to the question where these viruses come from," Koopmans said, adding that H5 seasonality reports seem to come mainly from behavior of the virus in wild birds. "If H7N9 is circulating in backyard farms, the picture may be quite different."
Poultry are strongly suspected at the source of the new virus, and the WHO has warned that since H7N9 causes only subclinical infection in the birds, it could still be circulating in China and perhaps its neighbors. It has urged China and bordering countries to continue vigilance for the virus.
Nov 5 Xinhua story
Nov 5 CHP statement
WHO Twitter feed
Gregory Hartl Twitter feed
Oct 15 CIDRAP News story "Chinese man hospitalized with severe H7N9 flu"
Oct 23 CIDRAP News scan "WHO confirms H7N9 case in China"