Avian influenza virus H7N9 in stool

Bird flu virus H7N9 detected in stool samples

08/16/2013

Since the first evidence of an infection with the deadly avian influenza virus H7N9 in China at the end of March, 45 people have died from the novel pathogen, according to Chinese health officials. A total of 134 cases of H7N9 infection in mainland China have been confirmed to date, said National Health Director Yu Wang. Despite intensive research, there is „many more unknown aspects of the H7N9 bird flu virus, including the source of the virus, the routes of infection and mutation“,Wang Yu continued. In a recent study, scientists around Yuen Kwok-Yun of the University of Hong Kong have now shown that the pathogens are also detectable in stool samples of patients and could possibly be passed on from person to person in this way.

Although it has long been suspected that a human-to-human transmission of H7N9 viruses is possible, so far there is no evidence for an interpersonal transmission of the pathogens. The research team around microbiologist Yuen Kwok-Yung has now published in the journal „Clinical Infectious Diseases“ published a study proving that stool samples may also contain the H7N9 virus to the infected. The researchers studied stool, urine and blood samples as well as sputum and a swab of the nasopharyngeal mucosa of twelve patients who needed to be treated for the influenza virus infection in the intensive care unit. Six of the patients had died as a result of the infection. They also performed a post-mortem biopsy of the lung, liver, kidney, spleen, bone marrow and heart.

More than two-thirds of stool samples are burdened with H7N9 viruses
The researchers made some surprising findings in the course of their investigations. For example, in four of the six stool samples (67 percent) of the deceased, the H7N9 virus was detectable. Also in the chair of two survivors (33 percent), the pathogens were detected. In addition, a significantly higher viral load was seen in the sputum (sputum) of the infected than in the swab directly from the nasopharyngeal mucosa. However, the tests of urine, blood and cerebrospinal fluid were negative. No bird flu viruses were detected here. Whether an interpersonal transmission of the pathogen over the sputum or contaminated chair is possible, must now be checked in further studies. The Director of the Chinese Health Authority concludes that „in particular, the future development of the new bird flu virus is still unclear“ be. Here, the risks of an influenza pandemic should not be underestimated, Wang said. The study director Yuen Kwok-Yung also sees the risk of a renewed increase in infections in the winter of this year. (Fp)

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Worrying experiments with bird flu viruses

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