Human To Human Transmission Of Bird Flu

Tests
indicate that a father diagnosed with bird flu in China probably caught
the disease from his son, only increasing concern about transmission of
the virus between humans. This was published early online and in the
April 2008 issue of The Lancet.



As of April 2, 2008,
there have been 376 cases of infection with the highly pathogenic avian
influenza A (H5N1) virus with 238 deaths reported in 14 different
countries since November 2003. While most cases have been scattered,
about one quarter of all cases have been in clusters of two or more
people.



These two men, diagnosed within a week of one another,
were investigated by Professor Yu Wang, Chinese Centre for Disease
Control and Prevention, Beijing, China, and colleagues in December 2007
in China's Jiangsu Province. Both laboratory and field tests were
performed immediately to determine a positive H5N1 infection in both
cases. Additionally, 91 people with whom they had come into
close
exposure, and more removed contacts who became at all ill were tested.



The
son, aged 24, died, while his 52 year old father survived after
receiving early antiviral treatment and post-vaccination plasma from a
participant in an H5N1 vaccine trial. The only potential point of
exposure of the son's was a visit to a poultry market six days before
the illness's onset. In the meanwhile, the father had considerable
unprotected exposure to his sick son.



All 91 exposed contacts
gave consent for examination -- of these, 78 were administered
anti-retroviral prophylaxis and two suffered from mild illness.
However, all 91 tested negative for H5N1. The viruses isolated from
father and son were genetically identical with the exception of one
small base change in the nucleic acid chain making up the H5N1 genetic
structure.



The authors conclude that the transmission
was probably between the two men. "Limited, non-sustained
person-to-person transmission of H5N1 virus probably occurred in this
family cluster...Viral characteristics required for sustained
person-to-person transmission remain unknown. H5N1 clusters require
urgent investigation because of the possibility that a change in the
epidemiology of H5N1 cases could indicate that H5N1 viruses have
acquired the ability to spread more easily among people."



Dr
Jeremy Farrar, Hospital for Tropical Diseases, Ho Chi minh City,
Vietnam, and colleagues, wrote an accompanying comment, in which they
say: "Whatever the underlying determinants, if we continue to
experience widespread, uncontrolled outbreaks of H5N1 in poultry, the
appearance of strains well adapted to human beings might just be matter
of time. In the meantime, all family contacts of a patient with
probable or confirmed H5N1 should be given chemoprophylaxis and placed
under surveillance. Personal protection and advice must be extended to
the family members and health workers visiting and looking after
patients in hospital."



"Today's study is a superb piece of
work showing the benefit of a longstanding and trusting international
collaboration that began during the severe acute respiratory syndrome
epidemic. Such collaborations sustained over several years, centred in
affected countries, and closely linked with WHO are our best chance of
combating current and future threats to international health and
ensuring that benefits are shared worldwide."



Probable limited person-to-person transmission of highly
pathogenic avian influenza A (H5N1) virus in China

Hua
Wang, Zijian Feng, Yuelong Shu, Hongjie Yu, Lei Zhou, Rongqiang Zu,
Yang Huai, Jie Dong, Changjun Bao, Leying Wen, Hong Wang, Peng Yang,
Wei Zhao, Libo Dong, Minghao Zhou, Qiaohong Liao, Haitao Yang, Min
Wang, Xiaojun Lu, Zhiyang Shi, Wei Wang, Ling Gu, Fengcai Zhu, Qun Li,
Weidong Yin, Weizhong Yang, Dexin Li, Timothy M Uyeki, Yu Wang

The Lancet, April 8, 2008

DOI:10.1016/S0140-6736(08)60493-6

Click Here For Journal



Person-to-person transmission of influenza A (H5N1)

Nguyen Tran Hien, Jeremy Farrar, Peter Horby

The Lancet, April 8, 2008

DOI:10.1016/S0140-6736(08)60494-8

Click Here For Journal



Written by Anna Sophia McKenney