Kratie Province – Credit Wikipedia
# 8311
A week ago (see Cambodia: 2 Deaths - 1 Confirmed H5N1, 1 Probable) we learned of the deaths of two siblings (ages 2 & 8) on the same day at a hospital in Kratie Province, Cambodia. While both children were hospitalized with similar symptoms, and both died within hours of each other, only one was confirmed to have been infected with the H5N1 virus.
No samples were tested from the younger sibling to confirm H5N1, making her a probable, not a confirmed case.
Today Cambodia’s MOH is reporting the detection of another H5N1 infection in a child from the same location (Kbal Trach village, Sre Cha commune, Snourl district) – apparently discovered by the surveillance team sent to the village to investigate the outbreak. The child – a four-year-old who was hospitalized last Thursday and confirmed H5N1 positive last Friday – is described as being in stable condition with `mild’ symptoms.
First excerpts from the MOH announcement, after which I’ll return with a bit more.
3rd New Human Case of Avian Influenza H5N1 in Cambodia in 2014
Joint Press Release From the Ministry of Health, Kingdom of Cambodia, and the World Health Organization (WHO)
Phnom Penh, 19 February 2014
The Ministry of Health (MoH) of the Kingdom of Cambodia wishes to advise members of the public that one new human case of avian influenza has been confirmed for the H5N1 virus. This is the 3rd case this year and the 50th person to become infected with the H5N1 virus in Cambodia. The case is from Kratie province. Of the 50 confirmed cases, 38 were children under 14, and 27 of the 50 were female. In addition, since the first case happened in Cambodia in 2005 there were only 16 cases survived.
A 4-year-old boy from Kbal Trach village, Sre Cha commune, Snourl district, Kratie province, was confirmed positive by Institut Pasteur du Cambodge (IPC), on 14th February 2014. The boy had onset fever and vomiting on 8th February 2014. The boy was detected by the mobile surveillance team during contact tracing of the 2nd confirmed case on 12th February. His symptoms were fever, running nose, vomiting, sore throat and cough. He was admitted to Kratie Provincial Hospital on 13th February and Tamiflu was administered on the same day. The symptoms were mild and the boy is now in good condition.
The case had direct exposure with dead and sick poultry. The boy played and carried dead chicken 6 days before developing symptoms. Around mid-January, a high number of poultry (chicken, ducks and goose) started to die in the village (around 350). Animal Health officers took samples from sick/dead chickens on 9th February and tested negative for H5N1 by National Veterinary Research Institute (NAVRI).
While discovered during contract tracing with that village’s previously confirmed case, this young boy also shared environmental contact with dead or dying birds in the area, making it impossible to say with absolute certainty how he contracted the virus.
Given the limited history of human transmission of the H5N1 virus, acquisition from infected poultry is the better bet, however.
The described `mild’ presentation of the virus - fever, running nose, vomiting, sore throat and cough – raises concerns that had a the surveillance team not been dispatched, this case might never have been identified. As with almost any illness, only the `sickest of the sick’ end up hospitalized and positively diagnosed, meaning that the case numbers we have are almost certainly a sub-set of the total disease burden.
While there has been much debate over the `true’ number of H5N1 human infections, and the truth is, nobody really knows.
The limited number of seroprevalence studies that have been done to date have returned mixed results, although most have shown low levels of seropositivity in the general population, and only slightly elevated in poultry workers (see PLoS One: Seroprevalence Of H5N1 Among Bangladeshi Poultry Workers for an overview).
Despite seeing a second (and if you count the untested sibling, third) case from the same village, the sporadic nature and broad geographic distribution of Cambodia’s recent H5N1 cases show no evidence of community-level transmission, and the assumption is that these infections came from exposure to infected birds.
The World Health Organization’s most recent public health assessment on the H5N1 virus reads:
Overall public health risk assessment for avian influenza A(H5N1) viruses: Whenever influenza viruses are circulating in poultry, sporadic infections or small clusters of human cases are possible, especially in people exposed to infected household poultry or contaminated environments. This influenza A(H5N1) virus does not currently appear to transmit easily among people. As such, the risk of community-level spread of this virus remains low.
Viruses change over time, and so could this assessment.
Which is why we watch these cases carefully, looking for any signs that the virus has better adapted to human physiology.
