Commentary
Remarkable
H5N1 Demographic in Egypt
Recombinomics Commentary
15:44
April 5, 2009
The other case was a 2-year-old boy from Ganain District, Suez Governorate, who first showed symptoms suumbleble to HPAI H5N1 infection on 2 February and was admitted to the hospital the next day. He is now in stable condition.
Remarkably, all 4 cases of HPAI H5N1 influenza recorded so far this year have been children between 1-2 years of age. The total number of HPAI H5N1 infected people in Egypt by the end of February 2009 reached 55 of which 23 died.
The above comments are from the official report on H5N1 in Egypt in February, which qualifies the fact that all four cases in 2009 were toddlers, with "Remarkably". However, this characterization has now moved into the "Alarmingly" category, since four of the five cases in March were toddlers, as were the two Beheira cases last week bring the 2009 total to 10/11 (see updated map). Moreover, 10/11 cases this year were mild, and all 11 have recovered or are likely to recover, since there is no hint of pneumonia or requirements for respirators in any cases from the last month.
Although the reduction of the case fatality rate for 2009 to zero may seem to be a positive, the fact that almost all cases were toddlers raises concerns that protective immunity is reducing viral loads in older patients to the undetectable level. Media reports continue to describe large numbers of patients hospitalized with symptoms, and these hospitalized patients represent a wide age range, which includes many familial clusters. Historically, less than 1% of hospitalized suspect patients test PCR positive for H5N1, which raises concerns that many cases have viral loads below the detection limit, and now the detection rate for these older populations has fallen from 1% of cases to 0% of cases.
Protective immunity could be due to prior exposure to H5N1 or cross protection from seasonal flu, which would be most likely from H1N1. However, the large number of cases in toddlers, which have previously been limited to 1-3 cases per year, raises concerns that the efficiency of human infections has increased, but is only reflected in the toddler data.
If the efficiency has increased, or if the absence of older cases is due to protective immunity from H5N1, then there should be H5N1 positive toddlers who lack a poultry link, or there should be detectable levels of H5N1 antibodies in the older patients.
The alarming concentration of mild H5N1 confirmed cases in toddlers in 2009, requires a significant expansion of testing to address the above concerns. These concerns have increased because local media reports are now describing the two Beheira toddlers as neighbors.
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