Recombinomics: Toddler to Toddler H5N1 Transmission in Beheira Egypt

Commentary

Recombinomics Commentary 18:29
April 7, 2009

Boy, age 2, began experiencing fever and cough symptoms on March 27.
Boy, age 2, began experiencing fever, cough and runny nose on March 31.

The above comments describe the two most recently H5N1 confirmed toddlers in Egypt. These two cases were next door neighbors in the Kom Hamada district of Beheira and represent toddler to toddler transmission of H5N1. This cluster follows a spate of toddler cases in Egypt this year. 10 of the 12 confirmed cases have been toddlers and 9 of the 10 toddler cases have been mild. Both patients above are described as being in "good general condition" and will likely be discharged soon. None of the H5N1 cases this year in Egypt have died, which is similar to the mild cases of H5N1 in Egypt in the spring of 2007. However, unlike earlier cases, which included 6 toddlers over a three year period, the percentage of toddler cases has dramatically increased in 2009.

Although the two cases above are said to have had contact with dead or sick poultry, the confirmation of neighboring cases who developed symptoms four days apart is unlikely to be due to two independent poultry infections. There have been no confirmed poultry cases in the Kom Hamada area. Since March 1 there were 24 confirmed H5N1 poultry outbreaks in Egypt, and although 7 were in Beheira, these outbreaks were well to the north and not near the toddler cluster (see updated map). Over 60 outbreaks have been confirmed this season, and none were close to Kom Hamada. Similarly, the toddler case preceding the cluster was in Qena, and there have been no confirmed poultry outbreaks in Qena this season (see updated map).

Although there are clearly more H5N1 outbreaks than those confirmed, the targeting of toddlers raises concerns that old age groups have developed protective immunity, signaling a significant silent spread of H5N1 in Egypt. Over 6000 patients with poultry links have been hospitalized, but less than 1% have tested positive. However, it remains unclear if the low confirmation rate is due to an aggressive testing program, or a lack of sensitivity in the testing.

Confirmed H5N1 clusters have been rare in Egypt have been rare. The largest was the Ghabiya cluster at the end of 2006, but the prior clusters were among relatives and did not have the gap in disease onset dates. The Beheira cluster has the classical gap and there has been no indication that the two toddlers were related. Although it is likely that mild H5N1 has was transmitted human to human, based on the sequence identity between isolates from unrelated cases, the current cluster has the time and space signature associated with human to human transmission.

Sequences from this cluster, as well as testing of toddlers that have symptoms but lack a poultry link would be useful.
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