Grandfather Expands Thai Binh Bird Flu Cluster to Four
Recombinomics Commentary
March 9, 2005
>> Health authorities suspect a meal of goose the family had on February 8 was the source of the infections. However, they ate chickens and geese several times during the week-long Lunar New Year festival last month.
Several cases in Vietnam and Thailand have involved family clusters, with several relatives were infected at the same time, though there has been no evidence that the virus has mutated into a form easily transmitted by people. Health officials warn that when that happens, the virus could spark a global pandemic that kills millions. <<
Detection of H5N1 in the grandfather (81M) of the two Thai Binh siblings increases the size of the contact cluster to four, clearly demonstrating human-to-human transmission over several generations. Since the grandson (21M) developed symptoms February 14, the granddaughter (14F) developed symptoms February 21, and the nurse developed symptoms on or about February 26, the human-to-human transmission has gone through several generations.
This cluster is similar to the Thai Binh cluster in January, where disease onset dates were over an extended time period and one asymptomatic family member was reported. In that familial cluster, the index case (45M) developed symptoms December 26, 2004. His middle brother (42M) developed symptoms January 9, and the youngest brother (36M) was H5N1 positive according to media reports. However, there was no confirmation, and like the grandfather described above, he did not develop symptoms nor did he eat the blood duck pudding. Similarly, media reports on the most recent cluster indicated that three siblings ate blood duck pudding. Only two developed symptoms and only the three siblings ate the pudding.
More details on the test on the grandfather would be of interest because H5N1 has been reported in Hanoi live markets since 2001, so antibody levels against H5N1 may not be due to recent infections. The multimodal disease onset dates clearly point toward multiple generations of H5N1 transmission, and virtually eliminate common sources such as meals.
H5N1 positive results in asymptomatic patients suggest widespread human-to-human transmission in Thai Binh, as the number of confirmed infected patients from the area continues to grow.
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