Analysis of first cluster outbreak of the pandemic influenza (H1N1) in Georgia

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Background: On 30 July, 2009 a member of a Georgian dance group was confirmed to have influenza A(H1N1). For that time 7 sporadic imported cases of influenza A(H1N1) have been confirmed in Georgia. Group had just returned from touring Western Europe. We investigated transmission of influenza within the group and their close contacts upon return to Georgia.

Methods: WHO case definitions of pandemic influenza A(H1N1) virus based on real-time RTPCR confirmation were used. We collected information regarding age, symptoms, and health practices using a standardized questionnaire. Received data have been analyzed in EpiInfo

Results: As of 17 August 2009, we detected 5 confirmed and 9 probable case-patients with influenza A(H1N1) virus (13 of 35 group members, Attack Rate=37%; 1 of 37 in-country contacts, AR=3%). First probable case developed symptoms on 20 July, 2009 during the tour. All the subsequent a case have developed symptoms within the possible period of a transmission of infection from previous cases. Age distribution of cases was 10 to 18 years old; none of 30 adults (4 group members and 26 in-country contacts) was affected. Common symptoms of case-patients were: fever over 380C (70%), cough (35%), sore throat (35%), runny nose (35%) and, headache (29%). 93% of all cases revealed limited hand-washing during the tour and all of them had been in close contact with each other for 5 days while traveling by ferry and bus. No group members or contacts were ever vaccinated against seasonal influenza. No one received antiviral treatment. No complications or deaths have occurred.

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Epidemiological curve of date of symptoms onset in cluster outbreak of pandemic influenza (H1N1), July-August 2009, Georgia

Conclusion: First cluster outbreak in Georgia coincided with summer pick of pandemic influenza A(H1N1) virus in the Western Europe. Investigations showed that more susceptible were under 18 years’ old group members and no transmission was identified in adults. Poor hygiene and close contact were the most likely risk factors of transmission among the group. Discontinuation of these conditions after arrival and moderate severity of the disease may explain limited in-country transmission, as evidenced by the differences between the attack rates among group members and in-country contacts. These findings suggest that social distancing and appropriate hand hygiene could have an important role in reducing transmission of A(H1N1) virus.