Surveillance on the 2009 pandemic influenza A (H1N1) virus, Isfahan, Iran

During the spring of 2009, a new influenza A (H1N1) virus caused human acute respiratory illness first in Mexico.1 The Iranian Ministry of Health (MoH) launched a system to monitor and report the presence of this new virus throughout the country on May 10, 2009. Here we report the first confirmed cases of influenza A (H1N1) virus that were identified from July through October 2009 in Isfahan, the second important province in Iran. In a laboratory-based reporting system, the Provincial Health Centers were supplied by the MoH with case definition and patient information forms to be disseminated to all health care institutions in their province. Any person who fulfilled the case definition criteria 2 was directed to designated health facilities. The nasopharyngeal samples were sent to the National Influenza Reference Laboratory at Tehran school of Public Health in a viral transport medium (virocult, Medical wire & Equipment, UK) and were tested with the real time RT-PCR protocol and reagents supplied by the WHO. A total of 376 samples were taken from suspected cases. Fifty from these samples were positive. The first confirmed case had traveled to Mecca (Saudi Arabia) and had already become symptomatic while staying there. The median age was 27 years (range: 10-75 years). Most travel-associated cases were returning travelers from Saudi Arabia (55.2%); followed by Malaysia (17.24%). Fever was the most common symptom, presented in 95.9% of the cases, followed by cough (85.7%) and myalgia (77.5%). Influenza A (H1N1) virus entered Isfahan through travelers, mainly coming from Saudi Arabia.3 The majority of the confirmed cases consisted of young adults and they mainly manifested clinical symptoms similar to those reported in other areas.4 Since many patients with influenza like symptoms may not visit the physicians, it is possible that the cases have been under diagnosed.