Methods. A cross-sectional survey was conducted among pilgrims as they arrived at the King Abdulaziz International Airport in Jeddah for the 2009 Hajj and as they departed from the same airport during the week after the Hajj. Nasopharyngeal and throat swabs were tested

for 18 respiratory virus types and subtypes using the xTAG Respiratory Viral Panel FAST assay. Results. A total of 519 arriving pilgrims and 2,699 departing pilgrims were examined. Their mean age was 49 years and 58% were male. In all, 30% of pilgrims stated that they had received pandemic influenza A(H1N1) vaccine before leaving for the Hajj Raf inhibitor and 35% of arriving pilgrims reported wearing a face mask. Only 50% of arriving

pilgrims were aware of click here preventive measures such as hand hygiene and wearing a mask. The prevalence of any respiratory-virus infection was 14.5% (12.5% among arriving pilgrims and 14.8% among departing pilgrims). The main viruses detected (both groups combined) were rhinovirus-enterovirus (N = 414, 12.9%), coronaviruses (N = 27, 0.8%), respiratory syncytial virus (N = 8, 0.2%), and influenza A virus (N = 8, 0.2%) including pandemic influenza A(H1N1) (N = 3, 0.1%). The prevalence of pandemic influenza A(H1N1) was 0.2% (N = 1) among arriving pilgrims and 0.1% (N = 2) among departing pilgrims. The prevalence of any respiratory virus infection was lower among those who said they received H1N1 vaccine compared to those who said they did not receive it (11.8% vs 15.6%, respectively, p = 0.009). Conclusion. We found very low pandemic influenza A(H1N1) prevalence Urease among arriving pilgrims and no evidence that amplification of transmission had occurred among departing pilgrims. Hajj, the pilgrimage to the holy city of Makkah, is the largest annual gathering of its kind in the world. It brings more than 2 million pilgrims from 160 countries

together in a small, geographically confined area.1 Most of the pilgrims stay in large air-conditioned tents (in Mina and Arafat) during the whole period of Hajj. It is not unusual for 50–100 people to share a tent overnight.2 This extreme crowding and continuous close contact greatly increases the risk of spreading infectious diseases, particularly those caused by respiratory viruses.3–5 Acute respiratory infections are very common and are responsible for more than half of admissions to Saudi hospitals during Hajj.6 Respiratory viruses, especially influenza virus, are the main cause of acute respiratory infection during the Hajj.7,8 Respiratory specimens have been positive for viral pathogens in 10%–20% of pilgrims with upper respiratory tract infections.