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Seropositivity in Clinical Influenza Cases among Pilgrims during Hajj, 1421 H.


Influenza is a major health problem, whether measured by its morbidity, mortality or economic impact. Detection of influenza infection in Hajj can be difficult since its clinical presentation is atypical, and other pathogens also cause influenza-like illness during Hajj. The use of laboratory tests for detection of influenza in conjunction with acceptable case definitions of influenza leads to recognition of seropositive cases aiming to reduce transmission and initiation of infection control measures.


A Cross-sectional study was conducted among selected flu cases among pilgrims visiting out-patient clinics in certain Makkah and Mina hospital settings. Each pilgrim who met the case definition was interviewed using a standard questionnaire prepared in different languages. The questionnaire inquired about personal data, clinical manifestations, past medical history, habits and environmental factors and vaccination status to influenza. After getting a verbal patient consent, 10 ml venous blood was collected for serology.


The total number of patients meeting our clinical case definition from whom samples were obtained were 305 pilgrims; 45 of who were seropositive (14.8%). Among the 45 seropositive cases 60% were influenza type B, 27% were type A, and the rest were positive for both types A and B. Seropositivity appeared to fall with increasing age. Males constituted 90% of the sample, 15.3% of who were seropositive compared to 9.6% among females. American, European and Australian pilgrims had the highest positive rate of influenza virus, followed by South East Asians with statistical significant association. There was no difference in seropositivity on the basis of clinical presentation among flu cases attending different hospital settings. The seropositivity by each of these clinical presentations ranged between 12.6% to 20%, with no statisitical significant difference. Smokers were two times more likely to be seropositive (95% CI 1.2 to 5.7). Among cases who had been vaccinated against influenza 8% were seropositive, compared to 15% among unvaccinated cases. The risk of seropositivity was 35% less among vaccinated groups but was not statistically significant.


We recommend the establishment of surveillance of influenza-like illness to provide an estimate of influenza morbidity, mortality, and economic impact. Further epidemiological studies to identify the spread of Influenza and vaccination among pilgrims should be conducted. Health education should concentrate upon the increased risk and severity of flu infection among smokers. High risk pilgrims should be vaccinated in their home countries.