BACTERIA AND VIRUSES THAT CAUSE RESPIRATORY-TRACT INFECTIONS DURING THE PILGRIMAGE (HAJJ) SEASON IN MAKKAH, SAUDI-ARABIA

OBJECTIVE To determine the incidence and type of RTI-causing bacteria and viruses during a period of epidemic infections. METHOD A total of 395 sputum specimens and 761 throat swabs were collected during the 19 91 and 1992 pilgrimage seasons (Haj to Makkah Al-Mukarama, Saudi Arabi a) from patients referred to one hospital and three dispensaries with symptoms of respiratory tract infections. All 761 throat swabs of both Hai seasons were also screened for the presence of viral pathogens wi th monoclonal antibodies specific for 7 viruses known to cause respira tory infections. RESULTS Bacterial pathogens were detected in 118 (29. 9%) specimens. During the 1991 Haj season Haemophilus influenzae was t he most frequent bacterial pathogen detected (10%), followed by Klebsi ella pneumoniae (5.2%), Streptococcus pneumoniae (4.8%), Staphylococcu s aureus (3.8%) and Streptococcus pyogenes (2.4%). In the 1992 Haj sea son Klebsiella pneumoniae was predominant (15.1%), followed by Haemoph ilus influenzae and Streptococcus pneumoniae (12.3%). Screening of all sputum specimens for acid-fast bacteria showed that the overall incid ence rate of tuberculosis was 1%. Cultures from the 761 throat swabs w ere largely negative for bacteria except for Streptococcus pyogenes is olated from 7 patients. Viruses were detected in 148 (19.5%) specimens with influenza A and adenovirus being the most common viruses. CONCLU SION The pattern of virus prevalence in the 1991 and 1992 pilgrimage s easons was identical: influenza A and adenovirus predominated. Thus th ese two viruses should be targeted in future prophylactic measures.