INTRODUCTION

Annually more than 2 million pilgrims from all over the world attend the Hajj in Saudi Arabia. Overcrowding during this pilgrimage leads to a high risk of transmission of airborne infectious diseases. Tuberculosis (TB) is common among hospitalized pilgrims, but the overall risk of acquiring Mycobacterium tuberculosis infection during this pilgrimage is not known. We conducted a prospective study to assess the risk of M. tuberculosis infection among Hajj pilgrims.

METHODS

We measured the immune response to TB antigens using a whole-blood assay (QuantiFERON TB assay) prior to departure and 3 months after return from the Hajj pilgrimage.

RESULTS

Of 357 paired assays, 149 pilgrims were negative prior to the Hajj and 15 (10%) of these had a significant rise in immune response to TB antigens.

CONCLUSIONS

Pilgrims may be at high risk of acquiring M. tuberculosis infection during the Hajj. This has significant public health implications for TB control in countries with large Muslim populations.