A COMPARISON OF THE VIRULENCE IN THE GUINEA-PIG OF TUBERCLE BACILLI FROM THAI AND BRITISH PATIENTS.

Recent work carried out at the Tuberculosis Chemotherapy Centre, Madras, and at the Postgraduate Medical School of London has shown that isoniazid-sensitive cultures of tubercle bacilli obtained before the start of chemotherapy from South Indian patients with pulmonary tuberculosis are of lower average virulence than corresponding cultures from British patients. The present paper from the Centre extends these studies to areas outside India by comparing isoniazid-sensitive cultures from 81 Thai patients and 67 British patients for their guinea-pig virulence. As assessed by the amount of disease visible at post-mortem examination six weeks after intramuscular injection of the cultures, by the mortality of the guinea-pigs and by the results of spleen culture, the Thai cultures were less virulent than the British cultures. However, a retrospective comparison with the earlier studies suggests that the Thai cultures were intermediate in their virulence between British and Indian cultures. These findings contribute to the over-all study of the geographical distribution of attenuated tubercle bacilli.