Determination by Widal agglutination of the baseline titre for the diagnosis of typhoid fever in two Nigerian states.

This study was carried out in Borno and Plateau States of Nigeria to determine the baseline titre for the diagnosis of typhoid fever using a single Widal test. Of 172 patients with symptoms and signs of typhoid fever, 92.4% and 90.7% had reciprocal O and H antibody titres respectively of 160 or above. On the other hand, 95.3% and 66.3% of the 937 healthy control subjects had reciprocal O and H antibody titres respectively of 80 or less. The results of this study suggest that in Borno and Plateau States of Nigeria a reciprocal O antibody titre of 160 and above in persons with illness whose symptoms and signs are compatible with typhoid fever could be considered diagnostic using the single Widal test.