Anti-Plesiomonas shigelloides agglutinating and complement-fixing antibody titres in normal individuals and diarrhoeal patients in Edo State, Nigeria.

One hundred patients with diarrhoea and 50 asymptomatic individuals attending various hospitals in Edo State, Nigeria, were screened for serum complement-fixing and agglutinating antibodies to Plesiomonas shigelloides using the complement-fixation and agglutination tests. Seventy (70%) of the 100 patients and 20 (40%) of the 50 asymptomatic individuals had detectable complement-fixing antibodies at titres ranging from 1:32 to 1:128 and 1:8 to 1:32 respectively. Results suggest that cases of diarrhoea in this environment may be due to P. shigelloides, but the demonstration of antibodies in asymptomatic individuals show that they also have serum antibodies against P. shigelloides. The exclusive use of antibody responses in the diagnosis of P. shigelloides infections should, therefore, be interpreted with caution.