Prevalence of antibodies to Toxoplasma gondii among blood donors in Abha, Asir Region, south-western Saudi Arabia.

One thousand samples of sera from healthy blood donors in the Asir Central Hospital, a tertiary facility in the Southwestern part of Saudi Arabia, were screened for Toxoplasma gondii IgG antibodies by the Indirect Haemagglutination Antibody (IHA) test. A prevalence of 52.1% was found. Seropositivity increased with age. The Geometric Mean Titre (GMT) of IHA antibodies was 596.7. While the prevalence increased with age, the GMT declined in the higher age groups. Three hundred sixty six of these sera were also tested for specific IgM titres by micro ELISA technique and 4.1% were found positive, indicating possible acute or recent infection. These serological studies indicate a higher prevalence of toxoplasmosis among healthy blood donors in the Asir region compared to earlier seroprevalence studies in other areas of Saudi Arabia. The high frequency in antibody titres might be due to differences in climatic conditions, culinary habits and exposure to the sources of infection. In view of these findings, it is felt that when considering blood transfusion for a special group of patients (i.e. immunocompromised or immunosuppressed), it would be wise to exclude those with evidence of previous exposure to T. gondii.