Antibodies to Leptospira among blood donors in higher-risk areas of Australia: possible implications for transfusion safety

Background: Leptospirosis is one of the most common bacterial zoonoses worldwide, and clinical manifestations range from asymptomatic infection to acute febrile illness, multi-organ failure and death. Asymptomatic, acute bacteraemia in a blood donor provides a potential for transfusion-transmission, although only a single such case from India has been recorded. Human leptospirosis is uncommon in developed countries; however, the state of Queensland in Australia has one of the highest rates among developed countries, especially after increased rainfall. This study examined the prevalence of antibodies to Leptospira spp. in blood donors residing in higher-risk areas of Australia, to evaluate the appropriateness of current blood safety guidelines. Materials and methods: Plasma samples collected from blood donors residing in higher-risk areas of Australia during 2009 and 2011 were included in the study. All samples were tested for the presence of antibodies to 22 leptospiral serovars using the microscopic agglutination test. Result: No sample had antibody titres suggestive of a current or recent infection, however, seven samples (1.44%, 95% CI: 0.38-2.50%) had titres suggestive of a past infection. Discussion: This study provides data that may support the appropriateness of current relevant donor selection policies in Australia. Given that the risk profile for leptospirosis is expanding and that the infection is likely to become more prevalent with climate change, this disease may become more of a concern for transfusion safety in the future.