Leptospirosis is a zoonotic infection induced by pathogen bacteria (genus: Leptospira) growing in water polluted by animal fluids. Due to its 10 fold occurence in French overseas aera, and especially in Reunion Island, as compared to metropoly, it is considered as a major public health issue.

An important inter-individual variability in humoral immune response suggests that vaccination should be recommended in exposed subjects.

This cohort study aimed to determine if subjects that have been infected by leptospirosis for 1 to 7 years still remain immunized, and then do not need vaccination.

Every year more than 500 000 severe forms of leptospirosis are diagnosed in Reunion Island. The risk of mucocutaneous contact with contaminated media remains important due to highly aqueous environment.

Cured subjects that have been infected for 1, 2, 3, 4, 5, 6 or 7 years will be enrolled. The qualitative and quantitative humoral immune response to leptospirosis infection will also be evaluated to determine whether they still get protective immunization. Leptospirosis immunization will be evaluated using micro-agglutination test.

Graded immune responses related to the severity and the length of the infection will also be investigated.

Finally, 3 methods used for leptospirosis diagnosis will be compared. It is expected from this study to evaluate the appropriate conditions in which new vaccination could be required to prevent further leptospirosis infection in cured subjects.

Inclusion Criteria:

• Subjects diagnosed for leptospirosis by polymerase chain reaction measured in Reunion Island Hospital between 209-2015
• with social security issue

Exclusion Criteria:

• Leptospirosis diagnosis not confirmed by polymerase chain reaction
• subject exhibiting immunodepressive status (cancers, transplantation, immune deficit, blood disorders)
• under medication: corticoids, immunosuppressor, chemiotherapy

Leptospirosis-cured subjects that have undergone leptospirosis