Seasonal correlation of sporadic schizophrenia to Ixodes ticks The seasonal periodicity of the adult and juvenile stages of Ixodes scapularis in the State of New York  exactly mirrors the dynamics of schizophrenic births in the north-eastern United States . The spring and autumn populations of Ixodes ricinus in central Europe are affected by microclimatic conditions and a drop in humidity in midsummer (a = exposed meadow, b = dense hill vegetation or secondary deciduous woodland, c = highly sheltered habitat, d = spring-derived but autumn-feeding cohort). In northern Europe, however, there exists no late autumn cohort (d) as tick activity comes to a halt due to falling ambient temperature. Data adapted from [14, 15, 19, 23, 24]. The seasonal distribution of Ixodes persulcatus ticks in the Far East  appears to have given rise to schizophrenic births between February and March along with the typical decline in summer and late autumn . In the case of a prenatal infection at the time of conception, nine months later these variables run parallel to the birth excess number of individuals with schizophrenia. In Singapore, by contrast, the non-significant birth excess in schizophrenia  is in line with the apparent absence of Ixodes ticks and B. burgdorferi from that part of the world .