Figure 1

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 [19] exactly mirrors the dynamics of schizophrenic births in the north-eastern United States [20]. 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 [21] appears to have given rise to schizophrenic births between February and March along with the typical decline in summer and late autumn [22]. 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 [41] is in line with the apparent absence of Ixodes ticks and B. burgdorferi from that part of the world [40].