Despite housing ∼18% of the world's population, India does not yet have an estimate of prevalence of autism. This study was carried out to estimate the prevalence of autism in a selected population of school‐children in India. N = 11,849 children (mean age = 5.9 [SD = 1.3], 39.5% females) were selected from various school types from three boroughs in Kolkata, India. Parents/caregivers and teachers filled in the social and communication disorders checklist (SCDC). Children meeting cutoff on parent‐reported SCDC were followed up with the social communication questionnaire (SCQ). SCQ‐positive children were administered the autism diagnostic observation schedule (ADOS). Teacher report on SCDC was available on all 11,849 children. Parent‐report SCDC scores were obtained for 5,947 children. Mean scores on teacher SCDC were significantly lower than parent SCDC. Out of 1,247 SCDC‐positive children, 882 answered the SCQ, of whom 124 met the cutoff score of 15. Six of these children met criteria for autism, autism spectrum disorder (ASD), or broader autism spectrum on the ADOS. The weighted estimate of supra‐threshold SCQ scores was 3.54% (CI: 2.88–4.3%). The weighted prevalence estimate of positive scores (for broader autism spectrum + ASD + autism) was 0.23% (0.07–0.46%). As ∼20% children in this state are known to be out of the school system, and ASD prevalence is likely to be higher in this group, this estimate is likely to represent the lower‐bound of the true prevalence. This study provides preliminary data on the prevalence of broader‐spectrum autism and supra‐threshold autistic traits in a population sample of school children in Eastern India. Autism Res 2017, 10: 1597–1605. ©2017 The Authors Autism Research published by Wiley Periodicals, Inc. on behalf of International Society for Autism Research

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Aims India does not yet have an estimate of prevalence of autism and autistic traits in the general population. Estimates drawn from studies in UK and USA suggest that India could have more than 2 million people with ASC; this prevalence estimate has never been verified. There is a critical need to measure the prevalence of autism and the distribution of autistic traits in a general population sample in India. Method Schools from all socio-economic sectors were selected from 3 boroughs. Teachers filled in the Social Communication Disorder Checklist (SCDC), a 10-item initial screening measure for autism (Skuse et al., 1995), in English or Hindi or Bengali. Parents filled in the SCDC, followed by the Social Communication Questionnaire (SCQ), a 40-item diagnostic tool (Rutter et al., 1999) – and the Autism Quotient – child version (AQ-C), a 50-item tool quantifying the distribution of autistic traits (Auyeung et al., 2009). Results SCDC: Teacher reports were obtained for 12764 children. 3.6% met the cut-off score of 9, with 3.8% meeting cutoff on English, 5.49% on Hindi and 1.29% on Bengali versions of the tool. Parent response rate for SCDC was 50.1%. 20.19% met cut off on SCDC parent report overall. 21.67% met cutoff on English, 10.24% on Hindi, and 20.11% on Bengali versions of the tool. Correlation between parent and teacher ratings were modest (r = 0.103, p < 0.001). SCQ: Of 2887 respondents 8.9% met the cut-off score of 15, overall. Specifically 9.64% met cut-off on English, 8.26% on Hindi, and 10.09% on Bengali versions of the tool. AQ-C: Of 2901 respondents 9.86% met the cut-off score of 76. Specifically, 9.48% met cutoff on English, 11.25% on Hindi and 8.67% on Bengali versions of the tool. Conclusions This is the first study providing data on the distribution of autistic symptoms in 12764 children in India. The results suggest over-reporting by parents in comparison to teachers, irrespective of language. This provides important directions for future epidemiological research into autism in India.