"The average prevalence of ASD [autism spectrum disorder] was 35/10 000 children and was about 4-fold higher in males."
I don't have too much to add to the findings reported by Karolina Skonieczna-Żydecka and colleagues  who estimated the prevalence of ASD in two regions of Poland: "West Pomeranian and Pomeranian regions." Based on the analysis of data from "Provincial Disability Services Commissions", researchers concluded that approximately 3 children in 1000 in those regions have a diagnosis on the autism spectrum. As always: "More studies are necessary."
Accepting that there may true geographical variations in the rate of autism around the globe  (including effects potentially related to factors such as migration for example), these figures are surprisingly conservative compared with what has been mentioned in other parts of the world in recent times (see here). Yes, one could eventually look at issues around the identification and diagnosis of autism (including translation of the appropriate screening and assessment instruments), what criteria you use to define autism, the potential effect(s) of service availability and delivery following a diagnosis and specific cultural factors to account for the low estimates, but at the moment we can only go with the data that is available. Indeed, this is not the first time that I've talked about other geographic areas also reporting a low prevalence of autism and the possible factors around that example (see here).
I do expect to see the autism prevalence estimates increase in Poland as more detailed study is done such as that actually going looking for those who possibly fall on the autism spectrum (see here) rather than relying on more passive methods of reporting. As per previous peer-reviewed research coming out of Poland , fulfilling the criteria for autism and actually receiving a diagnosis are not necessarily one and the same for whatever reason(s).
But again, we can only go with the available data...
Music: Frank Sinatra - Come Fly With Me.
 Skonieczna-Żydecka K. et al. The Prevalence of Autism Spectrum Disorders in West Pomeranian and Pomeranian Regions of Poland. J Appl Res Intellect Disabil. 2016 Jan 14.
 Fombonne E. et al. Prevalence of Autism Spectrum Disorders in Guanajuato, Mexico: The Leon survey. J Autism Dev Disord. 2016 Jan 21.
 Wolańczyk T. et al. Features of autism, autistic traits, autism: retrospective analysis of clinical symptoms in children treated in the Pediatric Psychiatric Clinic. Psychiatr Pol. 2001 Jan-Feb;35(1):59-69.
Skonieczna-Żydecka K, Gorzkowska I, Pierzak-Sominka J, & Adler G (2016). The Prevalence of Autism Spectrum Disorders in West Pomeranian and Pomeranian Regions of Poland. Journal of applied research in intellectual disabilities : JARID PMID: 26771078