Cryptosporidium spp. in German wildlife: Detection, regional occurrence and diversity in wild boar, roe, red and fallow deer

<i>Cryptosporidium</i> is a cause of diarrheal infections responsible for a loss of human and animal welfare worldwide. The impact of the parasite is underestimated and the reported sources of infection are diverse, as it occurs in a wide variety of hosts. Wildlife has been reported as a notifiable source, but few studies are available on its occurrence in European wild boar and cervid species. To determine the occurrence of <i>Cryptosporidium</i> in game in Brandenburg, Germany, a molecular survey was conducted during the 2017 to 2020 hunting seasons. A total of 562 fecal samples from wild boar (<i>Sus scrofa</i>, <i>n</i> = 262), roe deer (<i>Capreolus capreolus</i>, <i>n</i> = 174), red deer (<i>Cervus elaphus</i>, <i>n</i> = 62), fallow deer (<i>Dama</i>, <i>n</i> = 51) and 13 samples of unspecified species were analyzed for both 18S ribosomal RNA (18S rRNA) and <i>Cryptosporidium</i> oocyst wall protein (COWP) gene sequence regions. PCR results showed that 21.2 % of the samples (<i>n</i> = 119/562) were positive for at least one target gene (18S rRNA: <i>n</i> = 114; COWP: <i>n</i> = 14), but differences in <i>Cryptosporidium</i> occurrence were observed within species and hunting seasons, with variations ranging from 1.8 % to 41.7 % (roe deer), respectively. Analysis of Sanger sequences of the 18S rRNA and COWP PCR products indicated that the <i>C.</i> sp. deer genotype was predominant in deer (roe deer: 86.7 %, red deer: 66.7 %, fallow deer: 58.8 %), while <i>C. suis</i> and <i>C. scrofarum</i> were mainly detected in wild boar (88.5 %). The human pathogenic species <i>C. parvum</i> was detected in only 1.2 % (<i>n</i> = 7) of the samples analyzed, but without a clear indication of a specific wild animal host. The highest <i>Cryptosporidium</i> diversity was found in wild boar and roe deer with five and four different species, respectively. Comparison of the 18S rRNA sequences with the designated reference revealed minor variations at several nucleotide positions in some isolates, possibly indicating evolutionary adaptations and the development of new subtypes. In conclusion, wildlife represents a reservoir for a diverse spectrum of <i>Cryptosporidium</i> species and may thus contribute to their environmental spread and the transmission to humans.