Blastocystis

Kaczmarek, Adam, Sobocinski, Wojciech, Wesołowska, Maria, Elzbieta, Gołąb, Kołodziej-Sobocinska, Marta & Sałamatin, Rusłan, 2021, Blastocystis occurrence and subtype diversity in wild European terrestrial mammals - The case of Białowieza ˙ Primeval Forest (NE Poland), International Journal for Parasitology: Parasites and Wildlife 16, pp. 120-125 : 122-123

4.1. Mammalian orders and families infected with Blastocystis

4.1.1. Arctiodactyla

4.1.1.1. Bovidae – European bison (Bison bonasus). European bison is a poorly studied group of mammals in terms of Blastocystis infection. So far, the ST10 subtype has been detected only in captive European bison from a UK zoo ( Betts et al, 2018, 2020). Previously, Alfellani et al. (2013) tested only one sample from European bison from Poland, but they obtained a negative result. Our research showed that the prevalence of Blastocystis infection in the wild European bison population in the BPF is 5.6%.

The Blastocystis sequences obtained as a result of analysis of the European bison faecal samples from BPF belong to four different subtypes – ST1, ST3, ST5 and ST7. The ST1 and ST3 detected in European bison individuals are among the most common of Blastocystis in humans, while ST5 and ST7 are also found in humans, but more often in animals ( Kaczmarek et al., 2017). So far, the ST3 subtype has not been detected in animals in Poland. Subtypes ST10 and ST14, other than those found in our population of European bison, were found in the species related to European bison – the American bison from the French zoo in La Palmyre ( Cian et al., 2017). It is known that the resettlement of European bison from BPF, resulting from the history of the species and the current management of its populations, may cause transmission of diseases to various parts of Europe ( Vadlejch et al., 2017). Every new pathogen found in this vulnerable species may pose a real threat and should be continuously monitored.

4.1.1.2. Suidae – wild boar ( Sus scrofa ). The ST5 subtype found in our studies in wild boar populations is characteristic for Suidae ; previously

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ST5 was also detected in wild boar in Spain ( Rivero-Juarez et al., 2020), in the same study ST5 subtype (as well as ST1 and ST3) was detected in Black Iberian pig. Blastocystis ST 5 is also found in other animals, but it can infect humans as well (Rudzinska´et al., 2020; Stensvold et al., 2009).

The study conducted by Ithoi et al. (2011) indicated that the faeces of wild boar and other wild animals were probably the source of Blastocystis contamination in the Malaysia River. We can expect a similar situation in Poland; in the only PCR study of river water conducted so far in Poland, the presence of Blastocystis ST 1 and ST 3 in north-west Poland was detected ( Adamska, 2020). Under the conditions of central and eastern Europe, wild boar is a species living in relatively high densities, which may affect the rapid transmission of diseases and pathogens within groups (Podgorski´et al., 2018). However, the transmission of parasites, including Blastocystis , by wild boars can also be favoured by low densities of this species. Such a situation is currently observed in eastern Poland as a result of the high mortality rate caused by African swine fever (ASF) ( Morelle et al., 2020). It is fostered by the method of fighting ASF, relying on carcass disposal from the forest (wild boars also feed on carrion). The scarcity of food may increase the mobility of live individuals, which contributes to the spread of diseases and pathogens ( Pepin et al., 2020).

4.1.1.3. Cervidae – red deer ( Cervus elaphus elaphus ). Blastocystis has already been detected in red deer - the ST4 and ST10 subtype in Great Britain ( Betts et al., 2018), the ST4 subtype in Australia ( Roberts et al., 2013), and the ST10 subtype in China and Malaysia ( Li et al., 2020; Rauff-Adedotun et al., 2020; Zhao et al., 2017, 2018). The present study found infection with the ST1 Blastocystis subtype in BPF red deer. In our opinion, among all the mammals in which we detected Blastocystis in the Białowieza ˙Primeval Forest, the red deer is the species with the lowest possibility of transmitting diseases and pathogens over long distances. The unpublished results of the hunting inventory indicate that its density has not changed significantly in recent times. However, some authors show that red deer contribute to the transmission of certain diseases ( Vikøren et al., 2019).

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