**1. Introduction**

Cryptosporidiosis is a common cause of diarrhea in humans and animals [1,2]. It is one of the most important diseases in both developing countries and industrialized nations due to its importance in diarrhea-associated death in young children and foodborne and waterborne outbreaks of illness [1,3–6]. The etiologic agents of cryptosporidiosis, *Cryptosporidium* spp., have over 40 established species and many genotypes of unknown species status [7]. Among them, approximately 20 species and genotypes have been found in humans [8]. Most human cryptosporidiosis cases are caused by *C. parvum* and *C. hominis*. Other humanpathogenic *Cryptosporidium* spp. include *C. meleagridis*, *C. ubiquitum*, *C. cuniculus*, *C. felis*, *C. canis*, *C. viatorum*, and *C. muris* [7].

Rabbits are a supply of high-quality protein to humans. Reports of the Food and Agriculture Organization of the United Nations (FAO) showed that Egypt was the fourth largest producer of rabbit meat in the world, with approximately 7.6 million rabbits [9,10]. Results of recent studies indicate that rabbits can serve as reservoirs of many zoonotic pathogens [11–13]. They are commonly infected with several *Cryptosporidium* species, especially *C. cuniculus* [13–20]. In recent years, there have been increasing reports of *C. cuniculus* in humans [21–24]. In the United Kingdom and New Zealand, *C. cuniculus* is the third most common *Cryptosporidium* species in patients with diarrhea [24,25].

In recent years, molecular epidemiological studies have been conducted to understand the transmission of *Cryptosporidium* spp. in humans, livestock, and companion animals in

**Citation:** Naguib, D.; Roellig, D.M.; Arafat, N.; Xiao, L. Genetic Characterization of *Cryptosporidium cuniculus* from Rabbits in Egypt. *Pathogens* **2021**, *10*, 775. https:// doi.org/10.3390/pathogens10060775

Academic Editor: Luiz Shozo Ozaki

Received: 28 May 2021 Accepted: 17 June 2021 Published: 20 June 2021

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Egypt [26–34]. Although rabbits are commonly farmed in Egypt, to the authors' knowledge there have been no thorough studies on the distribution and genetic identity of *Cryptosporidium* spp. in rabbits in the country. Therefore, this study was conducted to examine the occurrence, genetic characteristics, and zoonotic potential of *Cryptosporidium* spp. in rabbits from three provinces (El-Dakahlia, El-Gharbia, and Damietta) in Egypt.
