Anaplasma, Theiler, 1910

Mendoza-Roldan, Jairo Alfonso, Mendoza-Roldan, Miguel Angel & Otranto, Domenico, 2021, Reptile vector-borne diseases of zoonotic concern, International Journal for Parasitology: Parasites and Wildlife 15, pp. 132-142 : 137

3.1.2. Anaplasma and Ehrlichia

The genus Anaplasma comprises species of pathogenic bacteria mainly transmitted by ticks. These Gram-negative bacteria replicate in vertebrate and invertebrate hosts, and can cause severe symptoms and even death in animals, including humans ( Crosby et al., 2021). Among these potentially fatal bacteria, the most important is Anaplasma phagocytophilum , the causative agent of granulocytic anaplasmosis (GA) (Nieto et al., 2009). Although main vectors of this pathogen (i.e., I. pacificus in the Nearctic and I. ricinus in the Palearctic) occasionally feed on reptiles, especially in their immature stages (i.e., larvae and nymphs), studies have shown that reptiles (i.e., lizards and snakes) play a minor role as reservoirs of GA (Nieto et al., 2009). In addition, Anaplasma spp. have been molecularly identified in tick species associated to reptiles to a certain level (e.g., I. ricinus in central and western Europe and H. aegyptium in eastern Europe; Vaclav´et al., 2011; Tijsse-Klasen et al., 2010; Paștiu et al., 2012). Other tick species strictly associated with reptiles such as Amblyomma flavomaculatum (known as yellow-spotted monitor lizard tick from Ghana) and Amblyomma varanense (the Asian monitor lizard tick from Indonesia) were also detected positive for Anaplasma spp. (Nowak et al., 2010; Takano et al., 2019). These Anaplasma spp. were genetically similar to species affecting cattle (e.g., Anaplasma marginale and Anaplasma bovis ), or A. phagocytophilum . Considering that reptiles are widely traded in the international pet market, it is pivotal to monitor imported animals to avoid the spreading of these pathogens and their vectors (Mihalca, 2015; Bezerra-Santos et al., 2021a, 2021b).

Recently, other groups of Anaplasmataceae have been detected from reptiles or their ectoparasites, such as Candidatus Anaplasma testudines detected in Gopherus polyphemus tortoises in Florida, United States ( Crosby et al., 2021). In addition, Canditatus Cryptoplasma sp. REP was described from Lacerta viridis lizards and I. ricinus ticks in Slovakia (Koˇcíkova´et al., 2018), and Podarcis spp. and I. ricinus ticks from Italy (Mendoza-Roldan et al., 2021b). Both of these species of bacteria have an unknow pathogenicity, yet Candidatus Anaplasma testudines seems to be pathogenic to its natural reservoir. In addition, Ehrlichia spp. have been detected in different Acarina ectoparasites of reptiles worldwide. Ehrlichia ruminantium , the causative agent of heartwater disease, common to ruminants and that can occasionally infect humans, has been reported in Amblyomma sparsum from leopard tortoises imported into the United States from Zambia (Peter et al., 2002; Omondi et al., 2017), Ehrlichia chaffeensis and Candidatus Neoehrlichia mikurensis were detected in Amblyomma spp. from reptiles imported to Japan ( Andoh et al., 2015). Possible new species of Ehrlichia were detected in Amblyomma spp. from sea snakes and tortoises also from Japan, closely related to Candidatus Ehrlichia occidentalis . Recent studies highlighted that the diversity of ehrlichial agents might be underestimated and the pathogenicity remains still unknown (Qiu et al., 2021). Other ehrlichial agents were detected from H. aegyptium ticks from Palearctic tortoises in Romania, I. ricinus ticks from lizards of Italy and Amblyomma spp. from snakes of Malaysia (Paș;tiu et al., 2012; Kho et al., 2015; Mendoza-Roldan et al., 2021b), which further indicates that the diversity of ehrlichial microorganisms infecting reptiles is presently underestimated in their pathogenicity, distribution and evolution.