Babesia conradae

Javeed, Nadia N., Shultz, Laura, Barnum, Samantha, Foley, Janet E., Hodzic, Emir, Pascoe, Emily L., Martínez-Lopez, Beatríz, Quinn, Niamh, Bucklin, Danielle & Dear, Jonathan D., 2022, Prevalence and geographic distribution of Babesia conradae and detection of Babesia vogeli in free-ranging California coyotes (Canis latrans), International Journal for Parasitology: Parasites and Wildlife 19, pp. 294-300 : 297-298

4.1. Babesia conradae

The present study testing 461 splenic samples using molecular techniques has established that California coyotes can be infected with B. conradae and B. vogeli . To our knowledge, this is the first documentation of infection of B. conradae in free-ranging coyotes. The overall prevalence of this infection found was 4.8%. Although the true prevalence of B. conradae is not known in domestic dogs, our results are much higher than the prevalence of infection reported in domestic dogs (ranging from 0.01 to 2.6%) (Barash and others 2019; Yamane and others 1994).

This new evidence of naturally occurring infection in free-ranging coyotes is the first step to investigating coyotes as a potential reservoir of canine babesiosis for domestic dogs. However, the infection prevalence, in conjunction with previous evidence that dogs with aggressive interaction with coyotes are at greater risk of becoming infected with B. conradae (Dear and others 2018), supports the hypothesis that coyotes could be a source of infection for domestic dog populations. The few, consistent nucleotide differences in the coyote sequences compared to those from domestic dogs may be explained by differences in geographic region or different strains. In this study, only samples from Fresno were successfully sequenced. This is a limitation as there might be regional differences within the genome that were not identified. Sequencing larger portions of the genome and samples from more infected coyotes in more areas could help inform the extent of transmission between dogs and coyotes. Similarly, comparing the geographic distribution between dogs and coyotes was not possible in the present study. However, previous cases of B. conradae infection have been reported in the same areas that positive coyotes were identified in this study (Conrad and others 1991; Dear and others 2018; Yamane and others 1994). The previously reported prevalence in domestic dogs suggests that exposure to and infection with this protozoa is uncommon in domestic dogs but should be considered in animals with consistent clinical signs, potential exposure to wildlife and history of living in California.

If coyotes experience a similar clinical disease as dogs when infected, this pathogen has the potential to have a major impact on coyote populations. Babesia conradae tends to be more pathogenic than large Babesia spp. infecting canids. Infected dogs experience a profound anemia and thrombocytopenia, which can progress to hepatitis, glomerulonephritis, and protein losing nephropathy if left untreated (Wozniak and others 1997). Clinical signs can be severe and include lethargy, vomiting, pyrexia, and weight loss (Conrad and others 1991; Dear and others 2018). Although disease from B. conradae has not been

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studied in coyotes, infection with other closely related species of Babesia produces similar lesions in coyotes as those found in dogs (Evers and others 2003; Roher and others 1985). It is also possible that, if a reservoir species, the organism may be better adapted to persistent, and perhaps less severe clinical infection in order to maintain infection in the population. Regardless, more investigation of the disease history of B. conradae in this newly detected host species is required to determine the extent to which it impacts coyote health.

Coyotes found in a rural setting and from Fresno County were at increased risk for infection with B. conradae . However, these two variables were closely associated in this study, with nearly all the coyotes found in Fresno County from rural areas and nearly all the coyotes from southern California from urban areas. This might be influenced by regional coyote density or vector density, but further investigation into the mechanisms of transmission of B. conradae is needed to speculate the cause of these findings. As no pups were found to be infected, further research into vertical transmission is needed to determine if this is a possible route of infection as has been suggested in other Babesia species.