Variation in the ITS-1 and ITS-2 rRNA genomic regions of Cytauxzoon felis from bobcats and pumas in the eastern United States and comparison with sequences from domestic cats.

Cytauxzoon felis, a tick-borne protozoan parasite, is the causative agent of cytauxzoonosis in domestic cats in the United States. The natural reservoir for this parasite is the bobcat (Lynx rufus), which typically does not develop clinical signs. Although not likely important reservoirs, C. felis has also been detected in pumas (Puma concolor) in Florida and Louisiana. Recent studies suggest that specific genotypes of C. felis that circulate in domestic cats may be associated with variable clinical outcomes and specific spatial locations. In the current study, we investigated the intraspecific variation of the C. felis internal transcribed spacer (ITS)-1 and ITS-2 rRNA regions from 145 wild felids (139 bobcats and six pumas) from 11 states (Florida, Georgia, Kansas, Kentucky, Louisiana, Missouri, North Carolina, North Dakota, South Carolina, Oklahoma, and Pennsylvania). Unambiguous ITS-1 and ITS-2 data were obtained for 144 and 112 samples, respectively, and both ITS-1 and ITS-2 sequences were obtained for 111 (77%) samples. For the ITS-1 region, sequences from 65 samples collected from wild felids were identical to those previously reported in domestic cats, while the other 79 sequences were unique. C. felis from 45 bobcats and one puma had ITS-1 sequences identical to the most common sequence reported from domestic cats. Within the ITS-2 region, sequences from 49 bobcats were identical to those previously reported in domestic cats and 63 sequences were unique (with some occurring in more than one bobcat). The most common ITS-2 sequence from domestic cats was also common in wild felids (31 bobcats and a puma). Samples from three pumas from Florida and two bobcats from Missouri had a 40- or 41-bp insert in the ITS-2 similar to one described previously in a domestic cat from Arkansas. Additionally, a previously undescribed 198- or 199-bp insert was detected in the ITS-2 sequence from four bobcats. Collectively, based on combined ITS-1 and ITS-2 sequences, five different genotypes were detected in the wild felids. Genotype ITSa was the most common genotype (11 bobcats and one puma) and fewer numbers of ITSb, ITSe, ITSg, and ITSi were detected in bobcats. These data indicate that, based on ITS-1 and ITS-2 sequences, numerous C. felis strains may circulate in wild felids.

Distribution and prevalence of Cytauxzoon felis in bobcats (Lynx rufus), the natural reservoir, and other wild felids in thirteen states.

Cytauxzoon felis, a protozoan parasite of wild and domestic felids, is the causative agent of cytauxzoonosis in domestic and some exotic felids in the United States. The bobcat (Lynx rufus) is the natural reservoir for this parasite, but other felids such as Florida panthers (Puma concolor coryii) and domestic cats may maintain long-term parasitemias and serve as reservoirs. Experimentally, two tick species, Dermacentor variabilis and Amblyomma americanum, have demonstrated the ability to transmit C. felis. These two tick species have overlapping distributions throughout much of the southeastern United States. The objective of the current study was to determine the distribution and prevalence of C. felis in free-ranging bobcat populations from 13 states including California, Colorado, Florida, Georgia, Kansas, Kentucky, Missouri, North Carolina, North Dakota, Ohio, Oklahoma, South Carolina, and West Virginia. These states were selected because of differential vector presence; D. variabilis is present in each of these states except for the region of Colorado sampled and A. americanum is currently known to be present only in a subset of these states. Blood or spleen samples from 696 bobcats were tested for C. felis infection by a polymerase chain reaction (PCR) assay which targeted the first ribosomal internal transcribed spacer region (ITS-1). Significantly higher prevalences of C. felis were detected from Missouri (79%, n=39), North Carolina (63%, n=8), Oklahoma (60%, n=20), South Carolina (57%, n=7), Kentucky (55%, n=74), Florida (44%, n=45), and Kansas (27%, n=41) compared with Georgia (9%, n=159), North Dakota (2.4%, n=124), Ohio (0%, n=19), West Virginia (0%, n=37), California (0%, n=26), and Colorado (0%, n=67). In addition to bobcats, seven cougars (Puma concolor) from Georgia, Louisiana, and North Dakota and one serval (Leptailurus serval) from Louisiana were tested for C. felis. Only one cougar from Louisiana was PCR positive, which represents the first report of an infected cougar outside of the Florida panther population. These data also indicate that C. felis is present in North Dakota where infection has not been reported in domestic cats. Based on a nonparametric analysis, prevalence rates were significantly higher in states where there are established populations of A. americanum, which supports recent data on the experimental transmission of C. felis by A. americanum and the fact that domestic cat clinical cases are temporally associated with A. americanum activity. Collectively, these data confirm that bobcats are a common reservoir for C. felis and that A. americanum is likely an epidemiologically important vector.