Prevalence of Cytauxzoon felis Infection-Carriers in Eastern Kansas Domestic Cats

CLINICAL AND SUBCLINICAL CYTAUXZOON FELIS INFECTIONS IN DOMESTIC CATS FROM A RECENTLY IDENTIFIED ENDEMIC REGION

Cytauxzoon felis is a tick-transmitted intraerythrocytic apicomplexan infecting felids in the southeastern and midwestern United States. Bobcats (Lynx rufus) are the natural wildlife reservoir of C. felis, where in enzootic areas prevalence can reach 100%. Domestic cats can be subclinically infected with C. felis or can develop cytauxzoonosis. Two studies have documented the presence of C. felis in domestic cats in Illinois; these studies have shown a limited number of cases submitted to specialty labs. During 2014-2018, we obtained blood samples collected by veterinary staff from 514 cats that were apparently healthy and 74 cats that were suspected of cytauxzoonosis. These samples were screened using a sensitive, nested PCR to detect the presence of C. felis DNA. We herein document frequent occurrences of cytauxzoonosis (8-15 cases/year from 4 veterinary clinics) and 12.5% prevalence of subclinical infections in southern Illinois, a locality showing a sharp increase in cases of cytauxzoonosis. Our results suggest a high risk of cytauxzoonosis in southern Illinois, despite only recently being recognized in the area. We found no specific risk factors for cytauxzoonosis or subclinical infections in this location. In addition, cases of cytauxzoonosis occur every month of the year (with the highest frequency in summer) and therefore tick prevention should be used in domestic cats in enzootic regions throughout the year.

Ticks and Tick-Borne Pathogens in Recreational Greenspaces in North Central Florida, USA

Tick-borne infections are an increasing medical and veterinary concern in the southeastern United States, but there is limited understanding of how recreational greenspaces influence the hazard of pathogen transmission. This study aimed to estimate the potential human and companion animal encounter risk with different questing tick species, and the bacterial or protozoal agents they carry in recreational greenspaces. We collected ticks bimonthly along trails and designated recreational areas in 17 publicly accessible greenspaces, in and around Gainesville, Florida, USA. We collected Amblyomma americanum, Ixodes scapularis, Amblyomma maculatum, Dermacentor variabilis, Ixodes affinis, and Haemaphysalis leporispalustris. Across the six tick species collected, we detected 18 species of bacteria or protozoa within the Babesia, Borrelia, Cytauxzoon, Cryptoplasma (Allocryptoplasma), Ehrlichia, Hepatozoon, Rickettsia, and Theileria genera, including pathogens of medical or veterinary importance. While tick abundance and associated microorganism prevalence and richness were the greatest in natural habitats surrounded by forests, we found both ticks and pathogenic microorganisms in manicured groundcover. This relationship is important for public health and awareness, because it suggests that the probability of encountering an infected tick is measurable and substantial even on closely manicured turf or gravel, if the surrounding landcover is undeveloped. The presence of medically important ticks and pathogenic microorganisms in recreational greenspaces indicates that public education efforts regarding ticks and tick-borne diseases are warranted in this region of the United States.

Can Domestic Cats Act as Reservoirs of Cytauxzoon felis?

Cytauxzoonosis is a worldwide tick-borne disease of domestic and wild felids, caused by infection of the haemoparasites belonging to the genus Cytauxzoon (Piroplasmida, Apicomplexa), which are apicomplexan protozoans closely related to those of the genera Babesia and Theileria [...].

Cytauxzoon felis: An Overview

Cytauxzoon felis is a tick-transmitted, obligate, hemoprotozoal, piroplasmid pathogen of felids and the causative agent of cytauxzoonosis. It has a complex life cycle which includes a tick as its definitive host and a felid as its intermediate host. Since its first description in 1976, C. felis infections of felids have been reported in several southeastern and south-central U.S. states, overlapping with the ranges of its two known biological vectors, Amblyomma americanum (Lone star tick) and Dermacentor variabilis (American dog tick). Infected felids demonstrate disease as either an acute, often-fatal, infection, or a subclinical carrier infection. To develop effective C. felis transmission control strategies, the incidence of acute cytauxzoonosis, patient risk factors, the role of domestic cat carriers, and ecological variabilities need to be investigated further. Of equal importance is communicating these strategies for high-risk cat populations, including recommending year-round use of an acaricide product for all cats that spend any time outdoors. More studies are needed to further identify factors affecting C. felis and other Cytauxzoon spp. infection, transmission, disease progression, and treatment options and outcomes within the U.S. and globally. Here we provide an overview of C. felis highlighting its lifecycle within its definitive host, transmission to its intermediate host, symptoms and signs providing evidence of transmission, definitive diagnosis, current treatment and prevention strategies, and future considerations regarding this condition.

Clinicopathological findings and risk factors associated with Cytauxzoon spp. infection in cats: A case-control study (2008–2021)

In Europe, Cytauxzoon spp. infection was documented in domestic and wild felids. Cats often develop a subclinical infection, while fatal disease is rare. Currently, information on the epidemiology, risk factors and clinicopathological findings of Cytauxzoon spp. infection remains limited and obtained by a single subject or small groups of cats. The objective of this case-control study was to evaluate clinicopathological findings and to describe risk factors associated with Cytauxzoon spp. infection in domestic cats. Infected cats (n = 39) and non-infected (n = 190) cats were selected from the database of the referral San Marco Veterinary Laboratory between 2008 and 2021. Demographic information, a preset questionnaire considering lifestyle, environment, and clinical status, and a CBC performed contextually with the PCR analysis were recorded for all cats. Data on the biochemical profile and serum protein electrophoresis were also evaluated when available. Compared to the control group, infection was more likely to occur in stray cats (24/39, 61.5%, P < 0.001), living totally/partially outdoors (36/39, 92.3%, P < 0.001), in an urban context (37/39, 94.9%, P = 0.002), taken or recently adopted from colonies (34/35, 97.1, P < 0.001), with irregular or absent parasite preventive treatments (39/39, 100%, p = 0.005), without fleas (28/35, 80%, P = 0.047) and without clinical signs (22/39, 56.4%, p = 0.026) at the time of medical evaluation. Anemia was not associated with infection, but in cats without clinical signs, the percentage of anemic-infected cats (7/22, 31.8%, P = 0.009) was higher compared to non-infected cats (5/65, 7.7%). Furthermore, a decrease in total iron serum concentration approximating the lowest reference interval [median values (IQR): 79 μg/dL (52.25) vs. 50.5 μg/dL (34), P = 0.007] was likely in infected cats. No other laboratory findings were associated with infection. Interestingly, a partial/total outdoor lifestyle was a risk factor for infection (OR: 8.58, 95% CI: 2.90–37.0, P < 0.001). In conclusion, the present study revealed that Cytauxzoon spp. infection manifests itself prevalently as a subclinical infection, based on physical examination and laboratory findings, in domestic European cats. However, subclinical infected cats were more likely to be anemic compared to non-infected.

Piroplasmid infection is not associated with clinicopathological and laboratory abnormalities in cats from Midwestern Brazil

Feline piroplasmids include the genera Babesia spp., Cytauxzoon spp., and Theileria spp. In Brazil, there are few reports regarding these hemoprotozoans; however, clinicopathological and molecular data are scarce. This study aimed to characterize the clinical relevance of these parasites through hematological, biochemical, and molecular approaches. For this purpose, 166 cats from Brasilia, Federal District, Midwestern Brazil, were screened using a quantitative polymerase chain reaction (qPCR) for piroplasmids based on the LSU4 mitochondrial gene, which resulted in an overall prevalence of 36/166 (21.7%). Twelve of 166 samples (7.2%) were positive for C. felis, while 19/166 (11.4%) were positive for Babesia vogeli. No samples tested positive for Theileria spp. Babesia vogeli and Cytauxzoon spp. LSU4 sequences showed identities of 97-100% and 99.3%, respectively, to US isolates. The hematological and biochemical findings did not differ significantly between the cats that tested positive and negative for piroplasmids. Although the lack of abnormalities in clinical and laboratory parameters does not eliminate the possibility that these cats were sick and recovered, it may suggest that the Brazilian strain of Cytauxzoon spp. is not as pathogenic as that from the USA, despite the high molecular identity with North American isolates.

Canine and Feline Parasitology: Analogies, Differences, and Relevance for Human Health

Cats and dogs are treated as family members by most pet owners. Therefore, a high quality of veterinary care and preventive medicine is imperative for animal health and welfare and for the protection of humans from zoonotic pathogens. There is a general perception of cats being treated as "small dogs," especially in the field of clinical parasitology. As a result, several important differences between the two animal species are not taken into proper consideration and are often overlooked. Dogs and cats are profoundly different under evolutionary, biological, ethological, behavioral, and immunological standpoints. These differences impact clinical features, diagnosis, and control of canine and feline parasites and transmission risk for humans. This review outlines the most common parasitoses and vector-borne diseases of dogs and cats, with a focus on major convergences and divergences, and discusses parasites that have (i) evolved based on different preys for dogs and cats, (ii) adapted due to different immunological or behavioral animal profiles, and (iii) developed more similarities than differences in canine and feline infections and associated diseases. Differences, similarities, and peculiarities of canine and feline parasitology are herein reviewed in three macrosections: (i) carnivorism, vegetarianism, anatomy, genetics, and parasites, (ii) evolutionary adaptation of nematodes, including veterinary reconsideration and zoonotic importance, and (iii) behavior and immune system driving ectoparasites and transmitted diseases. Emphasis is given to provide further steps toward a more accurate evaluation of canine and feline parasitology in a changing world in terms of public health relevance and One Health approach.

Cytauxzoonosis in North America

Cytauxzoonosis is an emerging tick-borne disease of domestic and wild felids produced by infection of Cytauxzoon felis, an apicomplexan protozoan similar to Theileria spp. Transmitted by Amblyomma americanum, lone star tick, and Dermacentor variabilis, American dog tick, infection of C. felis in cats is severe, characterized by depression, lethargy, fever, hemolytic crisis, icterus, and possibly death. Cytauxzoonosis occurs mainly in the southern, south-central, and mid-Atlantic United States in North America, in close association with the distribution and activity of tick vectors. Infection of C. felis, although severe, is no longer considered uniformly fatal, and unless moribund, every attempt to treat cytauxzoonosis cats should be made. Herein we review cytauxzoonosis, including its etiology, affected species, its life cycle and pathogenesis, clinical signs, diagnosis, and epidemiology, emphasizing clinical pathology findings in cats infected with this important emerging tick-borne disease in North and South America.

Acute Cytauxzoon felis Cases in Domestic Cats from Eastern Kansas, a Retrospective Case-Control Study (2006-2019)

Cytauxzoon felis, a tick-borne hemoprotozoal pathogen of felids, causes an acute, often-fatal disease in domestic cats. While public awareness of the disease has increased, few studies have evaluated the incidence of acute cytauxzoonosis cases and their associated risk factors. The objective of this study was to retrospectively review records of cats diagnosed with acute cytauxzoonosis in eastern Kansas from 2006–2019 using clinic records and determine: (i) feline cytauxzoonosis risk factors; and (ii) if cytauxzoonosis case incidence is increasing. Although inter-annual variation of acute cytauxzoonosis diagnosis was observed in the eastern Kansas domestic cat population, the overall incidence trend remained largely unchanged over the 14-year case review period. In comparison to ill (C. felis-unrelated) control cases, more acute cytauxzoonosis cases were diagnosed in spring and summer, suggesting a seasonal fluctuation of infection, with samples most commonly submitted from ≥1 year old, owned, male cats. Although cytauxzoonosis case submissions remained consistent over the broad study period, increasing tick vector and domestic cat reservoir populations may contribute to additional cytauxzoonosis case expansion in endemic areas. Investigating the incidence of acute cytauxzoonosis, patient risk factors, and ecological variables that influence disease transmission are important steps towards developing and communicating the need for effective cytauxzoonosis control strategies for high-risk cat populations.