Feline Vector-Borne Diseases in North America

First identification of Cytauxzoon manul in Eurasian lynx (Lynx lynx) in northwestern China

BACKGROUND

Multiple species of the genera Cytauxzoon and Hepatozoon can infect wild felines, but the diversity of these and other apicomplexan parasites in Eurasian lynx is scarcely known. The aim of this study was to detect Cytauxzoon and Hepatozoon species with molecular methods in Eurasian lynxes and their ticks in northwestern China.

METHODS

DNA was extracted from the heart, liver, spleen, lung, and kidney samples of three Eurasian lynxes as well as from their five ixodid ticks. These DNA samples were screened with polymerase chain reactions (PCRs) for Cytauxzoon with the partial cytochrome b gene (CytB), cytochrome c oxidase subunit I gene (COI), and small subunit ribosomal RNA gene (18S rRNA), and Hepatozoon with three different fragments of small subunit ribosomal RNA gene (18S rRNA). PCR products were sequenced, aligned, and phylogenetically analyzed.

RESULTS

One adult female of Eurasian lynx (#1, adult female) was co-infected with Cytauxzoon manul and Hepatozoon felis genotype I, while an adult male lynx (#2) was infected with C. manul. Interestingly, H. felis genotype I was both detected in a male cub (#3) and two out of five infesting Hyalomma asiaticum ticks.

CONCLUSIONS

For the first time, Cytauxzoon manul is reported here from Eurasian lynx. In addition, H. felis has not been known to occur in this host species in China and Central Asia. Thus, the findings of this study extend our knowledge on the geographical distribution and host range of these haemoprotozoan parasites. Moreover, this is also the first evidence of C. manul and H. felis co-infection in Eurasian lynx.

Granulocytic anaplasmosis in cats from central Europe and molecular characterization of feline Anaplasma phagocytophilum strains by ankA gene, groEL gene and multilocus sequence typing

BACKGROUND

Anaplasma phagocytophilum is a Gram-negative obligate intracellular bacterium that replicates in neutrophil granulocytes. It is transmitted by ticks of the Ixodes ricinus complex and causes febrile illness called granulocytic anaplasmosis primarily in humans, horses, dogs, sheep, cattle and goats. In comparison, clinically apparent disease has been described rarely in cats especially compared to dogs and horses. It is currently unknown whether cats are less susceptible to A. phagocytophilum or whether granulocytic anaplasmosis might be underdiagnosed in cats.

METHODS

To address this question, we examined clinical signs and laboratory findings in seven A. phagocytophilum infected cats from Germany and Switzerland. We then genetically characterized feline A. phagocytophilum strains and compared them to those from other hosts showing clinically apparent disease. For this purpose, ankA-based, groEL-based and multilocus sequence typing (MLST) were applied. Furthermore, the concordance between these typing methods was assessed.

RESULTS

Fever, lethargy and anorexia were the most common clinical signs in cats suffering from granulocytic anaplasmosis. The most frequent laboratory finding was thrombocytopenia. All three typing methods consistently indicated that the A. phagocytophilum strains found infecting cats are the same as those that cause disease in humans, dogs and horses. In general, the three typing methods applied exhibited high concordance.

CONCLUSIONS

The genetic characterization of the feline A. phagocytophilum strains indicates that strain divergence is not the explanation for the fact that granulocytic anaplasmosis is much less frequently diagnosed in cats than in dogs and horses. Otherwise, it may be possible that cats are less susceptible to the same strains than dogs and horse are. However, due to the unspecific clinical signs, it should be considered that granulocytic anaplasmosis may be under-diagnosed in cats.

Vector-borne and other pathogens of potential relevance disseminated by relocated cats

Large populations of unowned cats constitute an animal welfare, ecological, societal and public health issue worldwide. Their relocation and homing are currently carried out in many parts of the world with the intention of relieving suffering and social problems, while contributing to ethical and humane population control in these cat populations. An understanding of an individual cat’s lifestyle and disease status by veterinary team professionals and those working with cat charities can help to prevent severe cat stress and the spread of feline pathogens, especially vector-borne pathogens, which can be overlooked in cats. In this article, we discuss the issue of relocation and homing of unowned cats from a global perspective. We also review zoonotic and non-zoonotic infectious agents of cats and give a list of practical recommendations for veterinary team professionals dealing with homing cats. Finally, we present a consensus statement consolidated at the 15th Symposium of the Companion Vector-Borne Diseases (CVBD) World Forum in 2020, ultimately to help veterinary team professionals understand the problem and the role they have in helping to prevent and manage vector-borne and other pathogens in relocated cats.

Graphical Abstract

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.

DETECTION OF VECTOR-BORNE INFECTIONS IN LIONS AND TIGERS AT TWO ZOOS IN TENNESSEE AND OKLAHOMA, USA

Protozoal and bacterial vector-borne infections are frequently diagnosed in domestic felids. However, with the exception of Mycoplasma haemofelis and Cytauxzoon felis, their occurrence in managed nondomestic felids housed in the United States is largely unknown. Following a case in February 2020 of fulminant cytauxzoonosis in an African lion (Panthera leo), EDTA-whole blood samples were collected opportunistically from February 2020 through June 2020 from 34 adult tigers (Panthera tigris) and eight adult African lions from the same sanctuary in eastern Tennessee as well as 14 adult tigers from a zoo in southern Oklahoma. Samples were analyzed for Cytauxzoon felis, Bartonella spp., hemotropic Mycoplasma, Rickettsia spp., Anaplasma spp., Ehrlichia spp., Babesia spp., and Hepatozoon spp. DNA by PCR amplification. All animals were asymptomatic at the time of collection. None of the Oklahoma animals were positive for vector-borne organisms, but these pathogens were detected in tigers at the Tennessee facility, including Cytauxzoon felis (11.8%), "Candidatus Mycoplasma haemominutum" (5.9%), and Ehrlichia ewingii (2.9%). During the study period, two animals developed clinical signs of cytauxzoonosis and were assessed for vector-borne infections as part of their diagnostic evaluation. This study documents the presence of tick-borne diseases in managed nondomestic felids in the southeastern United States and underscores that ectoparasite control measures should be practiced to minimize exposure of carnivores in managed care.

Prevalence of Vector-Borne Pathogens in Reproductive and Non-Reproductive Tissue Samples from Free-Roaming Domestic Cats in the South Atlantic USA

Reservoir to multiple species of zoonotic pathogens, free-roaming cats (FRCs) interact with domestic and wild animals, vectors, and humans. To assess the potential for feline vector-borne pathogens to be vertically transmitted, this study surveyed ear tip and reproductive tissues of FRCs from two locations in the South Atlantic United States for Anaplasma, Bartonella, Ehrlichia, hemotropic Mycoplasma, and Rickettsia species. We collected ovary (n = 72), uterus (n = 54), testicle (n = 74), and ear tip (n = 73) tissue from 73 cats, and fetal (n = 20) and placental (n = 19) tissue from 11 queens. Pathogen DNA was amplified utilizing qPCR, confirmed by sequencing. Cats were more frequently Bartonella henselae positive on reproductive tissues (19%, 14/73) than ear tip (5%, 4/73; p = 0.02). B. henselae was amplified from fetus (20%, 4/20) and placenta samples (11%, 2/19). Bartonella spp. infection was more common in cats from North Carolina (76%, 26/34) than Virginia (13%, 5/39; p < 0.0001). Fourteen percent (10/73) of both ear tip and reproductive tissues were positive for hemotropic Mycoplasma spp. Anaplasma, Ehrlichia, and Rickettsia spp. DNA was not amplified from any cat/tissue. These findings suggest that B. henselae preferentially infected cats' reproductive tissue and reinforces the importance of investigating the potential for B. henselae vertical transmission or induction of reproductive failure.

Evaluation of the role of Babesia species and Cytauxzoon felis in feline anemia cases in Colorado, USA

Objectives

The aim of this study was to evaluate the blood of cats in Colorado, USA, with suspected infectious causes of anemia for the presence of Babesia species and Cytauxzoon felis DNA. Results of PCR testing for other common vector-borne diseases potentially associated with anemia are also reported.

Methods

Samples from 101 cats were tested using a PCR assay that coamplified the DNA of C felis and Babesia species mitochondrial DNA. PCR testing for DNA of hemoplasmas, Bartonella species, Ehrlichia species, Anaplasma species, Neorickettsia risticii and Wolbachia genera was also performed if not carried out previously.

Results

Twenty-two cats (21.8%) were positive for DNA of an infectious agent. DNA from hemoplasma species were amplified from 14 cats (13.9%). Bartonella species DNA was amplified from four cats (4%) and Ehrlichia canis, Anaplasma platys, Anaplasma phagocytophilum and Wolbachia genera DNA were amplified from one cat each. Babesia species and C felis mitochondrial DNA were not amplified from any sample.

Conclusions and relevance

Based on the results of this study, it does not appear that Babesia species or C felis are clinically relevant in anemic cats in Colorado, USA. For C felis, this suggests that the vector Amblyomma americanum is still uncommon in this geographic area.

Molecular detection of Anaplasma phagocytophilum in hair and spleen of cats revealed a possible underestimation of feline vector-borne pathogens

Feline Vector-Borne Diseases show increased global prevalence and some Anaplasma and Ehrlichia species may pose a risk to human health. The diagnosis of Anaplasma and Ehrlichia species infection in cats is achieved by the combined use of different methods as cytologic examination evidencing intracytoplasmic morulae, serologic tests and molecular assays. The peripheral whole blood is considered the sample of choice for Anaplasma and Ehrlichia species DNA detection in cats, but false negative results are reported leading to underestimation of infection prevalence. In order to have a more accurate assessment of the spread of feline vector-borne pathogens, the presence of Anaplasma spp. and Ehrlichia spp. DNA in 37 owner and shelter cats subjected to necropsy were prospectively investigated by testing in end-point PCR spleen, bone marrow, blood clot and hair samples. The bacteria identified were genetically characterised. Three shelter cats tested positive for A. phagocytophilum DNA in spleen (one cat) or in hair samples (two cats). None of the cats tested positive in bone marrow and blood samples. From the results obtained, it can be assumed that the use of spleen or hair samples could allow a more reliable detection of A. phagocytophilum DNA in cats with blood tested negative. In the phylogeny constructed with a fragment of the heat shock (groEL) gene nucleotide sequences, all the identified A. phagocytophilum clustered with bacteria infecting a wide range of hosts, including humans, showing a potential zoonotic role.

Evaluation of hematological alteration of vector-borne pathogens in cats from Bangkok, Thailand

Background

Cats can be carriers of infected arthropods and be infected with several vector-borne pathogens (VBPs) but there is limited knowledge about their pathogenic role in cats. This study aimed to assess the prevalence of some feline vector-borne agents by molecular technique and to characterize the hematological findings associated with these infections in a cat population from Bangkok Thailand.

Results

PCR was positive with at least one pathogen in 237 out of 372 subjects (63.7%), with prevalence of 39.5% (147/372) for Babesia spp., 36.9% (137/372) for hemoplasmas and 3.2% (12/372) for Hepatozoon spp. The cats older than 1 year were at significantly greater risk for VBPs infection (P = 0.001; OR = 1.43; 95% CI: 1.12 – 1.81) and hemoplasmas infection (χ2 = 10.8, df = 1; P < 0.0001; OR = 2.45; 95% CI: 1.49 – 4.01). A significant association between hematological findings and hemoplasma infection were identified in the present study. Besides, VBPs infection revealed more frequent in male cats (χ2= 6.38, df = 1, P = 0.01). Macrocytic hypochromic type of anemia was observed in cats infested with blood-sucking arthropods compared to the non-infested cats presented.

Conclusions

The current study confirmed that Babesia, Hepatozoon and hemoplasmas had infected semi-domesticated cats in Bangkok, Thailand, with Babesia and hemoplasmas being dominant in prevalence. Some hematological findings were significantly associated with cats infected with vector-borne pathogens in this study including leukocyte count and platelets count that may help support veterinary technicians in diagnosis and appropriate treatment. Campaigns of VBPs monitoring in Bangkok emphasizing on the investigation of vectors and possible routes of the infection in animals should be conducted to prevent the transmission of the pathogens.

First record of Hepatozoon spp. in domestic cats in Greece

Feline hepatozoonosis is an emerging disease of domestic and wild felids though there is limited knowledge of this infection, e.g. regarding geographical distribution and parasite species involved. The present study evaluated microscopically and molecularly the occurrence of Hepatozoon spp. in domestic cats from insular (Crete, Mykonos and Skopelos) and continental (prefectures of Attica and Thessaloniki) Greece. Out of 282 cats examined, 72 (25.5 %) scored positive by PCR for Hepatozoon spp. and of them, 9 (12.5 %) showed gamonts on the blood smear microscopic examination. Sequences obtained from 35 of the amplicons proved the presence of two haplotypes of Hepatozoon felis. One, herein called H1 (34/35 amplicons) resulted 100 % identical with H. felis from Italy and isolates from other continents, and ∼98 % similar with a H. felis isolate causing severe clinical signs in Austria. The haplotype H2, found in a cat in Skopelos, had ∼94 % identity with H1, with H. felis isolates from Italy, Israel, Spain, a ∼92 % identity with the isolate from Austria, and ∼94-98 % with isolates from South Africa. These are the first records of H. felis in cat populations from Greece and indicate that the infection may be present at high prevalences in different regions of the country. Furthermore, the results of the molecular and phylogenetic analysis support a recent hypothesis indicating the existence of a species-complex classification for H. felis. Further studies aiming at elucidating the genetic make-up of Hepatozoon populations and possible variations in terms of geographic distribution and clinical relevance are necessary. The importance of a continuous epizootiological monitoring is crucial for the establishment of preventative and control measures protecting the health of cats living in or travelling to enzootic areas.

Tick-Borne Flavivirus Inhibits Sphingomyelinase (IsSMase), a Venomous Spider Ortholog to Increase Sphingomyelin Lipid Levels for Its Survival in Ixodes scapularis Ticks

Our previous study showed that cells from medically important arthropods, such as ticks, secrete extracellular vesicles (EVs) including exosomes that mediate transmission of flavivirus RNA and proteins to the human cells. Understanding the molecular determinants and mechanism(s) of arthropod-borne flavivirus transmission via exosome biogenesis is very important. In this current study, we showed that in the presence of tick-borne Langat Virus (LGTV; a member of tick-borne encephalitis virus complex), the expression of arthropod IsSMase, a sphingomyelinase D (SMase D) that catalyzes the hydrolytic cleavage of substrates like sphingomyelin (SM) lipids, was significantly reduced in both Ixodes scapularis ticks (in vivo) and in tick cells (in vitro). The IsSMase reduced levels correlated with down-regulation of its activity upon LGTV replication in tick cells. Our data show that LGTV-mediated suppression of IsSMase allowed accumulation of SM lipid levels that supported membrane-associated viral replication and exosome biogenesis. Inhibition of viral loads and SM lipid built up upon GW4869 inhibitor treatment reversed the IsSMase levels and restored its activity. Our results suggest an important role for this spider venomous ortholog IsSMase in regulating viral replication associated with membrane-bound SM lipids in ticks. In summary, our study not only suggests a novel role for arthropod IsSMase in tick-LGTV interactions but also provides new insights into its important function in vector defense mechanism(s) against tick-borne virus infection and in anti-viral pathway(s).

Detection of Flea-Borne Pathogens from Cats and Fleas in a Maltese Shelter

In a sanctuary located on the island of Malta, 23 clinically healthy cats randomly selected were sampled for blood and fleas. Only fleas were collected from 35 cats. All fleas were identified as Ctenocephalides felis, except for one specimen of Ctenocephalides canis. To the best of the authors' knowledge, this may be the first time to establish the occurrence of Bartonella koehlerae and B. clarridgeiae, as well as of Candidatus Mycoplasma haemominutum in the blood samples of 11 cats (47.82% [95% CI: 29.33-67.04]) with conventional PCR assays. One or more pathogens were found in 54 (96.42% [95% CI: 86.74-99.70]) out of 56 pooled flea samples, the most prevalent was Rickettsia felis. The DNA of Bartonella henselae, the commonest etiological agent of cat scratch disease, was detected first time in a pooled flea sample of a cat.