GUIDELINE for Anaplasma, Ehrlichia, Rickettsia infections

Published: 01/01/2017
Last updated: 15/06/2022
Last reviewed: 01/11/2022

These guidelines were drafted by Maria Grazia Pennisi and co-authored by Alan Radford and Séverine Tasker et al.  They were published in the Journal of Feline Medicine and Surgery 19, 2017, 542-548 by Maria Grazia Pennisi et al. This update has been compiled by Maria Grazia Pennisi.

Key points

  • Anaplasma spp., Ehrlichia spp. and Rickettsia spp. are vector-borne pathogens infecting many mammalian species, but causing disease in very few of them. Anaplasma phagocytophilum is the most important feline pathogen among them and co-infections are possible.
  • The geographical distribution of AnaplasmaEhrlichia and Rickettsia pathogens overlaps with that of their competent vectors (ticks and fleas).
  • Little information is available on the pathogenesis of these agents in cats.
  • Infection can be asymptomatic, or clinical signs are usually reported soon after tick infestation.
  • The most frequent clinical signs are non-specific and consist of fever, anorexia and lethargy. Joint pain may occur.
  • Blood or buffy-coat smear evaluation may be useful for cytological diagnosis of infections with Ehrlichia and Anaplasma spp.
  • Blood PCR analysis is a sensitive and specific method for confirming diagnosis at the onset of acute clinical signs, provided samples are obtained before starting therapy.
  • Cats with clinical signs are usually antibody negative due to inadequate time for seroconversion.
  • Antibodies to rickettsial infections can be detected by immunofluorescence (IF) test and ELISA, but cross-reactions exist between organisms of the same genus.
  • Doxycycline is the first choice antibiotic for treating rickettsial infections.
  • Regular treatment with appropriate ectoparasiticides protects cats from transmission of infection by the competent vectors.
  • In endemic areas blood donors should be tested for rickettsial blood-borne infections.
  • Some species (A. phagocytophilum, Ehrlichia chaffeensis, Ehrlichia ewingii, Rickettsia conorii, Rickettsia rickettsii, Rickettsia felis, Rickettsia typhi) are of zoonotic concern.
  • Infected cats are “sentinels” for the presence of rickettsial pathogens in ticks and fleas in a given geographical area and they signal a risk for people exposed to vectors.
  • Direct contact with cat saliva should be avoided because of the potential contamination by R. felis as well as by other zoonotic pathogens.

Agent properties

Obligate intracellular Gram negative coccoid organisms of the AnaplasmaEhrlichia and Rickettsia genera are vector-borne members of the Rickettsiales order infecting humans and a wide variety of domestic and wild animals worldwide (Allison and Little, 2013). They generally have a low host specificity, considering that many mammalian species can be infected. Importantly, some hosts might serve as reservoirs of infection; however, susceptibility to disease is usually more restricted.

AnaplasmaEhrlichia and Rickettsia are difficult to culture in vitro; molecular genetics have opened new avenues to study their infection biology (Allison and Little, 2013). Compared to dogs, these pathogens have been generally less studied in cats (Table 1).

 
Ehrlichia genusCountries in which cat infection has been detected
E. canisEUROPE: Portugal Spain Italy
AFRICA: Angola
ASIA: Qatar
AMERICAS: US Brazil Saint Kitts
OCEANIA: Guam (Micronesia)
E. chaffeensisAMERICAS: US Brazil
E. ewingiiAMERICAS: US
Anaplasma genus
A. phagocytophilumEUROPE: Sweden Finland Poland Switzerland Germany Austria Italy Spain
AMERICAS: US Brazil
ASIA: Korea
A. platysEUROPE: Cyprus Turkey
AMERICAS: US Brazil Chile
A. platys-likeEUROPE: Italy
AMERICAS: Brazil
A. bovisASIA: Japan
AFRICA: Angola
Rickettsia genus
R. rickettsiiAMERICAS: US Saint Kitts
R. conoriiEUROPE: Spain Portugal
R. massiliaeEUROPE: Spain Portugal
Rickettsia spp.EUROPE: Italy

Table 1: Members of the Ehrlichia, Anaplasma and Rickettsia genera detected in cats in various countries. Please note that the rickettsial infections may occur even in additional countries, however, not published so far. Therefore it is possible that cats are infected in a larger range of countries, not listed in this table, particularly in areas where the competent tick vectors are abundant (see the text).

Anaplasma and Ehrlichia spp. are tick-borne pathogens belonging to the Anaplasmataceae family and are pleomorphic intravacuolar organisms that replicate in haemopoietic cells. They give rise to cytoplasmic inclusion bodies: small elementary bodies (0.2-0.4 µm diameter), larger reticulate bodies and morulae (up to 2-6 µm diameter). Anaplasma phagocytophilum replicates in myeloid cells (mostly in neutrophils; Fig. 1) and is the agent of granulocytotropic anaplasmosis. It infects people and a wide range of animal species worldwide, especially in the Northern hemisphere. It is the most important feline pathogen of the Anaplasma genus.  Wild small mammals are the natural reservoirs of infection.

Fig. 1. Presence of Anaplasma spp morulae (arrows) in neutrophils. Reprinted with permission from Adaszek et al., 2013.

Fig. 1. Presence of Anaplasma spp morulae (arrows) in neutrophils. Reprinted with permission from Adaszek et al., 2013.

Anaplasma platys replicates in mature platelets and is the agent of thrombocytotropic anaplasmosis, a disease well documented in dogs worldwide (Sainz et al., 2015).

Anaplasma bovis is responsible for a severe tick-borne disease in cattle and in 2012 was reported for the first time in cats in Japan (Sasaki et al., 2012). A novel, unclassified A. platys-like strain from cats was characterized in Sardinia (Italy). This strain, despite its tropism for platelets, is closely related to other Anaplasma spp. identified in ruminants (Zobba et al., 2015). ‘Candidatus Anaplasma amazonensis’ described in sloths from northern Brazil, was detected in the blood of two cats from the Minas Gerais state of Brazil (André et al., 2022). An A. platys-like strain detected in gray-pocket deer (Mazama gouazoubira) from Brazil was found in the blood from a cat of the São Paulo state of Brazil (André et al., 2022).

Ehrlichia canis is the agent of canine monocytotropic ehrlichiosis. This disease is described in tropical and temperate areas worldwide, with the exception of Australia. In endemic areas for the canine disease, feline infection is reported (Braga et al., 2012; Braga et al., 2021). In Brazil the possible existence of a new E. canis genotype infecting cats was supported based on ELISA antibody detection of anti-E. canis specific peptide antibodies (Braga et al., 2021).

Ehrlichia chaffeensis is the agent of human monocytotropic ehrlichiosis reported mainly in the USA where it was detected in ticks collected from cats (Amblyomma americanum) as well as dogs (Little et al., 2018).

The granulocytotropic Ehrlichia ewingii has been evidenced in dogs and humans in the Midwestern and Southern United States.

Another member of the Anaplasmataceae family that leads to neoehrlichiosis is Neoehrlichia mikurensis. This emerging tick-borne agent has been found mainly in immunocompromised patients, in ticks and rodents and also in dogs (Diniz et al., 2011; Hofmann-Lehmann et al., 2016), but so far not in cats. However, N. mikurensis has been detected in ticks collected from cats and infection may be underdiagnosed because diagnostic assays are not yet widely available (Kooyman et al., 2022).

The Rickettsiaceae family includes the spotted fever group (SFG) and the typhus group agents (Allison and Little, 2013). More than 20 species are included in the SFG of the Rickettsia genus, some of them being important human pathogens. Historically, the most important zoonotic agents are R. conorii (the cause of Mediterranean spotted fever) in the Old World, and R. rickettsii (the agent of Rocky Mountains spotted fever) in the Americas. However, molecular studies have increasingly focused on other rickettsial species that may be involved in human clinical disease. Rickettsia massiliae, for example, is now recognised as the most widely distributed Rickettsia species that affects humans, being found worldwide (Brouqui et al., 2007).

Rickettsia felis is a worldwide emerging flea-borne SFG human pathogen, frequently detected in Ctenocephalides felis, less often in other flea species (Brouqui et al., 2007; Abdullah et al., 2020).

Rickettsia typhi is a worldwide flea-borne rickettsia of the typhus group. It is the agent of murine or endemic typhus transmitted from rats by Xenopsylla fleas, or from cats to humans by C. felis, as well as to cats or wild animal reservoirs (Blanton et al., 2019).

Epidemiology

Prevalence

Anaplasma spp.

In Europe, feline antibody prevalence to A. phagocytophilum has been reported as 4.5-33.3% in Italy (Ebani and Bertelloni, 2014; Persichetti et al., 2016, 2018), 2.0-8.0% in Spain (Solano-Gallego et al., 2006; Ayllón et al., 2012), 16.2-23.0% in Germany (Hamel et al., 2012; Schäfer et al., 2022), 30.0% in Austria (Schäfer et al., 2022), 24.0% in Switzerland (Schäfer et al., 2022), and 22.1% in Sweden (Elfving et al., 2015). In the Americas, the prevalence was 1.8-38.0% in studies performed in the US (Magnarelli et al., 2005; Billeter et al., 2007; Hegarty et al., 2015) and 23.0% in Brazil (Pedrassani et al., 2019).

Anaplasma phagocytophilum DNA was amplified in blood samples from cats admitted to veterinary clinics in Germany (0.4-3.0%), Austria (8.0%), and Switzerland (10.0%) (Bergmann et al., 2015; Schäfer et al., 2022). Blood PCR positivity percentage for A. phagocytophilum was 0.33% in apparently healthy cats admitted for neutering in Brazil (Pedrassani et al., 2019), 0.9% in shelter cats from Korea (Lee et al., 2016), and 1.0% of anaemic cats in the US (Chan et al., 2021). The DNA of Anaplasma spp. closely related to A. phagocytophilum was detected in the blood of cats in Brazil (André et al., 2014, 2017).

Schäfer et al. (2022) reported the annual antibody and PCR prevalence of A. phagocytophilum in Germany. Antibody positivity increased from 8.0-12.0% of cats tested between 2008 and 2012 to 35.0-45.0% between 2018 and 2020. Results of blood PCR positivity increased from 0-2.0% between 2009 and 2013 to 2.0-10.0% between 2017 and 2020. Changes in the presence of vectors are much feared factors for these increases in positivity, however theymay be influenced also by an increased awareness of practitioners about feline anaplasmosis (Schäfer et al., 2022).

In Europe, feline A. platys infection has been detected by blood PCR analysis in Cyprus (0.6% of 174 samples tested) (Attipa et al., 2017) and in Turkey (30.5% of 167 samples analysed) (Muz et al., 2021). In the Americas, PCR positivity for A. platys was 0.4-1.0% in the US (Hegarty et al., 2015; Chan et al., 2021), 3.3% in Chile (Sacristán et al., 2019) and a case was reported in Brazil (Lima et al., 2010).

Anaplamsa bovis DNA has been detected in the blood of two feline immunodeficiency virus (FIV) positive cats from Japan (Sasaki et al., 2012). These were the only samples found to be positive out of 1764 samples tested from outdoor cats in 2008 throughout Japan (Sasaki et al., 2012). In Africa, one apparently healthy cat out of 102 tested in Angola was PCR positive in blood for A. bovis (Oliveira et al., 2018).

Ehrlichia spp.

In Europe, E. canis DNA has been detected by PCR in 5.4% (35/649) blood samples of cats from Portugal (Maia et al., 2014) and serum antibody positive cats were found in 9.9%-17.9% of tested samples in Spain (Aguirre et al., 2004; Ortuño et al., 2005; Solano-Gallego et al., 2006; Ayllón et al., 2012), and 6.4-16.2% of samples in Italy (Ebani and Bertelloni, 2014; Persichetti et al., 2016, 2018). In Germany, among 320 cats imported or travelling abroad, 40 were found antibody positive to E. canis (Schäfer et al., 2021).

In the Americas, E. canis DNA has been detected in the blood of three cats from the US (Breitschwerdt et al., 2002) and in 0.1% (Hegarty et al., 2015) and 1.0% (Chan et al., 2021) of tested cats in other US studies. Additionally, PCR positivity was obtained in 5.0% of cats in the Caribbean archipelago of Saint Kitts (Kelly et al., 2017). In Brazil studies have found variable rates of positivity, ranging from 0.5% to 20.0% (Oliveira et al., 2009; Braga et al., 2012, 2013, 2014; Guimarães et al., 2019; Pedrassani et al., 2019; André et al., 2015, 2022). In Africa, the blood samples of three of 102 apparently healthy cats (2.9%) from Angola were found to be PCR positive to E. canis (Oliveira et al., 2018). In the tropical island of Guam (a territory of US located in Micronesia in the Western pacific Ocean) the blood of a cat was found to be PCR positive for E. canis (Weaver at al., 2022). In Qatar cats, PCR positivity was 2.9% (Alho et al., 2017). Antibody positivity to E. canis has been reported in the US (0.7%), Brazil (5.5-26.4%), and Saint Kitts (10.0%) (Braga et al., 2012, 2021; Hegarty et al., 2015; Kelly et al., 2017; Guimarães et al., 2019; Pedrassani et al., 2019).

Ehrlichia chaffeensis and E. ewingii have been rarely found in cats in the US (Hegarty et al., 2015) and E. chaffeensis has been rarely reported in Brazil (Braga et al., 2012).

Rickettsia spp.

Feline infections caused by R. massiliae and R. conorii have been confirmed by both PCR and antibody testing in endemic areas of Spain and Portugal (Solano-Gallego et al., 2006; Alves et al., 2009; Vilhena et al., 2013; Segura et al., 2014), whereas cats seropositive for R. rickettsii have been reported in the US and Saint Kitts in West Indies (Case et al., 2006; Kelly et al., 2017). In a retrospective evaluation of cats tested in Germany between 2015 and 2020, 11.0% of cats had anti-Rickettsia spp. antibodies (Schäfer et al., 2022).

Just as in humans and dogs, co-infections with multiple vector-borne pathogens can occur in cats (Maia et al., 2014; Hegarty et al., 2015; Attipa et al., 2017; Oliveira et al., 2018; Schäfer et al., 2022; André et al., 2022). For instance, amongst stray cats from Northern Italy, blood PCR positivity for A. phagocytophilumEhrlichia spp. and Rickettsia spp. (17.7%, 5.4% and 31.9%, respectively) showed that 5.4% of tested cats were positive for both A. phagocytophilum and Rickettsia spp. and 0.8% were positive for all three pathogens (Spada et al., 2014). In Brazil, two cats with non specific signs were found to be blood PCR positive for Anaplasma spp., Ehrlichia spp., Cytauxzoon felis and “Candidatus Mycoplasma haemominutum” (André et al., 2017). Host co-infection can be caused by concurrent transmission from vectors carrying multiple pathogens (Noden et al., 2017; Calvani et al., 2020).

Transmission

The geographical distribution of AnaplasmaEhrlichia and Rickettsia pathogens overlaps with that of the competent vectors. In Europe, two tick species are mainly involved: Rhipicephalus sanguineus sensu lato (the brown dog tick or kennel tick), which is the main tick vector of E. canis and R. conorii (and suspected for A. platys); and Ixodes ricinus, the vector of A. phagocytophilum. Both species can transmit also other pathogens (Babesia spp., Borrelia spp.) as single or multiple infections, and both species are found also on cats (Jameson and Medlock, 2011; Claerebout et al., 2013; Pennisi et al., 2015a; Król et al., 2015; Duplan et al., 2018; Jongejan et al., 2019; Kooyman et al., 2022). In a large-scale survey performed in the UK evaluating ticks collected from cats for pathogen DNA by PCR, 0.9% of 540 ticks were positive for A. phagocytophilum DNA. Four positive samples were from I. ricinus ticks and one from a I. hexagonous tick (Duplan et al., 2018). In Canada exposure to A. phagocytophilumwas found in cats carrying infected Ixodes scapularis ticks (Duplaix et al., 2021). In Asia infection of ticks collected from cats was documented for E. canis in R. sanguineus (Indonesia, the Philippines) and A. platys in Ixodes spp. (Taiwan) (Nguyen et al., 2020). However, A. phagocytophilum and A. platys DNA were also detected in fleas collected from cats (Pawelczyk et al., 2019; Calvani et al., 2020).

Ixodes ricinus has a wide distribution, from the Mediterranean area to Scandinavian countries, and from Portugal to Ukraine (https://www.ecdc.europa.eu/en/publications-data/ixodes-ricinus-current-known-distribution-october-2023). In the Eastern part of Europe a closely related species, Ixodes persulcatus is found (Sainz et al., 2015). Ixodes hexagonus was reported in cats from the UK (Duplan et al., 2018) and the Netherlands (Kooyman et al., 2022).

Rhipicephalus sanguineus sensu lato is common in the Mediterranean basin; it is not indigenous in northern countries but it can hibernate sheltered in cracks of kennel structures, so the area of its distribution is expanding northwards.

Based on vector distribution, E. canis and A. platys are considered endemic in Mediterranean countries but are spreading northwards, whereas A. phagocytophilum is reported mainly in Northern and Central Europe (Sainz et al., 2015).

Rickettsia rickettsii and R. conorii are both transmitted by ticks, infect dogs and may cause an acute febrile clinical disease in dogs (Solano-Gallego et al., 2015). Less information is available about the effect of these agents in cats.

Similar rates of positivity to Ehrlichia spp., Anaplasma spp., and Rickettsia spp. were found in healthy cats as compared to those showing clinical signs (Spada et al., 2014). Blood transfusion consequently may be a non-vectorial mode of transmission for rickettsial agents in cats, as it is well known in dogs (Sainz et al., 2015).

Ctenocephalides felis is the vector and the recognised reservoir of R. felis, which is vertically transmitted to successive generations of fleas (Wedincamp and Foil, 2002). However, dogs can be considered a reservoir as well because they have prolonged rickettsiaemias without showing clinical or haematological manifestations, and maintain horizontal transmission from infected to uninfected fleas (Ng-Nguyen et al., 2020). Studies carried out in some parts of Europe have shown that R. felis infection rates of Ctenocephalides range from 2.8% in Albania (Silaghi et al., 2012) to 54.2% in Andalusia (Márquez et al., 2006).

Pathogenesis

Little information is available on the pathogenesis of rickettsial diseases in cats. A limited number of studies on experimental infections or exposure with A. phagocytophilum or R. felis in cats exist. The intraperitoneal experimental infection with A. phagocytophilum infected blood in a small number of cats resulted in mild disease with transient fever not associated with changes in appetite nor general appearance. However, a mild reduction in total leukocyte, neutrophil and lymphocyte counts, a marked reduction in PCV values, and transient increase of ALT and AST values, were detected (Foley et al., 2003). Anti-nuclear antibodies and increased expression of γIFN mRNA were also found in infected cats but they had normal antibody responses to feline herpesvirus and feline leukaemia virus vaccination two weeks post infection (p.i.). When experimental infection with A. phagocytophilum was performed in FIV infected cats, upregulation of IL-10 expression was observed instead of γIFN, but the clinical course of disease was similar (Foley et al., 2003). The experimental exposure of four cats with wild-caught adult Ixodes scapularis induced a subclinical dual infection with A. phagocytophilum and Borrelia burgdorferi with no abnormalities concerning general appearance, appetite, and body temperature (Lappin et al., 2015).

In two reported cases of A. platys infection, the pathogenic role of the organism was not clearly established (Lima et al., 2010; Qurollo et al., 2014). One of the cats was diagnosed with a multiple myeloma, and coinfections with Bartonella henselaeB. koehlerae and ‘Ca. M. haemominutum’ (Qurollo et al., 2014). In this case, immunosuppression due to the severe monoclonal gammopathy could have been responsible for increased susceptibility to the co-infections.

Experimental subcutaneous inoculation of cats with a canine strain of E. canis was not successful and the pathogenesis of feline monocytotropic ehrlichiosis in cats is not known (Lappin and Breitschwerdt, 2012).

Cats are susceptible to R. felis infection and seroconvert after exposure to infected fleas. In rare cases, R. felis DNA can be amplified also from the skin or gingiva of cats whilst blood PCR testing is negative (Lappin and Hawley, 2009). It is unknown whether R. felis is present in other tissues of seropositive cats and whether it should be considered to be a feline pathogen. A short-term bacteraemia does occur in cats infected by R. felis but blood PCR testing is usually negative in antibody positive cats (Wedincamp and Foil, 2000; Hawley et al., 2007; Segura et al., 2014; Persichetti et al., 2016).

Clinical signs

In naturally exposed cats, clinical signs of feline granulocytotropic anaplasmosis are usually reported soon after tick infestation. They are mostly non-specific and consist of fever, anorexia, lethargy, conjunctivitis, and dehydration (Schäfer and Kohn, 2020). Lymphadenomegaly, lameness and swollen joints, epistaxis, and pain on abdominal palpation were less frequently reported (Bjöersdorff et al., 1999; Tarello, 2005; Adaszek et al., 2013; Savidge et al., 2016; Schäfer et al., 2022). The clinical course is usually short and not severe, and abnormalities resolve quickly, particularly when antibiotic treatment is given.

In Brazil, a natural infection with A. platys was found associated with anorexia and lethargy in a cat with a concurrent urinary infection (Lima et al., 2010).

Cats with monocytotropic ehrlichiosis manifest non-specific signs such as fever, anorexia and lethargy, but more rarely hyperesthesia, joint pain, pale mucous membranes, lymph node and spleen enlargement, and haemorrhagic diathesis (petechiae, vitreous haemorrhage) (Lappin and Breitschwerdt, 2012).

In US a case-control study comparing Rickettsia species positivity in cats with and without fever found more cats seropositive for R. felis and R. rickettsii among the cats with fever, but the difference was not statistically significant (Bayliss et al., 2009).

Laboratory and diagnostic imaging findings

Laboratory changes

Clinicopathological abnormalities reported in cats with granulocyotropic anaplasmosis include complete blood count (CBC) abnormalities as mild or moderate thrombocytopenia, anaemia, lymphopenia, and eosinopenia (Bjöersdorff et al., 1999; Lappin et al., 2004; Schaarschmidt-Kiener et al., 2009; Heikkilä et al., 2010; Adaszek et al., 2013; Savidge et al., 2016; Schäfer et al., 2022). However, in 13 cases with no known comorbidities, the CBC of five cats showed leukocytosis and in one case a severe haemolytic anaemia was observed (Schäfer et al., 2022). A transient lymphopenia was the only CBC abnormality detected during a 13 weeks of observation after an experimental exposure of four cats with wild-caught adult Ixodes scapularis (Lappin et al., 2015). In a few cases without known comorbidities biochemical investigations were available, and changes included increased values of serum proteins (3/10), globulins (2/9), ALT (1/8), and bilirubin (2/8) (Schäfer et al., 2022).

Mild thrombocytopenia was reported in a cat with A. platys infection and a concurrent urinary tract infection (Lima et al., 2010). One month later the platelet count was within the reference range and leukocytosis was found.

Clinicopathological changes seen in cats with monocytic ehrlichiosis included non-regenerative anaemia, thrombocytopenia, pancytopenia and increased or decreased white cell counts (Lappin and Breitschwerdt, 2012). Bone marrow hypoplasia was found in cats with pancytopenia or anaemia and thrombocytopenia on CBC (Breitschwerdt et al., 2002). The most consistent biochemical abnormality seen with feline monocytotropic ehrlichiosis was hyperproteinaemia and polyclonal or monoclonal gammopathy, which is also typical of the chronic course of canine monocytotropic ehrlichiosis (Lappin and Breitschwerdt, 2012). Anti-nuclear antibodies were found in some cats and neutrophilic polyarthritis was diagnosed in a cat with joint signs (Breitschwerdt et al., 2002).

In a study conducted in Brazil, anaemia was found associated in cats with antibody positivity to E. canis (Guimarães et al., 2019). Another study, however, which explored the associations between Ehrlichia spp. or A. phagocytophilum infections and anaemia, did not detect any significant associations (Ishak et al., 2006).

Diagnostic imaging findings

Little information is available on diagnostic imaging findings in feline Rickettsial infections. Splenomegaly was documented by abdominal imaging in three out of 13 cats with granulocytotropic anaplasmosis with no known comorbidities (Schäfer et al., 2022).

Abdominal ultrasound evaluation was performed at diagnosis in a cat with A. platys and no abnormality was reported (Lima et al., 2010).

Diagnosis

The clinical suspicion for Rickettsial diseases mostly arises in cases of a febrile syndrome affecting cats exposed to ticks and fleas in endemic areas, especially stray or outdoor pet cats not protected by the regular use of appropriate ectoparasiticides (Lappin et al., 2020a, 2020b).

Detection of the infectious agent

Blood or buffy-coat smear evaluation may provide a cytological diagnosis of infections with Ehrlichia and Anaplasma spp. In general, intracytoplasmic inclusion bodies are more frequently found in granulocytotropic anaplasmosis than in monocytotropic ehrlichiosis and in animals with fever. Anaplasma phagocytophylum inclusion bodies are found in 1-24% of circulating neutrophils in cats with natural granulocytotropic anaplasmosis. In experimentally infected cats they appear 7-9 days p.i. (Foley et al., 2003) or over the first 10 weeks after tick infestation (Lappin et al., 2015). After antibiotic therapy they are no longer visible (Bjöersdorff et al., 1999; Heikkilä et al., 2010; Lappin et al., 2015). With A. platys, bacteraemia is cyclical in dogs at 1 to 2-week intervals, with a higher percentage of circulating infected platelets occurring during the initial cycles (Harvey et al., 1978), but no information is available in cats.

Blood PCR analysis is a sensitive and specific method for confirming diagnosis at the onset of acute clinical signs when antibody testing is usually still negative (Foley et al., 2003; Lappin et al., 2015). Because of overlapping clinical signs, the use of genus-inclusive primers for EhrlichiaAnaplasma and Rickettsia spp. genera in PCRs has been suggested as best practice, followed by sequencing of any resulting PCR products to determine the infecting species (Allison and Little, 2013). However, a study demonstrated that some genus-specific PCRs also detect Pseudomonas sequences and may lead to false positive results that may only be recognized after sequencing analysis (Hofmann-Lehmann et al., 2016). Alternatively, the use of species-specific real-time TaqMan assays may be faster and more sensitive options for the molecular detection of rickettsaemia.

Blood samples for microscopic detection or PCR should be collected prior to the initiation of antibiotic treatment.

A splenic aspirate was performed in one cat with granulocytic anaplasmosis and splenomegaly. The cytological evaluation showed reactive hyperplasia of the white pulp, pyogranulomatous inflammation and morulae in neutrophils (Schäfer et al., 2022). A prospective post-mortem investigation of 37 cats subjected to necropsy evaluated the occurrence of the Anaplasma spp. and Ehrlichia spp. DNA in different tissues such as spleen, bone marrow, blood clot, and hair (Balboni et al., 2021). Interestingly, positive results were obtained from spleen (one cat) and hair (two cats) samples, and none of the cats was positive in bone marrow nor blood (Balboni et al., 2021).

Detection of antibodies

Antibodies to rickettsial infections can be detected by immunofluorescence (IF) testing and ELISA. Cross-reaction is possible between A. phagocytophilum and A. platys but not with E. canis, although E. canis can cross react with other Ehrlichia spp. Rapid in-house ELISAs are available for detecting canine antibodies against A. phagocytophilum. These ELISAs were used in feline infection cases, comparing results with a commercial IF assay, but discrepancies were found (Hegarty et al., 2015).

Antibodies against A. phagocytophilum were detected in an experimental study within 14 days p.i. and seroconversion also occurs in natural infections, even in antibiotic treated cats (Foley et al., 2003). In cats experimentally exposed to infected ticks, antibodies against A. phagocytophilum appeared 2-6 weeks after infestation (Lappin et al., 2015). In the case of a positive IF test, a 4-fold increase of the titre over about four weeks is needed to confirm the acute course of the infection (Bjöersdorff et al., 1999; Foley et al., 2003; Lappin et al., 2004; Heikkilä et al., 2010). Moreover, some cats testing positive to E. canis by PCR were found to be antibody negative despite the advanced course of their disease, suggesting that a negative antibody test does not exclude the diagnosis (Breitschwerdt et al., 2002). When possible, both serological and blood PCR test should be performed in cats with compatible clinical signs.

Treatment

There are no controlled studies evaluating the efficacy of drugs used for treating rickettsial diseases in cats. However, doxycycline is considered the first choice antibiotic administered at 10 mg/kg orally q24h (or 5 mg/kg orally q12h) for 28 days. Available formulations of doxycycline vary but care must be taken with the administration of doxycycline hyclate tablets due to the risk of oesophagitis occurring with their permanence in the oesophagus after swallowing; oral administration should be followed by food and/or water to ensure passage of the tablet into the stomach.

In cases testing negative by microscopy, PCR or antibody testing, or when results of diagnostic tests are pending, but where there is a strong clinical suspicion of rickettsial disease, treatment should be initiated soon after blood collection to prevent the potential of rapid progression of clinical disease.

Management of infected patients

There is no evidence of the efficacy of antibiotic treatment for clearing infection in clinically healthy cats; therefore doxycycline or other antibiotics should not be given in these cases.

Prognosis

Clinical improvement is seen in the first 24-48 hours unless comorbidities or co-infections not susceptible to doxycycline are present, such as protozoal vector-borne agents, or if other complications develop such as severe bleeding (Savidge et al., 2016; Schäfer et al., 2022). Animals generally respond well to treatment but may remain persistently infected. Three cats diagnosed with granulocytotropic anaplasmosis (blood PCR positive) and treated with doxycycline for two or three weeks, had a clinical recurrence and tested again positive for A. phagocytophilum DNA at four and five weeks and two years, respectively, after the end of treatment (Schäfer et al., 2022). Persisting infections or reinfections may therefore occur after doxycycline treatment.

Vaccination

No vaccine is available for preventing disease caused by Rickettsiales in humans and animals.

Prevention

As vectors are the main routes of transmission of rickettsial infections, regular treatment with appropriate topical (spot ons, collars) or oral ectoparasiticides may protect cats from becoming infected, as it is well recognised in dogs.

In endemic areas, blood donors should be tested for rickettsial blood-borne infections to confirm they are negative before being used as donors (Pennisi et al., 2015b).

Zoonotic risk

Rickettsial pathogens are transmitted to humans by competent vectors. Infected cats, as well as dogs, are “sentinels” of the presence of rickettsial pathogens in ticks and fleas in a given geographical area and they signal a risk for people exposed to vectors (Król et al., 2015; Persichetti et al., 2016; Jongejan et al., 2019; Kooyman et al., 2022). Regular application of ectoparasiticides to pets reduces the risk of exposure of humans to vectors of rickettsial agents.

Direct contact with cat saliva should be avoided because of the potential contamination by R. felis as well as by other zoonotic pathogens.

Acknowledgement

ABCD Europe gratefully acknowledges the support of Boehringer Ingelheim (the founding sponsor of the ABCD), Virbac and IDEXX GmbH.

References

Abdullah S, Lait P, Helps C, Newbury H, Wall R (2020): The prevalence of Rickettsia felis DNA in fleas collected from cats and dogs in the UK. Vet Parasitol 282, 109143.

Adaszek L, Górna M, Skrzypczak M, Buczek K, Balicki I, Winiarczyk S (2013): Three clinical cases of Anaplasma phagocytophilum infection in cats in Poland. J Feline Med Surg 15, 333-337.

Aguirre E, Tesouro MA, Amusatequi I, Rodríquez-Franco F, Sainz A (2004): Assessment of feline ehrlichiosis in central Spain using serology and a polymerase chain reaction technique. Ann N Y Acad Sci 1026, 103-105.

Alho AM, Lima C, Latrofa MS, Colella V, Ravagnan S, Capelli G, Madeira de Carvalho L, Cardoso L, Otranto D (2017): Molecular detection of vector-borne pathogens in dogs and cats from Qatar. Parasit Vectors 10, 298.

Allison RW, Little SE (2013): Diagnosis of rickettsial diseases in dogs and cats. Vet Clin Pathol 42, 127-144.

Alves AS, Milhano N, Santos-Silva M, Santos AS, Vilhena M, de Sousa R (2009): Evidence of Bartonella spp., Rickettsia spp. and Anaplasma phagocytophilum in domestic, shelter and stray cat blood and fleas, Portugal. Clin Microbiol Infect 15 (S2), 1-3.

André MR, Baccarim Denardi NC, Marques de Sousa KC, Gonçalves LR, Henrique PC, Grosse Rossi Ontivero CR, Lima Gonzalez IH, Cabral Nery CV, Fernandes Chagas CR, Monticelli C, Alexandre de Santis AC, Machado RZ (2014): Arthropod-borne pathogens circulating in free-roaming cats in zoo environment in Brazil. Ticks Tick Borne Dis 5, 545-551.

André MR, Calchi AC, Furquim MEC, de Andrade I, Arantes PVC, de Melo Lopes LC, Demarchi IKLdN, Figueredo MAP, de Paula Lima CA, Machado RZ (2022): Molecular detection of tick-borne agents in cats from Southeastern and Northern Brazil. Pathogens 11, 106.

André MR, Filgueira KD, Calchi AC, de Sousa KCM, Gonçalves LR, Medeiros VB, Ximenes PA, Lelis ICNG, de Meireles MVN, Machado RZ (2017): Co-infection with arthropod-borne pathogens in domestic cats. Braz J Vet Parasitol 26, 525-531.

André MR, Herrera HM, Fernandes Sde J, de Sousa KC, Goncalves LR, Domingos IH, de Macedo GC, Machado RZ (2015): Tick-borne agents in domesticated and stray cats from the city of Campo Grande, state of Mato Grosso do Sul, Midwestern Brazil. Ticks Tick Borne Dis 6: 779-786.

Attipa C, Papasouliotis K, Solano-Gallego L, Baneth G, Nachum-Biala Y, Sarvani E, Knowles TG, Mengi S, Morris D, Helps C, Tasker S (2017): Prevalence study and risk factor analysis of selected bacterial, protozoal and viral, including vector-borne, pathogens in cats from Cyprus. Parasit Vectors 10, 130.

Ayllón T, Diniz PPVP, Breitschwerdt EB, Villaescusa A, Rodríguez-Franco F, Sainz A (2012): Vector-borne diseases in client-owned and stray cats from Madrid, Spain. Vector-borne and zoonotic diseases 12, 143-149.

Balboni A, Urbani L, Morini M, Dondi F, Battilani M (2021): Molecular detection of Anaplasma phagocytophilum in hair and spleen of cats revealed a possible underestimation of feline vector-borne pathogens. Res Vet Science 137, 144-149.

Bayliss D, Morris AK, Horta MC, Labruna MB, Radecki SV, Hawley JR, Brewer MM, Lappin MR (2009): Prevalence of Rickettsia species antibodies and Rickettsia species DNA in the blood of cats with and without fever. J Feline Med Surg 11: 266-270.

Blanton LS, Vohra RF, Fistein L, Quade B, Walker DH, Bouyer DH (2019): Rickettsiae within the fleas of feral cats. Vector Borne Zoonotic Dis 19, 647-651.

Bergmann MEnglert TStuetzer BHawley JRLappin MRHartmann K (2015): Prevalence of selected rickettsial infections in cats in Southern Germany. Comp Immunol Microbiol Infect Dis 42, 33-36.

Billeter SA, Spencer JA, Griffin B, Dykstra CC, Blagburn BL (2007): Prevalence of Anaplasma phagocytophilum in domestic felines in the United States. Vet Parasitol 147, 194-198.

Bjöersdorff A, Svendenius L, Owens JH, Massung RF (1999): Feline granulocytic ehrlichiosis – a report of a new clinical entity and characterization of the infectious agent. J Small Anim Pract 40, 20-24.

Braga M, André MR, Freschi CR, Teixeira MCA, Machado RZ (2012): Molecular and serological detection of Ehrlichia spp. in cats on São Luís island, Maranhão, Brazil. Rev Bras Parasitol Vet 21, 37-41.

Braga IA, Santos LG, Melo AL, Jaune FW, Ziliani TF, Girardi A, de Aguiar DM (2013): Hematological values associated to the serological and molecular diagnostic in cats suspected of Ehrlichia canis infection. Rev Bras Parasitol Vet 22, 470-474.

Braga IA, Santos LG, Ramos DG, Melo AL, Mestre GL, de Aguiar DM (2014): Detection of Ehrlichia canis in domestic cats in the central-western region of Brazil. Brazilian Journal of Microbiology 45, 641-645.

Braga IA, Taques IIGG, Grontoski EC, de Oliveira Dias IS, Pereira NA, de Souza Ramos DG, Dantas-Torre F, de Aguiar DM (2021): Exposure of domestic cats to distinct Ehrlichia canis TRP genotypes. Vet Sci 8, 310.

Breitschwerdt EB, Abrams-Ogg AC, Lappin MR, Bienzle D, Hancock SI, Cowan SM, Clooten JK, Hegarty BC, Hawkins EC (2002): Molecular evidence supporting Ehrlichia canis-like infection in cats. J Vet Intern Med 16, 642-649.

Brouqui P, Parola P, Fournier PE, Raoult D (2007): Spotted fever rickettsioses in southern and eastern Europe. FEMS Immunol Med Microbiol 49, 2-12.

Calvani NED, Bell L, Carney A, De La Fuente C, Stragliotto T, Tunstall M, Šlapeta J (2020): The molecular identity of fleas (Siphonaptera) carryin Rickettsia felisBartonella clarridgeiae and Bartonella rochalimae from dogs and cats in Northern Laos. Heliyon 6, e04385.

Case JB, Chomel B, Nicholson W, Foley JE (2006): Serological survey of vector-borne zoonotic pathogens in pet cats and cats from animal shelters and feral colonies. J Feline Med Surg 8, 111-117.

Chan PK, Hawley JR, Lappin MR (2021): Evaluation of the role of Babesia species and Cytauxzoon felis in feline anemia cases in Colorado, USA. J Feline Med Surg Open Reports doi: 10.1177/20551169211024967. eCollection 2021 Jan-Jun.

Claerebout ELosson BCochez CCasaert SDalemans ACDe Cat AMadder MSaegerman CHeyman PLempereur L (2013): Ticks and associated pathogens collected from dogs and cats in Belgium. Parasit Vectors 6, 183.

Diniz PP, Schulz BS, Hartmann K, Breitschwerdt EB (2011): “Candidatus Neoehrlichia mikurensis” infection in a dog from Germany. J Clin Microbiol 49, 2059–2062.

Duplaix L, Wagner V, Gasmi S, Lindsay LR, Dibernardo A, Thivierge K, Fernandez-Prada C, Arsenault J (2021): Exposure to tick-borne pathogens in cats and dogs infested with Ixodes scapularis in Quebec: an 8-year surveillance study. Front Vet Sci 8, 696815.

Duplan F, Davies S, Filler S, Abdullah S, Keyte S, Newbury H, Helps C, Wall R, Tasker S (2018): Anaplasma phagocytophilumBartonella spp., haemoplasma species and Hepatozoon spp. in ticks infesting cats: a large-scale survey. Parasit Vectors 11, 201.

Ebani VV, Bertelloni F (2014): Serological evidence of exposure to Ehrlichia canis and Anaplasma phagocytophilum in Central Italian healthy domestic cats. Ticks and Tick-borne Diseases 5, 668-671.

ECDC (European Centre for Disease Prevention and Control): (http://ecdc.europa.eu/en/healthtopics/vectors/vector-maps/Pages/VBORNET-maps-tick-species.aspx

Elfving K, Malmsten J, Dalin AM, Nilsson K (2015): Serological and molecular prevalence of Rickettsia helvetica and Anaplasma phagocytophilum in wild cervids and domestic mammals in the central parts of Sweden. Vector Borne Zoonotic Dis 15, 529-534.

Foley JE, Leutenegger CM, Dumler JS, Pedersen NC, Madigan JE (2003): Evidence for modulated immune response to Anaplasma phagocytophila sensu lato in cats with FIV-induced immunosuppression. Comp Immunol Microbiol Infect Dis 26, 103-113.

Guimarães A, Macedo Raimundo J, Braul Rodrigues R, Peckle Peixoto M, Azevedo Santos H, André MR, Machado RZ, Divan Baldani C (2019): Ehrlichia spp. infection in domestic cats from Rio de Janeiro State, southeast Brazil. Braz J Vet Parasitol 28, 180-185.

Hamel D, Bondarenko A, Silaghi C, Nolte I, Pfister K (2012): Seroprevalence and bacteremia of Anaplasma phagocytophilum in cats from Bavaria and Lower Saxony (Germany). Berl Munch Tierarztl Wochenschr 125, 163-167.

Harvey JW, Simpson CF, Gaskin JM (1978): Cyclic thrombocytopenia induced by a Rickettsia-like agent in dogs. J Infect Dis 137, 182-188.

Hawley JR, Shaw SE, Lappin MR (2007): Prevalence of Rickettsia felis DNA in the blood of cats and their fleas in the United States. J Feline Med Surg 9, 258-262.

Hegarty BC, Qurollo BA, Thomas B, Park K, Chandrashekar R, Beall MJ, Thatcher B, Breitschwerdt EB (2015): Serological and molecular analysis of feline vector-borne anaplasmosis and ehrlichiosis using species-specific peptides and PCR. Parasit Vectors 8, 320.

Heikkilä HM, Bondarenko A, Mihalkov A, Pfister K, Spillmann T (2010): Anaplasma phagocytophilum infection in a domestic cat in Finland: case report. Acta Vet Scand 52, 62.

Hofmann-Lehmann R, Wagmann N, Meli ML, Riond B, Novacco M, Joekel D, Gentilini F, Marsilio F, Pennisi MG, Lloret A, Carrapiço T, Boretti FS (2016): Detection of ‘Candidatus Neoehrlichia mikurensis’ and other Anaplasmataceae and Rickettsiaceae in Canidae in Switzerland and Mediterranean countries. Schweiz Arch Tierheilkd 158, 691-700.

Ishak AM, Radecki S, Lappin MR (2006): Prevalence of Mycoplasma haemofelis, “Candidatus Mycoplasma haemominutum”, Bartonella species, Ehrlichia species, and Anaplasma phagocytophilum DNA in the blood of cats with anemia. J Feline Med Surg 9, 1-7.

Jameson LJMedlock JM (2011): Tick surveillance in Great BritainVector Borne Zoonotic Dis 11(4), 403-412.

Jongejan F, de Jong S, Voskuilen T, van den Heuvel L, Bouman R, Heesen H, Ijzermans C, Berger L (2019): “Tekescanner”: a novel smartphone application for companion animal owners and veterinarians to engage in tick and tick-borne surveillance in the Netherlands. Parasit Vectors 12, 116.

Kelly PJ, Köster L, Li J, Zhang J, Huang K, Brandford GC, Marchi S, Vandenplas M, Wang C (2017): Survey of vector-borne agents in feral cats and first report of Babesia gibsoni in cats on St Kitts, West Indies. Vet Research 13, 331.

Kooyman FNJ, Zweerus H, Nijsse ER, Jongejan F, Wagenaar JA, Broens EM (2022): Monitoring of ticks and their pathogens from companion animals by the “tekescanner” application in the Netherlands. Parasitology Res doi: 10.1007/s00436-022-07518-3

Król N, Obiegala A, Pfeffer M, Lonc E, Kiewra D (2015): Detection of selected pathogens in ticks collected from cats and dogs in the Wrocław Agglomeration, South-West Poland. Parasit Vectors 9, 351.

Lappin MR, Breitschwerdt ER (2012): Ehrlichia spp. infection (feline monocytotropic ehrlichiosis). In Greene CE: Infectious diseases of the dog and cat. Elsevier, St Louis, Missouri, p. 238-241.

Lappin MR, Breitschwerdt EB, Jensen WA, Dunnigan B, Rha JY, Williams CR, Brewer M, Fall M (2004): Molecular and serological evidence of Anaplasma phagocytophilum infection in cats in North America. J Am Vet Med Assoc 225, 893-896.

Lappin MR, Chandrashekar R, Stillman B, Liu J, Mather TN (2015): Evidence of Anaplasma phagocytophilum and Borrelia burgdorferi infection in cats after exposure to wild-caught adult Ixodes scapularis. J Vet Diagn Invest 27, 522-525.

Lappin MR, Hawley J (2009): Presence of Bartonella species and Rickettsia species DNA in the blood, oral cavity, skin and claw beds of cats in the United States. Vet Dermatol 20, 509-514.

Lappin MR, Tasker S, Roura X (2020a): Role of vector-borne pathogens in the development of fever in cats: 1. Flea-associated diseases. J Feline Med Surg 22, 31-39.

Lappin MR, Tasker S, Roura X (2020b): Role of vector-borne pathogens in the development of fever in cats: 2. Tick- and sandfly-associated diseases. J Feline Med Surg 22, 41-48.

Lee S-H, VanBik D, Kim N-H, Park S-J, Kwon O-D, Kim T-H, Kwak D (2016): First molecular detection and genetic analysis of Anaplasma phagocytophilum in shelter cats in Seoul, Korea. Infection, Genetics and Evolution 46, 71-73.

Lima MLF, Soares PT, Ramos CAN, Araújo FR, Ramos RAN, Souza IIF, Faustino MAG, Alves LCA (2010): Molecular detection of Anaplasma platys in a naturally-infected cat in Brazil. Brazilian Journal of Microbiology 41, 381-385.

Little S, Barrett AW, Nagamori Y, Herrin BH, Normile D, Heaney K, Armstrong R (2018): Ticks from cats in the United States: patterns of infestation and infection with pathogens. Vet Parasitol 257, 15-20.

Magnarelli LA, Bushmich SL, IJdo JW, Fikrig E (2005): Seroprevalence of antibodies against Borrelia burgdorferi and Anaplasma phagocytophilum in cats. Am J Vet Res 66, 1895-1899.

Maia C, Ramos C, Coimbra M, Bastos F, Martins A, Pinto P, Nunes M, Vieira ML, Cardos L, Campino L (2014): Bacterial and protozoal agents of feline vector-borne diseases in domestic and stray cats from southern Portugal. Parasite & Vectors 7, 115.

Márquez FJ, Muniain MA, Rodríquez-Liebana JJ, Del Toro MD, Bernabeu-Wittel M, Pachón AJ (2006): Incidence and distribution pattern of Rickettsia felis in peridomestic fleas from Andalusia, Southeast Spain. Ann N Y Acad Sci 1078, 344-346.

Muz MN, Erat S, Mumcuoglu KY (2021): Protozoan and microbial pathogens of house cats in the province of Tekirdag in Western Turkey. Pathogens 10, 1114.

Nguyen V-L, Colella V, Greco G, Fang F, Nurcahyo W, Hadi UK, Venturina V, Tong KBY, Tsai Y-L, Taweethavonsawat P, Tiwananthagorn S, Tangtrongsup S, Le TQ, Bui KL, Do T, Watanabe M, Rani PAMA, Dantas-Torres F, Halos L, Beugnet F, Otranto D (2020): Molecular detection of pathogens in ticks and fleas collected from companion dogs and cats in East and Southeast Asia. Parasit Vectors 13, 420.

Ng-Nguyen D, Hii S-F, Hoang M-TT, Nguyen V-AT, Rees R, Stenos J, Traub RJ (2020): Domestic dogs are mammalian reservoir for the emerging zoonosis flea-borne spotted fever, caused by Rickettsia felis. Scientific Reports 10, 4151.

Noden BH, Davidson S, Smith JL, Williams F (2017): Rickettsia felis in fleas from Catalonia (Northeast Spain). J Med Entomol 54, 1093-1097.

Oliveira AC, Luz MF, Granada S, Vilhena H, Nachum-Biala Y, Lopes AP, Cardoso L, Baneth G (2018): Molecular detection of Anaplasma bovisEhrlichia canis and Hepatozoon felis in cats from Luanda, Angola. Parasit Vectors 11, 167.

Oliveira LS, Mourão LC, Oliveira KA, Agostini M, Oliveira AC, Almeida MR, Fietto LR, Conceição LG, Filho JDR, Galvão MAM, Mafra C (2009): Molecular detection of Ehrlichia canis in cats in Brazil. Clin Microbiol Infect 15(S2), 53-54.

Ortuño A, Gauss CB, García F, Gutierrez JF (2005): Serological evidence of Ehrlichia spp. exposure in cats from northeastern Spain. J Vet B Infect Dis Vet Public Health 52, 246-248.

Pawelczyk O, Asman M, Solarz K (2019): The molecular detection of Anaplasma phagocytophilum and Rickettsia spp. in cat and dog fleas collected from companion animals. Folia Parasitologica 66, 020.

Pedrassani D, Biolchi J, Gonçalves LR, Mendes NS, de Souza Zanatto DC, Calchi AC, Zacaris Machado R, André MR (2019): Molecular detection of vector-borne agents in cats in Southern Brazil. Braz J Vet Parasitol 28, 632-643.

Pennisi MG, Hartmann K, Addie DD, Lutz H, Gruffydd-Jones T, Boucraut-Baralon C, Egberink H, Frymus T, Horzinek MC, Hosie MJ, Lloret A, Marsilio F, Radford A, Thiry E, Truyen U, Möstl K (2015b): Blood transfusion in cats. ABCD guidelines for minimising risks of infectious iatrogenic complications. J Feline Med Surg 17, 589-593.

Pennisi MG, Persichetti MF, Serrano L, Altet L, Reale S, Gulotta L, Solano-Gallego L (2015a): Ticks and associated pathogens collected from cats in Sicily and Calabria (Italy). Parasit Vectors 8, 512.

Persichetti MF, Pennisi MG, Vullo A, Masucci M, Migliazzo A, Solano-Gallego L (2018): Clinical evaluation of outdoor cats exposed to ectoparasites and associated risk for vector-borne infections in southern Italy. Parsit Vectors 11, 136.

Persichetti MF, Solano-Gallego L, Serrano L, Altet L, Reale S, Masucci M, Pennisi MG (2016): Detection of vector-borne pathogens in cats and their ectoparasites in southern Italy. Parasit Vectors 9, 247.

Qurollo BA, Balakrishnan N, Cannon CZ, Maggi RG, Breitschwerdt ER (2014): Co-infection with Anaplasma platys, Bartonella henselae, Bartonella koehlerae and ‘Candidatus Mycoplasma haemominutum’ in a cat diagnosed with splenic plasmocytosis and multiple myeloma. J Feline Med Surg 16, 713-720.

Sacristán I, Sieg M, Acuña F, Aguilar E, García S, López MJ, Cevidanes A, Hidalgo-Hermoso E, Cabello J, Vahlenkamp TW, Millán J, Poulin E, Napolitano C (2019): Molecular and serological survey of carnivore pathogens in free-roaming domestic cats of rural communities in southern Chile. J Vet Med Sci 81, 1740-1748.

Sainz A, Roura X, Miró G, Estrada-Peña A, Kohn B, Harrus S, Solano-Gallego L (2015): Guideline for veterinary practitioners on canine ehrlichiosis and anaplasmosis in Europe. Parasit Vectors 8, 75.

Sasaki H, Ichikawa Y, Sakata Y, Endo Y, Nishigaki K, Matsumoto K, Inokuma H (2012): Molecular survey of Rickettsia, Ehrlichia, and Anaplasma infection of domestic cats in Japan. Ticks and Tick-borne Diseases 3, 307-310.

Savidge C, Ewing P, Andrews J, Aucoin D, Lappin MR, Moroff S (2016): Anaplasma phagocytophilum infection of domestic cats: 16 cases from northeastern USA. J Feline Med Surg 18, 85-91.

Schaarschmidt-Kiener D, Graf F, von Loewenich FD, Müller W (2009): Anaplasma phagocytophilum infection in a cat in Switzerland. Schweiz Arch Tierheilkd 151, 336-341.

Schäfer I, Kohn B (2020): Anaplasma phagocytophilum infection in cats. A literature review to raise clinical awareness. J Feline Med Surg 22, 428-441.

Schäfer I, Kohn B, Müller E (2022): Anaplasma phagocytophilum in domestic cats from Germany, Austria and Switzerland and clinical/laboratory findings in 18 PCR-positive cats (2008-2020). J Feline Med Surg 24, 290-297.

Schäfer I, Kohn B, Volkmann M, Müller E (2021). Retrospective evaluation of vector-borne pathogens in cats living in Germany (2012-2020). Parasit Vectors 14, 123.

Segura F, Pons I, Miret J, Pla J, Ortuño A, Nogueras M-M (2014): The role of cats in the eco-epidemiology of spotted fever group diseases. Parasit Vectors 7, 353.

Silaghi C, Knaus M, Rapti D, Kusi I, Shukullari E, Hamel D, Pfister K (2012): Survey of Toxoplasma gondii and Neospora caninum, haemotropic mycoplasmas and other arthropod-borne pathogens in cats from Albania. Parasit Vectors 7, 62.

Solano-Gallego L, Caprì A, Pennisi MG, Caldin M, Furlanello T, Trotta M (2015): Acute febrile illness is associated with Rickettsia spp infection in dogs. Parasit Vectors 8, 216.

Solano-Gallego L, Hegarty B, Espada Y, Llull J, Breitschwerdt E (2006): Serological and molecular evidence of exposure to arthropod-borne organisms in cats from northeastern Spain. Vet Microbiol 118, 274-277.

Spada E, Proverbio D, Galluzzo P, Della Pepa A, Perego R, Bagnagatti De Giorgi G, Ferro E (2014): Molecular study on selected vector-borne infections in urban stray colony cats in northern Italy. J Feline Med Surg 16, 684-688.

Tarello W (2005): Microscopic and clinical evidence for Anaplasma (Ehrlichiaphagocytophilum infection in Italian cats. Vet Rec 156, 772-774.

Vilhena H, Martinez-Díaz V, Cardoso L, Vieira L, Altet L, Francino O, Pastor J, Silvestre-Ferreira AC (2013): Feline vector-borne pathogens in the north and centre of Portugal. Parasit Vectors 6, 99.

Weaver G, Anderson N, Garrett K, Thompson AT, Yabsley MJ (2022): Domestic animals, wild pigs, and off-host environmental sampling in Guam, USA. Front Vet Sci 8, 803424.

Wedincamp J JrFoil LD (2000): Infection and seroconversion of cats exposed to cat fleas (Ctenocephalides felis Bouché) infected with Rickettsia felisJ Vector Ecol 25, 123-126.

Wedincamp J Jr, Foil LD (2002): Vertical transmission of Rickettsia felis in the cat flea (Ctenocephalides felis Bouché). J Vector Ecol 27, 96-101.

Zobba R, Anfossi AG, Visco S, Sotgiu F, Dedola F, Pinna Parpaglia ML, Battilani M, Pittau M, Alberti A (2015): Cell tropism and molecular epidemiology of Anaplasma platys-like strains in cats. Ticks Tick Borne Dis 6, 272-280.