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

Detection of Anaplasma spp. and Ehrlichia spp. in dogs from a veterinary teaching hospital in Italy: a retrospective study 2012-2020

Anaplasma phagocytophilum, Anaplasma platys and Ehrlichia canis, responsible of diseases in dogs, are tick-borne pathogens with a proven or potential zoonotic role that have shown increasing prevalence worldwide. The aims of this retrospective study were to assess the frequency of Anaplasma spp. and Ehrlichia spp. exposure in dogs tested in a veterinary teaching hospital in Italy over a 9-year period, to compare the performance of the diagnostic tests used, to evaluate correlations with clinical data, and to genetically analyse the identified bacteria. During the study period, 1322 dogs tested by at least one of the rapid immunoenzymatic test, indirect immunofluorescent antibody test or end-point PCR assay for Anaplasmataceae detection were included. Dogs were tested if they had clinical signs or clinicopathological alteration or risk factors related to infection, and if they were potential blood-donor animals. Ninety-four of 1322 (7.1%) dogs tested positive for at least one pathogen: 53 (4.3%) for A. phagocytophilum, one (0.1%) for A. platys and 63 (4.6%) for E. canis. The number of dogs tested increased and the positivity rate progressively declined over the years. Comparison of tests showed a near-perfect agreement between serological tests and a poor agreement between PCR and indirect assays. A breed predisposition has been highlighted for A. phagocytophilum infection in hunting breed dogs and for E. canis infection in mixed breed dogs. Phylogeny confirmed potential zoonotic implications for A. phagocytophilum and showed no correlation of the identified bacteria with the geographical origin. Our study provides new insights into possible risk factors in dogs and evidenced discordant results between different tests, suggesting that a combination of serological and molecular assays is preferable for a correct diagnosis.

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.

Concomitant Infections With Canine Parvovirus Type 2 and Intracellular Tick-Borne Pathogens in Two Puppy Dogs

In this report the concomitant infection with canine parvovirus type 2 (CPV-2), Hepatozoon canis and Ehrlichia canis in two puppy dogs from Southern Italy is described. Dogs were referred to a veterinary university hospital for the acute onset of lethargy and gastrointestinal signs. A complete clinical and clinicopathological evaluation was carried out and the multiple infection was confirmed by microscopic detection of inclusion bodies in peripheral blood smear, rapid immunoenzymatic tests, indirect fluorescent antibody tests, and molecular assays. Sequence analysis revealed that the CPV-2 identified belonged to the 2c variant and had amino acid residues in the predicted VP2 protein typical of “Asian-like” strains widespread in Asia and occasionally reported in Romania, Nigeria and Italy, particularly in the region of Sicily. Numerous monocytes were infected by both H. canis gamonts and E. canis morulae, suggesting that this co-infection is not accidental and that E. canis preferably infects those cells parasitized by H. canis. The clinical presentation of these animals was severe but supportive cares associated with early etiological therapy allowed a good prognosis. Movement of puppies from geographic areas where vector-borne pathogens are endemic must be carefully evaluated and core vaccinations and ectoparasite prevention treatments must be rigorously adopted.