Zoonotic Vector-Borne Diseases of Companion Animals

This study aimed to investigate the role of neutrophils in canine leishmaniosis by assessing neutrophil activation and its relationship with different states of L. infantum infection and antibody and IFN-γ production. Dogs were categorized into five groups: healthy-seronegative (n = 25), healthy-seropositive (n = 21), LeishVet-stage I (n = 25), Leishvet-stage II (n = 41), and LeishVet-stage III–IV (n = 16). Results of the nitroblue tetrazolium reduction test (NBT) showed significantly higher neutrophil activation in stage I (median:17.17, range: [7.33–31.50]%) compared to in healthy-seronegative (4.10 [1.20–18.00]%), healthy-seropositive (7.65 [3.98–21.74]%), stage II (6.50 [1.50–28.70]%), and stage III–IV (7.50 [3.00–16.75]%) groups (p < 0.0001). Healthy-seropositive dogs also displayed higher values than all groups except stage I. Stages II and III–IV did not show significant differences compared to healthy-seronegative. Regarding IFN-γ, stage I dogs had higher concentrations (median:127.90, range: [0–3998.00] pg/mL) than healthy-seronegative (0 [0–109.50] pg/mL) (p = 0.0002), stage II (9.00 [0–5086.00] pg/mL) (p = 0.045), and stage III–IV (3.50 [80.00–548.80] pg/mL) (p = 0.02) dogs. Stage II dogs showed increased IFN-γ compared to healthy-seronegative dogs (p = 0.015), while stage III–IV dogs had no significant differences compared to healthy-seronegative dogs (p = 0.12). Healthy-seropositive dogs had elevated IFN-γ concentrations compared to healthy-seronegative dogs (p = 0.001) and dogs in stage III–IV (p = 0.03). In conclusion, neutrophil activation was higher in dogs with mild disease and healthy-seropositive dogs, and a relationship between neutrophil activation and the production of IFN-γ was found. Full article

Ehrlichia chaffeensis is a tick-borne bacterium that causes human monocytotropic ehrlichiosis, an emerging life-threatening disease in humans transmitted by Amblyomma americanum. Although most studies have reported bacterial isolations and clinical cases in the United States, their occurrence is not restricted to North America. Some studies in the Southern Cone of South America have molecularly detected a close phylogenetic relative of E. chaffeensis in ticks and wild mammals. Even so, many gaps must be filled to confirm the presence of this agent in the region. To add new data on this issue, we report the first detection of specific anti-E. chaffeensis antibodies in dogs collected from all regions of Brazil. By means of IFA and ELISA with crude and specific antigens of E. chaffeensis, sera from 1134 dogs were analyzed. Serological analyses using ELISA showed nine (0.7%) seropositive dogs, with seven of them exhibiting IFA titers ranging from 160 to 5120. All regions of Brazil had at least one seropositive dog. Our results support the evidence for the occurrence of E. chaffeensis in South America. As dogs have a close relationship with humans, they can be used as an environmental sentinel for these infections because they can act as a bridge to human parasitism or infection with ehrlichial agents. Full article

Trypanosoma cruzi infection causes inflammation and fibrosis, resulting in cardiac damage in dogs. The objectives of this study were to describe cardiac magnetic resonance imaging (CMR) in naturally infected dogs with chronic Chagas disease and the frequency of abnormalities for CMR and cardiac diagnostic tests. Ten asymptomatic, client-owned dogs seropositive for T. cruzi were prospectively enrolled in an observational study evaluating echocardiography, ECG (standard and ambulatory), cardiac troponin I (cTnI), and CMR. Standard ECG measurements (3/10) and cTnI concentration (1/10) outside the reference range were uncommon. Ambulatory ECG abnormalities were documented more frequently (6/10 dogs) than with standard ECG and included ventricular arrhythmias (4), supraventricular premature beats (3), second-degree atrioventricular block (2), and sinus arrest (1). Echocardiographic abnormalities were documented in 6/10 dogs including mildly increased left ventricular internal dimension in diastole (1) and decreased right ventricular (RV) systolic function based on reductions in tricuspid annular plane systolic excursion (3) and RV S’ (4). Abnormalities were detected with CMR in 7/10 dogs including delayed myocardial enhancement in 5 of which 2 also had increased extracellular volume, abnormal wall motion in 5, and loss of apical compact myocardium in 1. In conclusion, CMR abnormalities were common, and the results of this study suggest CMR can provide useful information in dogs with T. cruzi infection and may support naturally infected dogs for future clinical investigation as an animal model for Chagas disease. Full article

Brazilian spotted fever (BSF) is the most important tick-borne diseases affecting humans in Brazil. Cases of BSF have recently been reported in the Goiás state, midwestern Brazil. All cases have been confirmed by reference laboratories by seroconversion to Rickettsia rickettsii antigens. Because serological cross-reactions among different rickettsial species that belong to the spotted fever group (SFG) are common, the agent responsible for BSF cases in Goiás remains unknown. From March 2020 to April 2022, ticks and plasma were collected from dogs, horses and capybaras (Hydrochoerus hydrochaeris), and from the vegetation in an area where BSF cases have been reported and two areas under epidemiological surveillance in Goiás. Horses were infested by Amblyomma sculptum, Dermacentor nitens and Rhipicephalus microplus; dogs by Rhipicephalus sanguineus sensu lato (s.l.), Amblyomma ovale and A. sculptum, and capybaras by A. sculptum and Amblyomma dubitatum. Adults of A. sculptum, A. dubitatum, Amblyomma rotundatum and immature stages of A. sculptum and A. dubitatum, and Amblyomma spp. were collected from the vegetation. DNA of Rickettsia that did not belong to the SFG was detected in A. dubitatum, which was identified by DNA sequencing as Rickettsia bellii. Seroreactivity to SFG and Rickettsia bellii antigens was detected in 25.4% (42/165) of dogs, 22.7% (10/44) of horses and 41.2% (7/17) of capybaras, with higher titers for R. bellii in dogs and capybaras. The seropositivity of animals to SFG Rickettsia spp. antigens demonstrates the circulation of SFG rickettsiae in the region. Further research is needed to fully determine the agent responsible for rickettsiosis cases in this area. Full article

Anaplasma phagocytophilum is an obligate intracellular bacterium that causes granulocytic anaplasmosis in domestic animals, wildlife, and humans and is primarily transmitted by ticks of the Ixodes persulcatus complex. This retrospective study aims to determine the percentages of dogs that tested positive for A. phagocytophilum in Germany. It included the results of direct (polymerase chain reaction [PCR]) and indirect (immunofluorescence antibody test [IFAT], antibody-enzyme-linked immunosorbent assay [ELISA]) detection methods performed in the laboratory LABOKLIN on canine samples provided by German veterinarians from 2008 to 2020. Out of a total of 27,368 dogs tested by PCR, 1332 (4.9%) tested positive, while 24,720 (27.4%) of the 90,376 dogs tested by IFAT/ELISA had positive serology. High rates of positive PCR results were observed in months with known peaks in vector activity, showing that the dynamics of A. phagocytophilum infections in dogs in Germany are consistent with vector activity. In dogs with a positive PCR result, peaks in serology could be observed four weeks after initial testing. Male and senior dogs had higher rates of positive serology. A possible impact of environmental factors such as changes in climate should be investigated further. Overall, the upward trend in positive test results over the years indicates that canine granulocytic anaplasmosis will continue to become increasingly important for veterinary medicine. Full article

Linguatula serrata, Frohlich, 1789, is a cosmopolitan zoonotic worm-like parasite of carnivores and other vertebrates including herbivores and omnivores. The adult form of the parasite typically inhabits the upper respiratory system, nares, and frontal sinuses of dogs, wolves, and cats. Infective eggs may be spread by sneezing, nasal secretions, and stool. The immature stages of the parasite are localized in the visceral organs of intermediated hosts, usually ruminants or rodents, and they are orally transmitted to predators during the ingestion of infested viscera. This paper reports the morphological identification and the molecular characterization of L. serrata specimen collected from a gray wolf in the Apulia region (southern Italy) and it also provides epidemiological information on this rarely reported zoonosis. Full article