Canine ehrlichiosis: prevalence and epidemiology in northeast Brazil

Molecular Confirmation, Epidemiology, and Pathophysiology of Ehrlichia canis Prevalence in Eastern India

The present study aimed to investigate pathological epidemiology and molecular confirmation of Ehrlichia canis among pet dogs in Bhubaneswar, Odisha, a state in eastern India. A total of 178 dogs were screened for Ehrlichiosis based on history, clinical signs, blood, and buffy coat smear examination, resulting in only 56 dogs (31.46%) screening positive. The epidemiological study recorded a non-significant (p ≥ 0.05) increase in incidences among male dogs (68%), German Shepherds (25%), dogs more than 20 kg body weight (75%), in the summer months (55%), and dogs housed in pukka houses with exposure to the outside (59%). The majority of the infected dogs had a history of tick infestation (79%) at some point in their lives. Clinical signs showed non-typical manifestations like fever, lethargy, diarrhoea, epistaxis, hind limb edema, and corneal opacity. Haematological studies revealed anaemia and thrombocytopenia along with neutrophilia with relative lymphopenia and monocytosis. A decreasing trend was observed in the levels of total protein and albumin, with an increase in the levels of globulin, alanine aminotransferase, alanine aminotransferase, aspartate aminotransferase, blood urea nitrogen, and creatinine. The ultrasonography studies revealed hepatosplenomegaly along with hyper-echogenicity in various organs. Proteinuria and haematuria were consistent, along with the presence of bile salts in the urine of affected dogs. Molecular confirmation from n-type PCR data using Ehrlichia-specific primers targeting the p28 gene (843 bp) was done, and the identified gene sequences submitted to NCBI databases have accession numbers OQ383671-OQ383674 and OP886674-OP886677. Ticks collected from dogs were identified morphologically through microscopy and scanning electron microscopy as Rhipicephalus sanguineus.

Effects of Doxycycline Treatment on Hematological Parameters, Viscosity, and Cytokines in Canine Monocytic Ehrlichiosis

This study aimed to analyze the hematological parameters, blood viscosity, and cytokines of dogs infected by Ehrlichia canis untreated and treated with doxycycline. Initially, 47 dogs were examined, and 36 were suspected to have canine monocytic ehrlichiosis, which was confirmed through molecular polymerase chain reaction tests. This study consisted of 25 dogs, with 11 being healthy and 14 testing positive for E. canis. The dogs were divided into experimental groups based on their test results, including a control group of healthy dogs (N = 11), a group of infected dogs without treatment (N = 7), and a group of infected dogs treated with doxycycline (N = 7) at a 10 mg/kg dose every 12 h for 28 days. Blood samples were taken to determine hematological parameters, viscosity, and cytokine levels. It was observed that, regardless of doxycycline treatment, there was a reduction in total leukocytes and lymphocytes in infected dogs with Ehrlichia canis. The eosinophils and platelets decreased in dogs with Ehrlichia canis infections without treatment. Monocytes, eosinophils, and platelets increased when the dogs were treated with doxycycline. Regardless of treatment, infected dogs' blood viscosity was lower than uninfected dogs. Infected dogs showed lower TNF-α and increased IL-1β. There was a correlation between the blood viscosity with the cytokines IL-10 and IL-12 in the infected dogs. The eosinophil count correlated with TNF-α in the group of infected and untreated dogs. In conclusion, treating dogs with monocytic ehrlichiosis using doxycycline can increase platelet and eosinophil levels but may also increase IL-1β and monocyte levels, exacerbating inflammation. Therefore, evaluating viscosity and cytokine levels is important when treating dogs with this condition.

Molecular Detection and Characterization of Ehrlichia canis Isolates from Three Geographic Regions in Mexico: A Retrospective Study

Canine monocytic ehrlichiosis (CME) is the most common tick-borne disease affecting domestic dogs and other wild canids. It has a worldwide distribution and is associated with the presence of the brown dog tick. Few studies have been conducted in Mexico to identify and characterize Ehrlichia canis genetic variability. In the present study, 111 dogs of different sex, breed, and age from three geographic regions in Mexico were included. All of them had a previous history of tick infestation and/or the presence of one or more clinical signs compatible with CME. All dogs were tested by a commercial ELISA and nested PCR assay for the detection of E. canis. In addition, we analyzed the E. canis genetic diversity from the 16S rRNA gene sequences obtained in this study, along with 15 additional sequences described for E. canis in Mexico and obtained from GeneBank. Serological detection by commercial ELISA results showed overall infection rates of 85.58% (95/111), including 73.1% (30/41) in samples from Guerrero state; 75% (15/20) in Morelos; and 100% (50/50) in Chihuahua. On the other hand, molecular detection (nPCR assay) showed 31.5% (35/111) overall infection rate, with 41.4% (17/41) in Guerrero state; 55% (11/20) in Morelos; and 14% (7/50) in Chihuahua. We observed a high 16S rRNA gene sequence conservancy in most of the E. canis isolates in the three geographical areas from Mexico, including those analyzed in this research, suggesting a common geographic origin among isolates.

Socioeconomic Status of Guardians as a Risk Factor for Canine Visceral Leishmaniasis: A Cohort Study in an Endemic Area of the Federal District, Brazil

Current control measures of canine visceral leishmaniasis (CVL), a chronic and fatal zoonosis with potential transmission to humans, are not efficient enough to reduce its spread. The search for improved control measures should include studies of risk factors for infection and illness. This study aimed to identify the risk factors for CVL in an endemic locality of the Federal District, Brazil, from June 2016 to December 2018. Biologic samples and data on dog characteristics, owner household characteristics, and dog care were collected. A combination of serological and molecular tests was used to identify infected animals. The 248 dogs screened for inclusion were predominantly asymptomatic/oligosymptomatic. The baseline prevalence of infection was 27.5%. One hundred six of 162 susceptible dogs were monitored for an average period of 10.7 months. The estimated CVL incidence was 1.91 cases/100 dog-months. The multivariate analysis using a proportional Cox model included the potential risk factors, with P ≤ 0.25 in the univariate analyses. Greater purchasing power (hazard ratio [HR], 1.04; 95% CI, 1.01-1.06; P = 0.03) and paved yard (HR, 0.19; 95% CI, 0.13-1.01; P = 0.05) remained in the final model as risk and protection factors, respectively. The use of repellent collars in dogs was associated moderately (P = 0.08) with protection against CVL. Our findings reflect the challenge of identifying strong interventions for reducing CVL incidence. Increased owner wealth had a counterintuitive effect on CVL, making the intervention scenario more complex for a zoonosis traditionally associated with poverty.

Retrospective analysis of canine monocytic ehrlichiosis in Thailand with emphasis on hematological and ultrasonographic changes

Background and Aim: Canine monocytic ehrlichiosis (CME) is a tropical endemic tick-borne disease that causes fatality or chronic infection involving many organs in dogs. This study aimed to examine the prevalence, risk factors, and hematological and ultrasonographic changes in the liver, gallbladder, kidneys, and spleen following CME infection. Materials and Methods: This retrospective study used 30,269 samples collected from dogs at the hematology section of the pathology unit of a university veterinary hospital and 35 samples collected from dogs at the diagnostic imaging unit. CME was determined using the buffy coat smear method. Data were analyzed using descriptive statistics and odds ratios. Results: CCl4 The data revealed that the average yearly prevalence of CME was 1.32%. Risk factors contributing to CME infection were a tick on the body during physical examination, lack of ectoparasite control, and outdoor living. All 148 dogs with CME infection had low platelet counts. The percentages of CME-infected dogs with elevated serum alanine aminotransferase, alkaline phosphatase, and both enzymes above the normal range were 33.6%, 65.9%, and 29.8%, respectively. The rates for elevated serum levels of blood urea nitrogen, creatinine, and both compounds were 33.1%, 19.1%, and 17.3%, respectively. The most common ultrasonographic changes were liver abnormalities (hyperechogenicity or hypoechogenicity, hepatomegaly, and hypoechoic nodules), hyperechogenicity of the kidneys, and an enlarged spleen. These ultrasonographic changes were consistent with the hematology results, which showed a greater elevation of serum liver enzyme levels than renal enzymes. Conclusion: Ultrasonographic changes during CME infection and after treatment with doxycycline can help to monitor and identify persistent pathological changes in the target organs resulting from immune response to CME.

Molecular detection and risk factors for Anaplasma platys infection in dogs from Egypt

Background

Anaplasma platys is a tick-borne bacterium which infects blood platelets of dogs, causing canine cyclic thrombocytopenia. The disease is distributed worldwide, particularly in the tropics and subtropics, but information on the epidemiology of A. platys infection in dogs is fragmentary in many countries, including Egypt. In this study, we investigated the prevalence and risk factors associated with A. platys infection in dogs from Egypt.

Methods

A conventional PCR targeting a fragment of the 16S rRNA gene of A. platys was used to screen 500 dogs from five North Egyptian governorates. DNA sequencing and phylogenetic analysis were performed for one of the positive samples.

Results

The overall prevalence of A. platys in the studied dogs was 6.4%. Females of the German shepherd breed without veterinary care had higher odds for A. platys positivity. High tick infestation and lack of anti-tick treatment were also identified as risk factors for A. platys infection. Phylogenetic analysis revealed that the sequence obtained herein was closely related to sequences from Egypt, South Africa and Uruguay.

Conclusions

This is the first large-scale epidemiological study of A. platys in Egypt, where female German shepherd dogs without veterinary care, as well as dogs with high tick infestation and without anti-tick treatment are at a higher risk of infection.

Graphical abstract

Ehrlichia canis morulae in peripheral blood lymphocytes of two naturally-infected puppies in Israel

Ehrlichia canis is the major causative agent of canine monocytic ehrlichiosis (CME). Its morulae might be detected during the acute disease phase, usually within peripheral blood monocytes, but were uncommonly described within peripheral blood lymphocytes. This report describes two unrelated puppies, naturally infected with E. canis. In both, examination of stained peripheral blood smears revealed one to several cytoplasmic inclusions, characteristic of typical E. canis morulae, exclusively within lymphocytes. Ehrlichia canis infection was confirmed in both cases by blood sample real-time PCR. Both dogs were young and had comorbidities. One dog, based on whole blood PCR, was co-infected with Anaplasma platys and Babesia vogeli. The other had no other concurrent tick-borne infection based on PCR, but had bacterial cholangiohepatitis. These comorbidities, and the dogs' young age possibly contributed to the uncommon presence of E. canis morulae within peripheral blood lymphocytes rather than their typical presence in monocytes.

High Performance of ELISA test using recombinant rLiNTPDase2 from Leishmania infantum: a Phase II diagnosis of Canine Visceral Leishmaniasis

Canine visceral leishmaniasis (CVL) has been the theme of several studies given the importance of dog as natural reservoir of the pathogen Leishmania infantum in endemic regions and its role on dissemination of CVL and human visceral Lesihmaniasis (VL). The current immunodiagnosis of CVL has limitations concerning accuracy, specificity and sensitivity. Therefore, improvements are required. rLiNTPDase2 has been previously highlighted as a new recombinant antigen from L. infantum to the CVL diagnosis by ELISA assay (rLiNTPDase2-ELISA). In this study, we aimed to evaluate rLiNTPDase2-ELISA in a Phase II study with 651 dog sera samples, also comparing it with methodologies previously established and used in epidemiology surveillance in Brazil, an endemic country of CVL and VL. The rLiNTPDase2-ELISA using standard control sera showed high capability to distinguish between positive and negative sera, sensitivity of 92.6% and specificity of 88.5%. The test was reproductive and the kappa statistics judgement "substantial agreement". rLiNTPDase2-ELISA does not show cross-reactivity with ehrlichiosis-reagent sera. However, we verified 15.3% of cross-reactivity with Chagas disease-reagent sera. The performance of rLiNTPDase2-ELISA was evaluated using sera samples from vaccinated dogs (Leish-Tec®). The results showed high agreement with parasitological and PCR results (sensitivity of 100.0% and specificity of 91.7%). Furthermore, we compared the performance of rLiNTPDase2-ELISA in CVL-reagent sera samples from endemic areas, which were previously diagnosed using other tests for CVL: immunofluorescent (IFI-LVC-Bio-Manguinhos), IFI-LVC-Bio-Manguinhos coupled to ELISA (EIE-LVC-Bio-Manguinhos) and the Rapid Dual Path Platform® (TR-DPP®-Bio-Manguinhos) coupled to EIE-LVC-Bio-Manguinhos. rLiNTPDase2-ELISA showed high level of concordance with IFI-LVC-Bio-Manguinhos (88.6%) and with IFI-LVC-Bio-Manguinhos coupled to EIE-LVC-Bio-Manguinhos (82.9%) but not with TR-DPP® -Bio-Manguinhos coupled to EIE-LVC-Bio-Manguinhos (33.3%), which casts doubts on the effectiveness of this latest test. In addition, the rLiNTPDase2 antigen adsorbed in 96-well plate was stable enough to be used at least for three months. Taken together, our data confirmed, by Phase II study using hundreds samples, the good potential of rLiNTPDase2-ELISA to be used in the field as a new diagnostic assay for CVL.

Serological and molecular diagnosis of Ehrlichia canis and associated risk factors in dogs domiciled in western Cuba

Ehrlichia canis is a rickettsia transmitted by the tick, Rhipicephalus sanguineus, and is the causative agent of canine monocytic ehrlichiosis (CME). In Cuba, the first diagnosis of CME was made in 2001, but few studies have since investigated this disease locally. The objective of this study was to estimate the prevalence of E. canis in dogs domiciled in four municipalities within the western region of Cuba and determine the associated risk factors. Blood was drawn from 378 selected dogs living in four municipalities in two provinces of western Cuba. From the total number of samples, 206 plasma samples were selected to perform an enzyme-linked immunosorbent assay (ELISA) to detect antibodies against E. canis. Using the original 378 samples of extracted DNA, a nested polymerase chain reaction (nPCR) was performed to amplify a specific fragment of the 16S rRNA gene of E. canis. Analysis of the 206 plasma samples revealed a total of 162 animals that were seropositive for E. canis (78.64%) with a density index between 109.5 and 970.7. In contrast, 179 samples were positive based on the nPCR assay (47.35%). As well, there was a high concordance (kappa = 0.7), calculated through the Kappa index, between the animals found to be positive based on nPCR and those determined based on ELISA. The analysis of risk factors showed that residing in the municipality of Boyeros in addition to having a history of infestation by ticks increases the probability of having a positive result based on nPCR.

Molecular epidemiology of Anaplasma platys, Ehrlichia canis and Babesia vogeli in stray dogs in Paraná, Brazil

ABSTRACT: Hemoparasitic infections are tick-borne diseases, which affect animals and humans. Considering the importance of canine hemoparasitic infections in veterinary clinics, this study aimed to determine the occurrence of Anaplasma platys, Ehrlichia canis and Babesia vogeli in blood samples from 182 dogs not domiciled in the city of Pato Branco, southwestern region of Paraná State, Brazil, using polymerase chain reaction (PCR). The prevalence of A. platys and B. vogeli was 32.9% and 10.9% respectively, and A. platys infection prevailed (p<0.001). The number of dogs positive for A. platys was larger in Winter (p<0.05). All blood samples were negative for E. canis. In the dogs, infestation by Amblyomma cajennense predominated over that by Rhipicephalus sanguineus (p<0.001); but there was no significant association between PCR and the variables presence of ticks, sex and age. Dogs infected by A. platys and B. vogeli showed thrombocytopenia, lymphopenia and leukocytosis; but there was no correlation between such hematological changes and infection by hemoparasites. This appears to be the first molecular study that demonstrates the existence of A. platys and B. vogeli in dogs from the southwestern region of Paraná.