Haematological Alterations Associated with Selected Vector-Borne Infections and Exposure in Dogs from Pereira, Risaralda, Colombia

Molecular detection of Hepatozoon canis in dogs from Ibagué, Tolima

The genus Hepatozoon consists of apicomplexan protozoans that affect mammals, birds, amphibians, and reptiles. In dogs, the Hepatozoon species include H. canis and H. americanum, which are transmitted by the Rhipicephalus sanguineus tick and cause nonspecific signs, such as fever, weight loss, diarrhea, and blood disorders. These protozoans have a worldwide distribution in Europe, Asia, Africa, and North and South America, including Colombia. The aim of this study was to determine the prevalence and risk factors associated with H. canis in the urban and rural areas of Ibagué, Colombia. Blood samples were collected from 308 dogs (180 rural areas and 128 urban areas). Collected data included dog breed, sex, age, environmental factors, and the presence of ectoparasites. A fragment of the 18S rRNA gene was amplified by PCR for detection of the pathogen and confirmed by sequencing. Among the 308 samples, 14 were positive (14/308, 4.5%) for the presence of H. canis. The partial sequence of the 18S rRNA gene showed identity values >98% with H. canis, forming a cluster with sequences from Latin America. An epidemiological survey found two protective factors: most of the time at home (P=0.055) and overnight stay at home (P=0.03). This is the first molecular study of the prevalence and phylogeny analysis of H. canis in Ibagué, Colombia. The findings may help determine risk factors and enhance our understanding of the geographic distribution of H. canis in Colombia.

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.

Prevalence of zoonotic and non-zoonotic Rickettsia in horses: A systematic review and meta-analysis

In a broad sense, Rickettsiae are a group of microorganisms that can be transmitted mechanically or biologically to animals and humans. Rickettsioses are associated with hematic manifestations. Its prevalence in humans, dogs and other animals has been widely explored, but not in equine species. To determine the prevalence of Rickettsia infection in horses. A systematic review of the literature was carried out in five databases for the proportion of horses infected with Rickettsia, defined by molecular and immunological techniques. A meta-analysis was performed using a random-effects model to calculate the pooled prevalence and 95% confidence intervals (CI). The Cochran's Q test and the I² statistic were used to assess the between-study-heterogeneity. The pooled prevalence of Rickettsia in equines was 37.0% (95% CI: 26.0%-47.0%), with significant heterogeneity among studies (I² = 98.12%). In the subgroup analysis, the prevalence of Rickettsia in horses was found to be 24.0% (95%CI: 10.0%-41.0%) for IFI, 47.0% (95%CI: 30.0%-64.0%) for IFA, 14.0% (95%CI: 11.0%-17.0%) for IFAT and 39.0% (95%CI: 0.0%-95.0%) for PCR. There was a high prevalence of Rickettsia among horses, with some of the species being zoonotic, with their corresponding implications for humans, which increasingly are in close contact with equines, particularly horses and their ticks, posing a risk for spillover and transmission.