Demonstrating the presence of Ehrlichia canis DNA from different tissues of dogs with suspected subclinical ehrlichiosis

Abstract

Background Nowadays, Ehrlichia canis receives increasing attention because of its great morbidity and mortality in animals. Dogs in the subclinical and chronic phases can be asymptomatic, and serological tests show cross-reactivity and fail to differentiate between current and past infections. Moreover, there could be low parasitaemia, and E. canis might be found only in target organs, hence causing results to be negative by polymerase chain reaction (PCR) on blood samples. Methods We evaluated by PCR the prevalence of E. canis in blood, liver, spleen, lymph node and bone marrow samples of 59 recently euthanised dogs that had ticks but were clinically healthy. Results In total, 52.55% of the blood PCRs for E. canis were negative, yet 61.30% yielded positive results from tissue biopsies and were as follows: 63.15% from bone marrow; 52.63% from liver; 47.36% from spleen; and 15.78% from lymph node. In addition, 33% had infection in three tissues (spleen, liver and bone marrow). Conclusions Our results show the prevalence of E. canis from tissues of dogs that were negative by blood PCR. Ehrlichia canis DNA in tissue was 30% lower in dogs that tested negative in PCR of blood samples compared to those that were positive. However, it must be taken into account that some dogs with negative results were positive for E. canis in other tissues.

Looking for Dog Blood Donors in an Endemic Area for Vector-Borne Infections of Central Italy

“…It would be advisable to perform DNA detection tests on tissue samples, other than blood, from animals considered suspicious of having a subclinical Ehrlichia canis infection. It could be useful to take tissue biopsies from lymph nodes, blood marrow, and/or spleen as previously suggested and to be performed in chronically infected canines, irrespective of the serological status to E. canis , where PCR of DNA extracted from splenic aspirates is reported to be a reliable method for determining the carrier state of Canine Monocytic Ehrlichiosis [ 36 ]. Differently, the use of seropositive but PCR negative dogs may be acceptable for A. phagocytophilum in areas endemic for Ixodes spp., since identification of seronegative donors may be difficult [ 11 ].…”

First study on molecular detection of three major canine tick-borne pathogens in subclinically infected dogs in Chiang Mai, Thailand

“…This failure would be likely due to a low degree of parasitemia [ 14 ] and was unremarkable given the sample population likely in the subclinical phase of E. canis infection. It is also important to note that PCR tests using peripheral blood samples can fail to detect E. canis during the subclinical stage of infection due to the marginalization of the pathogen in certain organs, such as the spleen, liver, and bone marrow [ 46 ]. Therefore, our results may have underestimated the occurrence of E. canis in the sample population.…”

Prevalence and Clinical Characteristics of Ehrlichia Canis Infection in Dogs in Thua Thien Hue

“…These rates are much higher than those of Tran et al[3] when reporting 37/86 (43.02%) dogs with clinical signs of E. canis infection. In another study, Rodríguez et al[13] also found that 53/120 dogs showed signs of E. canis infection (44.1%). Our infected rate was also higher than that of Erdeger et al[5] reporting 91 dogs with a positive rate of 50.55%.…”

“…Nowadays, the disease receives increasing attention because of its worldwide occurrence, prevalence throughout the year, morbidity, and mortality. Furthermore, this disease attracted scientists from different parts of the globe, such as Brazil [1,12,13], Malaysia [11], and India [14], because of its complex dissemination.…”