Evaluation of the euthanasia of seropositive dogs for canine visceral leishmaniasis as the only method of controling the disease in the enzootic area in the Midwestern Minas Gerais

ABSTRACT: Human Visceral Leishmaniasis (VL) is expanding, and it is distributed in the five geographic regions of Brazil, with the Northeast being the region that presents the most significant number of registered cases. The main urban reservoir of the etiological agent of VL is the domestic dog, and it is known that canine cases precede human cases. One of the control actions of VL, recommended by the Ministry of Health, is performing the euthanasia of seropositive dogs. In 2013, in the municipality of Iguatama/MG, the first canine serological survey was carried out in the city, with a prevalence of 8.3% of seropositive dogs for Leishmania infantum. Of the seropositive animals for Canine Visceral Leishmaniasis (CVL) in this survey, 84% were euthanized, and 16% died within two years after diagnosis. No other control measures for CVL were taken in the municipality. The objectives of the present study were to determine the current prevalence of seropositive dogs for CVL in the municipality of Iguatama and to observe the impact of euthanasia of seropositive dogs to VL as the only control measure performed in this municipality, which is considered an enzootic area of the disease. For this, a new canine epidemiological survey was carried out in the municipality of Iguatama, following the guidelines of the Manual of Surveillance and Control of Visceral Leishmaniasis. Blood samples were collected from 270 dogs and tested by DPP® immunochromatographic test and by Enzyme-Linked Immunosorbent Assay (ELISA). The animals that presented inconclusive results had new blood samples collected and analyzed. The only animal that showed a positive result in DPP® and undetermined in the ELISA, in the first evaluation, became seropositive four months later, so this study reinforces the recommendation of the Ministry of Health to reassess dogs that present inconclusive results for CVL. From a total of 270 samples, 21 (7.8%) were reagents in both tests. Thus, the prevalence of seropositive dogs for CVL, in 2017, in the urban area of the municipality of Iguatama was 7.8%. The Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) molecular technique confirmed infection by L. infantum in the ten dogs sampled with CVL-positive serology. The comparison between the current prevalence (after euthanasia) with that found in 2013 (8.3%), there was no significant difference (p=0.764). The prevalence of CVL in the urban area of the municipality of Iguatama is still high, making it possible to presume that the euthanasia of seropositive dogs for CVL, and the absence of monitoring or other interventions measures, did not contribute to decrease the transmission of the parasite and was not sufficient for the control of CVL in the municipality of Iguatama, an area considered as non-endemic to CVL until 2013.

Effect of Coinfection by fasciola hepatica and mycobacterium bovis on Bovine Tuberculosis Immunodiagnosis in an Enzootic Area Hidalgo State, Mexico.

Parasitic infection by the Fasciola hepatica (F. hepatica) promotes susceptibility towards other infections, such as Mycobacterium bovis. As consequence, could affect diagnostic tests for this disease. Hence, the objective of this study was to assess the impact of F. hepatica coinfection on the most commonly used immunodiagnostic bovine tuberculosis (bTB) tests in field conditions in an enzootic area for both diseases. Thus, from a dairy herd located in Hidalgo State, México, displaying a 59.2% and 28% prevalence of fascioliasis and bTB, respectively. Sixty-one cows were analyzed based on their response towards bTB immunodiagnostic tests, such as Single Intradermal Comparative Tuberculin Test (SICTT), gamma-interferon test (BOVIGAM) and enzyme-linked immunosorbent assay (ELISA), along with the assessment of the F. hepatica parasite load and serodiagnosis by ELISA. Three study groups were formed according to test results. Group 1: coinfected (n=22). Group 2: non-parasitized cows, and positive for bTB tests (n=13) and Group 3: parasitized cows without tuberculosis (n=26). In addition, a group of cows kept in fascioliasis - and tuberculosis-free zones were included (Group 4, n=10). A non-parametric Kruskal-Wallis test and a Dunn test were applied to analyze the results. In Group 1, significant differences were observed regarding IFN-γ production, but not for antibody levels to M. bovis or reactivity towards bovine PPD in relation Group 2. While, Groups 1 and 3 did not display difference in antibody levels against F. hepatica. Differences were observed regarding tuberculosis and Fasciola diagnostic tests when both coinfected and infected groups were compared to controls. It is concluded that F. hepatica coinfection in tuberculous animals studied, depressed the production of IFN-γ towards bovine PPD under in vitro conditions, but its reactivity to the SICTT not show to be altered.

Fleas as Vectors of Especially Dangerous Infections in Jermuk Region, 2010-2016

ObjectiveThe goal was to determine the impact of flea number variation on the epizootic situation in the Jermuk region.IntroductionThe Jermuk region of the Zangezur mezofocus is part of the transcaucasian highland focus of plague. This enzootic area is polyvectorial. The mezofocus has rich fauna with approximately eight species of fleas: Callopsylla caspia, Ctenophthalmus wladimiri, Frontopsylla elata, Amphipsylla rossica, Leptopsylla taschenbergi, Nosopsyllus consimilis, Palaeopsylla vartanovi, and Doratopsylla dampfi. Ct. wladimiri is the most abundant. However, special attention should be paid to C. caspia and N. consimilis as they are the only vectors specific for Yersinia pestis. In these fleas, the bacteria form a plug that blocks digestion and induces starvation. Afflicted fleas bite frenziedly in an effort to feed and the pressure that results releases bacteria from the plug, infecting a new host. Fleas infected with plague during an epizootic are a serious threat to humans, especially when in contact with synanthropic rodents. A survey was conducted to catalog fleas in the foci.MethodsFrom 2010-2016 different species of fleas were collected in Jermuk region of Vayots Dzor by combing the hair of captured rodents and processing their nests with heat and light. Flea species, and their egg-laying status, were identified by microscopic examination.ResultsFrom 2010-2015 the density of C. caspia averaged 23 per hectare. Fleas that were laying eggs were quantified via microscopy. In 2016 a drastic increase in C. caspia density was recorded; flea numbers averaged 225 per hectare. Half of these were actively reproducing (Table 1). These changes in flea numbers occurred with a stable rodent population of 60 per hectare.ConclusionsBecause of the drastic increase in flea density of 2016 compared to the period of 2010-2015, it is likely that diseases that depend on fleas to spread will increase in the near future in Jermuk. So, it is necessary to monitor the epizootic situation of Jermuk, as it is a popular resort in Armenia.

Human ocular dirofilariosis in Slovakia, a case report

A case of the human ocular dirofilariosis in 72-year-old man from southern Slovakia is documented. Two days before visiting a doctor he noticed a live worm in his right eye. The eye was inflamed and itching. The worm of 100 mm in length was isolated from the subconjunctival space. On the basis of morphological appearance, histological examination and PCR-based detection, it was identified as Dirofilaria repens. The patient was probably infected in the southern Slovakia, which is an enzootic area of dirofilariosis of dogs.