Epidemiology and genetic diversity of Anaplasma marginale in Zamora-Chinchipe, Ecuador

Land system governance shapes tick-related public and animal health risks

Land cover and land use have established effects on hazard and exposure to vector-borne diseases. While our understanding of the proximate and distant causes and consequences of land use decisions has evolved, the focus on the proximate effects of landscape on disease ecology remains dominant. We argue that land use governance, viewed through a land system lens, affects tick-borne disease risk. Governance affects land use trajectories and potentially shapes landscapes favourable to ticks or increases contact with ticks by structuring human-land interactions. We illustrate the role of land use legacies, trade-offs in land-use decisions, and social inequities in access to land resources, information and decision-making, with three cases: Kyasanur Forest disease in India, Lyme disease in the Outer Hebrides (Scotland), and tick acaricide resistance in cattle in Ecuador. Land use governance is key to managing the risk of tick-borne diseases, by affecting the hazard and exposure. We propose that land use governance should consider unintended consequences on infectious disease risk.

Molecular surveillance and genetic diversity of Anaplasma spp. in cattle (Bos taurus) and goat (Capra aegagrus hircus) from Hainan island/province, China

Anaplasmosis is a highly prevalent tick-borne intracellular bacterial disease that affects various host species globally, particularly ruminants in tropical and subtropical regions. However, information regarding the distribution and epidemiology of anaplasmosis in small and large ruminants on Hainan Isalnd is limited. To address this knowledge gap, the present study aimed to assess the occurrence of Anaplasma spp. infections in goats (N = 731) and cattle (N = 176) blood samples using nested PCR and conventional PCR based assays. The results revealed an overall prevalence of 30.1% in goats and 14.8% in cattle. The infection rates of A. bovis, A. phagocytophilum, A. ovis and A. capra in goat samples were 22.7%, 13.8%, 2.0% and 3.4%, respectively, while the infection rates of A. bovis, A. phagocytophilum and A. marginale in cattle samples were 11.4%, 6.3% and 5.7%, respectively. A. bovis exhibited the highest prevalence among the Anaplasma spp. in both goat and cattle samples. In addition, the most frequent co-infection was the one with A. phagocytophilum and A. bovis. It was found that the age, sex and feeding habits of cattle and goats were considered to be important risk factors. Evaluation of the risk factor relating to the rearing system showed that the infection rate for the free-range goats and cattle was significantly higher when compared with stall-feeding system.This study represents one of the largest investigations on the distribution, prevalence, and risk factors associated with Anaplasma infection in ruminants on Hainan Island, highlighting a higher circulation of the infection in the region than previously anticipated. Further reasesrch is necessary to investigate tick vectors, reservoir animals, and the zoonotic potential of the Anaplasma spp. in this endemic region of Hainan Island.

Molecular identification of Trypanosoma theileri (Laveran, 1902) in cattle from two slaughterhouses in Ecuador and its relation with other haemotropic agents

Trypanosoma theileri is a worldwide distributed haemoparasite that has been reported throughout the American continent in various species, including bovines, buffaloes and bats. In bovines, high incidence of T. theileri can be harmful when associated with other infections or under stress situations. There is little information on this hemoflagellate in Ecuador, which prompted the study and molecular identification of the trypanosomes collected in two slaughtering centers. Between February and April 2021, a total of 218 samples of bovine blood were collected in abattoirs located in the Andean region of Quito (n = 83) and in the coastal region, in Santo Domingo (n = 135). Quito public Slaughterhouse is the biggest in Ecuador, and for that, they receive animals from all country; on the other hand, Santo Domingo's Slaughterhouse is a small one where mainly females from the region are sacrificed and some males. The samples were evaluated using two molecular tests, the PCR cathepsin L-like (CatL) specific for T. theileri and for the positive samples, a Nested PCR that targets the ITS of the 18S gene. The corresponding PCR products were sequenced, analyzed by BLAST/NCBI and the sequences were used to build a concatenated phylogenetic tree, using the MEGA XI software. Overall, 34 out of the 218 samples, (15.6%) were positive to T. theileri by PCR CatL, resulting from 20/83 (24.1%) positives from the Quito abattoir and 14/135 (10.4%) from the Santo Domingo slaughterhouse. These prevalence rates were found to be significantly different (p = 0.006). According to the phylogenetic tree based on the CatL and ITS concatenated sequences (n = 13), the two novel Equatorial T. theileri isolates, ThI (n = 7) and ThII (n = 6) are closely related and associated to the IC, IB and IIB genotypes, present in Brazil, Venezuela and Colombia. Thirty-one out of the thirty-four T. theileri-positive bovines were co-infected with other haemotropic pathogens, Anaplasma marginale Babesia spp and T. vivax. This coinfection could be responsible for additional pathologies and harmful effects on the affected cattle. This study presents the molecular identification and genotypification of T. theileri isolated from cattle in Ecuador through the analysis of CAtL and ITS sequences, and the high frequency of coinfection of this hemoflagellate with other blood haemotropic organisms.

Characterization of strains of Anaplasma marginale from clinical cases in bovine using major surface protein 1a in Uruguay

The major surface protein 1a (MSP1a) gene has been used to characterize Anaplasma marginale genetic diversity. This pathogen causes significant productivity and economic losses to the cattle industry. The objective of the present study was to report the first characterization of A. marginale genetic diversity in Uruguay based on MSP1a genotypes and their putative relationship with Rhipicephalus microplus. This cross-sectional study was conducted between 2016 and 2020. The study included whole blood samples from clinical cases of bovine anaplasmosis obtained from 30 outbreaks located in six Uruguay territorial departments. Diagnosis was performed using Giemsa-stained smears and confirmed by nested Polymerase Chance Reaction (nPCR) targeting the A. marginale major surface protein 5 gene. The genetic diversity of A. marginale strains was characterized by analyzing the microsatellite and tandem repeats of MSP1a. Based on the microsatellite structure, four genotypes were identified. Genotype E was the most prevalent. Analysis of MSP1a tandem repeats showed 28 different strains from the combination of 31 repeats, with τ-10-15 and α-β-β-β-Γ being the most common. Repeats Γ, β, α, and γ were associated with the absence of R. microplus with statistical significance (p < 0.05). Molecular observations showed that 46.7% of the strains identified in our samples lacked the ability to bind to tick cells; therefore, they were probably transmitted by other vectors. Strain genetic diversity provides valuable information for understanding the epidemiological behavior of A. marginale and could contribute to the development of effective vaccines for the control of this disease.

Sensitivity of Anaplasma marginale genotypes to oxytetracycline assessed by analyzing the msp1α gene in experimentally infected cattle

The aim of this study was to evaluate the influence of the long-acting oxytetracycline (OTC) treatment on A. marginale genotypes of the isolate S1P, by analyzing the msp1α genotype based on a microsatellite (ms) and tandem repeat sequences (TRS) located at the 5´ end of the gene. DNA samples were obtained from a longitudinal study of chemosterilization; 10 2-year-old steers were experimentally infected with blood from a splenectomized calf inoculated with the A. marginale isolate S1P. All the steers had received a first dose of 20 mg kg^-1 OTC to treat acute disease, and once recovered all steers received a sterilizing treatment based on three doses of 20 mg kg^-1 OTC 7 days apart. Blood from two steers not sterilized by the treatment was inoculated into two splenectomized calves (receptors) 104 days after treatment. DNA samples (S) used for msp1α amplification were obtained from i) the donor calf (S0), ii) 10 steers during acute disease (S1), after the first antibiotic treatment (S2), and after the chemosterilization procedure (S3 and S4), and iii) two receptor calves (S5). Thirty clones from the donor calf and at least 5 clones from the other DNA samples were analyzed. The genotype E/αββββГ msp1α identified in the donor calf and steers, before OTC treatment, was not detected either in steers that continued infected after the sterilizing treatment or in the receptor calves, in which only genotype C/EϕFF msp1α was observed. These results highlight the existence of A. marginale genotypes with different sensitivity to OTC and the importance of other variables to successfully sterilize the carriers.