农林科学最新文献

Intracytoplasmic inclusions in atrial cardiomyocytes of guinea pigs were incidentally identified on routine postmortem evaluation. This study was conducted to assess their location, incidence, morphology, staining properties, ultrastructural appearance, epidemiological characteristics, and pathologic significance. Retrospective cases from 2014 to 2022 with right and/or left atria sampled for histologic examination were selected, and hearts of guinea pigs necropsied in 2023 were systematically formalin-fixed and included. Inclusions were identified in 27 of 28 animals (96%). They were significantly more numerous in the right atrium compared with the left atrium (P < .001, Wilcoxon signed-rank test) and preferentially located as clusters in the subendocardial region. None of these inclusions were detected in the ventricular myocardium. These inclusions were intracytoplasmic, ovoid to linear, frequently fragmented, slightly basophilic to amphophilic in hemalum, eosin, and saffron-stained sections and measured from 1 to 130 µm in length. They stained positively with periodic acid-Schiff, Gomori-Grocott's methenamine silver, and Alcian blue pH 2.5; negatively or unstained with Alcian blue pH 1, toluidine blue, von Kossa, Congo red, and Masson's trichrome; and were amylase resistant. Transmission electronic microscopy revealed slightly electron-dense, non-membrane-bound aggregates of filaments interspersed with granular material compatible with polyglucosan bodies. Animals under 1-year-old had significantly fewer inclusions than older animals (P = .002, Mann-Whitney U test). Inclusion density in the right atrium was not associated with sex, body weight, local heart lesions, or cardiac or systemic disease. Those features are similar to a human condition named basophilic degeneration, reported here for the first time in guinea pigs.

In the summer of 2023 in southern Brazil, there was a fatal outbreak of acute gastrointestinal disease in calves that ingested Titya abstersa caterpillars. The outbreak affected 6 of the 40 calves raised in an extensive system, with a mortality rate of 15%. The clinical signs included anorexia, hypersalivation, ruminal bloat, fever (39.8-40.5°C), polydipsia, and gastric reflux. Death occurred within 24 to 48 hours after the onset of the clinical signs. Macroscopic and microscopic findings revealed necrotic rumenitis, reticulitis, esophagitis, and longitudinal and transverse sections of golden structures with backward-facing barbs, consistent with intralesional caterpillar setae. This study aimed to characterize the clinical, epidemiological, and pathological aspects from the necropsies of 3 affected calves. To date, there have been no similar reports regarding the ingestion of T. abstersa caterpillars.

Background: Based on human studies, surgical antimicrobial (AMD) prophylaxis (SAP) beyond 24 h is unnecessary and potentially detrimental.

Objective: To compare clinical and microbiological outcomes in patients receiving 24- or 72-h of SAP for colic surgery.

Study design: Prospective randomised clinical trial.

Methods: Horses that recovered from colic surgery were considered. Exclusion criteria were (1) age <2 years; (2) Miniature Horses, pony, and draught breeds; (3) azotaemia; (4) recent hospitalisation, colic surgery, or AMDs; (5) local AMD administration. Eligible horses were randomly assigned to receive SAP with potassium penicillin and gentamicin for 24- or 72-h. Clinical data and complications were compared between SAP groups. Admission and discharge faecal samples from a subset of horses (N = 49) underwent shotgun metagenomic sequencing on an Illumina platform. Host reads were filtered by aligning to reference genomes using the Burrows-Wheeler Aligner, and taxonomic classification was performed with kraken2. Sequencing reads were aligned to the Comprehensive Antimicrobial Resistance Database (CARD)5 and characterised using the AMR++ pipeline. The microbiome/resistome was characterised and compared between SAP groups over time.

Results: One hundred and forty horses completed the study (24-h N = 71 and 72-h N = 69). The only clinical variable that was different between SAP groups was age (24-h median age 16 [IQR 9, 20] and 72-h 12 [6, 18] years, p = 0.03). There was no significant difference between groups for any complications including incisional infection (24-h 17 [95% CI 10-27]% and 72-h 16 [9-26]%, p = 0.9). Time was the main driver of changes in the microbiome/resistome: alpha diversity decreased while AMD resistance genes associated with administered AMD increased between admission and discharge. Discharge beta-lactam resistance genes were significantly higher in the 72-h than the 24-h group.

Main limitations: Single hospital, small numbers for complications, clinicians not blinded to SAP group.

Conclusions: SAP for 24-h is recommended for horses undergoing colic surgery.

The study of population dynamics in a vertical forest gradient provides basic information on the aspects of insect vector natural history that influence the rate of pathogen transmission. In Mexico, these studies are remarkably limited for sand flies recognised as Leishmania vectors. This study analyses the temporal dynamics of sand fly species (Diptera: Psychodidae) along vertical strata of a tropical dry forest in Yucatán, Mexico, an area previously identified as a transmission hotspot for Leishmania mexicana. Bimonthly samplings were conducted over 1 year by using six CDC light traps in the understory and six traps in the canopy. During the collection period, forest attributes and environmental data (temperature and relative humidity) were recorded for each ecotope. In total, 630 individuals were sampled, of which 68% were collected in the understory and 32% in the canopy. No significant differences in species diversity and abundance were detected between the two ecotopes. Psathyromyia shannoni (Dyar) and Dampfomyia deleoni (Fairchild and Hertig) were the only species structured in the vertical dimension. Observed diversity in both strata responds similarly across both monthly and seasonal time scales. Data analyses indicated that relative humidity influenced the vertical distribution of P. shannoni and D. deleoni, although the magnitude and direction of this effect varied by species. Psathyromyia shannoni exhibited contrasting responses to relative humidity between the canopy and the understory, independent of sex, suggesting that additional environmental factors not assessed in this study may modulate its vertical distribution. Despite the limitations of our work, these findings contribute to the knowledge on the population dynamics of sand flies in the tropical forests of the Yucatán Peninsula.

Records of infections by Leishmania spp. (Kinetoplastida: Trypanosomatidae) have been occurring in the last decade in Sergipe, Brazil. The capital, Aracaju, alone accounted for 44% of the total cases of the state for the visceral form between 2007 and 2016, with high numbers also in other municipalities that make up the metropolitan region. In this sense, this work aimed to carry out entomological surveillance actions in the municipalities of the Metropolitan Region of Aracaju and evaluate the characteristics of the peri-domestic environments that contribute to the maintenance of species richness and abundance. Entomological captures were carried out between 2021 and 2022 with Centers for Disease Control and Prevention (CDC)-type traps for three consecutive nights between twilight and dawn at the beginning of the dry and rainy periods in the peri-domestic area of residences in neighbourhoods peri-urban in the municipalities in the metropolitan region: Aracaju, Barra dos Coqueiros, Nossa Senhora do Socorro and São Cristóvão. The characteristics around the houses were also recorded in a field diary. Constancy, dominance for all species, the household infestation rate and the relative abundance index of the vector for epidemiologically interesting species were calculated. Chi-square tests and multivariate analyses of variance were also performed to search for associations between the vectors and aspects of the dwellings. In total, 752 phlebotomines were captured at 64 collection points. Seven species of phlebotomines were identified, including Lutzomyia longipalpis (Lutz & Neiva, 1912), Evandromyia lenti (Mangabeira, 1938) and Migonemyia migonei (França, 1920). The vector Lu. longipalpis was the species that showed the highest infestation in residences. The results also reveal a sex-specific association influenced by vegetation size, suggesting that denser vegetation may promote male aggregation, a behavioural trait that could be explored in the development of targeted vector control strategies. No significant association was recorded between abundance and environmental factors, which may be related to the difficulty of measuring this association in a heterogeneous environment with so many anthropic interferences in the urbanisation process. By evidencing the influence of ecological factors such as vegetation size on vector behaviour, this study offers insights to enhance leishmaniasis control strategies in Sergipe.

Species belonging to the genus Lipoptena have received limited attention and have historically been subject to misidentifications. Recent records of L. fortisetosa in Europe have rekindled interest in these hippoboscids, leading to the discovery of a new species in Spain in 2024, which has been named L. andaluciensis. During an opportunistic sampling conducted in March 2023 and October 2024 on the Italian red deer (Cervus elaphus italicus), an Italian endemic subspecies, within the ancient relict lowland forest of the Bosco della Mesola Nature Reserve, hippoboscids morphologically identical to L. andaluciensis were collected and examined. This represents the first record of this species in Italy. In total, 257 specimens of Lipoptena were collected and analysed (161 in 2023 and 94 in 2024), all identified as L. andaluciensis. Additionally, Lipoptena specimens collected from fallow deer in 2007 within the same nature reserve, which had remained unidentified until now, were re-examined. A total of 66 specimens were reassessed, of which 63 were morphologically identified as L. andaluciensis and 3 as L. cervi. Morphological identification of the 2023 and 2024 specimens was further confirmed through molecular analysis using COI as a barcode marker. Molecular analysis also revealed the presence of a nuclear copy of the COI gene (NUMTs) in the nuclear genome of L. andaluciensis. The discovery of L. andaluciensis in Spain and in Italy since 2007 raises the possibility that this species has a much broader distribution, particularly at lower altitudes and within a Mediterranean climatic zone. It is plausible that its presence has so far gone unnoticed or has been misidentified.

Ticks are significant vectors of pathogens affecting both animals and humans, with the climate and environment of Sub-Saharan Africa providing ideal conditions for their growth. However, there are limited data on ticks and tick-borne pathogens (T&TBPs) in cattle in The Gambia. This study aimed to identify tick species on cattle and conduct molecular screening for T&TBPs. A total of 92 ticks were collected from 306 indigenous cattle. Ticks were first identified morphologically using taxonomic keys and then confirmed molecularly through DNA sequencing. DNA was extracted from the right fourth leg of six representative ticks for species confirmation, while 77 whole adult ticks were used for screening T&TBPs. Screening polymerase chain reaction (PCR) assays targeted Anaplasma marginale msp1β gene, Ehrlichia spp. dsb gene and hemotropic Mycoplasma spp. 16S rRNA gene. Ehrlichia-positive samples underwent additional assays targeting the sodB, 16S rRNA and groEL genes, followed by Sanger sequencing and phylogenetic analyses. A total of 92 (53 M, 37 F and two nymphs) ticks were collected from 30/306 (9.8%; 95% confidence interval [CI]: 5.6%-12.2%) cattle. Adult ticks were identified as Hyalomma marginatum (73/92; 79.3%; 45 M and 28 F), Amblyomma variegatum (8/92; 8.7%; 8 M), Hyalomma rufipes (4/92; 4.3%; 4 F) and Rhipicephalus evertsi (1/92; 1.1%; one F). The 16S rRNA sequences of six (four engorged female and two nymphs) ticks showed 98.6-100% identity with reference sequences from Rhipicephalus geigyi. Twelve out of 77 (15.6%) ticks tested positive for at least one TBP. Eight H. marginatum (six M and two F) (10.4%) were positive for Ehrlichia spp. dsb gene, three H. marginatum (two M and one F) (3.9%) for A. marginale and two (one H. marginatum F and one A. variegatum M) (2.6%) for hemotropic Mycoplasma spp. All Ehrlichia-positive samples showed 100% detection for the 16S rRNA gene and 62.5% for the sodB gene. BLASTn analysis revealed 99.3%-99.7% identity with Ehrlichia sp. from Brazil and 98.2%-99.3% identity with E. minasensis from Panama and Pakistan. Phylogenetic analysis grouped the sequences from this study with Ehrlichia spp. and E. minasensis from ticks in the Czech Republic and Brazil. This study identified various tick species and pathogens in cattle from The Gambia, including the first report of E. minasensis, A. marginale and hemotropic Mycoplasma spp. in the country. These findings highlight the importance of ongoing surveillance and research on tick-borne diseases in the region.