Retrospective study of laboratory-based surveillance of rabies in wild and domestic animals in the southern United States, 2010-2021.

We performed a retrospective study of all case submissions for the rabies virus (RABV) direct fluorescent antibody test (DFAT) requested of the Tifton Veterinary Diagnostic and Investigational Laboratory (Tifton, GA, USA) between July 2010 and June 2021. Submitted were 792 samples from 23 animal species from 89 counties in Georgia, and 4 neighboring counties in Florida, 1 in South Carolina, and 1 in Alabama. In 13 (1.6%) cases, the DFAT result was inconclusive; 779 (98.4%) cases had a conclusive (positive or negative) test result. Of these 779 cases, 79 (10.1%) tested positive across 10 species. The remaining 700 (89.9%) cases were negative. The main reason for submission for RABV testing was human exposure to a potentially rabid animal in 414 (52.3%) cases. Among the 79 positive cases, 74 (93.7%) involved wildlife; raccoons (51 cases; 68.9%) were the primary host confirmed with RABV infection, followed by skunk and fox (8 cases each; 10.8%), bobcat (5 cases; 6.8%), and bats (2 cases; 2.7%). Only 5 domestic animals (6.3% of the positive cases) tested positive during our study period; one from each of the bovine, canine, caprine, equine, and feline species. Hence, the sylvatic cycle plays the predominant role in circulating RABV infection in our study area.

Identification of Four Populations of Meloidogyne incognita in Georgia, United States, Capable of Parasitizing Tomato-Bearing Mi-1.2 Gene.

Meloidogyne incognita, the southern root-knot nematode (RKN), is the most predominant plant-parasitic nematode species of tomato and causes significant yield loss. The Mi-1.2 gene confers resistance in tomatoes to M. incognita; however, virulent RKN populations capable of parasitizing resistant tomato cultivars have been reported from different regions in the world. Four naturally occurring virulent populations of M. incognita were found in vegetable fields from four counties in Georgia with no history of tomato cultivation of the Mi gene. Two consecutive greenhouse trials showed that all four virulent RKN populations reproduced on tomato cultivars, including Amelia, Skyway, and Myrtle, with the Mi-1 gene, while an avirulent population of M. incognita race 3 was unable to overcome host resistance. Virulent RKN populations varied in reproduction among resistant cultivars, with Ma6 population having the greatest reproduction potential. No difference in penetration potential of the virulent (Ma6) and avirulent populations was found on susceptible and resistant tomato cultivars. However, virulent Ma6 population females were successful at egg-laying, whereas avirulent female development was arrested in the resistant cultivars. The virulent Ma6 population also induced feeding sites in the roots of resistant cultivars, whereas the avirulent population did not. To our knowledge, this is the first report of resistance-breaking populations of M. incognita in Georgia and the second state in the United States after California.

An outbreak of Neospora caninum abortion in a dairy herd from the State of Georgia, United States.

An outbreak of 92 abortions out of 1,700 pregnant cows (5.41%) in a period of 3 weeks (19 May to 05 June 2019) occurred in a Georgia Dairy, USA, in cattle that were between 3 and 7 months of gestation. Two sets of samples (aborted fetuses' organs, placental tissues, aborted cows blood) were submitted for laboratory investigations at the Tifton Veterinary Diagnostic and Investigational Laboratory, College of Veterinary Medicine, University of Georgia (TVDIL, Tifton, GA, USA). An abortion panel testing for the major abortion-causing agents [e.g. Bovine Viral Diarrhoea Virus (BVDV), Infectious Bovine Rhinotracheitis Virus/ Bovine Herpes Virus-I (IBR/ BHV-I), Brucella spp., Leptospira spp.] was conducted on several of the samples. On the first set of samples, microbial cultures, serology and PCR tests for the common abortifacient agents revealed the presence of Neospora caninum (N. caninum) DNA, which was positive by PCR on the placenta and fetal tissues. The second set of diagnostic investigations also identified two out of three submitted freshly aborted fetuses to be positive for N. caninum by PCR and immunohistochemistry. Moreover, all three dams were also sero-positive for N. caninum. The entire herd was being fed on grass silage harvested from a pasture where feral pigs were hunted previously and carcasses were left behind. As a consequence of this action a large population of wild coyotes were attracted to these carcasses, and likely contaminated the pasture with potential N. caninum-infected feces. After the abortion outbreak was resolved, it was recommended that the farmers should avoid disposal of cadavers of hunted animals in the wild, as it could attract carnivorous and omnivorous animals that may potentially spread the disease to the cattle and other wildlife.

Characterization of Resistance to Major Tropical Root-Knot Nematodes (Meloidogyne spp.) in Solanum sisymbriifolium.

Root-knot nematodes (Meloidogyne spp.) are important contributors to yield reduction in tomato. Though resistant cultivars to common species (Meloidogyne arenaria, M. incognita, and M. javanica) are available, they are not effective against other major species of root-knot nematodes. Cultivars or lines of Solanum sisymbriifolium were examined to assess the presence and level of resistance to five major species: M. arenaria race 1, M. incognita race 3, M. haplanaria, M. javanica, and M. enterolobii. Differences in S. sisymbriifolium response to the nematode infection were apparent when susceptibility or resistance was classified by the egg counts per gram fresh weight of root and the multiplication rate of the nematodes. The cultivar Diamond was highly susceptible, Quattro and White Star were susceptible, while Sis Syn II was resistant to M. arenaria. Quattro, White Star, and Sis Syn II exhibited a moderate to high level of resistance to M. incognita but the nematode increased 2.5-fold from the initial population of the M. incognita on Diamond. All S. sisymbriifolium cultivars were highly resistant to both M. haplanaria and M. enterolobii, while highly susceptible to M. javanica. A microplot study under field conditions using Sis Syn II confirmed that M. arenaria, M. incognita, and M. haplanaria were not pathogenic on the plant. Likewise, an examination on cross-sections of galled root tissues confirmed the susceptibility and resistance of S. sisymbriifolium lines to Meloidogyne spp. Using S. sisymbriifolium as a resistant rootstock or a new source of resistance may result in the development of nonchemical and sustainable management strategies to protect the tomato crop.

Evaluation of Targeted Next-Generation Sequencing for Detection of Bovine Pathogens in Clinical Samples.

The laboratory diagnosis of infectious diseases, especially those caused by mixed infections, is challenging. Routinely, it requires submission of multiple samples to separate laboratories. Advances in next-generation sequencing (NGS) have provided the opportunity for development of a comprehensive method to identify infectious agents. This study describes the use of target-specific primers for PCR-mediated amplification with the NGS technology in which pathogen genomic regions of interest are enriched and selectively sequenced from clinical samples. In the study, 198 primers were designed to target 43 common bovine and small-ruminant bacterial, fungal, viral, and parasitic pathogens, and a bioinformatics tool was specifically constructed for the detection of targeted pathogens. The primers were confirmed to detect the intended pathogens by testing reference strains and isolates. The method was then validated using 60 clinical samples (including tissues, feces, and milk) that were also tested with other routine diagnostic techniques. The detection limits of the targeted NGS method were evaluated using 10 representative pathogens that were also tested by quantitative PCR (qPCR), and the NGS method was able to detect the organisms from samples with qPCR threshold cycle (CT ) values in the 30s. The method was successful for the detection of multiple pathogens in the clinical samples, including some additional pathogens missed by the routine techniques because the specific tests needed for the particular organisms were not performed. The results demonstrate the feasibility of the approach and indicate that it is possible to incorporate NGS as a diagnostic tool in a cost-effective manner into a veterinary diagnostic laboratory.

Significance of cytological smear evaluation in diagnosis of splenic mast cell tumor-associated systemic mastocytosis in a cat (Felis catus).

An 8-year-old cat was presented with vomiting and weight loss. Histopathology and cytology revealed systemic mastocytosis, a rare condition and a clinical challenge. This case emphasizes the significance of cytological evaluation of smears in diagnosis of mastocytosis and in confirmation in biopsy specimens.

Signification de l'évaluation d'un frottis cytologique dans le diagnostic d'une mastocytose systémique chez un chat(Felis catus)associée à une tumeur des mastocytes spléniques. Un chat âgé de huit ans a été présenté avec des vomissements et une perte de poids. L'histopathologie et la cytologie ont révélé une mastocytose systémique, une affection rare et difficile sur le plan clinique. Ce cas met en lumière l'importance de l'évaluation cytologique des frottis pour le diagnostic de la mastocytose et la confirmation pour les spécimens de biopsie.(Traduit par Isabelle Vallières).

First report of vascular invasion of demodex mites with thrombi and dissemination to visceral lymph nodes in a dog.

An adult-onset generalized canine demodecosis is a life threatening form of demodecosis often seen in immunocompromised dogs. A generalized, adult-onset canine demodecosis with an unusual vascular invasion, thrombi and dissemination to peripheral, and visceral lymph nodes was diagnosed in an adult, female, American Bulldog of unknown age. Organized thrombi with intralesional mites were observed in multiple lymphatic vessels and in a section of blood vessel. Vascular invasion of mites with dissemination of mites into visceral lymph nodes, is an unusual findings not previously recorded in canine generalized demodecosis. Dissemination of mites to visceral lymph nodes through vascular channels may be part of the pathogenesis of chronic, untreated, and disseminated, adult-onset generalized canine demodecosis.

Subcutaneous sparganosis, a zoonotic cestodiasis, in two cats.

Sparganosis is a zoonotic cestodiasis of human beings and animals caused by plerocercoid or second-stage larvae (sparganum) of pseudophyllidean tapeworms in host tissues. Cats are among definitive hosts in which the larva develops to adult stage in the intestines. Reports on larval infection involving various tissues and organs in cats are scarce. Rare single case reports of visceral sparganosis in cats are previously documented. The present report documents an unusual subcutaneous sparganosis in 2 Domestic Shorthair cats from southern Georgia. Veterinary clinicians should consider sparganosis as differential diagnosis for subcutaneous cyst-like masses in cats. As infected animals and animal tissues are sources of human infection, sparganosis warrants public awareness and due precaution to avoid human infection.

Detection of asymptomatic renal Leptospira infection in abattoir slaughtered cattle in southeastern Georgia, United States.

OBJECTIVES: Leptospirosis is one of the most widespread zoonotic infectious diseases affecting humans and animals. Several animal species, including cattle, can act as potential asymptomatic carriers facilitating zoonotic transmission of Leptospira. This study was conducted to assess the occurrence of asymptomatic renal Leptospira carriers among cattle slaughtered in southeastern Georgia, United States. METHODS: A battery of diagnostic tests, including dark field microscopy, direct fluorescent antibody staining, polymerase chain reaction, and culture, were performed on a set of bovine kidneys (n = 37) collected from an abattoir in southeastern Georgia, United States. Virulence of a field isolate obtained from this study was tested in a hamster experimental model. RESULTS: Motile spirochete-like structures were observed by dark field microscopy in 23 (59%) out of 37 kidney samples tested. In all, 29 samples (78%) were positive by direct fluorescent antibody staining. Only 11 (29.7%) samples by polymerase chain reaction and 3 (8.1%) by culture were positive for Leptospira sp. The isolates obtained by culture were confirmed as Leptospira borgpetersenii. Hamsters experimentally infected with one of the Leptospira field isolates obtained from this study did not show clinical signs but developed renal infection with interstitial nephritis and tubular necrosis. CONCLUSIONS: This study confirms that asymptomatic Leptospira renal infection is present among cattle in the region. Our findings underscore the need for future studies to assess the potential environmental contamination and transmission to humans in contact with infected cattle.

Tumor microvessel density-associated mast cells in canine nodal lymphoma.

OBJECTIVE: Mast cells are associated in angiogenesis in various human and animal neoplasms. However, association of mast cells with tumor microvessel density in canine lymphoma was not previously documented. The objective of the study is to determine if mast cells are increased in canine nodal lymphomas and to evaluate their correlation with tumor microvessel density and grading of lymphomas. METHODS: Nodal lymphomas from 33 dogs were studied and compared with nonneoplastic lymph nodes from 6 dogs as control. Mast cell count was made on Toluidine blue stained sections. Immunohistochemistry using antibody against Factor VIII was employed to visualize and determine microvessel density. RESULTS: The mast cell count in lymphoma (2.95 ± 2.4) was significantly higher (p < 0.05) than that in the control (0.83 ± 0.3) and was positively correlated with tumor microvessel density (r = 0.44, p = 0.009). Significant difference was not observed in mast cell count and tumor microvessel density among different gradings of lymphomas. CONCLUSIONS: Mast cells are associated with tumor microvessel density in canine nodal lymphoma with no significant difference among gradings of lymphomas. Mast cells may play an important role in development of canine nodal lymphomas. Further detailed investigation on the role of mast cells as important part of tumor microenvironment in canine nodal lymphomas is recommended.

A concise review of amyloidosis in animals.

Amyloidosis refers to a group of protein misfolding diseases characterized by deposition of a particular amyloid protein in various organs and tissues of animals and humans. Various types and clinical forms of amyloidosis, in which the pathology and pathogenesis is diverse depending upon the underlying causes and species affected, are reported in domestic and wild animals. The clinical findings are also quite variable consequent to the variation of the tissues and organs involved and the extent of functional disruption of the affected organs in various animal species. The affected organs may be enlarged and exhibit variable pallor grossly, or the amyloid deposit may be discernible only after microscopic examination of the affected tissues. Amyloid appears as a pale eosinophilic homogenous extracellular deposit in tissues. However, microscopic examination and Congo red staining with green birefringence under polarized light are needed to confirm amyloid and differentiate it from other apparently similar extracellular deposits such as collagen and fibrin. Identifying the type of amyloid deposit needs immunohistochemical staining, ultrastructural characterization of the amyloid fibril, and if feasible also genetic studies of the involved species for clinical and prognostic purposes. This paper provides a concise review of the occurrence of amyloidosis in domestic and wild animals.

Canine parvovirus-2b-associated erythema multiforme in a litter of English Setter dogs.

Erythema multiforme (EM) was diagnosed in a litter of English Setter puppies. The puppies developed erythematous cutaneous lesions at the age of 2 weeks. Microscopically, there was individual keratinocyte apoptosis associated with lymphocyte exocytosis in all layers of the epidermis. Intranuclear viral inclusions were seen in multiple tissues and organs. Tissues from the tongue, lymph node, spleen, skin, and small intestine were positive for Canine parvovirus-2 (CPV-2) and negative for Canine distemper virus (CDV) and Canid herpesvirus 1 by fluorescent antibody test. Negative-staining electron microscopy detected parvovirus particles in the intestinal contents. The skin and small intestine were positive for CPV-2b and negative for CDV by polymerase chain reaction. The mucocutaneous junctions and small intestines stained positive for CPV by immunohistochemistry. The present report documents CPV-2b-associated EM in a litter of English Setters and substantiates the single previous report associating EM with CPV-2. The finding suggests that CPV should be considered as a possible cause of EM in dogs.

Meningoencephalitis caused by Mycoplasma edwardii in a dog.

A 6-week-old, female, mixed-breed dog with a clinical history of sudden onset of neurologic signs was presented for necropsy. The dog was diagnosed with suppurative and histiocytic meningoencephalitis based on necropsy findings and histopathology. Mycoplasma sp. was isolated in pure culture from the brain and meninges and was identified as Mycoplasma edwardii using DNA sequencing.

Mast cells in canine cutaneous hemangioma, hemangiosarcoma and mammary tumors.

Mast cell count (MCC) in 45 dogs with cutaneous hemangioma (HA, n = 12), hemangiosarcoma (HSA, n = 12), mammary adenoma (AD, n = 9) and mammary adenocarcinoma (AC, n = 12) was made using Toluidine blue stained sections. Antibodies against endothelial cell markers, Factor VIII and VEGF were used to visualize and determine the hot spot micro-vessel density (MVD). Total MCC and MCC along the invasive edges were significantly higher (p < 0.001) in canine mammary AC than in AD. The total MCC did not significantly differ (p > 0.05), in HSAs (8.6 +/- 3.3) than in HAs (5.5 +/- 2.8). There is a positive correlation (r = 0.14) between the hot spot MCC and MVD in mammary AC, although not significant (p = 0.3172), indicating that mast cells are associated with angiogenesis in canine mammary AC. This study suggests that mast cells may play an important role in neovascularization of canine cutaneous vascular and mammary neoplasms. Detailed studies encompassing correlation of MCC and MVD with clinical outcomes and prognosis in these neoplasms are recommended.

Feeding Behavior-Related Toxicity due to Nandina domestica in Cedar Waxwings (Bombycilla cedrorum).

Dozens of Cedar Waxwings were found dead in Thomas County, Georgia, USA, in April 2009. Five of these were examined grossly and microscopically. Grossly, all the examined birds had pulmonary, mediastinal, and tracheal hemorrhages. Microscopically, several tissues and organs were diffusely congested and hemorrhagic. Congestion and hemorrhage were marked in the lungs. Intact and partly digested berries of Nandina domestica Thunb. were the only ingesta found in the gastrointestinal tract of these birds. Due to their voracious feeding behavior, the birds had eaten toxic doses of N. domestica berries. N. domestica contains cyanide and is one of the few berries readily available at this time of the year in the region. The gross and microscopic findings are consistent with lesions associated with cyanide toxicity. This paper for the first time documents toxicity associated with N. domestica in Cedar Waxwings.