An outbreak of visna-maedi in a flock of sheep in Southern Brazil

Cecco, Bianca Santana de; Henker, Luan Cleber; Lorenzett, Marina Paula; Molossi, Franciéli Adriane; Schwertz, Claiton I.; Baumbach, Leticia Ferreira; Weber, Matheus Nunes; Canal, Cláudio Wageck; Driemeier, David; Pavarini, Saulo P.; Langohr, Ingeborg M.; Carossino, Mariano; Balasuriya, Udeni B. R.; Sonne, Luciana

doi:10.1007/s42770-022-00763-9

Cited by 4 publications

(6 citation statements)

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“…In general, MVV strains are more pathogenic in sheep while CAEV strains are more pathogenic in goats. The most prevalent form of disease in sheep infected with MVV (genotype A) is respiratory; however, genotype-C viruses can also cause lung lesions in sheep ( 30 ). Maedi-visna virus–like strains can occasionally cause arthritis, as described by some authors ( 119 ).…”

Section: Tropism and Pathologymentioning

confidence: 99%

The genetic variability of small-ruminant lentiviruses and its impact on tropism, the development of diagnostic tests and vaccines and the effectiveness of control programmes

Olech

2023

Journal of Veterinary Research

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Introduction Maedi-visna virus and caprine arthritis encephalitis virus are two closely related lentiviruses which cause multisystemic, progressive and persistent infection in goats and sheep. Because these viruses frequently cross the species barrier, they are considered to be one genetic group called small-ruminant lentiviruses (SRLV). They have in vivo tropism mainly for monocytes and macrophages and organ tropism with unknown mechanisms. Typical clinical signs are pneumonia in sheep, arthritis in goats, and mastitis in both species. Infection with SRLV cannot currently be treated or prevented, and control programmes are the only approaches to avoiding its spread. These programmes rely mainly on annual serological testing and elimination of positive animals. However, the high genetic and antigenic variability of SRLV complicate their early and definitive diagnosis. The objective of this review is to summarise the current knowledge of SRLV genetic variation and its implications for tropism, the development of diagnostic tests and vaccines and the effectiveness of control and eradication programmes. Material and Methods Subject literature was selected from the PubMed and the Google Scholar databases. Results The high genetic diversity of SRLV affects the performance of diagnostic tools and therefore control programmes. For the early and definitive diagnosis of SRLV infection, a combination of serological and molecular tests is suggested. Testing by PCR can also be considered for sub-yearling animals. There are still significant gaps in our knowledge of the epidemiology, immunology and biology of SRLV and their impact on animal production and welfare. Conclusion This information may aid selection of the most effective SRLV spread reduction measures.

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Section: Tropism and Pathologymentioning

confidence: 99%

The genetic variability of small-ruminant lentiviruses and its impact on tropism, the development of diagnostic tests and vaccines and the effectiveness of control programmes

Olech

2023

Journal of Veterinary Research

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“…Cecco et al disease and economic losses. In sheep, although there are several reports of VMV seroprevalence in many regions, demonstrating very low seroprevalence of the virus in sheep flocks, only one outbreak of the clinical disease was described recently in south Brazil (CECCO et al, 2022). A moderate seroprevalence (30-60%) of VMV infection in flocks in the United Kingdom correlates with low mortality but a substantial subclinical disease (BRODIE et al, 1998).…”

Section: Visna-maedi Etiology and Epidemiologymentioning

confidence: 99%

“…The nervous form, visna, frequently leads to stumbling, ataxia, and blindness, followed by hindlimb paralysis. Total recumbency is observed in the final stages of the disease (BENAVIDES et al, 2006b;CECCO et al, 2022). Mastitis caused by VMV is common; although, frequently subclinical, leading to important financial and epidemiological consequences since milk and colostrum can be a source of infection in newborns.…”

Section: Clinical and Pathological Findingsmentioning

confidence: 99%

“…A diffusely rubbery texture and occasional scattered foci of consolidation are observed. On rare occasions, gross lesions in the brain can be seen as softening of the periventricular or funicular white matter (Figure 5C) (leukomalacia) or as a granular appearance of the choroid plexus (BENAVIDES et al, 2009;VANDEVELDE et al, 2012;CECCO et al, 2022). Spinal cord lesions are rare and, at the gross examination, after transverse sectioning, consist of swollen, discolored wedge-shaped areas (BENAVIDES et al, 2006a).…”

Section: Clinical and Pathological Findingsmentioning

confidence: 99%

“…The mammary gland exhibits a periacinar diffuse interstitial infiltration of lymphocytes that often surround ducts, in addition to intense fibrosis, leading to profound changes in the normal acinar structure and effacing acinar epithelial cells (Figure 5E). In the neurological form, histologic changes include lymphoproliferative choroiditis and a nonsuppurative, granulomatous to necrotic leukoencephalomyelitis with secondary leukomalacia, periventricular encephalitis with mononuclear perivascular cuffs (Figure 5F), and demyelination, appearing in subependymal areas of the mesencephalon, thalamus, and medulla oblongata (BIESCAS et al, 2005;BENAVIDES et al, 2009;CECCO et al, 2022). Lymphohistiocytic perivascular cuffs and adjacent areas of macrophage infiltration of the neuroparenchyma leading to its destruction have a typical periventricular and periaqueductal distribution (funicular in the spinal cord); although they can progress to a more disseminated distribution (BENAVIDES et al, 2006b).…”

Section: Clinical and Pathological Findingsmentioning

confidence: 99%

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Viral diseases of sheep in Brazil: a review and current status

et al. 2023

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The increase in sheep production is directly related to the health status of the flock. Brazil is one of the largest sheep producers in the world, and the sheep flock is concentrated in southern and northeast regions. Infectious diseases are responsible for severe economic losses resulting from a decrease in milk and meat production, deaths, and cost of treatment. Among infectious diseases, viral diseases are described chiefly in case reports or retrospective studies. This study aimed to review the main features of viral diseases that affect sheep in Brazil and their current situation in the Brazilian territory. We included eight viral diseases described in Brazil: rabies, bluetongue, contagious ecthyma, foot and mouth disease, visna-maedi, enzootic nasal tumor, ovine pulmonary adenocarcinoma, and border disease. We review the etiological, epidemiological, clinical, and pathological findings for each agent and included differential diagnoses, information on recommended diagnostic methods to confirm the disease etiology, and control measures. This study served as quick consultation material for field veterinarians for an accurate diagnosis.

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