Molecular identification and risk factor analysis of the first Lumpy skin disease outbreak in cattle in Mongolia.

Lumpy skin disease (LSD) is a transboundary viral infectious disease in cattle caused by a Capripoxvirus. LSD has been recently introduced in some Asian countries. However, in Mongolia, no report of LSD is publicly available. We clinically examined LSD symptoms in 1,034 cattle from 4 soum (district) in Dornod province in Mongolia. Sixty-one cattle of them were confirmed with symptoms of LSD and then viral P32 gene was detected by a PCR. The overall prevalence of LSD in cattle was 5.9%. Females odds ratios (OR)=2.27 than males, adults (>2.5-years-old, OR=3.68) than young (1-2.5-years-old) and calves (<1-year-old) were at higher risks for LSD cases in Mongolia, while locations near the tube well and pond water are major risk areas for viral transmission due to density of insects often is high. For virus isolation, skin nodule tissue samples of 4 cattle located in four distinct soums were used for viral propagation using the MDBK cell line. Internal terminal repeat region and RPO30 gene of 4 Mongolian isolates were amplified and sequenced. In the phylogenetic trees, Mongolian LSDVs (2021) were clustered together with the Chinese (2020) and Vietnamese isolates (2020). This is the first report alarming the LSD outbreak in Mongolia that was confirmed by our study. The newly isolated viruses would be a useful base for developing diagnostic tools and inactivated vaccine technology. A large-scale study of LSD is next priority for establishing successful control strategy of further disease outbreak.

Nationwide serological surveillance of non-tsetse-transmitted horse trypanosomoses in Mongolia.

In Mongolia, horses play important roles, not only in livestock production, but also in terms of culture, tradition, and Mongolian beliefs. Although the presence of non-tsetse-transmitted horse trypanosomoses, which are caused by infections with Trypanosoma evansi (surra) and T. equiperdum (dourine), has been reported in the country, whether there is a nationwide epidemic of these infectious diseases is unknown. In the present study, a nationwide surveillance of horse trypanosomoses was performed. The sample sizes for each province, the whole country, and male and female horses were, respectively, 96, 2,400, and 316 and 306. In total, 3,641 samples of horse sera were collected by simple random sampling. The rTeGM6-4r-based ELISA, which was applied for surra against cattle and water buffalo and dourine against horse, revealed that the overall sero-prevalence of the diseases in Mongolia was 4.8%. Among them, high sero-prevalences were observed in the central provinces (5.2-11.0%, p < 0.05) of the country. The sero-prevalence was significantly higher in females than in males (6.0% and 4.0%, p < 0.05, respectively) and in non-castrated males (8.4%, p < 0.01) compared with castrated males (3.0%). These results suggested that currently, horse trypanosomoses are a nationwide endemic problem in Mongolia. Knowledge of the nationwide endemic status of non-tsetse-transmitted horse trypanosomoses in Mongolia will be useful to prevent these diseases.

Polyradiculoneuropathy in dourine-affected horses.

Dourine is an equine protozoan disease caused by Trypanosoma equiperdum. Dourine-afflicted animals die after developing neurological clinical signs, such as unilateral paresis. The disease has been a problem for many years; however, the pathogenesis regarding the neurological clinical signs of dourine has been unclear. In the present study, we conducted a histopathological examination in order to investigate the mechanisms by which dourine-afflicted horses develop the accompanying neurological clinical signs. Four dourine-afflicted horses in Mongolia were evaluated. An apparently healthy horse exhibited multifocal neuritis without axonal or myelin degeneration. The other horses, which had obvious neurological clinical signs, also exhibited multifocal neuritis. In particular, the nerves that innervated areas associated with neurological clinical signs exhibited neuritis with demyelination in the latter horses. Inflamed, non-demyelinating nerves were infiltrated with B lymphocytes and T lymphocytes; while inflamed, demyelinating nerves were infiltrated with mononuclear phagocytes. Our observations revealed lesion progression in the nerves, such that polyradiculoneuropathy could explain the accompanying neurological clinical signs of dourine. To our knowledge, this is the first report to describe a pathogenic mechanism for the development of the neurological clinical signs found in dourine-afflicted horses.