Pathological Characteristics of Domestic Pigs Orally Infected with the Virus Strain Causing the First Reported African Swine Fever Outbreaks in Vietnam.

African swine fever (ASF) is currently Vietnam's most economically significant swine disease. The first ASF outbreak in Vietnam was reported in February 2019. In this study, VNUA/HY/ASF1 strain isolated from the first ASF outbreak was used to infect 10 eight-week-old pigs orally with 103 HAD50 per animal. The pigs were observed daily for clinical signs, and whole blood samples were collected from each animal for viremia detection. Dead pigs were subjected to full post-mortem analyses. All 10 pigs displayed acute or subacute clinical signs and succumbed to the infection between 10 to 27 (19.8 ± 4.66) days post-inoculation (dpi). The onset of clinical signs started around 4-14 dpi. Viremia was observed in pigs from 6-16 dpi (11.2 ± 3.55). Enlarged, hyperemic, and hemorrhagic lymph nodes, enlarged spleen, pneumonia, and hydropericardium were observed at post-mortem examinations.

Detection and genetic characterization of canine distemper virus isolated in civets in Vietnam.

Canine distemper (CD), caused by the canine distemper virus (CDV), is a lethal systemic disease to a wide range of wild and domestic carnivorous hosts, including civets. In this study, a possible CD outbreak in a backyard farm with 32 diseased civets (Viverricula indica) in Hanoi, Vietnam, was investigated. The sick civets showed CD-like clinical signs such as anorexia, sedentary behavior, diarrhea, dermatitis, nasal, and footpad hyperkeratosis. Various tissue samples collected from the dead civets were utilized for molecular screening of CDV and histopathological examination. The genetic detection and characterization confirmed that samples collected from dead civets tested positive for CDV. The phylogenetic analysis based on the full-length H gene sequences indicated that all CDV strains isolated from civets belonged to the Asia-1 lineage and were closely related to the CDV strains previously reported from dogs in Thailand, China, and Vietnam. Histopathological examination showed severe interstitial pneumonia, hemorrhagic alveolar septa, necrotic alveolar epithelial cells, necrotic, degenerated, or lost Purkinje cells, eosinophilic intracytoplasmic inclusion bodies, edema, and perivascular cuff. This study confirmed the detection of CDV in civets for the first time in Vietnam.

Molecular and histopathological characterization of lumpy skin disease in cattle in northern Vietnam during the 2020-2021 outbreaks.

Lumpy skin disease (LSD) is a serious emerging infectious disease in cattle caused by a virus of the family Poxviridae. According to the Department of Animal Health, LSD first occurred in Vietnam at the end of October 2020 in Cao Bang and Lang Son provinces. So far, the disease has infected over 63,000 animals, resulting in 9170 deaths occurring in 32 different provinces in northern and central Vietnam. In this study, skin samples from lumpy skin disease virus (LSDV)-infected cattle from the northern provinces of Vietnam displaying clinical symptoms including fever (> 40 °C), runny nose, drooling, and skin lesions were used for genetic characterization and histopathology. Genetic analysis of the partial P32 (LSDV074), partial F (LSDV117), complete RPO30 (LSDV035), and complete G-protein-coupled-chemokine-like receptor (GPCR) (LSDV011) genes showed that all Vietnamese LSDV strains belonged to the genus Capripoxvirus and were closely related to LSDV strains isolated in China. Microscopic examination of the skin lesions showed thickening of the epidermal layer of the skin and hair follicles, hyperplasia of sebaceous glands, intracytoplasmic inclusion bodies, and hemorrhages in the mesoderm.