Epidemiological Study of Lumpy Skin Disease Outbreaks in Egypt Based on Viral Isolation and Molecular Detection
Epidemiological Study of Lumpy Skin Disease Outbreaks in Egypt Based on Viral Isolation and Molecular Detection
Hend E.M. Elsheikh1*, Mamdouh F. El-Mekkawi1, A.A. Abou-Zaid1 and
Amal M. Abd El Raof2
ABSTRACT
Lumpy skin disease (LSD) is among the most significant poxvirus diseases that affect livestock, with high morbidity but low mortality. The disease spreads in various climatic zones, including Africa, Asia, and Europe, causing substantial economic losses in the animal industry. This study aimed to investigate the epidemiological state and risk factors for LSD virus (LSDV) in the six governorates of Egypt (Al-Menia, Alwady ALgaded, Al-Bhera, Al-Dakahlia, Al-Menofia, and Al-Sharqia), based on viral isolation and molecular detection. The required data were collected using a pre-structured questionnaire during fieldwork. This study examined 575 cattle from 25 herds during the LSD outbreak from June 2020 to May 2022. Approximately 185 of 575 cows showed typical LSDV clinical signs that varied from mild to serious. Diseased animals had fever, anorexia, and decrease milk yield, as well as superficial lymph nodes expansion, the sudden appearance of several nodules varying in size from 0.5 to 6 cm in diameter, and numbers according to infection severity. The infected calves displayed serious signs of illness, such as extensive skin lesions and respiratory manifestations. The morbidity, mortality, and case fatality rates were 32.5% (187/575), 6.1% (35/575), and 18.7% (35/187), respectively. There was no significant difference in disease occurrence between different age groups, but animals aged <1 year revealed high mortality. The analysis confirmed that the Holstein breed, females, summer season, and communal water and feeding system all have a major impact on LSD occurrence in cattle. To control the spread of LSD infection, introducing of new animals into the herd must be monitored and vaccination by Neethling strain is recommended. Conventional PCR rely on the EEV Glycoprotein gene is more accurate, sensitive, and time-efficient for LSDV diagnosis than virus isolation on CAM of embryo chicken eggs. As 62 of 81 (76.5%) from skin nodule biopsies and nasal swabs samples showed characteristic Pock lesions when inoculated on CAM of embryo chicken eggs while 39 of 40 (97.5%) of the samples tested positive for LSDV depending on partial amplification of the EEV glycoprotein gene (958-bp) in conventional PCR.
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