First Record of an Outbreak of Dictyocaulus viviparus Infection in Cattle and Buffalo Farms in Assiut, Upper Egypt with Special Reference to the Role of Filth Flies in the Disease Transmission

Bovine dictycaulosis is a serious disease in ruminants caused by lungworm Dictyocaulus viviparous with a wide spectrum of clinical manifestations. The infection is closely related to pasture contamination with the infective larvae. A cross-sectional study was conducted from July 2020 to June 2021 to detect the prevalence of bovine dictyocaulosis in two animal-rearing stations in Assiut, Upper Egypt with risk factor analysis. Also, the role of filth flies in the transmission of infective larvae was investigated. A total of 251 animals (143 cattle and 108 buffaloes) were examined using the modified Baermann technique and postmortem examination. Multiple fly pools were also collected and examined for the detection of Dictyocaulus larvae in different seasons microscopically and by PCR techniques. The overall prevalence of D. viviparus infection in cattle and buffaloes was 20.98% and 52.78%, respectively. The infection was significantly higher in the young aged and symptomatic animals (96.7%). Most lungworm infection was recorded during autumn, spring, and winter seasons, respectively. Coprological examination coincides with microscopic examination of fly wash regarding the prevalence and the seasonal variation. Musca domestica, Borborillus vitripennis, Fannia canicularis, and Sepsis punctum were the most abundant fly species and showed the highest rates of infection. To the authors’ knowledge, this is the first report of an outbreak of bovine dictycauolosis in Upper Egypt. The obtained results proved the role of filth flies in the transmission of D. viviparus larvae during the outbreak. Control programs for bovine dictyocaulosis should include the control of filth flies around the rearing places.