The first report of concurrent infection of hemorrhagic septicemia with foot and mouth disease in cattle in Bangladesh.

This study aimed to investigate the concurrent infection of Pasteurella multocida (P. multocida) type B:2, which causes Hemorrhagic Septicemia (HS), with cases of Foot and Mouth Disease (FMD) outbreaks in cattle in Bangladesh between March and December 2023. Samples were collected from 11 distinct outbreak areas, totaling 102 samples. These included 54 FMD samples (saliva, tissue epithelium, and morbid tissues such as lung, spleen, and heart) and 54 HS samples (nasal swabs and morbid tissues) from 50 cattle of various ages and sexes, all showing clinical signs of suspected concurrent HS and FMD infection. After sample processing, molecular detection of FMDV and its serotypes was performed using Reverse Transcriptase PCR (RT-PCR) with universal and serotype-specific primers. The HS-causing agent, P. multocida type B:2, was initially identified through cultural and morphological characteristics on various media, followed by Gram's and methylene blue staining, biochemical tests, and pathogenicity tests through inoculation of isolates into mice. Finally, molecular detection of P. multocida type B:2 was confirmed using PCR with specific primers. Forty-five (83 %) of the 54 FMD suspected samples tested positive for FMDV, with 53 % of these positive for serotype 'O,' 17 % for serotype 'A,' and 6 % for mixed serotypes 'O' and 'A.' Among the FMDV-positive samples, 17 (38 %) of the HS-suspected samples tested positive for concurrent infection with P. multocida type B:2. The study reveals that FMDV-induced acute immunosuppression in cattle can lead to complications from concurrent infections, particularly those caused by P. multocida type B:2, resulting in HS alongside FMD.