Epidemiological situation of Herpesvirus infections in buffalo herds: Bubaline Herpesvirus1 or Bovine Herpesvirus1?

Information on the distribution and related epidemiological characteristics of herpesvirus infections, and in particular referring to Bovine Herpesvirus 1 (BoHV1) and Bubaline Herpesvirus 1 (BuHV1) in buffaloes, have to date not been reported. Different studies based on serological surveys and viral isolation describe the circulation of both infections in this species. The specific etiological attribution of the infections in sero-surveys can be uncertain because of antigenic cross-reactivity of these ruminant α-herpesvirus and therefore depends on the diagnostic techniques employed. For this , we proceeded in verifying the diffusion of the two infections in a buffalo population of Central Italy. The sample size for the number of herds to test was defined considering an expected prevalence > 20% and the number of heads to be tested within each herd was established using an expected prevalence of > 25% (absolute precision of 5%, with 95% confidence level). The 155 herds to test were those with no IBR vaccination history. A maximum of 15 random blood samples were collected within the >3 year age category. The same sampling criteria was adopted when cows were present on buffalo farms to study the possible role of this species. Through the combined use of gB-gE Elisa tests, we assigned a specific infection status, for the BuHV1 infection status (gB-pos/gE-neg), as confirmed by an experimental infection conducted by us inoculating buffaloes with the BuHV1 “strain Metzler”, and for the BoHV1 status (gBpos/ gE-pos) as that observed for the infection in bovines. Prevalence of infection, based on the Elisa status of each animal, were estimated for the whole sample and within each herd. Furthermore, the selected farms were investigated for their numeric consistency, presence of bovines, occurrence of typical clinical herpesvirus disorders occurring during the year prior to sampling. The association of these factors with the infection status was verified using logistic linear regression models. Prevalence for all infection status were observed at population level with no statistical difference between them, while the highest prevalence obtained at herd level was that for the co-existence of the two infections within the same herd. From the linear regression analysis, only the numeric consistency was associated with herds positive for BuHV1 and BoHV1 infection. Concomitance of the two herpesvirus infection in buffaloes as well as in bovine herds should be kept in focus both in their diagnosis as well as in their control.