Evaluation of Control Program Against Streptococcus agalactiae Infection in Dairy Herds During 2019–2021 in Emilia-Romagna Region, Northern Italy

Abstract

Streptococcus agalactiae (group B Streptococcus, GBS) is a causative agent of mastitis in dairy cattle, mainly causing a subclinical disease associated with a high somatic cell count (SCC), and a consequent decrease in production yield and quality of milk. GBS has been almost eradicated in many Northern European countries, but there are warnings of its re-emergence as a zoonotic threat. In Italy, only two regions carry out a GBS control program: Lombardy and Emilia-Romagna. In Emilia-Romagna, the program has been in place since 2019 and provides for the bacteriological culture of bulk-tank milk (BTM) of all dairy farms every 6 months and the voluntary application of herd eradication programs in the case of positive results. To assess the progress of the program in Emilia Romagna, in terms of herd-level prevalence and GBS transmission between herds, we analyzed the results of 17,056 BTM cultures from 2,831 dairy herds, sampled bi-annually in the period 2019–2021 (six rounds total). The impact of GBS infection on SCC and milk production was also evaluated. The results show a decreasing trend in both the incidence rate (from 3.0 to 1.5%) and apparent prevalence (from 8.9 to 5.2%) of GBS over the study period. By using a susceptible-infected-susceptible (SIS) model for the estimation of the transmission parameters, a basic reproductive number R0 of 1.4 was calculated, indicating an active spread of GBS in the dairy cattle population of the Emilia-Romagna region. GBS infected farms have a consistently higher BTM SCC than negative ones (+77,000 cells/ml), corresponding to a 0.4 kg/cow/day milk loss. Moreover, GBS infected herds resulted in almost three times more likelihood of having non-marketable milk by exceeding the legal SCC limit. This study demonstrates the need to maintain the current control program against GBS to lower its occurrence and prevent significant market losses to farmers.

Comparative meta-analysis of antimicrobial resistance from different food sources along with one health approach in Italy and Thailand

“…It not only reduces economic profit owing to milk losses and therapy costs, but it also has a substantial impact on animal health and welfare. [ 67 , 68 ] Pigs are the principal reservoir of Yersinia enterocolitica (about 0.58%) and According to epidemiological research, the principal source of human infections is undercooked pork and other pig products and transported by infected finishing pigs. From farms to slaughterhouses , Y. enterocolitica has been found.…”

Health concerns about possible long-term effects of legally marketed milk and dairy from animals with intramammary infections

“…The milk of these animals is part of the commercialized bulk milk as long as legal standards are met. Within a control program to manage mastitis from Streptococcus agalactiae infections, carried out in the Emilia-Romagna Region, in Italy, during 2019–2021, 17,056 bulk tank milk samples from 2,831 dairy herds were evaluated for SCC and the presence of Streptococcus agalactiae ( 19 ). Within these samples, there were marketable samples with an average SCC of 324,526 cells/ml, which were Streptococcus agalactiae positive.…”

Molecular Characterization of Staphylococcus aureus Isolated from Raw Milk and Humans in Eastern Tanzania: Genetic Diversity and Inter-Host Transmission

“…S. aureus is also the leading cause of mastitis, one of the most important and economically costly infections in dairy cattle [ 3 ]. The success of S. aureus as a pathogen might have emerged as a result of massive control programs against Streptococcus agalactiae , a bacterium associated with subclinical mastitis, resulting in low milk quality and low yield [ 4 ]. The elimination of Streptococcus agalactiae in dairy production farms has notably facilitated the rise of S. aureus , which similarly causes subclinical infections associated with permanent production losses and is very difficult to cure [ 3 ].…”