Hanan El Ouadi

Neonatal calf diarrhea represents a major health and economic burden in Moroccan cattle farming and remains a leading cause of calf mortality. It is commonly associated with infectious agents such as rotavirus, bovine coronavirus, Escherichia coli, and Cryptosporidium parvum, and is often aggravated by dehydration and electrolyte imbalances. The present study aimed to update the epidemiological profile of viral pathogens involved in neonatal calf diarrhea in Morocco, with particular emphasis on rotavirus group A (RVA) and bovine coronavirus (BCoV). A total of 889 newborn calves from 20 farms located in five Moroccan regions (Casablanca-Settat, Rabat-Salé-Kenitra, Souss-Massa, Fes-Meknes, and Beni Mellal-Khenifra) were included in this cross-sectional observational study. Among them, 130 rectal swabs were collected from diarrheic calves between November 2022 and March 2023 and analyzed using reverse transcription quantitative PCR (RT-qPCR). The results indicated that 34% of diarrheic calves tested positive for RVA and 62% for BCoV, with a co-infection rate of 24%. Infection rates were influenced by several factors, including calf age, geographic region, dam vaccination status, calving rank, production system, and farm size. RVA infection peaked in calves aged 8–14 days, whereas BCoV was most prevalent in calves aged 21–29 days. Notably, RVA positivity was higher in calves born to vaccinated dams (40%) compared to those from unvaccinated dams (20%), while BCoV infection was more frequently detected in calves from heifers than from multiparous cows. Higher infection rates in calves were also observed in intensive farming systems. Overall, these findings confirmed the major role of rotavirus and bovine coronavirus in neonatal calf diarrhea in Morocco and suggest that the limited effectiveness of vaccination may be influenced by herd management, colostrum transfer, and biosecurity practices. The potential mismatch between vaccine and circulating strains highlights the need for continuous molecular surveillance.

The research investigates synthetic hydroxytyrosol (HT) antiviral properties against enveloped and non-enveloped viruses using in silico and in vitro methods. Molecular docking and ADMET analyses suggested favorable interactions of HT with ceramide and sphingomyelin (binding energies of −6.0 and −5.9 kcal/mol, respectively). Favorable predicted pharmacokinetics and safety profiles were also observed. In vitro tests provided preliminary evidence of the dose- and time-dependent virucidal effect of HT against several enveloped viruses, including HSV-1, West Nile virus, SARS-CoV-2 and various influenza A subtypes, which resulted in substantial viral load decreases at 1000 µg/mL. The viral titer of the measles virus decreased by 4.62 log₁₀ units during the 2 h of exposure. No virucidal activity was observed against the non-enveloped bovine rotavirus. Overall, these findings suggest that hydroxytyrosol may represent a promising candidate for further investigation as a virucidal agent, particularly against enveloped viruses.

Group A rotavirus commonly infects cattle and results in gastrointestinal disorders that are responsible for heavy losses among these animals and within the livestock industry in general. In Morocco, the G10P[14] and G6P[5] genotypes are frequently observed; however, limited data contribute to restricted vaccine choice and disease control. Preventive measures include effective colostrum management practices, hygiene, and vaccination of pregnant cows to pass on passive immunity to newborn calves. Nevertheless, the effectiveness of vaccines in Morocco has not been ascertained because there has been no proper tracking of local variants and their spread. This narrative literature review presents an updated insight into the bovine rotavirus scenario in Morocco and its impact on animal health and the cattle industry. Epidemiological data on circulating genotypes and vaccine performance remain limited and fragmented at the national level, constraining evidence-based vaccine selection and control strategies. Therefore, epidemiological investigations are recommended to identify circulating strains, along with laboratory and field studies assessing vaccine effectiveness, in addition to improved management practices and farmer education. Therefore, using these evidencebased approaches, productivity losses and the vulnerability of the Moroccan livestock industry can be minimized. This paper goes a long way in demonstrating the need for cross-disciplinary work between researchers, veterinarians, and policymakers that will help translate the findings into practical interventions in fields that not only preserve the health of animals but also the farmers’ income in Morocco’s diverse zones.