Targeted pre-partum strategies to suppress Toxocara vitulorum hypobiotic larvae: Reducing transmission to calves and genotypic insights into buffalo infections.

Background and aim: Toxocara vitulorum infections in lactating buffaloes pose significant health and economic challenges due to maternal transmission of inhibited larvae to calves via colostrum and milk. This study aimed to identify T. vitulorum species morphologically and genetically and to evaluate a novel strategic treatment using fenbendazole to suppress larval transmission.

Materials and methods: Morphological and genetic characterization of Toxocara species was performed using light and scanning electron microscopy and mitochondrial COX-1 gene analysis. Pregnant buffaloes previously infected with T. vitulorum were administered fenbendazole (10 mg/kg body weight) 15 days before parturition (dbp). The animals were divided into three groups based on the interval between treatment and parturition: 6 days (G-1), 10 days (G-2), and 15 days (G-3). Colostrum, milk, and fecal samples were collected to assess larval and egg counts, respectively.

Results: The genetic analysis confirmed the species as T. vitulorum with 100% nucleotide similarity to reference sequences. The treatment effectively suppressed larval transmission in G-1, with no larvae detected in colostrum or milk, and significantly reduced larval counts in G-2 and G-3. Fecal egg counts of treated buffaloes and their calves were markedly lower than untreated controls. Statistically significant reductions in worm burden were observed, particularly in the group treated 6 dbp.

Conclusion: A single dose of fenbendazole administered 6 dbp effectively interrupted the T. vitulorum transmission cycle, reducing larval presence in colostrum and milk and minimizing worm burdens in buffaloes and calves. Morphological and molecular analyses highlighted the efficacy of COX-1 gene markers in species identification and phylogenetic studies. This strategic intervention represents a practical approach to controlling T. vitulorum infections, improving herd health, and reducing environmental contamination.