Transboundary Emerging and Exotic Animal Disease/ Exotic Animal Disease Practice Exam

What transmission method is demonstrated when lambs are infected through colostrum from their mothers?

1. Horizontal transmission

2. Indirect contact

3. Vertical transmission

4. Vector-borne transmission

The correct answer is: Vertical transmission

The transmission method demonstrated when lambs are infected through colostrum from their mothers is vertical transmission. This type of transmission explicitly refers to the transfer of pathogens from a parent organism to its offspring, either in utero, during birth, or through breastfeeding, which in this case is represented by the transfer of colostrum. Colostrum is the first form of milk produced by mammals immediately following delivery, rich in antibodies and essential nutrients. When lambs ingest colostrum that contains pathogens from their mothers, they become infected directly through this maternal source. The process underscores the significance of maternal immunity but also highlights a direct route for disease propagation between generations. Horizontal transmission, in contrast, involves the spread of disease between individuals in the same generation, typically through direct contact, airborne routes, or contamination of shared environments, which is not applicable in this context. Indirect contact would involve an intermediary (such as fomites or environmental sources), and vector-borne transmission specifically refers to diseases spread through vectors like insects, neither of which relate to the transmission through colostrum.