Assistant Laboratory Animal Technician (ALAT) Practice Exam

If an animal is exposed to a pathogen while in transit to a research facility, typically how long is it before the animal will test positive for the pathogen?

1. 1 to 2 weeks

2. 5 to 7 weeks

3. 3 to 4 weeks

4. 2 to 3 weeks

The correct answer is: 3 to 4 weeks

When an animal is exposed to a pathogen, the time it takes for that animal to test positive is influenced by the pathogen's incubation period, which is the time between exposure and the onset of detectable infection. Some pathogens have relatively short incubation periods, while others may take longer. In many cases, particularly for a range of common pathogens, the timeframe of 3 to 4 weeks is consistent with the typical incubation periods seen in various species used in research settings. Testing for pathogens often relies on the presence of antibodies or the pathogen itself, and within this timeframe, enough time has elapsed for the animal’s immune system to react and for detectable changes to occur. Choosing a response that indicates a shorter timeframe, such as 1 to 2 weeks or even 2 to 3 weeks, may not account for the fact that some infections may require a bit longer for clinical manifestations and antibody production to be observed reliably. Similarly, a longer timeframe of 5 to 7 weeks also overestimates the typical response observed for many pathogens when considering their common incidence in laboratory animal populations. Therefore, the 3 to 4-week period aligns best with general scientific knowledge regarding pathogen exposure and the observable effects in laboratory animals.