It is important for a shelter worker to understand the common carrier states of disease so they can best recognize disease and disinfect against disease causing pathogens. The end goal is to prevent an outbreak of disease which can be hard to extinguish once started. Some animals are able to spread a disease before or after the treatment period which is key to understanding how long to limit their contact with other animals so that they do not make other animals sick. Washing your hands or sanitizing your hands is the number one way to reduce the entry of disease.
Animals are able to spread disease even under a vigilant eye which is the number one reason that shelters often have an intake room for new arrivals, an isolation room for cats that are proven to be sick, an adoption room and a quarantine area for potentially sick animals at the minimum. It is smart and ideal to also have a separate room for nursing mother cats, young kittens and cats with injuries to further prevent susceptible animals being near animals who have a better immune system. A daily observation sheet for each animal and for the rescue/shelter as a whole is required.
This is not the article for discussing vaccines but I will briefly mention that every single cat that enters the sheltering system of 6 weeks or older need to be given an FVRCP modified live vaccine on the day they arrive. Not 1 hour later or one day later if you want rapid protection. Pregnant cats, cats with illness or cats under 8 weeks of age with a mother cat are exempt. All vaccines are boostered every 2 weeks until they reach 16 weeks of age then once yearly to close out any potential gaps of being susceptible to infection.
There are quite a few different carrier states of disease that an animal can fall under and the shelter worker should be familiar with all of them or at least the incubatory carrier and convalescent carrier. Some animals will not be easily examined when it comes to their health which is number one reason that all new animals are separated from existing animals for 10 full days. This is to say that I have had quite a few cats that seem healthy on intake and a day later they look like death. It is essential to know each carrier state so you are equipped with the knowledge to work with them the right way and so you can legally protect the shelter if someone complains.
An animal that can spread disease during the incubation period of disease is the most dangerous threat to any shelter. The incubation period of disease is the time after exposure and before clinical symptoms appear so the animal looks healthy but is really brewing an infection. It has been shown that the incubation period is the stage at which the disease is spread the furthest because workers become complacent. A cat with upper respiratory infection can take up to 7-21 days before they exhibit any signs of disease but is still actively spreading it form the day they contracted it.
Any animal who has recovered from a disease but is still capable of transmitting the disease to other animals can be called a convalescent carrier. Dogs with parvovirus can spread this disease up to 35 days post treatment and cats can spread upper respiratory infection for a few weeks after being treated too. I always like to wait 2 weeks after a cat or dog is showing no clinical symptoms before I give the green light for putting them back into general population with the rest of the shelter animals. You really do not want to screw up this part.
A latent carrier is any animal that does not spread the virus regularly on a day to day basis to other animals. Any animal that is stressed or exposed to a very stressful situation can begin to spread the virus again which is the reason that shelters have started to utilize spot cleaning protocols which I will cover in another article. This is referred to as disease recrudesce. This is most commonly seen with feline herpes virus which is mostly stress induced.
An inapparent carrier is when an animal is infectious and shedding, but is not currently showing any real signs of disease. This can also be called an asymptomatic carrier. This can be another dangerous and silent killer of cats and dogs because people tend to become complacent in not following every protocol when animals appear healthy. You want to be proactive instead of reactive.