If your pet gets a tick, the tick can stay hidden in its fur for quite a few weeks. That is rather strange: if you leave a splinter in your finger for a few days, it will fester and work itself in that time. Apparently, ticks have a number of biochemical tricks to outdo your immune system.
For example, the tick Ixodes scapularis produces the substance sialostatin in its saliva, which restricts the production of the antibody Interleukin-9, and while that is very useful to the tick, the substance could be used to help people with overactive immune systems.
Leiden lung researcher Christian Taube has been working on an international study into sialostatin, and this study is featured in The Journal of Immunology. It reveals that genetically modified asthmatic mice can breathe more easily when they have been injected with this tick spit. This information is particularly interesting as the researchers could learn more about the role of the immune system in asthma, although they cannot rule out the possibility that sialostatin might eventually be adapted for use as a medicine in humans.