Monday, October 28, 2013

Cat and Mouse

A 30 year old G1P0 pregnant woman brings in her pet rat. "He's acting so weirdly," she says. Apparently, the rat "Ralph S Mouse" is normally terrified of cat urine. The woman owns a cat as well. However, lately, the mouse has been attracted to cat urine. His other fears of loud sounds, snakes, and strangers are not abolished.

Challenge: You tell the pregnant woman that she must not do what?

Image is in the public domain.


webhillizzy said...

The mouse isn't afraid of the cat any more, which suggests that the mouse is infected with toxoplasma gondii. I guess therefore you would tell her not to eat her pet mouse - but seriously, why would you have to tell her that? Or are you suggesting that possibly the mouse picked up toxo from the cat's litterbox and therefore you think the cat is shedding oocysts, and you should tell the woman not to clean the litterbox? Well, you might tell her just to make sure to clean it twice a day, because it takes time after the cat passes the oocysts for them to become infectious. But, i'm just not sure where you are going with this.

Craig Chen said...

yes - you're right. it's a really interestig PNAS article
Cat and Mouse

Toxoplasma gondii is an obligate intracellular parasite whose definitive host is the cat. However, it alters the behavior of intermediate hosts such as rats, described in the case. It can cause systemic infections in immunocompromised and pregnant patients. Thus, women who are pregnant are advised not to change cat litter (a source of infection). The image shows Toxoplasma tachyzoites.

Sources: UpToDate; Wikipedia; Vyas et. al “Behavioral changes induced by Toxoplasma infection of rodents are highly specific to aversion of cat odors.” in PNAS.