I had a possum for a pet.
A fairly large animal, I picked her up outside, maybe to get her out of the rain. When I grabbed her she tensed up a bit as if to claw me, and turned her head ’round with threat to bite, but soft words and good intentions calmed her down. I took her inside a nearby house where a small party was going on. The partygoers said that my dog was strange looking. I didn’t contradict them, and they seemed satisfied, so I put the possum down to roam. More importantly, the owner of the house had a little dark dachshund that was running about and when it came close to my possum, all the dog’s hair– which up ’til this point had appeared classically short –stood on end like a startled cat’s. At this point it occurred to me, both for mine and the dachshund’s sake (but not for the partiers), that I should be worried about getting fleas from my possum. I started to itch.
Then I woke up.
Tome of Goatllama 
Thank you for sharing because I think your dream was meant to be a wake-up call for me. I started looking up possums and their parasites and diseases. I didn’t realize that I should definitely be keeping them out of the porch due to fleas but also due to this:
Tularemia is a rare infectious disease. Also known as rabbit fever or deer fly fever, it typically attacks the skin, eyes, lymph nodes and lungs. Tularemia is caused by the bacterium Francisella tularensis. The disease mainly affects rabbits, hares, and rodents, such as muskrats and squirrels.
I read that possums often carry this, and of course my possum could be leaving the bacteria on the porch floor or the water dishes, etc. I don’t let F & F eat out of the bowl a possum has eaten out of but I don’t always know if they do it in the middle of the night, and I don’t always know if the possum has had some of their water. This also leaves Bor, Jane & River susceptible because they go out on the porch and the floor…ugh. Time to totally disinfect the back porch, which I was planning to do this weekend anyway, but now…good grief!!
And I read possums definitely have fleas. Fergus got Bravecto when he recently went to the vet, and Finn just got Frontline a week or so ago. This morning, I have now treated all the indoor cats. Boris is really pissed at me as usual. Here is some more about possums. I love them, but they are going to have to stay out!
Most people can point to an opossum in a lineup of wildlife creatures. Its white face and pointy rat-like nose and tail are easily recognizable. But most people really don’t know all that much about these critters. And, if you’ve been seeing opossums on your property, it is probably a good idea for you to take some time to get to know them. It might just save you from having an unfortunate incident. Here are five things you may not know about opossums, and a few things you really should know.
Opossums are:
not possums. Yup. It is a common mistake. The possum is actually a tree-climbing marsupial that lives in Australia, and a distant cousin to the North American, opossum. not a rodent. Like its cousin the possum, the opossum is a marsupial, which is to say that it is an animal that has a pouch. It uses this pouch to carry its young around. Other marsupials you may be familiar with are koalas and kangaroos. the only pouched mammal in the U.S. and Canada. blessed to have two big toes that act like opposable thumbs. These digits, called halux, help the opossums climb trees with ease. They have this anatomical feature in common with monkeys and other primates. immune to a lot of stuff. These critters have such a good immune system, they are hardly ever found with the rabies virus, and they are not considered reservoirs for Lyme disease. While these furry creatures can be quite interesting, they can also create many problems when they come onto our property. One of the most prominent problems they cause is lawn damage. Opossums are fond of grubs. When they come into a yard, they will damage turf grass as they dig to get at the grubs under the surface. But, arguably, those grubs would have done some damage anyway.
If an opossum makes its home under a porch, deck, shed, or outbuilding, it may present a danger to pets and children. While not an aggressive animal, by any means, it will defend itself if cornered or protecting young. Most of the time, it will open its mouth wide and bare its teeth as a threatening posture, or simply play dead.
The real risk of opossums is in the introduction of parasites such as fleas and lice, especially to domesticated cats. Outdoor cats are curious and are prone to go into areas where opossums have been. When they do, they can pick these parasites up and bring them into the house. It is important to note, however, that opossums are incredible groomers and this drive for constant grooming perfection makes them a rare carrier of ticks. In fact, they eat and digest most of the ticks that are unfortunate enough to get on them.
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Wow. Yeah, definitely sounds like it would be better to play it safer in spite of how cute (and largely harmless) the creatures are.