Fleas

[Angelica365]

Can they catch fleas and get infested.

 

[Reenie]

I think I've read that there isn't a species specific flea, but cat or dog fleas can bite them the same way they can us. They can get mites though, or fly strike, and other skin conditions such as ringworm, which is a fungus rather than a parasite.

 

[Wiebke]

Can they catch fleas and get infested.

Hi! No, guinea pigs don't have species specific fleas. Fleas from other pets can shortly affect them (like they can humans), but cannot generally survive on them; that is why you don't catch anything from your guinea pigs apart from a short irritation at the very worst (I've had piggies for nearly three decades of my life and it's never happened to me). Please NEVER use any pet shop flea powders on guinea pigs; they can be lethal for them as they contain substances that are poisonous for small animals!
Fleas And Flea Powders

Here is a list of parasites that guinea pigs can get, mainly invisible mange mites that lay their eggs into the skin, which becomes very painful and inflamed (which require treating with a good quality ivermectin or selamectin product); hay or fur mites (which come with hay and fix their tiny egg cases to the hairs, usually at the bum end) and lice, which are small pale moving things. Please do not treat on spec and do not treat with low dosed broad spectrum shop products that do more harm and cause more suffering (up to death) as they will not cut through an acute outbreak - and that will be more expensive in the end than seeing a vet and getting proper care in the first case!
There are a couple of other parasites that guinea pigs can catch from other pet species in your household, but with good care transmission is rare and usually not an issue; and they won't be an issue if you only have got guinea pigs.
Guinea Lynx :: Parasites
You have to also be aware that fungal skin infections can look very similar to a mange mite outbreak in the early stages, much more than textbook images will let you think. Fungal requires completely different treatment. The most aggressive form of it, ringworm, is also the most transmittable (including humans - hygiene is absolutely paramount if you deal with ringworm).
Ringworm is unfortunately rather common in shop bought young guinea pigs who have not yet got a fully working immune system when they are ripped away from their mums, shipped to pet stores and then thrust into homes as pets with no previous friendly human interactions. Exposure usually happens at the shop (ringworm spores are very difficult to get rid of), so you can reclaim any vet cost from the store if the outbreak happens within the first two weeks after the sale. Ringworm: Hygiene And Pictures

The other issue that you need to keep an eye out with any bought guinea pigs is respiratory infections. Crackly breathing and gunky eyes are usually the most visible signs at the sale; loss of appetite and apathy are less obvious. See a vet asap if your new guinea pigs develop any symptoms; URI can and does kill if you wait too long. By the time your piggy is apathetic, it is already likely too late. A pet shop should refund the vet cost in the first couple of weeks after sale, you need to have the money ready upfront for treatment in the US. Please make sure that you have got that before you get any pets!
Again, URI is an opportunistic illness that is easily spread in a shop with a number of stressed youngsters in close proximity.
Guinea Lynx :: URI

Fly strike (flesh eating maggots that are laid by some flies) are very rare in indoors piggies, but it can happen, especially in more rural areas. Fly strike is a life and death emergency that needs to be seen at any time of the day or night; if it happens, it generally affects older piggies with limited mobility that are no longer able to clean their own genitalia. Healthy guinea pigs are not at risk.

There are unfortunately no recommended vets listed for your state.
Guinea Lynx :: GL's Vet List

I hope that this helps you?