Mites That Bite Humans: Bird and Rodent Mites
If you are experiencing crawling, biting or itching sensations caused by something you cannot see, chances are it's a mite. There are several mite species that can cause these sensations, only one of which is actually capable of living and reproducing on humans. Due to this unique attribute, Sarcoptes scabiei , variety hominis (commonly referred to as 'scabies') is discussed in two separate articles entitled 'Atypical Scabies Symptoms' and 'How Do You Know If Your Scabies Treatment Worked: Post Scabies Syndrome.' Here I will instead focus on several additional mite species that cannot live off of humans but can nevertheless cause long-lasting discomfort if not managed properly.
In order to determine the cause of your crawling, biting or itching sensations, it will be helpful to list all potential culprits, and rule them out one by one. First, many people experiencing a mite infestation report the biting is worse at nighttime, and in certain places such as the bedroom or near the computer. This scenario could actually indicate you have bedbugs. Bedbugs are not mites, they are much larger (adults are about the size of a fingernail) and can be easily seen with the naked eye if one looks in the right places, i.e., in mattress seams or other cracks and crevices around the bedroom. Once this possibility is ruled out, one should be sure there is no pet in the house that has severe dandruff or mange. This is often an indication the pet has a mite infestation. The mites that affect your pets are typically host specific, meaning they can only live and reproduce on one particular type of animal, such as a dog. An example of such a mite is Sarcoptes scabiei , variety canis. This mite cannot live or reproduce on you, but so long as your dog is available for these purposes, the population will continue to thrive and inadvertently bite you. As such, treating yourself will do no good. You will simply continue to be bitten until you treat your pet for the infestation. If you have multiple pets, it is necessary to treat all of them at the same time and to launder any bedding items or play toys potentially harboring mites.
Once these (relatively) obvious culprits are ruled out, it is necessary to consider bird and/or rodent mites. There are several species of bird and rodent mites known to bite humans, although none of them can actually live or reproduce by doing so. Bird mites that bite humans include the chicken mite (Dermanyssus gallinae) and the Northern fowl mite (Ornithonyssus sylviarum). Rodent mites that bite humans include the house mouse mite (Liponyssoides saguineus), the tropical rat mite (Ornithonyssus bacoti) and the spiny rat mite (Laelaps echidnina). Bird and rodent mites typically live in the nest of their host until a) the host is no longer enough to support the number of mites living there, b) the host leaves the nest, or c) the host dies. In any of these cases, the remaining mites are forced to leave the nest to search for a new host. In doing so, they often make their way into nearby buildings and begin to bite humans, which they find by using their CO2, heat and possibly moisture sensors.
When trying to determine if one has a bird or rodent mite infestation, It is helpful to first conduct a search around the outside of the house for any bird nests that might be located under the eves, in the gutters, or perhaps on tree branches that touch the house. Check all attic and crawl spaces as well as under porches and decks or anywhere else a rodent or bird could be nesting. If you find anything, you can use this information to lead you to possible entry points through which the mites might be entering the house. Check doorways, window sills, electrical outlets, air vents and possibly even drains. You may even find mites in your bed, if they have made it that far, which is quite possible if they are coming from a nest, say, just outside your bedroom window. You will not be able to distinguish between the various bird and rodent mite species without a microscope, as it literally comes down to how many hairs each has on particular pairs of legs. However upon first glance, all of these mite species will look like dust specs that can appear red, brown or black if they have recently eaten a blood meal, or more of a translucent whitish gray if they have not eaten for a while. If you stare at them for a minute or so, you will notice that the 'dust' is crawling.
If you do indeed find bird or rodent mites, it will be necessary to first remove the animal(s) and the nest(s) (be sure to be thorough because there are often multiple nests) and to then seal up any entry points through which the animals were able to gain access to the house. It may be necessary to cut back tree branches that touch or overhang the house in order to prevent the same animals from returning, or more animals from coming. After doing this, it may further be necessary to fumigate, as these mite populations could feasibly have multiplied into the tens of thousands and some of these species can live for close to an entire year without a meal from the proper host. This means that although they cannot live off of your blood, they can sure continue to try for a very very long and uncomfortable time. Remember, fumigation typically has to occur twice, about a week apart, in order to break the egg cycle, since no available pesticides are known to kill eggs. It may even be necessary to do more than one round of fumigation because bird and rodent mites are notorious for hiding in places that are difficult to reach with pesticides.
If you are still unable to determine the source of your crawling, biting or itching sensations, I would next suggest considering scabies. Not dog or cat scabies, but human scabies, which you cannot see with the naked eye. A dermatologist should be able to either recognize typical symptoms or take a skin scraping in order to identify a mite, its eggs or feces under a microscope. If they still cannot say for certain, I would suggest asking the doctor to prescribe treatment for scabies anyway because it is often very difficult to diagnose. If you have come to this, please read the following articles: