Nose and eyes are not the preferred sites for the majority of parasites. However, even though it is less frequent than for some other sites, such as the intestines for example, a few types of parasites are able to infect the nose or the eyes. The next paragraphs will present the main ones.
Some species of Acanthameoba are responsible for the Acanthamoeba keratitis, a rare but severe infection of the eye. This parasite affects the cornea and it has to be treated quickly, as it is susceptible to lead to visual impairment, or even blindness. However, the treatment of this infection is a little bit tricky explaining why it is preferable to initiate the treatment at an early stage of the infection in order to increase the chance of preserving the vision. It is interesting to note that in some cases (but not all), the visual impairment or blindness can be reversed by a corneal transplant. Acanthamoeba keratitis affects usually otherwise healthy people and is prevalent in developed countries, as it is mainly transmitted by improper use and washing of contact lenses. However, in developing countries, cases not related to contact lenses are also observed, as this parasite is one of the most frequently found protozoan parasites in soil and untreated water.
The filarial nematode Onchocerca volvulus infects also the eyes. This parasite is responsible for a disease called onchocerciasis, occurring mostly in sub-Saharan Africa. The common name for this disease is «river blindness». Actually, the main symptom of this parasitic disease is a long-term inflammation of the cornea, commonly known as keratitis. In the long term, it will cause a progressive thickening of the cornea, which will eventually leads to blindness. Apart form the eyes, this parasite is also known to affect the skin. It is interesting to note that this parasite is the second most common infectious causes of blindness, after the infection with the bacterium Chlamydia trachomatis.
Another filarial nematode is also able to infect the eyes. Its name is Loa loa and it causes a disease called loiasis. This disease occurs exclusively in Africa and India and is commonly called the «eye worm» or the «African eye worm». These worms are usually present in subcutaneous tissues, but it is possible that a worm migrates to the eye where it causes swelling. It is relatively easy to surgically remove the worm from the eye in order to decrease the associated pain. However, the different forms of the worm will still be present elsewhere in the body and must be treated in order to prevent the reoccurrence of other eye worms. Treatment of loiasis is very tricky, as the different treatments available have potential life-threatening side effects.
Depending on the species involved, the parasite Leishmania is susceptible to cause three forms of infection. One of them is called mucocutaneous leishmaniasis. This disease involves the progressive degradation of the mucosa of the mouth, the nose and the throat cavities. Unfortunately, this disease can lead to debilitating scars in the face if it is not treated rapidly. Furthermore, in rare cases, it can be life-threatening if the mucosa of the throat is too much damage and if it impairs the breathing.
Finally, it is not excluded that some other parasites might migrate occasionally to the eyes or the nose. However, these parasites are generally located elsewhere in the body and migrates to these parts only in rare circumstances, mainly in the case of massive infestation. Furthermore, without really infecting it, some parasites can try to go out of the body through the nose in case of massive infestation. It is the case for example of the roundworm Ascaris lumbricoides that is occasionally able to go out of the body through the nose or the mouth, as well as in the stool (link to Can you poop out a parasites).
Source: Centers for Disease Control and Prevention
