Eye Infections - Fungal & Parasitic
Below are some excerpts from a long publication on eye fungal and parasitic infections.
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=88956
ABSTRACT
The unique structure of the human eye as well as exposure of the eye directly to the environment renders it vulnerable to a number of uncommon infectious diseases caused by fungi and parasites. Host defenses directed against these microorganisms, once anatomical barriers are breached, are often insufficient to prevent loss of vision. Therefore, the timely identification and treatment of the involved microorganisms are paramount. The anatomy of the eye and its surrounding structures is presented with an emphasis upon the association of the anatomy with specific infection of fungi and parasites. For example, filamentous fungal infections of the eye are usually due to penetrating trauma by objects contaminated by vegetable matter of the cornea or globe or, by extension, of infection from adjacent paranasal sinuses. Fungal endophthalmitis and chorioretinitis, on the other hand, are usually the result of antecedent fungemia seeding the ocular tissue. Candida spp. are the most common cause of endogenous endophthalmitis, although initial infection with the dimorphic fungi may lead to infection and scarring of the chorioretina. Contact lens wear is associated with keratitis caused by yeasts, filamentous fungi, and Acanthamoebae spp. Most parasitic infections of the eye, however, arise following bloodborne carriage of the microorganism to the eye or adjacent structures.
FUNGAL INFECTIONS OF THE EYE
Epidemiology of Fungal Eye Infections
Ophthalmologists and optometrists, in particular, and clinicians, in general, must be knowledgeable of the pathogenesis of fungal eye infections. Mycotic eye infections are commonplace. For example, the yeast Candida albicans is the most common cause of endogenous endophthalmitis. Filamentous fungi, such as Fusarium solani and Aspergillus flavus, may constitute up to one-third of all cases of traumatic infectious keratitis (157). Furthermore, patients with AIDS may contract many different fungal infections of the eye and adjacent structures (Table 2).
PARASITIC INFECTIONS OF THE EYE
While relatively uncommon in the United States, various parasitic infections are important causes of ophthalmic disease worldwide. For example, toxoplasmosis and onchocerciasis affect millions of persons, with a significant proportion manifesting ocular involvement. As with fungal infections, the epidemiology of parasitic ocular disease also reflects the habitats of causative parasites as well as the habits and health status of the patient. Additionally, congenital infections may pose diagnostic and treatment challenges. The classes of infection are varied and include protozoa, nematodes, cestodes, trematodes, and ectoparasites. Like fungal endophthalmitis, the geographic location is an important determining factor in the development of parasitic infections. Additional considerations must include local sanitation and the presence of a vector for transmission as well as the more-complicated life cycles of the parasites and definitive hosts. Because of this somewhat more complex scenario, as well as the tendency for the parasites to cause a wider variety of pathologic lesions, the various parasitic etiologies of ocular disease will be addressed individually, including epidemiology, pathogenesis, diagnosis, and treatment.