User:LaurenBiology/Granulomatous amoebic encephalitis

For my first edit of my Wikipedia article on Granulomatous Amoebic Encephalitis, I have decided to add an entirely new section on epidemiology. Furthermore, I have added 4 new references, 3 of which are peer reviewed academic journals and one is a parasitology textbook.

Epidemiology
GAE is more prevalent in immunocompromised individuals, however, there have been cases of immunocompetent people contracting this disease. Immunocompromised states that have been shown to increase an individual's risk of contracting GAE can include diabetes mellitus, organ transplant patients, AIDS, hematological malignancies, etc. Infection with one of the three causative genera of free-living amoeba can occur through environmental interactions with contaminated soil, air, or water. The first reported cases of an infection with a free living amoeba, such as the causative agents of GAE, were reported in Austria and the United States of America (Florida) in 1965. The large majority of cases with GAE have been recorded in developed countries as they have well-developed health care systems better suited for diagnosing and identifying these infections. All three genera, Acanthamoeba, Balamuthia, and Sappinia are capable of causing GAE however, infections with Acanthamoeba are by far the most prevalent followed by Balamuthia, and Sappinia respectively.

Acanthamoeba
Many of the genera responsible for causing GAE have a cosmopolitan distribution, specifically, infections with the Acanthamoeba genus have been seen to illustrate said geographical distribution. Cases of infection specifically with Acanthamoeba have recently been isolated from hot springs in Mexico, tap water in Latvia, municipal waters and soil samples from Iran, and in Malaysia Acanthamoeba specimens were found in dry samples of soil/ dust, moist samples of wet debris/ wet soil as well as water samples. The following global cases of GAE specifically caused by the genus Acanthamoeba have been recorded: USA (30), India (23), Austria (7), China (3), Turkey (2) Italy (3), Thailand (2), Japan (2), Spain (2), Germany (2), Taiwan (1), Sweden (1), Canada (1), Saudi Arabia (1), Mexico (1), Iran (1), and the UK (1). Since the recording of these estimates, it can be seen that infections with Acanthamoeba are common, with over 3000 individuals contracting keratitis, a disease specifically associated with contraction of Acanthamoeba in the eye region, and over 200 experiencing meningoencephalitis. Recognize that these cases illustrated on the global map only highlight those that have been diagnosed between the years 1990 and 2018. GAE is a commonly undiagnosed disease due to a wide variety of factors such as practitioner’s lack of familiarity with the symptoms associated with a free living amoebic infection or a lack of clinical resources to perform such a diagnosis. As a result, case estimates are conservative due to misdiagnosis, underreporting, and the fact that most diagnoses are done through autopsies where often these practices are not performed.

Balamuthia
Infection with this specific genus of free-living amoeba is rare in comparison to infection with the Acanthamoeba genus. This species of amoeba was once thought to be a nonpathogenic soil organism and as such exposure to soil can be seen as one of the direct routes for transmission of infections with this species. The first identified case of infection with Balamuthia mandrillaris was in 1986 when a post-mortem autopsy was performed on the brain of a baboon in a San Diego Zoo. Since its identification, Balamuthia mandrillaris has since been recognized for its pathogenic effects. Over 200 cases of infection with Balamuthia mandrillaris have been diagnosed since the original identification in 1986. Hispanics seem to be largely predisposed to infection with this specific genera of free living amoeba. There were over 109 cases of disease caused by Balamuthia mandrillaris in the United States between the years of 1974 and 2016. The median age of patients recorded was approximately 36 years old with over 50 percent of them being males.

Sappinia
Out of all the causative genera of GAE, infection with Sappinia is by far the most rare. Only one case of human infection with Sappinia has been identified to date. This case was isolated from a farmer from Texas who had previously been diagnosed with a sinus infection and was experiencing worsening neurological conditions. Contraction was thought to occur through inhalation of excrement from livestock which resulted in a variety of symptoms indicative of infection with GAE. After pathological review of an excised portion of the individuals left temporal lobe mass, they were later diagnosed with an infection with Sappinia diploidea. Presence of this free living amoeba was originally identified in the feces of various herbivores, however since cases are rare its pathogenic role is still being explored.