Limited data are available on the epidemiology and etiology of cryptococcal infections in the Middle East. We aimed to conduct the systematic review and meta-analysis to summarize the epidemiological data on prevalence of Cryptococcus species complexes in trees and their surroundings, bird guano and secretions, animals, and highlight the reported episodes of cryptococcosis in Iran.

Twelve databases, including PubMed, Science Direct, Scopus, Proquest, Google Scholar, Embase, and the ISI Web of Science, as well as the national databases, from January 1969 to October 2019 were searched. Furthermore, gray literature (e.g., thesis, congress abstracts) was evaluated using Iran Doc and www.thesis.research.ac.ir/. Search process was accomplished on English or Persian language articles using the following keywords: “Cryptococcus”, “Cryptococcosis”, “invasive fungal infection”, “Humans”, “Birds”, “Pigeon”, “Animals”, “Tree”, “Eucalyptus”, and “Iran”, both alone and in combination.

Overall 36 studies were eligible regarding Cryptococcus and cryptococcosis in Iran. The total prevalence rates of Cryptococcus species in the tree was 4.7% (95% CI: 2.3–7.8), and in bird guano was 20.4% (95% CI: 10.7–32.2). Cryptococcosis in animal, and human were 1.7% (95% CI: 0.01–5.1), and 2.8% (95% CI: 0.7v6.1), respectively. The highest prevalence of Cryptococcus in the trees (14.6%), and bird guano (89.4%) in Khorasan, animals (8.9%) in Chaharmahal and Bakhtiari, and human (4.4%) in Mazandaran provinces were reported.

Given the significant risk of Cryptococcus species for susceptible humans, mainly HIV-infected patients, it seems quite necessary to adopt concrete preventive strategies to pinpoint the environmental habitats of this yeast.