Cryptococcus and cryptococcosis in Iran during 1969-2019: A systematic review and meta-analysis

OBJECTIVE

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Wading bird guano enrichment of soil nutrients in tree islands of the Florida Everglades

Differential distribution of nutrients within an ecosystem can offer insight of ecological and physical processes that are otherwise unclear. This study was conducted to determine if enrichment of phosphorus (P) in tree island soils of the Florida Everglades can be explained by bird guano deposition. Concentrations of total carbon, nitrogen (N), and P, and N stable isotope ratio (δ(15)N) were determined on soil samples from 46 tree islands. Total elemental concentrations and δ(15)N were determined on wading bird guano. Sequential chemical extraction of P pools was also performed on guano. Guano contained between 53.1 and 123.7 g-N kg(-1) and 20.7 and 56.7 g-P kg(-1). Most of the P present in guano was extractable by HCl, which ranged from 82 to 97% of the total P. Total P of tree islands classified as having low or high P soils averaged 0.71 and 40.6 g kg(-1), respectively. Tree island soil with high total P concentration was found to have a similar δ(15)N signature and total P concentration as bird guano. Phosphorus concentrations and δ(15)N were positively correlated in tree island soils (r = 0.83, p< 0.0001). Potential input of guano with elevated concentrations of N and P, and (15)N enriched N, relative to other sources suggests that guano deposition in tree island soils is a mechanism contributing to this pattern.