The design of this study was composed of three parts: 1) collection of cases and strain genes of
Fonsecaea
spp. in China and abroad; 2) an exploration of the
origin and transmission pathways of pathogenic
Fonsecaea
spp. strains collected in the laboratory; and 3) the temporal phylogenetic tree and haplotype
network validation. The systematic review part strictly followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.
The research plan was reviewed and approved by the National Health Service (NHS), and assigned the PROSPERO registration number: CRD42021275308.
Search strategy and inclusion criteria
Literature reviews included the selection of all articles addressing worldwide epidemiology of chromoblastomycosis that were published in different
languages (including Chinese, English, French, Japanese, and Spanish) between 2000 and 2021. Searching work done from PubMed and the Chinese-
language CNKI, SinoMed, and Wanfang databases. The search terms were (fungi[MeSH Terms]) AND ((“
Fonsecaea
”) OR (“
monophora
”) OR (“
pedrosoi
”) OR
(“
multimorphosa
”) OR (“
nubica
”) OR (“
erecta
”) OR (“
brasiliensis
”) OR (“
minima
”) OR (“
compacta
”) OR (“
pugnacius
”) OR (“
Trichosporum pedrosianum
”) OR
(“
Trichosporum pedrosoi
”) OR (“
Hormodendrum pedrosoi
”) OR (“
Hormodendroides pedrosoi
”) OR (“
Rhinocladiella pedrosoi
”) OR (“
Phialophora pedrosoi
”) OR
(“
Gomphinaria pedrosoi
”) OR (“
Carrionia pedrosoi
”) OR (“
Acrotheca pedrosoi
”)) OR ((“Medlar body”) OR (“Medlar bodies”) OR (“sclerotic bodies”)) AND
((Chromoblastomycoses) or (Chromomycos*s) or (“Dermatitis Verrucosa”)). All studies in this thorough evaluation met the major CBM diagnostic criteria: 1) A
direct observation with 10% Potassium hydroxide revealed the presence of dark-colored, thick-walled muriform cells in a biological sample; and 2) fungal
isolation was performed on Sabouraud dextrose agar, and
Fonsecaea spp
. was discovered using molecular analysis of strains taken from patients. Cultivation
and DNA sequencing from culture veried the identity (Campos-Macias et al., 2021).
Fungal strains
All strains were kept in the CBS culture collection (https://wi.knaw.nl/) and PubMed’s (https://www.ncbi.nlm.nih.gov/) reference collection under the name
'
Fonsecaea
'. All type strains that were available were included. Data on
Fonsecaea
spp. used in this investigation were obtained from GenBank
(https://www.ncbi.nlm.nih.gov/); the accession numbers of the sequences utilized are presented in Supplementary Table1. Cultures originated from the
Centraalbureau voor Schimmelcultures (CBS-KNAW Fungal Biodiversity Centre, Utrecht, The Netherlands, https://www.gbif.org/dataset/82dc5194-f762-11e1-
a439-00145eb45e9a). Stock cultures were maintained on slants of Sabouraud’s dextrose agar and Potato dextrose agar at 35°C. Strains are listed in
Supplementary Table1.
Genetic data analysis, dated phylogeny, and statistical analysis of collected strains
Genetic data analysis, dated phylogeny, and statistical analysis of the collected strains ribosomal internal transcribed spacer (ITS) sequences were collected
using MEGA v. 11 ((Kumar et al., 2018)), Sequence were aligned using the ClustalW option and a neighbor-joining tree was estimated using the Kimura 2-
parameter model plus gamma correction (K2 + G: 0.96), with 500 bootstrap replications. All temporal phylogenetic trees were built using the RelTime-ML
method in MEGA v. 11 (Mello, 2018). Divergence times for
Cryptococcus gattii
,
Candida albicans
,
Aspergillus fumigatus
, and
Pyrenula anomala
are referenced
on the website (http://www.timetree.org /search/goto_pairwise), and the searched divergence times were used as calibration time points for the molecular
clock to infer evolutionary times. DnaSP v.6 (Rozas et al., 2017) on the Universitat de Barcelona server (http://www.ub.edu/dnasp/) was used to determine the
extent of DNA polymorphism. All haplotype network models were constructed using PopART 1.7 (http://popart.otago.ac.nz/index.shtml; Clement et al., 2000).
Categorical variables were compared with chi-square tests. Differences between groups were considered statistically signicant if P-values were ≤ 0.05.
Divergence times are reported in millions of years ago (Ma).
Results
Information on the characteristics of the collected global cases and strains
The study included a total of 498 CBM cases that were published. The worldwide distribution and prevalence of CBM cases are shown respectively in Fig.1,
while the main characteristics of CBM are illustrated by countries and continents as summarized in Supplementary Table1. A total of 510
Fonsecaea
spp.
were evaluated, of which 44 were environmental plant, and four were animal. Data obtained on geographic origins and sources of isolation are listed in
Supplementary Table2. Regions with a high incidence of cases include Brazil, Venezuela, and Colombia (South America); Mexico, Cuba, and the United States
(North America); China, India, Vietnam, and Japan (Asia); Madagascar (Africa); and France and the Netherlands (Europe). We compared the number of
isolated
Fonsecaea
spp. strains with the number of reported cases of
chromoblastomycosis caused by this fungus in the same time period, showing the same trend. From 2000 to the rst half of 2021, the number of reported
cases and strains of
Fonsecaea
spp. infections were increased progressively, and both showed a consistent trend.
In each 4-year period, we found that the number of cases of the four pathogenic species increased over time, with the most pronounced increases in
F.
pedrosoi
and
F. monophora
.
Fonsecaea pedrosoi and F. monophora
had the highest number of cases and isolated strains among patients.