Paracoccidioidomycosis Diagnosed in Europe—A Systematic Literature Review

Paracoccidioidomycosis is a systemic mycosis that is endemic in geographical regions of Central and South America. Cases that occur in nonendemic regions of the world are imported through migration and travel. Due to the limited number of cases in Europe, most physicians are not familiar with paracoccidioidomycosis and its close clinical and histopathological resemblance to other infectious and noninfectious disease. To increase awareness of this insidious mycosis, we conducted a systematic review to summarize the evidence on cases diagnosed and reported in Europe. We searched PubMed and Embase to identify cases of paracoccidioidomycosis diagnosed in European countries. In addition, we used Scopus for citation tracking and manually screened bibliographies of relevant articles. We conducted dual abstract and full-text screening of references yielded by our searches. To identify publications published prior to 1985, we used the previously published review by Ajello et al. Overall, we identified 83 cases of paracoccidioidomycosis diagnosed in 11 European countries, published in 68 articles. Age of patients ranged from 24 to 77 years; the majority were male. Time from leaving the endemic region and first occurrence of symptoms considerably varied. Our review illustrates the challenges of considering systemic mycosis in the differential diagnosis of people returning or immigrating to Europe from endemic areas. Travel history is important for diagnostic-workup, though it might be difficult to obtain due to possible long latency period of the disease.


Introduction
Paracoccidioidomycosis, also known as South American blastomycosis, is a systemic fungal infection [1] caused by the thermally dimorphic fungi of the species Paracoccidioides brasiliensis and the related species P. americana, P. restrepiensis, P. venezuelensis, and P. lutzii [2,3]. These fungi are endemic to certain geographic regions of Central and South America [4]. Most of the cases of paracoccidioidomycosis are reported in Brazil, followed by Colombia, Venezuela, Ecuador, and Argentina [5]. Based on estimates from epidemiological data, the number of cases of paracoccidioidomycosis in Brazil ranges from 3360 to 5600 per year [5]. The incidence of cases considerably varies among regions with low, moderate or high endemicity [5]. According to estimates, in regions with a stable endemic situation, the annual incidence of paracoccidioidomycosis ranges from 1 to 4 cases per 100,000 inhabitants [5].
People living in rural areas and working in agriculture are particularly at risk for this mycosis [1]. The risk of infection is higher for men than women [6]. The chronic form (adult type) accounts for the majority of cases [4]. This form of paracoccidioidomycosis is progressive over months or years and can be unifocal, if only one site is affected, or multifocal, in case of dissemination [7]. The organ most frequently affected is the lung [7]. Skin, oral mucosa, pharynx, larynx, lymph nodes, adrenal glands, central nervous system, bones, or joints may also be affected [8]. Symptoms of the disease can be systemic (e.g., weight loss, general weakness) or related to specific organ affection (e.g., cough, shortness of breath) [8]. In particular, pulmonary affection, lymphadenopathy, and B symptoms often lead to clinical signs similar to tuberculosis [8,9].
Paracoccidioidomycosis differential diagnosis is particularly challenging, because clinical signs and symptoms, as well as histopathological findings, resemble numerous other infections (e.g., tuberculosis) and noninfectious diseases (e.g., sarcoidosis) [8]. In addition, a long latency period [7] between exposure and manifestation of symptoms, as well as limited clinical experience, make adequate diagnosis difficult. In nonendemic areas, the history of travel and residency in endemic regions is a key to consider paracoccidioidomycosis for differential diagnosis.
Most physicians in nonendemic areas are unfamiliar with the clinical picture of endemic systemic mycoses because they are rarely presented to them. This in turn increases the risk that patients with paracoccidioidomycosis end up with misdiagnosis or remain undiagnosed. Subsequently, this results in no or inappropriate therapy. Therefore, it is important to provide information about the disease presentations in nonendemic regions.
A previously published review by Ajello et al. 1985 [10] comprehensively summarized internationally published cases of paracoccidioidomycosis from Africa, Asia, the Middle East, North America, and Europe [10]. However, this review is now 35 years old and needs to be updated.
The purpose of this systematic review is to summarize the evidence of paracoccidioidomycosis imported to nonendemic European countries. Thereby, we aim to increase awareness for this fungal infection and provide important information regarding its challenging diagnosis.

Materials and Methods
For reporting of this systematic review, we followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement (PRISMA) [11].

Information Sources and Literature Search
An experienced information specialist searched PubMed and Embase (Embase.com (accessed on 16 December 2020)) from inception to June 15 and 16, 2020 to identify relevant publications. We used a combination of subject headings and title and abstract free-text terms. We restricted our search to adults and humans. We have provided the detailed search strategy in Appendix A (Tables A1 and A2). In addition to database searches, we used Scopus (Elsevier) on 16 June 2020 to perform forward and backward citation tracking of included publications and reviews. We also manually screened reference lists of these records, in case the reference lists available via Scopus were incomplete. To identify publications published prior to 1985, we used the previous review published by Ajello et al. [10]. We used references found by our search to identify relevant publications published in 1985 or later.

Eligibility Criteria and Study Selection
Our population of interest was adults of any age and origin diagnosed with paracoccidioidomycosis (South American blastomycosis) in geographic Europe. We considered any case description of an acute or chronic form of paracoccidioidomycosis as eligible for this review if authors provided sufficient clinical information on number of cases, country of exposure, and diagnosis. Publications were included regardless of language and type of publication. We included case series and case reports, observational studies, reviews providing information mentioned above and published as abstracts, full-articles, letters, and editorials. Table 1 provides a summary of eligibility criteria. After a pilot round, two reviewers independently screened each title and abstract. Eligible publications subsequently underwent independent dual full-text assessment. We solved disagreements by consensus or involvement of a senior reviewer. Throughout the whole study selection process, we used the web-based software Covidence [12]. We organized search and screening results in an EndNote ® X9 bibliographic database (Clarivate, PA, USA).

Data Collection Process and Evidence Synthesis
We extracted the following relevant information from each article into pilot-tested evidence tables: author, year, study design, language, country of diagnosis, country of exposure, number of cases, patient characteristics (age, gender, occupation, affected organ(s), systemic antimycotic therapy, and treatment response), and latency period. If the publication language was not English, we asked native speakers to translate or used the online tool DeepL (http://www.deepl.com (accessed on 15 January 2021)) for translations into German. We synthesized data of identified articles narratively.

Clinical Patient Characteristics
The age of the patients ranged from 24 to 77 years. The infection mainly affected men. In most cases, exposure to Paracoccidioides took place in Venezuela, followed by Brazil and Ecuador. The most common occupations were field and construction workers. Latency period, defined as the period from leaving the endemic region until occurrence of first symptoms or medical contact, ranged from six days to 50 years. Table 3 shows patient  Table 2 summarizes the number of publications and reported cases by country. Spain reported most of the cases, followed by Italy and Germany. The majority of articles were written in English or Spanish. Other publication languages were German, Portuguese, Italian, Norwegian and French.

Clinical Patient Characteristics
The age of the patients ranged from 24 to 77 years. The infection mainly affected men. In most cases, exposure to Paracoccidioides took place in Venezuela, followed by Brazil and Ecuador. The most common occupations were field and construction workers. Latency period, defined as the period from leaving the endemic region until occurrence of first symptoms or medical contact, ranged from six days to 50 years. Table 3 shows patient characteristics, country of exposure, latency period, affected organ(s), systemic antimycotic therapy and response to treatment grouped by countries in which the diagnosis was made.

Differential Diagnosis
Table A3 of Appendix A shows infectious and non-infectious diseases that were considered for differential diagnosis of cases in the included articles.

Diagnostic Work-up
The diagnostic workup varied across publications. Usually, Paracoccidioides spp. was identified from clinical specimens through microscopic visualization and/or culture. In addition, some of the authors reported results from serological tests and/or molecular biological techniques such as polymerase chain reaction (PCR). Table A3 provides information on diagnostic workup in individual cases of paracoccidioidomycosis.
In general, direct examination, using 10% potassium hydroxide applied to different samples, is effective and inexpensive. A histologic examination of tissue specimens using silver methenamine or periodic acid-Schiff stain is common and practical when patients present with oral or other skin lesions. In a clinical sample, Paracoccidioides spp. appear as globose yeast cells with multiple buds and a thick refractile wall [81].

Discussion
Our systematic review summarizes the evidence on published case reports of imported paracoccidioidomycosis diagnosed in Europe. To the best of our knowledge, this is the most recent and comprehensive review of published cases of this systematic mycosis endemic to geographical regions of Central and South America. While narrative reviews on patients with this disease often included a nonsystematic search, we followed a systematic approach with a much broader scope to identify all published cases of paracoccidioidomycosis imported to Europe. In addition, the last systematic assessment of case reports on paracoccidioidomycosis was published in 1985, almost four decades ago [10]. A more recent narrative review focused only on cases diagnosed in Spain [82].
Our systematic review of case reports and case series emphasizes the clinical challenges and pitfalls of paracoccidioidomycosis. Most of the physicians in non-endemic regions such as Europe are unfamiliar with systemic mycosis. They struggle with the diagnostic work-up and management due to several reasons. In general, depending on the type, clinical presentation of patients with paracoccidioidomycosis is variable [4]. A major issue is the clinical similarity to several other infectious and non-infectious diseases [81]. Paracoccidioidomycosis is commonly misdiagnosed as tuberculosis [83]. The clinical picture of tuberculosis resembles the chronic progressive form of paracoccidioidomycosis [9]. The differential diagnosis of chronic paracoccidioidomycosis with lung involvement also includes coccidioidomycosis, histoplasmosis, sarcoidosis, pneumoconiosis, interstitial pneumonia, and malignancy [84]. Inappropriate treatment could have harmful consequences for the patient, without any prognostic impact on systemic mycosis. In addition, the latency period from pathogen exposure to development of symptoms is highly variable and might comprise several decades when patients might already have left the endemic region [7]. Therefore, clinicians must inquire about any short-and long-term stay (travel and residency) in endemic areas and even time abroad many years preceding presentation. Figure 2 summarizes important aspects that have to be considered for diagnosis of paracoccidioidomycosis, including signs and symptoms, travel history, and imaging.
If paracoccidioidomycosis is considered for differential diagnosis, clinicians should provide this information to the microbiologist, pathologist and other laboratory personnel to ensure that adequate methods for direct and indirect identification of the pathogen are applied. In addition, laboratory personnel need to apply safety precautions when collected specimens are handled.
The strengths of our work are the systematic literature search and screening. However, this systematic review has several limitations. First, we have not included cases that may have been diagnosed but never published. Second, because translation methods varied, we might have missed relevant information in the articles. A native speaker translated Spanish texts into German but online electronic translation tools provided translations for all other languages (11 publications) except texts published in English and German. Third, our findings rely on not uniformly structured case reports and cases series that are considered as low-level evidence. Finally, although we conducted comprehensive additional literature searches, we might have missed studies not cited in previous reviews and not indexed in electronic databases due to very early publication dates or non-indexed journals. If paracoccidioidomycosis is considered for differential diagnosis, clinicians should provide this information to the microbiologist, pathologist and other laboratory personnel to ensure that adequate methods for direct and indirect identification of the pathogen are applied. In addition, laboratory personnel need to apply safety precautions when collected specimens are handled.
The strengths of our work are the systematic literature search and screening. However, this systematic review has several limitations. First, we have not included cases that may have been diagnosed but never published. Second, because translation methods varied, we might have missed relevant information in the articles. A native speaker translated Spanish texts into German but online electronic translation tools provided translations for all other languages (11 publications) except texts published in English and German. Third, our findings rely on not uniformly structured case reports and cases series that are considered as low-level evidence. Finally, although we conducted comprehensive additional literature searches, we might have missed studies not cited in previous reviews and not indexed in electronic databases due to very early publication dates or non-indexed journals.

Conclusions
In conclusion, this review highlights the importance of considering systemic mycosis in the differential diagnosis of people with symptoms of tuberculosis who have either returned to Europe from endemic areas or were natives of endemic countries who immigrated to Europe. In light of systemic mycosis's potentially long latency period, extensive evaluation of travel history is an essential key for a quick and correct diagnosis of systematic endemic mycosis such as paracoccidioidomycosis.

Conclusions
In conclusion, this review highlights the importance of considering systemic mycosis in the differential diagnosis of people with symptoms of tuberculosis who have either returned to Europe from endemic areas or were natives of endemic countries who immigrated to Europe. In light of systemic mycosis's potentially long latency period, extensive evaluation of travel history is an essential key for a quick and correct diagnosis of systematic endemic mycosis such as paracoccidioidomycosis.

Data Availability Statement:
No new data were created or analyzed in this study. Data sharing is not applicable to this article.

Acknowledgments:
We would like to thank Edith Kertesz from Danube University for administrative support.

Conflicts of Interest:
The authors declare no conflict of interest.    [85].