Introduction

Paracoccidioidomycosis (PCM) is a severe systemic mycosis, endemic in Latin America, mainly in Brazil. The infection typically occurs after inhalation of infective fungal propagules in the course of activities involving soil management and may progress acutely or chronically to cause clinical disease, chronic manifestations being most common, especially in rural workers. The lungs are the most affected organs in chronic PCM, while the mononuclear phagocyte system is involved in the acute “juvenile” cases of this mycosis [1]. Rio de Janeiro state is an important endemic region for this mycosis, and there has recently been an increase in the incidence of acute PCM forms in urban areas [2].

When COVID-19 emerged in Brazil in late February 2020 [3], we expected to observe a clinical impact in individuals with PCM, especially in patients with the chronic presentation of the mycosis with pulmonary impairment. On the other hand, COVID-19 shares similar clinical signs with endemic pulmonary mycoses, which can hamper the diagnosis of neglected fungal diseases [4]. These overlapping clinical signs are mostly related to the pulmonary and upper airway involvement of COVID-19 and chronic PCM, both leading to respiratory symptoms such as cough, hoarseness, and dyspnea, while acute PCM rarely affects these organs. In 2021, Heaney et al. [5] reviewed the interaction between COVID-19 and coccidioidomycosis, analyzing the risk factors and the implications of this co-infection, and highlighted how the COVID-19 pandemic might exacerbate delays in the diagnosis of the mycosis. Similarly, the difficulty of diagnosing PCM during hospitalization through the COVID-19 pandemic has also been reported, resulting in delayed diagnosis of PCM [6]. The confounders of overlapping clinical manifestations may explain in part the absence of new case reports of PCM and COVID-19 co-infection.

In 2020, we reported the first case of COVID-19 and PCM co-infection in a young male patient, and discussed the clinical profile and severity of this association [7]. Since this first report, no other cases of this co-infection have been recorded in the literature to date. Given the lack of additional publications and information about co-infections with PCM and COVID-19, we sought to characterize the occurrence and presentations of COVID-19 in a cohort of patients with PCM at a reference center for infectious diseases in a PCM endemic region.

Methods

Results

In the period of study, we identified six patients with COVID-19 among 117 patients evaluated PCM, including the patient we previously reported [7]. Most of them (88.3%) came from Baixada Fluminense, an urban region with low socioeconomic conditions, where recently an increase in acute PCM case numbers was documented [2]. Four patients had laboratory confirmed COVID-19, one had a negative test but presented typical radiographic findings of COVID-19 (Fig 1), and one, although not tested, had flu-like symptoms after a close contact with a suspected case, but was no longer symptomatic at the time of our routine consultation. Table 1 depicts the main clinical characteristics of the patients included in this study.

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Fig 1.

(A) Chest tomography from a patient included in this study (case 2) showing peripheral and coalescent ground-glass opacities better seen in the right lung. This 57-year-old male patient was infected by Paracoccidioides sp. in the past, while developing construction activities during 20 years. He was a heavy smoker, developed chronic paracoccidioidomycosis (PCM), and was admitted at our institution presenting a 9-month painful tongue lesion, evolving with emaciation, cervical lymph nodes enlargement, and lung disease. PCM was diagnosed through histopathology from biopsies of the oral lesion and cervical lymph node, which revealed a chronic granulomatous inflammatory process along with multiple budding cells compatible with Paracoccidioides spp. yeast-like cells, better seen in the Grocott’s methenamine silver stain (B). The patient was treated with itraconazole and trimethoprim/sulfamethoxazole for 35 months due to poor adherence. When COVID-19 infection occurred, this patient was under the post-therapeutic follow-up, and presented lung sequelae, such as severe pulmonary fibrosis and chronic obstructive pulmonary disease (COPD). His COVID-19 disease was severe, requiring invasive ventilation, and he died four days after hospitalization.

https://doi.org/10.1371/journal.pntd.0011322.g001

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Table 1. Summary description of the cohort of patients with paracoccidioidomycosis and COVID-19 co-infection.

https://doi.org/10.1371/journal.pntd.0011322.t001

Three patients presented with mild symptoms of COVID-19, including low-grade fever, headache, and other common cold symptoms (cough, sneezing and nasal discharge). The other three patients required hospitalization due to hypoxia. One patient was considered to have moderately severe disease and was treated with high-flow nasal oxygen, corticosteroids, and favipravir. He had 13 days of intensive care unit (ICU) stay, and did not develop additional complications of COVID-19. Both patients with severe COVID-19 required invasive mechanical ventilation. One patient had acute PCM under treatment with pulmonary involvement and we previously reported this case [7]. At the time that we published the description of his case (August 2020) this patient was still hospitalized. Although recovered from acute disease, he subsequently developed a dilated cardiomyopathy as a complication of COVID-19 after discharge, but recovered and was lost follow-up after 17 months of PCM treatment. The other patient with severe COVID-19 had chronic PCM under post-therapeutic follow-up with severe pulmonary fibrosis, chronic obstructive pulmonary disease (COPD), and, despite treatment in the ICU with mechanical ventilation, corticosteroids, and antibiotics, died four days after admission due to rapid decompensation due to complications of COVID-19. Although only two patients were under treatment for PCM when they had COVID-19, there was no need to change the therapeutic regimen for PCM in these cases. None of the patients from this study presented TB co-infection.

Discussion

Invasive fungal infections have been an important complication of COVID-19 infection especially in severe disease, with a significant incidence of mucormycosis, aspergillosis and candidiasis [9–11]. Due to these complications, consensus guidelines for the management of certain mycoses in the setting of SARS-CoV-2 have been established [12]. Concurrent COVID-19 and endemic systemic mycoses have been well documented and a recent review indicates the occurrence of this condition worldwide [13]. In this review, the authors identified seventy-eight patients with COVID-19 associated with an endemic systemic mycosis. Coccidioidomycosis was most frequently reported, followed by histoplasmosis, with cases occurring mostly in the Americas. Blastomycosis and PCM accounted for one case each, in the U.S and Brazil, respectively. The Brazilian case was initially published by our group and was also herein updated to report his final outcome, which was not made in the previous publication [7]. To date, emergomycosis and talaromycosis associated with COVID-19 have not been reported. It has been noted that the immune dysregulation and inflammation occurring in COVID-19 likely leads to a higher risk of symptomatic disease and reactivation of endemic mycoses in individuals with previously latent infections [12]. In addition, the use of corticosteroids to treat severe COVID-19 induced an immunosuppressive condition that would contribute to reactivation.

In our patient populations, we did not observe an increase in PCM cases following COVID-19 as reported for other endemic mycoses [14]. Therefore, the immune alterations induced by this viral disease or its treatment does not seem to promote a reactivation of latent infection due to Paracoccidioides spp. or to exacerbate PCM.

Five of the six patients herein studied had acute PCM, without prior comorbidities. At present, it is unclear whether this finding is due to the new epidemiological profile of PCM in the state of Rio de Janeiro characterized by a higher incidence of acute cases [2] or whether this is related to an increased susceptibility of the immune response of acute PCM against SARS-CoV-2. Among these acute PCM cases, mild COVID-19 prevailed, which is consistent with the scarcity of lung impairment in acute PCM, although it could also be due to a control of PCM disease at the time of the COVID-19 diagnosis in these mild cases. In fact, the patient with acute PCM who developed severe COVID-19 had severe active PCM with pulmonary involvement (pleural effusion) [7]. On the other hand, the death of the single patient with severe COVID-19 and a history of chronic PCM, but with pulmonary sequelae and COPD, was attributed to the infection with SARS-CoV-2. Therefore, acute or chronic lung involvement in PCM may contribute to a worse outcome of COVID-19.

It is noteworthy that itraconazole, which is currently the first line oral antifungal drug to treat PCM, has in vitro activity against SARS-CoV-2 [15–17]. Although this antifungal drug has not been proven to be effective for COVID-19 treatment [16], PCM patients receiving itraconazole would have experienced a protective effect of this drug against SARS-CoV-2, by reducing viral replication rates. Additionally, at least 14 non-antifungal drugs with potential activity against SARS-CoV-2 have shown in vitro antifungal activity against P. brasiliensis [18]. Therefore, this may also have contributed to protecting individuals against disease due to Paracoccidioides spp., which may perhaps explain, in part, the absence of post-COVID-19 PCM cases. The patients from this study did not receive any drugs with known clinical activity against SARS-CoV-2, except favipravir, which does not have antifungal activity against Paracoccidioides spp. [18]

Our findings suggest that co-infection with SARS-CoV-2 and Paracoccidioides manifests in mild to lethal outcomes with increased odds of poor outcomes when the lungs are compromised due to PCM. As COVID-19 and chronic PCM share similar clinical aspects and this mycosis is neglected, it is likely that COVID-19 has been hampering PCM diagnosis, which can explain the absence of reports of new co-infected cases in regions endemic for Paracoccidioides sp. In addition, according to the authors’ personal experience, acute PCM cases continue to be misdiagnosed as other diseases such as tuberculosis and lymphoma. Therefore, clinicians must be aware of this possible association of increased COVID-19 severity in PCM endemic areas. The research advances of new therapeutic options for COVID-19 and studies repurposing drugs to both PCM and COVID-19 may help to understand the epidemiology of this co-infection, as well as to promote advances in the therapeutic management of both diseases. Notably, mild COVID-19 cases, especially after vaccination, can account for the lack of co-infection reports. Regardless, more studies are needed for a better comprehension of this important issue, and mandatory reporting of PCM should be a public health priority.

Acknowledgments

The authors thank Dr. Thiago Lima Barreto de Campos and Dr. Leonardo Pereira Quintella for providing the radiological and histopathological images of a patient from this study. The authors are also sincerely grateful for the support of the Evandro Chagas National Institute of Infectious Diseases (INI/Fiocruz).