Blastomycosis is a systemic mycosis caused by ther-mally dimorphic fungi, Blastomyces dermatitidis and B. gilchristii.  Infection is acquired by inhalation of the organism, followed by its multiplication in the lungs and frequent hematogenous dissemination. Direct inoculation of the fungus is a rare means of infection (Sarcante and Woods, 2010; Benedict et al., 2012). The incubation period varies from 2 to 15 weeks, and the clinical spectrum ranges from asymptomatic to life-threatening infections involving acute respiratory distress syndrome or extra pulmonary dissemination (Sarcante and Woods, 2010) Most identified cases involve pulmonary infection that manifests similarly to other causes of pneumonia (Benedict et al., 2012; Hayle et al., 2020; Schwartz et al., 2018). 

The clinical similarities between blastomycosis and other pulmonary infections often result in diagnostic delays and unnecessary empiric antimicrobial drug treatment for suspected bacterial pneumonia (Schwartz et al., 2018). The endemic areas for blastomycosis include states and provinces along Ohio, Mississippi, Missouri, and St. Lawrence River, Canada, Europe, Central America, and India (Sarcante and Woods, 2010; Thompson et al., 2017). 

In reviews of autochthonous cases of blastomycosis from reported from Africa and India (Schwartz et al., 2021; Randhawa et al., 2013), it was found that 100 patients with this disease were reported from12 African countries, whereas only 10 were described from India. Blastomyces gilchristii is restricted to select Canadian provinces and northern US states, specifically, Alberta, Saskatchewan, British Columbia, Ontario, New York, Minnesota, and Wisconsin (Thompson et al., 2017). Schwartz et al. (2019) des-cribed a new species of Blastomyces, Blastomyces helicus, and an emerging pathogen for humans and animals in western Canada and United States. No case of B. gilchristii or B. helicus infection is known from Indian subcontinent.

A thorough search of the literature was made on blas-tomycosis cases reported in countries in the Indian subcontinent in PubMed, MEDLINE, Med Facts using sets of different keywords, viz. India, Bangladesh, Pakistan, Nepal, Bhutan, Sri Lanka, Blastomyces, systemic/deep mycosis, etc. Cross references in the relevant articles were used to download the papers and extract relevant information for incorporation in the review.

Literature search revealed that the first report of Blastomyces dermatitidis infection from India was by Ganguli in 1925, described as a very common affl-iction prevalent in the rainy season, generally affecting t10-40% coolies working in the tea gardens of Duars situated at the foot of hills in east central Himalayas. From the lesions described as multiple warty ulcerated growths sometimes appearing granuloma to us and the detection of roundy east like cells scraping s of the lesions described, this report evidences a misdiagnosis of Blastomycosis as these are clinical and histological features of chromo blastomycosis. Again in1925, Panja described a case of generalized Blastomycosis with no dularsk in lesions and yeast-like cells in scrapings. The diagnosis of these two cases is dubious as pointed out in a review by Randhawa et al. (2013). 

These authors have reviewed eleven cases of chromo-blastomycosis including four authentic cases (in-cluding two autochthonous and two imported ones) and seven misdiagnosed ones reported in India up to 2013. The two autochthonous cases comprised one each from Uttar Pradesh and Madhya Pradesh.  Our review has located three more authentically diagnosed indigenous cases in India including one each from Arunachal Pradesh (Kumar et al., 2014) Himachal Pradesh (Sharma et al., 2015) and Kerala (Kumar et al., 2019). One authentically diagnosed case each was reported from Bangladesh (Bhuiyan et al., 2015) and Nepal (Gandhi et al., 2015). Also, of five misdia-gnosed cases published from India, one each was from Haryana (Rana et al., 2015) and Uttar Pradesh (Shekhar et al., 2016) two from Gujarat (Patel et al., 2014; Hongal & Geije, 2016) and one from Andhra Pradesh (Rao et al., 2013). The salient clinical features of autochthonous authentic cases of blastomycosis reported from India, Bangladesh and Nepal, and the misdiagnosed ones from India after 2013 are described in Table 1. The state-wise distribution of three Indian authentic indigenous cases of blastomycosis known so far after 2013 in Fig. 1.

Abbreviations

CNS-Central nervous system, CSF-Cerebrospinal fluid, h/o- History of, H & E-Haematoxiin and Eosin, PAS-Periodic Acid-Shiff, GMS-Groctts methenamine silver, FNAC- Fine needle aspiration cytology, ATT-Antitubercular therapy

The clinical and diagnostic features of the cases reported from India up to 1997 have been described earlier (Randhawa et al., 2013), Though the total number of authentic indigenous cases known form India so far is only six; their locations represent several parts of India, indicating that many more cases of Blastomycosis possibly exist in country but have not been diagnosed. Prolonged blastomycosis results in-chronic cough, weightloss, and hemoptysis (Benedict et al., 2012). Pulmonary tuberculosis is quite common in the Indian subcontinent and is often treat dem-pirically. Mycological investigation of tuberculosis cases, negative for culture and AFBs mear, and not responding to anti-tubercular therapy may reveal some cases of blastomycosis. The areas of environmental distribution of B. dermatitidis in India remain undetermined et al. Isolation of B. dermatitidia has been reported from the lungs of the bat, Rhino-pomahardwickeihardwickei (Khan et al., 1982) and the liver of same bats pieces (Randhawa et al., 1985) in India. It is not known whether bats could be are a reservoir for human infections due to this fungus. In the USA, blastomycosis quite common in dogs resi-ding in or visiting enzootic areas and the incidence of blastomycosis in dogs is eight to ten times higher than that in humans (Schwartz et al., 2018). Most dogs infected by inhaling spores of B. dermatitidis from soilor organic debris. Detection of Blastomycosis in dogs is a sentinel of possible occurrence of human cases of this disease (Benedict et al., 2012, Schwartz et al., 2018).

Fig. 1: The state-wise distribution of three Indian authentic indigenous cases of blastomycosis known so far after 2013. 

Table 1:  Salient clinical features of all the cases of blastomycosis reported after 2013 from the Indian sub-continent

Blastomycosis primarily acanine disease and occurs in dogs about ten times more in humans than that in dogs The review by Randhawa et al. (2013 mentioned only one case of can in blastomycosis from India, mani-festing as pulmonary infection in a Mongrel dog found dead in Bareli, Uttar Pradesh. Human cases of blasto-mycosis covered in our review originated from several distant locations in India, Blastomycosis is primarily a canine disease (Schwartz et al., 2018) Surveillance for more canine cases in several parts of India and other countries in the Indian subcontinent may facilitate detection of endemic foci of B. dermatitidis for human and animal infections. Possibly many more human cases of blastomycosis exist that have not been recog-nized. A recently developed real-time PCR for identi-fication of B. dermatitidis in culture and tissue and antigen testing in broncho-alveolar fluid (Bal), serum and urine is also useful for diagnosis of Blastomycosis (Sidamonidze et al., 2012; Linder et al.,2021)

The author is incredibly grateful to MS Sonia Sardana-Gugnani of American Express for constructing Fig. 1.

We have no conflict of interest in this research.