Departments of ¹Microbiology and ²Pulmonary Medicine, All India Institute of Medical Sciences, Nagpur, Maharashtra, India.

Parasitic infections are a major health concern that affects millions of people worldwide. Globalisation, climate changes, increased international travel, and increasing numbers of immunocompromised individuals have contributed to the increased vulnerability of population to parasitic diseases [1]. A diverse range of helminths and protozoa has the potential to impact the respiratory system, with clinical manifestations varying from asymptomatic infection to severe and life-threatening conditions.

A 44-year-old male farmer, residing in Maharashtra, India presented with recurrent history of febrile illness for six months. It was characterised by high-grade fever with chills, headache, cough with expectoration, and shortness of breath. He was treated at various hospitals, with parenteral and oral antibiotics, without improvement, before admission at our facility. The patient had a history of mild coronavirus disease 2019 (COVID-19) in April 2021 two months before the onset of presenting complaints. The patient had no history of any other underlying co-morbid condition. On admission, the patient was febrile (101°F), and tachypneic (Respiratory rate - 28/min). Other vital parameters were within normal limits. During the examination of the respiratory system, bronchial breathing was observed in the left lower zone of the lung. Laboratory analysis indicated a total leukocyte count of 14,200/cu.mm, with 84% polymorphonuclear cells, 9% lymphocytes, and 4% eosinophils. His liver function tests and kidney function tests were within normal limits. Cultures of blood, sputum, and urine did not yield the growth of pathogens. The chest X-ray displayed interstitial haziness and consolidation in the left mid and lower zones, along with mild cardiomegaly. Subsequent fibreoptic bronchoscopy revealed a smooth, lobulated growth obstructing the opening of the left lingular bronchus [Fig.1]. BAL fluid with biopsy tissue were obtained. Wet mount examination of BAL sample under microscope revealed many live, oval, approx. 20-30 µm in size, motile ciliary structures with granular cytoplasm [Fig.2 and Video 1]. Morphologically it was identified as Lophomonas blattarum. Giemsa and Trichrome staining were performed on the BAL sample smear to validate the observations. Trichrome stain smear proved instrumental in distinctly recognising and distinguishing the oval trophozoite of Lophomonas with a tuft of flagella from bronchial cells exhibiting columnar shape, terminal bar, and apical cilia [Fig.3,4]. KOH examination and acid-fast bacilli staining of BAL sample were negative. Cytology report of biopsy tissue was negative for malignant cells. No organisms were cultured from BAL sample. The patient was initiated on a course of oral Metronidazole at a dosage of 400 mg three times a day for a duration of 14 days. A positive response was observed, as evidenced by improvement in a subsequent chest X-ray and the absence of the protozoa in a repeat bronchoalveolar lavage sample.  

Lophomonas are anaerobic, free-living multi-flagellate parabasalids existing in diverse aquatic settings, including freshwater, brackish water, and marine environments. Lophomonas comprises two species: Lophomonas blattarum and Lophomonas striata. Both are found as a commensal agent in the hind-gut of certain arthropods such as termites and omnivorous roaches, several species of cockroaches including Blatta orientalis, Periplaneta americana, and Blattella germanica. The parasite demonstrates both trophozoite and cyst phases; nevertheless, only the trophozoite stage is observable in human tissue, whereas both forms are visible in the gut of the insect host. It is excreted in the faeces of the host into the environment, where it forms cysts under external environmental conditions. The cyst form may be inhaled and parasitised in the human respiratory tract and can cause sinusitis or broncho-pulmonary infection [8]. It has been incriminated in a variety of other human diseases like gastroenteritis, and diarrhoea and sometimes may also lead to more serious complications such as liver damage, anaemia, and even death. 

As we navigate the complexities of respiratory infections, especially those resistant to conventional therapies, this case serves as a reminder of the importance of thorough investigations and a multidisciplinary approach. Recording instances of such unusual cases in non-endemic regions play a crucial role in advancing our understanding of atypical infections like Lophomonas. This is essential for improving diagnostic approaches, optimising treatment results, and ultimately enhancing the overall management of respiratory conditions. 

Contributors: NG, SN: laboratory diagnostic part, manuscript writing, literature search; SS: manuscript editing, patient management; VS, MM, PT: critical inputs into the manuscript. NG will act as a study guarantor. All authors approved the final version of this manuscript and are responsible for all aspects of this study.

Funding: None; Competing interests: None stated.