First Report of the Pulmonary Parasite Lophomonas blattarum in Ahvaz Province, Khuzestan: Case Report and Literature Review

Abstract

The flagellate protozoan parasite known as Lophomonas blattarum primarily infects the respiratory tract. Infections in humans are infrequent but have been observed, especially in immunocompromised individuals. Our study presents the first case of L. blattarum infection in the lungs of a patient from Ahvaz Province in Khuzestan. A 63-year-old man who had previously suffered from pulmonary embolism presented with persistent symptoms of chronic cough, hemoptysis, and dyspnea. Radiographic studies revealed the presence of bilateral pulmonary infiltrates. L. blattarum trophozoites in the sputum were identified by examining the morphology and motility of the trophozoites. Subsequent treatment with metronidazole resulted in significant improvement in the patient’s condition. This case highlights the importance of considering L. blattarum as a potential respiratory pathogen, especially in regions with a high prevalence of cockroach infestation.

INTRODUCTION

A flagellating protozoan parasite known as Lophomonas blattarum is associated primarily with cockroach infection, leading to the respiratory disease.[1,2,3] Human infections are relatively infrequent but have been documented, particularly in individuals with compromised immune systems.[4] This study provides an account of the first confirmed instance of L. blattarum infection in the Ahvaz region of Iran. Lophomonas blattarum has long been recognized as a respiratory parasite in various cockroach species[5]; however, its prevalence and clinical significance in human respiratory infections have only recently been investigated.[6] Notably, individuals with compromised immune systems, including those with respiratory disorders or immunosuppressive conditions are at increased risk of contracting L. blattarum infections in humans.[7,8,9,10] Although the precise method of transmission to humans remains unknown, it is generally accepted to occur through either direct contact with contaminated objects or inhalation.[11]

Cases of L. blattarum infection have been reported primarily in China, but several studies have reported cases in other countries [Table 1].

Table 1.

Overview of L. blattarum infections in humans from 2014–2023

Reported case no.	No. of cases	Sex/age of patients	Year	Country	References
1	1	F/21y	2014	China	[21]
2	1	F/31y	2014	Iran	[23]
3	1	M/70y	2014	China	[24]
4	1	M/60y	2015	India	[25]
5	1	M/2y	2017	Mexico	[26]
6	1	F/34y	2017	India	[27]
7	1	F/28y	2019	China	[28]
8	1	M/68y	2019	Türkiye	[29]
9	1	F/40y	2019	Iran	[30]
10	1	F/29y	2019	Malaysia	[8]
11	6	(2M+4F)/(18–79y)a	2021	Spain	[31]
12	1	M/29y	2021	Peru	[32]
13	1	F/33y	2022	Iran	[33]
14	1	F/44y	2022	Iran	[34]
15	1	M/57y	2022	Iran	[35]
16	9	(2M+7F)/(1–17y)a	2022	Iran	[36]
17	1	F/43y	2023	India	[37]

^aSex composition/age range

CASE REPORT

A 63-year-old man, who had undergone liver hydatid cyst surgery 5 years prior and had a medical history of hypertension, congestive heart failure (with an ejection fraction of 35%), and recent pulmonary embolism presented with symptoms of fever, chills, cough, shortness of breath, and bilateral alveolar lung lesions. He was admitted to Imam Khomeini Hospital, affiliated with Ahvaz Jundishapur University of Medical Sciences, due to the severity of his condition. Initial investigations revealed a positive blood culture for E. coli infection, and appropriate antibiotic therapy was initiated. The patient’s condition improved, and he was discharged.

However, he later experienced the recurrence of symptoms, including persistent cough, sputum, and multiple cavitary lesions in the right lower lobe (RLL) and left upper lobe (LLL), along with mild alveolar changes and pleural effusion in the left lower lobe, suggestive of para-pneumonic effusion. The patient was readmitted for further evaluation.

Numerous diagnostic procedures were conducted during hospitalization. Bronchoscopy findings were normal, and tests for serum and bronchoalveolar lavage galactomannan, acid-fast bacilli (AFB), and rheumatologic markers returned negative results. Hydatid cyst IgG testing was mildly positive, but IgM was negative. The patient responded well to antibiotic treatment and was discharged. However, subsequent CT scans revealed worsening scattered nodular lesions over time [Figures 1 and 2]. A transthoracic biopsy was performed to assess the lung condition, but the results revealed either necrosis or edema.

Figure 1.

Alveolar pattern and abscess formation in RLLs and parapneumonic effusion in LLL. RLL = right lower lobe, LLL = left upper lobe

Figure 2.

New nodular pattern

Further evaluation included repeat bronchoscopy, which revealed white egg-shaped discharges in the LLL. Bronchoalveolar lavage indicated 10% eosinophils. Tests for hydatid cysts were negative, but infection with L. blattarum was identified. Metronidazole was initiated to treat L. blattarum infection, and patient progress was closely monitored considering the scattered nodular lesions observed on the CT scan.

Methods for detecting Lophomonas blattarum and differentiating Lophomonas blattarum from ciliated cells

During patient readmission, the diagnostic procedures included a detailed examination of bronchoalveolar lavage (BAL) fluid. Microscopic analysis was pivotal in identifying Lophomonas blattarum trophozoites. The key diagnostic features observed included the following:

• Morphology: The trophozoites exhibited a pear-shaped structure with tufted flagella distinguishable from the uniform appearance of ciliated epithelial cells.

• Motility: Lophomonas demonstrated active motility under a microscope, a characteristic absent in ciliated epithelial cells, which remain stationary [Figure 3].

Figure 3.

Lophomonas with tufted and irregular multiple flagella is visible in a direct smear of a BALF sample (arrowhead)

Giemsa staining was used to enhance visualization, revealing the flagella and undulating membrane unique to Lophomonas.

To avoid misdiagnosis, a comparative analysis of epithelial cells and Lophomonas was performed, with a focus on differences in cell size, structure, and motility. Advanced diagnostic confirmation via polymerase chain reaction (PCR) was not employed in this case but has been reported in the literature as an effective method for definitive identification.

This case report highlights the first documented case of L. blattarum infection in Khuzestan, Ahvaz Province. This report highlights the unique clinical presentation and diagnostic challenges associated with this condition.

DISCUSSION

The clinical significance of L. blattarum as a respiratory pathogen remains debated. While it is considered a rare cause of respiratory infections, this case highlights its potential importance, particularly in immunocompromised individuals or those with preexisting pulmonary conditions. The patient’s history of chronic obstructive pulmonary disease (COPD) may have increased susceptibility to L. blattarum infection, aligning with symptoms and presentations documented in prior reports.

Diagnostic challenges

The diagnosis of Lophomonas blattarum is inherently challenging because of its nonspecific clinical presentation and morphological resemblance to ciliated epithelial cells.[12,13] The parasite primarily affects the bronchi, causing symptoms such as cough, dyspnea, and fever—manifestations that mimic pneumonia or bronchitis. In this case, the diagnosis was confirmed through microscopic examination of bronchoalveolar lavage (BAL) fluid, which revealed characteristic pear-shaped, flagellated organisms with undulating membranes[14,15,16] [Figure 3 and Video Supplementary 1 data].

Staining techniques, including Giemsa, Papanicolaou, or Wright stains, were utilized to enhance visibility and facilitate differentiation from human epithelial cells. While cultivation is theoretically possible, it is rarely employed because of the specific conditions and time needed. Polymerase chain reaction (PCR), which can amplify and identify L. blattarum DNA with high sensitivity, represents a more accurate diagnostic method.[17,18,19] However, PCR was not used in this case, reflecting the diagnostic limitations in many clinical settings.[20]

Clinical implications

The clinical presentation of L. blattarum infections often mimics other respiratory diseases, such as pneumonia or bronchitis, making diagnosis even more challenging. In this case, the patient’s symptoms—persistent cough, dyspnea, and cavitary pulmonary lesions—initially led to a differential diagnosis that included bacterial infections and hydatid disease. The recurrence of symptoms and progression of pulmonary lesions underscore the need for a broader diagnostic approach [Table 2].[21]

Table 2.

Review of clinical and radiological data from 30 cases of L. blattarum infection (from 2014 to 2023)

	Analysis of clinical and radiological data	No. of cases (%)
1.	Diagnostic specimens for respiratory tract infections	27 (100)
	BAL fluid	21 (77.7)
	A swab of pharyngeal sputum	7 (25.9)
	Throat swab	3 (11.1)
	Bronchial swab	2 (7.4)
2.	CT RESULTS	16 (100)
	Two-dimensional consolidation	6 (40)
	Frosted glass opacity	4 (26)
	Nodular opacities	3 (20)
3.	Radiological manifestations	9 (100)
	Spotted or streaky shadow	6 (66.6)
4.	Infection foci	30 (100)
	Infection of the respiratory tract	28 (93.3)
	Urinary tract infection	1 (3.3)
	Sinus infection	2 (6.6)
5.	Clinical signs and testing of the peripheral blood	27 (100)
	Sputum-filled cough	24 (88.8)
	Eosinophilia	7 (25)
	Fever	16 (59.2)

Significance of underlying conditions

The presence of underlying diseases, such as COPD, significantly influences both the risk of infection and the diagnostic process. Immunocompromised individuals and those with chronic respiratory disorders are disproportionately affected, as their compromised immune defenses provide an environment conducive to infection. The recurrence of symptoms and progression of pulmonary lesions in this case highlights the need for vigilant follow-up and consideration of parasitic infections in differential diagnoses.[22]

Therapeutic implications

In this case, treatment with metronidazole resulted in significant clinical improvement, which is consistent with its known efficacy against anaerobic protozoa. This finding aligns with the literature supporting metronidazole as a first-line therapy for L. blattarum infections. Alternative agents such as tinidazole have shown promise but require additional validation through clinical trials. Early diagnosis and prompt treatment are critical for preventing complications, particularly in severe or recurrent cases.

Epidemiological insights

The increasing number of reported L. blattarum infections worldwide suggests that this parasite may be underdiagnosed rather than rare. Its association with cockroach infestations implicates these insects as potential reservoirs, although the exact mechanisms of human transmission—whether through inhalation or direct contact with contaminated materials—remain speculative. This case underscores the need for heightened awareness, especially in regions with high cockroach prevalence and in settings where immunosuppressed populations are at greater risk.

In addition to the 14 cases reported in Iran, L. blattarum infections have been documented in Peru, Spain, Mexico, and Malaysia in recent years. Notably, two-thirds of the 30 clinical cases occurred in the last three years. The symptoms and signs of L. blattarum infection closely resemble those of pneumonia or bronchitis, rendering accurate diagnosis complex. The presence of underlying disease significantly influences the diagnosis, with 13 out of 30 patients demonstrating comorbid conditions. These underlying diseases encompass three different ailments, namely, metabolic disease, asthma, allergic rhinitis, and bronchitis, as well as a damaged immune system and, notably, severe chronic wasting disease.

Future directions

To improve the understanding and management of L. blattarum infections, several key areas require further research. First, the development of standardized diagnostic protocols that combine microscopy, staining, and molecular methods, such as PCR, is essential to increase diagnostic accuracy and reduce misidentifications. Second, large-scale epidemiological studies are needed to determine the true prevalence of L. blattarum infections, particularly in endemic and underreported regions. Third, investigating the environmental and biological factors contributing to its transmission, including the role of cockroaches and other potential reservoirs, will provide insights into prevention strategies. Fourth, studying the long-term outcomes of treated patients, including recurrence rates and the potential for drug resistance, will inform clinical management and therapy optimization. Together, these research efforts will significantly advance the understanding and control of L. blattarum infections globally.

CONCLUSION

This study emphasizes educating medical personnel about L. blattarum as a potential cause of respiratory infections, particularly in immunocompromised people. An early and accurate diagnosis is crucial to start the right course of therapy and stop future complications. The prevalence, clinical signs and symptoms, diagnostic procedures, therapeutic approaches, and long-term effects of L. blattarum infections should all be the subject of additional study.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Ethics approval and consent to participate

The study was approved by the Medical Research Ethics Committee of Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran (IR.AJUMS.REC.1402.65).

Conflict of interest

The authors declare that they have no conflicts of interest.

Funding Statement

The authors wrote this article without any financial assistance.