Unveiling Balantidium coli: A rare protozoan causing a series of cases of dysentery in Rajasthan and review of literature

ABSTRACT

Balantidium coli is the largest, uncommon, and only ciliate parasite that infects humans and is more common in tropics and subtropical regions. It is mostly asymptomatic, but can cause diarrhea and abdominal pain and sometimes leads to perforation of the colon. It is harbored in animals, particularly among pigs in hotter environments and monkeys in the jungles. If not treated on time, it may lead to perforation of the large intestine, peritonitis, appendicle involvement, etc. It is more common in immune-compromised individuals, particularly in those living in poor hygienic conditions. Retrieval of rare parasites was possible only because of prompt stool transport and its early processing. There are only few previous reports regarding the pediatric cases of balantidiasis, and there is a little information about its clinical signs and treatment. Here, we report a case series of B. coli infection presenting as an acute diarrheal disease from Rajasthan.

Introduction

Balantidium coli are harbored in animals, particularly among pigs and monkeys in jungles. So, human infections occur more frequently among pig ranchers and pig-raising locals than in the normal population, as their sanitation is inadequate and hygiene is poor.[1] B. coli is the only largest, uncommon, and pathogenic member of ciliate family Balantidiidae that infects humans.[2] Infection in humans is generally a rare encounter, which is acquired by ingestion of food and water contaminated with cysts. Majority of patients are asymptomatic carriers. Trophozoites are capable of attacking intestinal epithelium, leading to ulceration, and dysentery similar to that of amoebic dysentery.[3]

Case Series

Case 1

A 9-month-old girl child was presented to pediatric outpatient department with complaints of repeated episodes of fever from last 3–4 days and loose stools. Fever was acute in onset and gradual in progression. The fever was undocumented, but high grade to touch according to attendant, relieved on medications, and was not associated with joint pain, rashes, and chills or rigors. The second complaint was acute diarrhea since 3 days, with six to eight episodes/day. Patient had also experienced an episode of vomiting during hospital admission, which mainly consisted of undigested food particles and was non-projectile, non-blood tinged, and non-purulent. After admission to pediatric intensive care unit, the infant still experienced abdominal pain, fever, vomiting, and more than six to eight liquid greenish stools/day. On physical examination, she had dry tongue, sunken eyes and depressed fontanel, 166/min pulse rate, respiratory rate 30/min, 99% SpO₂, and temperature 100.4°F. Her abdomen was soft. Pulmonary, cardiac, and neurologic examinations were normal. The infant was started on symptomatic treatment with inj. ceftriaxone 350 mg intravenous 12 hourly, and the routine investigations were done.

Blood investigations on admission revealed deranged complete blood count with hemoglobin 6.4 gm/l, hematocrit 22.4%, mean corpuscular volume 52.5/l, mean corpuscular hemoglobin concentration 28.5 g/dl, red cell distribution width 20.3%, and platelet distribution width 17.3 fl. Peripheral blood film showed microcytic hypochromic anemia with anisopoilocytosis in the form of tear drop cells. Her total serum (S.) iron and total iron binding capacity were <10.1 μg/dl and 379.8 g/dl, respectively. Urine routine was within normal limits (WNL). Liver function test was done; S. glutamic oxaloacetic transaminase was high (54.2 U/l), while S. glutamic pyruvic transaminase was normal (26.2 U/l). She had raised C-reactive protein (34.6 U/l), and her S. electrolytes were also deranged (S. sodium- 131.4 mol/l, S. chloride- 108.5 mol/l, S. potassium- 4.24 mol/l). There was nothing remarkable in her medical history. She was not taking any medications and was immune competent. There was no history of travel or chronic inflammatory bowel disease. Chest-X-ray and ultrasound abdomen revealed no abnormalities.

The patient was living with her parents in an urban area with no history of contact with animals. She was on breast feed for the first 5 months and later, she was shifted to buffalo milk due to some medical reasons (mother). But the milk she was drinking was directly mixed with tap water coming directly from the tube well. The stool sample was sent for routine microscopy and occult blood test. On macroscopic examination, the stool specimen was loose with visible blood. Routine stool microscopy showed presence of many ciliated motile trophozoites and cysts of B. colias shown in Figure 1 and occult blood was positive. Stool examination was negative for bacteriological pathogens. The patient was treated with metronidazole 500 mg one time daily for 3 days and she improved gradually. Further work-up on the patient showed no extraintestinal manifestations. The patient slowly improved with therapy and was advised for follow-up.

Figure 1.

Microscopic examination showing ovoid to oblong ciliated trophozoite of Balantidium coli

Case 2

A 1-year-old child presented with loose stools, jaundice, nausea and vomiting, and fatigue with no signs of dehydration. On examination, the abdomen was tender and protruding. His hemoglobin was low (9.2 g/dl), platelets (667 × 10³/µl), eosinophils (0.9%), low mean corpuscular volume (63.2 fl) and mean corpuscular time was raised (0.534%). His liver function tests and thyroid function tests were WNL. He was suspected of celiac disease (tissue transglutaminase-IgA test was high [>100 AU/ml]). Patient was advised abdominal sonography and endoscopy, but his parents refused to do the same. We received his stool sample to look for any parasitic cause. On macroscopic examination, the stool was yellow and loose, with no specific odor, no visible parasitic segments, and no blood and mucus. On microscopic examination, many motile trophozoites and cysts of B. coli were seen as shown in Figure 1. He was living in an urban area, but he had one visit to his ancestral place and after that, he started experiencing these manifestations. So, the final diagnosis was B. coli dysentery along with celiac disease. He was treated with metronidazole 500 mg one time daily for 3 days and he improved gradually.

Discussion

B. coli are free-living protozoan parasites found mostly in the tropics and subtropics because of variables like climatic variation and social practices. Mature cysts are passed in stool and remain viable for up to 2 weeks in the environment.[4] So, stool microscopy plays a major role in the diagnosis of parasitic causes of dysentery/diarrhea.

Balantidiasis is rare in healthy people, but is more common and fatal in immune-compromised people. In addition, pervasiveness of organic entity was accounted for to be around 0.02%–1%, which might fluctuate as indicated by the geological area.[5] Very few cases of balantidiasis have been reported in India so far, showing the rarity of this parasitic infection [Table 1].[6,7,8,9,10]

Table 1.

Review of literature of Balantidium coli cases reported in India[6,7,8,9,10]

Ref. no.	Author, year of publication	Sample size	Region	Case details	Diagnosis	Remarks
6	Bose et al. (2023)	1	Chennai	Acute diarrheal disease in a diabetic	Stool microscopy	Even though rare in India, it can be kept in mind as a differential diagnosis for a patient presenting with large bowel diarrhea
7	Gupta et al. (2017)	2	Ranchi	Fever, malaise, anorexia.	Urine microscopy	Before reporting a case of urinary balantidiosis, fecal contamination must always be ruled out because of rarity of such a case
8	Kapur et al. (2016)	1	New Delhi	Liver abscess	Microscopic wet mount examination of the aspirated pus	As per our knowledge, this is the first case of B. coli being isolated from a liver abscess in Indian literature. Whether it reflects the increasing virulence of the organism or increased susceptibility of human beings to this protozoan needs to be debated
9	Khanduri et al. (2014)	1	Uttarakhand	Patient with acute renal failure	Urine microscopy	Microscopic examination of fresh urine sediments can help in easily diagnosing this large parasite, based on its characteristic morphology and rapid spiraling motility
10	Bandyopadhyay et al. (2013)	1	West Bengal	Mild fever, dysuria, increased frequency of micturition and pelvic pain	Urine microscopy	B. coli, a rare urinary pathogen, should come in the differential diagnosis in elderly debilitated patients presenting with dysuria and hematuria

In the present study, an infant had no history of contact with pigs, domestic cattle, etc. She might have got infected through contaminated milk, as the milk she was consuming was mixed with tap water coming out directly from a tube well. So, there is a high possibility of acquiring this parasitic infection through water. In the second case, there was a history of visit to rural area, from where the patient might have got the infection. So, these cases underline that B. coli should also be considered as a possible pathogen in children, even if they have no contact with pigs.

Conclusion

Retrieval of rare parasites was possible only because of prompt stool transport and early processing of it. Even though rare in India, balantidiasis can be kept in mind as a differential diagnosis for a patient presenting with diarrhea/dysentery, especially infants and children. Clean water and hygienic sanitary conditions are most efficient strategies which can be ensured to prevent human infections.

Declaration of patient consent

The authors certify that appropriate patient consent was obtained.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil