Cryptosporidium spp. infection occurring in patients with recurrent pancreatitis and primary Sjögren’s syndrome: A case report

Introduction

Cryptosporidiosis is an infectious disease caused by Cryptosporidium spp. infection, which is prevalent worldwide and is mainly transmitted through the fecal–oral route. Cryptosporidiosis can be contracted as a result of poor personal hygiene, unsanitary dietary and working environments, and contaminated water sources or food.^1,2 The main clinical symptoms of human infection with Cryptosporidium spp. include fever, abdominal pain, diarrhea, and weight loss. These symptoms are similar to those of pancreatitis and Sjögren’s syndrome, often leading to misdiagnosis or missed diagnosis.

Case presentation

The patient, a man in his early 50s, presented with left upper abdominal pain in September 2022, with no known cause, characterized by persistent, vague pain and episodes of paroxysmal aggravation or weight loss. He was initially diagnosed with acute severe pancreatitis. The patient received octreotide 0.1 mg subcutaneously every 8 hours for 3 days, accompanied by aggressive intravenous fluid replacement. The patient’s abdominal pain improved after treatment. In April 2023, the patient experienced recurrent left upper abdominal pain and sought treatment at a local hospital (treatment details were unknown). Blood amylase (AMY) level was 216 U/L (normal range: 35–135 U/L, only mildly elevated) and lipase (LPS) level was 63 U/L (normal range: 0–67 U/L). For further diagnosis and treatment, the patient visited the Hematology Clinic of Guangxi Zhuang Autonomous Region People’s Hospital 3 days later. He also reported pain in the proximal phalangeal joint of his left middle finger without any triggering cause, for which he rated a three on the visual analog scale. The pain was not related to rest or activity, and there was no swelling of the joint, or morning stiffness. He had dry eyes and a dry mouth for 6 months, no difficulty eating solid food, and experienced intermittent abdominal pain and diarrhea, without recurrent fever. He was preliminarily diagnosed with recurrent pancreatitis and primary Sjögren’s syndrome. We found oocysts when we performed routine clinical stool testing, and further specimen analyses using modified antacid staining and high-throughput 18S ribosomal RNA (rRNA) amplicon sequencing technology confirmed that the strain was Cryptosporidium spp. This study conformed to the Case Report (CARE) guidelines. ³ In accordance with the local institutional policies, ethical approval was not required for this case report, and all patient details have been deidentified.

Results

The patient’s medical records were as follows: (a) white blood cell count: 3.2 × 10⁹/L (normal range: 3.5–9.5 × 10⁹/L); (b) granulocyte count: 1.22 × 10⁹/L, 38.1% (normal range: 40%–75%); (c) eosinophil count: 0.06 × 10⁹/L with a percentage of 1.9% (normal range: 0.4%–8.0%).(d) Hemoglobin level: 158 g/L (normal range: 130–175 g/L); (e) platelet count: 145 × 10⁹/L (normal range: 125–350 × 10⁹/L); (f) blood AMY level: 106 U/L (normal range: 35–135 U/L); (g) LPS level: 57 U/L (normal range: 0–67 U/L); (h) antinuclear antibody with a cytosolic speckled pattern and a 1:100 titer; (i) anti–SSA60 antibody level: 368.66 RU/mL (normal range: 0–20 RU/mL); and (j) anti–Ro52 antibody level: 32.99 RU/mL (normal range: 0–20 RU/mL).

Considering his recurrent pancreatitis and primary Sjögren’s syndrome, he received symptomatic treatment. His stool occult blood tested positive using the immune colloidal gold method. Microscopic examination revealed oval oocysts measuring 4–8 μm in diameter (Figure 1(a)); they were smooth and had colorless walls. Under fluorescence microscopy, the oocysts appeared oval and emitted a bright, milky white to yellowish green fluorescence (Figure 1(b)). The specimens were verified using modified antacid staining. In the antacid-stained specimen, the oocysts appeared rose red, with a blue–green background (Figure 1(c)). We identified the phylum Apicomplexa (Novel_Apicomplexa_Class_1, Figure 2) within the kingdom Protista using high-throughput 18S rRNA amplicon sequencing technology (forward primer 528 F: 5′-GCGGTAATTCCAGCTCCAA-3′; reverse primer 706 R: 5′-AATCCRAGAATTTCACCTCT-3′). Sequencing was performed on the Illumina NovaSeq 6000 platform (Illumina, San Diego, CA) using a PE250 sequencing strategy and a sequencing depth of 100,000 tags. After quality control and removal of chimeric sequences, valid data were obtained. By comparing these data with the PR2/SILVA databases, a total of 157 high-quality amplicon sequence variants (ASVs) were identified, among which 131 ASVs were annotated to known taxonomic units. Combining molecular findings, morphological characteristics (acid-fast staining positive and an oocyst diameter of 4–8 µm), and clinical manifestations, we associated ASV119 with Cryptosporidium spp. and reported it as “Novel_Apicomplexa_Class_1 (sporozoite).” The patient was diagnosed with Cryptosporidium spp. infection. He was treated with spiramycin (0.96 g orally; two tablets each time, four times/day) to alleviate diarrhea symptoms and rehydrated with fluids to treat the symptoms during the course of treatment. The patient’s gastrointestinal symptoms, including diarrhea and abdominal distension, improved significantly. Two weeks later, the patient was re-examined, and showed good recovery, normal defecation, absence of gastrointestinal symptoms, improved joint pain, and absence of Cryptosporidium spp. oocysts in multiple stool samples.

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Figure 1.

(a) Stool microscopy reveals an oval oocyst, 4–8 μm in diameter (100× oil-immersion microscope image with 10 μm scale bar). (b) Observation under a fluorescence microscope. The oocysts are round and fluoresce in a bright, milky white to yellowish green color and (c) in the antacid-stained specimens, the oocysts are rose red with a blue–green background.

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Figure 2.

High-throughput 18S rRNA amplicon sequencing technology identification of the Novel_Apicomplexa_Class_1 (sporozoa). rRNA: ribosomal RNA.

Discussion

Cryptosporidium spp. infection can lead to cryptosporidiosis, a zoonotic protozoal disease for which watery diarrhea is the main clinical manifestation. ⁴ Diarrhea may be accompanied by symptoms of gastrointestinal tract infection, such as abdominal pain, nausea, and vomiting. Patients with normal immune function will present with gastrointestinal symptoms dominated by acute watery diarrhea, and the prognosis is generally good. However, those suffering from immunodeficiency (e.g. patients with acquired immunodeficiency syndrome (AIDS)) may experience persistent and massive diarrhea, and those with serious conditions can suffer from frequent diarrhea that is not effectively controlled, resulting in water–electrolyte disorders, dehydration, and even death. ⁵ Cryptosporidium spp. is a class of tiny intestinal parasites with strong resistance to ozone and chlorination disinfection. Disinfecting water using conventional chlorination in water treatment plants is essentially ineffective, and compared with other parasites, Cryptosporidium spp. is more likely to cause outbreaks in water sources. Controlling Cryptosporidium spp. water contamination is one of the most important measures for the prevention of cryptosporidiosis. ⁶

The diagnosis of Cryptosporidium spp. infection is mainly based on a pathogenetic examination. Clinically, the infection can be diagnosed by collecting fecal specimens from patients and searching for Cryptosporidium spp. oocysts under a microscope using a special staining method. In this case, the patient experienced pain in the proximal phalangeal joint of the left middle finger and recurrent pancreatitis. The clinical gastrointestinal symptoms were similar to those of abdominal pain, diarrhea, and weight loss caused by Cryptosporidium spp. infection. In addition, the patient’s symptoms of dry eyes and mouth were consistent with his symptoms of Sjögren’s syndrome. Also, the presence of Cryptosporidium spp. infection may not be prioritized in clinical practice, and the morphology and structure of the Cryptosporidium spp. oocysts can easily be missed during microscopic examination under wet slides. In this situation, errors in clinical treatment decisions are more likely to occur. If the cause of the disease is not accurately identified, patients will suffer from a recurrence of symptoms after symptomatic treatment, making clinical treatment difficult. This time, the elliptical oocysts were visible in stool under the microscope; the oocysts in the antacid-stained specimens were rose red, with a blue–green background. The ascospores in the oocysts were irregularly arranged, and the residual body was brown and granular. The specimen was identified as Novel_Apicomplexa_Class_1 (sporozoite) by high-throughput 18S rRNA amplicon sequencing technology, and the patient was finally diagnosed with Cryptosporidium spp. infection. The symptoms improved after 2 weeks of clinical treatment for cryptosporidiosis. Previously, Franklin et al. ⁷ reported a case involving a 39-year-old woman who presented with progressively worsening abdominal pain and nonbloody diarrhea and was ultimately diagnosed with appendicitis secondary to C. parvum infection. Such cases are currently extremely rare. The transmission of cryptosporidiosis occurs mainly through the fecal–oral pathway. The possible transmission paths are as follows: (a) humans to animals, (b) humans to humans, and (c) human environment (including water, food, and air sources) to humans. The infection is also caused by accidental ingestion of Cryptosporidium spp. oocysts.^8–10 A large number of oocysts were found in the patient’s stool. Oocysts can end up in the stool if they are orally ingested into the body via contaminated water, food, and other environmental factors. If gastrointestinal symptoms, such as watery diarrhea, abdominal pain, nausea, and vomiting, occur after a history of exposure (e.g. drinking unhygienic water or close contact with Cryptosporidium-infected persons), possible Cryptosporidium spp. infection should be considered. If diarrhea is frequent, patients may even experience severe dehydration or acidosis, particularly if they suffer from symptoms such as dry eyes, dry mouth, less urine, and restlessness. Patients with AIDS who are infected with Cryptosporidium spp. may experience frequent diarrhea in the form of rice slop, as many as dozens of times a day, and may respond poorly to treatment. These patients suffer from indigestion, weight loss, and, in severe cases, death, and infection with Cryptosporidium spp. may also result in respiratory or biliary infections in some patients, which would make their conditions even worse.^11,12

To prevent the contamination of food and drinking water with human stool, sick animals, and carrier worms, attention should be paid to stool management and personal hygiene. Furthermore, to protect people with immune deficiencies or low immunity, their immunity should be enhanced, and contact with patients and diseased animals should be avoided. Anyone who comes into contact with patients and diseased animals should wash their hands and disinfect them in a timely manner. If gastrointestinal symptoms occur after a history of exposure, possible Cryptosporidium spp. infection should be considered.

Conclusion

After humans are infected with Cryptosporidium spp., the onset of the disease is often insidious, and its clinical manifestations can resemble those of various diseases, such as pancreatitis or Sjögren’s syndrome, making early clinical detection difficult and frequently leading to missed diagnoses. Clinicians should enhance their understanding of cryptosporidiosis and be open minded when assessing patients. It is essential to thoroughly examine patient history and perform necessary laboratory tests to reduce the rates of missed and misdiagnosed cases.

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