Tag: ova and parasite

Case History

A 41 year old African male presented to the ED with complaints of abdominal pain, weight loss, and decreased appetite over one month. He immigrated from Zimbabwe 10 years prior, and most recently visited 4 months ago. His past medical history is non-contributory. He was found to have microcytic anemia (Hgb 9.3 g/dL, MCV 77.0 fL), pneumonia, and focal small bowel dilation with thickening and inflammatory changes on abdominal CT.

Endoscopy revealed a large, villous, infiltrative mass in the third portion of the duodenum. On histologic examination of the duodenum biopsy, viable Schistosoma eggs were seen within the vessels in the lamina propria and associated with adenocarcinoma (Images 1 and 2). Schistosoma mansoni eggs were identified on stool ova and parasite exam (Image 3), and serology was positive for Schistosoma IgG antibody.

Discussion

Although this is not a common infection to encounter in the US, prevalence in endemic areas ranges from 30-100%. Infection occurs through contact with water contaminated with human feces; common circumstances are irrigation ditches as well as bathing and washing water.¹

Schistosomiasis may be an indolent infection in many immunocompetent hosts. Chronic infection requires a shift from inflammatory TH1 response to a modulatory TH2 response.² There is also evidence that Schistosoma infection may downregulate the immune response by inducing M2 differentiation of macrophages.³ These anti-inflammatory macrophages have been associated with a microenvironment favorable to malignancy. It has also been shown that S. mansoni is a risk factor for hepatocellular carcinoma (HCC) and colonic adenocarcinoma, possibly by altering p53 activation, initiation of chronic granulomatous response that blocks venules, increasing cell turnover, and promotion of ROS and RNOS production.⁴ Anti-idiotype antibodies produced in chronic infection may also down-regulate both specific and non-specific immune responses.⁵

This case is an unusual presentation in the US in that viable ova are typically not seen, and S. mansoni is more likely to involve the distal colon and liver rather than the small bowel. There is a known association between S. mansoni infection and HCC, and there are sporadic reports of association with tumors of the prostate, ovary, uterus, and cervix.^5,6 To our knowledge however, there are no other reported cases of duodenal adenocarcinoma with concurrent schistosomiasis.

References

1. Chai J and Jung B. Epidemiology of Trematode Infections: An Update. 2019. Adv Exp Med Biol. 1154:359-409.
2. Barsoum RS, et al. Human Schistosomiasis: Clinical Perspective: Review. 2013. Journal of Advanced Research. 4:433-44.
3. Hussaarts L, et al. Chronic helminth infection and helminth-derived antigens promote adipose tissue M2 macrophages and improve insulin sensitivity in obese mice. 2015. FASEB J. 29(7):3027-39.
4. El-Tonsy MM, et al. Schistosoma mansoni infection: Is it a risk factor for development of hepatocellular carcinoma? 2013. Acta Trop. 128(3):542-7.
5. Palumbo E. Association Between Schistosomiasis and Cancer. 2007. Infectious Diseases in Clinical Practice. 15(3):145-8.
6. Peterson MR and Weidner N. Gastrointestinal neoplasia associated with bowel parasitosis: real or imaginary? 2011. J Trop Med. 2011:234254.

-Daniel Welder, MD is a second year Clinical Pathology resident at UT Southwestern Medical Center in Dallas, Texas. He has interests in Hematopathology, Transfusion Medicine and dabbles in Microbiology.

-Dominick Cavuoti, DO is a Professor at UT Southwestern in the Department of Pathology. He is multifaceted and splits his time as the Medical Director of the Parkland Hospital Clinical Microbiology Laboratory and Parkland Cytology attending among other administrative and educational activities.

-Clare McCormick-Baw, MD, PhD is an Assistant Professor of Clinical Microbiology at UT Southwestern in Dallas, Texas. She has a passion for teaching about laboratory medicine in general and the best uses of the microbiology lab in particular.

Case History

The infectious disease service was consulted on an 81 year old female for persistent fevers. She initially presented a few weeks prior with cough & shortness of breath which was diagnosed as an acute chronic obstructive pulmonary disease (COPD) exacerbation for which she received levofloxacin and steroids. The patient continued to have a persistent cough and dysphagia after discharge. Her respiratory status and cough worsened and she was readmitted and intubated. Vancomycin, piperacillin/tazobactam and levofloxacin were started as well as fluconazole for suspected esophageal candidiasis. Her past medical history was significant for breast cancer, atrial fibrillation, and diabetes mellitus. Of note, patient was originally from Puerto Rico but moved to the United States 40 years ago and denied recent travel and any known tuberculosis exposures. She formerly worked in a deli packing cheeses. A bronchoscopy was performed and a brochoalveolar lavage (BAL) specimen as well as blood and stool specimens were submitted for bacterial culture and ova and parasite exam.

Laboratory Identification

The bronchoscopy revealed a bloody fluid admixed with clots which was clinically consistent with diffuse alveolar hemorrhage. The roundworms depicted above were identified in both the BAL and stool O&P exam. Based on the presence of the short buccal cavity and the prominent genital primordium and the absence of eggs, the identification of Strongyloides stercoralis was made. Given the large amount of larvae present in both the lungs and gastrointestinal tract, the patient was diagnosed with a strongyloidiasis hyperinfection.  

Discussion

Strongyloides stercoralis is classified as a nematode (roundworm) and is the cause of strongyloidiasis in humans. The helminth is found worldwide, especially in warm climates and underdeveloped countries, and is the cause of 30-100 million infections. Infection is due to fecal contamination of soil, where free-living forms are found, or water. Infective filariform larvae penetrate intact skin, particularly bare feet, resulting in infection. The free living cycle begins with the rhabditiform larvae passed through the stool develops into the infective filariform larvae or when the  rhabditiform larvae mature into free living adult male & female forms that mate and produce eggs which then hatch and become infective filariform larvae that can infect humans. The parasitic life cycle begins with the infective filariform larvae penetrates human skin. The worm is then either coughed up from the lungs and swallowed or migrates to the small intestine where eggs are laid and hatch.

Patients may present with gastrointestinal symptoms such as abdominal pain, bloating, and diarrhea, pulmonary symptoms like dry cough and throat irritation, or skin rashes along points of entry (feet, ankles). When the larvae are in the lung, Loeffler’s syndrome, characterized by pneumonia symptoms with coughing and wheezing, may develop due to an accumulation of eosinophils in response to the parasitic infection. In patients who are immunocompromised, the rhabditiform larvae can develop into the filariform larvae in the host and can directly penetrate the bowel mucosa or perianal skin resulting in autoinfection, dissemination throughout the body, and high parasite burden. Symptoms of hyperinfection include bloody diarrhea, bowel perforation, destruction of lung parenchyma with bloody sputum, meningitis, and septicemia. Hyperinfection most commonly occurs after steroid administration for asthma or COPD exacerbation, but can also be seen in those receiving chemotherapy or who have had organ transplants.  

In the laboratory, the diagnosis of S. stercoralis is most often made by an ova and parasite exam of the stool, duodenal fluid, sputum or BAL specimens (Image 1). Most commonly the rhabditiform larvae are present and are identified by the presence of a short buccal cavity and prominent genital primordium (Image 2). These two features are helpful in distinguishing S. stercoralis from hookworms (Ancylostoma spp. and Necator americanus) which have a longer buccal cavity and indistinct genital primordium. The eggs of these two nematodes are also very similar, although typically S. stercoralis eggs hatch before they are passed in stool specimens. S. stercoralis can also be visualized on H&E histology sections in the crypts of intestinal biopsies where the adult female measures up to 2.2 mm in length. Finally, serologic testing can be helpful when there is a high suspicion of disease in the face of multiple negative stool exams, but cannot distinguish between a current or past infection. Most patients do not remember a specific exposure and prevention includes wearing gloves and shoes when handling or walking on soil that may contain contaminated fecal material. Treatment options for an acute or chronic S. stercoralis include a short course of ivermectin or albendazole. In the case of disseminated infection, ivermectin should be given until stool and sputum exams are negative for 2 weeks. In the case of our patient, she was started on ivermectin, but succumbed to the disease due to extensive pulmonary hemorrhage.   

-Jaswinder Kaur, MD, is a fourth year Anatomic and Clinical Pathology resident at the University of Mississippi Medical Center. 

-Lisa Stempak, MD, is an Assistant Professor of Pathology at the University of Mississippi Medical Center in Jackson, MS. She is certified by the American Board of Pathology in Anatomic and Clinical Pathology as well as Medical Microbiology. She is the Director of Clinical Pathology as well as the Microbiology and Serology Laboratories. Her interests include infectious disease histology, process and quality improvement, and resident education.

Case History

A twenty-four year-old male Kenyan refugee had been in the United States for about a month when he received a mandatory health screen for infectious diseases. He had no complaints and stated that overall, he was generally healthy. Physical exam was significant only for bilateral red conjunctiva. He stated at times his eyes get irritated and have since birth. As part of routine work-up, an ova and parasite stool exam was ordered. Organisms were detected as seen in Image 1.

 

Discussion

The patient’s stool examination showed Giardia cysts. Two nuclei are visible in the figure above with centrally located karyosomes. Also visible are the intracytoplasmic fibrils, seen as a darker purple area.

Giardia is a flagellated protozoan that causes giardiasis, a diarrheal illness. It is the most commonly diagnosed intestinal parasitic disease in the United States. It is known as Giardia intestinalis, Giardia lamblia, or Giardia duodenalis. The most common mode of transmission is drinking water contaminated with feces from infected mammals (1).

Symptoms vary and can last 1 week to years if untreated (2). Typical symptoms of giardia are “greasy, foul-smelling, frothy stools that float.” Interestingly, less common symptoms can be itchy skin, hives, eye and joint swelling (3). Retinal arteritis and iridocyclitis has been noted as well (4). It is possible that this patient’s eye irritation is due to a chronic giardiasis infection. Common treatment is usually with an antibiotic/antiparasitic drug like metronidazole (Flagyl).

Diagnosis of Giardia can be made by demonstrating the pear shaped trophozoites and/or ovoid cysts in feces. A key identifier for this parasite is the presence of the two to four nuclei with a central karyosome and intracytoplasmic fibrils that make the parasite look like a face under the microscope. However, because Giardia is excreted intermittently, it is recommended to sample three stool specimens on separate days (5). Due to problems in concentrating the organism for identification on a trichrome stain, a fecal immunoassay is available that is more sensitive and specific (5).

References

1. https://www.cdc.gov/parasites/giardia/index.html
2. Robertson LJ, Hanevik K, Escobedo AA, Mørch K, Langeland N. Giardiasis–why do the symptoms sometimes never stop?. Trends Parasitol. 2010;26(2):75-82.
3. https://www.cdc.gov/parasites/giardia/illness.html#seven
4. Wolfe MS. Giardiasis.[PDF – 8 pages] Clin Microbiol Rev. 1992;5(1):93-100
5. https://www.cdc.gov/parasites/giardia/diagnosis.html

 

-Angela Theiss is a pathology resident at the University of Vermont Medical Center.

-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Associate Professor at the University of Vermont.