Texas Southern University Clinical Laboratory Science CLS 3 ✓ Solved

Texas Southern University Clinical Laboratory Science Clsc 369 Cas

Identify the parasite in the image provided, describe its microscopic characteristics including size and distinguishing features, based on the case and image provided.

Sample Paper For Above instruction

Diagnosis and Microscopic Characteristics of the Parasite in Case 1

In analyzing the case of a four-year-old child presenting with severe abdominal pain, the microscopic examination revealed a parasitic object measuring approximately 73 micrometers in length and 37 micrometers in width in stool samples. Based on these dimensions, morphological characteristics, and the context, the parasite identified is likely Entamoeba histolytica cysts or trophozoites, which are common causative agents of amoebiasis in children, especially presenting with intestinal symptoms.

Entamoeba histolytica is a protozoan parasite responsible for amoebic dysentery, which often presents with abdominal pain mimicking appendicitis, as in this case. The cyst form is typically about 12-20 micrometers in diameter, but during excystation, the trophozoite can reach larger sizes—up to 60 micrometers. The dimensions observed—73 by 37 micrometers—suggest the object could be a mature trophozoite with a slightly elongated shape, or possibly a stained cyst that has absorbed some stain, causing an apparent increase in size. Its distinguishing features include the presence of ingested red blood cells within the trophozoite cytoplasm, a characteristic nucleus with a small central karyosome, and vacuolated cytoplasm. These features are further confirmed in H&E-stained tissue sections, consistent with E. histolytica trophozoites infiltrating tissue.

The microscopic identification relies on size, shape, and internal features, including the presence of ingested erythrocytes—indicative of pathogenic trophozoites—setting it apart from nonpathogenic species like Entamoeba dispar. The low number of organisms in concentrated wet mounts supports a diagnosis of invasive amoebiasis rather than merely colonization or non-invasive forms.

Thus, considering the clinical presentation, histopathological evidence, and microscopic features described, the diagnosis for this case is Entamoeba histolytica.

Details such as size and morphological features—oval or round shape, size exceeding typical cyst dimensions, and the presence of ingested red blood cells—are essential criteria in this diagnosis.

References:

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For Case 2, the diagnosis is malaria caused by Plasmodium falciparum. Examination of the blood smear at 1000× magnification shows characteristic features such as the presence of infected erythrocytes containing prominent applique forms or crescent-shaped gametocytes typical of P. falciparum. Diagnostic criteria include the appearance of the parasite stages within the red blood cells, including ring forms, trophozoites, and gametocytes, as well as the high level of parasitemia, which correlates with severe symptoms like high fever and headaches.

The microscopic identification involves recognizing the ring-shaped trophozoites with applique or accole forms adhering to the erythrocyte membrane and crescent-shaped gametocytes, which are distinctive features for P. falciparum. The organism's size varies but generally is around 1-2 micrometers in diameter in the red blood cell. The staining with Wright-Giemsa highlights these features vividly, aiding differentiation from other Plasmodium species.

Infections with P. falciparum are associated with more severe clinical manifestations due to the parasite's ability to sequester in deep tissues, leading to complications like cerebral malaria. The patient's travel history to West Africa, where P. falciparum is endemic, supports this diagnosis. The identification of specific parasite stages in the blood smear confirms the diagnosis, guiding timely treatment with antimalarial drugs.

References

  • Preiser, P., et al. (2016). Malaria diagnosis: microscopy and rapid diagnostic tests. Expert Review of Molecular Diagnostics, 16(12), 1239-1244.
  • Haddad, D. (2014). Morphology of malaria parasites in blood films. Journal of Clinical Microbiology, 52(3), 879-885.
  • Suarez, J., et al. (2019). Diagnosing malaria: microscopy, rapid diagnostic tests, and molecular methods. Current Infectious Disease Reports, 21, 44.
  • Zumla, A., & McMichael, A. J. (2014). Malaria. In Medical Microbiology. Elsevier.
  • WHO. (2022). World Malaria Report 2022. World Health Organization.
  • Prakash, S., et al. (2018). Hematology of malaria: diagnostic challenges and recent advances. Blood Reviews, 32(1), 14-27.
  • Longo, D. L., & Fauci, A. S. (2012). Harrison's Principles of Internal Medicine. McGraw-Hill Education.
  • Moorthy, V. S., et al. (2020). Malaria vaccine development and its challenges. Nature Reviews Drug Discovery, 19(3), 181-202.
  • Health, WHO. (2019). Guidelines for the Treatment of Malaria. World Health Organization.
  • Barnett, S. F., & Brooks, J. M. (2015). Malaria: biology and clinical aspects. Infectious Disease Clinics of North America, 29(2), 393-408.

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