Nokea
A child with diarrhea had stool microscopy revealing cysts with four nuclei. What is the most likely causative agent?
- A. Entamoeba histolytica
- B. Giardia lamblia
- C. Balantidium coli
- D. Trichomonas hominis
Correct Answer: A
Rationale: The correct answer is A: Entamoeba histolytica. This pathogen is known to cause amoebic dysentery, characterized by diarrhea with bloody or mucoid stools. The presence of cysts with four nuclei in the stool microscopy is a characteristic feature of Entamoeba histolytica. Other choices are incorrect because Giardia lamblia typically presents with binucleate cysts, Balantidium coli is a ciliated protozoan, and Trichomonas hominis is a non-pathogenic parasite found in the human intestine.
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Protozoan emerging and reemerging diseases generally belong to group:
- A. I
- B. II
- C. III
- D. IV
Correct Answer: A
Rationale: The correct answer is A because protozoan emerging and reemerging diseases fall under Group I according to the classification of infectious diseases by the Centers for Disease Control and Prevention (CDC). Group I includes diseases caused by newly identified or known infectious agents that have increased in incidence or geographic range. Choice B (Group II) includes diseases that have re-emerged due to antimicrobial resistance or lack of previous vaccination. Choice C (Group III) encompasses diseases that can be transmitted from animals to humans, and choice D (Group IV) includes diseases that are caused by re-introduction of eradicated pathogens.
Microscopic examination of dental plaque revealed unicellular organisms with two layers in their cytoplasm and wide pseudopodia. What is the likely causative agent?
- A. Entamoeba gingivalis
- B. Entamoeba histolytica
- C. Trichomonas tenax
- D. Lamblia intestinalis
Correct Answer: A
Rationale: Rationale:
1. Unicellular organisms with two layers in cytoplasm = Entamoeba gingivalis.
2. Wide pseudopodia = characteristic of Entamoeba genus.
3. Entamoeba histolytica causes amoebic dysentery, not dental plaque.
4. Trichomonas tenax causes periodontal disease, not dental plaque.
5. Lamblia intestinalis causes giardiasis, not related to dental plaque.
The human pinworm Enterobius vermicularis lives in the __________ of humans.
- A. duodenum
- B. ileum
- C. transverse colon
- D. rectum
Correct Answer: D
Rationale: The correct answer is D: rectum. Pinworms typically inhabit the rectum area in humans, where they lay their eggs. This is because the female pinworm migrates to the rectum at night to deposit her eggs near the anus. Other choices are incorrect because pinworms do not reside in the duodenum (A), ileum (B), or transverse colon (C) as their primary location is in the lower gastrointestinal tract near the anus.
Which type of RNA carries the genetic code for protein synthesis?
- A. mRNA
- B. tRNA
- C. rRNA
- D. snRNA
Correct Answer: A
Rationale: The correct answer is A: mRNA. mRNA carries the genetic code from the DNA in the cell nucleus to the ribosomes in the cytoplasm, where protein synthesis occurs. It serves as a template for protein synthesis by specifying the order of amino acids. tRNA (choice B) brings amino acids to the ribosome during protein synthesis. rRNA (choice C) is a structural component of ribosomes. snRNA (choice D) is involved in RNA processing and splicing, not protein synthesis. Therefore, choice A is correct as it directly carries the genetic code for protein synthesis.
Which are the most suitable materials for isolation of polio viruses?
- A. feces, duodenal and bile content
- B. blood, sputum, and urine
- C. only feces
- D. feces, nasopharyngeal swabs, and cerebrospinal fluid
Correct Answer: D
Rationale: The correct answer is D because polio viruses are primarily found in the gastrointestinal tract and respiratory secretions. Feces contain the highest concentration of the virus, while nasopharyngeal swabs and cerebrospinal fluid can also contain the virus. Blood, sputum, and urine do not typically contain high levels of polio virus. Choice A is incorrect as bile content is not a common site for polio virus isolation. Choice C is incorrect because only testing feces may not provide a comprehensive picture of the infection.