Question 41: Exanthema subitum is caused by -
- A. HIV
- B. HCV
- C. HPV
- D. HHV (Correct Answer)
Explanation: ***HHV***
- **Exanthema subitum**, also known as **roseola infantum**, is most commonly caused by **Human Herpesvirus 6 (HHV-6)** and sometimes **Human Herpesvirus 7 (HHV-7)**.
- It is characterized by high fever followed by a **maculopapular rash** once the fever subsides.
*HIV*
- **Human Immunodeficiency Virus (HIV)** causes **Acquired Immunodeficiency Syndrome (AIDS)**, leading to a weakened immune system.
- While HIV can cause various skin manifestations, **exanthema subitum** is not one of its primary or characteristic presentations.
*HCV*
- **Hepatitis C Virus (HCV)** primarily causes **hepatitis**, infecting the liver and potentially leading to chronic liver disease.
- HCV is not known to cause **exanthema subitum** or similar childhood exanthems.
*HPV*
- **Human Papillomavirus (HPV)** is responsible for **warts** and certain **cancers**, particularly cervical cancer.
- HPV does not cause **exanthema subitum**; its manifestations are typically localized to skin and mucous membranes as proliferative lesions.
Question 42: A child with fever with abdominal cramps & pus in stools, causative organism is ?
- A. EHEC
- B. ETEC
- C. EAEC (Correct Answer)
- D. EPEC
Explanation: ***EAEC (Enteroaggregative E. coli)***
- Among the E. coli strains listed, EAEC is the answer for this question, though **this is an atypical presentation**.
- EAEC classically causes **persistent watery diarrhea** (>14 days) in children, often with **low-grade fever** and **abdominal pain**.
- While EAEC primarily causes non-bloody diarrhea, it can occasionally produce **mucoid stools** with inflammatory cells due to mucosal inflammation from biofilm formation.
- **Note:** The classic organism for fever + cramps + pus in stools would be **Shigella**, **Campylobacter**, or **EIEC (Enteroinvasive E. coli)** - not listed here.
*EHEC (Enterohemorrhagic E. coli)*
- EHEC (O157:H7) causes **hemorrhagic colitis** with bloody diarrhea due to **Shiga toxins**.
- Can lead to **hemolytic uremic syndrome (HUS)** in children.
- Characterized by **blood** rather than pus in stools, distinguishing it from typical dysentery.
*ETEC (Enterotoxigenic E. coli)*
- Most common cause of **traveler's diarrhea** and watery diarrhea in developing countries.
- Produces **heat-labile (LT)** and **heat-stable (ST)** enterotoxins causing secretory diarrhea.
- Results in profuse **watery stools without inflammation, blood, or pus**.
*EPEC (Enteropathogenic E. coli)*
- Leading cause of infantile diarrhea in developing countries.
- Causes **attaching and effacing** lesions on intestinal mucosa.
- Results in **watery diarrhea without significant inflammatory cells or pus** in stools.