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Questions and Answers
Which of the following is caused by the measles morbillivirus?
Which of the following is caused by the measles morbillivirus?
What characterizes an exanthem?
What characterizes an exanthem?
Which of the following is a known aetiological agent of rubella?
Which of the following is a known aetiological agent of rubella?
Which condition is primarily associated with Staphylococcus infections?
Which condition is primarily associated with Staphylococcus infections?
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What type of rash is typically characterized by raised spots?
What type of rash is typically characterized by raised spots?
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Which vaccine is available for preventing rubella?
Which vaccine is available for preventing rubella?
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Which of the following is NOT a common characteristic of viral exanthems?
Which of the following is NOT a common characteristic of viral exanthems?
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Chickenpox is primarily caused by which virus?
Chickenpox is primarily caused by which virus?
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What is the causative agent of scrub typhus?
What is the causative agent of scrub typhus?
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What is one of the common early symptoms of scrub typhus?
What is one of the common early symptoms of scrub typhus?
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What type of sample is usually used for serological diagnosis of scrub typhus?
What type of sample is usually used for serological diagnosis of scrub typhus?
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Which of the following is not a preventive measure for scrub typhus?
Which of the following is not a preventive measure for scrub typhus?
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Which treatment is commonly used for scrub typhus?
Which treatment is commonly used for scrub typhus?
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What is the incubation period for chickenpox?
What is the incubation period for chickenpox?
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Which virus is responsible for measles?
Which virus is responsible for measles?
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Which of the following is NOT a complication associated with measles?
Which of the following is NOT a complication associated with measles?
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What type of rash is commonly associated with chickenpox?
What type of rash is commonly associated with chickenpox?
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What is a notable feature of the rubella rash?
What is a notable feature of the rubella rash?
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Which of the following best describes the virulence factor of the Group A Streptococci that helps resist phagocytosis?
Which of the following best describes the virulence factor of the Group A Streptococci that helps resist phagocytosis?
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What is the primary method of laboratory diagnosis for Group A streptococcal infections?
What is the primary method of laboratory diagnosis for Group A streptococcal infections?
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What initial symptoms are commonly associated with streptococcal toxic shock syndrome (STSS)?
What initial symptoms are commonly associated with streptococcal toxic shock syndrome (STSS)?
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Which chemoprophylaxis is first-line for meningococcal sepsis?
Which chemoprophylaxis is first-line for meningococcal sepsis?
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Which is the characteristic rash of Neisseria meningitidis infection?
Which is the characteristic rash of Neisseria meningitidis infection?
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Study Notes
Exanthems
- Exanthem is a widespread rash, symmetric, and red with macules or papules.
- Exanthems are caused by viral or bacterial infections.
- Exanthems can be caused by drugs, toxins, or autoimmune diseases.
Viral Exanthems
- Very infectious.
- More common in childhood.
- Can cause outbreaks/ epidemics.
- High morbidity.
- Adults get more severe disease.
Measles (Rubeola)
- Caused by the measles morbillivirus.
- Incubation period 10-21 days.
- Prodrome of runny nose, fever, cough.
- Koplik spots: tiny spots in oral mucosa red with blue-white centers.
- Complications like acute otitis media, viral pneumonia, myocarditis, pericarditis, encephalitis (0.1% of cases).
German Measles (Rubella)
- Caused by the rubella virus.
- Symptoms are generally low-grade fever, enlarged lymph nodes, and an itchy rash.
- Rash appears fine and pink on the face, trunk, arms, and legs.
- Rubella is less infectious and severe than measles.
- Lacks post-measles staining.
Erythema Infectiosum
- Caused by parvovirus B19.
- Incubation period 4-14 days.
- Affects preschool and school-age children.
- Prodrome: 1-3 days or absent.
- "Slapped cheek" appearance with circumoral pallor.
- Lacy reticular pattern or fading rash.
- Contagious up to the presence of rash.
- Spread via respiratory route.
Chickenpox (Varicella)
- Caused by a herpes virus.
- Itchy, fluid-filled blisters that eventually scab over.
- Starts on the chest, back, and face, then spreads to the rest of the body.
- Palms and soles are spared.
- Successive crops of blisters.
- Incubation period 10-21 days.
- Fever with the onset of the rash.
Group A Streptococci
- Erythrogenic toxins cause rash in scarlet fever.
- Haemolysins:
- Streptolysin O (Oxygen labile - antigenic).
- Streptolysin S (Oxygen stable - haemolysis).
- DNAses: hydrolyze nucleic acid.
- C5a peptidase: inactivates human C5a.
- Pyrogenic exotoxins: SPE-A, SPE-B, SPE-C.
- Streptokinase: spreads infection.
- Hyaluronidase: degrades hyaluronic acid.
- M protein: resists phagocytosis by PMNL.
- F protein: binds to host fibronectin and mediates internalization of bacteria into host cells.
- Hyaluronic acid capsule: antiphagocytic.
Meningococcal Sepsis
- Caused by Neisseria meningitidis.
- Gram-negative diplococci.
- Common serotypes: A, B, C, W135, Y.
- Rapidly fatal.
- Rash: maculopapular, non-purulent erythematous lesions on extremities sparing the body.
- Petechial rash in 75% of cases.
Rickettsial Infections
- Rocky Mountain spotted fever: R. rickettsii, spread by ticks.
- Rickettsialpox: R. akari, spread by mites on wild rodents.
- Scrub typhus: Orientia tsutsugamushi, spread by larval mites.
- Epidemic typhus: R. prowazekii, spread by lice.
- Murine endemic typhus: R. typhi, spread by fleas.
Typhus
- Scrub typhus is caused by Orientia tsutsugamushi.
- Spread to people through bites of infected larval mites.
- Symptoms: fever, headache, body aches, rash.
- Common in Southeast Asia, Indonesia, China, Japan, India, and northern Australia.
- Treated with doxycycline.
Laboratory Diagnosis
- Rash may give a clinical diagnosis.
- Viruses can be isolated but are no longer commonly done.
- Serology: paired samples of IgM and IgG.
- Bacterial culture: blood cultures, throat swabs, vesicular fluid, CSF, pleural fluid, EDTA blood for PCR.
Treatment
- Symptomatic: hydration, antipyretics, antihistamines for itching.
- Rest, nutrition, isolation until infectivity ends.
- Chickenpox: aciclovir.
Prevention
- Vaccination available for varicella, measles, rubella, and meningococci.
- Typhus: no vaccine available.
- Due to long incubation periods, post-exposure prophylaxis with vaccination possible for measles and chickenpox.
- Know your local EPI schedule.
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Description
Test your knowledge on exanthems, including their causes, characteristics, and specific types like measles and rubella. This quiz covers the epidemiology, symptoms, and complications associated with these viral infections. Ideal for students studying infectious diseases.
