Question

Question 4 (2 points) Which of the following diseases could NOT be correctly described as follows? Viral infection of the upper respiratory tract leading to viremia, then skin rash (exanthem). None of the other four answers (All could be correctly described in this way) Measles (Rubeola) Scarlet fever Rubella OSmallpox

Answer 1

Correct answer: Scarlet fever

Scarlet fever is caused by bacteria and starts as a sore throat, skin rash which can lead to rheumatic fever. This bacteria is the same that gives strep throat (caused by Streptococcal bacteria) and if untreated can spread to the lungs, skin, kidney etc. The bacteria release a certain toxin that produces the skin rash like sunburn and reddish tongue. It spreads from person to person via droplets expelled via coughs or sneezes.

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All other mentioned options, which are Measles (Rubeola), Rubella, Smallpox are all caused by the virus and affect the upper respiratory tract. These can lead to viremia- a condition for the viruses present in the bloodstream. These later invade the host cell machinery and replicate extensively. These almost every time lead to the skin rash as one of their primary symptoms.

1) Measles (Rubeola): The measles virus (MeV) is a single-stranded RNA virus which causes the highly contagious disease measles, also known as rubeola. The infection is communicable and is spread by direct contact with secretions or inhalation of airborne droplets of infection via coughing or sneezing. The symptoms are generally high fever, conjunctivitis and sore throat which later leads to rashes on the face and spreads to the extremities.

2) Rubella: Rubella, or the German measles, is relatively milder which produces a rash like that of measles. Rubella causing microorganism is an enveloped RNA virus found in the respiratory tract. It is transmitted through direct contact via coughing or sneezing. This too begins with a facial rash that spreads to the extremities like legs, arms etc.

3) Smallpox: This disease is caused by the poxvirus known as variola and is transmitted by the inhalation of viral particles by the contaminated secretions or droplets. This disease is highly contagious and fatal. This virus starts infection in the lungs and invades the bloodstream accompanied by its infection in the skin, intestines, lungs, kidneys, and brain. This virus produces blisters in the skin cells which later turns into pus-filled pustular skin rash.