Diphtheria is NOT caused by infection of the upper respiratory tract.
Diphtheria is caused by the bacterium Corynebacterium diphtheriae, which produces a toxin that can cause severe respiratory illness and potentially life-threatening complications. Unlike the other options, scarlet fever, whooping cough, and streptococcal pharyngitis are all caused by infections of the upper respiratory tract.
Scarlet fever is caused by group A Streptococcus bacteria, which can also cause streptococcal pharyngitis. Whooping cough, also known as pertussis, is caused by the bacterium Bordetella pertussis. Streptococcal pharyngitis, also known as strep throat, is caused by group A Streptococcus bacteria.
It's important to note that some infections of the upper respiratory tract can also cause complications and spread to other parts of the body if left untreated. Therefore, it's important to seek medical attention if you experience symptoms such as fever, sore throat, coughing, or difficulty breathing.