A child with a cold and cough but with all normal blood counts may have an acute respiratory infection caused by a viral infection or cough symptoms due to Mycoplasma or Mycobacterium tuberculosis infection. Colds, also known as acute upper respiratory infections, can cause babies to show symptoms of coughing. Acute upper respiratory infections are most often caused by viral infections, when blood counts can appear normal. If your baby is infected with Mycoplasma or Mycobacterium tuberculosis, he or she may also have a cough, and the blood count may be normal. The diagnosis of cold and cough does not only rely on blood tests, but also on other tests, such as antibody tests, if necessary, in order to treat the symptoms.