Signs are clinical manifestations of disease that are visible, including vomiting, diarrhea, coughing and sneezing, fever, petechiae (reddish streaks or marks on the skin or mucus membranes), changes in normal pigmentation such as jaundice and lesions.
The combination of signs and symptoms is called the disease syndrome.
Some diseases may go undetected since no signs or symptoms
are visible. Asymptomatic diseases,
such as Trichmonas vaginalis in males and occasionally Salmonella
typhi can go undetected, though they can be spread to others.
infections by viruses such as measles and bacteria such as S.
pyogenes may persist for many years and the infected individual may
become an unintentional carrier of the disease.