Communicable diseases are caused by pathogens passed from one human to another. Pathogens are viral, bacterial, parasitic and fungal. Methods of transmission include mucus, blood, breath, saliva and sexual contact. Contaminated surfaces, such as doorknobs, counter tops and playground equipment, provide a medium for passing disease from one human to another.
The National Institute of Allergy and Infectious Diseases states that as of 2007, Americans have an estimated 1 billion colds each year. The age group most susceptible to repeated colds is children. People older than 60 average less than one cold a year. The common cold is a viral infection.
Viral gastroenteritis is a highly contagious disease spread by contact, such as sharing food or eating and drinking from contaminated utensils. Depending on the specific virus, gastroenteritis lasts from one to two days or up to 10 days. Two known causes of viral gastroenteritis are rotavirus and norovirus.
Strep throat is a communicable disease caused by group A streptococci bacteria. KidsHealth states that teens are particularly susceptible to strep throat during the school year. Strep throat bacteria spread easily by sneezing, coughing or shaking hands. A rapid strep test in the doctor's office will confirm whether the symptoms are because of strep throat or a viral sore throat.
Pink eye is a common name for a highly contagious form of bacterial or viral conjunctivitis. The virus that causes the common cold causes viral pink eye. Staphylococcus or streptococcus cause bacterial pink eye. To reduce the chances for spreading pink eye, avoid touching the infected eye, wash your hands frequently and avoid reusing towels or washcloths in contact with the eye.
The Children's Hospital of Philadelphia states that fifth disease, a human parvovirus, is most common among children and spreads through direct contact with nasal and throat discharge. Exanthem, a skin rash or eruption, appears at onset of the disease. Fifth disease spreads easily because it is contagious before symptoms of the rash appear.
Gonorrhea, a sexually transmitted disease caused by the Neisseria gonorrhoeae bacterium, is a common infectious disease. The Centers for Disease Control and Prevention estimates more than 700,000 people acquire gonorrheal infections every year. Sexual activity is the primary method of spreading the disease.
Hepatitis is a viral infection of the liver. The three types of hepatitis are hepatitis A, hepatitis B and hepatitis C. The most prevalent of the three types worldwide is the hepatitis B virus, with about 350 million people infected in 2005. Hepatitis causes inflammation of the liver that can lead to life-threatening conditions, such as cirrhosis and liver failure.
Whooping cough, or pertussis, is a highly communicable disease that affects all ages. The symptoms of whooping cough include respiratory infection, runny nose, low-grade fever and a mild cough that progresses to an uncontrollable cough with a high-pitched whoop.
Rotavirus is a highly contagious infection that affects the gastrointestinal system of children. Symptoms include nausea, vomiting, fever and watery diarrhea. Rotavirus is a noted problem in daycare facilities. The virus spreads from the stool of infected individuals. Poor hand washing technique following toilet use easily spreads the rotavirus.
HIV (human immunodeficiency virus) causes AIDS (acquired immunodeficiency syndrome) in the late stages of infection. HIV is in the semen, vaginal fluid and blood of infected persons. Unprotected sex and shared needles or syringes with HIV or AIDS carriers are the main methods of disease transmission.