Communicable diseases remain a frequent cause of illness in the human population. Viruses, bacteria and fungi commonly pass from one person to another through direct contact or contamination of inanimate objects or food. Hand washing and adequate personal hygiene practices can help prevent the spread of many communicable diseases.
Head Colds
More than 200 known viruses circulating in the human population cause approximately 1 billion head colds each year in the United States, reports the National Institute of Allergy and Infectious Diseases. The illness passes from one person to another through airborne droplets and nasal secretions.
Viral Pharyngitis
Viral pharyngitis, or a sore throat, is a common communicable disease among children and adults. Virus particles pass from one person to another through the oral and nasal secretions. The American Academy of Family Physicians recommends hand washing and covering the mouth when coughing or sneezing to prevent the spread of viral pharyngitis.
Infectious Conjunctivitis
Various viruses and bacteria can cause infectious conjunctivitis, also known as pink eye, reports the patient information website All About Vision. Rubbing the infected eye and touching an inanimate surface leaves a reservoir of infectious particles with which another person can come into contact.
Chest Cold
Viruses account for the overwhelming majority of chest colds, also known as acute bronchitis. The illness passes from one person to another through droplets produced by coughing or contamination of inanimate surfaces, notes FamilyDoctor.org. Covering a cough with a tissue or coughing into one's sleeve can help prevent the spread of chest colds.
Stomach Flu
The stomach flu, or viral gastroenteritis, is a highly contagious illness caused by several viruses, including norovirus and rotavirus, reports the Centers for Disease Control and Prevention. Contamination of the hands with virus particles from the stool or emesis of an infected person serves as the primary route of transmission.
Hand, Foot and Mouth Disease
Hand, foot and mouth disease is a communicable viral illness commonly caused by coxsackievirus A16, according to the CDC. Mouth sores, fever and a blistering rash typically occur with the illness. Disease transmission occurs via contact with the stool or nasal or oral secretions from an infected person.
Ringworm
Ringworm is a fungal infection of the skin on the body, scalp, groin or feet. Fungal infections of the feet and groin are commonly known as athlete's foot and jock itch, respectively. These infections pass from person to person through direct skin contact or an intermediate inanimate surface, reports MedlinePlus.
Chlamydia
Chlamydia is a prevalent sexually transmitted infection caused by the bacterium Chlamydia trachomatis. The CDC reports that the infection frequently proves asymptomatic, which contributes to a high rate of transmission in the population.
Gonorrhea
Approximately 700,000 people in the United States contract the sexually transmitted bacterial infection gonorrhea each year, according to the CDC. Gonorrhea remains a common cause of female infertility and ectopic pregnancy.
HIV/AIDS
HIV/AIDS is a chronic, life-threatening viral illness transmitted primarily through having sexual contact with an infected person or sharing injection drug equipment. As of July 2010, the CDC estimates that approximately 21 percent of Americans infected with HIV are unaware they have the virus.
