Vaccines
People of all ages should stay current on their vaccinations. The World Health Organization indexes vaccine recommendations for countries around the world. Specific information about U.S. standard and travel vaccines, as well as precautions and contraindications to vaccination, are available from the Centers for Disease Control and Prevention. The U.S. vaccination schedule is established by the Advisory Committee on Immunization Practices and endorsed by the American Academy of Pediatrics, the American Academy of Family Physicians, and the American College of Physicians.
In addition to the links below, for further information we recommend the American Academy of Pediatrics (AAP), the University of Pennsylvania Vaccine Ethics Project, and PATH.
Anthrax
| Infectious Agent: | Bacillus anthracis |
| Mode of Transmission: |
Animals are the natural reservoir; bacterial spores can live in soil or in animal products such as wool. |
| Clinical Manifestations: |
Cutaneous anthrax causes painless blistering and ulceration. Gastrointestinal anthrax causes nausea, loss of appetite, bloody diarrhea, fever, and stomach pain. Inhalational anthrax causes sore throat, fever, muscle aches, cough, and other cold-like symptoms. |
| Outcomes: | Skin infections are treatable, but infections of the respiratory or digestive tracts are often fatal. |
| More Information: |
CDC, IAC, VEC, NNii |
Bacterial Meningitis
| Infectious Agent: | Vaccines are available against the major causes of bacterial meningitis: Haemophilus influenzae type b (Hib); Neisseria meningitidis serogroups A, C, W-135, and Y; and the most pathogenic serotypes of Streptococcus pneumoniae (pneumococcus). |
| Mode of Transmission: |
Exposure to respiratory secretions of infected persons via coughing or sneezing. |
| Clinical Manifestations: |
Meningitis is characterized by sudden fever, stiff neck or back, vomiting, and lethargy. All three bacteria can also cause sepsis (blood infection) and pneumonia; in addition, Hib can cause epiglottitis and serious skin infections. |
| Outcomes: | Hib meningitis is fatal in about 5% of patients and causes brain damage in 10-30% of survivors. The fatality rate for N. meningitidis is about 10%; many survivors suffer long-term sequelae, including loss of limbs. About 30% of those with pneumococcal meningitis die of the disease. |
| More Information: |
Hib: WHO, CDC, IAC, VEC, NNii N. meningitidis: WHO, CDC, IAC, VEC, NNii S. pneumoniae: WHO, CDC, IAC (children), IAC (adults), VEC, NNii |
Cholera
| Infectious Agent: | Vibrio cholerae (a bacterium) |
| Mode of Transmission: | Food or water contaminated with feces of infected persons. |
| Clinical Manifestations: |
Diarrhea, vomiting, leg cramps. |
| Outcomes: | Some strains produce only mild diarrhea, but others can cause death within hours if untreated. |
| More Information: |
CDC, VEC |
Diphtheria
| Infectious Agent: | Corynebacterium diphtheriae |
| Mode of Transmission: |
Exposure to respiratory secretions of an infected person via coughing or sneezing |
| Clinical Manifestations: |
Sore throat, fever; may progress to airway obstruction and coma |
| Outcomes: | Airway obstruction may result in coma or death. Diphtheria toxin can also cause myocarditis or neuropathy. |
| More Information: |
WHO, CDC, IAC, VEC, NNii |
Hepatitis A
| Infectious Agent: | Hepatitis A virus |
| Mode of Transmission: |
Ingestion of infected feces, usually facilitated by contaminated food or water. |
| Clinical Manifestations: |
Fever, malaise, loss of appetite, jaundice, nausea. Adults are more severely affected than children, whose infections may be asymptomatic. |
| Outcomes: | Illness may persist for weeks or months, but fatalities are unusual. |
| More Information: |
WHO, CDC, IAC, VEC, NNii |
Hepatitis B
| Infectious Agent: | Hepatitis B virus |
| Mode of Transmission: |
Exposure to blood, saliva, amniotic fluid, or other body tissues or fluids |
| Clinical Manifestations: |
Loss of appetite, vague abdominal discomfort, nausea, vomiting, rash, and jaundice. Most often asymptomatic at first, especially in children. |
| Outcomes: | About 1% of cases are fatal. Most infants who acquire the virus via childbirth will be chronically infected and have a 15-25% chance of premature death from cirrhosis or liver cancer. Pregnant women are at increased risk of fulminant disease. |
| More Information: |
WHO, CDC, IAC, VEC, NNii |
Herpes Zoster (Shingles)
Human Papillomavirus (HPV)
| Infectious Agent: | Human papillomavirus |
| Mode of Transmission: |
Direct contact |
| Clinical Manifestations: |
Warts on infected tissue |
| Outcomes: | A few of the many strains of human papillomavirus can develop into cancer of the cervix or other sites which are exposed to the virus. |
| More Information: |
WHO, CDC, IAC, VEC, NNii |
Influenza
| Infectious Agent: | Influenza virus |
| Mode of Transmission: |
Predominantly airborne |
| Clinical Manifestations: |
Sudden onset of fever, headache, fatigue, and cold symptoms |
| Outcomes: | Fatality rate is generally low and concentrated among the elderly and those with immunosuppression, but novel strains can display different patterns. |
| More Information: |
WHO, CDC, IAC, VEC, NNii |
Japanese Encephalitis
| Infectious Agent: | Japanese encephalitis virus |
| Mode of Transmission: |
Mosquitoes and other arthropods |
| Clinical Manifestations: |
Encephalitis is characterized by fever, headache, stiff neck, nausea, vomiting |
| Outcomes: | Severity varies greatly; infected infants are the most likely to experience neurological sequelae. |
| More Information: |
CDC, VEC |
Measles
| Infectious Agent: | Measles virus |
| Mode of Transmission: |
Airborne droplets or direct contact |
| Clinical Manifestations: |
Rash, high fever, cough, runny nose, red and watery eyes |
| Outcomes: | Complications may include pneumonia, diarrhea, encephalitis, and severe skin infections. Fatalities are rare in the developed world, but in Africa, measles kills nearly half a million children annually. |
| More Information: |
WHO, CDC, IAC, VEC, NNii |
Mumps
| Infectious Agent: | Mumps virus |
| Mode of Transmission: |
Airborne or by direct contact |
| Clinical Manifestations: |
Fever, headache, tiredness, swelling of parotid salivary gland |
| Outcomes: | Complications include meningitis and loss of hearing; postpubertal males may experience orchitis and, rarely, subsequent sterility. Mumps is a reported risk factor for testicular cancer. |
| More Information: |
WHO, CDC, IAC, VEC, NNii |
Pertussis (Whooping Cough)
| Infectious Agent: | Bordetella pertussis, a bacterium |
| Mode of Transmission: |
Airborne droplets of infected mucus |
| Clinical Manifestations: |
Paroxysmal cough of extended duration – several weeks is common. Coughing may be severe enough to induce vomiting, cyanosis, or loss of consciousness. |
| Outcomes: | Most pertussis deaths are in infants under 6 months. |
| More Information: |
WHO, CDC, IAC, VEC, NNii |
Plague
| Infectious Agent: | Yersinia pestis, a bacterium |
| Mode of Transmission: |
Bites from fleas usually carried into homes by rodents; cats and rabbits can also serve as vectors. Pneumonic plague is droplet-transmissible from person to person. |
| Clinical Manifestations: |
Depending on site of infection, illness manifests as bubonic (lymph nodes), pneumonic, or pharyngeal plague. |
| Outcomes: | Any of the forms can progress to septicemic plague, which is fatal if untreated. |
| More Information: |
CDC |
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Poliomyelitis
| Infectious Agent: | Poliovirus |
| Mode of Transmission: |
Primarily person-to-person via exposure to feces. |
| Clinical Manifestations: |
Initial infection may be inapparent or cause mild fever, headache, nausea, and vomiting. Infection that spreads to the nervous system causes paralytic poliomyelitis – varying degrees of temporary or permanent paralysis. |
| Outcomes: | Paralytic poliomyelitis can be fatal. Survivors may experience post-polio syndrome later in life, with muscle weakness and pain. |
| More Information: |
WHO, CDC, IAC, VEC, NNii |
Q Fever
| Infectious Agent: | Coxiella burnetii, a bacterium |
| Mode of Transmission: |
Direct contact with infected sheep, cattle, goats, or other domestic and wild animals; organism can also travel long distances through the air. |
| Clinical Manifestations: |
Chills, headache, general malaise |
| Outcomes: | Infection may become chronic, mainly affecting the endocardium, but is rarely fatal. |
| More Information: |
CDC |
Rabies
| Infectious Agent: | Rabies virus |
| Mode of Transmission: |
Bites from various canine species, skunks, raccoons, bats, and other animals |
| Clinical Manifestations: |
Headache, fever, and malaise, progressing to hydrophobia, delirium, and convulsions |
| Outcomes: | Encephalomyelitis which is almost always fatal if untreated; vaccine is effective if given after exposure but before onset of symptoms. |
| More Information: |
CDC, IAC, VEC, NNii |
Rotaviral Gastroenteritis
| Infectious Agent: | Rotavirus |
| Mode of Transmission: |
Fecal-oral route; virus can persist for long periods on hard surfaces or in water. |
| Clinical Manifestations: |
Fever, vomiting, diarrhea |
| Outcomes: | Can cause fatal dehydration, particularly in infants; responsible for several hundred thousand deaths annually in the developing world. |
| More Information: |
WHO, CDC, IAC, VEC, NNii |
Rubella
| Infectious Agent: | Rubella virus |
| Mode of Transmission: |
Exposure to nose and throat secretions of an infected person, or to the urine of an infant with congenital rubella syndrome |
| Clinical Manifestations: |
Mild rash; many cases are subclinical |
| Outcomes: | Infection during the first trimester of pregnancy often leads to congenital rubella syndrome, which causes malformations of major fetal organ systems or intrauterine death. |
| More Information: |
WHO, CDC, IAC, VEC, NNii |
Smallpox
| Infectious Agent: | Variola virus |
| Mode of Transmission: |
Eradicated from natural circulation in 1979, but laboratory specimens still exist. Transmitted from person to person through direct contact or by exposure to respiratory secretions. |
| Clinical Manifestations: |
Fever, malaise, infective rash with pustules on the skin |
| Outcomes: | Variola major strain was markedly more lethal than variola minor |
| More Information: |
CDC, IAC, NNii |
Tetanus
| Infectious Agent: | Clostridium tetani |
| Mode of Transmission: |
Introduction of the bacterium into a puncture wound or, less commonly, through injection of contaminated street drugs or unhygienic surgical practices. |
| Clinical Manifestations: |
The toxin secreted by the bacterium causes painful, progressively more severe muscular spasms |
| Outcomes: | Most likely to be fatal in the very young and old |
| More Information: |
WHO (neonatal), WHO (general), CDC, IAC, VEC, NNii |
Tuberculosis
| Infectious Agent: | Mycobacterium tuberculosis |
| Mode of Transmission: |
Airborne droplets. Bacillus Calmette-Guerin (BCG) vaccine can prevent severe manifestations of TB in infants and young children but does not affect transmission of the disease. |
| Clinical Manifestations: |
Initial infection is usually asymptomatic, but leads to active disease in about 10% of those infected; infants and immunosuppressed individuals are at elevated risk. Disease is primarily pulmonary but can also affect the lymph nodes, pericardium, and other sites. |
| Outcomes: | About 65% of pulmonary cases are fatal within 5 years if not treated. |
| More Information: |
WHO, CDC, VEC, NNii |
Typhoid Fever
| Infectious Agent: | Salmonella typhi |
| Mode of Transmission: |
Exposure to food or water contaminated with feces or urine of infected persons |
| Clinical Manifestations: |
Fever, headache, bradycardia, skin markings, digestive disturbance |
| Outcomes: | Severe cases may be fatal if untreated; about 500,000 deaths annually, mainly in the developing world. |
| More Information: |
CDC, VEC, NNii |
Varicella (Chickenpox)
| Infectious Agent: | Varicella-zoster virus |
| Mode of Transmission: |
Direct or indirect contact with the respiratory fluids of an infected person or with vesicular fluid from a varicella lesion. |
| Clinical Manifestations: |
Blistered skin; sometimes fever and a generally unwell feeling |
| Outcomes: | Most lethal for neonates and adults; can cause birth defects when it affects pregnant women. Long-term latent infection can reappear as herpes zoster (shingles). |
| More Information: |
WHO, CDC, IAC, VEC, NNii |
Yellow Fever
| Infectious Agent: | Yellow fever virus |
| Mode of Transmission: |
Person to person via mosquito vector |
| Clinical Manifestations: |
Mild fever, headache, jaundice, vomiting; some cases appear to remit and then progress to a phase that includes bleeding from the nose, gums, and gastrointestinal tract. |
| Outcomes: | About 5% fatal |
| More Information: |
WHO, CDC, VEC, NNii |