Facts about common vaccines

By the time an American child is 12, most will have received up to 35 shots to protect against some 34 diseases. Public health officials say even though many of these diseases are now rare in the U.S., the viruses and bacteria that cause them are either still in common circulation or can be easily imported by travelers.

Here's a rundown on some of most dangerous childhood diseases and what shots are recommended to prevent them.

Diphtheria

Before vaccine: 175,00 cases a year

What is it? Bacterial infection that produces a toxin that can cause heart and nerve problems. Death rate of 10 to 20 percent.

Vaccine: DTP - 5 doses by age 6,

Hib -- haemophilus influenzae type b

Before vaccine: 20,000 cases a year.

What is it? Bacterial infection that can strike the brain, blood, lungs or throat, typically causing bacterial meningitis that kills or causes deafness, mental retardation.

Vaccine: Hib - 4 doses by 15 months.

Measles

Before vaccine: 500,000 cases a year, 450 deaths

What is it? Viral infection easily spread by sneezing, coughing. About 1 in 5 patients have complications including ear infections or pneumonia and in some cases can strike the lining of the brain.

Vaccine: MMR -- 2 doses at 12 months, 4-6 years.

Mumps

Before vaccine: 200,000 cases a year.

What is it? A viral infection that's usually mild in children, but can cause paralysis, seizures and deafness. Can cause severe reproductive system symptoms in adults.

Vaccine : MMR - 12 months and 4-6 years.

Pertussis

Before vaccine: 148,000 cases a year, 9,000 deaths.

What is it? Also called whooping cough, this bacterial infection can cause prolonged coughing spells that last for weeks, making it hard to breathe or even drink. Can also lead to brain damage, seizures, and mental retardation.

Vaccine: DTP -5 doses by age 6, booster shots every 10 years after than.

Polio

Before vaccine: About 20,000 cases a year. Believed eradicated from U.S., but still circulating in parts of the world.

What is it: Virus cause acute paralysis that can lead to permanent disability or death, loss of lung function, limb movement.

Vaccine: Polio -- 4 doses from 2 months to 4 -6 years.

Rubella

Before vaccine: 48,000 cases a year.

What is it? Also known as German measles, the viral infection is usually mild in children, but infection of women in first 3 months of pregnancy can cause heart defects, deafness and other health problems in their babies, as well as miscarriages and neonatal deaths.

Vaccine: MMR 12 months and 4 to 6 years.

Tetanus

Before vaccine: More than 1,300 cases a year.

What is it? Also called lockjaw, it is a severe, often fatal bacterial infection found in common soil and dust, waste of animals. It causes stiffness and muscle spasms, closing of throat. About 30 percent of infections result in death.

Vaccine: DTP - 5 doses by age 6, booster every 10 years

Web sites for additional information

U.S. Centers for Disease Control and Prevention-- www.cdc.gov/nvpo/

National Network for Immunization Information -- www.immmunizationinfo.org

American Academy of Pediatrics Childhood Immunization and Support Program: www.cispimmunize.org/

National Vaccine Information Center advocating informed consent and safety of vaccines, www.nvic.org

(Distributed by Scripps Howard News Service, http://www.scrippsnews.com)