Whooping cough, or pertussis, is making a comeback around the United States. the annual number of cases nationwide has increased to around 13,000, compared with 1,500 cases per year in the 1980s.

A highly contagious respiratory tract infection, whooping cough used to be one of the most common childhood diseases and a major cause of childhood death. However, the number of cases declined after a vaccine was introduced in the 1940s, reaching an all-time low in the mid-1970s.

The recent increase in whooping cough cases has been mostly among infants under 6 months old who haven’t completed the full course of vaccinations. Teens and adults whose immunity has faded have also been affected.

Although the disease is rarely fatal, it still can be harmful to infants and small children.

After being infected with whooping cough, it takes three to 12 days for signs and symptoms to appear. Symptoms are usually mild at first and resemble those of a common cold — such as a runny nose, nasal congestion, sneezing, a low-grade fever and dry cough. After a week to 10 days, symptoms generally become more severe. Prolonged coughing attacks can occur, often ending with a high-pitched “whoop” sound during inhalation.

Children should receive a combination vaccine called DTaP — which protects against tetanus, whooping cough and diphtheria — at 2, 4 and 6 months, at 15-18 months and at 4-6 years. it also is recommended that adolescents be given a booster shot since immunity begins to wane about age 11.

Whooping cough can sometimes be diagnosed by listening to the cough. However, a nose or throat culture and test, a blood test to check for a high white blood cell count or a chest X-ray might be used to diagnose. Infants and small children are typically hospitalized for treatment, but older children and adults usually can manage the illness at home.

Treatment for whooping cough includes antibiotics that kill the bacteria causing whooping cough and help speed recovery. in addition, family members of patients might be given preventive antibiotics.

The best ways to prevent whooping cough are:

■ Make sure your children received the DTaP vaccine as recommended.

■ Make sure your middle school-age children receive a booster vaccine for whooping cough.

■ See a doctor if you or your child develops a severe cough that won’t go away.

■ Practice good hygiene. Wash your hands frequently, and cover your mouth when you cough.

■ be considerate of infants, and stay away from them if you have a cough.