Two weeks after a measles outbreak sickened at least 20 people in North Texas, the state is warning residents about another preventable disease: whooping cough.

Almost 2,000 Texans have contracted whooping cough this year - a number on track to pass the 50-year record of 3,358 cases in 2009, according to the state's department of health.

The contagious cough, named for its "whooping" sound, is caused by the bacterium Bordetella pertussis, which is spread through coughs and sneezes.

"This is extremely concerning," state infectious diseases medical officer Dr. Lisa Cornelius said in a statement. "If cases continue to be diagnosed at the current rate, we will see the most Texas cases since the 1950s."

A vaccine given in five doses during the first six years of life can lower the risk of whooping cough. But pertussis vaccination rate in Texas - about 94 percent - lags behind the national average, according to the U.S. Centers for Disease Control and Prevention.

"Pertussis is highly infectious and can cause serious complications, especially in babies, so people should take it seriously," Cornelius said.

Texas has already seen two pertussis-related deaths this year - both of them in infants who were too young to be vaccinated, according to the state's department of health.

The CDC recommends that all pregnant women get vaccinated against whooping cough between the 27th and 36th week of pregnancy, as antibodies passed from mother to baby can help protect against deadly infections in newborns. Other family members should also be vaccinated to guard the baby as its immune system develops, according to the agency.

While the CDC admits the whooping cough vaccine is "not perfect" (it protects an estimated seven out of 10 people who receive it), since the vaccine's arrival in the 1940s, the number of Americans infected and killed by the disease has dropped dramatically.

"Before pertussis vaccines became widely available in the 1940s, about 200,000 children got sick with it each year in the U.S.and about 9,000 died as a result of the infection," the CDC says on its website. "Now we see about 10,000-25,000 cases reported each year and, unfortunately, about 10-20 deaths."

The infection tends to be milder in teenagers and adults than in babies, and is typically treated with antibiotics, according to the CDC.

Click here for more information about whooping cough and its vaccine.