Minnesota health officials say an outbreak of whooping cough appears to be slowing in the state. In the past two weeks another 190 cases were confirmed. That’s nearly the same number of cases that were reported for just one week in mid-September. Officials say the drop in cases is a good sign, but there is still a lot of the disease circulating in Minnesota. Whooping cough, also known as pertussis, causes a persistent, severe cough that sometimes lasts for months. In total, Minnesota has confirmed more than 3,700 cases of the bacterial infection. That’s the highest number since the 1940s, before a vaccine was developed. Three-quarters of the new cases have occurred in vaccinated people.