In your post at 0826 you said there were 48 cases of pertussis and now there are 35. Pertussis outbreaks occur across the country every year. Once infected the cough can persist for months.
The CDC estimates that there are epidemic outbreaks every 3-5 years. CDC - Pertussis: Outbreaks
Localized outbreaks of pertussis are not uncommon and occur throughout the year. Some examples of pertussis activity in the US include:
- In Washington, there have been 2,092 cases reported statewide through June 5, 2012, compared to 164 reported cases in 2011 during the same time period. There were 965 cases reported statewide in 2011 compared to 608 reported cases in 2010. Visit the Washington State Department of Health for the most recent information.
- In 2010, 9,143 cases of pertussis (including ten infant deaths) were reported throughout California. This is the most cases reported in 63 years when 9,394 cases were reported in 1947 and the highest incidence in 52 years when a rate of 26.0 cases/100,000 was reported in 1958. Previously, the peak was in 2005 when there were 3,182 cases reported. In 2011, disease activity was at relatively increased levels throughout the state. Visit the California Department of Public Health website for the most recent information.
The treatment is with antibiotics and a good cleaning. Outbreaks at middle and high schools
can occur as protection from childhood vaccines fades. In school outbreaks, prophylaxis is recommended for close classroom and team contacts — and the pertussis booster vaccine (Tdap) depending on age. Pertussis outbreaks in hospitals and other clinical settings can put infants and other patients at risk.
The Tdap is about 80% effective against infection in infants and children and about 70% effective in adults. It doesn't necessarily prevent infection but will produce a mild form.
CDC - Pertussis (Whooping Cough) homepage
Vaccines and Preventable Diseases:
Pertussis (Whooping Cough) Vaccination
Vaccines: VPD-VAC/Pertussis/main page
I hope this helps.