by James Cole
It was reported recently that the number of pertussis (whooping cough) cases in Minnesota is now approaching 700. As Minnesota Public Radio reveals, this is more than double the number of cases reported earlier this month, and exceeds the total number of cases reported last year.
Minnesota is not alone in suffering a recent outbreak of this highly-contagious disease. As the CDC note on their website, there have been 1,484 cases reported in Washington to May 12th 2012, compared to 134 reported cases in 2011 during the same time period. The Washington State Department of Health website carries a note that in April the Secretary of Health declared a statewide pertussis epidemic. The CDC also has this on California:
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.
The increase in pertussis cases nationwide can be seen in the graphs on this CDC page. With regards pertussis incidence, the CDC writes that the overall incidence of pertussis “has been increasing steadily since 2007 and has now surpassed peak rates observed during 2004-2005”. The CDC also note that the highest reported rates of pertussis infection are in those most vulnerable: “Infants aged less than 1 year , who are at greatest risk for severe disease and death, continue to have the highest reported rate of pertussis.”
Regarding the severity of pertussis, this PDF contains information regarding the complications of pertussis, based on cases reported to the CDC 1997-2000: pneumonia in 5.2% of cases; seizures in 0.8%; encephalopathy in 0.1%; hospitalisation in 20%; and death in 0.2%.
The most common complication, and the cause of most pertussis-related deaths, is secondary bacterial pneumonia. Young infants are at highest risk for acquiring pertussis-associated complications. Data from 1997–2000 indicate that pneumonia occurred in 5.2% of all reported pertussis cases, and among 11.8% of infants younger than 6 months of age.
The CDC’s Pink Book also notes that neurologic complications of pertussis such as seizures and encephalopathy are more common among infants. In the period 2004-08, a total of 111 deaths from pertussis were reported to the CDC. Children 3 months of age or younger accounted for 92 (83%) of these deaths.
It’s not just Americans who should be concerned about this potentially deadly infectious disease. The HPA reported in April that there had been a continued increase in pertussis cases:
665* laboratory confirmed cases of whooping cough have been reported to the Health Protection Agency (HPA) in England and Wales between January and March 2012, compared to total of 1,040* cases across the whole of 2011.
The increase – continuing from the second half of 2011 - has been reported across all regions in England with some areas reporting clusters in schools, universities and healthcare settings.
Given what happened in England and Wales following the unfounded pertussis vaccine scaremongering in the 1970s (there were more than 200,000 extra notifications and 100 deaths in 1970s and 1980s), you would have thought that when it came to protecting children against an infectious disease with such serious complications we might know better. Sadly not.
James Cole blogs at Stuff And Nonsense