disease information
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Pertussis |
Pertussis (whooping cough) is an acute bacterial infection of the respiratory tract caused by Bordetella pertussis. The disease used to be one of the most common diseases among children and was associated with a high mortality rate prior to vaccine licensure. Disease incidence has declined in the US since the vaccine became widely available in the 1940’s. However, since the 1980’s, disease incidence has increased gradually.
Maine saw its largest increase in reported cases in 2004 followed closely by the incidence in 2006. The 2006 data included an outbreak that affected western, midcoast and southern counties.
All cases were designated as confirmed or probable pertussis using the CDC case definition. The average annual incidence rate for Maine 2000-2007 was 6.9 per 100,000.
A look at the time distribution of cases shows an increase of reported cases in the second half of 2006 and into early 2007. Cases were reported in all counties of Maine except Hancock and Oxford Counties in 2007. Twenty-eight percent of the cases were reported from Cumberland and York counties.
A comparison of Maine and US DTaP vaccination rates indicates that Maine’s population other than for a small segment completes the vaccination series necessary for protection against pertussis. The age distribution analysis indicates that the case numbers are highest amongst adolescents who, being exposed at school, have waning immunity. Children aged 5-9 years had the second highest number of cases in 2007. Many in this group may be the siblings of adolescents with pertussis. Transmission of pertussis to infants remains of great concern, as this group is most susceptible to complications of pertussis and to death from the disease.
In 2005 two tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine (Tdap) products were approved (Adacel ® (Sanoffi-Pasteur) for use in adults 11-64 years old and Boostrix ® (GlaxoSmithKline) for use in adolescents 10-18 years of age). In June 2005 ACIP recommended the use of a single Tdap dose instead of the usual Td toxoid booster vaccine for protection of adolescents 11-18. This recommendation, if implemented, should result in a reduction of the number adolescent cases of pertussis and also reduce the number of outbreaks that are seen each year.
Furthermore, timely reporting of suspected cases and the strict adherence to disease control recommendations would further reduce the incidence of the disease and the possible exposure of the most susceptible.
Source: Reportable Infectious Diseases in Maine: 2007 Summary