Pertussis, Pertussis

It derived its name from the "whoop" sound made from the inspiration of air after a cough. A similar, milder disease is caused by B. parapertussis.

Ninety percent of all cases occur in the Third World. Canada is the only rich, industrial nation in which pertussis is still commonplace, http://chealth.canoe.ca/channel_condition_info_details.asp?disease_id=217 though Australia saw a large increase in cases during a 2008/09 outbreak.

Pertussis is spread by contact with airborne discharges from the mucous membranes of infected people, who are most contagious during the catarrhal stage. Because the symptoms during the catarrhal stage are nonspecific, pertussis is usually not diagnosed until the appearance of the characteristic cough of the paroxysmal stage.

For most adults and adolescents, who often do not seek medical care until several weeks into their illness, serology is often used to determine whether antibody against pertussis toxin or another component of B. pertussis is present at high levels in the blood of the patient. By this stage they have been contagious for some weeks. Because of this, adults, who are not in great danger from pertussis, are increasingly being encouraged to be vaccinated.

Three macrolides (erythromycin, azithromycin and clarithromycin) are used in the U.S. for treatment of pertussis; trimethoprim-sulfamethoxazole is generally used when a macrolide is ineffective or is contraindicated. Close contacts who receive appropriate antibiotics ( chemoprophylaxis ) during the 721 day incubation period may be protected from developing symptomatic disease. Close contacts are defined as anyone coming into contact with the respiratory secretions of an infected person in the 21 days before or after the infected person's cough began.

The complete B. pertussis genome of 4,086,186 base pairs was sequenced in 2002.

Although Canada, France, the U.S. and Germany now have approved booster shots for adolescents, adults, or both, other countries adhere to the tradition of discontinuing pertussis vaccination after the age of seven, from concerns that there are side effects associated with the first available "whole-cell" pertussis immunizations that tended to increase with age. The whole-cell vaccine is still used in poor countries, because it is cheaper than the newer and safer acellular formulation.

As adolescent and adult cases surge, newborns are again at risk of exposure to pertussis circulating in adolescents or adults in the community before the infants' vaccinations can be completed.

The most serious side-effects of traditional "whole-cell" pertussis immunizations were neurological: and included seizures and hypotonic episodes.

The actual incidence was likely much higher. After vaccinations were introduced in the 1940s, incidence fell dramatically to less than 1 per 100,000 by 1970. Incidence rates have increased somewhat since 1980. Pertussis is the only vaccine-preventable disease that is associated with increasing deaths in the U.S. The number of deaths increased from 4 in 1996 to 17 in 2001, almost all of which were infants under one year.

Source: Wikipedia > Pertussis