An analysis by researchers at the University of Michigan and the University of New Mexico shows that immunity to whooping cough lasts at least 30 years on average
An analysis by researchers at the University of Michigan and the University of New Mexico shows that immunity to whooping cough lasts at least 30 years on average, much longer than previously thought.
The research, by U-M professor of ecology and evolutionary biology Pejman Rohani and his former postdoctoral fellow Helen Wearing, who is now an assistant professor at the University of New Mexico, is scheduled to be published Oct. 23 in the open-access journal PLoS Pathogens.
Measles | Rubeola - Causes, Symptoms, Complications, Diagnosis, Treatment, Prevention
Measles is a viral infection with symptoms of fever,and rashes. Measles is prevented by vaccination and staying away from the infected individuals.
Measles is a viral infection with symptoms of fever,and rashes. Measles is prevented by vaccination and staying away from the infected individuals.
Several explanations have been proposed for the surprising increase in cases, and one leading idea is that the immunity enjoyed by vaccinated or previously exposed people is simply wearing off. It''s been documented that in some individuals immunity has waned over time, but the exact details of how long protection typically lasts and how its waning affects disease transmission have not been clear.
One way of exploring those questions would be to follow a group of people over time, tracking changes in their immune status. But that would be a large-scale, long-term undertaking, made all the more difficult by the fact that no clear-cut blood test exists for determining protection against pertussis infection.
Mumps - Causes - Symptoms - Diagnosis And Treatment - FAQs
Mumps is a contagious viral infection that typically causes a painful swelling of one or more of the salivary gland. Mumps most commonly occurs in children aged 2-12 years who have not been vaccinated against the disease. However, it can occur at any age. It was a common childhood disease before the development of the mumps vaccine (MMR vaccine).
Mumps is a contagious viral infection that typically causes a painful swelling of one or more of the salivary gland. Mumps most commonly occurs in children aged 2-12 years who have not been vaccinated against the disease. However, it can occur at any age. It was a common childhood disease before the development of the mumps vaccine (MMR vaccine).
The researchers constructed two models with different assumptions about what happens when a person whose immunity has lapsed is exposed to pertussis and how much that person contributes to transmission. Then they compared the models'' predictions to whooping cough incidence data from England and Wales from both the pre-vaccine era (1945-1957) and the vaccine era (1958-1972). In particular, Rohani and Wearing looked for matches in two key measures: the number of years between big outbreaks and the frequency of "extinctions"---periods of time when no whooping cough cases were reported in the population.
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Measles: No Measly Threat!
Measles has not been feared for a while due to its eradication, yet people could still be susceptible to an attack especially if they have not been vaccinated says a recent report.
Measles has not been feared for a while due to its eradication, yet people could still be susceptible to an attack especially if they have not been vaccinated says a recent report.
In addition, repeat infections appear to contribute relatively little to the transmission cycle, the researchers found. And when people whose immunity has waned are re-exposed to whooping cough, they rarely become infected. In fact, their immunity to the disease may be boosted by re-exposure, the study suggests.
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Measles Epidemic Kills More Than 200 Kids in North Nigerian City
A measles epidemic in the northern Nigerian city of Kano has killed over 200 children since the start of December 2007, health workers said Wednesday.
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Still, the researchers are cautious about drawing conclusions about current day vaccination practices from their study of historical data. "It''s worth pointing out that in the past 20 years or so, the nature of the vaccines that have been used has changed quite fundamentally," Rohani said. "The data we''re using are from a time when a whole-cell vaccine was in use; now an acellular vaccine, which stimulates a different part of the immune system, is typically used, especially in North America."
In new work, Rohani is using more recent data from the U.S., trying to uncover relevant factors associated with trends in whooping cough incidence.
"In the U.S. data, there''s a significant amount of variation among states," he said. "Some states show a strong resurgence in whooping cough, some show a decline, and some show no change. We''re looking at demographic variables like birth rates, and immigration profiles, population size and vaccination coverage, to see if we can discover key predictors."
In addition, Rohani is examining the historic data used in the PLoS Pathogens paper with different statistical methods, as well as developing models that incorporate explicit immunological information. Another project involves analyzing pertussis incidence data from Senegal, where detailed information on individuals'' vaccination, infection and reinfection histories has been kept on a population of 30,000 people.
"These are all ongoing and complementary studies," Rohani said, "that will shed further light on this important, but enigmatic infectious disease."
The researchers received funding from the National Institutes of Health; the RAPIDD program of the Science & Technology Directorate, Department of Homeland Security; and the Gates Foundation.
Source-Newswise
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