Flu Helps Spread Pneumonia

April 15, 2011

Article Date: 12 Apr 2011 - 1:00 PDT

Bacteria that cause pneumonia and meningitis are only able to spread when

individuals are infected with flu, says a scientist reporting at the Society for

General Microbiology's Spring Conference in Harrogate. The work could have

implications for the management of influenza pandemics and could help reduce

incidence of pneumococcal infections in very young children, who are more

susceptible to disease.

Streptococcus pneumoniae normally lives harmlessly in the nasal passage. Up to

80% of young children carry the bacterium in their nose. It is already known

that if a colonized individual is infected with influenza virus, the bacterium

is more likely to spread to other parts of the body and may cause potentially

life-threatening infections such as pneumonia, sepsis or meningitis. Young

children, the elderly and the immunocompromised are most vulnerable to these

secondary bacterial infections. S. pneumoniae kills more than one million

children under the age of five each year.

Dr Dimitri Diavatopoulos from the Radboud University Nijmegen Medical Centre in

The Netherlands explains how infection with the flu virus is also necessary for

transmitting S. pneumoniae between individuals. His work has shown that in

infant mice, all mice had to be infected with flu for pneumococcal bacteria to

efficiently spread between them. Blocking influenza infection in these mice

effectively prevented the spread of the bacterium.

Viral infection is likely to encourage the spread of pneumonia through a

combination of factors, suggested Dr Diavatopoulos. " We think that the flu virus

increases the bacterial load in the nose of colonized individuals but also makes

uncolonized individuals more susceptible to pneumococcal infection by altering

host immunity. "

Dr Diavatopoulos believes that learning how viral infections affect not only the

development but also the spread of bacterial pathogens will be clinically

beneficial. " If we know that the flu virus - and potentially other respiratory

viruses - allows the transmission of S. pneumoniae, then targeting these viruses

may represent a novel therapeutic strategy to reduce pneumococcal diseases, " he

said. " During influenza pandemic planning, when a high proportion of the

population is infected with the virus, this is important. The findings are

particularly relevant to childcare centres as up to 80% of children are

asymptomatic carriers of S. pneumonia and are more vulnerable to developing

serious infections such as pneumonia or meningitis. "

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