Gert van der Hoek
In Memoriam - Editor, Senior Moderator
- Pneumonia is the leading cause of death in under-fives worldwide
- Vaccinating women against influenza in late-stage pregnancy reduces flu infection in infants under six months of age by more than 60%
Flu virus behind infant pneumonia in poor countries
Viral infection precedes an unexpectedly large proportion of childhood pneumonia cases.
Alison Abbott
Influenza may be a surprisingly important player in childhood pneumonia deaths in developing countries, a study has found 1. Pneumonia is the leading cause of death in under-fives worldwide — in poor countries more than one-fifth of childhood mortality is attributed to the disease.
The study, led by Abdullah Brooks of Johns Hopkins University in Baltimore, Maryland, was based in a poor district of Dhaka in Bangladesh. When field workers observed symptoms typical of flu or pneumonia, such as fever or coughing, they referred children to clinics, where project doctors took nasal washes to test for influenza.
More than 12,000 cases were referred during the study, with more than 7,500 of them developing into full-blown pneumonia. Brooks and his colleagues were able to follow the fate of 5,000 children under the age of five over a three-year period. The influenza virus was present in about 13% of children tested.
"Tellingly, we found that two-thirds of these influenza-associated pneumonias occurred in very young children — those under two years old," says Brooks. "That didn't surprise us because complications of influenza are known to occur more frequently in this age group."
The work is to be published in The Pediatric Infectious Disease Journal1.
Secret agent
Hospital-based studies carried out during the past few years in India, Thailand and Hong Kong have indicated that influenza has a significant association with pneumonia. But this is the first prospective, population-based study in a tropical or subtropical area to analyse the problem more rigorously. Similar studies are now ongoing in other countries, including Kenya.
Until recently, influenza has not been considered very seriously in developing countries, which have many pressing health problems. Surveillance of the virus, so well-established in the West, is poor in these regions.
Around half of all severe or fatal pneumonia cases are associated with one of two bacterial infections, Haemophilus influenzae type b (Hib) or Streptococcus pneumoniae, or 'pneumococcus'. The Global Alliance on Vaccines and Immunisation has introduced new vaccines against Hib in many countries during the past four years, and in 2007 launched a programme to introduce pneumococcal vaccines. During the past few years, field researchers have begun to seek agents responsible for the other 50% of these cases.
"There is a ragbag of possible agents, from other bacteria to viruses or mycobacteria," says Anthony Scott of the Wellcome Trust's KEMRI Research Programme in Kilifi, Kenya. "But influenza certainly seems to be important among these — we are also seeing significant involvement of influenza at this sort of rate in our preliminary studies here."
The impact of the influenza virus in pneumonia and pneumonia deaths may be even greater than the Bangladesh study suggests, says Brooks, because some viral infections may escape detection. Before they disappear, viral infections can strip the trachea of its cilia — the mobile extensions of the cells lining the trachea that normally stop bacteria entering the lungs. So it is likely that many bacterial infections occur because influenza paves their way, he says.
Prevention effort
In the west, vulnerable people are vaccinated annually and vaccination strains are continually updated because the influenza virus mutates rapidly.
Brooks is now organizing funding for a US$5-million, three-year flu-vaccine trial involving 3,000 children that he hopes to launch early next year to find out how many pneumonia deaths could be avoided in future.
"The goal of our vaccination programme is to reduce pneumonia deaths as much as possible, and most of these occur in the under-twos," says Brooks. So he plans to vaccinate children once, at the age of 9–12 months.
A separate study is being planned by Mark Steinhoff of the Cincinnati Children's Hospital in Ohio to vaccinate pregnant women in their third trimester so as to protect newborns. Steinhoff's pilot study showed that vaccinating women against influenza in late-stage pregnancy reduces flu infection in infants under six months of age by more than 60% 2.
"Doing a vaccine study like this is very interesting because you can look at the whole causal chain," says Scott. "Influenza-virus vaccine may well prevent a proportion of bacterial pneumonia cases in addition to reducing influenza."
"Not only is influenza underestimated, but so are its consequences," says David Salisbury, chairman of the World Health Organization's Strategic Advisory Group of Experts (SAGE) on Immunization, Vaccines and Biologicals. "We know that pneumonia in developing countries has a high burden of morbidity and mortality, and Abdullah's suggested strategy of vaccinating against flu could diminish both its direct and indirect effects."
References
Brooks, W. A. et al. Ped. Infect. Dis. J. doi: 10.1097/INF.0b013e3181bc23fd (2009).
Zaman, K. et al. N. Engl. J. Med. 359, 1555-1564 (2008).
http://www.nature.com/news/2009/091005/full/news.2009.972.html?s=news_rss
- Vaccinating women against influenza in late-stage pregnancy reduces flu infection in infants under six months of age by more than 60%
Flu virus behind infant pneumonia in poor countries
Viral infection precedes an unexpectedly large proportion of childhood pneumonia cases.
Alison Abbott
Influenza may be a surprisingly important player in childhood pneumonia deaths in developing countries, a study has found 1. Pneumonia is the leading cause of death in under-fives worldwide — in poor countries more than one-fifth of childhood mortality is attributed to the disease.
The study, led by Abdullah Brooks of Johns Hopkins University in Baltimore, Maryland, was based in a poor district of Dhaka in Bangladesh. When field workers observed symptoms typical of flu or pneumonia, such as fever or coughing, they referred children to clinics, where project doctors took nasal washes to test for influenza.
More than 12,000 cases were referred during the study, with more than 7,500 of them developing into full-blown pneumonia. Brooks and his colleagues were able to follow the fate of 5,000 children under the age of five over a three-year period. The influenza virus was present in about 13% of children tested.
"Tellingly, we found that two-thirds of these influenza-associated pneumonias occurred in very young children — those under two years old," says Brooks. "That didn't surprise us because complications of influenza are known to occur more frequently in this age group."
The work is to be published in The Pediatric Infectious Disease Journal1.
Secret agent
Hospital-based studies carried out during the past few years in India, Thailand and Hong Kong have indicated that influenza has a significant association with pneumonia. But this is the first prospective, population-based study in a tropical or subtropical area to analyse the problem more rigorously. Similar studies are now ongoing in other countries, including Kenya.
Until recently, influenza has not been considered very seriously in developing countries, which have many pressing health problems. Surveillance of the virus, so well-established in the West, is poor in these regions.
Around half of all severe or fatal pneumonia cases are associated with one of two bacterial infections, Haemophilus influenzae type b (Hib) or Streptococcus pneumoniae, or 'pneumococcus'. The Global Alliance on Vaccines and Immunisation has introduced new vaccines against Hib in many countries during the past four years, and in 2007 launched a programme to introduce pneumococcal vaccines. During the past few years, field researchers have begun to seek agents responsible for the other 50% of these cases.
"There is a ragbag of possible agents, from other bacteria to viruses or mycobacteria," says Anthony Scott of the Wellcome Trust's KEMRI Research Programme in Kilifi, Kenya. "But influenza certainly seems to be important among these — we are also seeing significant involvement of influenza at this sort of rate in our preliminary studies here."
The impact of the influenza virus in pneumonia and pneumonia deaths may be even greater than the Bangladesh study suggests, says Brooks, because some viral infections may escape detection. Before they disappear, viral infections can strip the trachea of its cilia — the mobile extensions of the cells lining the trachea that normally stop bacteria entering the lungs. So it is likely that many bacterial infections occur because influenza paves their way, he says.
Prevention effort
In the west, vulnerable people are vaccinated annually and vaccination strains are continually updated because the influenza virus mutates rapidly.
Brooks is now organizing funding for a US$5-million, three-year flu-vaccine trial involving 3,000 children that he hopes to launch early next year to find out how many pneumonia deaths could be avoided in future.
"The goal of our vaccination programme is to reduce pneumonia deaths as much as possible, and most of these occur in the under-twos," says Brooks. So he plans to vaccinate children once, at the age of 9–12 months.
A separate study is being planned by Mark Steinhoff of the Cincinnati Children's Hospital in Ohio to vaccinate pregnant women in their third trimester so as to protect newborns. Steinhoff's pilot study showed that vaccinating women against influenza in late-stage pregnancy reduces flu infection in infants under six months of age by more than 60% 2.
"Doing a vaccine study like this is very interesting because you can look at the whole causal chain," says Scott. "Influenza-virus vaccine may well prevent a proportion of bacterial pneumonia cases in addition to reducing influenza."
"Not only is influenza underestimated, but so are its consequences," says David Salisbury, chairman of the World Health Organization's Strategic Advisory Group of Experts (SAGE) on Immunization, Vaccines and Biologicals. "We know that pneumonia in developing countries has a high burden of morbidity and mortality, and Abdullah's suggested strategy of vaccinating against flu could diminish both its direct and indirect effects."
References
Brooks, W. A. et al. Ped. Infect. Dis. J. doi: 10.1097/INF.0b013e3181bc23fd (2009).
Zaman, K. et al. N. Engl. J. Med. 359, 1555-1564 (2008).
http://www.nature.com/news/2009/091005/full/news.2009.972.html?s=news_rss