News : Vital protection for children

Excerpt from STAR ONLINE

Vital protection for children

With the introduction of the Haemophilus influenzae type b (Hib) vaccine in 2002, S. pneumoniae has replaced Hib as the most common cause of meningitis in children in Malaysia. And now, there’s a vaccine for it, too.

ON 7 OCTOBER 1996, parents around the world went about their daily routine, oblivious to the fact that two scientists they did not know, and would never meet, had discovered something that would impact their lives directly.

It was the day that Peter Doherty and Rolf Zinkernagel were awarded the 1996 Nobel Prize in Physiology or Medicine for their discoveries concerning “the specificity of the cell mediated immune defence”.

Their discovery of how the immune system recognises virus-infected cells “laid a foundation for an understanding of general mechanisms used by the cellular immune system to recognise both foreign microorganisms and self molecules.”

Dr Musa Mohd Nordin and Dr Theodore Tsai agree that the way ahead to prevent invasive pneumococcal diseases in infants and young children is with vaccination.In other words, their work has paved a better platform for the construction of new vaccines, among them the pneumococcal saccharide conjugate vaccine.

This is the first licensed vaccine to protect children under the age of two from invasive pneumococcal disease caused by several of the most common types of the pneumococcal bacteria.

Nasty pathogen
Pneumococcus, formally known as Streptococcus pneumoniae, is a gram-positive bacteria discovered way back in 1881 by French microbiologist Louis Pasteur.
“Pneumococcus contains a sugar capsule (polysaccharide) that encapsulates the bacteria. It is this capsule that makes this germ very infectious,” says Dr Musa Mohd Nordin, consultant paediatrician and neonatologist.

This germ is very easily transmitted via inhalation of aerosols or direct physical contact, for example through a cough or a sneeze.
Once it has landed in your nose, the germ parks itself in there, ready to cause troublesome infections like sinusitis and otitis media (infection of the middle ear).
However, it doesn’t stop there.

S treptococcus pneumoniaeis a nasty pathogen that is the number one cause of sinusitis, otitis media, bacteraemia, pneumonia and meningitis.“(Pneumococcus) breaches the barrier lining of the nose and the pharynx, and enters the blood. When it has invaded the bloodstream, it causes bacteraemia, or blood poisoning,” Dr Musa explains.
The Health Ministry has estimated that the incidence of pneumococcal bacteraemia is about 30 per 100,000 in Malaysian children under five years old, with at least 750 cases and 20 deaths per year.

“And if it goes across the blood-brain barrier into the cerebrospinal fluid, it causes meningitis,” he adds.

Meningitis, where the meninges or the lining of the brain becomes inflamed, is every parent’s worst nightmare. Without prompt diagnosis and treatment, a child with meningitis may die. Even those who survive may have multiple neurological deficits, such as mental retardation, cerebral palsy, blindness, deafness or epilepsy.

“It’s a very tragic survival,” Dr Musa stresses.
Previously, pneumococcus has been overshadowed by the Haemophilus influenzae type b (Hib) bacteria, which was the number one cause for meningitis. However, after the Health Ministry introduced the Hib vaccine in 2002, the rates of Hib meningitis have declined tremendously.
“Now, S. pneumoniae has replaced Hib as the most common cause of meningitis in Malaysia,” Dr Musa points out.

Pneumococcus can also infect segments of the lungs, causing pneumonia. The relentless little germ is actually the number one cause of acute respiratory infections in Malaysia, which is, in turn, the leading cause of childhood illnesses, according to the National Health and Morbidity Survey 1996.

“There are at least 90 different types of pneumococci. But only about eight to 10 of the different pneumococci are responsible for the majority of invasive pneumococcal disease,” says Dr Musa.
His favourite phrase, “pneumococcus is number one” is justified. WHO reports that one million children in the world below the age of five die every year from invasive pneumococcal disease.

Antibiotics not the answer
Gone are the days when antibiotics could be deployed to battle attacks by any bacteria.
Today, bacteria and other microorganisms that cause infections have developed ways to survive drugs meant to kill or weaken them, leading to an emerging public health problem known as “antibiotic resistance”.

“In the 1940s, when penicillin was discovered, it was thought that this was the magic bullet that would eradicate all forms of bacteria. This would be the end of the pneumococcus,” relates Dr Musa.

Instead, the bacteria has managed to clone itself to be resistant to common antibiotics like penicillin and macrolides.

In a study carried out by the Asian Network for the Surveillance of Resistant Pathogens (ANSORP) between 1999 and 2001 in 12 Asian countries, the group concluded that there is a worrying increase in the prevalence of penicillin- and macrolide-resistant pneumococcus.
Antibiotic resistance is believed to arise from the abuse, overuse and misuse of antibiotics. As a result, pneumococcal infections, and many other diseases like tuberculosis, malaria and cholera, are not responding to formerly effective drugs and are spreading rapidly.
In the same study, the ANSORP group recommended that there should be continuous surveillance of pneumococci, while doctors should be more circumspect about the use of antibiotics.

ANSORP also concluded that pneumococcal vaccination is urgently required in Asia, a point that Dr Musa fervently agrees with.

“Antibiotics are not the solution to the pneumococcal problem. The way ahead is to prevent these invasive diseases with vaccination,” he says.

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