Health
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Invasive pneumococcal disease

Page content: Victorian statutory requirement | Infectious agent | Identification | Incubation period | Public health significance & occurrence | Reservoir | Mode of transmission | Period of communicability | Susceptibility & resistance | Control measures | Outbreak measures | Additional sources of information

Victorian statutory requirement

Invasive pneumococcal disease (Group B disease) requires notification in writing within five days of diagnosis.

Infectious agent

Streptococcus pneumoniae is a gram-positive Streptococcus of which 90 serotypes are known to cause disease. Worldwide, approximately 23 serotypes account for the majority of infections.

Identification

Clinical features
Invasive pneumococcal disease commonly presents as septicaemia, meningitis and pneumonia. Septicaemia and meningitis are more common in children (with the exception of Aboriginal children who present most commonly with pneumonia), while pneumonia is more frequent in adults. Other clinical presentations include septic arthritis, peritonitis, pleurisy and pericardial abscess.

Method of diagnosis
Identification of the organism by culturing it from a normally sterile site like blood or cerebrospinal fluid or by nucleic acid tests such as PCR. Rapid antigen detection tests are available but they are of limited use in the diagnosis of invasive disease in children due to the frequency of pharyngeal pneumococcal carriage.

Incubation period

The incubation period is one to three days.

Public health significance & occurrence

S. pneumoniae is one of the most common causes of bacterial meningitis, septicaemia and pneumonia worldwide. Indigenous children in central Australia have the highest reported rates of invasive pneumococcal disease worldwide. The overall incidence rate in Victoria is approximately 9 per 100 000 population per year, with an overall case fatality rate approaching eight per cent. Rates of disease are highest in children aged less than two years and persons aged 65 years and over.

The prevalence of antibiotic resistance is increasing. Approximately 12% of isolates in 2001 in Australia were resistant to penicillin and five per cent were resistant to third generation cephalosporins. The prevalence of antibiotic resistant differs by State and Territory.

Reservoir

S. pneumoniae are commonly found in the upper respiratory tract of humans.

Mode of transmission

Respiratory droplets, direct oral contact or indirect contact through articles freshly soiled with respiratory discharges.

Period of communicability

Bacteria are communicable in respiratory infections, until discharge from the mouth and nose no longer contain virulent pneumococci in significant numbers. Penicillin renders patients with susceptible strains non-infectious within 24–48 hours.

Susceptibility & resistance

Everyone is susceptible to infection, however the risk of invasive disease is highest for those aged less than two years and the elderly. Other risk factors include prematurity and low birth weight, immunosuppressive therapy and exposure to tobacco smoke. Chronic illness such as asplenia, sickle cell disease, cardiovascular disease, diabetes mellitus, cirrhosis, Hodgkin’s disease, lymphoma, multiple myeloma, renal failure, nephrotic syndrome, HIV infection and recent organ transplant are also risk factors for infection. Immunity is thought to be serotype specific.

Control measures

Preventive measures
A 7-valent pneumococcal conjugate vaccine (7vPCV) and a 23-valent polysaccharide pneumococcal (23vPPV) vaccine are both available in Australia. Approximately 86% of serotypes causing disease in non-Indigenous children in Australia (55% in indigenous children) are contained in the 7vPCV, and 93% of those causing adult disease are contained in the 23vPPV.

In Australia the 23vPCV is recommended on the Australian Standard Vaccnation Schedule for all persons aged 65 years and over, those in high risk groups and all Indigenous persons aged 50 years or more. The vaccine is funded for all persons aged 65 years and over and indigenous persons aged 50 years or more, and those aged 15–49 years in certain high risk groups.

The 7vPCV is recommended on the ASVS for all children at two, four and six months of age. From 1 January 2005 this vaccine will be funded under the National Immunisation Program. Refer to The Australian immunisation handbook (National Health and Medical Research Council).

Control of case
Penicillin remains the treatment of choice until antibiotic sensitivities are obtained. Patients who are allergic to penicillin may be given cephalosporins or erythromycin for pneumonia and chloramphenicol for meningitis. Attempt to obtain blood or CSF specimens prior to commencing therapy however treatment should not be delayed in children and infants, particularly if the clinical presentation suggests septicaemia or meningitis. Consult the current version of Therapeutic guidelines: antibiotic (Therapeutic Guidelines Limited).

Respiratory isolation may be warranted in hospitals for patients with infection due to an antibiotic resistant strain to reduce the risk of transmitting it to other patients at high risk of pneumococcal disease.

Control of contacts
Investigation of contacts is of no practical value.

Control of environment
Disinfect or destroy articles contaminated with discharges from the nose and throat or from other infected sites.

Outbreak measures

In outbreaks in institutions or in other closed population groups immunisation could be considered.

Additional sources of information