Acute flaccid paralysis surveillance in Australia

Editor – In October 2000 the Western Pacific region of the World Health Organization (WHO) was certified free of circulating wild poliovirus (1). Australia had its last case of poliomyelitis due to wild poliovirus some time in the 1970s (2). However, being certified free of poliomyelitis depended on satisfying a number of criteria, one of which was adequate surveillance for acute flaccid paralysis (AFP) in children aged 0–15 years (3). AFP surveillance commenced in Australia in 1995 as a joint initiative of the Australian Paediatric Surveillance Unit (APSU) and the Commonwealth Department of Health (4), with the Victorian Infectious Diseases Reference Laboratory being responsible for virological surveillance.

The approach adopted in Australia has been presented in detail elsewhere (4) but is briefly outlined here. Any paediatrician seeing a patient aged 0–15 years, presenting with AFP, was asked to notify the surveillance coordinator by telephone, to complete a detailed questionnaire and to arrange for the collection of two faecal samples 24 hours apart and within 14 days of the onset of paralysis. A follow-up questionnaire requested clinical details 60 days after the onset. In addition, all paediatricians in Australia were asked to indicate each month the number of patients seen with a range of rare conditions, including AFP, by returning a reply-paid survey card to the APSU.

Australia's population aged under 15 years was estimated as approximately 3 922 000 in 1999. To fulfil the WHO surveillance target of one AFP case per 100 000 population in this age group (3), Australia would have expected 38–40 AFP cases per year between 1995 and 1999. However, only 24–34 cases with sufficient information for classification by the polio expert committee were notified each year during this period. Adequate stool collection was documented for a maximum of 25% of cases in 1996. It was thus necessary to perform a series of retrospective hospital reviews in order to reach the expected number of AFP cases for Australia's certification requirements (5).

In 2000, staff at the Victorian Infectious Diseases Reference Laboratory undertook responsibility for AFP surveillance in conjunction with the APSU. Table 1 compares results with WHO surveillance targets: 48 cases were notified, of which 43 had sufficient clinical and virological information for classification as non-polio by the polio expert committee. More than 80% of notified cases had two questionnaires completed and/or two stool samples collected, though only 31% of all cases had two samples collected in the manner prescribed by WHO. However, significantly more of the cases with adequate stool samples were first notified by telephone to the AFP surveillance coordinator compared with notification through the routine monthly reporting system (56% compared with 12%, P <0.001).

AFP case identification in excess of target levels has also been achieved in the first five months of 2001. Compared with 17 expected cases, 30 have been notified. To date, clinical information is available on 21 (70%) and at least one stool specimen has been collected on 20 (67%) of these.

Some industrialized countries, including France, the United Kingdom and the United States, do not routinely report AFP surveillance data and others fail to meet the WHO surveillance standards (6). In the year 2000, we have shown that a country with no proven polio case for more than 25 years has been able to find the expected number of AFP cases and investigate more than 80% of them. We believe that having responsibility for clinical and virological surveillance at one site has led to increased efficiency in both aspects of surveillance. Increased awareness by paediatricians of the causes of AFP, and the implications of AFP surveillance for WHO certification, may also have improved surveillance. We have demonstrated the importance of rapid notification for improving adequate faecal sampling. Since surveillance will be required until global certification and beyond, it is important that both non- endemic and recently endemic countries strive to achieve WHO surveillance targets for AFP.

Heath Kelly

Head, Epidemiology Division
Victorian Infectious Diseases Reference
Laboratory
Locked Bag 815, Carlton South 3053, Australia
(email: heath.kelly@mh.org.au)

Kerri Anne Brussen, Scientist
National and Regional Polio Reference
Laboratory
Victorian Infectious Diseases Reference
Laboratory
North Melbourne, Victoria, Australia

Anne Morris, Assistant Director (Medical)
Australian Paediatric Surveillance Unit
Westmead, NSW, Australia

Elizabeth Elliot, Associate Professor
Department of Paediatrics and Child Health
University of Sydney
Director, Australian Paediatric Surveillance Unit

Acknowledgements

All paediatricians notifying cases; the Polio Expert Committee in Australia (Professor John Pearn, Dr Robert Hall, Dr Rennie D'Souza, Margery Kennett); previous investigators with the Department of Health and Aged Care (Dr Rennie D'Souza, Dr Helen Longbottom, Dr Anna Herceg); Nittita Prasopa- Plaizier and staff of the National Polio Reference Laboratory; Dr Jayne Antony and the staff of the Australian Paediatric Surveillance Unit.

Conflicts of interest: none declared.

1. Adams T. Farewell to polio in the Western Pacific. Bulletin of the World Health Organization, 2000, 78:1375.

2. Kennett M et al. Australia's last reported case of wild poliovirus infection. Communicable Diseases Intelligence, 1999, 23: 77–80.

3. Report of the seventh meeting of the Technical Advisory Group on the Expanded Programme on Immunization and Poliomyelitis Eradication, Canberra, 9–13 April 1996. Manila, WHO Regional Office for the Western Pacific, 1997.

4. D'Souza RM et al. Surveillance of acute flaccid paralysis in Australia, 1995–97. Journal of Paediatric Child Health, 1999, 35: 536– 540.

5. D'Souza R et al. Poliomyelitis eradication in Australia. National documentation for certification of poliomyelitis eradication in Australia. Canberra, Commonwealth of Australia, 2000.

6. Performance of acute flaccid paralysis (AFP) surveillance and incidence of poliomyelitis, 2000- 2001. Weekly Epidemiological Record, 2001, 76: 80–83.