Surveillance of acute flaccid paralysis in theNetherlands, 1992-94P.M. Oostvogel,1 M.A.E. Conyn-van Spaendonck,2 R.A. Hirasing,3 &A.M. van Loon4

Detection and investigation of all cases of acute flaccid paralysis (AFP) in children below 15 years ofage areamong the criteria for poliomyelitis-free certification. In the absence of poliomyelitis the incidence ofAFP isaround 1 per 100000 children aged < 15 years. In the Netherlands, surveillance of AFP began in October1992 under the supervision of the Dutch Paediatric Surveillance System (NSCK). Over 90% of clinicallyactive paediatricians participated in the monthly reporting of new cases of AFP.

From October 1992 to December 1994 (27 months), 52 cases ofAFP were reported. The incidence was0.7 per 100000 over the period, and reported cases were evenly distributed throughout the country. Themain cause ofAFP was Guillain-Barr6 syndrome. The average time between onset ofsymptoms and visitinga doctor was less than 3 days. The median reporting delay was 29 days, although the system was notintended as surveillance for action. Virological examination of faeces was carried out for only 40.4% ofAFPpatients.

The start of the NSCK surveillance system coincided with the 1992-93 outbreak of poliomyelitis in theNetherlands, but only 7 of the 18 children with paralytic poliomyelitis were reported through the AFPsurveillance system. For certification purposes, the present AFP surveillance system in the Netherlandsneeds to be improved with respect to coverage by including neurologists, rapidity of reporting, and complete-ness of laboratory investigations.

IntroductionIn 1988 the 41st World Health Assembly launchedthe initiative to eradicate poliomyelitis by the year2000 (1). The objectives for poliomyelitis eradicationare as follows: no more cases of the disease due towild poliovirus and no more wild poliovirus circula-tion identified anywhere in the world through sam-pling of communities and the environment (2).Subsequently, WHO has developed a plan of actionfor the eradication of poliomyelitis (2). In manyways, the eradication of smallpox provided a success-ful blueprint for poliomyelitis eradication (3). The

I Medical Microbiologist, Research Laboratory for Infectious Dis-eases, WHO Collaborating Centre for Reference and Research onPoliomyelitis, Rijks lnstituut voor Volksgezondheid en Milieu(RIVM), Bilthoven, Netherlands. Requests for reprints should besent to this author at the following address: Westeinde Hospital,P.O. Box 432, 2501 CK The Hague, Netherlands.2 Epidemiologist, Centre for Infectious Diseases Epidemiology,RIVM, Bilthoven, Netherlands.3 Paediatrician, Nederlands Signalerings-Centrum Kindergenees-kunde, TNO, Leiden, Netherlands.4 Virologist, Research Laboratory for Infectious Diseases, WHOCollaborating Centre for Reference and Research on Poliomyelitis,RIVM, Bilthoven, Netherlands. Currently: Department of Virology,Eijkman Winkler Institute, University Hospital, Utrecht,Netherlands.Reprint No. 5822

WHO plan identified the programmatic priorities tobe (i) immunization, (ii) surveillance and, at the finalstage, (iii) certification.

Surveillance focuses on rapid detection of allcirculating wild polioviruses. The implementation ofadequate surveillance of acute flaccid paralysis(AFP) is one of the cornerstones for certification ofthe global eradication of poliomyelitis (4). The fol-lowing standard case definition is used for cases ofAFP: a child under 15 years of age with acute flaccidparalysis (including Guillain-Barre syndrome (GBS))for which no other cause is identified, or a patientof any age for whom poliomyelitis is considered apossible diagnosis. All cases should be investigatedclinically, virologically, and epidemiologically. Forlaboratory testing the collection of two faecalsamples, taken 24 hours apart, is requested. Ade-quate surveillance requires complete reporting ofcases, including "zero cases".

The Global Commission for the Certification ofthe Eradication of Poliomyelitis has defined the cri-teria and process through which global poliomyelitis-free certification will eventually be made (5).High-quality AFP surveillance is of paramount im-portance. At present the following performance in-dicators for AFP surveillance have been defined:

- timely receipt of ¢n80% of expected, routine sur-veillance reports, including zero reporting;

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P.M. Oostvogel et al.

a calculated AFP rate of 1 per 100000 childrenbelow 15 years of age;

- at least 80% of reported AFP cases should beinvestigated within 48 hours; and

all suspected poliomyelitis cases should be inves-tigated in detail, including clinical, epidemiologi-cal, and virological examinations and a 60-dayfollow-up examination for residual paralysis.

Before the start of the AFP surveillance in theNetherlands in 1992, cases of poliomyelitis had beenabsent since 1978. The immunization coverage of 1-year-olds in this country had been around 97% formany years. The Netherlands is one of the few coun-tries relying exclusively on inactivated poliovirusvaccine (IPV) rather than oral poliovirus vaccine(OPV), which remains the vaccine of choice for glo-bal eradication. Immunized children were consid-ered well protected against poliomyelitis (6). Thereis, however, a clearly recognizable high-risk group inthe Netherlands: persons refusing vaccination forreligious reasons. In the Netherlands, poliomyelitis isa notifiable disease, such that immediate reporting atsuspicion is compulsory. This passive poliomyelitissurveillance system was extended when a paediatricsurveillance system known as the Netherlands Pae-diatric Surveillance Centre (NSCK) started. Thereasons for including AFP-surveillance within theNSCK network were as follows: to evaluate the fea-sibility of the system as a national AFP surveillancesystem; to measure the annual incidence of AFP; andto obtain further information on the causes of AFPin the absence of poliomyelitis. This article presentsthe results of the first 27 months of the NSCK sur-veillance of AFP.

Materials and methodsThe objective of the NSCK surveillance system is toobtain information on rare childhood disorders witha low prevalence at the national level. The systembegan in October 1992 with support from the Minis-try of Public Health, Welfare and Sports. The systemis similar to the British Paediatric Association Sur-veillance Unit (7) and is based on reporting by allclinically active paediatricians through the monthlyreturn of a card listing a limited number of raredisorders. All paediatricians have received this easilyrecognizable reporting card each month since Octo-ber 1992 and are asked to indicate new cases ofthe listed disorders identified during the previousmonth, with initials and data of birth. All cards arereturned to the NSCK, thereby including negativefindings. The NSCK reports back monthly to the

various investigators, who then contact the reportingphysicians to collect further clinical and laboratorydetails of the patients. AFP has been included in thesystem since the outset and the following case defini-tion is used: all children with acute flaccid paralysis,including bulbar paralysis.

ResultsResponse. The rate of returned cards reached highlevels shortly after introduction of the surveillancesystem. The response rate was 87% in 1992, 91% in1993, and 93% in 1994.

Reported AFP cases. Between 1 October 1992 and31 December 1994, a total of 61 patients with AFPwere reported to the NSCK. By means of question-naires, additional clinical and laboratory data werecollected from the reporting paediatricians. Of the61 questionnaires issued, 57 (93.4%) were returned.Four patients did not match the case definition; twohad contracted poliomyelitis abroad some time inthe past; and one patient was reported twice. There-fore, a total of 52 reports (85.2%) were eligible forfinal analysis.

Timeliness of reporting. For the 52 patients, the me-dian interval between the onset of illness and report-ing to the NSCK was 29 days.

Age and sex distribution. The average age of theAFP patients was 7.2 years. There were 34 boys and18 girls, giving a male-to-female ratio of 1:0.53. Onlyin one case was the patient above 15 years ofage. The age and sex distribution of the 52 reportedAFP patients, including the confirmed poliomyelitispatients (see below) is given in Table 1.

Geographical distribution of AFP in the Neth-erlands. As indicated by their postal area codes, the

Table 1: Age and sex distribution of 52 reported casesof AFP in the Netherlands from October 1992 to De-cember 1994, including seven confirmed poliomyelitiscases

Age group (years)

0 1-4 5-9 10-14 15-19 Total

Female 3 5 1 9(2)a 0 18(2)Male 2(2) 12(1) 1 1 8(2) 1 34(5)

Total 5(2) 17(1) 12 17(4) 1 52(7)

a Figures in parentheses are the number of reported patients withconfirmed paralytic poliomyelitis.

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reported AFP patients were evenly distributed overthe country.

Reported diagnoses, signs and symptoms. Thereported final diagnoses of AFP cases are given inTable 2, along with the sex and age characteristics ofpatients according to diagnosis. For 18 AFP-patientsthere was an association with an infection, includingpoliomyelitis (7 cases), varicella-zoster virus (2cases). Borrelia burgdorferi (4 cases), and Salmo-nella group D, adenovirus, influenza B virus,echovirus, and viral meningitis of unknown origin(1 case each). GBS was the final diagnosis in 16 cases,of which 5 (31.2%) were associated with infec-tion, including 2 cases of Mycoplasma pneumoniaeinfection, and 1 case each of Epstein-Barr virus,cytomegalovirus and influenza virus infections.Clinical signs other than parasthesia and motor dis-turbances were absent among GBS patients. AFPresulted from illness in two cases, including onepatient with contusio medullae spinalis and onewith post-traumatic syringomyelia. The remainingtwo diagnoses of AFP resulted from phosphofruc-tokinase deficiency and arteria spinalis anterior syn-drome. In 14 cases of reported AFP (26.9%), thefinal diagnosis remained unknown.

Clinical characteristics such as motor distur-bances, fever, meningism, paraesthesia and sensibil-ity disturbances, summarized according to diagnosis,are given in Table 3. Motor disturbances were, ofcourse, reported for all patients.

Fever occurred in 85.7% of the poliomyelitispatients (see below), in 84.6% of those with otherinfections, and in 12.5% of GBS patients. Meningismoccurred in 42.9% of NSCK-reported poliomyelitiscases.

All poliomyelitis cases were confirmesl by isola-tion of wild poliovirus from stool samples. Stool sam-

ples were investigated in only 38.2%, 31.3%, and33.3%, respectively, of the patients with other infec-tions, GBS, or unknown diagnosis. Throat swabs forvirus isolation were taken in 23.1%, 12.5%, and41.7%, respectively, of the patients in the above-mentioned groups.

AFP rate

Table 4 shows the reported rate of AFP cases per100000 population under the age of 15 years as wellas the number of cases expected on the basis of anincidence of 1 per 100000. The expected number ofAFP cases annually was 28 per 100000 population inthe Netherlands during the study period. BetweenOctober and December 1992, 10 cases were re-ported, of which 4 were due to poliomyelitis. In 1993,23 cases were reported, including 3 due to poliomy-elitis. In 1994 there were 19 cases of AFP. The AFPrates in the years 1992, 1993 and 1994 per 100000population under 15 years of age were therefore1.45, 0.82, and 0.67, respectively, including poliomy-elitis patients, and 0.87, 0.72, and 0.67, respectively,excluding such patients. Therefore, a fairly constantrate close to 0.7 per 100000 was seen over the report-ing period.

The poliomyelitis outbreak of 1992-93

A nationwide outbreak of poliomyelitis occurred inthe Netherlands between September 1992 and Feb-ruary 1993 (8). This outbreak partially interferedwith the study objective of detecting the rate andcauses of AFP in the absence of wild poliovirus cir-culation. However, it did allow us to evaluate thesensitivity of the AFP surveillance system. A total of18 patients aged <15 years with paralytic poliomyeli-tis were notified to the public health authorities dur-

Table 2: Final diagnoses of AFP and patients' characteristics

Male-to-female Mean ageDiagnosis n ratio (years)

Infection 18 (34.6)a 1:0.39 7.7; 0.25-14.9bPoliomyelitis 7 (13.5) 1:0.40 8.7; 0.25-14.5Other 11 (21.2) 1:0.38 7.0; 1-13.1

Guillain-Barr6 syndrome 16 (30.8) 1:0.46 7.7; 2.5-15.6Post-trauma 2 (3.8) 1:1 4.8; 4.4- 5.2Otherc 2 (3.8) 1:1 6.7; 0.1-13.4Unknown 12 (23.1) 1:0.5 6.3; 0.1-13.8

Total 52 (100) 1:0.53 7.2; 0.1-15.6

a Figures in parentheses are percentages.b Figures in italics are the age range.c One patient had phosphofructokinase deficiency and one had arteria spinalis anteriorsyndrome.

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Table 3: Clinical signs and symptoms for different diagnostic groups of AFPcases

% of patients exhibiting symptoms:

Motor SensibilityDiagnosis distubances Fever Meningism Parasthesia disturbances

InfectionPoliomyelitis 100 85.7 42.9 28.6 14.3Other 100 84.6 15.4 15.4 15.4

Guillain-Barre syndrome 100 12.5 6.3 37.5 6.3Post-trauma 100 0 0 0 50Other 100 0 0 50 50Unknown 100 33.3 8.3 25.0 33.3

All diagnoses 100% 44.2 13.5 26.9 19.2

Table 4: Expected and reported AFP cases per 100000 population aged <15years, and the NSCK response rate, October 1992 to December 1994

No. of AFP casesPopulation NSCK

Year <15 yearsa Expectedb Reported AFP ratec response (%)d

1992 (3 months) 2764914 7 10(6)- 1.45 (0.87) 871993 2791061 28 23(20) 0.82 (0.72) 911994 2815732 28 19 0.67 93

Total - 63 52 0.71 90

a Data provided by the National Office for Statistics.b Based on an AFP incidence of 1 per 100000 population <15 years of age.c Cases per 100000 population aged <15 years per year.d Proportion of all paediatricians returning completed reports monthly.e Figures in parentheses are number of cases excluding confirmed poliomyelitis cases.

ing the outbreak. Of these, only 7 cases were con-firmed poliomyelitis, including 2 males aged <1 year,1 male in the 1-4-year-old age group and 4 cases (2girls and 2 boys) in the 10-14-year-old group (Table1). The male-to-female ratio for these seven con-firmed poliomyelitis cases was 1:0.40. Fig. 1 presentsthe monthly reported number of casesin the NSCK surveillance system, including theconfirmed poliomyelitis cases, by data of onsetof disease. No previously unconfirmed cases ofpoliomyelitis were detected by the surveillancesystem.

Discussion and conclusionsWith the ongoing success of the eradication initia-tive, surveillance of patients with poliomyelitis andof wild poliovirus circulation is becoming increas-ingly important. In the end stage of eradication, it

will be crucial to document convincingly the absenceof disease cases and of wild poliovirus circulation.Only then can the world be declared free of poliomy-elitis and vaccination be stopped.

Surveillance of AFP is the cornerstone of ad-equate poliomyelitis surveillance as requested by theGlobal Commission for the Eradication of Poliomy-elitis (5). Only because of the presence of a highquality AFP surveillance system could the Americasbe declared poliomyelitis free in 1994 (9). AFP sur-veillance has been implemented successfully in coun-tries emerging as poliomyelitis free, most notably inLatin America and the Caribbean. In Oman, a well-organized AFP surveillance system was imple-mented after the outbreak in 1988 and led to thedetection of a poliovirus type 3 epidemic (10). Whilethe need for AFP surveillance has been well estab-lished in countries recently free of poliomyelitis, thenecessity and feasibility of AFP surveillance in de-veloped countries that have been free of the disease

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Surveillance of AFP in the Netherlands, 1992-94

Fig. 1. Number of cases of acute flaccid paralysis (AFP) reported per monthin the Netherlands from September 1992 to December 1994, by date ofonset of disease.

6

5-

I-

0

0

;g 2-

1

ES AFP patients, confirmed as poliomyelitise Other AFP patients

ISept Jan92 93

Jun.1.

Dec Jan94

Jun.1 .1.1.

DecWHO 97448

for many years is less clear. Countries such as theUnited Kingdom, where poliomyelitis has been ab-sent for 10 years or even longer, have reported ontheir experience with AFP surveillance (11). A feasi-bility study on AFP surveillance was started in theNetherlands in October 1992 as part of the NSCKsurveillance system of rare childhood diseases, andprovides excellent access to practising paediatriciansin the Netherlands. In May 1992 investigators atthe Rijks Instituut voor Volksgezondheid en Milieuproposed that AFP surveillance be included in theNSCK system. Once the scientific board of NSCKhad been convinced of its usefulness, AFP was addedto the list of rare conditions covered by the surveil-lance system. The system requires little effort fromparticipating paediatricians, who only have to tick abox if cases have occurred and return the postcardonce monthly. Shortly after the introduction of theprogramme the average response rate increasedrapidly to reach a stable 90% of the nearly 400 prac-tising paediatricians over the period studied. Thisrate is slightly higher than those in the action-oriented surveillance system in the Americas, whereapproximately 80% of all health facilities reportweekly.

Excluding patients with poliomyelitis, the inci-dence of reported AFP cases was 0.7 per 100000population <15 years of age over the entire studyperiod. It peaked at 1.45 per 100000 around the po-liomyelitis outbreak in 1992. The overall AFP inci-dence is slightly less than the benchmark rate and

that reported from most other countries with ad-equate AFP surveillance. For the Region of theAmericas the AFP reporting rate between 1988and 1995 ranged from 1.20 to 1.35 per 100000 popu-lation aged < 15 years (12). In 1996 the overall ratefor this region was 1.20; the rates per reportingcountry varying from 0.04 (HAI) to 2.53 (ELS)per 100000 population aged < 15 years (13). Theaverage AFP rate in Oman was 2.1 per 100000 popu-lation aged <15 years, with a variation per district of0.5-3.3. In the Czech Republic, Poland, Russian Fed-eration (St. Petersburg), Turkey, and the Ukraine,AFP rates of 0.3, 0.6, 2.6, 0.5, 1.7, and 0.7 per 100000population, respectively, have been reported (WHO,unpublished data).

Data on AFP incidence from Western Euro-pean countries are scarce and have to our knowledgeonly been published for the United Kingdom. Theaverage AFP incidence in the BPSU surveillancewas 0.38 per 100000 population under 16 years ofage for the period July 1991 to June 1994, and de-clined from 0.48 per 100000 in 1991 to 0.23 per100000 in 1994. The age and sex distributions of ourpatients were comparable to those found in theUnited Kingdom.

The reasons for the differences in AFP ratesamong countries are unclear. Comparison of thevarious final clinical diagnoses in the surveillancesystems of the Region of the Americas and theUnited Kingdom with our data is difficult because ofthe relatively large percentage of patients for whom

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P.M. Oostvogel et al.

the final diagnosis was not reported. It is remarkable,however, that the percentage of patients with GBS inour study is well below that in the PAHO and UnitedKingdom studies (30% versus approximately 60%).This difference may have arisen because some of thepaediatricians covered by the NSCK system werenot aware that GBS fell within the case definition ofAFP.

The specificity of our surveillance system ap-peared to be satisfactory; only 4 of the 52 reportedcases did not match the case definition. The sensitiv-ity, however, was poor. The objective of AFP sur-veillance is to detect all cases of poliomyelitis. Theconcurrent poliomyelitis outbreak in the Nether-lands in 1992-93 allowed us to determine the sensi-tivity of AFP surveillance at detecting cases ofpoliomyelitis. Of the 71 officially registered patientswith poliomyelitis during the 1992-93 outbreak, 59were paralytic and of those, 18 were aged <15 years.Only 7 of these 18 cases (39%) were reported toNSCK (Fig. 2). This low sensitivity is probably be-cause most poliomyelitis patients were seen by theirgeneral practitioner and were referred directly to aneurologist and not a paediatrician. In consequence,they were not reported to NSCK. Thus, to improvecoverage in the Netherlands, AFP surveillanceshould be extended to include neurologists. In othercountries with highly specialized health care systems,AFP patients may be seen by paediatricians or neu-rologists. Countries considering implementation ofAFP surveillance should take this into account. Inview of the long period between onset of illness andreporting (median, 29 days), the Dutch AFP surveil-lance in its present form is not suitable for immediateaction. Rapid reporting was, so far, not one of the

Fig. 2. Sensitivity of reporting poliomyelitis cases tothe NSCK during the outbreak of poliomyelitis in theNetherlands, September 1992-February 1993. Shownare AFP cases confirmed as poliomyelitis andreported to the NSCK, and the total number of casesof paralytic poliomyelitis. Data are for the Dutchpopulation under 15 years of age.

& Cases of pamlysis notified dunng outbreakamong under-15-year-olds

* Cases of poliomyelitis reported asAFP10

CD

co-,s l L

0

surveillance system objectives, in contrast to that inthe United Kingdom. It would, however, be quitefeasible to improve the speed at which AFP cases arereported, thereby permitting immediate action to betaken. For this purpose, telephone reporting will beintroduced shortly, along with other measures toimprove the system.

Adequate virological examination was per-formed for less than 50% of patients (data notshown). Virus isolation from faeces or throat swabswas attempted for only 40.4% and 25% of the pa-tients, respectively, including all poliomyelitis pa-tients. In one third of all AFP patients, virologicalexamination was not carried out at all. Therefore,poliomyelitis cannot be excluded for some patients.For example, one AFP patient living in the areawhere the poliomyelitis outbreak started in theNetherlands in 1992 became ill on 15 September1992, a total of 2 days before the index patient wasnotified. No virological examination was carried outand no information on the immune status of thisAFP case was available. The case was reported to theNSCK system only in early 1993. Clearly there is astrong need to improve virological examination ofpatients with AFP. Acute-onset flaccid paralysisitself is a syndrome with numerous possible causesand will continue to occur worldwide even after com-plete eradication of poliovirus (14). Clinically,poliomyelitis is quite difficult to distinguish fromother causes of AFP. As observed by PAHO (15),our data confirm fever to be a good parameterto distinguish poliomyelitis from other infectiousdiseases or GBS.

It is clear that in its present form the Dutch AFPsurveillance system does not meet the requirementsset by the Global Commission on the Certification ofthe Eradication of Poliomyelitis. Performance indi-cators are not being met with regard to AFP rate,timeliness of reporting, and adequate epidemiologi-cal and virological investigations. In addition, anexpert committee for classification of cases has notbeen established. The main reason that the systemdoes not yet meet the required performance level isthat it started as part of a surveillance system for anumber of rare conditions. The emphasis was ondetermining the incidence and causes of these condi-tions, and not on investigating and following-upthese cases. Using this approach it was fairly easy tointroduce AFP surveillance, but it will be more diffi-cult to improve the system to the required perform-ance level.

Our report shows that improvements areneeded, particularly with regard to the sensitivity ofthe system, the timeliness of reporting and especiallylaboratory investigation of AFP cases. It is crucialthat laboratories correctly identify polioviruses; to

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Surveillance of AFP in the Netherlands, 1992-94

this end, a global network has been developed fortechnical support (16). Paralytic illness may also bedue to other enteroviruses, notably enterovirus 71(17), and a recent study in Brazil stressed the impor-tance of detecting and correctly typing enterovirusesas possible causes of AFP (18).

In countries where poliomyelitis has apparentlybeen eradicated for many years, flexibility will beneeded in the Global Commission's assessment ofthe absence of circulating wild poliovirus. Furtherdocumentation and definition of acceptable tech-niques in such countries is needed (5). In order todetect all circulating polioviruses, all clinically sus-pect cases of AFP should be identified and investi-gated by virological examination.

The Netherlands continues the present AFPsurveillance system, with increased attention on thelaboratory aspects. Additionally, increased aware-ness of the poliomyelitis eradication initiative shouldimprove the overall performance.

ResumeSurveillance de la paralysie flasqueaigue aux Pays-Bas, 1992-1994La qualite de la surveillance de la paralysie flasqueaigue (PFA) sera l'un des criteres qui serviront debase a la certification de l'eradication mondiale dela poliomy6lite. On sait, grace a l'initiative pourl'6radication de la polio-myelite dans les Ameriques,que l'incidence de la PFA en I'absence depoliomy6lite est voisine de 1 pour 100000 enfantsde moins de 15 ans. Une surveillance ad6quate despatients atteints de PFA doit comporter des investi-gations virologiques (isolement et typage du virus)pour exclure la poliomy6lite. Le systeme actuel desurveillance de l'eradication de la poliomyelite dansla Region des Ameriques signale de 2000 a 2500cas par an et s'appuie sur plus de 20000 unitessanitaires; aucun poliovirus sauvage n'a ete decel6dans la region pendant les 5 annees passees. Horsdes Am6riques, la surveillance de la PFA a debuteplus r6cemment. Si la mise en ceuvre de cette sur-veillance dans les pays d'end6mie ou indemnes depoliomyelite depuis peu n'est pas contest6e, sonintroduction dans les pays sans cas de poliomy6litedepuis plus longtemps n'est pas bien accept6e.

Cet article rapporte les r6sultats de la surveil-lance de la PFA aux Pays-Bas d'octobre 1992 ad6cembre 1994. Depuis octobre 1992, la surveil-lance pratiqu6e aux Pays-Bas consiste a inclure lescas d6clar6s de PFA dans le systeme nouvellementcre6 par le centre de surveillance pediatriquen6erlandais (NSCK). Ce systeme s'attache plus a

recueillir les donnees de l'incidence que des infor-mations permettant une intervention rapide. 11 estdemande a tous les p6diatres n6erlandais ayantune activite clinique (soit 400 environ) de d6clarerchaque mois les cas de PFA, y compris zero cas.Apres chaque notification au NSCK, les p6diatresre9oivent un questionnaire qui permet de recueillirdes donnees cliniques et diagnostiques comple-mentaires. En 27 mois (octobre 1992-decembre1994) 52 cas de PFA ont ete declares. L'incidence6tait donc de 0,7 pour 100000 pour la periode,chiffre qui est rest6 relativement constant au coursdu temps. Le rapport de masculinit6 etait de 1:0,53et l'age moyen de 7,2 ans. La mediane du tempsqui separe le d6but de la maladie de la declarationau NSCK est de 29 jours. Les cas sontuniform6ment r6partis dans tout le pays. Commeailleurs, la cause principale de la PFA est le syn-drome de Guillain-Barr6

La mise en place de la surveillance de la PFAaux Pays-Bas a coincid6 avec la flamb6e de polio-myelite de 1992-1993 dans ce pays. Sur 18 casdeclares de poliomyelite paralytique avant l'age de15 ans, 7 ont ete declares grace au NSCK. Cefaible taux de d6claration est peut-etre dO a ce queles patients n'ont pas consult6 un pediatre, maisplut6t un gen6raliste ou un neurologue.

Le pourcentage d'examens virologiques apartir d'echantillons de selles des patients estremarquablement bas (40,4%). La recherche dudiagnostic par isolement du virus et typage estnecessaire, non seulement pour exclure la polio-myelite, mais encore pour mieux connaitre lesautres causes de PFA. Si la surveillance de laPFA se poursuit dans des pays ou la poliomyeliteest apparemment elimin6e depuis plusieursannees, comme aux Pays-Bas, il est recommanded'y inclure les d6clarations de PFA par lesneuro-logues. L'attention est egalement attir6e surla rapidit6 de la d6claration et la realisationd'examens microbiologiques complets des cas dePFA.

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