Jpn. J. Infect. Dis., 53, 6‑10, 2000

Review

Does Polio Eradication Succeed Meeting the Target Year of 2000?
Isao Arita* and Miyuki Nakane
Agenq,for Cooperation in International Health,
Higashi‑machi 4‑ll‑I, Kumamoto 862‑0901, Japan(Received March 10, 2000. Accepted March 17, 2000)
SUMMARY: The global polio eradication programis under way with the target year of2000･ We reviewed theprogram progress,inperspective, &om the experience of the global smallpox eradication, which is at present asole disease ever eradicated by orchestrated global efforts. We concluded that despite substantial efforts being
made bythe World Health Organizationand member states withthe current progress, it would requlre additionalsome three years, namely 2002. This would safe‑guardthe success.AsofJanuary 2000,there are still at least 22

endemic statesinIndianSubcontinentand sub‑SaharanAfrica. Experiencesinsmallpox eradication, although
the disease is different,indicated that to stop transmissioninsuch a large number of endemic states took morethanthree years, assumlng that further support would come towardthe flnal goal.

developlng world of the other civilizations･The second, namelythe htensified Program, was successful

Introduction

The development ofmedicalteclmology has been remark‑able duringthe last millenium, especiallyinthe last 400 years.

(1 967‑ 19iO). WHO co10rdination effectively motivated all
the civilizations, making the resources available globally･

The circulation of the blood discovered by William Harvey
inthe 17thcentury, openedthe way to scientific managementof curative medicineindeveloped reg10nand smallpox eradica‑tion declared by the Wbrld Health Organization (WHO) in

Many national heads of major Smallpox endemic states placed

the highpriority onthe progrrs･ The strategies were innova‑
tive,including effective vacclne qualitycontroland vacclne
production promotion in selected states, suⅣeillance and

1 980, openedthe way to de血itiveand real equity for distribu‑

containment measuresand establishment of intemationaltion of benefit from medicalscience to all the humanity,

diagnostic laboratories.

namely bothindevelopedandunder‑developed regions (1).

The salient picture of progress of smallpox eradication is

specifically described below (Table I ).

This means, the technology development in curative

medicine has been eqoyed chiefly by Westem civilization

The program started with U.S. bilateral assistance in 19

and its followersincluding Japan, not by other civilizations
such as African, Chinese, Hinduism, Islamic and Latin.

states of Westand Central Africa in 1967. It successfully
stopped the transmission withthe last caseinNigeriain1970･

Perhaps, Smallpox eradication is the first humanattempt in

Massiveinvestment ofintemational persormel (average yearly

the sensethat allthe civilizations worked together regardless

54 U.S. persornel) as well as necessary transport (morethanof their cultureand religions, by mobilizing all the resources100) assured the success.

availableintheir own domains.

In entire Asian Continent, IndianSubcontinent was major

Polio eradication fわllows smallpox eradication aimlng at

reseⅣoir of smallpox. The commencement of the program

the achievement of zero world incidence by 2000. 1t will

was delayed, but,inSeptember 1973, late Indira Gandhi,thencertainly occur in foreseeable future, the end is beginnlng,

prlme minister, India, instructed all the health centers staff

but how farthe end? In this note, its progress, problemand

took one week every month only for search for smallpox,

future was analyzedand forecast based on the experience
gained from smallpox eradication, So that the beginnlng Of
the end should be assured.

Table I. Smallpox eradication

Disease inthe number of endemic states

Success of Smallpox Eradication

BIockArea 楓V

Smallpox eradication, even thoughits remarkable success,dﾆ 7D6 6W2 7F FR No.of Endemic StatesWorldwide

SouthAmerica,

A舟icaandAsia

田rpropeeded withdifrlCulty･ The fmt attempt ( 1 958‑ 1 966) failed
owlng tO the fact that industrialized states, namely Westem

AfricaWest 姪都

civilization did not understand and meet with the need of

ABicaCentral

都ｦAmericaSouth都&*Corresponding author: Tel: +8 1‑96‑367‑8899, Fax: +8 1‑96‑367‑

900 I, E‑mail: acih@msa.biglobe.ne.jp

都"

ABicaSouth都2

AsiaSouthEast
ThisarticleisaReviewpresentedasaspeciallectureatthe
24thKyushuRegionalCongressofJapaneseTropicalDiseases

HomofAkic?
HomofA舟ica

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In polio eradication, as of January 2000, there are 30 polio endemic

EnvironmentalHealth,Kitakyushu.

states (including suspected 8 states).

6

being followed by containment vaccinations. Alter implemen‑tation of this "Autumn Campalgn", India recorded the last

1980.

Inthe ctourse of time, PanAmericanHealthOrganization

caseinMay 1975. Estimatedinvestmentsincluded asslgnment(IhHO) recognizedthe irrmuni2ation programヲina few statesof average 27 intemational and 3 1 mational epidemiologists.

effectively stopplng theindigenous transmlSSion of wild

Similarprogram took place in Bangladesh which recorded

polio. In 1985, PAHO decided to launch reglOnal polio eradi‑theAsianContinent's last caseinOctober 1975, withaverage

cation in Nor也and South America. Notably, PAHO tradi‑

27intemationaland later date 28 national epidemiologistsin

tionally wasinterestedindisease eradication as seenintheirfailed efforts for yellow fever as well as malaria eradication.

1974 and 1975.

Having secured theAsianContinent to be in good odor,

This time, encouraged by success of smallpox eradication,

the WHO's global programwas able to concentrate on thelast battle taking placeinthe Hom of Africa. In factin1976,

they, Including exISmallpox eradication staff, initiated thisnew venture. Being Impressed by PAHO's successful

most ofintemational personnel engagedinAsianContinent

execution, in 1988 WⅥO resolved to comence the global

Auhmn Campalgn j oined nationalandintemational program

eradication of polio by the year of2000.

personnel in Ethiopla and Somalia, the two last reservoirs
states of smallpox. Ethiopla recorded last caseinAugust I 976
and SomaliainOctober 1977. The case detectedinSomalia
is,in fact,the end point of natural smallpox transmission overthe last 6000 yearS･ Since October 1977, continumg surveil‑

In both diseases, there are no animal reservoir, no long‑lance in the Hom of Africa and elsewhere in the world has

termvirus shedding and effective vaccines with affordable

not discovered smallpox until to‑date. Exception was theprice,and lastly, world communityis concemed about thelaboratory associated smallpox casesinBirmingham, U.K.
in1978･ This was quickly contained, but gave a lesson thatbilityof global resource mobilization.

Progress of Polio EradicatiotL aS Comparedwith
That of Smallpox Eradicationdisease burden, which resulted or will resultingreater possi‑

laboratory stocks of smallpox virus did pose realrisk of

The strategy fわr polio eradication is similar to smallpox

reintroduction of smallpox. WHO recommended,therefore,
to destroythe variola virus stocksinall research laboratories,

eradication. The mainstrategies consist of National Immuni‑

having proposed several timesthe dates of destruction.

surveillance. Surveillance contairment measures are also

zation Days (NIDs) and acute flaccid paralysis (AFP)

Asof to‑date, this important post eradication action,

aggressively undertaken in the riskareas. PAHO recorded

regrettably, has not yet been implemented; U.S. and Russia

have been agamstthis policy. Theyfearthe probable presence

the last endemic case ofpolioin1991, WHO Westem PacificRegional Office (WPRO)in1997 and EuropeanRegiona1of smallpox bioweapon and maintain the vims stocks with

0trlCe (EURO)in1998. Teclmical advantage ofpolio eradi‑

dubiousunderstandingthattheir retention of the virus stocks

cation over smallpox eradication is that polio vaccine virus

would prevent the use of such weapon.

can be naturally transmitted to the contacts, thus assurlng

wider vaccination coverage,and that feca1‑oralroute of polio
infection may be lessfrequentthanrespiratory route of small‑Connencement of Polio Eradication

poxinfection. Presence of subclinicalinfectioninpolio does
not appearhampermg the operation, as proved by successful

With recognition of this unprecedented achievement ofsmallpox eradication, WHO and intemational community

thought of the next step,and agreed to strengthen immuniza‑

surveillanceinFAHOand WpRO.
AsofJanuary 2000,thereare all together 22 endemic statestion programs of vaccine preventable diseases. Thus,

reporting polio wild vims and 8 states where the vims

Expanded Programof lmmuniZation (EPI) corrmenced earlytransmission is strongly suspected due to lack of adequate

Sollrα: Polio Badication:wnO
JaA. 2(X氾

Fig. I. Stabs ofpolio eradication.

7

surveillanceand its proximityto endemic states. Theyarein
ABica,the Middle Eastand SoutheastAsia (Fig. 1). The situa‑

148 polio laboratories being engagedinsurveillance activities

tion is compared withthat of smallpox eradication. In smallpox(Table 3). Ofthese, I I 0 laboratories were accredited by WHO.
Such global effortsare commendable, but polio programmay

eradication programin 1970, 7 years before the last case,wish to limitthe number whenthe end is near.

there were 17 states where smallpox virus transmission was

continuing (Table 1). In other words, the current situation ofpolio eradication,the number of endemic or suspected polio
states is larger thanthat of smallpox eradicationinthe year

Discu ss io tI

Why weare, flrSt Of all, specificallyinterestedinthe lengthof 1970. If the target year of2000 were to be met, these aof an eradication program.

total of 30 states should finish the transmission from now

As discussedinthe Eradication Conference, heldinBerlin
in1 997,the cost‑benefit of eradication programdepends upon

until December 2000 (Fig. 1), namely, kom now on, only 12months.

its lengthoferadication program, namely ̀他e longerthe global

Further, if we make the observation one year before thelast case in smallpox eradication, the number of states

program, the greater the expenditureandthe lesser the
benefit"(2). For example, Northand SouthAmerica became

reporting the virus was only two, Kenyaand Somalia. Kenya

free of polio in 1991and Westem Pacificin1997･ Though

had only importation; Somalia had an extensive outbreaks

this is commendable achievement, they must continue sur‑

newly developed being lmPOrtedfrom Ethiopia. The extent

veillance as well as immunization programas long as polioof resourcesinvestment was comparedinbothsituations. In

remains endemicinIndianSubcontinentand A斤icanConti‑

smallpox eradication,inabout 40 million popuhtion areas, 45

nent.

WHOpersornel were asslgned for the special containment

We would note,there is a sbiking similaritybetween small‑campalgn in addition to the nationwide mobilization ofnational staff(Table 2). In polio eradication, there appears topox eradication and polio eradication program in tens of
the endemic states making "fast" progressandthose making

be about 200intemational staff worldwide, roughly for I 500
million population in 30 statesinAtiicaandAsianConti‑

cation was ht launchedin1958. Allthe 59 states ofsmallpox

Hslow" progress.Asmentioned previously, smallpox eradi‑

endemic were recomended to conduct vaccination programs.

nent.

hthe last stage of smanpox eradicadon, notably die numberof laboratories was strictly limited to efficientand reliable
ones, Centers for Disease Control and Prevention (CDC),
Atlantaand Research Institute of ViralPreparation (RIVP),

Moscow, bothwere WHO Intemational Collaboration Center

In about 12 yearS'time, statesinLatinAmerica as well asin
Westem Pacific became endemic smallpox Bee. Thus, theIntensified Rogramdealt withthe 3 1 endemic states of sub‑SaharanA飢ca, hdianSubcontinent,and Indonesia (Fig. 2).

for diagnosis of smallpox. The measures were particularly

In polio eradication, it had been stark,dfrom 1985inSouthand North America,and globally from 1988. Similarly in

critical sincethere was no room to make mistakeinthat very

about 12 yearS'time, "fast" statesinLatinAmerica as well aslast stage of the globalprogram. This wasina sensean
extreme action, butthere wastheunderstanding thatinthe
emergency situation, WHO could not afford to let limited
number of programstaffwork for improvement of laboratory
capabilityatthat time. h polio eradication,thereare at present

Westem Pacific became endemic Bee. And since 1995, theglobal programwas dealing withendemic states, so to speak
HslowM states,insub‑SaharanABicaand withthoseinhdian
Subcontinent. Parenthetically, Egypt and Iraq made fast
progress in smallpox eradication, b山only slow progress inpolio eradication, reason for which may need some studies･
Now血e question is "Can polio eradication program stop

Table 2. Estimated number of WHO personneland of laboratories forsmallpox eradication as of 1976‑1977

No. ofpersoTnel Population (Estimated in 1970)
RegionalOfrice
E仙iopi a

Subcontinent. Here, we should review dle Situationinsmallpox

3 ′0 5 1

eradication as previously mentioned･ There were 1 ) the U･S･

26 million

1 2Somalia

3 million

Kenya (importation)

1 1 million

Tota1

polio transmissionin2000?", or how nearthe end?
Since 1998, substantialefforts have been made to strengthen
the national programs n sub‑SaharanABica as well as Indian

45

40

bilateral CDC program with Headquarter (Hq) in Lagos,
Nigeriain19 states ofWestand Central Africa (1967‑1970)
withthe last caseinNigeriain1970, 2) Autumn Campaign

million(1973‑1975) in Indian Subcontinent with the last case ln
Laboratories to support surveillance are only 2 ‑ one in CDC, Atlanta and

Bangladeshin1975,and 3) Hom ofA飢ca Campaign (termeduCrocodile"inEthiopia) withthe world last endemic casein

the other in RJVP, Moscow.

1977. The number of personnel intemational as well as
national were certainly far greater Oanthose for cu汀ent POlio

Table 3. Type of laboratories for polio in JanuaJY 2000

WHORegiOnalOlrlCe 牌ﾆ
AFRO

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EMRO
EURO

SEARO

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eradication (when the number of personnelintemational aswell as nationalare available, it would be desirable to makecorrect comparison).

AsofJanuary 2000, polio eradication lS POSitioned where?
It would not be certainlythe position comparable tothe small‑pox eradication's 1976‑one yearbefore the world last case･

1

鼎B

4

2

Those "slow" statesinpolio eradication have some advan‑
tages over some endemic states during smallpox eradication,

2

鼎"

first, they have had experience in EPI programs during last15#r

1 5 years. Secondly,they should have a confidence they cando, if they want, having achievedthe great successinsmall‑148

pox eradicationinthe past･ Further vaccination apparently

POL10 ERADIGA10N｢駄陸｣.ida.口叫一
二∴∵.･.･:円舞

22 0rldomic AnJ 8 su叩●Ct StJteS⊂:::コ‑ Qr｡up a s･l｡ぬd d戒｡S hving如ppd th｡ hnqnission‑ Spco inJiCating A押rOXirnde y●■rS Of叩●raticn or叩OCiAl caTTIPIP

Fig･ 2･ Comparison: how states making progress in smallpox and polio eradications･is relatively effective to stop transmission in low densely

be fairand sensible for polio programtoindicate new target

populatedareas like sub‑SaharanA丘ica (3). How much these

yearof2002, at time ofWorld HealthAssembly (Wfh) 2000

things could acceleratethe progress meeting 2000 year target?
In smallpox eradication, massiveinvestment ofintemationaland national persormelinuslown states was cause of success0r of October 2000 when VVPRO declares the freedom ofpolioinpart ofAsianContinent. Inthis occasion, it is of vital
importance to request additional resources to flnish the job

as described before･ It should be notedthat althoughthe

up･diseases are different, managerial aspect of eradication global

This revision of target date needs courage. Though, nothingshould be the same.
Parenthetically,insmallpox eradication,the last epidemic
inthe Hom of Africa was,in fact, "set‑back". We were com‑

wrong,and politically solid. Once WHO said "Healthfor allplacent onincomplete surveillance capabilityintheseareas.
In polio eradication, politicalinstabilityappears to be worsepressing too much endemic states toward zeroincidence maylead to false surveillance results as happened in Iranand
Somalia duringthe last stage of smallpox eradication program.

by 2000"･ Without special notion,the phrase disappeared.
We should assure publicthat once we say, lt Will be so. Also,

thanthat 20 years ago･ EpidemicsinAngola was a good lesson･
Therefore, strengthening surveillance capabilitywould be also

What is the plan, then? The last acceleration period

top priorityin catching up･ We are not saying, the Hom ofrequires to conduct 1 ) cautiousand dispassionateanalysis of

A&ica would bethe last polio endemic area･ It could beany

prograpsinindividual polio endemic states,and 2) estimate

states where surveillance is poorand resulting contairmentof requlrementS for additional resources to be made available

isineffective.
These reviews may lead to concemthat the target 2000

in terms of persormel as well as contingency funds for field

and laboratory work.Whether or not the magnitude of(December 2000) may not be reached.Asmentioned before,

investment done by smallpox eradication campalgnS Shouldteclmically both programs should be feasible, but different
modus operandi makes one wonder how the polio program

be applied would be critical decision, but it is absolutely

certainthat substantialincreaseinintemationaland national

personnel will be needed to meet a new target year.Asdone

Peetsthe target･ It should be notedthat even withsuch greater
Investment the smallpox programhad enormous ditrlCulties
such as war, shortage offundingand extremely difrlCult

insmallpox eradication, a specialinformation ofrlCer alreadyrecmited would be important to deal with the world major

geographicalterranwhich required helicopters･ h all aspects,

presses.Whentheincidence goes downto some level, reward

it would be sensible to glVe additional three years as to meetarmouncement also canbe of help. This would preventthe target, based on the experience that the above mentioned

suppression of case reports. Provision of transport may needspecial eradication campaigns could eliminatethe foci roughly

special attention.Asdone by U.S. bilateralinWest A&icainin three years'time. We should stress that if the current

1 967‑ 1 970, JapanIntemational Cooperation Agency (JICA)

program met the targetin2002 (three years from now), it

would be still the second greatest achievement by WHOandprovided 257 vehicles to polio eradicationinChinain1990'S.
Any query byintemational communityshould be responded

by member states following Smallpox eradication. It would

promptly. Perhaps, prioritywill also have to be re‑examined9and determined with clearunderstandingthat the operational

states are commendable. The momentum, if intensified byprogramto "stop endemic transmission" should come first.
Smallpox programstaffsometimes brokethe WHOrule. Thismay be a lesson polio programshould "not" take.
Lastly, we should add,inthis discussion, we did not use
the number of reported cases. Instead, we used the ntmber ofendemic states. Because the varied surveillance capability
often leads to the confusing assessment of actual status of
disease transmission. Also, certification programwas not

additiohal mobilization of world resources, Would make theglobal program reach the endin2002. For global resource
mobilization, it would be rational strategy, namely Japan

together withother partners focus onAsian Continent and
U.S.and E.U. onAfrica.

Althoughthe delaythusOccurred, if succeeded, it would bea tremendoussuccess by humanity a洗er smallpox eradication,in the history of preventive medicine･ All the peopleunder
different civilizations will be beneflted.

mentioned, of which v九al p叩OSe is f♭r all WHO member

states to rest assumed that they cansafely disestablish thepolio immunization,andthis was not objective of this report.

AckJ10WIedgnebt
Although the report is to some extent a departure from

Measles Program

present WHO policy, wearethankful to Dr･ Bjom Melgaard

Discussion on measles eradication programhas started.
However, unless polio eradication is over, measles program
should be ofa low priority. It is noted thatinWPRO, former

and his staff members who have kindly provided valuable
information on current situation of global polio eradication.

Regional Director advised not to tak on measles elimination

Kyusyu Region, JapanTropical Medicine Congressand Dr･

We also thank Dr. 1払kezumi Yoshimtm, Regional President,

before achievlng Zero POliointhe Region. In fact,this was a

Tamotsu Kanazawa, President of Congress, for encouraglng

wisdom for the success. Sometimeinfuture,there will be a

us to preparethis report. The report was presented during the

global measles eradication program, lessons丘om smallpox

reg10nal congress, which was held on 22 January 2000 at theeradication as well asthis on‑gong polio eradication will be

Universityof Occupationaland EnvirorLmental Health, Japan･

useful.
REFERENCE S
Conchsion

1. The Economist (1999): The body: a dose of history.

Polio eradication is nowinprogress to interrupt the wild

December 31, 108‑109.
2. Arita, I. (1998): Are there better global mechanisms forformulating, 1mPlementing,and evaluating eradication

polio transmission globally. It aims to be by December 2000,
namely only one year le允 forthe completion of the program,when this report is being prepared.

programS? p･ 177‑I 86 In W･R･ Dowdleand D･R･ HopkinS

Experienceinspecial eradication campalgnS conducted by
the past smallpox eradication was used to assessand safe‑guard
the current progress of the global eradication. Such assessment
led to cautious thinking that additionalthree years would be
required to reachthe globalinterruption of transmission.
Considerable efforts so farmade by WHO as well as member(eds.), The eradication of infectious diseases. John Wiley& Sons, hc., New York.

3. Arita, I., Wickett, J.and Fenner, F. (1986): Impact of
population density on immuniZZltion programmes･ J･ Hyg･ ,96, 459‑466.

10