Jpn. J. Infect. Dis., 55, 2002

Laboratory and Epidemiology Communications

Eradication of Poliomyelitis in Ethiopia: Virological andAcute Flaccid Paralysis Surveillance
Berhane Beyene Mentaye*, Oyewale Tomori1, Oywale Femi2, Almaz Gebere Senbet3
and Tilahun Woldemichael4
Polio Laboratory, Ethiopian Health and Nutrition Research Institute, P.O. Box 1242,
2
World Health Organization Country Office, P.O. Box 3069,
3Disease Prevention and Control Department, Ministry of Health of Ethiopia, P.O. Box 1242,
4Ethiopian Health and Nutrition Research Institute, P.O. Box 1234, Addis Ababa, Ethiopia and1
World Health Organization Africa Office, P.O. Box BE 773, Harare, Zimbabwe
Communicated by Hiroshi Yoshikura(Accepted July 17, 2002)
In Ethiopia, as in other Third World countries, poliomyelitis
is a major public health problem affecting mainly preschool
children (1).
A study conducted at a major pediatric hospital in Addis
Ababa demonstrated an increase in new cases between 1971
and 1981. Eighty-nine percent of the cases with residual
paralysis were 2-year-old children. There was no seasonalvariation. A study in 1979 involving over a quarter of a million
school age children in Addis Ababa indicated a prevalence of
2.7/1,000, with an estimated annual incidence of 7.8/100,000(2). Another study, conducted from February to July in 1993,
indicated that the prevalence among children aged 5-9 years
was 7.3/1,000 (3). Other school and institutional based studies
revealed a higher prevalence (4).
The key to evaluating the status of polio eradication is
combining epidemiological and laboratory investigations ofacute flaccid paralysis (AFP) among infants and children (5).
Table 1 shows AFP cases reported in 1998-2001 andvaccination history. One important criterion of proper AFP
surveillance is the minimum detection of at least one AFPcase among 100,000 children under 15 years of age. Given thatthe corresponding population is about 30 million in Ethiopia,
the number of expected AFP cases is 300.
The AFP surveillance indicators are shown in Table 2. From1997 to 2001, Ethiopia made remarkable progress. However,
the rate of collection of two stool specimens within 14 days
after onset of paralysis remains unsatisfactorily low.
Table 3 shows the record of specimens sent to National*Corresponding author: Fax: +251-1-774722, E-mail: Berhane12@yahoo.com

Reports from Amhara, Oromia, and Southern Nations nationalities were the majority due to their population size.

Table 1. Acute flaccid paralysis (AFP) cases reported in
1998-2001

95

Year

AFP cases

No. vaccination (%)

1998
1999
2000
2001

66
189
346
553

8 (12.1)
27 (22.7)
49 (15.6)
101 (18.5)

Jpn. J. Infect. Dis., 55, 2002
Table 2. Acute flaccid paralysis (AFP) Surveillance indicators, Ethiopia
ParameterTarget

Non polio AFP rate in children <15 y
Proportion of AFP cases with 2 stool specimens collected
within 14 days of onset of paralysis
Proportion of districts making monthly reports including
zero reports
Proportion of AFP cases investigated within 2 days ofnotification
Proportion of stool specimens arriving at national levelwithin 3 days being sent
Proportion of stool specimens arriving at the lab in goodcondition
Proportion of stool specimens from which non polio
enterovirus was isolated
Proportion of stool specimens for which lab results weresent within 28 days of receipt at the lab1997

1998

1999

2000

2001

0.1

0.3

0.280.71.680%

14%

12%

23%

45%

47%

100%

N.A.

N.A.

75%

73%

72%

80%

86%

91%

94%

84%

85%

80%

80%

56%

94%

99%

96%

90%

60%

84%

64%

93%

87%

10%

0%

11%

19%

13%

25%

80%

0%

4%

49%

81%

40%

N.A.: not applicable

Table 3. Laboratory data obtained in National Polio Laboratory, Ethiopian Health and Nutrition Research Institute in 1997-2001
Year

AFP
cases*

Stool
specimens

W1

1997
1998
1999
2000
2001

1466
189
344
553

965
208
623
1086

00131Wild typeW2 W30000000000S1S2S301314400128260111547

Sabin type
S1+S2 S1+S300046000220S2+S3

S1+S2+S3000412NPEV**
031236130

16*tested at laboratory**Non-polio enteroviruses

Table 4. Cases with wild-type poliovirus isolates and vaccine history
EPID

Age (sex)

Onset of paralysis
month/day/year

Interval (days)
to investigation

VaccinehistoryType

Residualparalysis

ORD-ESH-99-079
SOU-SID-00-026
SOU-HAD-00-204
AMH-NGN-00-217
SOU-KAT-01-006

11 m (F)
1.5 y (F)4.5 y (F)12 y (M)
2 y 8 m (F)10/13/1999
3/14/2000
10/28/2000
11/ 7/2000
8/ 1/2001

18
20
13
1115

Zero OPV
Zero OPV
3 OPV
Unknown
2 OPV

P1
P1
P1
P1
P1

Yes
Yes
Yes
No
Yes

Bedada, WHO data manager; National Polio Laboratory
personnel; and the personnel from the 11 regions and 71 zones
in Ethiopia, who are part of the polio surveillance system andprovided us with the original surveillance information. Theauthors would also like to thank the Japanese International
Cooperation Agency for support of research conducted in thePolio Laboratory, Ethiopian Health and Nutrition ResearchInstitute, since 2001.

Polio Laboratory, Ethiopian Health and Nutrition ResearchInstitute. In 1997, we received only nine stool specimens intotal from the Oromia and Addis Ababa regions. In l998, thestool specimen number increased to 65, owing to improved
AFP surveillance. In 2001, we received 1,048 stool specimens
derived from 553 AFP cases. The isolates were shipped toJohannesburg Regional Referral Laboratory for intra-typic
differentiation by probe hybridization and ELISA.
Table 4 shows a detailed description of five cases fromwhich wild-type polioviruses were isolated. The isolates were
all type 1. Three of these patients had not received oral poliovirus vaccine (OPV). Residual paralysis was observed in fourof the five patients. DNA sequencing at the Centers for Disease
Control and Prevention, Atlanta, Ga., USA, revealed that thewild-type isolates in 1999-2001 were not related to otherviruses isolated in neighboring countries or elsewhere. It is
unlikely that the virus was imported from outside. The lastcase was a child in Muda Gerama Kebele in Kedida Gamela
Woreda of the Kembata zone (southern part of Ethiopia).

REFERENCES
1. Cockbum, W. C. and Drozopov, S. G. (1970): Poliomyelitis
in the world. WHO Bull., 42, 405-415.
2. Kloos, H. and Zein, Z. A. (1996): The ecology of healthand disease in Ethiopia. Westview Press, 192-196.
3. Maru, M., Getahun, A. and Hoshna, S. (1988): Prevalenceof paralytic poliomyelitis in rural and urban populations
in Ethiopia: report of a house-to-house survey. Am. J.
Trop. Med. Hyg., 38, 633-635.
4. Deker, P. A. and G.-Abate, C. (1988): Prevalence ofresidual paralysis due to poliomyelitis in school children
in Addis Ababa. East. Afr. Med. J., 26, 133-138.

The authors thank Dr. Balcha Girma of the Epidemiology
Department; the AFP surveillance officers at WHO; Mr. Tesfaye
96Jpn. J. Infect. Dis., 55, 2002
5. Hull, H. A., Ward, N. A., Hull, B. P., Milstien, J. B. andde Quadros, C. (1994): Paralytic poliomyelitis: seasoned

strategies, disappearing disease. Lancet, 343, 1331-1337.

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