1 figure, 1 table omitted
Since the World Health Assembly resolved in May 1988 to eradicate poliomyelitis,
the estimated number of polio cases globally has declined >99%. The number
of countries in which polio was estimated to be endemic decreased from 125
in 1988 to 10 in 2001, and three World Health Organization (WHO) regions (American,
European, and Western Pacific) comprising approximately 55% of the world's
population have been certified polio-free.1 Ethiopia,
Somalia, and Sudan have achieved the lowest levels of poliovirus circulation
since the polio eradication initiative began and are approaching interruption
of transmission. This report describes intensified polio eradication activities
in these countries during January 2001–October 2002, summarizes progress
made, and highlights remaining challenges. Continued political commitment
and financial support will be required to eradicate polio in these countries.
According to national estimates, 50% of children in Ethiopia aged <1
year received 3 doses of oral poliovirus vaccine (OPV3) in 2001. In Somalia,
where vaccination services are delivered through national and international
nongovernment organizations supported by WHO, the United Nations Children's
Fund (UNICEF), and other United Nations agencies, OPV3 coverage was an estimated
33% in 2001. In Sudan, officially reported OPV3 coverage increased from 65%
in 2000 to 71% in 2001. However, because of the lack of a routine vaccination
program in the conflict-affected areas of the southern part of the country,
WHO and UNICEF estimate actual total national coverage at 47%.
Supplementary immunization activities (SIAs) began in 1994 in Sudan,
in 1996 in Ethiopia, and in 1997 in Somalia.2- 4 SIAs
were intensified through house-to-house vaccination beginning in 1999 in Somalia
and Sudan and in 2000 in Ethiopia. During 2001-2002, at least two rounds of
National Immunization Days (NIDs)* were conducted in Ethiopia, Somalia, and
Sudan among children aged <5 years (total estimated target populations:
13.7 million, 1.3 million, and 7.0 million, respectively). In addition to
NIDs, countries conducted additional rounds of subnational immunization days†
(SNIDs) targeting high-risk areas and populations. In Ethiopia, SNIDs were
conducted in 21 zones and three subzonal areas in five regions of the country.
The criteria used to select these areas included previous isolation of wild
poliovirus, poor surveillance indicators, poor routine vaccination coverage,
below-optimal performance in previous campaigns, difficulty in obtaining access,
and shared borders with countries in which polio is endemic. Approximately
3.5 million children were vaccinated in these campaigns.
High-quality implementation of SIAs has occurred in Somalia and Sudan
despite continuing armed conflict in those countries. In Somalia, during lulls
in fighting, a "rapid access" SIA strategy has been implemented in which vaccinators
have worked independently to target small populations in a short time. In
Sudan, which has experienced civil war for 34 years, SIAs in areas controlled
by the government have been coordinated successfully with SIAs in areas in
the south not controlled by the central government. During 2000-2001, lulls
in fighting allowed implementation of SIAs for the first time in the Nuba
Mountains and southern Blue Nile areas of Sudan.
Since 2001, Ethiopia, Somalia, and Sudan have exceeded the WHO-established
target for a nonpolio acute flaccid paralysis (AFP) rate indicative of sensitive
surveillance (i.e., ≥1 per 100,000 population aged <15 years). These
countries did not meet the WHO target measure of adequacy of collected stool
specimens (i.e., ≥80%) in 2001, although Sudan has met this target in 2002.
In 2001, the nonpolio enterovirus isolation rate (target: ≥10%), a marker
of laboratory performance and the integrity of the reverse cold chain for
specimens, was 25% for Ethiopia, 17% for Sudan, and 16% for Somalia.
AFP surveillance in Ethiopia, Somalia, and Sudan is facilitated by staffs
comprising trained polio eradication officers. In Ethiopia, 19 staff members
are posted throughout the country. In Somalia, which has not had a functioning
central government since 1991, UNICEF and WHO have deployed 164 full-time
national and international staff in all districts to assist with surveillance
and SIAs. In Sudan, 44 persons have been deployed in the north and 230 in
the south, a large area lacking infrastructure and experiencing conflict.
In addition to polio eradication duties, staff conduct limited activities
in the surveillance of other vaccine-preventable diseases (e.g., measles)
and participate in the early-warning network for other major infectious diseases.
The last reported wild poliovirus–positive cases in Ethiopia and
Sudan occurred in January and April of 2001, respectively. Both polioviruses
were type 1. In 2000, Ethiopia reported 155 confirmed polio cases, three of
which were confirmed virologically, and Sudan reported 79 cases, four of which
were confirmed virologically. In Somalia, 96 cases were reported in 2000;
46 were confirmed virologically, 42 (92%) of which occurred in the capital
city, Mogadishu. In 2001, seven virologically confirmed cases were identified
in the heavily populated Mogadishu area (Lower Shabelle and Banadir). During
2002, three virologically confirmed cases have been identified in Somalia
(most recently in October); all of these cases occurred in the Mogadishu area
(Lower Shabelle, Middle Shabelle, and Banadir).
Country Offices for Ethiopia, Somalia, and Sudan, World Health Organization.
Polio Eradication Programme, Regional Office for the Eastern Mediterranean,
World Health Organization, Cairo, Egypt. Vaccines and Biologicals Dept, World
Health Organization, Geneva, Switzerland. Div of Viral and Rickettsial Diseases,
National Center for Infectious Diseases; Global Immunization Div, National
Immunization Program, CDC.
Since January 2001, substantial progress has been made toward polio
eradication in Ethiopia, Somalia, and Sudan. Ethiopia and Sudan have not reported
a polio case in >1 year, and transmission in Somalia appears limited to the
Mogadishu area. These achievements have been the result of substantial efforts
by the countries with the support of the international public- and private-sector
partnership for polio eradication.
Progress toward polio eradication in Somalia and Sudan demonstrates
that eradication strategies can be implemented successfully even in areas
with poor access and ongoing conflict. Cease-fire agreements have allowed
access to children previously unreached by health services. National capacity
has been strengthened to address other diseases by building disease reporting
and surveillance systems and by developing national human resources through
training. The program has developed a platform to provide countrywide health
services by establishing an extensive system to access children.
Key challenges to the eradication programs include improving the quality
of SIAs and surveillance. Countries classified as polio-free should maintain
high levels of polio vaccination coverage and surveillance to ensure interruption
of virus transmission and provide a barrier against virus importation. Program
activities should be strengthened in the Somali and Afar regions of Ethiopia
bordering Somalia; weak or absent health infrastructures in these regions
have resulted in low vaccination coverage and inadequate AFP surveillance.
Although reaching children in conflict-affected areas (including the Mogadishu
area) is difficult, access must be secured to interrupt wild poliovirus transmission.
The close collaboration between WHO and UNICEF, which has been of critical
importance in Somalia, should continue.
To enhance eradication activities, countries must provide the necessary
technical support and maintain political commitment as polio incidence declines
and attention turns to other pressing health needs. In April 2002, the Global
Technical Consultative Group for Poliomyelitis Eradication identified the
greatest challenge to polio eradication as securing the necessary financial
resources.5 To support continuing high-quality
polio eradication activities in Ethiopia, Somalia, and Sudan, WHO and UNICEF
will require an estimated $50 million in 2003.
Efforts to support polio eradication programs will continue. Independent
technical advisory groups will meet, and managerial reviews will be conducted
in each country to monitor progress and provide guidance. Before regional
certification of polio eradication, laboratory containment of wild polioviruses
must be achieved. WHO is assisting countries in developing and implementing
national plans for laboratory containment of poliovirus,6 and
the polio-free countries of Ethiopia and Sudan have begun the containment
process. Substantial trained personnel and infrastructure have been established
in Ethiopia, Somalia, and Sudan through polio eradication programs, particularly
in Somalia and Sudan; this infrastructure will be available after polio eradication
to address other important health issues, and planning will be needed to ensure
*Nationwide mass campaigns during a short period (days to weeks) in
which 2 doses of OPV are administered to all children (usually aged <5
years), regardless of previous vaccination history, with an interval of 4-6
weeks between doses.
†Mass campaigns similar to NIDs but in a smaller area.
Progress Toward Poliomyelitis Eradication—Ethiopia, Somalia, and Sudan, January 2001–October 2002. JAMA. 2003;289(9):1095–1097. doi:10.1001/jama.289.9.1095