Progress Toward Poliomyelitis Eradication -- Afghanistan, 1994-1999
In 1988, the World Health Assembly adopted a resolution to eradicate poliomyelitis globally by 2000. During the same year, the Regional Committee, Eastern Mediterranean Region (EMR) of the World Health Organization (WHO) resolved to eradicate polio from the region by 2000. Substantial progress in reaching this goal has been made globally and in countries of EMR (1-3). This report describes the current status of polio eradication in Afghanistan, a country in EMR with ongoing civil conflict where eradication efforts began in late 1994.
Routine vaccination services have been maintained through approximately 20 years of civil conflict in Afghanistan. In 1996, estimated national coverage with three doses of oral poliovirus vaccine (OPV) among infants aged less than 1 year was 30%. Coverage surveys conducted during the 1998 Expanded Program on Immunization (EPI) review suggested that vaccination coverage levels varied widely by region. Coverage levels less than 30% were reported in several regions; in northern areas, coverage levels were even lower because of access problems resulting from the ongoing conflict. Supplemental campaigns to accelerate overall EPI coverage using diphtheria and tetanus toxoids and pertussis vaccine (DTP) and measles vaccine (MV) for children and tetanus toxoid (TT) for women of childbearing age have been conducted annually since 1997. The 1999 EPI acceleration campaigns provided catch-up vaccination to children aged less than 2 years (n=82,000) and women of reproductive age (n=206,000) in 14 urban areas.
Supplementary OPV Vaccination
Supplementary vaccination for polio eradication began with three multiantigen immunization campaigns (MICs) conducted during 1994-1996. MICs provided DTP, MV, and OPV for children aged less than 5 years and TT for women of childbearing age. Reported MICs coverage levels were greater than 80% in most targeted areas; however, MICs targeted approximately 70% of the total population. Beginning with MICs and continuing with National Immunization Days (NIDs)*, the United Nations Children's Fund (UNICEF) and WHO attempted to arrange periods of cease-fire between warring parties in conflict areas to allow vaccination of children.
The first NIDs were conducted nationwide during April-May 1997, and repeated during April-May 1998 and May-June 1999. In 1997, an estimated 80% of Afghan children aged less than 5 years (approximately 3.5 million) received two doses of OPV during NIDs.
In 1998, NIDs were not conducted in northern Afghanistan because of armed conflict; as a result, approximately one third of the target group was excluded from vaccination. Nevertheless, 1998 NID coverage for the accessible areas was greater than 85%. The first round of 1999 NIDs was delayed in three northern provinces because of the conflict; surveys following both rounds indicated that 83%-87% of targeted children had been vaccinated. Afghanistan will conduct two additional NID rounds in late October and November 1999. In 1998 and 1999, supplemental OPV vaccination campaigns were conducted in border districts with Pakistan and Iran simultaneously with the NIDs in these countries.
Surveillance for Acute Flaccid Paralysis (AFP)
No national disease surveillance system is in place in Afghanistan. In 1997, AFP surveillance was established at major health facilities in regional capitals. Local staff were trained in AFP surveillance procedures to conduct regular active surveillance visits to surveillance sites to identify and investigate AFP cases. Local offices of WHO and UNICEF facilitate the collection and shipment of stool specimens to the WHO Afghanistan support office in Islamabad, Pakistan through scheduled United Nations flights; specimens are forwarded for processing to the Regional Polio Network Laboratory at the National Institute of Health in Islamabad.
All three poliovirus serotypes were isolated within a few months after the establishment of AFP surveillance. Poliovirus has been detected in many parts of the country (Figure 1). All three serotypes were detected in 1997; however, type 2 virus has not been isolated during 1998 and 1999. Since May 1999, an outbreak of polio is occurring in Kunduz province in northern Afghanistan (4).
The sensitivity of AFP surveillance is measured by the rate of nonpolio AFP per 100,000 population aged less than 15 years (target: 1 per 100,000 population), and the quality is assessed by the percentage of cases from which two stool specimens are taken within 14 days of paralysis onset ("adequate" stool specimen; target: 80%). Both performance indicators continue to improve. From 1998 to 1999, the nonpolio AFP rate increased from 0.6 to 1.2, and the proportion of AFP cases with two adequate stool specimens increased from 52% to 61% in 1999 (Table 1).
Reported by: Afghanistan Country Office, World Health Organization, Islamabad, Pakistan. Eastern Mediterranean Regional Office, World Health Organization, Alexandria, Egypt. Vaccines and Other Biologicals Dept, World Health Organization, Geneva, Switzerland. Respiratory and Enterovirus Br, Div of Viral and Rickettsial Diseases, National Center for Infectious Diseases; Vaccine Preventable Disease Eradication Div, National Immunization Program, CDC.
Polio remains the leading cause of permanent disability in Afghanistan, a country with civil strife for approximately 20 years (5). Poliovirus transmission must be interrupted in Afghanistan both to prevent morbidity, mortality, and permanent disability and to reach the 2000 global polio eradication target.
Limited cease-fire agreements were effective between fighting parties during MICs and NIDs, allowing health-care workers to vaccinate children in areas with ongoing conflict. Since 1997, NIDs have achieved relatively high coverage rates among the target population; however, interruption of virus transmission in Afghanistan may take longer than in countries with well-functioning routine vaccination programs.
AFP surveillance systems require a well-coordinated and sustained effort to identify suspected cases; collect, store, and ship stool specimens; and collect, tabulate, and analyze data. Despite the prevailing conflict, AFP surveillance has improved rapidly in Afghanistan and is becoming the model for establishing AFP surveillance in other countries under difficult circumstances (6). Measles and neonatal tetanus case reporting have been added to the AFP surveillance system as a first step toward establishing an integrated communicable disease reporting system. Contributing to the success in establishing surveillance is the cooperation among national health services, WHO, UNICEF, and nongovernmental organizations and with resources provided by the international donors. Although the quality of AFP surveillance in Afghanistan is better than in other countries where polio is endemic, it must improve to better establish the degree of virus transmission and to target areas for supplemental vaccination activities.
Polio eradication activities, particularly NIDs, can play a key role in initiating and revitalizing health services in countries where conflict has damaged the infrastructure; the investment in vaccination may serve as an example to restore other basic health services in the country. As demonstrated in other countries, critical elements of the polio eradication strategies implemented in Afghanistan--political commitment, international partnerships, capacity for surveillance, and integration of preventive services--now serve as a platform for strengthening vaccination and other preventive health services. Social mobilization and additional resources available for polio eradication (i.e., cold chain equipment, training, and additional staff) may lead to increased awareness and use of routine vaccination services.
Continued public health efforts are essential to eradicate polio in Afghanistan. End-stage acceleration of polio eradication in Afghanistan will require extra rounds of NIDs and house-to-house vaccination activities to administer OPV, which will require substantial additional external funding**. In the final phase of polio eradication, increased efforts are necessary. Unless polio eradication succeeds even under the most challenging circumstances, polio will remain endemic in some countries, resulting in exportation of poliovirus into neighboring and distant polio-free areas, and delaying regional and global polio eradication.
* Mass campaigns over a short period (days to weeks) in which two doses of OPV are administered to all children in the target group (usually aged 0-4 years) regardless of previous vaccination history, with an interval of 4-6 weeks between doses.
** Polio eradication in Afghanistan is supported by the national government. External support is provided by global polio eradication partners, including Rotary International, UNICEF, WHO, and the governments of the United States, Great Britain, Denmark, Norway, Netherlands, Sweden, Luxemburg, Germany, and the European Community.
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TABLE 1. Surveillance for acute flaccid paralysis (AFP) and National Immunization Days (NIDs) coverage -- Afghanistan, 1997-1999
* September-December 1997.
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