Progress Toward Poliomyelitis Eradication --- Egypt, 2002
Since the World Health Assembly resolved in 1988 to eradicate poliomyelitis globally, the number of countries in which polio is endemic has declined 94% from 125 countries to seven. The estimated number of wild poliovirus-positive cases worldwide has decreased >99%, and three World Health Organization (WHO) regions (Americas, European, and Western Pacific) are now certified as polio-free (1--3). Substantial progress has been made in the Eastern Mediterranean Region, where poliovirus is endemic in four (Afghanistan, Egypt, Pakistan, and Somalia) of 23 countries(4--6). This report summarizes progress during 2002 toward polio eradication in Egypt, where several independent chains of wild poliovirus type 1 (P1) transmission continue to circulate despite a long history of eradication efforts. The findings indicate that surveillance and vaccination activities have improved substantially and highlight the need for further improvements to interrupt poliovirus transmission.
Since 1994 reported routine vaccination coverage of infants with >3 doses of oral poliovirus vaccine (OPV) has remained >90%. During 2002, reported routine coverage was >95% nationwide; six (2%) of 247 districts reported levels <90%*.
Supplementary Immunization Activities (SIAs)
Egypt began implementing national immunization days (NIDs) in 1989. During 2000--2002, the number of NID rounds increased from two to three. Systematic house-to-house vaccinations were conducted, and the number of vaccination teams and supervisors increased. The high quality of these NID rounds was documented by independent monitors (WHO Eastern Mediterranean Regional Office, unpublished data, 2002). The number of children aged <5 years who were vaccinated increased from approximately 8.6 million during December 2001 to 9.8 million during December 2002. In addition, during March and April 2002, subnational immunization days§ (SNIDs) were held in Upper Egypt.
Surveillance for Acute Flaccid Paralysis
Surveillance for acute flaccid paralysis (AFP) was initiated in Egypt during August 1990. During 2002, surveillance performance improved substantially compared with 1998--2001 (Table). The national target level for AFP surveillance (i.e., >1 nonpolio AFP case per 100,000 children aged <15 years) has been reached each year since 1998. During 2002, AFP surveillance improved twofold; standardized operating procedures were established, polio officers designated at all administrative levels, and active surveillance conducted in all districts.
Stool samples collected from persons with AFP were tested at the national polio laboratory, which is accredited by WHO as a regional reference laboratory in the global poliovirus laboratory network. Since 1996, genetic sequence analyses have been performed routinely on all wild polioviruses detected in Egypt. Results indicate that all are related closely to poliovirus lineages that have been indigenous to Egypt for >7 years. The genetic sequence data also indicate decreasing genetic diversity of polioviruses and fewer lineages surviving in each successive low transmission season.
In July 2000, the Ministry of Health and Population (MOHP) began to supplement AFP surveillance with environmental surveillance (i.e., collecting and testing wastewater samples) for the presence of wild poliovirus. During 2001, samples were collected from 10 sites in seven governorates of Upper Egypt (Aswan, Asyut, Beni Suef, Fayoum, Minya, Qena, and Sohag) and from one site in Gharbia governorate in Lower Egypt. In 2002, environmental surveillance was expanded to include additional sites in Lower Egypt (Alexandria, Behera, Menofia, and Sharkia) and greater Cairo (Cairo, Giza, and Kalioubia). All environmental surveillance isolates underwent partial genomic sequencing, which indicated that the viruses were related closely to P1 detected through AFP surveillance. Genetic data indicated that a single genotype of P1 with multiple lineages has persisted in Egypt for >7 years. Poliovirus types 2 (P2) and 3 (P3) have not been detected by environmental surveillance.
During 2002, a total of 26 (16%) of 162 samples from 11 (73%) of 15 governorates tested were positive for P1, compared with 64 (57%) samples from all eight governorates tested in 2001 (Figure). During 2002, four (10%) of 41 samples from Lower Egypt, seven (70%) of 10 from greater Cairo governorates (except Kalioubia), and 15 (14%) of 107 from Upper Egypt tested positive for P1. No wild type poliovirus was isolated from the 13 samples from Minya in upper Egypt, an area that has sustained circulation for >10 years.
Wild Poliovirus Incidence
Since late 1999, AFP surveillance has detected wild poliovirus in several districts of Upper Egypt. P2 was last detected in Egypt in 1994, and P3 was last detected in December 2000. During 2001--2002, only P1 was isolated. During July--December 2002, seven wild poliovirus cases were detected, compared with 35 cases in 1998; six (86%) of these seven virologically confirmed wild poliovirus cases were detected in Lower Egypt and greater Cairo (Figure). All seven cases were reported after AFP surveillance was enhanced; six (86%) of the seven cases occurred in children aged <5 years who had received >2 doses of OPV during SIAs.
Reported by: Ministry of Health and Population; Regional Office for the Eastern Mediterranean Region, World Health Organization, Cairo, Egypt. Dept of Vaccines and Biologicals, World Health Organization, Geneva, Switzerland. Div of Viral and Rickettsial Diseases, National Center for Infectious Diseases; Global Immunization Div, National Immunization Program, CDC.
Although interruption of wild poliovirus transmission in Egypt has been delayed, surveillance and mass immunization campaigns have improved considerably since 2000. During 2002, the sensitivity and efficiency of AFP surveillance improved, and the nonpolio AFP rate increased approximately twofold. Immunization campaigns also have improved, resulting in more children aged <5 years receiving vaccine. Genetic data from isolated polioviruses indicate reduced genetic diversity and fewer lineages, both signs of progress.
During October--December 2002, three rounds of NIDs were conducted, covering the entire country for the first time in a house-to-house campaign, with intensified supervision and a substantial increase in the number of vaccination teams. The success of these NIDs reflects increased participation by government and nongovernment sectors and the implementation of a comprehensive communication and social mobilization plan. Approximately 1.2 million children aged <5 years who apparently were missed previously were vaccinated in these NIDs, highlighting the effectiveness of this strategy.
Improved surveillance has yielded a better overview of polio epidemiology in Egypt. The genomic data provided by the seven polio cases that were reported from Upper and Lower Egypt during July--December 2002 after approximately 1 year of no reported cases, and the increased number of AFP cases investigated, suggest that some polio cases had been missed previously.
Improved surveillance and vaccination reflect implementation of the recommendations of a technical advisory group (TAG) comprising international and national experts that was established in 2001. In 2002, TAG reviewed the available epidemiologic and programmatic information and recommended four actions: 1) establishing a system to give a financial reward to persons identifying AFP cases, 2) encouraging MOHP's call for transparency in reporting, 3) implementing active surveillance, and 4) targeting high-risk urban areas for improved house-to-house vaccination campaigns. In February 2003, TAG recommended that the two NID rounds planned for March and May 2003 proceed and that additional rounds be conducted in fall 2003. TAG will meet again later in 2003 to decide whether additional SIAs are needed.
For poliovirus transmission in Egypt to be interrupted, the partners involved in the polio eradication effort should sustain and extend the progress made to date. Improving the program further should be an ongoing part of Egypt's eradication program. Environmental surveillance suggests that polio cases are being missed in areas of Upper Egypt where polio is endemic. Sustained support from the Egyptian government and the commitment of financial and technical resources from MOHP and its partners are required to implement a comprehensive work plan developed by MOHP to carry out the TAG recommendations.
* Coverage calculated by dividing the number of OPV doses administered by the number of registered infants. This might result in an overestimation of coverage.
Mass campaigns over a short period (days) in which 2 doses of OPV are administered to all children in the target group (usually those aged <5 years) regardless of previous vaccination history.
§ Campaigns similar to NIDs but confined to part of the country.
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