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Progress Toward Poliomyelitis Eradication -- African Region, 1998-April 1999.

In 1988, the World Health Assembly resolved to eradicate poliomyelitis globally by 2000 [1]. To achieve this goal, the African Region (AFRO) of the World Health Organization (WHO) has accelerated polio eradication strategies [2,3], but the region remains one of the two major reservoirs for wild poliovirus transmission [4,5]. This report summarizes progress toward polio eradication from 1998 through April 1999 in AFRO, highlights supplementary vaccination activities (National Immunization Days [NIDs])[*] and acute flaccid paralysis (AFP) surveillance conducted in the region, and describes plans for program acceleration (intensified NIDs and mopping-up vaccinationst [+]) to meet the 2000 eradication target.

Supplementary Vaccination Activities

From 1998 through April 1999, two rounds of NIDs or Subnational Immunization Days (SNIDs) were conducted in 34 countries where polio is endemic or was recently endemic in AFRO except in Sierra Leone (one round) and Guinea-Bissau (no rounds). Approximately 88 million children received two doses each of supplemental oral poliovirus vaccine (OPV) in 1998. Two countries reported NID coverage of [less than]80% (Sierra Leone, 78%, and Gambia, 79%). Eighty-two percent of NID rounds had coverage of [grater than]90%. In the Democratic Republic of Congo (DR Congo), two rounds of supplemental vaccination (first round December 1998, second round January 1999) were conducted. The first round was in 125 of 307 health zones with 91% coverage. The second round was in 176 of 307 health zones with 92% coverage. In Angola in 1998, SNIDs were not conducted in 42 of 164 districts. However, coverage for the 122 districts reached by SNIDs was 91%.

Acute Flaccid Paralysis Surveillance

The number of reported AFP cases increased from 505 in 1997 to 1754 in 1998 (Table 1). In 1998, the nonpolio AFP rate was 0.3 cases per 100,000 children aged [less than]15 years. Wild poliovirus was isolated from 96 AFP cases from many countries of central and western Africa and Angola (Figure 1). The largest number of wild poliovirus cases were in western Africa (Nigeria [n=42], Ghana [n=18], and Cote d'Ivoire [n=1 11). Partial genomic sequencing of the viruses indicated intense transmission and rapid movement of polioviruses across countries in western and central Africa. A large outbreak of wild poliovirus type 3 is being investigated in Luanda, Angola (953 cases reported as of May 18, 1999) [6].

In 1998, no wild poliovirus was isolated from stool specimens from 209 of the 305 AFP cases in southern Africa and 235 of the 399 AFP cases in eastern Africa. Nonpolio AFP rates and/or adequate stool collection remained low (less than]0.5 per 100,000 children aged [less than]15 years or [less than]80% of AFP cases with two stool specimens collected within 14 days of onset of paralysis) in Kenya, Madagascar, Malawi, Mozambique, South Africa, Uganda, and Zambia. However, in 1999, AFP rates in Kenya, Uganda, and Zambia have increased considerably. No wild poliovirus was isolated from specimens submitted from Ethiopia and Mozambique, but in both countries the nonpolio AFP rate was [less than or equal to] 0.1.

Program Acceleration

To reach the 2000 target, AFRO recommends that Angola, Chad, DR Congo, Guinea-Bissau, Liberia, Niger, Nigeria, and Sierra Leone conduct intensified NIDs during 1999. Intensified NIDs occur when the vaccines are administered to all target-aged children in house-to-house outreach efforts and sometimes include a third round. DR Congo will be conducting three rounds from July through September 1999. Angola will be conducting three rounds, mostly house-to-house, from July through September 1999.

In 1999, mopping-up vaccinations already have been conducted in Bangui, Central African Republic, and have been conducted in Ougadougou, Burkina Faso, in May and June. In Nigeria, 13 million children in 15 of 37 states were targeted to receive OPV during house-to-house vaccination campaigns from April through May. Preliminary data from the first round indicate that house-to-house vaccination is reaching 10%--40% more children than the previous NIDs [7]. For 1999, AFRO is recommending that mopping-up vaccinations be conducted in one to four surrounding provinces if a single wild poliovirus is isolated in 1999 [greater than]60 days after the second round of the NIDs. Reported by: Expanded Program on Immunization, Regional Office for Africa, World Health Organization, Harare, Zimbabwe. Vaccines and Other Biologicals Dept, World Health Organization, Geneva, Switzerland. Respiratory and Enteric Virus Br, Div of Viral and Rickettsial Diseases, National Center for Infectious Diseases; Vaccine Preventable Disease Er adication Div. National Immunization Program, CDC.

Editorial Note: During the past 12 months, accelerated efforts to achieve polio eradication have occurred in Africa. These efforts include the first attempt at large-scale urban and rural supplementary vaccination in DR Congo, the first NIDs with nationwide coverage of [greater than]80% for both rounds in Nigeria, and NIDs in all countries where polio is endemic except Guinea-Bissau. In addition, the number of reported AFP cases increased approximately 400% in 1998 over 1997, reflecting improved surveillance.

Intense wild poliovirus transmission continues to occur in Angola, DR Congo, and western and central Africa. Because high-quality house-to-house vaccination campaigns helped eliminate wild poliovirus transmission quickly in other WHO regions, AFRO is recommending more house-to-house NIDs and SNIDs in countries where wild poliovirus transmission persists. In DR Congo, three rounds of NIDs are planned during a cease-fire negotiated by the United Nations. In Nigeria, mopping-up vaccination efforts in April and May 1999 are substantially larger than the house-to-house vaccinations that were conducted in the Americas or Western Pacific Region. Most ministries of health have accepted WHO'S recommendation for a more aggressive supplemental vaccination with house-to-house NIDs, mopping up, and extra rounds.

Indigenous wild poliovirus is virtually absent in southern and eastern Africa. The last wild poliovirus isolated in southern Africa was in 1993. The last wild polioviruses isolated in eastern Africa were in July 1996 in Tanzania, October 1996 in Uganda, and December 1995 in Zambia. AFP surveillance in Ethiopia and Mozambique is inadequate to determine wild poliovirus transmission. Although surveillance has improved within the last year, substantial progress is needed to increase the nonpolio AFP rate from 0.3 to the standard threshold rate of 1.0. Active surveillance methods are necessary for adequate surveillance, and infrastructure improvements in transportation and communications are necessary for better active surveillance. Ensuring adequate personnel and transport for the active surveillance teams in the remaining reservoir countries are essential to reach the target by 2000.

Civil conflict, economic decline, and the high burden of diseases related to human immunodeficiency virus in many countries have strained public health infrastructures, resulting in some countries in declining routine vaccination coverage and low health staff morale. In Angola, Chad, and DR Congo, poor roadways make house-to-house vaccination and surveillance difficult. In addition, low routine vaccination has resulted in low population immunity to poliovirus in Angola, DR Congo, Nigeria, and countries of western and central Africa. Establishing and maintaining AFP surveillance in Angola and DR Congo -- countries in ongoing conflict -- are especially difficult challenges. Unlike carrying out NIDs for which cease-fires have been negotiated for a week at a time twice a year, surveillance must take place throughout the year for several years. Despite these obstacles, an intensely focused effort to eliminate the last remaining reservoirs in Africa with extra rounds, house-to-house vaccination, and good surveilla nce, if adequately supported [ss], can reach the goal of polio eradication by 2000.

References

(1.) World Health Assembly. Global eradication of poliomyelitis by the year 2000: resolution of the 41st World Health Assembly. Geneva, Switzerland: World Health Organization, 1988 (resolution WHA 41.28).

(2.) Regional Committee for Africa. Expanded Program on Immunization: disease control goals, the countdown has started-resolutions of the 45th Regional Committee for Africa. Brazzaville, Congo: World Health Organization, 1995 (resolution AFR/RC45/R5).

(3.) Organization of African Unity. Yaounde declaration on polio eradication in Africa. In: Proceedings of the 32nd Ordinary Session of the Organization of African Unity meeting. Yaounde, Cameroon: Organization of African Unity, 1996; AHG/Declaration 1 (XXXII).

(4.) Hull HF, Ward NA, Hull BP, Milstein JB, de Quadros C. Paralytic poliomyelitis: seasoned strategies, disappearing disease. Lancet 1994;343:1331-7.

(5.) CDC. Progress toward global eradication of poliomyelitis, 1997. MMWR 1998;47:414-9.

(6.) CDC. Outbreak of poliomyelitis--Angola, 1999. MMWR 1999;48:327-9.

(7.) CDC. Progress toward poliomyelitis eradication--Nigeria, 1996-1998. MMWR 1999;48:312-6.

(*.) Nationwide mass campaigns over a period (days to weeks), in which two doses of oral poliovirus vaccine (OPV) are administered to all children in the target age group (usually aged [less than]5 years), regardless of previous vaccination history, with an interval of 4-6 weeks between doses.

(+.) Focal mass campaigns in high-risk areas during a period (days to weeks) in which two doses of OPV are administered during house-to-house visits to all children in the target age groups, regardless of previous vaccination history, with an interval of 4-6 weeks between doses.

(ss.) The polio eradication efforts in AFRO are supported by member countries and a coalition of partners, including WHO; United Nations Children's Fund (UNICEF); Rotary International; U.S. Agency for International Development; CDC; United Nations Foundation; and the governments of Canada, Japan, and the United Kingdom.

Performance indicators for acute flaccid paralysis (AFP) surveillance, by
country -- African Region of the World Health Organization, 1997-1998
                       1997
                                               % AFP
                                               cases
                       No.                     with       Confirmed
                    reported    Nonpolio     adequate       polio
Region/Country      AFP cases AFP rate [*] specimens [+] (wild virus)
Central
 Angola                15         0.24           0         15 ( 0)
 Cameroon              11         0.17          18%        21 ( 0)
 Central African
  Republic             12         0.19          18%        10 ( 8)
 Congo                  0          --           --            --
 Democratic
  Republic of Congo    24         0.11          50%        82 ( 3)
 Equatorial Guinea      0          --           --            --
 Gabon                  0          --           --            --
Western
 Algeria               65         0.50           0          0 ( 0)
 Benin                  4         0.08          75%         3 ( 2)
 Burkina Faso          12         0.19          25%         3 ( 2)
 Chad                   4         0.07          75%       326 ( 2)
 Gambia                 1         0.20           0          1 ( 0)
 Ghana                 35         0.42          46%        17 ( 2)
 Guinea                 3         0.09          33%         2 ( 0)
 Guinea-Bissau          1         0.20         100%         1 ( 0)
 Cote d'lvoire         11         0.11          36%         6 ( 3)
 Liberia                0          --           --            --
 Mali                   3         0              0          2 ( 0)
 Mauritania             5         0.50           0          5 ( 0)
 Niger                 12         0.14          33%        56 ( 5)
 Nigeria                5         0.01          20%       383 ( 1)
 Senegal               12         0.19          44%         5 ( 1)
 Sierra Leone           0          --           --            --
 Togo                   4         0.13          75%         2 ( 1)
Southern
 Botswana               4         0.57          75%         3 ( 0)
 Lesotho                1         0.11         100%         0 ( 0)
 Madagascar            12         0.17          25%        10 ( 1)
 Malawi                10         0.20          60%         2 ( 0)
 Mozambique             4         0.05           0          4 ( 0)
 Namibia                5         0.71          60%         2 ( 0)
 South Africa          63         0.28          55%         0 ( 0)
 Swaziland              2         0.50         100%         0 ( 0)
 Zimbabwe              42         0.82          21%         3 ( 0)
Eastern
 Burundi                0          --           --            --
 Eritrea                0          --           --         41 ( 0)
 Ethiopia              13         0.05          23%        19 ( 0)
 Kenya                 22         0.16          36%        14 ( 0)
 Rwanda                 1         0.03           0          0 ( 0)
 Tanzania              20         0.13          50%        10 ( 0)
 Uganda                60         0.48          29%        35 ( 0)
 Zambia                 7         0.13          43%         5 ( 0)
Total                 505         0.16          24%      1088 (31)


                      1998
                                                % AFP
                                                cases
                       No.                      with     Confirmed
                    reported     Nonpolio     adequate     polio
Region/Country      AFP cases    AFP rate     specimens (wild virus)
Central
 Angola                16          0.10          56%       7 ( 3)
 Cameroon              40          0.40          60%      16 ( 0)
 Central African
  Republic             59          3.30          41%       6 ( 2)
 Congo                  0           --           --          --
 Democratic
  Republic of Congo    21          0.10          52%      10 ( 0)
 Equatorial Guinea      0           --           --          --
 Gabon                  1          0.20         100%       0 ( 0)
Western
 Algeria               88          0.83          75%       0 ( 0)
 Benin                 15          0.30          67%       8 ( 3)
 Burkina Faso          12          0.10          50%       8 ( 4)
 Chad                  12          0.30          83%       4 ( 4)
 Gambia                 0           --           --          --
 Ghana                154          0.50          30%     112 (18)
 Guinea                 7          0.10          43%       4 ( 0)
 Guinea-Bissau          0           --           --          --
 Cote d'lvoire         71          0.40          42%      38 (11)
 Liberia                0           --           --          --
 Mali                  23          0.20          30%      14 ( 2)
 Mauritania             0           --           --          --
 Niger                 12          0.10          50%       8 ( 4)
 Nigeria              489          0.40          39%     312 (42)
 Senegal               17          0.20          53%      10 ( 2)
 Sierra Leone           3     [less than]0.10     0        3 ( 0)
 Togo                  10          0.20          60%       5 ( 1)
Southern
 Botswana               5          0.70          80%       0 ( 0)
 Lesotho                5          0.20          40%       3 ( 0)
 Madagascar            17          0.20          53%       6 ( 0)
 Malawi                28          0.50          79%       5 ( 0)
 Mozambique            16          0.10          56%       7 ( 0)
 Namibia               11          1.30          64%       2 ( 0)
 South Africa         167          0.40          13%     104 ( 0)
 Swaziland              5          1.30          60%       0 ( 0)
 Zimbabwe              51          0.70          43%      17 ( 0)
Eastern
 Burundi                0           --           --          --
 Eritrea                0           --           --          --
 Ethiopia              63     [less than]0.10    13%      55 ( 0)
 Kenya                123          0.10           8%     109 ( 0)
 Rwanda                 2     [less than]0.10     0        2 ( 0)
 Tanzania             127          0.40          48%      66 ( 0)
 Uganda                61          0.10          23%      46 ( 0)
 Zambia                23          0.40          39%       6 ( 0)
Total                1754          0.30          39%     933 (96)


(*.)Per 100,000 children aged [less than]15 years.
(+.)Two stool specimens collected at an interval of at least 24 hours
within 14 days of onset of paralysis and adequately shipped to the laboratory.
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Publication:Morbidity and Mortality Weekly Report
Geographic Code:60AFR
Date:Jun 25, 1999
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