Assessment of acute flaccid paralysis surveillance performance in East and Southern African countries 2012 - 2019

Introduction: polio eradication initiatives started in 1988, this is almost the past 32 years following the WHA resolution 41.8 of eradicating polio by the year 2000. As of 2019, only 3 countries remained to be polio endemic globally, Afghanistan, Pakistan and Nigeria. The east and southern sub-region countries had shown progressive achievement towards polio eradication and to start with the African regional certification. The availability of sensitive AFP surveillance performance is among important strategies in the achievement of polio eradication. We, therefore, decided to conduct this assessment of AFP performance from 2012 to 2019 in the ESA sub-region have evidence documentation and support the certification process of the WHO AFRO region. Methods: we reviewed all reported acute flaccid paralysis (AFP) cases from 19 countries in the ESA sub region with the date of onset of paralysis from 1 January 2012 to 31 December 2019. The data were run to descriptive analysis based on the personal characteristics and AFP surveillance performance indicators parameters. Results: a total of 46,014 AFP cases were reported from 19 countries in the ESA countries who were paralyzed from 1 January 2012 to 31 December 2019. The most affected age group was children aged 0 to 3 years old where 19,740 children with acute paralysis were reported representing 42.9% of the total reported AFP for the period. The overall assessment of the non-polio AFP rate, there is an increase from a rate of 2.7 in 2012 to 3.5 in 2019 per 100,000 population aged less than 15 years, reflects a significant change with a p-value of 0.040 (95% C.I. ranges from 0.035 to 1.564). Furthermore, the percentage of stool adequacy raised from 86.4% in 2012 to 88.5% in 2019, with an observed 2.1% difference and no significant change over the 8 years. Conclusion: we observed an overall increase in the sensitivity of the AFP surveillance performance for the ESA sub-region countries from 2012 to 2019 using the national performance indicators. The COVID-19 pandemic paused an operational challenge for AFP surveillance performances from 2020. A further subnational surveillance performance analysis is suggested.


Introduction
Polio eradication initiatives started as early as in 1988 when the fortyfirst world health assembly (WHA) sat in Geneva, from 2 to 13 May and came up with resolution WHA 41.8 for global polio eradication by the year 2000 [1]. The milestones for poliomyelitis eradication were initially revised in 2002 and further later in 2012 to accommodate unexpected challenges which were met on the implementation process [2,3]. Following the revision of milestones, tremendous efforts towards polio eradication were made. Even though it is over past 30 years ago, the incidence of polio has dropped by more than 99.99%, from about 350,000 cases a year in 125 countries yet there were 175 paralytic wild polio-virus type 1(WPV1) in 2019 from Afghanistan and Pakistan and three remaining polio-endemic countries: Afghanistan, Nigeria and Pakistan [4,5]. The last country in East and Southern Africa to report paralytic polio caused by wild polioviruses was Ethiopia in 2014 from importation [6]. Though significant progress has been made and observed over years, the last mile of polio eradication seems to be hardest especially since 2018 where paralytic polio cases increased from 22 in 2017 to 33 in 2018 and 175 in 2019 coupled with insecurity challenges, ebola outbreaks and COVID-19 pandemic [5,7,8].
The three polio endemic countries, Afghanistan, Nigeria and Pakistan they are all challenged by insecurity and some areas are not reached by immunization and surveillance programs. Furthermore, extensive environmental surveillance have been initiated around the world to supplement AFP surveillance and in the East and Southern Africa sub region where by December 2019 was already being implemented in 9 countries [9,10]. The use of adaptive innovative surveillance strategies such as electronic surveillance and geographical information system platforms provided surveillance information and intelligence against security threats and made polio eradication easier, more accountable, more focused/targeted and effective than in the previous years, studies evidence in Nigeria, Liberia, Papua New Guinea and other many countries to mention few [11][12][13][14]. The available evidence is supporting that poliomyelitis will remain to be the second disease to be eradicated globally even though the pathway had more programmatic and strategic program environment huddles than it was for smallpox eradication.
The African region has been free of wild poliovirus for over three years period and therefore is progressing towards regional certification.
Nevertheless, the emerging of circulating vaccines derived poliovirus (cVDPV) type 2 and 3 in the 14 countries of the 47 in the region including countries with accessibility challenges especially security compromised areas. This wave of cVDPV epidemics, in 2018 and 2019, is occurred in the high-risk countries of the African region which include almost half of the target population including Nigeria, DRC, Angola, Cameroon, Niger, Ethiopia, Mozambique, Kenya, Ghana, CAR Benin, Togo and Cote d'Ivoire [5,[15][16][17]. Only one of the twenty countries in East and Southern Africa had a less sensitive surveillance system to convince the African regional certification commission to accept their polio-free claim certification documentation before the end of 2019. This was contributed by the continuous sub-optimal AFP surveillance performance in the country mainly because of the security challenges, poor infrastructure and weak/fragile health systems.
Nonetheless, tremendous progress has been observed with the implementation of adaptive surveillance strategies to improve the situation. Irrespective of having sufficient information and best practices to share yet there is limited systematic AFP surveillance performance documentation in the ESA sub-region. We, therefore, decided to conduct this assessment of AFP performance in ESA subregion for the necessary evidenced documentation and may also be used to support the certification process of the WHO AFRO region. This AFP surveillance documentation will also provide additional information for decision-makers and partners on the AFP surveillance for the improved actions especially in the important last mile for polio eradication.  [19,20]. Nevertheless, validation of reported AFP cases was reported to be done by surveillance officers [21]. In every reported where 57% of the reported AFP were men and women were only 43%.

Methods
Even though of the slightly observed sex variation between men and women of the reported AFP cases in percentage there is no statistical significance, a p-value of 0.99 (95% C.I. ranges from -10.02 to 9.98).
The most age group reported to present as AFP was children aged 0 to 3 years old where 19,740 children with acute paralysis were reported representing 42.9% of the total reported AFP for the period (Table 1). The mean age with AFP for the period was 5.79 years with standard deviation of +5.17 years. Few adults (1.8%) were also investigated as AFP based on the medical clinical description of presenting symptoms of poliomyelitis disease and 12.2% of the reported AFP their age was not recorded in the reviewed database.
Regarding the symptoms, the commonest presentation was the lower limbs paralysis representing 84% (ranges from 76.4% to 89.2%) of the total reported AFP for the period, and 75.8% (ranges from 72.6% to 78.5%) presented with fever.
The asymmetrical paralysis occurred in 4% (ranges from 1% to 8%) of the reported AFP cases over the period. In the 8 years of AFP surveillance evaluation, many AFP cases were reported in 2016 (6,537 cases) and few were reported in 2013 (4,624 cases). We also found out, three countries Kenya, Lesotho and Malawi had a low average of non-polio AFP rate of less than 2.5 per 100,000 population aged less than 15 years compared to the other remaining 16 countries for the period between 2012 to 2019 (Table 2) It was also shown that an average of 96.2% of all reported AFP cases, the first and second stool samples were collected in an interval of 24 to 48 hours apart, ranging from 95.3% in 2017 to 99% in 2019 (Table   4). Furthermore, it was also noted that an average of 0.6% of all reported AFP cases the first and second stools were collected in 1 day this ranges from 0.2% in 2019 to 0.9% in 2017. We also realized there was a wider interval between the collection of first and second stool We also observed an increase in the number of three or more OPV doses received by the reported AFP cases from 65% (2012) to 81% (2019) indicating a significant difference a p-value of < 0.0001 (95% C.I. ranges from 0.147 to 0.172), the overall average for the period was 71%. Furthermore, we observed a reduction of AFP cases with unknown doses from 19% in 2012 to 6% in 2019 ( Figure 1).

Discussion
We observed that over 8 years period, from January 2012 to The site of paralysis in the AFP cases remained to be an area of concern for the clinician's knowledge because most them only consider paralysis of lower or upper limbs in contrast to the reality that paralysis can occur in any muscle. We, therefore, suggest focused training and sensitization should clearly explain this and consideration to revise AFP cases posters and ensure it includes paralysis of any muscle as defined in the standard case definition. We found out that the overall reported AFP surveillance performances for ESA countries This reflects the contribution of the effects of weekly feedback to countries for the improved surveillance decisions, community AFP surveillance and the use of innovative adaptive surveillance strategies such as AVADAR [13,14].
However, the implementation of AVADAR in some countries remained to be a challenge and may not be an optional strategy to maintain early notification as the strategy is expensive. Furthermore, the system may harm other community surveillance systems because of its motivation benefits which are not embedded in other surveillance systems. We also realized some of the first and second stool specimens were collected within 24 hours in contrary to the guideline that should be in an interval of 24 to 48 hours apart. This is an area again which we understand needs to be well communicated to countries for the quality sensitive surveillance system. Nevertheless, this is among the key AFP surveillance indicators that are being monitored weekly. In this study, it was revealed that AFP stool samples delivery was delayed in reaching the polio laboratories from the collection of second stool samples in the period for an average of 13%. This was thought to contribute negatively to the stool specimens' condition as the result of the reverse cold chain breakdown at any point. We also observed missing data as a challenge for almost all the variables involved in the AFP surveillance operations. This calls for the country's data managers' commitments for the data cleaning.

Conclusion
We observed an increase in the AFP surveillance performance for the What this study adds  The study identifies weaknesses and progress and recommends ways of improving surveillance performances to achieve regional certification and beyond;  The study provides valuable information on the trend of acute flaccid paralysis surveillance performance for the ESA countries for eight years compared to Africa regional and global polio surveillance standards;  The study indicates the need for countries in ESA to focus to the sub-national/district surveillance gaps and good performing countries to avoid complacency in this last mile for polio eradication.

Competing interests
The authors declare no competing interests.