RESUMO
OBJECTIVE: This article summarises the progress made since the introduction of environmental surveillance in the African Region. METHOD: Country selection was based on the poor AFP performance indicators i.e. Non polio AFP rate and stool adequacy. It was recommended that any country not meeting the required indicators should consider environmental surveillance activity as an additional tool to support AFP surveillance. The sites selection considered proximity to the target population, the size of the population to be sampled and the sensitivity of the sampling site. RESULTS: One hundred and fifty three sites have been established in Africa since 2011. In 2011, Nigeria was first country to introduce environmental surveillance and currently with of 59 validated sites, followed by Kenya in 2013 validating and sampling 9 sites and Angola 4 active sites in 2014. In 2014, Cameroon introduced ES and 31 sites followed by Niger with 9 sites and Madagascar with 23 sites. Later in the same year, Chad introduced ES activity and 4 active sites were selected. In 2015 Senegal introduced 3 sites, Guinea and Burkina Faso introduced 4 sites each., and. In 2016, a total of 179 Sabins, 36 Sabin 2s, 196 non polio enteroviruses (NPEV) and 1 vaccine-derived polioviruses (VDPV) were reported in Nigeria. Cameroon and Chad isolated 14 and 4 Sabins and 72 and 40 NPEV respectively. In Madagascar a total of 39 Sabins, 11 Sabin 2s and 277 NPEV were isolated. In other countries a majority of NPEV were isolated (data not shown). CONCLUSION: This report describes the progress and expansion of environmental surveillance that contributed to the identification of polioviruses from the environment and the interruption of wild poliovirus transmission in the African Region.
RESUMO
Laboratory screening for the diagnosis of hepatitis B virus (HBV) infection in blood donors currently consists of testing for hepatitis B surface (HBsAg) antigen alone. The prevalence of isolated anti-HBc-IgM is not yet known in the semi arid region of Nigeria. The major objective of this study was to determine the sero-prevalence of antibody to hepatitis B core antigen (anti-HBc-IgM) and other infectious agent markers; HBsAg, HCV, HIV and Syphilis among blood donors in the North Eastern region of Nigeria. In a cross sectional study from October 2010 to January 2011, 266 blood donors were tested for the infectious disease markers using standard ELISA procedures as contained in the manufacturer's standard operating procedures. The prevalence of various infectious markers obtained were as follows: HBsAg (8.6%); anti-HCV (1.5%); HIV (2.6%) and anti-HBc-IgM(18.4%). There was a zero percent prevalence of Syphilis in this donor population. The proportion of isolated anti- HBc-IgM antibody obtained was 18.1%. Performance indices for HBsAg were as follows: Sensitivity (10.2%), specificity (91.7%), positive predictive value (PPV) (21.7%), Negative predictive value (81.9%), and efficiency (76.7%). The prevalence of anti-HBc- IgM antibody was higher among first time blood donors (21.4%), and in some ethnic groups. There is a high prevalence of isolated anti-HBc-IgM antibody among blood donors in Maiduguri. The sensitivity of HBsAg was found to be very low and as such many recent HBV infections may be missed during pre-transfusion screening. The use of anti-HBc-IgM screening as a mandatory pre-transfusion screening test is hereby advocated.
