Vol.3 N°25, Updated on 5 July 2017
Influenza Virological Surveillance in the WHO African Region Epidemiological Week 25, June 19 to 25, 2017
Editor Dr Ibramima Socé-Fall Director, WHE Programme
Editorial Board Dr B. Impouma Dr Y. Zabulon Dr M.D. Harouna Dr A.A. Yahaya
During epidemiological week 25, 13 laboratories (Burkina Faso, Central African Republic, Congo, Cote d’Ivoire, Ethiopia, Ghana, Madagascar, Mauritania, Mauritius, Mozambique, Senegal, South Africa and Togo) in the African region influenza laboratory network contributed data for analysis. During week 25, 84 specimens were positive for influenza out of the 387 that were tested (22% positivity rate). This is a decrease in the positivity rate from week 24 (29%). Influenza types and subtypes identified were influenza A/H3 (46/84, 55%), influenza A/H1 (1/84, 1%), influenza A/H1N1pdm09 (18/84, 21%) and influenza B (15/84, 18%). Four influenza A specimens remain untyped (5%). Cumulatively* from epidemiological week 1 to 25 the AFR influenza laboratory network has collected 16,500 and tested 15,531 specimens, of which 1,748 have been positive for influenza virus (positivity rate 11%). *adjusted for retrospective data.
Authors Dr. B. Herring Dr. S. Rajatonirina Mr. C. Massidi
Figure 1 – Weekly virological assessment of influenza specimens collected in the African region, weeks 1 to 25, 2017 1
Figure 2. Virological analysis of influenza specimens collected from weeks 1 to 25, 2017 in the African region
Eastern Africa: Burundi, Comoros, Eritrea, Ethiopia**, Kenya**, Madagascar**, Malawi, Mauritius**, Mayotte, Mozambique**, Rwanda**, Seychelles, Somalia, Uganda**, United Republic of Tanzania**, Zambia**, Zimbabwe
During epidemiological week 25, no data was reported from the Northern transmission zone. In the Eastern transmission zone 125 specimens were collected, 101 tested and 45 positives were identified (positivity rate 45%). Influenza types/subtypes identified were influenza type A/H3 (24/45), A/H1 (1/45), A/H1N1pdm09 (10/45) and influenza B (7/45). Three influenza A positive specimens remain untyped.
Western Africa: Benin, Burkina Faso**, Cape Verde, Côte d'Ivoire**, Gambia, Ghana**, Guinea, Guinea-Bissau, Liberia, Mali**, Mauritania, Niger**, Nigeria**, Senegal**, Sierra Leone, Togo**
Northern Africa: Algeria**
In the Western transmission zone all specimens collected (n=183) were tested for influenza of which 20 were positive. The positivity rate in the Western zone was 11%. Influenza types and subtypes identified included influenza A/H3 (6/20), influenza A/H1N1pdm09 (5/20) and influenza B (8/20). One influenza A specimen is yet to be typed. In the Southern transmission zone 19 positives were identified from the 58 tested (positivity rate 33%). Only influenza A was detected in this zone during the reporting week, subtypes detected were influenza A/H3 (16/19) and influenza A/H1N1pdm09 (3/19)(Figure 2).
Southern Africa : Botswana, Lesotho, Namibia, South Africa**, Swaziland
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In the Middle transmission zone no positives were identified from the 70 specimens collected and tested.
Middle Africa: Angola, Cameroon**, Central African Republic**, Chad, Congo, Democratic Republic of the Congo**, Equatorial Guinea, Gabon, Sao Tome and Principe
** Countries that report virological influenza data.
Regionally, influenza A (all subtypes) remains the predominant influenza type circulating (1141/1748, 65%), represented by influenza A/H3 (675/1141, 59%), A/H1 (1/1141, <0.1%) and A/H1N1pdm09 (374/1141, 33%) while 91 specimens remain untyped (8%). Influenza B represents 35% (607/1748) of circulating influenza types (Figure 4).
^ No data has been received from Northern transmission zone since week 12. * No positive specimens were recorded in the Southern transmission zone in Q1.
Figure 4. Influenza type and subtype distribution regionally and in the 5 transmission zones in the African region during weeks 1–13 (Q1) and weeks 1-25, 2017.
The information presented in this report are subject to change following completeness and verification Member States.
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