Vol.3 N°32, Updated on 24 August 2017
Influenza Virological Surveillance in the WHO African Region
Epidemiological Week 32, August 7 to 13, 2017
During epidemiological week 32, 11 laboratories (Burkina Faso, Cameroon, Central African Republic, Cote d'Ivoire, Ethiopia, Ghana, Mali, Mauritania, Mauritius, Senegal and Zambia) in the African region influenza laboratory network contributed data for analysis. During week 32, 22 specimens were positive for influenza out of the 244 that were tested (9% positivity rate). This represents over a 50% decrease on the positivity rate from week 31 (19%).
Influenza types and subtypes identified were influenza A/H3 (6/22, 27%), influenza A/H1N1pdm09 (13/22, 59%) and influenza B (3/22, 14%).
Cumulatively* from epidemiological week 1 to 32 the AFR influenza laboratory network has collected over 21,000 specimens and tested 20,047, of which 2, 649 have been positive for influenza virus (positivity rate 13%).
*adjusted for retrospective data.
Editor
Dr Ibramima Socé-Fall Director, WHE Programme
Editorial Board
Dr B. Impouma Dr Y. Zabulon Dr M.D. Harouna Dr A.A. Yahaya
Figure 1 – Weekly virological assessment of influenza specimens collected in the African region, weeks 1 to 32, 2017
1 Authors
Dr. B. Herring Dr. S. Rajatonirina Mr. C. Massidi
2 During epidemiological week 32, data was not received from the Northern or Southern transmission zones for analysis.
In the Eastern transmission zone 32 specimens were collected, 18 were tested and 1 positive was identified (positivity rate 6%). The positive specimen was influenza types/subtypes A/H3.
In the Western transmission zone 171 specimens (177 specimens collected) were tested for influenza of which 21 were positive. The positivity rate in the Western zone was 12%. Influenza types and subtypes identified included influenza A/H3 (5/21), influenza A/H1N1pdm09 (13/21) and influenza B (3/21). (Figure 2).
Figure 2. Virological analysis of influenza specimens collected from weeks 1 to 32, 2017 in the African region
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**
Southern Africa : Botswana, Lesotho, Namibia, South Africa**, Swaziland Eastern Africa: Burundi, Comoros, Eritrea, Ethiopia**, Kenya**, Madagascar**, Malawi, Mauritius**, Mayotte, Mozambique**, Rwanda**, Seychelles, Somalia, Uganda**, United Republic of Tanzania**, Zambia**, Zimbabwe
3
Middle Africa: Angola, Cameroon**, Central African Republic**, Chad, Congo, Democratic Republic of the Congo**, Equatorial Guinea, Gabon, Sao Tome and Principe
The information presented in this report are subject to change following completeness and verification Member States.
** Countries that report virological influenza data.
Regionally, influenza A (all subtypes) remains the predominant influenza type circulating (1921/2649, 73%), represented by influenza A/H3 (1325/1921, 69%), A/H1 (2/1921, <1%) and A/H1N1pdm09 (529/1921, 28%) while 65 specimens remain untyped (3%). Influenza B represents 27% (728/2649) of circulating influenza types (Figure 4).
Figure 4. Influenza type and subtype distribution regionally and in the 5 transmission zones in the African region during weeks 1–13 (Q1), weeks 14-26 (Q2) and weeks 1-32, 2017.
* No positive specimens were recorded in the Southern transmission zone in Q1.
In the Middle transmission zone during this epidemiological week 32, 55 specimens were collected and tested for influenza and no positive specimens were identified.
