Vol.3 N°39, Updated on 31 October 2017
Influenza Virological Surveillance in the WHO African Region Epidemiological Week 39, September 25 to October 1, 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 39, 16 laboratories (Burkina Faso, Cameroon, Central African Republic, Cote d’Ivoire, Democratic Republic of Congo, Ethiopia, Ghana, Kenya, Madagascar, Mali, Mauritania, Mauritius, Senegal, Sierra Leone, South Africa and Zambia) in the African region influenza laboratory network contributed data for analysis. During week 39, 128 specimens were positive for influenza out of the 569 that were tested (22% positivity rate). Influenza types and subtypes identified were influenza A/H3 (36/128, 28%), influenza A/H1N1pdm09 (28/128, 22%) and influenza B (64/128, 44%). Cumulatively* from epidemiological week 1 to 39 the AFR influenza laboratory network has collected over 27,100 specimens and tested 26,064, of which 3,746 have been positive for influenza virus (positivity rate 14%). *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 39, 2017 1
Figure 2. Virological analysis of influenza specimens collected from weeks 1 to 39, 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 39, no data was received from the Northern transmission zone.
Western Africa: Benin, Burkina Faso**, Cape Verde, Côte d'Ivoire**, Gambia, Ghana**, Guinea, Guinea-Bissau, Liberia, Mali**, Mauritania, Niger**, Nigeria**, Senegal**, Sierra Leone, Togo**
In the Eastern transmission zone 6 specimens tested positive for influenza virus of the 72 tested (82 collected). The positivity rate was 8%. Influenza types and subtypes identified included influenza A/H3 (1/6) and influenza B (5/6). In the Western transmission zone 274 specimens were collected and tested for influenza, of which 62 were positive (positivity rate 23%). Influenza types and subtypes identified included influenza A/H3 (26/62), influenza A/H1N1pdm09 (17/62) and influenza B (19/62). For epidemiological week 39, 129 specimens were collected and tested for influenza in the Southern transmission zone, of which 22 were positive for influenza (positivity rate 17%). Once again a decrease in positivity rate from the previous week (19%). Influenza types and subtypes identified included influenza A/H3 (3/22), influenza A/H1N1pdm09 (1/22) and influenza B (18/22). (Figure 2).
Northern Africa: Algeria**
Southern Africa : Botswana, Lesotho, Namibia, South Africa**, Swaziland
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Middle Africa: Angola, Cameroon**, Central African Republic**, Chad, Congo, Democratic Republic of the Congo**, Equatorial Guinea, Gabon, Sao Tome and Principe
In the Middle transmission zone during epidemiological week 39, 94 specimens were collected and tested for influenza and 38 positives were identified (influenza positivity rate 40%). This represents a sharp increase from week 38 (positivity rate 16%). Influenza types and subtypes identified included influenza A/H3 (6/38), influenza A/H1N1pdm09 (10/38) and influenza B (22/38). All influenza B specimens were from the Central African Republic.
** Countries that report virological influenza data.
Regionally, influenza A (all subtypes) remains the predominant influenza type circulating (2591/3746, 69%), represented by influenza A/H3 (1846/2591, 71%), A/H1 (2/2591, <1%) and A/H1N1pdm09 (667/2591, 26%) while 76 specimens remain untyped (3%). Influenza B represents 31% (1155/3746) of circulating influenza types (Figure 4).
* 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), weeks 14-26 (Q2) and weeks 1-39 (Q3), 2017.
The information presented in this report are subject to change following completeness and verification Member States.
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