Vol.3 N°41, Updated on 31 October 2017
Influenza Virological Surveillance in the WHO African Region Epidemiological Week 41, October 9 to 15, 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 41, 16 laboratories (Burkina Faso, Cameroon, Central African Republic, Cote d’Ivoire, Democratic Republic of Congo, Ethiopia, Ghana, Kenya, Madagascar, Mali, Mauritania, Mauritius, Mozambique, Sierra Leone, South Africa and Zambia) in the African region influenza laboratory network contributed data for analysis. During week 41, 124 specimens were positive for influenza out of the 525 that were tested (24% positivity rate). Influenza types and subtypes identified were influenza A/H3 (28/124, 23%), influenza A/H1N1pdm09 (62/124, 50%) and influenza B (33/124, 26%). One influenza A specimen remained untyped (1%). Cumulatively* from epidemiological week 1 to 41 the AFR influenza laboratory network has collected over 28,100 specimens and tested 27,101, of which 3,857 have been positive for influenza virus (positivity rate 15%). *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 41, 2017 1
Figure 2. Virological analysis of influenza specimens collected from weeks 1 to 41 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 41, 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 13 specimens tested positive for influenza virus of the 87 tested (92 collected). The positivity rate was 15%. Influenza types and subtypes identified included influenza A/H3 (7/13), influenza A/H1N1pdm09 (4/13). and influenza B (2/13). In the Western transmission zone 140 specimens were collected and tested for influenza, of which 19 were positive (positivity rate 14%). Influenza types and
Northern Africa: Algeria**
subtypes identified included influenza A/H3 (4/19), influenza A/H1N1pdm09 (12/19) and influenza B (3/19). . For epidemiological week 41, 113 specimens were collected and 112 tested for influenza
Southern Africa : Botswana, Lesotho, Namibia, South Africa**, Swaziland
in the Southern transmission zone, of which 15 were positive for influenza (positivity rate 22%). Influenza types and subtypes identified included influenza A/H1N1pdm09 (2/15) and influenza B (13/15). (Figure 2).
2
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 41, 186 specimens were collected and tested for influenza and 77 positives were identified (influenza positivity rate 41%). Once again an increase from the previous week (week 40, 48%). Influenza types and subtypes identified included influenza A/H3 (17/77), influenza A/H1N1pdm09 (44/77) and influenza B (15/77). One influenza A specimen remained untyped.
** Countries that report virological influenza data.
Regionally, influenza A (all subtypes) remains the predominant influenza type circulating (2769/3981, 70%), represented by influenza A/H3 (1914/2769, 69%), A/H1 (2/2769, <1%) and A/H1N1pdm09 (776/2769, 28%) while 77 specimens remain untyped (3%). Influenza B represents 30% (1212/3981) 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), weeks 1-39 (Q3) and weeks 1-41, 2017. The information presented in this report are subject to change following completeness and verification Member States.
3