Vol.3 N°28, Updated on 28 July 2017
Influenza Virological Surveillance in the WHO African Region Epidemiological Week 28, July 10 to 16, 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 28, 13 laboratories (Algeria, Cameroon, Central African Republic, Cote d’Ivoire, Ethiopia, Ghana, Madagascar, Mali, Mauritania, Mauritius, Senegal, South Africa and Zambia) in the African region influenza laboratory network contributed data for analysis. During week 28, 93 specimens were positive for influenza out of the 596 that were tested (16% positivity rate). This is a decrease in the positivity rate from week 27 (23%) and reflects decreasing activity in the Southern transmission zone. Influenza types and subtypes identified were influenza A/H1 (1/93, 1%), influenza A/H3 (71/93, 77%), influenza A/H1N1pdm09 (18/93, 19%) and influenza B (3/93, 3%). Cumulatively* from epidemiological week 1 to 28 the AFR influenza laboratory network has collected over 19,100 specimens and tested 18,122, of which 2 302 have been positive for influenza virus (positivity rate 13%). *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 28, 2017 1
Figure 2. Virological analysis of influenza specimens collected from weeks 1 to 28, 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 28, data was received from the Northern transmission zone however no specimens were collected or tested during this epidemiological week. In the Eastern transmission zone 74 specimens were collected, 59 tested and 14 positives were identified (positivity rate 24%). Influenza types/subtypes identified were influenza type A/H3 (12/14), A/H1N1pdm09 (2/14). In the Western transmission zone 202 specimens (215 specimens collected) were tested for influenza of which 14 were positive. The positivity rate in the Western zone was 7%. Influenza types and subtypes identified included influenza A/H1 (1/14), influenza A/H3 (1/14), influenza A/H1N1pdm09 (11/14) and influenza B (1/14). In the Southern transmission zone 65 positives specimens were identified from the 264 tested (positivity rate 25%). Influenza types detected in this zone during the reporting week included, influenza A/H3 (58/65), influenza A/H1N1pdm09 (5/65) and influenza B (2/65). (Figure 2).
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
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In the Middle transmission zone no positives were identified from the 71 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 (1632/2302, 71%), represented by influenza A/H3 (1113/1632, 68%), A/H1 (2/1632, 0.1%) and A/H1N1pdm09 (455/1632, 28%) while 62 specimens remain untyped (4%). Influenza B represents 29% (670/2302) of circulating influenza types (Figure 4).
Transmission Zone Regional Weeks 1-13 (Q1)
North
South*
East
West
Middle
Weeks 1-26 (Q2)
Weeks 1-28
Influenza viruses A/H1 A/H1N1pdm09 A/H3 A not typed B * 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 1-28, 2017.
The information presented in this report are subject to change following completeness and verification Member States.
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