title: Evaluation of two influenza surveillance systems in South Africa.
abstract: BACKGROUND
  The World Health Organisation recommends outpatient influenza-like illness (ILI) and inpatient severe acute respiratory illness (SARI) surveillance. We evaluated two influenza surveillance systems in South Africa: one for ILI and another for SARI.
  
  
  METHODS
  The Viral Watch (VW) programme has collected virological influenza surveillance data voluntarily from patients with ILI since 1984 in private and public clinics in all 9 South African provinces. The SARI surveillance programme has collected epidemiological and virological influenza surveillance data since 2009 in public hospitals in 4 provinces by dedicated personnel. We compared nine surveillance system attributes from 2009-2012.
  
  
  RESULTS
  We analysed data from 18,293 SARI patients and 9,104 ILI patients. The annual proportion of samples testing positive for influenza was higher for VW (mean 41%) than SARI (mean 8%) and generally exceeded the seasonal threshold from May to September (VW: weeks 21-40; SARI: weeks 23-39). Data quality was a major strength of SARI (most data completion measures >90%; adherence to definitions: 88-89%) and a relative weakness of the VW programme (62% of forms complete, with limited epidemiologic data collected; adherence to definitions: 65-82%). Timeliness was a relative strength of both systems (e.g. both collected >93% of all respiratory specimens within 7 days of symptom onset). ILI surveillance was more nationally representative, financially sustainable and expandable than the SARI system. Though the SARI programme is not nationally representative, the high quality and detail of SARI data collection sheds light on the local burden and epidemiology of severe influenza-associated disease.
  
  
  CONCLUSIONS
  To best monitor influenza in South Africa, we propose that both ILI and SARI should be under surveillance. Improving ILI surveillance will require better quality and more systematic data collection, and SARI surveillance should be expanded to be more nationally representative, even if this requires scaling back on information gathered.
authors.affiliation: Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom; Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Services, Johannesburg, South Africa.
authors.forename: Eric
authors.initials: E
authors.lastname: Budgell
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, United States and Influenza Program, Centers for Disease Control and Prevention-South Africa, Pretoria, South Africa.
authors.forename: Adam L
authors.initials: AL
authors.lastname: Cohen
authors.affiliation: Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Services, Johannesburg, South Africa.
authors.forename: Jo
authors.initials: J
authors.lastname: McAnerney
authors.affiliation: Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Services, Johannesburg, South Africa.
authors.forename: Sibongile
authors.initials: S
authors.lastname: Walaza
authors.affiliation: Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Services, Johannesburg, South Africa; Department of Science and Technology/National Research Foundation: Vaccine-Preventable Diseases, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Shabir A
authors.initials: SA
authors.lastname: Madhi
authors.affiliation: Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Services, Johannesburg, South Africa.
authors.forename: Lucille
authors.initials: L
authors.lastname: Blumberg
authors.affiliation: Department of Medicine, Pietermaritzburg Metropolitan Hospital Complex and University of KwaZulu Natal, South Africa.
authors.forename: Halima
authors.initials: H
authors.lastname: Dawood
authors.affiliation: MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Kahn
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, United States and Influenza Program, Centers for Disease Control and Prevention-South Africa, Pretoria, South Africa; CTS Global, Inc., Los Angeles, United States of America.
authors.forename: Stefano
authors.initials: S
authors.lastname: Tempia
authors.affiliation: Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Services, Johannesburg, South Africa; Zoonoses Research Unit, Department of Medical Virology, University of Pretoria, Pretoria, South Africa.
authors.forename: Marietjie
authors.initials: M
authors.lastname: Venter
authors.affiliation: Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Services, Johannesburg, South Africa; Schools of Public Health and Pathology, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Cohen
mesh_terms: D062665:Epidemiological Monitoring; D006801:Humans; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D007297:Inpatients; D010045:Outpatients; D012141:Respiratory Tract Infections / Q000453:epidemiology / Q000821:virology; D012621:Seasons; D018571:Sentinel Surveillance; D013019:South Africa / Q000453:epidemiology
references.citation: Lancet. 2012 Jun 9;379(9832):2151-61
references.pmid: 22579125
references.citation: Clin Infect Dis. 2010 Dec 15;51(12):1362-9
references.pmid: 21070141
references.citation: MMWR Recomm Rep. 2001 Jul 27;50(RR-13):1-35; quiz CE1-7
references.pmid: 18634202
references.citation: MMWR Recomm Rep. 2013 Sep 20;62(RR-07):1-43
references.pmid: 24048214
references.citation: Epidemiol Infect. 2013 Jan;141(1):212-22
references.pmid: 22417876
references.citation: Lancet Infect Dis. 2011 Mar;11(3):223-35
references.pmid: 21371656
references.citation: PLoS One. 2009 Dec 29;4(12):e8453
references.pmid: 20041115
references.citation: Emerg Infect Dis. 2013 Nov;19(11):1766-74
references.pmid: 24209781
references.citation: J Infect Dis. 2012 Dec 15;206 Suppl 1:S14-21
references.pmid: 23169960
references.citation: J Infect Dis. 2012 Dec 15;206 Suppl 1:S159-65
references.pmid: 23169964
references.citation: J Infect Dis. 2012 Dec 15;206 Suppl 1:S1-4
references.pmid: 23169953
references.citation: Am J Emerg Med. 2012 Nov;30(9):1796-803
references.pmid: 22633701
references.citation: Euro Surveill. 2009 Oct 22;14(42):
references.pmid: 19883549
references.citation: PLoS One. 2011;6(5):e20111
references.pmid: 21637856
references.citation: Lancet Respir Med. 2013 Sep;1(7):574-84
references.pmid: 24461618
references.citation: PLoS One. 2015 Jun 15;10(6):e0129173
references.pmid: 26076197
references.citation: Bull World Health Organ. 2012 Nov 1;90(11):804-12
references.pmid: 23226892
references.citation: J Infect Dis. 2012 Dec 15;206 Suppl 1:S153-8
references.pmid: 23169963
references.citation: BMC Infect Dis. 2010 Nov 07;10:320
references.pmid: 21054897