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2021 Virtual SA WPVA Congress Laura Roberts
THE AVIAN INFLUENZA SITUATION IN SOUTH AFRICA
20 April 2021
© Western Cape Government 2012 |
Overview
History
Ecology
Surveillance & testing
Current disease situation
• HPAI (H5N8)
• H6N2
• Other LPAI
Preparedness & planning
Avian Influenza in South Africa- L Roberts- April 2021 2
D Higgins, D Jordan USCDCP (pixnio.com)
Avian influenza virus
© Western Cape Government 2012 |
History
HPAI
1961- “Tern virus” (H5N3)
2004, 2006, 2011- H5N2 in ostriches
2017- clade 2.3.4.4 H5N8
• 6 genotypes
• Probably from West Africa
• Poultry & ostriches in 2017
• Coastal birds in 2018
LPAI (H6N2)
commercial chickens since 2002
Other LPAI
Avian Influenza in South Africa- L Roberts- April 2021 3
Unknown (2018)
Common tern
© Western Cape Government 2012 |
Ecology
Hosts & carriers
Isolated from 7/16 resident duck species (most common species)
Egyptian geese most risky (Cumming, 2008)
Also
Ibises
Charadriiformes (wader/ shorebirds, gulls & terns)
Passeriformes & Coraciiformes in Zimbabwe
All sorts with H5N8…
But our anatids don’t “migrate”
Relay transmission?
Virus from Eurasia and North America
Avian Influenza in South Africa- L Roberts- April 2021 4
L Roberts (2015)
Red-billed teal
© Western Cape Government 2012 |
Surveillance
Plans and protocols
Commercial PoultryNAI Contingency Plan (biannual)VPN 44/ HPAI measures
Backyard poultryNAI Contingency Plan• Provincial 6 monthly targets (min 50)
OstrichesNAI Contingency Plan (biannual)VPN4 • Pre-movement• Pre-slaughter• Post-movement
Wild birds…
Avian Influenza in South Africa- L Roberts- April 2021 5
© Western Cape Government 2012 |
Surveillance
Sample size calculation
n=30 (if N>900)
If…
All birds in the group have the same chance of being infected (= epi group)
Samples are taken randomly from the whole group
Test is perfect
So…
If virus/ antibody prevalence is ≥10%
95% “confident” (0.95 probability) will detect at least 1 positive
BUT not an accurate estimate of prevalence (1/30 positive ���� upper limit 95% CI= 17%
Avian Influenza in South Africa- L Roberts- April 2021 6
© Western Cape Government 2012 |
AI Testing in South Africa
Serology
ELISA (Influenza A)
HI (serotype)
PCR
Screening (matrix gene)
H5/7/6
Isolation
Genetic sequencing
Avian Influenza in South Africa- L Roberts- April 2021 7
L Roberts (2017)L Roberts (2017)
© Western Cape Government 2012 |
Current Situation
HPAI H5N8
Ostriches:
• Jan 2018 (PCR Oct 2019?)
• #219 Nov 2020 (serology)
• 8 “open” outbreaks
Poultry: June 2018 (Gauteng)
Wild birds: July 2018 (WC)
Avian Influenza in South Africa- L Roberts- April 2021 8
© Western Cape Government 2012 |
Current Situation
Viruses identified in ostriches since 2017
LPAI H5N2- Nov 2018, 2020
H11N1 (H11N9 mallards)- 2018, 2019
H9N2, H9N8- 2018, 2019
H6N2- 2019, 2020
LPAI H7(N1)- Aug 2020
https://www.elsenburg.com/vetepi/
Avian Influenza in South Africa- L Roberts- April 2021 9
© Western Cape Government 2012 |
Current Situation
H6N2
2 distinct antigenic sub-lineages- remained genetically pure
Vaccine based on sub-lineage I only- still effective but…
May have caused antigenic drift
Loss of ability to agglutinate chicken red blood cells reduces virus isolation
difficult to update PCR tests
Antigenic mismatch with HI test antigens results in false negatives
Ostriches: 5/5 H6 PCR neg, none H6 sero-pos
Poultry: some H6 HI reactions but few
Mutations linked to human receptor-binding
Avian Influenza in South Africa- L Roberts- April 2021 10
Haemahglutination test*
*BiotechMichael, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
© Western Cape Government 2012 |
Preparedness
National
Provincial
Industry/ company
Avian Influenza in South Africa- L Roberts- April 2021 11
© Western Cape Government 2012 |
Preparedness
Structure of Contingency Plan
Institutional Arrangements (Hierarchy)
WC Government AgricultureNational DAFF(Animal Health)Provincial Disaster Management & other departments
Communication protocol
Outbreak Management Logistics
Procurement
Record-keeping
Socio-economic considerations
Dept. Social Development/ Labour/ SASSA
Specific Disease Controls
Avian Influenza in South Africa- L Roberts- April 2021 12
© Western Cape Government 2012 |
Preparedness
Specific Disease Controls
Epidemiology- how the disease behaves- basic scientific facts
How to diagnose the disease (confirm outbreak)
Disease control
Human health precautions (PPE, involvement of Dept. Health/ NICD)
Quarantine and movement restrictions
Culling of infected animals (SPCA involved)
Disposal of carcasses & infected material (involvement of DEADP)
Cleaning and disinfection
Investigation of source/ cause
Resolution
Avian Influenza in South Africa- L Roberts- April 2021 13
© Western Cape Government 2012 |
Conclusion
AI is just a little bit complicated
AI surveillance and control is a team effort
Please do your part
Please be vigilant and ready
Avian Influenza in South Africa- L Roberts- April 2021 14
© Western Cape Government 2012 |
References
•Abolnik, C., 2020. Outbreaks of Clade 2.3.4.4 H5N8 highly pathogenic avian influenza in 2018 in the northern regions of South Africa were unrelated to those of 2017. Transbound. Emerg. Dis. 67, 1371–1381. https://doi.org/10.1111/tbed.13448
•Abolnik, C., Bisschop, S.P.R., Gerdes, G.H., Olivier, A.J., Horner, R.F., 2007. Phylogenetic analysis of low-pathogenicity avian influenza H6N2 viruses from chicken outbreaks (2001-2005) suggest that they are reassortants of historic ostrich low-pathogenicity avian influenza H9N2 and H6N8 viruses, in: Avian Diseases. pp. 279–284. https://doi.org/10.1637/7551-033106r.1
•Abolnik, C., Pieterse, R., Peyrot, B.M., Choma, P., Phiri, T.P., Ebersohn, K., Heerden, C.J. van, Vorster, A.A., Zel, G. van der, Geertsma, P.J., Laleye, A.T., Govindasamy, K., Rauff, D.L., 2019a. The Incursion and Spread of Highly Pathogenic Avian Influenza H5N8 Clade 2.3.4.4 Within South Africa. Avian Dis. 63, 149. https://doi.org/10.1637/11869-042518-Reg.1
•Abolnik, C., Strydom, C., Rauff, D.L., Wandrag, D.B.R., Petty, D., 2019b. Continuing evolution of H6N2 influenza a virus in South African chickens and the implications for diagnosis and control. BMC Vet. Res. 15. https://doi.org/10.1186/s12917-019-2210-4
•Becker, W.B., 1966. The isolation and classification of Tern virus: Influenza Virus A/Tern/South Africa/1961. J. Hyg. (Lond). 64, 309–320. https://doi.org/10.1017/S0022172400040596
•Cumming, G.S., Hockey, P.A.R., Bruinzeel, L.W., Du Plessis, M.A., 2008. Wild bird movements and avian influenza risk mapping in Southern Africa. Ecol. Soc. 13. https://doi.org/10.5751/ES-02536-130226
•Fusaro, A., Zecchin, B., Vrancken, B., Abolnik, C., Ademun, R., Alassane, A., Arafa, A., Awuni, J.A., Couacy-Hymann, E., Coulibaly, M.’. B., Gaidet, N., Go-Maro, E., Joannis, T., Jumbo, S.D., Minoungou, G., Meseko, C., Souley, M.M., Ndumu, D.B., Shittu, I., Twabela, A., Wade, A., Wiersma, L., Akpeli, Y.P., Zamperin, G., Milani, A., Lemey, P., Monne, I., 2019. Disentangling the role of Africa in the global spread of H5 highly pathogenic avian influenza. Nat. Commun. 10, 5310. https://doi.org/10.1038/s41467-019-13287-y
•Rauff, D., Strydom, C., Abolnik, C., 2016. Evolutionary consequences of a decade of vaccination against subtype H6N2 influenza. Virology 498, 226–239. https://doi.org/10.1016/j.virol.2016.08.035
Avian Influenza in South Africa- L Roberts- April 2021 15
Thank you
Tel: Fax:
www.elsenburg.com
Contact Us
Laura Roberts
State Veterinarian: Epidemiology (Program: Veterinary Services)
+27 808 5058