the avian influenza situation in south africa

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


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


Unknown (2018)

Common tern


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


L Roberts (2015)

Red-billed teal


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…



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%



AI Testing in South Africa

Serology

ELISA (Influenza A)

HI (serotype)

PCR

Screening (matrix gene)

H5/7/6

Isolation

Genetic sequencing


L Roberts (2017)L Roberts (2017)


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)



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/



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


Haemahglutination test*

*BiotechMichael, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons


Preparedness

National

Provincial

Industry/ company



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



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



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



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


Thank you

Tel: Fax:

www.elsenburg.com

Contact Us

Laura Roberts

State Veterinarian: Epidemiology (Program: Veterinary Services)

+27 808 5058

[email protected]

the avian influenza situation in south africa

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