Foot and mouth disease situation and control strategies in sub-saharan Africa the current situation

Transcription

1 Foot and mouth disease situation and control strategies in sub-saharan Africa the current situation Wilna Vosloo CSIRO Livestock Industries, Australian Animal Health Laboratory (AAHL), Geelong, Australia

2 Introduction FMD is widespread throughout Africa Endemic in many countries Controlled in southern and northern countries Attitudes to control differ based on various factors Access to export markets Financial constraints and other priorities Political will Unrest By 2010 Africa may account for nearly two-thirds of the undernourished people in the world (USDA study)

3 Introduction The 7 serotypes are defined due to lack of cross protection Based on epidemiology, Africa has its own FMDV Unique SAT types More genetic and antigenic variation Wildlife maintenance hosts with apparent co-evolution New genetic and antigenic FMDV variants are generated Unclear role of other cloven-hoofed wildlife in spreading and maintaining the disease Various epidemiological patterns Involvement of wildlife Primarily livestock involvement

4 Summary of FMD status in Africa Pool 5 SAT1, SAT2, O, A Domestic cycle Pool 4 SAT1, O, SAT2, A Wildlife and domestic cycle Pool 6 SAT1,2,3 Mainly wildlife, increasingly domestic Adapted from WRL website

5 Outbreaks of FMD recorded since

6 Control actions in Africa Endemic countries No actions Limited vaccination Limited movement control Free countries Zoning Vaccination (routine and emergency) Movement control (permits, fencing) Stamping out

7 Evidence of increased number of FMD outbreaks Summary of outbreaks in South Africa since 2000 Previous outbreak in FMD-free region 1957 and in control zone 1983 Since 2000: 6 outbreaks in cattle 2000 SAT-1 and O 2001 SAT SAT SAT SAT-3

8 Evidence of increased number of FMD outbreaks Summary of outbreaks in Botswana outbreaks mixed SAT-1 and SAT-2 outbreaks 1980 SAT SAT SAT SAT SAT SAT-2 Recently a SAT-2 outbreak in Angola

9 KNP/9/03/Ribye-Waterhole KNP/1/06/2/Masakosa KNP/06/03/Shangoni SAR/2/04/Selwana-farm SAR/15/04/Dzumeri SAR/11/01/Craigieburn KNP/31/95 KNP/07/88 KNP/19/89 KNP/32/92/Boyela KNP/5/91/Satara SAR/1/03/Masisi ZIM/08/94 MAL/01/03 MAL/1/ ZIM/12/02/Chipinge ZIM/13/02/Chipinge ZIM/6/03/Harare ZIM/4/03/Harare ZIM/7/03/Chinhoyi MAL/3/75 MAL/01/04/Malawi ZAM/9/93 ZAM/10/93 ZAM/7/96 BOT/31/98/Vumbura NAM/4/07/Caprivi SWA/4/89 ZIM/10/02/Bikita 98 ZIM/01/01/Bulawayo ZIM/01/02/Beitbridge BOT/13/02 BOT/4/06/2 BOT/5/06/2 ZIM/34/90 ZIM/267/98/Chizarira ZIM/7/95/Sengwa NAM/01/92 08/467/Kavango/Namibia BOT/18/98 BOT/1/98/Nxaraga NAM/286/98 ZIM/08/02/Lupane ZIM/07/83/Nyamandlovu ZIM/4/88 ZIM/42/97 ZIM/48/97 SAU4/00 Malawi SAT outbreak 10% different from 2003 strain Kindly provided by R. Dwarka, TADP, OVI 0.05

10 KNP/5/06/2/Nwambi block KNP/4/Dzombo KNP/160/91 KNP/9/03/Ribye-Waterhole KNP/1/06/2/Masakosa KNP/39/Boyela KNP/05/03/Lower-Sabie KNP/6/96 KNP/1678/98/Bume KNP/06/03/Shangoni KNP/15/Bububu KNP/23/Shingumeni KNP/22/Shingumeni KNP/26/Shingumeni KNP/30/Langtoon Dam SAR/15/04/Dzumeri SAR/16/04 KNP/141/91 KNP/32/92/Boyela SAR/01/01/Mhala-district KNP/18/95 KNP/07/88 KNP/19/89 SAR/2/03/Masisi KNP/04/03/Punda-Maria MAL/3/75 MAL/01/04/Malawi MAL/01/03 ZIM/13/02/Chipinge ZIM/1/03/Harare-South ZIM/5/03/Harare ZIM/6/03/Harare ZIM/9/03/Harare ZIM/10/03/Chinhoyi ZIM/4/03/Harare ZIM/7/03/Chinhoyi ZAM/9/93 ZAM/7/96 BOT/31/98/Vumbura ZIM/09/02/Bikita NAM/4/07/Caprivi ZIM/01/01/Bulawayo BOT/13/02 ZIM/01/02/Beitbridge BOT/4/06/2 BOT/5/06/2 ZIM/16/91/Matusadona ZIM/01/00 ZIM/34/91 ZIM/14/90/DomaSafariarea ZIM/20/90 NAM304/98 08/467/Kavango/Namibia NAM/01/92 NAM/286/98 NAM/292/98 BOT/18/98 ZIM/06/02/Lupane ZIM/07/83/Nyamandlovu ZIM/2/88/Hwange ZIM/4/88 ZIM/4/97 ZIM/48/97 UGA/08/02 SAU6/00 Namibia SAT 2 Dec % difference between outbreak strains Aug 2008 Kindly provided by R. Dwarka, TADP, OVI 0.05

11 To control FMD in the face of increasing integration of landuse, we need to understand the behaviour of SAT viruses in domestic animals and wildlife and how FMD is transmitted from wildlife to livestock

12 Role of African buffalo in the epidemiology of FMD in southern Africa The 3 SAT serotypes are maintained by African buffalo (Syncerus caffer) that can be a source of infection for susceptible livestock in close proximity Buffalo can maintain FMDV for up to 5 years in a single animal FMD viruses change during persistent infection and may give rise to new antigenic variants

13 Features of the interaction between buffalo and the SAT type viruses Mode of transmission between buffalo and susceptible animals is not known, but there are 2 theories childhood infection in young calves sexual transmission Evidence of sexual transmission from persistently infected buffalo is tenuous Incidence of new infections with a single SAT type FMDV in a herd of 500 buffalo (using a stochastic simulation model) 35 No. of newinfections in the herd Years

14 Role of other wildlife species in FMD persistence and spread Species/animal Duration of viral persistence Domestic animals: Cattle Sheep Goats 2.5 to 3.5 years 9-12 months 2-3 months Wildlife: Wildebeest (Connochaetes taurinus) Sable (Hippotragus niger) Eland (Taurotragus oryx) Fallow deer (Dama dama) Kudu (Tragelaphus strepiceros) Water buffalo (Bubalis bubalis) African buffalo (Syncerus caffer) 28 days 28 days 32 days 63 days days 2-24 months 5 years

15 SAR/3/71 Cattle SAR/8/71 Impala SAR/2/71 Cattle SAR/12/71 Impala SAR/10/71 Impala 79 SAR/11/71 Impala SAR/4/81 Impala SAR/5/81 Impala SAR/2/73 Impala SAR/1/73 Impala SAR/4/74 Cattle 82 KNP/3/86 Buffalo 86 KNP/10/86 Buffalo KNP/20/89 Buffalo 64 KNP/3/89 Buffalo KNP/39/89 Buffalo KNP/196/91 Buffalo* KNP/8/89 Buffalo KNP/15/89 Buffalo 67 KNP/1/87 Buffalo KNP/2/96 Buffalo SAR/6/75 Cattle 65 SAR/30/74 Impala 91 SAR/25/74 Impala SAR/5/75 Cattle SAR/23/74 Impala SAR/26/74 Impala SAR/29/74 Impala 89 MOZ/3/77 Cattle SAR/9/81 Impala* SAR/4/79 Cattle 84 SAR/17/80 Cattle KNP/26/89 Buffalo KNP/4/89 Buffalo KNP/6/86 Buffalo 65 KNP/14/95 Buffalo KNP/17/95 Buffalo BOT/25/98 Buffalo 91 BOT/37/98 Buffalo ZIM/2/94 Buffalo 93 ZIM/3/88 Buffalo 91 NAM/272/98 Buffalo BEC/1/48 Cattle SAR/13/61 Cattle 96 BOT/2/98 Buffalo BOT/14/98 Buffalo BOT/8/98 Buffalo BOT/1/68 Cattle BOT/24/77 Cattle 68 BOT/1/77 Cattle BOT/17/77 Kudu ZIM/2/91 Buffalo ZIM/3/95 Buffalo MAL/1/85 Buffalo ZAM/2/93 Buffalo 97 ZAM/18/96 Buffalo UGA/1/97 Buffalo Role of impala in FMD epidemiology in KNP, SA Outbreaks in impala are derived from buffalo herds Impala can be a source of infection to domestic animals I 78 Serological survey indicated subclinical infection II III

16 Factors that impact on FMD prevalence in impala Risk factors Summer and autumn were highest risk factors for seropositivity, but clinical infection were mostly observed at the end of the dry season More females and adults were sero-positive Animal and herd behaviour Herds remain as relatively stable, discrete entities Although their home ranges may overlap to some extent, contact occurs most frequently at focal drinking points (if the herds occur away from perennial water) and not during grazing Impala are a sedentary species with small home ranges, and contact with other herds of impala on the rangeland is infrequent Breeding herds groom, male groups don t Disease spread relatively slowly in contrast with intensively farmed livestock

17 Factors that impact on FMD prevalence in impala Ecological factors Suitable grazing Water points (rivers versus drinking points) Impala:buffalo densities > ratio the more likely contact would be Factors influencing contact will impact on transmission Models would be needed for different ecological regions and for different wildlife species

18 Molecular epidemiology of FMD in Africa For all serotypes occurring in Africa, geographically distinct genotypes / topotypes occur SAT-2 demonstrates the most genetic variation with numerous topotypes Viruses evolve in distinct genotypes when no animal movement occurs Phylogenetic relationships indicate movement between various regions of Africa The genetic and antigenic variation have implications for vaccination policies

19 TUNISIA MORROCCO JORDAN ISRAEL ALGERIA LYBI A EGYPT SAUDI ARABI A MAURITANIA NIGER MALI SENEGAL GUINEABISAU SAT-2: YEMEN CHAD GAMBIA SIERRALEONE Topotype I Topotype II Topotype III LIBERIA SUDAN BURKINA FASO GUINEA COTE D IVOIRE B E N I GHANA N ERITREA TOGO NIGERIA ETHIOPIA CENTRAL AFRICAN REPUBLIC CAMEROON SOMALIA EQUATORIAL GUINEA GABON UGANDA CONGO ZAIRE KENYA RWANDA BURUNDI Topotype IV Topotype V TANZANIA Topotype VI Topotype VII ANGOLA Topotype VIII ZAMBIA Topotype IX Topotype X Topotype XI ZIMBABWE NAMIBIA BOTSWANA SWAZILAND Topotype XII Topotype XIII Topotype XIV LESOTHO SOUTH AFRICA

20 Within and between topotype variation indicates the need for various vaccine strains Chart to indicate the r-values of various SAT-2 isolates 1.2 I II 1 V 0.8 r-value IV ZIM 7/83 antiserum VIII IX KNP 19/89/2 antiserum ZIM 7/83 and KNP 19/89/2 antiserum (I) i (I) (I ) i (I) i (I) (I) ( I) (II) (II) (II) (II) (II) (I I) IV) V) III) (IX ) b ( b b b ( b V b b c 2 /2 /2 c /2 c c 2 c c ( 9 c 2 /2 89/2 1/2 92/2 93/2 /91 /91 83 / / /8 2/ 3 /9 5/ 51/ 7/ /88 /9 0 /94 /89 /91 03/2 /91/ 1/2 9/ / N P 1 P P 8 1/0 N G G N Z IM IM M N N A M P I A L M N K K K P KE Z ZI Z A H W NA A N KN S G W M K R Virus and topotype

21 Potential impact on FMD control by Transfrontier Conservation Areas The establishment of TFCAs Pressure to remove fences Human encroachment into wildlife areas Increased wildlife migration Introduction of novel FMD virus topotypes and impact on vaccines

22 Conclusions Challenges for FMD control remain and are on the increase Regional collaboration is increasingly important Improved vaccines will be the mainstay for control Vaccination of wildlife species Other options to improve exports should be investigated Commodity based trade Certification schemes Epidemiology of FMD in wildlife species need in depth investigation Role of small stock should be clarified

23 Acknowledgements OIE for the invitation All the staff at the TADP at the ARC-OVI Francois Maree, Belinda Blignaut, Pamela Opperman, Livio Heath, Rahana Dwarka, Brenda Botha, Nontobeko Mtshali, Jan Esterhuysen, Armanda Bastos Funding: Intervet, DoA, RMRDT, FAO, IAEA State veterinary services PhD and MSc students Mesfin Sahle, Oumou Sangare