Economic analysis of Rift Valley fever

prevention and control options from a multi-

sectoral perspective in Kenya

Presented at the 13th conference of the International Society of

Veterinary Epidemiology and Economics (ISVEE), Maastricht,

Netherlands, 20-24 August 2012

T. Kimani1,4, E. Schelling2, M. Ngigi3, T. Randolph1 1 International Livestock Research Institute, Kenya 2 Swiss Tropical and Public Health Institute, Basel 3 Egerton University, Kenya 4 Food and Agriculture Organization of the United Nations, Kenya

Introduction: Rift Valley fever

• Mosquito borne viral zoonosis, Africa and Middle East

• Epizootics, every 3-15 years

• Last two outbreaks in Eastern Africa: 1997-98, 2006-07

• Higher than normal rainfall, prolonged flooding, after a prolonged

drought

• Mosquito to animals

• Infected animal and animal products to people

• Impacts: economy wide

• Livestock

• Mortality; morbidity; trade bans, control costs

• Public health

• Mortality, morbidity and control costs

13th ISVEE- Maastricht, Netherlands

Livestock demography

RVF impact

Control mesures

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Step 1:

Transmission (SEIR) Model:

(poster 08.74, MSc, Fuhrimann )

Step 3: Identification of

alternate prevention

strategies, simulation, by

farming systems, for high

risk areas (20.2/65 million

animals)

Objective: CBA (livestock sector) and CEA (public health) of RVF control options, period: 2006-2015, assumed outbreak in 2014/2015

Step 2:

Asses public health costs and

DALYs of 2006/2007 RVF-

(MSc Thesis- A. Bitek)

Step 4: CBA & CEA:

•Mortality (RVF and other)

•Milk loss (drought,

RVF(abortions and

reductions),other abortions

•RVF Market effects, control

costs, 2014/2015 DALYs

•Pastoral system

(13.5 m animals)

Approach:

Selected AH Strategies

Strategy

Inter-epidemic vaccination schemes

1=Enhanced Surveillance (+ vector)

1= Use of insecticides for Larval

1 =Pour-on insecticides for animal treatment

0= Baseline, 9 sentinel herds

0 = none 0 = none

S1-Baseline 0 0 0 0

S2 1 1 1 1

S3 2 1 1 1

S4 0 1 0 1

S5 1 1 0 1

S6 2 1 0 1

S7 1 1 0 0

S8 2 0 0 0

S9 0 0 0 1

S10 0 1 1 1

S11 0 1 0 0

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Based on current and past practices , involved technical consultations- closer to

reality

Strategies

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• Vaccination Schemes

• Baseline = 2008 – 2014, coverage 4-7% sheep and goats

only,

• Option 1 = 2 mass vaccinations 2012 (41-51%); 2013 (28-

33%); 4 species; ear tag & monitor 3 years

• Option 2 = 1 mass vaccination 2012 (41-51%); annual

vaccination of young animals only ( 6-11%); 4 species; ear

tag

• Enhanced surveillance from 2012, shorter reaction time (delay of 3

weeks from 6 weeks in 2007)

• Larvicidal –limited application; reduce infection pressure by 7.5%

• Pour-on treatments; 10% of susceptible animals (without ear tags);

3 applications; delay of 4 weeks; 6 weeks protection

Results: Simulated Infected Proportions

-

0.050

0.100

0.150

0.200

0.250

Pro

po

rtio

n i

nfe

cte

d

Prevention and Control Strategy

Cattle Sheep Goats Camels

None of the evaluated measures and assumed levels of application

would stop an RVF epidemic

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• 24 month Livestock producer losses-2006-07

US$ 225 Million RVF Milk loss

3% Drought and

other abortions milk loss

10%

RVF Direct mortality

5%

Drought and baseline mortality

82%

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RVF Market effects ( US$ 9.3 million)

RVF Outbreak containment (US$ 5.23million)

Estimated RVF Impacts 2014/2015

-

10,000,000

20,000,000

30,000,000

40,000,000

50,000,000

60,000,000

70,000,000

80,000,000

90,000,000

S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11

Millio

n U

S$

Prevention and Control Strategy

Losses Control costs

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Average annual impacts 2008 - 2015

-

10.00

20.00

30.00

40.00

50.00

60.00

S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11

Mil

lio

n U

S$

Prevention and Control Strategy

PV RVF losses PV other losses

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• 8 years:1 RVF outbreak, 3 droughts & 3 normal years

• RVF impacts are relatively lower,

• Likely to be overlooked in the on going resilience building livestock

development activities

Livestock sector: Incremental Benefits & Costs compared

-

1.00

2.00

3.00

4.00

5.00

6.00

7.00

S2 S3 S4 S5 S6 S7 S8 S9 S10 S11

US

$ (M

illio

n)

Prevention and Control Strategy

Incremental benefits (Saved losses) Incremental costs

Strategy S2 S3 S4 S5 S6 S7 S8 S9 S10 S11

BCR

2.2

3.3

0.4

2.0

3.2

3.7

5.2

1.5

1.0 -

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Human RVF risk sources

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Public Health Costs and CEA -on going

•4,035.6 DALYs

estimated for 06/07

outbreak

•Next step

•Adjust DALYs for

underreporting

•Quantify the human

RVF transmission

from a known number

of infected animals

•Estimate costs/DALY

averted

Additional analysis

• The other two farming systems

• Sensitivity analysis

• Apply Social Accounting Matrix to estimate

economy wide impacts of RVF under

different control strategies

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Conclusions

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• This analysis more or less show that unless control measures are

stepped up, the next RVF epizootic is likely to have devastating

impacts.

• The current baseline vaccination of 4-7% of small ruminants

would barely have any impacts on reducing magnitude

• Increasing vaccination coverage for all species would yield

significant reductions in outbreak magnitude

• RVF epidemics have significant impacts, but higher impacts are

attributed to other causes.

• Need for tools to address market level impacts e.g. food safety

credibility and safe slaughter systems.

Acknowledgements

Funding from the International Development Research Centre

(IDRC) via the Agriculture and Health Research Platform of CGIAR

CDC Kenya and the Kenya Medical Research Institute

Thank you for listening

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