Public Health Benefits from Livestock Rift Valley Fever Control: A Simulation of Two Epidemics in Kenya.

Tabitha Kimani,Bernard Bett,Margaret Ngigi,Tom Randolph,Esther Schelling,Samuel Fuhrimann

doi:10.1007/s10393-016-1192-y

Abstract

In controlling Rift Valley fever, public health sector optimises health benefits by considering cost-effective control options. We modelled cost-effectiveness of livestock RVF control from a public health perspective in Kenya. Analysis was limited to pastoral and agro-pastoral system high-risk areas, for a 10-year period incorporating two epidemics: 2006/2007 and a hypothetical one in 2014/2015. Four integrated strategies (baseline and alternatives), combined from three vaccination and two surveillance options, were compared. Baseline strategy included annual vaccination of 1.2–11% animals plus passive surveillance and monitoring of nine sentinel herds. Compared to the baseline, two alternatives assumed improved vaccination coverage. A herd dynamic RVF animal simulation model produced number of animals infected under each strategy. A second mathematical model implemented in R estimated number people who would be infected by the infected animals. The 2006/2007 RVF epidemic resulted in 3974 undiscounted, unweighted disability adjusted life years (DALYs). Improving vaccination coverage to 41–51% (2012) and 27–33% (2014) 3 years before the hypothetical 2014/2015 outbreak can avert close to 1200 DALYs. Improved vaccinations showed cost-effectiveness (CE) values of US$ 43–53 per DALY averted. The baseline practice is not cost-effective to the public health sector.

Highlights

Rift Valley fever (RVF) is an arthropod-borne viral zoonosis that primarily affects domestic ruminants, humans and some wild animals (OIE 2002, 2007)
The analysis was limited to RVF high-risk areas in pastoral and agro-pastoral (PAP) livestock systems in Kenya, and for a 10-year period covering two epidemics—the 2006/2007 and a hypothetical one assumed to occur in 2014/2015
YLDchronic 1⁄4 Incchronic Â Dwchronic Â Durationchronic; where Inc is the Incidence and DW is the disability weight To estimate disability adjusted life years (DALYs) lost during the 2006/2007 epidemic, the 13% IgM seroprevalence derived 185,000 human cases reported in Nguku et al (2010) were assumed to represent all RVF infections in the pastoral and agro-pastoral high-risk areas plus Kilifi district located in mixed farming systems

Summary

INTRODUCTION

Rift Valley fever (RVF) is an arthropod-borne viral zoonosis that primarily affects domestic ruminants, humans and some wild animals (OIE 2002, 2007). An intervention that costs less than three times the national annual per capita GDP is considered cost-effective, whereas one that costs less than once the national annual per capita GDP is considered highly cost-effective For zoonotic problems such as RVF, gains in human health arise from both animal and public health interventions. Examining costs and benefits at both levels and in particular benefits to public health sectors arising from animal interventions becomes important. Knowledge of distribution of benefits would inform animal control cost sharing between animal and public health sectors. This cost-effectiveness analysis (CEA) examines impacts of four livestock sector level RVF intervention strategies on public health and identifies those that offer highest benefits to the public health sector

METHODOLOGY

Ei Â IP ð2Þ

RESULTS

COMPLIANCE WITH ETHICAL STANDARDS