The cost of tsetse control using ‘Tiny Targets’ in the sleeping sickness endemic forest area of Bonon in Côte d’Ivoire: Implications for comparing costs across different settings

Abstract

Background Work to control the gambiense form of human African trypanosomiasis (gHAT), or sleeping sickness, is now directed towards ending transmission of the parasite by 2030. In order to supplement gHAT case-finding and treatment, since 2011 tsetse control has been implemented using Tiny Targets in a number of gHAT foci. As this intervention is extended to new foci, it is vital to understand the costs involved. Costs have already been analysed for the foci of Arua in Uganda and Mandoul in Chad. This paper examines the costs of controlling Glossina palpalis palpalis in the focus of Bonon in Côte d’Ivoire from 2016 to 2017. Methodology/Principal findings Some 2000 targets were placed throughout the main gHAT transmission area of 130 km2 at a density of 14.9 per km2. The average annual cost was USD 0.5 per person protected, USD 31.6 per target deployed of which 12% was the cost of the target itself, or USD 471.2 per km2 protected. Broken down by activity, 54% was for deployment and maintenance of targets, 34% for tsetse surveys/monitoring and 12% for sensitising populations. Conclusions/Significance The cost of tsetse control per km2 of the gHAT focus protected in Bonon was more expensive than in Chad or Uganda, while the cost per km2 treated, that is the area where the targets were actually deployed, was cheaper. Per person protected, the Bonon cost fell between the two, with Uganda cheaper and Chad more expensive. In Bonon, targets were deployed throughout the protected area, because G. p. palpalis was present everywhere, whereas in Chad and Uganda G. fuscipes fuscipes was found only the riverine fringing vegetation. Thus, differences between gHAT foci, in terms of tsetse ecology and human geography, impact on the cost-effectiveness of tsetse control. It also demonstrates the need to take into account both the area treated and protected alongside other impact indicators, such as the cost per person protected.

The cost of sleeping sickness vector control in the Democratic Republic of the Congo

“…Including this cost would increase the overall cost by approximately 6%. 3, we look at the cost of the work in Yasa Bonga, compared to the costs calculated for the three other Tiny Target costed [17,31,32]. The cost comparisons vary greatly depending on which criterion used.…”

“…The lack of comprehensive, accurate geospatial data on tsetse fly habitats, along with limited information about the actual "transmission zones," the sites where people get bitten by infected tsetse, makes it challenging to identify locations where vector control could impact transmission. This requires geospatial modelling followed by on-site entomological surveys, but limited information is available on the complete actual cost of these preliminary evaluations [17,[30][31][32]. These knowledge gaps also make it challenging to develop a uniform vector control strategy or to determine the necessary "quantity" of vector control per square kilometer needed to halt transmission throughout the countries affected by the disease [19,38].…”

Towards the sustainable elimination of human African trypanosomiasis in Côte d’Ivoire using an integrated approach

“…The first three years (until December 2018) of the Bonon intervention has been described elsewhere [31,32] Source: Institut Pierre Richet, Openstreetmap.org A T0 entomological survey using unimpregnated Vavoua traps for capture was conducted in the two foci before the first deployment of Tiny Targets. This T0 survey made it possible, in addition to sensitising local communities, (i) to delineate the intervention areas, (ii) to characterise the tsetse populations (species, densities, distribution) and (iii) to determine the distribution of control devices to be deployed.…”

“…The first three years (until December 2018) of the Bonon intervention has been described elsewhere [31,32] to characterise the tsetse populations (species, densities, distribution) and (iii) to determine the distribution of control devices to be deployed. All traps were set for 48 or 96 hours and georeferenced using a GPS (Garmin 64®).…”

Therapeutic Efficacy of Orally Administered Nitrofurantoin against Animal African Trypanosomosis Caused by Trypanosoma congolense Infection

“…Moreover, it is difficult to reduce vector density and trypanosome prevalence by using only vector control measures, such as insect traps, insecticide spraying, and sterile insect techniques in wide endemic areas [ 9 ]. To overcome the difficulty of the traditional tsetse control strategy, in the current tsetse control projects, new effective tsetse capture traps were developed [ 10 , 11 , 12 ]. Furthermore, an integrated approach, involving the combination of a baseline survey, aerial and ground spraying of insecticides, insecticide-impregnated targets, and the mass trypanocide treatment of domestic animals, could achieve a tsetse/trypanosomosis-free area in Burkina Faso [ 13 ].…”