A Test-and-Not-Treat Strategy for Onchocerciasis Elimination in Loa loa–coendemic Areas: Cost Analysis of a Pilot in the Soa Health District, Cameroon

Lenk, Edeltraud J.; Moungui, Henri Claude; Boussinesq, Michel; Kamgno, Joseph; Nana-Djeunga, Hugues C.; Fitzpatrick, Christopher; Peultier, Anne-Claire M. M.; Klion, Amy D.; Fletcher, Daniel A.; Nutman, Thomas B.; Pion, Sébastien; Niamsi-Emalio, Yannick; Redekop, William K.; Severens, Johan L.; Stolk, Wilma A.

doi:10.1093/cid/ciz461

Cited by 13 publications

(13 citation statements)

References 15 publications

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“…[21] Urban and semi-urban areas show consistently lower rates of participation. [5,21] The rationale of getting tested for safe treatment might lead to higher willingness to participate in future rounds, which could further reduce the time until elimination. Involvement of local personnel and volunteers might add trust and participation.…”

Section: Discussionmentioning

confidence: 96%

Feasibility of Onchocerciasis Elimination Using a “Test-and-not-treat” Strategy in Loa loa Co-endemic Areas

Blok

Kamgno²,

Pion

et al. 2020

Clinical Infectious Diseases

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Background Mass drug administration (MDA) with ivermectin is the main strategy for onchocerciasis elimination. Ivermectin is generally safe but associated with serious adverse events in individuals with high Loa loa microfilarial densities (MFD). Therefore, ivermectin MDA is not recommended in areas where onchocerciasis is hypo-endemic and L. loa is co-endemic. To eliminate onchocerciasis in those areas, a test-and-not-treat (TaNT) strategy has been proposed. We investigated whether onchocerciasis elimination can be achieved using TaNT and the required duration. Methods We used the individual-based model ONCHOSIM to predict the impact of TaNT on onchocerciasis microfilarial (mf) prevalence. We simulated pre-control mf prevalence levels from 2-40%. The impact of TaNT was simulated under varying levels of participation, systematic non-participation and exclusion from ivermectin due to high L. loa MFD. For each scenario, we assessed the time to elimination, defined as bringing onchocerciasis mf prevalence below 1.4%. Results In areas with 30-40% pre-control mf prevalence, the model predicted that it would take between 14 and 16 years to bring the mf prevalence below 1.4% using conventional MDA, assuming 65% participation. TaNT would increase the time to elimination by up to 1.5 years, depending on the level of systematic non-participation and the exclusion rate. At lower exclusion rates (≤2.5%), the delay would be less than six months. Conclusions Our model predicts that onchocerciasis can be eliminated using TaNT in L. loa co-endemic areas. The required treatment duration using TaNT would be only slightly longer than in areas with conventional MDA, provided that participation is good.

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Section: Discussionmentioning

confidence: 96%

Feasibility of Onchocerciasis Elimination Using a “Test-and-not-treat” Strategy in Loa loa Co-endemic Areas

Blok

Kamgno²,

Pion

et al. 2020

Clinical Infectious Diseases

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“…Achieving EOT in Africa would lead to substantial health and economic benefits, reducing the needs for health workforce and outpatient services 61 . ATS needs and cost-effectiveness remain to be captured 37, 49, 62, 63 .…”

Section: Practical Implications Of the Currently Proposed Eot Goalsmentioning

confidence: 99%

“…Economic analyses of moxidectin, anti- Wolbachia therapies, macrofilaricides, and vector control (ground larviciding, slash-and-clear, adult fly traps) need to be conducted. The costs of test-and-not-treat for loiasis co-endemic areas were recently assessed in Cameroon 62 .…”

Section: Practical Implications Of the Currently Proposed Eot Goalsmentioning

confidence: 99%

The World Health Organization 2030 goals for onchocerciasis: Insights and perspectives from mathematical modelling

2019

Gates Open Res

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The World Health Organization (WHO) has embarked on a consultation process to refine the 2030 goals for priority neglected tropical diseases (NTDs), onchocerciasis among them. Current goals include elimination of transmission (EOT) by 2020 in Latin America, Yemen and selected African countries. The new goals propose that, by 2030, EOT be verified in 10 countries; mass drug administration (MDA) with ivermectin be stopped in at least one focus in 34 countries; and that the proportion of the population no longer in need of MDA be equal or greater than 25%, 50%, 75% and 100% in at least 16, 14, 12, and 10 countries, respectively. The NTD Modelling Consortium onchocerciasis teams have used EPIONCHO and ONCHOSIM to provide modelling insights into these goals. EOT appears feasible in low-moderate endemic areas with long-term MDA at high coverage (≥75%), but uncertain in areas of higher endemicity, poor coverage and adherence, and where MDA has not yet, or only recently, started. Countries will have different proportions of their endemic areas classified according to these categories, and this distribution of pre-intervention prevalence and MDA duration and programmatic success will determine the feasibility of achieving the proposed MDA cessation goals. Highly endemic areas would benefit from switching to biannual or quarterly MDA and implementing vector control where possible (determining optimal frequency and duration of anti-vectorial interventions requires more research). Areas without loiasis that have not yet initiated MDA should implement biannual (preferably with moxidectin) or quarterly MDA from the start. Areas with loiasis not previously treated would benefit from implementing test-and(not)-treat-based interventions, vector control, and anti- Wolbachia therapies, but their success will depend on the levels of screening and coverage achieved and sustained. The diagnostic performance of IgG4 Ov16 serology for assessing EOT is currently uncertain. Verification of EOT requires novel diagnostics at the individual- and population-levels.

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“…As only a small proportion of the population has to be excluded because of high L. loa mf density 34 , this strategy will likely be successful in almost the same timespan as with standard MDA if adherence is equally good. However, this strategy may be relatively costly 35 .…”

Section: Insights Gained From Modelling Analysesmentioning

confidence: 99%

The roadmap towards elimination of lymphatic filariasis by 2030: insights from quantitative and mathematical modelling

Group¹

2019

Gates Open Res

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The Global Programme to Eliminate Lymphatic Filariasis was launched in 2000 to eliminate lymphatic filariasis (LF) as a public health problem by 1) interrupting transmission through mass drug administration (MDA) and 2) offering basic care to those suffering from lymphoedema or hydrocele due to the infection. Although impressive progress has been made, the initial target year of 2020 will not be met everywhere. The World Health Organization recently proposed 2030 as the new target year for elimination of lymphatic filariasis (LF) as a public health problem. In this letter, LF modelers of the Neglected Tropical Diseases (NTDs) Modelling Consortium reflect on the proposed targets for 2030 from a quantitative perspective. While elimination as a public health problem seems technically and operationally feasible, it is uncertain whether this will eventually also lead to complete elimination of transmission. The risk of resurgence needs to be mitigated by strong surveillance after stopping interventions and sometimes perhaps additional interventions.

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A Test-and-Not-Treat Strategy for Onchocerciasis Elimination in Loa loa–coendemic Areas: Cost Analysis of a Pilot in the Soa Health District, Cameroon

Cited by 13 publications

References 15 publications

Feasibility of Onchocerciasis Elimination Using a “Test-and-not-treat” Strategy in Loa loa Co-endemic Areas

Feasibility of Onchocerciasis Elimination Using a “Test-and-not-treat” Strategy in Loa loa Co-endemic Areas

The World Health Organization 2030 goals for onchocerciasis: Insights and perspectives from mathematical modelling

The roadmap towards elimination of lymphatic filariasis by 2030: insights from quantitative and mathematical modelling

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