Required Duration of Mass Ivermectin Treatment for Onchocerciasis Elimination in Africa: a Comparative Modelling Analysis

Overview

Journal Parasit Vectors

Publisher Biomed Central

Specialties Parasitology
Tropical Medicine

Date 2015 Oct 23

PMID 26489937

Citations 78

Authors

Wilma A Stolk

Martin Walker

Luc E Coffeng

Maria-Gloria Basanez

Sake J de Vlas

Affiliations

Soon will be listed here.

Abstract

Background: The World Health Organization (WHO) has set ambitious targets for the elimination of onchocerciasis by 2020-2025 through mass ivermectin treatment. Two different mathematical models have assessed the feasibility of reaching this goal for different settings and treatment scenarios, namely the individual-based microsimulation model ONCHOSIM and the population-based deterministic model EPIONCHO. In this study, we harmonize some crucial assumptions and compare model predictions on common outputs.

Methods: Using a range of initial endemicity levels and treatment scenarios, we compared the models with respect to the following outcomes: 1) model-predicted trends in microfilarial (mf) prevalence and mean mf intensity during 25 years of (annual or biannual) mass ivermectin treatment; 2) treatment duration needed to bring mf prevalence below a provisional operational threshold for treatment interruption (pOTTIS, i.e. 1.4 %), and 3) treatment duration needed to drive the parasite population to local elimination, even in the absence of further interventions. Local elimination was judged by stochastic fade-out in ONCHOSIM and by reaching transmission breakpoints in EPIONCHO.

Results: ONCHOSIM and EPIONCHO both predicted that in mesoendemic areas the pOTTIS can be reached with annual treatment, but that this strategy may be insufficient in very highly hyperendemic areas or would require prolonged continuation of treatment. For the lower endemicity levels explored, ONCHOSIM predicted that the time needed to reach the pOTTIS is longer than that needed to drive the parasite population to elimination, whereas for the higher endemicity levels the opposite was true. In EPIONCHO, the pOTTIS was reached consistently sooner than the breakpoint.

Conclusions: The operational thresholds proposed by APOC may have to be adjusted to adequately reflect differences in pre-control endemicities. Further comparative modelling work will be conducted to better understand the main causes of differences in model-predicted trends. This is a pre-requisite for guiding elimination programmes in Africa and refining operational criteria for stopping mass treatment.

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References

Plaisier A, Van Oortmarssen G, Remme J, Alley E, Habbema J . The risk and dynamics of onchocerciasis recrudescence after cessation of vector control. Bull World Health Organ. 1991; 69(2):169-78. PMC: 2393088. View

Coffeng L, Bakker R, Montresor A, de Vlas S . Feasibility of controlling hookworm infection through preventive chemotherapy: a simulation study using the individual-based WORMSIM modelling framework. Parasit Vectors. 2015; 8:541. PMC: 4618856. DOI: 10.1186/s13071-015-1151-4. View

Rodriguez-Perez M, Lutzow-Steiner M, Segura-Cabrera A, Lizarazo-Ortega C, Dominguez-Vazquez A, Sauerbrey M . Rapid suppression of Onchocerca volvulus transmission in two communities of the Southern Chiapas focus, Mexico, achieved by quarterly treatments with Mectizan. Am J Trop Med Hyg. 2008; 79(2):239-44. PMC: 2570542. View

Boyd A, Won K, McClintock S, Donovan C, Laney S, Williams S . A community-based study of factors associated with continuing transmission of lymphatic filariasis in Leogane, Haiti. PLoS Negl Trop Dis. 2010; 4(3):e640. PMC: 2843627. DOI: 10.1371/journal.pntd.0000640. View

Turner H, Walker M, Churcher T, Basanez M . Modelling the impact of ivermectin on River Blindness and its burden of morbidity and mortality in African Savannah: EpiOncho projections. Parasit Vectors. 2014; 7:241. PMC: 4037555. DOI: 10.1186/1756-3305-7-241. View

Brieger W, Okeibunor J, Abiose A, Ndyomugyenyi R, Wanji S, Elhassan E . Characteristics of persons who complied with and failed to comply with annual ivermectin treatment. Trop Med Int Health. 2012; 17(7):920-30. DOI: 10.1111/j.1365-3156.2012.03007.x. View

Coffeng L, Stolk W, Zoure H, Veerman J, Agblewonu K, Murdoch M . African Programme For Onchocerciasis Control 1995-2015: model-estimated health impact and cost. PLoS Negl Trop Dis. 2013; 7(1):e2032. PMC: 3561133. DOI: 10.1371/journal.pntd.0002032. View

Plaisier A, Subramanian S, Das P, Souza W, Lapa T, Furtado A . The LYMFASIM simulation program for modeling lymphatic filariasis and its control. Methods Inf Med. 1998; 37(1):97-108. View

Duerr H, Dietz K, Eichner M . Determinants of the eradicability of filarial infections: a conceptual approach. Trends Parasitol. 2005; 21(2):88-96. DOI: 10.1016/j.pt.2004.11.011. View

10.

Rodriguez-Perez M, Fernandez-Santos N, Orozco-Algarra M, Rodriguez-Atanacio J, Dominguez-Vazquez A, Rodriguez-Morales K . Elimination of Onchocerciasis from Mexico. PLoS Negl Trop Dis. 2015; 9(7):e0003922. PMC: 4498594. DOI: 10.1371/journal.pntd.0003922. View

11.

Anderson J, Fuglsang H, Hamilton P, de Marshall T . Studies on onchocerciasis in the United Cameroon Republic. II. Comparison of onchocerciasis in rain-forest and Sudan-savanna. Trans R Soc Trop Med Hyg. 1974; 68(3):209-22. DOI: 10.1016/0035-9203(74)90117-5. View

12.

Duerr H, Raddatz G, Eichner M . Control of onchocerciasis in Africa: threshold shifts, breakpoints and rules for elimination. Int J Parasitol. 2011; 41(5):581-9. DOI: 10.1016/j.ijpara.2010.12.009. View

13.

Kim Y, Remme J, Steinmann P, Stolk W, Roungou J, Tediosi F . Control, elimination, and eradication of river blindness: scenarios, timelines, and ivermectin treatment needs in Africa. PLoS Negl Trop Dis. 2015; 9(4):e0003664. PMC: 4393239. DOI: 10.1371/journal.pntd.0003664. View

14.

Plaisier A, Alley E, Van Oortmarssen G, Boatin B, Habbema J . Required duration of combined annual ivermectin treatment and vector control in the Onchocerciasis Control Programme in west Africa. Bull World Health Organ. 1997; 75(3):237-45. PMC: 2486951. View

15.

Schulz-Key H, Karam M . Periodic reproduction of Onchocerca volvulus. Parasitol Today. 1986; 2(10):284-6. DOI: 10.1016/0169-4758(86)90138-9. View

16.

Alley E, Plaisier A, Boatin B, Dadzie K, Remme J, Zerbo G . The impact of five years of annual ivermectin treatment on skin microfilarial loads in the onchocerciasis focus of Asubende, Ghana. Trans R Soc Trop Med Hyg. 1994; 88(5):581-4. DOI: 10.1016/0035-9203(94)90172-4. View

17.

Turner H, Churcher T, Walker M, Osei-Atweneboana M, Prichard R, Basanez M . Uncertainty surrounding projections of the long-term impact of ivermectin treatment on human onchocerciasis. PLoS Negl Trop Dis. 2013; 7(4):e2169. PMC: 3636241. DOI: 10.1371/journal.pntd.0002169. View

18.

Katabarwa M, Eyamba A, Nwane P, Enyong P, Yaya S, Baldiagai J . Seventeen years of annual distribution of ivermectin has not interrupted onchocerciasis transmission in North Region, Cameroon. Am J Trop Med Hyg. 2011; 85(6):1041-9. PMC: 3225149. DOI: 10.4269/ajtmh.2011.11-0333. View

19.

Traore M, Sarr M, Badji A, Bissan Y, Diawara L, Doumbia K . Proof-of-principle of onchocerciasis elimination with ivermectin treatment in endemic foci in Africa: final results of a study in Mali and Senegal. PLoS Negl Trop Dis. 2012; 6(9):e1825. PMC: 3441490. DOI: 10.1371/journal.pntd.0001825. View

20.

Basanez M, Boussinesq M . Population biology of human onchocerciasis. Philos Trans R Soc Lond B Biol Sci. 1999; 354(1384):809-26. PMC: 1692549. DOI: 10.1098/rstb.1999.0433. View