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A Framework for Decision-Making for Mass Distribution of Mectizan(R) in Areas Endemic for Loa loa.

Addiss DG, Rheingans R, Twum-Danso NA, Richards FO - Filaria J (2003)

Bottom Line: RESULTS: In the model, all four strategies significantly reduced risk of death and neurologic complications from L. loa encephalopathy, but RAPLOA-20 and REA resulted in half as many such cases as did RAPLOA-40 or combined REA/RAPLOA-40.It also may be cost-saving.Before full-scale implementation, additional data are needed on geographic clustering of high-density L. loa microfilaremia and on RAPLOA's reliability and cost.

View Article: PubMed Central - HTML - PubMed

Affiliation: U,S, Centers for Disease Control and Prevention, Atlanta, GA, USA. dga1@cdc.gov

ABSTRACT
BACKGROUND: The occurrence of Loa loa encephalopathy following mass treatment of onchocerciasis with Mectizan(R) has adversely affected onchocerciasis control efforts in central Africa. Persons with very high densities of L. loa microfilaremia are at increased risk of encephalopathy, but little is known about the geographic distribution of these persons within central Africa. RAPLOA, a new technique that correlates the proportion of community members reporting a history of eyeworm with the prevalence of high-intensity L. loa microfilaremia in that community, may be useful for rapid assessment of areas at potential risk of treatment-related L. loa encephalopathy. Validation of RAPLOA is ongoing. The operational and risk-reduction advantages of RAPLOA over the current technique of village-by-village rapid epidemiologic assessment for onchocerciasis (REA) are unknown. METHODS: We developed a decision model to compare four strategies for minimizing sequelae of L. loa encephalopathy following mass treatment with Mectizan(R) in areas co-endemic for onchocerciasis and loiasis: REA; RAPLOA with threshold eyeworm prevalences of 40% and 20% (RAPLOA-40 and RAPLOA-20, respectively); and combined REA/RAPLOA-40. RESULTS: In the model, all four strategies significantly reduced risk of death and neurologic complications from L. loa encephalopathy, but RAPLOA-20 and REA resulted in half as many such cases as did RAPLOA-40 or combined REA/RAPLOA-40. CONCLUSION: RAPLOA is likely to be useful programmatically in reducing risk of L. loa encephalopathy following mass treatment with Mectizan(R). It also may be cost-saving. Before full-scale implementation, additional data are needed on geographic clustering of high-density L. loa microfilaremia and on RAPLOA's reliability and cost.

No MeSH data available.


Related in: MedlinePlus

Decision model of four strategies to reduce risk of L. loa encephalopathy following treatment with Mectizan® in areas that are 1) thought to be endemic for loiasis on the basis of remote sensing (the environmental risk model map); and 2) determined to be hyper- or meso-endemic for onchocerciasis by REMO. Abbreviations: oncho = onchocerciasis; Rx = treatment. Additional details on the model are available from the authors upon request. [+] indicates truncation of a branch to simplify the figure. For the remainder of this branch, see the structure of similarly labelled branches elsewhere in the figure.
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Figure 3: Decision model of four strategies to reduce risk of L. loa encephalopathy following treatment with Mectizan® in areas that are 1) thought to be endemic for loiasis on the basis of remote sensing (the environmental risk model map); and 2) determined to be hyper- or meso-endemic for onchocerciasis by REMO. Abbreviations: oncho = onchocerciasis; Rx = treatment. Additional details on the model are available from the authors upon request. [+] indicates truncation of a branch to simplify the figure. For the remainder of this branch, see the structure of similarly labelled branches elsewhere in the figure.

Mentions: The model was constructed in the standard fashion using TreeAge software (Williamstown, MA). Four strategies (REA, RAPLOA-40, RAPLOA-20, and combined REA/RAPLOA-40) were examined (Figure 3) under four different ecologic conditions with varying intensities of O. volvulus and L. loa transmission (Appendix - see additional file 1). We examined three principal outcomes: 1) onchocercal blindness; 2) chronic neurologic complications or death associated with L. loa encephalopathy following Mectizan® treatment; and 3) disability-adjusted life years (DALYs), which were influenced by onchocercal blindness and skin disease as well as by treatment-related L. loa encephalopathy, death, and chronic neurologic sequelae (Appendix - see additional file 1) [12]. DALY losses for onchocercal blindness and skin disease were extrapolated from the Global Burden of Disease estimates (Appendix - see additional file 1) [12]. No similar estimates are available for Loa loa-related events. As a result, authors' estimates were used to reflect a short-term serious event (L. loa encephalopathy), a chronic severe event (permanent neurologic sequelae), and death at unknown age. Economic outcomes, particularly the costs associated with the various approaches, were not included because data were not available.


A Framework for Decision-Making for Mass Distribution of Mectizan(R) in Areas Endemic for Loa loa.

Addiss DG, Rheingans R, Twum-Danso NA, Richards FO - Filaria J (2003)

Decision model of four strategies to reduce risk of L. loa encephalopathy following treatment with Mectizan® in areas that are 1) thought to be endemic for loiasis on the basis of remote sensing (the environmental risk model map); and 2) determined to be hyper- or meso-endemic for onchocerciasis by REMO. Abbreviations: oncho = onchocerciasis; Rx = treatment. Additional details on the model are available from the authors upon request. [+] indicates truncation of a branch to simplify the figure. For the remainder of this branch, see the structure of similarly labelled branches elsewhere in the figure.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2147661&req=5

Figure 3: Decision model of four strategies to reduce risk of L. loa encephalopathy following treatment with Mectizan® in areas that are 1) thought to be endemic for loiasis on the basis of remote sensing (the environmental risk model map); and 2) determined to be hyper- or meso-endemic for onchocerciasis by REMO. Abbreviations: oncho = onchocerciasis; Rx = treatment. Additional details on the model are available from the authors upon request. [+] indicates truncation of a branch to simplify the figure. For the remainder of this branch, see the structure of similarly labelled branches elsewhere in the figure.
Mentions: The model was constructed in the standard fashion using TreeAge software (Williamstown, MA). Four strategies (REA, RAPLOA-40, RAPLOA-20, and combined REA/RAPLOA-40) were examined (Figure 3) under four different ecologic conditions with varying intensities of O. volvulus and L. loa transmission (Appendix - see additional file 1). We examined three principal outcomes: 1) onchocercal blindness; 2) chronic neurologic complications or death associated with L. loa encephalopathy following Mectizan® treatment; and 3) disability-adjusted life years (DALYs), which were influenced by onchocercal blindness and skin disease as well as by treatment-related L. loa encephalopathy, death, and chronic neurologic sequelae (Appendix - see additional file 1) [12]. DALY losses for onchocercal blindness and skin disease were extrapolated from the Global Burden of Disease estimates (Appendix - see additional file 1) [12]. No similar estimates are available for Loa loa-related events. As a result, authors' estimates were used to reflect a short-term serious event (L. loa encephalopathy), a chronic severe event (permanent neurologic sequelae), and death at unknown age. Economic outcomes, particularly the costs associated with the various approaches, were not included because data were not available.

Bottom Line: RESULTS: In the model, all four strategies significantly reduced risk of death and neurologic complications from L. loa encephalopathy, but RAPLOA-20 and REA resulted in half as many such cases as did RAPLOA-40 or combined REA/RAPLOA-40.It also may be cost-saving.Before full-scale implementation, additional data are needed on geographic clustering of high-density L. loa microfilaremia and on RAPLOA's reliability and cost.

View Article: PubMed Central - HTML - PubMed

Affiliation: U,S, Centers for Disease Control and Prevention, Atlanta, GA, USA. dga1@cdc.gov

ABSTRACT
BACKGROUND: The occurrence of Loa loa encephalopathy following mass treatment of onchocerciasis with Mectizan(R) has adversely affected onchocerciasis control efforts in central Africa. Persons with very high densities of L. loa microfilaremia are at increased risk of encephalopathy, but little is known about the geographic distribution of these persons within central Africa. RAPLOA, a new technique that correlates the proportion of community members reporting a history of eyeworm with the prevalence of high-intensity L. loa microfilaremia in that community, may be useful for rapid assessment of areas at potential risk of treatment-related L. loa encephalopathy. Validation of RAPLOA is ongoing. The operational and risk-reduction advantages of RAPLOA over the current technique of village-by-village rapid epidemiologic assessment for onchocerciasis (REA) are unknown. METHODS: We developed a decision model to compare four strategies for minimizing sequelae of L. loa encephalopathy following mass treatment with Mectizan(R) in areas co-endemic for onchocerciasis and loiasis: REA; RAPLOA with threshold eyeworm prevalences of 40% and 20% (RAPLOA-40 and RAPLOA-20, respectively); and combined REA/RAPLOA-40. RESULTS: In the model, all four strategies significantly reduced risk of death and neurologic complications from L. loa encephalopathy, but RAPLOA-20 and REA resulted in half as many such cases as did RAPLOA-40 or combined REA/RAPLOA-40. CONCLUSION: RAPLOA is likely to be useful programmatically in reducing risk of L. loa encephalopathy following mass treatment with Mectizan(R). It also may be cost-saving. Before full-scale implementation, additional data are needed on geographic clustering of high-density L. loa microfilaremia and on RAPLOA's reliability and cost.

No MeSH data available.


Related in: MedlinePlus