Epidemiological Modelling for Monitoring and Evaluation of Lymphatic Filariasis Control

Michael, Edwin; Malecela‐Lazaro, Mwele N.; Kazura, James W.

doi:10.1016/s0065-308x(07)65003-9

Cited by 42 publications

(40 citation statements)

References 73 publications

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“…Local dynamics imply different targets for parasite elimination and anticipatory approaches to the management of elimination, based on globally-set thresholds, are unlikely to achieve global filariasis elimination [9,29,30,33]. Urgent work is now required to characterize the nature of variability in local parasite transmission and extinction dynamics using adaptive model-fitting methods, and to test and validate alternative management tactics if we are to develop and successfully deploy a more informed theory of parasite elimination.…”

Section: Discussionmentioning

confidence: 99%

Geographic and ecologic heterogeneity in elimination thresholds for the major vector-borne helminthic disease, lymphatic filariasis

et al. 2010

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BackgroundLarge-scale intervention programmes to control or eliminate several infectious diseases are currently underway worldwide. However, a major unresolved question remains: what are reasonable stopping points for these programmes? Recent theoretical work has highlighted how the ecological complexity and heterogeneity inherent in the transmission dynamics of macroparasites can result in elimination thresholds that vary between local communities. Here, we examine the empirical evidence for this hypothesis and its implications for the global elimination of the major macroparasitic disease, lymphatic filariasis, by applying a novel Bayesian computer simulation procedure to fit a dynamic model of the transmission of this parasitic disease to field data from nine villages with different ecological and geographical characteristics. Baseline lymphatic filariasis microfilarial age-prevalence data from three geographically distinct endemic regions, across which the major vector populations implicated in parasite transmission also differed, were used to fit and calibrate the relevant vector-specific filariasis transmission models. Ensembles of parasite elimination thresholds, generated using the Bayesian fitting procedure, were then examined in order to evaluate site-specific heterogeneity in the values of these thresholds and investigate the ecological factors that may underlie such variabilityResultsWe show that parameters of density-dependent functions relating to immunity, parasite establishment, as well as parasite aggregation, varied significantly between the nine different settings, contributing to locally varying filarial elimination thresholds. Parasite elimination thresholds predicted for the settings in which the mosquito vector is anopheline were, however, found to be higher than those in which the mosquito is culicine, substantiating our previous theoretical findings. The results also indicate that the probability that the parasite will be eliminated following six rounds of Mass Drug Administration with diethylcarbamazine and albendazole decreases markedly but non-linearly as the annual biting rate and parasite reproduction number increases.ConclusionsThis paper shows that specific ecological conditions in a community can lead to significant local differences in population dynamics and, consequently, elimination threshold estimates for lymphatic filariasis. These findings, and the difficulty of measuring the key local parameters (infection aggregation and acquired immunity) governing differences in transmission thresholds between communities, mean that it is necessary for us to rethink the utility of the current anticipatory approaches for achieving the elimination of filariasis both locally and globally.

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Section: Discussionmentioning

confidence: 99%

Geographic and ecologic heterogeneity in elimination thresholds for the major vector-borne helminthic disease, lymphatic filariasis

et al. 2010

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“…Model-predicted trends in infection indicators during MDA can be used as a reference curve, against which achievements of actual programmes can be compared to assess whether they are performing well. This was discussed and illustrated by Michael et al (2006bMichael et al ( , 2007. Such a comparison might reveal that observed declines in infection indicators are smaller than predicted by models.…”

Section: Modelling Lymphatic Filariasis Transmission and Controlmentioning

confidence: 96%

“…Unfortunately, knowledge on the operation of density-dependent mechanisms regulating the parasite density in human hosts is incomplete, due to the difficulties in measuring the adult worm burden. Michael et al (2007Michael et al ( , 2006a analyzed data from the literature on the association between annual biting rate and overall mf prevalence using a general model; they estimated the threshold biting rate at 833 bites per person per year (p.p.p.y) for areas where Culex and Aedes mosquito species are responsible for transmission and at 2,375 bites p.p.p.y where Anopheles spp. act as main vectors.…”

Section: Vector Controlmentioning

confidence: 99%

Modelling Lymphatic Filariasis Transmission and Control: Modelling Frameworks, Lessons Learned and Future Directions

Stolk¹,

Stone²,

Vlas³

2015

Advances in Parasitology

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“…In this background, Micheal et al [63, 64] suggest that plans to control lymphatic filariasis should be more pragmatic, flexible, economically sensitive, and sequential. They suggest that the first target in an elimination programme should be to achieve an infection rate at which chronic manifestations of infection (causing more productivity loss and DALYs) become negligible despite ongoing infection.…”

Section: Resurgence After Mda: Is Eradication Possible?mentioning

confidence: 99%

Current Evidence on the Use of Antifilarial Agents in the Management of bancroftian Filariasis

Fernando

Rodrigo

Rajapakse

2011

Journal of Tropical Medicine

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Many trials have explored the efficacy of individual drugs and drug combinations to treat bancroftian filariasis. This narrative review summarizes the current evidence for drug management of bancroftian filariasis. Diethylcarbamazine (DEC) remains the prime antifilarial agent with a well-established microfilaricidal and some macrofilaricidal effects. Ivermectin (IVM) is highly microfilaricidal but minimally macrofilaricidal. The role of albendazole (ALB) in treatment regimens is not well established though the drug has a microfilaricidal effect. The combination of DEC+ALB has a better long-term impact than IVM+ALB. Recent trials have shown that doxycycline therapy against Wolbachia, an endosymbiotic bacterium of the parasite, is capable of reducing microfilaria rates and adult worm activity. Followup studies on mass drug administration (MDA) are yet to show a complete interruption of transmission, though the infection rates are reduced to a very low level.

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Epidemiological Modelling for Monitoring and Evaluation of Lymphatic Filariasis Control

Cited by 42 publications

References 73 publications

Geographic and ecologic heterogeneity in elimination thresholds for the major vector-borne helminthic disease, lymphatic filariasis

Geographic and ecologic heterogeneity in elimination thresholds for the major vector-borne helminthic disease, lymphatic filariasis

Modelling Lymphatic Filariasis Transmission and Control: Modelling Frameworks, Lessons Learned and Future Directions

Current Evidence on the Use of Antifilarial Agents in the Management of bancroftian Filariasis

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