Analysis of interventions against the liver fluke, opisthorchis viverrini

Abstract

We adapt a population-based model of Opisthorchis viverrini transmission dynamics to determine the effectiveness of three different interventions. The model includes the definitive hosts, humans; the reservoir hosts, dogs and cats; and the intermediate hosts, snails and fish. We consider the interventions: education campaigns to reduce the consumption of raw or undercooked fish, improved sanitation and treatment through mass drug administration. We fit model parameters to a data set from two islands in southern Lao PDR. We calculate the control reproduction number, simulate different scenarios and optimise the interventions with optimal control. We look at the potential of the interventions to eliminate transmission within 20 years. The model shows that education and improved sanitation need a very high coverage to fulfil the goal of elimination, whereas annual drug distribution at medium coverage is sufficient. The best solution is a combination of drug distribution at a medium level of coverage and as high as possible coverage of education and improved sanitation.

Modeling the persistence of Opisthorchis viverrini worm burden after mass-drug administration and education campaigns with systematic adherence

“…The PBM we use for comparison with the ABM is an ordinary differential equation model that has been described and analysed in previously [ 31 , 32 ]. A schematic of the model is given in Fig 3 and Table 4 .…”

Modelling morbidity for neglected tropical diseases: the long and winding road from cumulative exposure to long-term pathology

“…Limited research has been performed on the population dynamics of liver fluke [ 47 ]. The first mathematical model for O. viverrini was published in 2018 [ 137 ], using a framework influenced by earlier macroparasite models, and this was subsequently extended to account for the impact of interventions with a focus on southern Lao PDR [ 138 ]. Similarly, a transmission model for C. sinensis in southern China was published in 2018 [ 139 ]; however, this compartmental model does not consider the worm burden, rather that hosts are either susceptible or infected, and inferred a large number of initial states and parameters from sparse data, leading to biologically implausible output (for instance, the initial population size of snails is 1026, whereas that of fish is 10.2 million).…”

Assessment of control strategies against Clonorchis sinensis infection based on a multi-group dynamic transmission model

“…The approach for calculation of control reproduction number (R c ) in the system with interventions is similar as that of R 0 . With the assumption that chemotherapy is distributed PLOS NEGLECTED TROPICAL DISEASES continuously [24], R c is expressed as following:…”

“…And control strategies focus on population with raw fish consumption instead of whole population cannot be assessed under these models. Interestingly, Bürli and colleges [24,25] developed deterministic models of Opisthorchis viverrini transmission dynamics to evaluate the long-term effectiveness of different interventions (e.g., MDA, IEC, and environmental modification), by including the parameters of interventions inside the models and simulating different scenarios. O. viverrini, known as the other major species of liver fluke, have very similar life cycle as C. sinensis [26].…”

“…In this paper, with extension of Dai's transmission model and reference of Bürli's intervention model [20,24], we developed a multi-group deterministic SIS transmission model to: (1) describing the transmission dynamics among groups of population with different raw-fishconsumption behaviors and (2) quantitatively assessing the long-term effectiveness of different intervention strategies on control of C. sinensis infection through simulating scenarios. As a practical example, the model was applied in Fusha Town, a typical clonorchiasis endemic area with raw-fish-eating culture in Guangdong province, China.…”