Simulation modelling of population dynamics of mosquito vectors for rift valley Fever virus in a disease epidemic setting.

Clement N Mweya,Niels Holst,Sharadhuli I Kimera,Leonard E G Mboera,Jens H Kuhn

doi:10.1371/journal.pone.0108430

Clement N Mweya, Niels Holst + Show 3 more

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https://doi.org/10.1371/journal.pone.0108430

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Abstract

BackgroundRift Valley Fever (RVF) is weather dependent arboviral infection of livestock and humans. Population dynamics of mosquito vectors is associated with disease epidemics. In our study, we use daily temperature and rainfall as model inputs to simulate dynamics of mosquito vectors population in relation to disease epidemics.Methods/FindingsTime-varying distributed delays (TVDD) and multi-way functional response equations were implemented to simulate mosquito vectors and hosts developmental stages and to establish interactions between stages and phases of mosquito vectors in relation to vertebrate hosts for infection introduction in compartmental phases. An open-source modelling platforms, Universal Simulator and Qt integrated development environment were used to develop models in C++ programming language. Developed models include source codes for mosquito fecundity, host fecundity, water level, mosquito infection, host infection, interactions, and egg time. Extensible Markup Language (XML) files were used as recipes to integrate source codes in Qt creator with Universal Simulator plug-in. We observed that Floodwater Aedines and Culicine population continued to fluctuate with temperature and water level over simulation period while controlled by availability of host for blood feeding. Infection in the system was introduced by floodwater Aedines. Culicines pick infection from infected host once to amplify disease epidemic. Simulated mosquito population show sudden unusual increase between December 1997 and January 1998 a similar period when RVF outbreak occurred in Ngorongoro district.Conclusion/SignificanceFindings presented here provide new opportunities for weather-driven RVF epidemic simulation modelling. This is an ideal approach for understanding disease transmission dynamics towards epidemics prediction, prevention and control. This approach can be used as an alternative source for generation of calibrated RVF epidemics data in different settings.

Highlights

Rift Valley fever (RVF) is an infection caused by arbovirus belonging to genus Phlebovirus of the family Bunyaviridae
Mosquito population dynamics simulated for both floodwater Aedines and Culicine showed relationship with daily temperatures and rainfall fluctuate over a period from 1994 to January 1999 (Figure 2A) and rainfall data used to determine estimated amount of water in breeding sites for Aedine mosquitoes (Figure 2B)
Water level threshold for emergence of infectious floodwater is adjusted to reflect the biological role of floodwater Aedine in Rift Valley Fever (RVF) epidemics

Summary

Introduction

Rift Valley fever (RVF) is an infection caused by arbovirus belonging to genus Phlebovirus of the family Bunyaviridae. Many of them are based on previously developed epidemiological model of RVF that focus mainly on animals and vectors population dynamics with hypothetical consideration of infection dynamics [32]. Further development of this model incorporated the role of vaccination and vector control to describe epidemiology of RVFV in areas of intense transmission [34,35]. The role of daily weather data such as temperature and rainfall as model input to determine vector populations have not previously been directly considered This limits their further applicability in predictive epidemiology due to insufficient incorporation of weather data and on-the-ground biological processes related to RVF disease. 206 Celsius degrees 74 Celsius degrees 6 to 11 years 365 days 152 days 200 sheep per square kilometre

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