Introduction
helminth infection, infection, infections, human mobility
INFECTIOUS DISEASES, DISEASES, DISEASE, HOOKWORM, INFECTIONS, INFECTION, WORM INFECTION, HELMINTH INFECTION, DISEASES
One contribution of 14 to a theme issue ‘Human mobility contributes to the spatial dynamics of many infectious diseases, and understanding these dynamics helps us to determine the most effective ways to intervene and plan surveillance. In this paper, we describe a novel transmission model for the spatial dynamics of hookworm, a parasitic worm which is a common infection across sub-Saharan Africa, East Asia and the Pacific islands. We fit our model, with and without mobility, to data obtained from a sub-county in Kenya, and validate the model's predictions against the decline in prevalence observed over the course of a clustered randomized control trial evaluating methods of administering mass chemotherapy. We find that our model which incorporates human mobility is able to reproduce the observed patterns in decline of prevalence during the TUMIKIA trial, and additionally, that the widespread bounce-back of infection may be possible over many years, depending on the rates of people movement between villages. The results have important implications for the design of mass chemotherapy programmes for the elimination of human helminth transmission.This article is part of the theme issue ‘Challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs’.The measurement and prediction of the spatial distribution and spread of infection within and between defined population units, e.g. towns, cities and villages, are vital considerations for planning epidemiological interventions [Diseases caused by helminth worm infections, affect over two billion people worldwide and are endemic in many of the world's low- and middle-income countries [Space is an important factor to take into consideration for understanding patterns of both directly and indirectly spread infectious agents that are endemic in large populations, because while normally the majority of transmission is local, movement of humans (or disease vectors) may affect transmission elsewhere. This is especially the case when prevalence is focal, as it is often uncertain when ongoing transmission is sustained purely locally or only because of influence from further away by the repeated input of new infections from other spatial locations. In such situations, it is useful to know how efforts to control the disease in one location affects the dynamics of infection in other surrounding areas or if infection is likely to return after control has ended with the elimination of transmission in a defined area. Many studies, reveal much heterogeneity in the spatial pattern of helminth infection prevalence across multi-village communities [When human movement is completely random, diffusion models can be used to model spatial spread [