The types of diseases examined are zoonotic ones (diseases that can spread from one species to another, specifically from animals to people, which represents the majority of emerging disease, with Ebola and Zika being prominent cases-in-point.) The idea is construct a predictive model to allow countries and their health agencies to better prepare for and respond to disease outbreaks.
While Ebola and Zika are current diseases of concern, the explanatory power of the model extends to other diseases, including Rift Valley fever and Lassa fever. Each of these diseases has an association with particular environmental conditions. The main example of the model is with Lassa fever.
Lassa fever can cause haemorrhagic fever (like Ebola); it is passed onto people from rats and it affects large parts of West Africa. The disease is caused by the Lassa virus and it was first described in 1969 in the town of Lassa, in Borno State, Nigeria. Predictions for the disease show that it will double, in terms of the numbers of people infected, by 2070. A recent tweet from Microbes&Infection (@MicrobesInfect), drawing on World Health Organization data, indicated “#Lassa Fever claims 149 lives in Nigeria in the last 9 months.”
The model considers changes in the host’s distribution (in the case of Lassa fever — rats) as the environment changes. This allows scientists to calculate how often a person is likely to come into contact with an infected animal. To build the model, locations of known Lassa fever outbreak for the period 1967 – 2012 were studied (some 408 locales). These data were off-set with patterns of land use, crop yields, temperature patterns and rainfall figures.
The model received interest within the science community, with one researcher Ogo Maduewesi (@OgoMaduewesi) tweeting: “Lassa fever is a product of unkempt environment.”
Expanding further on the model, Professor Kate Jones from University College London, stated: “Our model can help decision-makers assess the likely impact of any interventions or change in national or international government policies, such as the conversion of grasslands to agricultural lands, on zoonotic transmission.”
The model is also, Professor Jones explained, flexible enough to cope with factors like climate change and population increase. The research group believe their model to robust and in having a strong predictive power.
The model is outlined in the journal Methods in Ecology and Evolution. The research is titled “Environmental-mechanistic modelling of the impact of global change on human zoonotic disease emergence: a case study of Lassa fever.”
