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Modelling the spread of emerging epidemics; the case of Citrus Greening

Citrus Greening

Researchers develop a model allowing characterisation of the disease transmission process

Scientists at Rothamsted Research, working alongside Cambridge University have developed a model allowing characterisation of the disease transmission process, even when epidemiological data are limited due to the presence of control measures.

Plant disease epidemics are a considerable problem both in natural environments and in commercial agriculture. When there is an emerging epidemic, control measures are imposed to prevent further spread. This fact results in complications in fully characterizing the disease and limits the availability of data that could allow an assessment of the effectiveness of the control measures imposed.

Using citrus greening as a case study, Rothamsted researchers in a study led by colleagues at the University of Cambridge, developed a method that is able to characterize the disease transmission process and the temporal and spatial patterns of the pathogen’s invasion when the epidemiological parameters had to be estimated. The study is published in the journal Proceedings of the National Academy of Sciences (PNAS).

Huanglongbing (HLB) also known as Citrus Greening is one of the world’s most destructive plant diseases and has inflicted severe economic losses in citrus-growing regions in the past decade.  No known commercial viable cure is currently available and the US government have allocated $125M of research funding for the disease.  The team of researchers used data from more than 250,000 trees in the Southern Gardens plantation in south Florida to model the spread of the epidemic and were able to extract epidemiological parameters even though control measures had been imposed.

Dr Stephen Parnell of Rothamsted Research, which is strategically funded by the BBSRC, said: “HLB is an extremely damaging disease and continues to spread throughout the citrus regions of the world.  This study not only provides insights into the epidemiology of HLB but it could also help estimate the costs and benefits of surveillance and control strategies."

Dr Matthew Parry of University of Otago New Zealand added "our model was able to incorporate information about the spraying programme that was used against the insects spreading HLB. This meant we could quantify the key characteristics of the underlying epidemic, even with control strategies in place."

Professor Christopher Gilligan of Cambridge University who receives support a BBSRC Professorial Fellowship and led the study, said “the remarkable data set collected by colleagues for citrus greening in Florida has enabled us to test a new epidemiological and statistical methodology that can be used to predict the spread of a wide range of emerging epidemics.”



Notes to Editors

About University of Cambridge

The mission of the University of Cambridge is to contribute to society through the pursuit of education, learning and research at the highest international levels of excellence. To date, 90 affiliates of the University have won the Nobel Prize.

Founded in 1209, the University comprises 31 autonomous Colleges, which admit undergraduates and provide small-group tuition, and 150 departments, faculties and institutions.

Cambridge is a global university. Its 19,000 student body includes 3,700 international students from 120 countries. Cambridge researchers collaborate with colleagues worldwide, and the University has established larger-scale partnerships in Asia, Africa and America.

The University sits at the heart of one of the world's largest technology clusters. The 'Cambridge Phenomenon' has created 1,500 hi-tech companies, 12 of them valued at over US$1 billion and two at over US$10 billion. Cambridge promotes the interface between academia and business, and has a global reputation for innovation.

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About Rothamsted Research

We are the longest running agricultural research station in the world, providing cutting-edge science and innovation for over 170 years. Our mission is to deliver the knowledge and new practices to increase crop productivity and quality and to develop environmentally sustainable solutions for food and energy production.

Our strength lies in the integrated, multidisciplinary approach to research in plant, insect and soil science.

Rothamsted Research is strategically funded by the Biotechnology and Biological Sciences Research Council (BBSRC). In 2013-2014 Rothamsted Researched received a total of £32.9M from the BBSRC.


The Biotechnology and Biological Sciences Research Council (BBSRC) invests in world-class bioscience research and training on behalf of the UK public. Our aim is to further scientific knowledge, to promote economic growth, wealth and job creation and to improve quality of life in the UK and beyond.

Funded by Government, BBSRC invested over £509M in world-class bioscience in 2014-15. We support research and training in universities and strategically funded institutes. BBSRC research and the people we fund are helping society to meet major challenges, including food security, green energy and healthier, longer lives. Our investments underpin important UK economic sectors, such as farming, food, industrial biotechnology and pharmaceuticals.

For more information about BBSRC, our science and our impact see:

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