Researchers at Princeton University and Harvard University have used anonymous mobile phone records for more than 15 million people to track the spread of rubella disease in Kenya and were able to quantitatively show that mobile phone data can predict seasonal disease patterns.
Harnessing mobile phone data in this way could help policymakers guide and evaluate health interventions like the timing of vaccinations and school closings. The researchers’ methodology also could apply to a number of seasonally transmitted diseases such as the flu and measles.
“One of the unique opportunities of mobile phone data is the ability to understand how travel patterns change over time. And rubella is a well-known seasonal disease that has been hypothesized to be driven by human population dynamics, making it a good system for us to test.”
In the past, it was difficult to collect data on individuals in low-income and undeveloped countries due to a lack of technology usage. But mobile phone ownership, especially in these areas, is rapidly increasing, producing large and complex datasets on millions of people. Because of the mobility of cellphones, it is possible that phone records could predict certain health-related patterns. This spurred the researchers to take a closer look.
Ultimately, the research team wanted to see whether cellphone users and their movement around the country could predict the seasonal spread of rubella. The researchers used available records to analyze mobile phone usage and movement between June 2008 and June 2009 for more than 15 million cellphone users in Kenya. (Note: February 2009 was missing from the dataset.)
Using the location of the routing tower and the timing of each call and text message, the researchers were able to determine a daily location for each user as well as the number of trips these users took between the provinces each day. In total, more than 12 billion mobile phone communications were recorded anonymously and linked to a province.
The researchers then compared the cellphone analysis with a highly detailed dataset on rubella incidence in Kenya. They matched; the cellphone movement patterns lined up with the rubella incidence figures.
In both of their analyses, rubella spiked three times a year: September and February primarily, and, in a few locations, rubella peaked again in May.
This showed the researchers that cellphone movement can be a predictor of infectious-disease spread.
Overall, the results were in line with the researchers’ predictions; rubella is more likely to spread when children interact with one another at school at the start of school and after holiday breaks. Across most of the country, this risk then decreases throughout the rest of the school-term months.
The only anomaly was in Western Kenya where the risk during school breaks was relatively higher than when school was in session; the data were insufficient to clearly indicate why.
“Our analysis shows that mobile phone data may be used to capture seasonal human movement patterns that are relevant for understanding childhood infectious diseases. In particular, phone data can describe within-country movement patterns on a large scale, which could be especially helpful for localized treatment.”
The results highlight how mobile phone data could be a powerful tool for understanding the critical drivers of epidemics. The researchers hope to next apply their methodology to measles and other infections shaped by human movement like malaria and cholera.
The paper, “Quantifying seasonal population fluxes driving rubella transmission dynamics using mobile phone data,” was published online on Aug. 17 in the Proceedings of the National Academy of Sciences.
About Rubella:
Rubella, also known as German measles or three-day measles, is an infection caused by the rubella virus. This disease is often mild with half of people not realizing that they are sick.
Rubella is usually spread through the air via coughs of people who are infected. People are infectious during the week before and after the appearance of the rash. Only humans are infected. Once recovered, people are immune to future infections. Testing is available that can verify immunity. Diagnosis is confirmed by finding the virus in the blood, throat, or urine.
Rubella is preventable with the rubella vaccine with a single dose being more than 95% effective. Often it is given in combination with the measles vaccine and mumps vaccine, known as the MMR vaccine.
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