Worldwide, over a billion people are living in slums. A research project led by researchers from the Swedish University of Agricultural Science is studying how diseases that spread from animals to humans in Salvador, Brazil, can be reduced. The research includes four areas in metropolitan slums with a lack of sanitation, such as open sewers, neglected waste collection, and the risk of floods.
– Rats are common in city slums. They spread severe diseases to humans, and therefore there is a great need to investigate how socio-economic and environmental factors affect how diseases spread, says Hussein Khalil, a researcher at SLU’s Department of Wildlife, Fish, and Environment who leads the project.
Residents estimate the risk of infection
It is not in direct contact between humans and rats that the disease spreads. When humans come in contact with water, sewage, or mud contaminated with urine from infected rats, the disease spreads.
Local residents have mapped their own living habits and estimated the risks of being exposed to infection. To find out who had previously been exposed to the virus, blood samples were also taken from the more than 1,300 people who participated in the study.
– We could see that people living in the poorest areas in these slums were most infected. It is also in these areas that garbage collection is most neglected. The roads are not paved either and therefore become mud in case of torrential rain and floods. People also have the longest transport routes to get to major roads in these areas, says Hussein Khalil.
Knowledge enables effective measures
Today, some government measures are underway to reduce the problems; as garbage collection and reducing the number of rats. However, the study shows that these measures are not taken consistently or in the right places to affect the spread of infection.
– By examining the driving factors behind the spread of infection, it becomes clear where the measures should be put in place to make a difference. One solution could be to focus more on improving infrastructure by building bridges, paving areas near houses, improving accessibility to major roads, and promoting local waste initiatives, says Hussein Khalil.
