A new study found that as East Africa is converting the wilderness into farmlands to address the issue of food shortage, the people are increasing their risks of plague.
Researchers at the University of California, Santa Barbara, analyzed the rats in northern Tanzania. The team focused on this area because of history of plague outbreaks. Over the past few decades, this region has converted almost 70 percent of its land area into farmlands.
The findings showed that there is twice the number of African rats (Mastomys natalensis) in Tanzania compared to the neighboring wilderness areas. African rats are carriers of plague and the virus that causes Lassa fever, which is similar to Ebola. The virus can easily be transmitted to humans who have contact with feces or urine of animals accessing grain stores in houses.
"We found that introducing maize production in natural areas appears to create a perfect storm for plague transmission," Hillary Young, study leader and a community ecologist at the University of California, Santa Barbara, said in a news release. "The presence of the crop as a food source caused a surge in the population of a rat species known to carry plague. Local farmers often then store this harvested corn next to or inside their homes--baiting in the hungry field rats and increasing opportunities for human infection."
"These kinds of conditions are what breed outbreaks," Young said.
The researchers are worried that the farmers, in an attempt to protect their crops, are actually attracting the rats by storing the maize in their houses.
"People in these communities tend to store their maize in their houses, to protect it, but that also has the effect of attracting these rats," Young said. "The rats that persist in human areas are also particularly competent hosts for plague, as well as likely to interact with humans. Together, these changes increase the opportunities for humans to be bitten by plague-infected fleas."
Human plague has been a public health concern for Tanzania. The health officials have recorded about 8,490 cases and 675 deaths due to plague outbreaks between 1980 and 2011.
The study was published in the Feb. 23 issue of the American Journal of Tropical Medicine and Hygiene.
