Children standing in trash and looking at houses in Kibera, Kenya, East Africa. Kibera is the largest slum in Nairobi, the largest urban slum in Africa, and the third largest in the worldCredit: hadynyah/ E+/ Getty Images
A lack of biodiversity could be fuelling the transfer of disease-causing pathogens from animals to humans in rapidly developing urban centres, a study in PNAS has shown. Urban designers should consider the potential for pathogen spillover, researchers say.
The study, by a team of veterinarians and epidemiologists from the International Livestock Research Institute (ILRI), in Nairobi, the University of Nairobi, Kenya Medical Research Institute, National Museums of Kenya and Kenya Wildlife Service was based on genetic relationships between E. coli bacteria samples collected from a group of more than 2,000 people, livestock and urban wildlife from 33 locations across Nairobi.
According to the study people become more central in wildlife networks when inhabiting areas that support low diversity of wildlife species, thereby increasing wildlife-human transmission potential. Loss of biodiversity, the researchers say, largely occurs with gradients of increasing urbanisation in the tropics and leads to rapid increase of synanthropes such as rodents and passerine birds at the expense of other wildlife. "These species not only live in closer association with people but are also more competent reservoirs for zoonotic pathogens and should be prioritised for disease surveillance and control," the team says.
“The more you build streets and roads, the more you create an environment suitable for certain species such as black rats and certain kind of birds that are good reservoirs of human pathogens,” said Eric Fevre, the study’s senior author from ILRI, and the University of Liverpool.
“We have severely neglected to think about the healthcare of the urban ecosystem. We just build because there is a demand,” Fevre told Nature Africa.
He said a city like Nairobi is in a biodiverse natural environment and urban planners need to think about its ecology before infrastructure is designed.Additional partners in the study included researchers from the University of Edinburgh, the University of Liverpool, University of Minnesota, University of Oxford, University of Southampton, Hokkaido University Columbia University, University of Milan and Food and Agriculture Organization of the United Nations.
“We can’t really redesign urban environments to completely eliminate the risk of disease spillover,” said the study’s lead author, James Hassell, from the University of Liverpool. “But we want to detect these diseases quickly and minimize their impact, and to do that, the focus needs to be on access to quality healthcare that can diagnose and identify new pathogens.”
