Ruminant livestock are important hosts of Leptospira in northern Tanzania
Leptospirosis, which affects more than one million people worldwide each year, is known to be transmitted to humans from a wide range of animals. Now, researchers reporting in PLOS Neglected Tropical Diseases have discovered that more than 7 percent of the cattle and 1 percent of sheep and goats in local slaughterhouses in northern Tanzania are infected with Leptospira bacteria.
Kathryn Allan, of the University of Glasgow, and colleagues tested rodents, cattle, goats and sheep for Leptospira infection. Animals were sampled in the catchment areas of two hospitals that had high prevalence of patients with leptospirosis. Small samples of kidney tissue were collected and used to test for the bacteria.
Leptospira infection was not detected in any of the 384 samples from trapped rodents. In contrast, Leptospira was detected in kidney samples from 7.1% of cattle, 1.2% of goats, and 1.1% of sheep. As well as having a high prevalence of infection, cattle were found to be carrying four different types of Leptospira bacteria, all of which have the potential to cause disease in people.
“Our study makes a substantial contribution to the growing body of evidence that livestock, especially cattle, play an important role in the epidemiology of human leptospirosis in sub-Saharan Africa,” the researchers say.
In another study, also published in PLOS Neglected Tropical Diseases, researchers investigated risk factors for human leptospirosis in northern Tanzania. They found exposure to cattle was associated with acute infection.
Michael Maze of the University of Otago, New Zealand, and colleagues enrolled people with fever from two hospitals in Moshi, Tanzania from 2012 through 2014. Each participant was tested for leptospirosis, and administered a survey on risk behaviours over the past 30 days, including exposure to livestock, rodents, and surface water.
The researchers identified 24 acute cases of leptospirosis, 252 seropositive participants, and 592 controls. Rice farming, cleaning cattle waste, feeding cattle, and farm work were all positively associated with acute leptospirosis. Smallholder farming – which may be associated with substantial exposure to both livestock and rodents – as well as frequent sightings of rodents in one’s kitchen or food store – was associated with seropositivity.
“Our findings suggest that control of Leptospira infection in livestock could play a role in preventing human leptospirosis in Africa,” the researchers say.
Assessment of animal hosts of pathogenic Leptospira in northern Tanzania by Kathryn J. Allan, Jo E. B. Halliday, Mark Moseley, Ryan W. Carter, Ahmed Ahmed, Marga G. A. Goris, Rudy A. Hartskeerl, Julius Keyyu, Tito Kibona, Venance P. Maro, Michael J. Maze, Blandina T. Mmbaga, Rigobert Tarimo, John A. Crump and Sarah Cleaveland, published in PLoS Neglected Tropical Diseases (2018) 12(6): e0006444, doi: 10.1371/journal.pntd.0006444
Risk factors for human acute leptospirosis in northern Tanzania by Michael J. Maze, Shama Cash-Goldwasser, Matthew P. Rubach, Holly M. Biggs, Renee L. Galloway, Katrina J. Sharples, Kathryn J. Allan, Jo E. B. Halliday, Sarah Cleaveland, Michael C. Shand, Charles Muiruri, Rudovick R. Kazwala, Wilbrod Saganda, Bingileki F. Lwezaula, Blandina T. Mmbaga, Venance P. Maro and John A. Crump published in PLoS Neglected Tropical Diseases (2018) 12(6): e0006372, doi: 10.1371/journal.pntd.0006372