Study reveals most dangerous zoonoses

Carried out by the International Livestock Research Institute (ILRI), the Institute of Zoology and the Hanoi School of Public Health in Vietnam, the study found that the “unlucky” 13 zoonoses were mainly prevalent in areas of poverty in developing countries.

It revealed that diseases such as cyst-causing tapeworms, avian flu and Rift Valley fever were all increasing due to the “exploding demand for livestock products”​ and stated that nearly 60% of all human diseases and 75% of all emerging infectious diseases are zoonotic.

Lead researcher Delia Grace, a veterinary epidemiologist and food safety expert with the ILRI in Kenya, said that the biggest finding in the report was that opportunities for stopping zoonoses lie in three notable countries - Ethiopia, Nigeria and India.

“These three countries have the highest number of poor livestock keepers, the highest number of malnourished people, and are in the top five countries for both absolute numbers affected with zoonoses and relative intensity of zoonoses infection. These findings allow us to focus on the hotspots of zoonoses and poverty, within which we should be able to make a difference,”​ she said.

Intensification​

The research also revealed the impact of intensification on the spread of zoonoses. Director of of the research programme on Agriculture for Nutrition and Health, John McDermott said that the high levels of infection in poor countries were caused by the ever-intensifying production and processing of livestock and food.

He said: “Historically, high-density pig and poultry populations have been important in maintaining and mixing influenza populations. A major concern is that as new livestock systems intensify, particularly small and medium-sized pig production, more intensive systems will allow the maintenance and transmission of pathogens. A number of new zoonoses, such as Nipah virus infections, have emerged in that way.”​

Intensively farmed poor areas were also the areas where researchers found a “massive underreporting”​ of zoonoses and animal disease. The research found that in sub-Saharan Africa, 99.9% of livestock losses are not reported.

Previous research had reviewed 56 zoonoses, which are said to be responsible for around 2.5bn cases of human illness and 2.7m human deaths per year. This more detailed study of the 13 zoonoses cited as being the most important was based on an analysis of 1,000 surveys of more than 10m people, 6m animals and 6,000 food or environmental samples.