Rhesus macaques in the northern Indian city of Shimla. Author: Dr. Krishna Balasubramaniam

A new study has revealed how infectious diseases spread among wildlife populations in areas where humans and wildlife live side by side. The study identified animals, particularly wild monkeys, that live in large groups near human settlements, which can act as “superspreaders”.

It turns out that monkeys, who interact most often with humans, are responsible for the largest outbreaks of the disease. This is because these places where monkeys and humans come into close contact, usually around food sources, can attract monkeys from different groups and subgroups. It is in these human-wildlife hotspots that monkeys interact closely with monkeys they would not regularly associate with, leading to larger outbreaks.

With the growth of world population that is settlements are increasingly encroaching on the natural habitats of wild animals, the risk from both is increasing zoonotic diseases that “throwover” from wildlife to humans and zoonotic diseases that “throwover” from humans and cause outbreaks among wildlife.

It is published in the journal Scientific reports and led by Dr Krishna Balasubramaniam of Anglia Ruskin University (ARU), the study used epidemiological computer models to simulate how infectious diseases can spread among monkeys living in cities and suburban areas of South and Southeast Asia. This is the first study to use modeling to compare the spread of disease through the social behavior of animals with the spread of disease through the tendency of animals to congregate around and interact with humans.

A team of researchers, including academics from the University of California, Davis, monitored the behavior of rhesus macaques, long-tailed macaques and caped macaques in northern India, Malaysia and southern India, respectively. In these places, wild macaques often share space with humans, and their interactions with humans often center around obtaining food.

The researchers collected detailed behavioral data on interactions between humans and individual monkeys, as well as interactions between monkeys in the same group in which humans have strong social ties. This information was collected from 10 separate groups of macaques in three locations in India and Malaysia.

These behavioral data were fed into Susceptible-Infected-Recovered (SIR) mathematical epidemiological models to simulate the impact of outbreaks of human diseases of varying transmissibility, such as influenza virus, coronaviruses, and measles virus. Computer simulations were run a total of 100,000 times for 10 groups and different human diseases, and the vulnerability of these macaque populations to human-caused disease outbreaks.

The study showed that the size of a flash was positively predicted by centrality in the group of the first infected macaque—if that individual is better connected in its social network, it will lead to a larger outbreak.

A second key finding is that the centrality of the first infected individual, based on both its congregations with other apes around humans and its interactions with humans, plays a greater role in predicting the scale of an outbreak than how important it is in to his group. .

This is because macaques may congregate around human-provided food near other macaques that they would not otherwise interact with as often. The study found that such situations create additional pathways for disease transmission and thus lead to larger outbreaks.

The researchers believe that this work could be vital for identifying which individual monkeys are the most sociable and most likely to gather around and interact with humans. Vaccination or other types of medical treatment can potentially protect macaque populations and people in the areas where they live. closeness.

Dr Krishna Balasubramaniam, Lecturer in Conservation and Animal Behavior at Anglia Ruskin University (ARU), said: “Covid-19 has highlighted the importance of understanding the transmission of infectious diseases among wild animal populations in urban and suburban areas. Population growth has increased human-wildlife contact, and these human-wildlife interactions are widely recognized as “hotspots” for disease transmission among species.

“Our research focused on the potential impact of a human-transmitted disease spreading through wild macaque populations. Being very close to humans, macaques are very vulnerable to the same diseases that infect humans. Indeed, previous work by other researchers has shown that macaques can can be infected by human gastrointestinal and respiratory pathogens.Here we show how respiratory pathogens in particular can spread through macaque populations, and in particular how their behavior can influence such spread.

“Through field work and modeling, our research has identified which people are most likely to act as a ‘super spreader’ of the disease, leading to larger outbreaks. How central an individual was to its group affected the size of the outbreak, but interestingly, the strongest predictor of whether a macaque would cause a large outbreak was its tendency to congregate around people with macaques from other subgroups.

“Human-provided food sources can act as a ‘honey pot’ and lead macaques to come into very close contact with individuals with whom they might have less contact, such as monkeys from other families or subgroups.

“In addition to being ‘superspreaders’ within their own species, these individuals with more human contact also pose the greatest risk to interspecies transmission of disease events, either from humans to wildlife, or vice versa. These would be the most effective targets for disease control strategies such as vaccination or antimicrobial treatment.”

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Additional information:
Effects of co-human interaction and social interactions with conspecifics on the risk of zoonotic outbreaks in wildlife populations, Scientific reports (2022).

Citation: Mapping Disease Risk in Human-Wildlife Hotspots (2022, October 3) Retrieved October 3, 2022, from https://phys.org/news/2022-10-disease-human-wildlife-hotspots. html

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