How humans increased wildlife parasites

Presence of plantations, livestock significantly increases parasite diversity

August 31, 2019 09:30 pm | Updated 09:30 pm IST

Repercussions: When land use changes the internal niche is affecte too.

Repercussions: When land use changes the internal niche is affecte too.

While we humans are known to destroy wildlife habitats and make life hard for animals, a new research has now pointed out that by changing the land use patterns and introducing livestock in their ecosystem we are indirectly increasing the parasite diversity in their gastrointestinal system. However, more studies are needed to understand if this might affect their population decline.

The team looked at over 4,000 mammalian faecal samples collected from 19 forest fragments at the Anamalai Hills of the Western Ghats. These samples belonged to 23 mammalian species including tigers, deer, porcupines, lion-tailed macaques, giant squirrels and otters. By analysing the faecal samples, they concluded that the presence of plantations and livestock significantly increased the parasite diversity. The paper published in Scientific Reports says that this could be due to spillover from the livestock and humans.

“By looking at the Natural History Museum parasite database, we noted that many of the parasites are known to infect humans. However, this doesn't necessarily mean that the people currently living in Anamalai Hills are currently infected,” explains Dr. Debapriyo Chakraborty, an independent disease ecologist and first author of the paper.

One Health approach

“We need to understand that these parasites can cause a broad range of infectious diseases and it is important to study the host-parasite interactions at a community level. Also, one host can have multiple parasites and vice versa,” says Dr. Chakraborty. “Before any new interventions like land use changes or habitat modifications are being carried out complex health consequences of these large-scale human activities should be kept in mind.”

He adds that the One Heath approach needs to be used as parasites, their animal hosts and humans are a complex system which needs to be studied together.

Human settlements

Also, some studies have shown that wildlife tends to congregate near human settlements. Herbivores such as deer may find the human settlements as a source of regular food and also as a safe zone where carnivores don't enter. This could also be a reason for pathogen spillover from livestock to wildlife. The group had shown previously that high parasite prevalence was one of the reasons for the decline of endangered lion-tailed macaque populations in small and degraded forest fragments in the Western Ghats.

“When the land use changes — coffee plantation to tea plantation or when degraded forests are converted to a coffee estate — the internal niche is affected. Many epidemic diseases including the Ebola virus started finding humans as a better new host when their natural habitats were disrupted. Similarly unknown diseases could occur as a result of this anthropogenic land use changes,” explains Dr. Govindhaswamy Umapathy at the Laboratory for the Conservation of Endangered Species, Centre for Cellular & Molecular Biology (CSIR-CCMB), Hyderabad. He is the corresponding author of the work.

“By changing the existing landscape we are not just affecting the wildlife but also taking a toll on the weather and rainfall patterns. The identified eco-sensitive zones must be conserved for the wellness of all,” adds Dr. Umapathy.

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