Lecture 3, Antimicrobial resistance Flashcards
- What is anthelmintic resistance (AR)?
Anthelmintic resistance (AR) is the heritable ability of the parasite to tolerate a normally effective dose of an anthelmintic.
The parasite is considered resistant if it survives exposure to the standard recommended dose of the anthelmintic and the ability to survive is passed on to the parasites offspring.
- What is refugia?
When animals are treated with deworming medicine, some parasites survive because they are not exposed to the drug. These survivors are in the “refugia.”
Refugia management involves making sure these surviving parasites have a chance to infect animals again soon after the treatment.
- Why is there an apparent global discrepancy in parasite resistance between livestock and pets?
The answer lies within the concept of “refugia,” a term used to describe the portion of worms not exposed to anthelmintic drugs.
In the realm of livestock, there’s minimal refugium. Typically, entire herds or flocks receive treatments concurrently, leaving little room for parasites to escape drug pressure.
The situation is different for our pets. A multitude of wildlife refugia, including foxes, wolves, and raccoons, exists. Moreover, pets are usually treated individually or in small groups within households, without coordinated efforts in terms of geography, timing, or the class of anthelmintic used.
Name drivers of resistance. (5)
There are five key factors which define the rate at which anthelmintic resistance develops:
- Proportion of resistant worms on a farm.
- Frequency of anthelmintic use.
- Efficacy of each treatment.
- Proportion of the total worm population in the animal at the time of treatment.
- Dilution of any worms that survive treatment with unselected worms.
There are currently no WOAH guidelines on prudent use of
antiparasitic drugs and no standard setting guidelines on antiparasitics.
The “in refugia” population is
the proportion of the roundworm population that is unexposed to anthelmintic treatment.
Why might the management of anthelmintic resistance differ between livestock and pets?
Pets often receive more individualized treatment regimens, contributing to the preservation of parasite refugia.
AMR can be intrinsic or acquired; the latter can occur through mutations, or in the case of bacteria by
the acquisition of deoxyribonucleic acid (DNA) from different microorganisms, via horizontal gene transfer (HGT) of mobile genetic elements (MGEs).
AMR is a significant threat to, not only human and animal
health, but also?
food security, economic development and equity within societies.
LIC, LMIC
low and middle income countries
AMR challenges are closely linked to the triple planetary crisis of
climate change, biodiversity
loss and pollution and waste, all of which are driven by human activity, including unsustainable consumption and production patterns.
Biological and chemical pollution sources
containing antimicrobials contribute to
resistance development.
When antimicrobials are released into the
environment, they can select for resistant
microorganisms and resistance emergence
Human exposure to AMR from the environment can take place following
consumption of food and/or water that have become contaminated by resistant microorganisms.
AMR requires a response based on a concerted
systems approach, such as
‘One Health’,
which recognises that the health of people,
animals, plants and the environment are closely
linked and interdependent
Three economic sectors and their value chains are key drivers of AMR development and spread in the environment:
pharmaceuticals and other chemical
manufacturing, agriculture and food production, and healthcare