By
Peter Ruegg
ETH
Zurich – September 19, 2019 -- An
international team of researchers led by ETH has shown that
antimicrobial-resistant infections are rapidly increasing in animals in low and
middle income countries. They produced the first global [map] of resistance
rates, and [they] identified regions where interventions are urgently needed.
The
world is experiencing unprecedented economic growth in low- and middle-income
countries. An increasing number of people in India, China, Latin America and
Africa have become wealthier, and this is reflected in their consumption of
meat and dairy products. In Africa, meat consumption has risen by more than
half; in Asia and Latin America it is up by two-thirds.
To
meet this growing demand, animal husbandry has been intensified, with among
other things, an increased reliance on the use of antimicrobials. Farmers use
antimicrobials to treat and prevent infections for animals raised in crowded
conditions but these drugs are also used to increase weight gain, and thus
improve profitability.
This
excessive and indiscriminate use of antimicrobials has serious consequences:
the proportion of bacteria resistant to antimicrobials is rapidly increasing
around the world. Drugs are losing their efficacy, with important consequences
for the health of animals but also potentially for humans.
Mapping
resistance hotspots
Low-
and middle income countries have limited surveillance capacities to track
antimicrobial use and resistance on farms. Antimicrobial use is typically less
regulated and documented there than in wealthy industrialized countries with
established surveillance systems.
The
team of researchers led by Thomas Van Boeckel, SNF Assistant Professor of
Health Geography and Policy at ETH Zurich, has recently published a map of
antimicrobial resistance in animals in low- and middle-income countries in the
journal Science.
The
team assembled a large literature database and found out where, and in which
animals species resistance occurred for the common foodborne bacteria Salmonella,
E. coli, Campylobacter and Staphylococcus.
According
to this study, the regions associated with high rates of antimicrobial
resistance in animals are northeast China, northeast India, southern Brazil,
Iran and Turkey. In these countries, the bacteria listed above are now
resistant to a large number of drug that are used not only in animals but also
in human medicine. An important finding of the study is that so far, few
resistance hotspots have emerged in Africa with the exception of Nigeria and
the surroundings of Johannesburg.
The
highest resistance rates were associated with the antimicrobials most
frequently used in animals: tetracyclines, sulphonamides, penicillins and
quinolones. In certain regions, these compounds have almost completely lost
their efficacy to treat infections.
Alarming
trend in multi-drug resistance
The
researchers introduced a new index to track the evolution of resistance to
multiple drugs: the proportion of drugs tested in each region with resistance
rates higher than 50%. Globally, this index has almost tripled for chicken and
pigs over the last 20 years. Currently, one third of drugs fail 50% of the time
in chicken and one quarter of drug fail in 50% of the time in pigs.
“This
alarming trend shows that the drugs used in animal farming are rapidly losing
their efficacy,” Van Boeckel says. This will affect the sustainability of the
animal industry and potentially the health of consumers.
It
is of particular concern that antimicrobial resistance is rising in developing
and emerging countries because this is where meat consumption is growing the
fastest, while access to veterinary antimicrobials remains largely unregulated.
“Antimicrobial resistance is a global problem. There is little point in making
considerable efforts to reduce it on one side of the world if it is increasing
dramatically on the other side,” the ETH researcher says.
Input
from thousands of studies
For
their current study, the team of researchers from ETH, Princeton University and
the Free University of Brussels gathered thousands of publications as well as
unpublished veterinary reports from around the world. The researchers used this
database to produce the maps of antimicrobial resistance.
However,
the maps do not cover the entire research area; there are large gaps in particular
in South America, which researchers attribute to a lack of publicly available
data. “There are hardly any official figures or data from large parts of South
America,” says co-author and ETH postdoctoral fellow Joao Pires. He said this
surprised him, as much more data is available from some African countries ,
despite resources for conducting surveys being more limited than in South
America.
Open-access
web platform
The
team has created an open-access web platform resistancebank.org to share
their findings and gaher additional data on resistance in animals. For
example, veterinarians and state-authorities can upload data on resistance in
their region to the platform and share it with other people who are interested.
Van
Boeckel hopes that scientists from countries with more limited resources for
whom publishing cost in academic journal can be a barrier will be able to share
their findings and get recognition for their work on the platform. “In this
way, we can ensure that the data is not just stuffed away in a drawer” he says,
“because there are many relevant findings lying dormant, especially in Africa
or India, that would complete the global picture of resistance that we try to
draw in this first assessment. The platform could also help donors to identify
the regions most affected by resistance in order to be able to finance specific
interventions.
As
meat production continues to rise, the web platform could help target interventions
against AMR and assist a transition to more sustainable farming practices in
low- and middle-income countries. “The rich countries of the Global North,
where antimicrobials have been used since the 1950s, should help make the
transition a success,” says Van Boeckel.
The
research was funded by the Swiss National Science Foundation and the Branco
Weiss Fellowship.
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