Dr Pamela Woods
The term “anti-microbial resistance” or “AMR’ is in the news worldwide these days.
We have not heard much about this in Zimbabwe yet and it is important that we get the correct information so that we can change our behaviours if we need to, and also to reduce the worry that comes from incomplete messages.
What are Anti-microbials and how does resistance occur?
Anti-microbial medicines including anti-biotics are an important tool in the treatment of various infectious diseases of man and animals. They act by killing or stopping disease-causing germs, such as bacteria, fungi, protozoa, viruses and parasites that cause disease in humans and animals.
Anti-microbial resistance (AMR) is a situation where disease-causing germs are able to withstand attack by anti-microbial drugs normally recommended for treatment, such as anti-biotics, anti-fungals, anti-virals, and anti-malarials, leading to loss of effectiveness in treating diseases.
While drugs for animal use are required to be labelled as such, many of the main ingredients in veterinary drugs are the same as those designed for human use. AMR occurs naturally, but over-use, under-dosage and mis-use of anti-microbials in human and animal health, agriculture and application in the environment, can speed this phenomenon up, resulting in ineffectiveness of previously successful treatments of human and animal diseases.
Over-the-counter sale of anti-biotics to the public, without direct professional supervision of clinical cases by medical or veterinary doctors can result in improper use of anti-microbials, risking the development of AMR.
Anti-microbial residues also easily develop when anti-microbials are routinely used in feeds to suppress the presence of disease-causing micro-organisms, risking the development of AMR. Use of anti-microbials in feeds or water is a practical way to treat some diseases in poultry or aquaculture systems where individual animal treatment would be impossible.
These should be veterinary-supervised only for specific problems and duration. It is also important to ensure that time is allowed between stopping the medicine treatment and starting harvesting any animal products for human consumption. This is called a “withdrawal period” and gives time for the medicine to leave the bird or fish’s body and for it to become safe for people to eat without increased risk of developing AMR.
Because of the wide range of health problems for which we need anti-microbials , AMR is a phenomenon worth pondering about in order to guarantee their sustainable effectiveness.
Consequences of AMR
Since anti-microbials were discovered in the 1920s, hundreds of them have been developed to combat emerging infectious diseases as well as to overcome the sequential development of AMR. The development of each new anti-microbial, however, entails huge research cost for which the patient must pay. Development of new anti-microbials has, however, slowed down significantly with virtually no new anti-microbial being developed since 1987.
This means that if the emergence of AMR is allowed to continue, there might soon be an increase in diseases, which cannot be cured, from which people will die unnecessarily. Animal-source food systems will become insecure, as disease-related losses, of which there are many, will erode production efficiency. A significant proportion of infectious animal diseases also affect people and others are carried in the food chain, leading to major public health problems.
The molecular determinants of resistance in micro-organisms can also be transferred within families of micro-organisms affecting large populations of micro-organisms in relatively short periods.
Given the importance of anti-microbial use in health and veterinary delivery systems, the development of AMR will reverse many development gains in which health delivery systems have had a part to play. The health systems could also become overburdened.
Responsible and Prudent Use of anti-biotics and other anti-microbials
The optimal use of anti-microbial medicines is realised when they are used exactly as advised by the doctor, nurse or veterinary professional in terms of duration and dosage. If they are incorrectly used by not having the correct dose rate or by not completing the full treatment period, it becomes more likely that drug resistance will occur. Treatment regulations require that each dispensed medicine is appropriately labelled on the bottle, box or sachet, indicating dose frequency and interval of use.
These are intended to achieve “cure” by the time the treatment course ends. For food animals, clear instructions will normally be included indicating the length of time from the last day of treatment after which the animals can be harvested for food.
Alternatives to anti-microbial use can also assist in the slowing down of the development of AMR. Greater reliance on preventive actions such as general hygiene, vector and pest control management during livestock production, or the use of preventive vaccines may greatly reduce dependence on anti-microbials. Strict bio-security regimes applicable to intensive production systems can also result in the greatly reducing dependence on anti-microbials, especially anti-biotics.
Because of the close interplay between disease-causing organisms, their relatives in the environment, the human subject and animal life, AMR links animal and human health and the environment and as such is a “One Health” issue. Veterinary and human medicine and environmentalists must share responsibilities for preventing anti-microbial abuse and slowing down AMR development.
This requires clear policies and a strategic action plan meant to arrest the development of the phenomenon. Above all, awareness by animal keepers, medical and veterinary personnel, the pharmaceutical industry and pharmacists as well as traders and consumers is a key component in slowing down the growing development of AMR. A multi-sectoral national action plan towards responsible and prudent use of anti-microbials is, therefore, a necessity, to see us into the future in which anti-microbial use is more sustainable
Ongoing activities on AMR
Taking the cue from the close collaboration which has emerged between the World Organisation for Animal Health (OIE), the United Nations’ Food and Agriculture Organisation and the World Health Organisation on the AMR issue, in a true “one health” mode, the Department of Livestock and Veterinary Services of the Ministry of Agriculture, Mechanisation and Irrigation Development and the Department of Epidemiology and Disease Control of the Ministry of Health and Child Care have begun to collaborate.
Some of the key issues to be tackled will be to define the extent of the AMR problem nationally, establishing a surveillance programme on the use of anti-microbial agents and development of AMR. These should form a basis for defining national objectives and a National AMR Action Plan contributing to a global strategy. A national AMR working group is currently at work on this.
Dr Pamela Woods is a senior lecturer in Animal Science at the University of Zimbabwe
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