What did the chicken on your plate eat? Beware, it could be fatal

Thursday May 07 2015

Beneath the growing demand for the lean white meat are deadly health risks associated with the abuse of antibiotics, mainly on medium-and large-scale chicken rearing farms, according to recent studies. Chicken nuggets at a McDonald’s fast food restaurant in Rennes, France. FILE PHOTO | TEA GRAPHIC | NATION MEDIA GROUP

The demand for chicken has been growing in East Africa, especially among the health-conscious middle class who prefer lean white meat to the cholesterol-rich red meat.

But beneath the growing demand for the delicacy are deadly health risks associated with the abuse of antibiotics, mainly on medium-and large-scale chicken rearing farms, according to recent studies.

Scientists say farmers are arbitrarily giving the birds antibiotics to stimulate growth in order to get them to reach “the slaughter weight within 35 days of hatching,” and prevent illness in confined flocks.

Researcher Patrick Vudriko, who is currently based in Japan, said studies done in various countries found that poultry farmers prefer human antibiotics because they can easily buy them over the counter, and that they are normally cheaper than veterinary formulations.

“Obviously farmers have no idea about physiology thus they would not know how to use the drugs,” said Dr Vudriko, adding that some farmers were using antiretroviral drugs to fatten broilers quickly.

But on the flip side, the farmers risk creating drug-resistant “super bugs,” putting the lives of chicken consumers at risk. Superbugs are bacteria that are resistant to different types of antibiotics.


“The misuse of antibiotics is pushing us to a point where common infections could become a death trap because patients will no longer respond to the drugs we have,” said Nairobi-based veterinary doctor Gregory Githinji. “This is how resistant E coli and salmonella bacteria are finding their way into human bodies.”

Last year, the Kenya Medical Research Institute (Kemri) released a study on the safety of raw chicken sold in Nairobi. The study, published in the BMC Research Notes journal, exposed the risks consumers face every day by eating such meat.

The study found that retail chicken in Nairobi was not only highly contaminated, but that it also contained potentially pathogenic multidrug-resistant strains of E coli.

Ideally, the bacterium commonly found in the intestines of humans and other animals causes no harm, but the point of concern is the dangerous strains that have developed in recent times — capable of causing severe food poisoning and even death if not well treated.

“Seventy-five per cent of the isolates were resistant to at least one of the 12 antibiotics tested, with resistance to tetracycline being the highest at 60.3 per cent. In addition, 40.4 per cent E coli isolates were positive for the 10 virulence genes tested,” the scientists concluded in the Kemri study.

Salmonella, another group of bacteria that are a common cause of food poisoning, are also becoming resistant to antibiotics. Salmonella is found in contaminated animal products like meat, eggs and milk. Like E coli, it can cause diarrhoea, vomiting, stomach cramps and severe fever.

Many scientists believe that the results from the study are just the tip of the iceberg, and that the problem is bigger and not confined to Nairobi, but affects other parts of East Africa also.

A study conducted in 2010 on faecal samples from broiler chickens in northern and central Uganda for example, discovered a high percentage of E coli isolates from samples collected in Lira and Kampala districts. In Lira, 90.8 per cent of the samples tested were infected with E coli, while 73 per cent tested positive in Kampala. The study was published in Medwell Journals.

“A total of 182 E coli were tested for their sensitivity to six antimicrobials — tetracycline, ciprofloxacin, chloramphenicol, ampicillin, cotrimoxazole and gentamicin. Overall, 168 isolates showed resistance to at least one antimicrobial,” the study concluded.

An antimicrobial is any substance of natural, semisynthetic or synthetic origin that kills or inhibits the growth of micro-organisms but causes little or no damage to the host. All antibiotics are antimicrobials.

Resistant bacteria

In the Ugandan study, some of the bacteria tested were resistant not just to one drug but three; for example, ampicillin and tetracycline in combination with cotrimoxazole.

The challenge is that all three are important human drugs in East Africa’s health sector, and are used to treat various bacterial infections that normally affect vital organs such as lungs (pneumonia and bronchitis), genitals, skin and the urinary system.

Another study conducted in Tanzania in 2012 on the awareness of human health risks associated with the use of antibiotics found that livestock keepers in peri-urban areas of Dar es Salaam and Morogoro frequently gave their animals antibiotics without proper guidelines.

The most commonly used antibiotics were tetracycline, sulphadimidines and penicillin-streptomycin. Again, all the drugs are important in human medicine.

Equally, a recent study from seven European countries — Norway, Sweden, Denmark, Austria, Switzerland, the Netherlands, and Belgium — showed a strong correlation between consumption levels for eight classes of antimicrobials and the prevalence of antimicrobial-resistant E coli in pigs, poultry and cattle.

The World Health Organisation says drug use in farm animals plays a “significant role” in spreading antibiotic-resistant salmonella and campylobacter infections to humans. Campylobacter infections are caused by bacteria and are spread by eating contaminated food.

In a new report dubbed Worldwide country situation analysis: Response to antimicrobial resistance, the organisation says there are major gaps in actions needed to prevent the misuse of antibiotics and reduce spread of antimicrobial resistance.

“Without urgent action, the world is heading for what is being termed a post-antibiotic era in which common infections and minor injuries that have been treatable for decades may once again kill, and we will lose the ability to treat a range of serious conditions such as bloodstream infections, pneumonia, tuberculosis, malaria, HIV,” said WHO co-ordinator for antimicrobial resistance, Charles Penn. 

Another study of global trends in antimicrobial use in food animals, conducted by scientists from the Nairobi-based International Livestock Research Institute, Princeton University, Université Libre de Bruxelles and Centre for Disease Dynamics, Economics & Policy, found that the rise in the use of antimicrobials in farm animals is concentrated mainly in low and middle income countries.

The study published in the Proceedings of the National Academy of Science, said the global average annual consumption of antimicrobials per kilogramme of animal produced was 45 milligrammes per kilogramme (mg/kg) for cattle, 148 mg/kg for chicken and 17mg/kg for pigs.

The scientists also estimated that the global consumption of antimicrobials in the livestock sector is expected to increase by 67 per cent (from 63,151 tonnes to 105,596 tonnes) between 2010 and 2030, as more farmers in developing countries seek their use.

“Up to one-third of the increase in consumption in livestock is imputable to shifting production practices in middle-income countries where extensive farming systems will be replaced by large-scale intensive farming operations,” the scientists said.

The study found that the largest increase in the use of antibiotics in livestock will be in the BRICS countries (Brazil, Russia, India, China and South Africa), where antimicrobial consumption will be 99 per cent, that is, up to seven times the projected population growth in this group of countries.

“It is not only those in BRICS that should be concerned about the future. East Africans too should be concerned going by the studies on the abuse of antibiotics in the region,” said Dr Githinji.

Dr Githinji and others are already worried that Africa could go the US way where the use of antibiotics has reached unprecedented levels.

In the US, for example, antimicrobial use in food animals is estimated to account for 80 per cent of the nation’s annual consumption, a significant portion of which involves antimicrobials that are considered important in human medicine

So, why do many farmers prefer using antibiotics on their livestock even when they are not sick?

Farmers in East Africa and other regions in the world use antibiotics to prevent any anticipated disease and to promote the growth of their livestock. Some of them argue that if they do not do this, their animals will die.

According to the Kemri study, a common practice among broiler chicken producers in urban areas is to add antibiotics to the commercial feeds or drinking water of the birds, thereby unnecessarily exposing them to human medicines.

Veterinary scientists say the doses are normally at the low levels conducive to the growth of the “superbugs” that have managed to gain resistance to conventional medicines used in hospitals to treat people.

“The problem is that we are beginning to see a situation where low doses of antibiotics were part of the standard diet for some livestock in East Africa. This is dangerous,” said Dr Githinji.

But recently, scientists with the US Centres for Disease Control and Prevention (CDC) warned that the use of any type of antibiotic, not only those medically important to humans, contributes to resistance. According to CDC, whenever an antibiotic is administered, it kills weaker bacteria and enables the strongest to survive and multiply through natural selection.

“The other fear is that the superbugs could also develop cross-resistance to some of the antibiotics important to humans,” said Dr Githinji. “We must protect the antibiotics we have for the current and future generation.”

Additional reporting by Christabel Ligami