Common livestock dewormers may be failing across Africa, ILRI reports

KENYA – Commonly used livestock dewormers may be losing effectiveness across Africa as resistance among parasitic worms increases, threatening animal productivity, feed efficiency and farmer incomes, according to new research led by the International Livestock Research Institute (ILRI) in collaboration with the University of Nairobi.

The study, published in BMC Veterinary Research in October 2025, highlights growing concerns about anthelmintic resistance (AHR), in which parasitic worms survive treatment and continue to spread. 

The findings point to widespread but under-documented resistance in cattle, sheep and goats, driven largely by the improper and indiscriminate use of deworming drugs without veterinary oversight.

Gastrointestinal nematodes, including Haemonchus and Trichostrongylus, remain a major burden in grazing systems across Africa. 

These parasites reduce feed intake efficiency, impair nutrient absorption and significantly lower productivity. 

In sheep alone, infections can lead to a 58% reduction in weight gain, a 90% loss in wool production, and a 78% decline in milk yield, according to the study.

Despite the scale of the problem, researchers identified only 28 relevant studies across nine African countries, most published before 2014, underscoring a major data gap in understanding the extent of resistance across the continent. 

Available evidence indicates resistance to commonly used drug classes, particularly benzimidazoles and macrocyclic lactones, raising concerns about the long-term effectiveness of current parasite control strategies.

Globally, parasitic infections already account for billions in losses, with Europe alone losing more than US$2 billion annually and spending an additional US$41 million managing resistance. 

While comparable continent-wide figures are lacking for Africa, the impact is expected to be significant given the region’s heavy reliance on livestock for livelihoods and food security.

Researchers warn that AHR remains largely overlooked in policy, funding priorities and national surveillance programmes. 

They call for increased investment in diagnostics, standardised monitoring systems and improved farmer awareness to promote responsible drug use and integrated parasite management practices, including grazing control.

Climate change is expected to intensify the challenge. 

Reports by the Intergovernmental Panel on Climate Change and the Food and Agriculture Organization have already identified rising temperatures and changing rainfall patterns as key drivers of increased parasite prevalence, potentially accelerating the spread of resistant strains.

Alternative feed solutions gain attention amid productivity losses

As parasite-related productivity losses increase, stakeholders are also exploring feed-based solutions to improve livestock resilience and reduce dependence on conventional inputs. 

In Nigeria, industry players are pushing to scale Black Soldier Fly larvae (BSFL) as an alternative protein source to strengthen feed systems and reduce costs.

At a national roundtable hosted by the ILRI in Ibadan, stakeholders called for policy reforms, increased investment and stronger coordination to accelerate the adoption of insect-based feed solutions. 

The discussions highlighted BSFL’s potential to convert organic waste into high-protein feed within 10 to 14 days, with protein content ranging from 40% to 45%, making it a viable substitute for conventional ingredients in poultry, fish, and pig diets.

“Black soldier fly larvae can play a critical role in addressing Nigeria’s feed crisis, but the key challenge remains scaling production,” said ILRI Nigeria country representative Dr Tunde Amole, noting that demand from feed manufacturers is already growing.

However, constraints remain across the value chain. 

Stakeholders cited fragmented production systems, lack of standardisation, limited access to financing and equipment, and underdeveloped regulatory frameworks as key barriers to large-scale adoption. 

Despite these challenges, Nigeria’s tropical climate and abundant organic waste streams position the country as a strong candidate for year-round BSFL production.

The push toward alternative proteins reflects a broader shift in the feed industry as producers seek to improve efficiency and resilience. 

With parasitic infections reducing feed utilisation and increasing production costs, integrating innovative feed ingredients alongside improved animal health management is becoming increasingly important.

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