A silent health crisis affecting the lifeline of urban economies in tropical developing countries
In the bustling streets of many tropical developing countries, urban working equines—horses, donkeys, and mules—are a lifeline for the economy. They pull heavy carts through crowded markets, transport goods and people, and provide a vital source of income for their owners.
Yet, beneath their steadfast exterior, a silent and widespread health crisis looms. Gastrointestinal helminths (parasitic worms) are among the most common and debilitating health threats these animals face. Infections sap their strength, cause poor body condition, and reduce their precious work output, creating a cycle of suffering and economic hardship 5 . Understanding this hidden burden is the first step toward easing it.
Reduced work output and productivity due to parasitic infections
Poor body condition, weakness, and increased susceptibility to other diseases
Chronic suffering and reduced quality of life for working animals
A diverse community of parasitic worms can inhabit the digestive tracts of equines. The most prevalent and economically significant groups found in urban working animals include:
Often considered the most significant equine parasites, strongyles are divided into large and small species. The larval stages of large strongyles, particularly Strongylus vulgaris, migrate through blood vessels, causing inflammation, blood clots, and potentially life-threatening colic. Small strongyles (cyathostomins) can become dormant in the gut wall, later emerging in large numbers to cause severe diarrhea and weight loss 5 .
Female pinworms lay their eggs around the anus, causing intense itching and tail-rubbing. While less deadly than other parasites, they contribute to the animal's discomfort and poor welfare 5 .
The urban environment creates a perfect storm for the transmission and persistence of these parasites.
When numerous animals are kept in close quarters, the concentration of parasite eggs in the environment skyrockets, increasing every animal's risk of infection 7 .
Many owners lack the resources or knowledge for effective parasite control. Access to veterinary care and anthelmintic drugs (dewormers) may be limited or unaffordable 2 .
Inadequate manure management means pastures and holding areas become heavily contaminated with infective parasite larvae and eggs, ensuring constant re-exposure 7 .
The physical demands of pulling heavy carts in challenging conditions can suppress the immune system, making animals more susceptible to parasitic infections and their negative consequences 1 .
Eggs in Environment
Larval Development
Host Infection
Eggs Shed in Feces
To truly grasp the scale of the problem, let's examine a pivotal study conducted in the Gamo Gofa Zone of Ethiopia, a region reliant on its equine population.
Researchers employed a cross-sectional study design, collecting and analyzing fecal samples from 470 randomly selected equines (horses, mules, and donkeys) across different agro-ecological zones 3 . The process was methodical:
The findings were stark. The overall prevalence of helminth infection was a staggering 90.4% 3 . This means that the vast majority of working equines in the region were infected with at least one type of parasitic worm.
| Parasite Type | Prevalence | Key Facts |
|---|---|---|
| Strongyles | 65.1% | The most common group; includes highly pathogenic species |
| Parascaris equorum | 34.0% | Primarily affects younger animals, impairing growth |
| Fasciola species | 21.7% | Liver fluke; more likely in donkeys than mules |
| Oxyuris equi | 17.4% | Causes intense itching and discomfort |
| Mixed Infections | 58.1% | Highlights the burden of co-infection with multiple parasites |
The study also revealed important risk factors. Donkeys were four times more likely to be infected with Fasciola species than mules, and strongyle infections were more than twice as likely in midland agroecology compared to lowland areas 3 .
Another study from Wolaita zone, Southern Ethiopia, revealed a shocking 100% prevalence of strongyle infection in both donkeys and horses, with an average egg count indicating a moderate to severe level of infection .
Addressing the challenge of gastrointestinal helminths in urban working equines requires a multi-pronged approach that moves beyond simply dispensing medication.
The future lies in targeted selective treatment, where only animals showing a high parasite burden (based on fecal egg counts) are treated. This preserves "refugia" – parasites not exposed to the drug – which helps slow the development of resistance 7 .
Simple changes can make a big difference. Regular removal of manure from yards and stables breaks the parasite life cycle. Ensuring animals have good quality feed and clean water helps boost their natural immunity 7 .
Owners are the first line of defense. Educational programs that teach the basics of parasite life cycles, the importance of manure management, and the signs of illness can empower owners to take proactive steps.
| Tool/Reagent | Function | Application in the Field |
|---|---|---|
| Microscopy & Flotation Solution | Concentrates and floats parasite eggs for identification and counting | The cornerstone of fecal analysis for diagnosis and monitoring infection levels |
| McMaster Technique | A quantitative method to determine the number of eggs per gram (EPG) of feces | Provides a measure of infection severity and helps assess the need for treatment |
| Coproculture | Differentiates between various strongyle species by harvesting and identifying their larvae | Essential for understanding the specific parasite population and its potential pathogenicity |
| Benzimidazoles (e.g., Fenbendazole) | A class of anthelmintic drugs that disrupts the energy metabolism of parasites | Widely used for deworming, but resistance is a growing concern 2 7 |
| Macrocyclic Lactones (e.g., Ivermectin) | A broad-spectrum anthelmintic that paralyzes and kills parasites | Highly effective against many internal and external parasites; one of the most common treatments 2 7 |
The health of urban working equines is not just an animal welfare issue; it is a matter of economic stability and social equity for the millions who depend on them. By using science to guide our actions—through better diagnosis, smarter treatment, and improved care—we can lift this hidden burden and ensure these noble animals receive the protection they deserve.