Dr. Sathya Sooryan,
MVSc Animal Nutrition, PGDOH
Vetogen Animal Health
Its 10.4£ billion (£7.7–£13.0 billion), global poultry industry pays to coccidiosis every year, equivalent to £0.16/chicken (17.21₹/bird) produced (Blake et.al 2020). Coccidiosis is undeniably a devastating disease for the poultry industry, impacting not only economically but also posing a significant public health concern. This is due to the entry of drugs used for coccidiosis prevention and treatment into the food chain, adding to the list of concerns and causing hesitancy among people in consuming poultry meat. Producers and veterinarians bear the burden of both losses and blame, while also missing out on the opportunity to contribute to a world with sufficient protein.
Coccidiosis-related losses stem from a decrease in production resulting from reduced growth, diminished feed conversion efficiency, higher mortality rates, and the added costs of treatment. Although drug usage commences once visible signs appear, a substantial 70% of losses occur earlier due to subclinical infections resulting from poor feed conversion, compromised health, and decreased productivity (Fisher, 1998).
Why is Coccidiosis Different and Difficult to Control?
Unlike bacterial and viral infections, coccidiosis has unique characteristics that make it different and challenging to control in poultry. One significant difference is the complex life cycle of coccidia. The parasites have multiple stages of development, including oocysts that are shed in the feces of infected birds. These oocysts can survive in the environment for more than a year, leading to widespread contamination and potential reinfection of the flock. Intricate development and transmission dynamics of Eimeria parasites makes it challenging to break the coccidia life cycle Shirley et al. (2005).
Additionally, coccidia possess the ability to produce oocysts with varying levels of resistance to common disinfectants and anticoccidial drugs. This resistance can develop relatively quickly, further complicating control efforts. Vaccination strategies for coccidiosis stimulate immunity against selected Eimeria spp. but they require precise administration protocols and monitoring to avoid overexposure and disease outbreak. Mollenkopf et al. (2019) highlighted frequent and improper use of these drugs has led to reduced efficacy, rendering some treatments less effective over time and significant development of resistance against widely used anticoccidials in broiler flocks, emphasized the necessity for strategic drug rotation and alternative control measures.
Drugs Currently in Practice – MOA, Key Benifits and Limitations
Below is the overview of different class of anitcoccidial drugs currently in practice and their, Mechanism of action, Key Benefits and limitation in controlling coccidiosis in long term
Table 1. Overview on anitcoccidial drugs
|Anticoccidial Class||Examples||Mechanism of Action||Key Benefits||Limitations|
|Ionophores||Monensin||Disrupts ion transport across coccidia’s cell membrane||Effective against multiple Eimeria species||Can cause harm to non-target species, can lead to reduced efficacy due to cross-resistance, and requires withdrawal period before processing birds for consumption|
|Chemicals||Amprolium||Thiamine analog interfering with folic acid metabolism||Safe for use in chickens at recommended doses||Not suitable for long-term use due to the risk of developing resistance|
|Decoquinate||Can be used in combination with other drugs|
|Diclazuril||Inhibits development of coccidia by affecting mitochondria||Safe and effective in reducing oocyst shedding||Resistance may develop over time, not suitable for long-term use|
|Antibiotics||Nicarbazin||Acts on coccidia’s energy metabolism||Effective against different Eimeria species||Limited effectiveness against some strains of Eimeria, can lead to the development of resistance, not suitable for long-term use|
|Synthetic Agents||Toltrazuril||Interferes with coccidia’s mitochondria||Highly effective against coccidiosis||Not suitable for continuous use due to the risk of resistance development|
|Sulfonamides (e.g., Sulfadimethoxine)||Interferes with folic acid synthesis||Used in combination with other drugs for synergy||Resistance may develop with prolonged use, withdrawal period required|
This table is a general overview of common anticoccidials in practice.
Vaccines for Coccidia
Most commercially available anticoccidial vaccines contain live oocysts of attenuated or non-attenuated strains of coccidia (Shirley et al., 2007) but until recently their use was limited to birds reared for egg production. They may be administered in the drinking water or sprayed on the feed at the farm but this is labour intensive and expensive. Recent improved methods of administration, such as spray cabinets in the hatchery, may facilitate their use in broiler chickens but still use of vaccine is not a promising solution for coccidiosis control (Chapman, 2000, Williams, 2002a).
Shuttle Program is commonly used management strategy to control coccidiosis in poultry. It involves alternating the use of different drug (drug rotation)or classes (class alteration) of anticoccidial drugs during different production cycles orin a growth cycle (Shuttle programme). In drug rotation the development of resistanceis slowed down by providing temporary break from using a particular drug.Whereas in class alteration a different class of anticoccidials with different modes of action, affecting different stages of coccidia’s life cycle is used to reduce the chance of resistance development. The primary objective of the shuttle program is to minimize the development of resistance to specific anticoccidials and maintain their efficacy over time.
Limitations of the current cocci controls program and drugs:
The development of resistance in coccidia against various anticoccidial drugs is a rapid and complex process involving target-site mutations, metabolic detoxification, reduced drug uptake, and potentially multiple mechanisms acting together. While different drugs and program is providing an immediate relief from the devastating disease, continuing so will put disastrous ending to sustainable and profitable farming.
In coccidian control programsResistanceis not cessed but postponed. Over time, the coccidia population develop partial resistance to multiple classes of drugs, compromising their overall efficacy. Complexity and Cost of Implementing the shuttle program requires careful planning, record-keeping, and coordination between flocks. It can be challenging and costly to manage multiple drug classes, especially for smaller poultry producers.The shuttle program highlights the need for continuous development of new and effective anticoccidials with different modes of action. However, there have been limited advancements in new drugs for coccidiosis in recent years.
Residues entering in food chain has serious health implications and anticoccidial drugs contribute to the development of antimicrobial resistance (AMR) in both coccidia and potential zoonotic pathogens. These issues resonate with other public health concerns making situations worst for growth to the industry.
Overcoming the challenge of resistance in coccidiosis
Overcoming coccidiosis resistance requires a comprehensive approach including sensitivity testing, vaccination, improved management practices, strict biosecurity measures, and the strategic use of natural anti-coccidials. Regular sensitivity testing helps identify effective drugs against prevailing strains (Shirley et al., 2007). Vaccination stimulates immunity and reduces oocyst shedding (Chapman et al., 2013). Better management practices and hygiene minimize coccidiosis risk (Zhao et al., 2019). Biosecurity measures prevent resistant coccidia spread. Natural anti-coccidials offer effective and immune-enhancing alternatives. Continuous monitoring and research keep control strategies up-to-date.
Don’t Shuttle Do Settle…
Phyto-Molecules are not the Future – its Present:
Natural solutions in coccidiosis requires a nuanced understanding of their mechanisms of action and their potential. Recent studies from various institutes and organization (Table 2) has proven record of effect of different Herbs, phyto-extracts, or phyto-molecules exhibiting the anticoccidial effect with mode of action different, complex and combination of many MOA, which ensures natural extracts to be the most promising compounds of present to overcome all the major concerns and limitation concerned with present control measures.
Below are the affects of Natural Compounds which ensure performance during coccidiosis, and public safety
- Antimicrobial and Antiprotozoal Properties: Many herbs and phyto-extracts possess antimicrobial and antiprotozoal properties, which can help combat coccidial infections. For example, compounds like tannins and saponins found in certain plant extracts have demonstrated inhibitory effects on Eimeria parasites Wunderlich et al. (2014).
- Immune Modulation: Some phyto-molecules have been shown to modulate the immune response in animals, enhancing their ability to combat coccidial infections. These compounds can stimulate the production of cytokines and other immune mediators that activate the host’s immune system to fight off the parasites. Research by Perić et al. (2018) investigated the immunomodulatory effects of specific phyto-extracts against coccidiosis.
- Gut Health Improvement: Certain herbs and phyto-extracts have been reported to improve gut health and integrity, which is crucial for protecting against coccidial infections. These compounds can strengthen the intestinal barrier, reducing the attachment and invasion of Eimeria parasites. A study by Ziaran et al. (2016) explored the effect of selected plant extracts on gut health and coccidiosis in broiler chickens.
- Antioxidant Activity: Oxidative stress plays a role in coccidiosis pathogenesis. Some phyto-molecules act as antioxidants, scavenging free radicals and reducing oxidative damage caused by coccidial infections. Research by Qaisrani et al. (2019) investigated the antioxidant potential of certain herbs in broiler chickens challenged with Eimeria tenella.
- Public Health Safe and Sustainability: Incorporating natural compounds in coccidiosis control has no residual and withdrawal and is complete safe.such as reduced environmental impact and improved sustainability compared to chemical agents. These compounds often have lower toxicity and are biodegradable, minimizing their adverse effects on the environment.
Phyto-extracts, or phyto-molecules as Anticoccidials
Below is the list of few promisingphyto-active compounds along with their mechanism of action, key benefits, and limitations.
|Active Ingredient||Mechanism of Action||How It Kills Protozoa||Key Benefits||References|
|Curcumin||Antiprotozoal, antioxidant, and anti-inflammatory||Inhibits protozoal development and replication||– Reduces oocyst shedding – Supports immune response||Rajput et al. (2013); Zhao et al. (2017)|
|Oregano Oil||Antimicrobial, antiprotozoal, and antioxidant||Disrupts protozoal cell membrane and metabolism||– Reduces coccidial infection – Supports gut health||Wunderlich et al. (2016); Khan et al. (2020)|
|Garlic Extract||Antimicrobial, immunomodulatory||Interferes with protozoal enzyme systems||– Supports immune response – Reduces oocyst shedding||El-Saadony et al. (2020); Ibrahim et al. (2020)|
|QuillajaSaponins||Antiprotozoal, immunomodulatory||Disrupts protozoal cell membrane and metabolism||– Reduces oocyst shedding – Supports gut health||Suarez-Martinez et al. (2014); Crespo et al. (2016)|
|Berberine||Antiprotozoal, anti-inflammatory||Inhibits protozoal DNA synthesis||– Reduces coccidial infection – Supports gut health||Zhang et al. (2016); Dkhil et al. (2019)|
|Cinnamon Extract||Antiprotozoal, immunomodulatory||Disrupts protozoal cell membrane and metabolism||– Supports immune response – Reduces oocyst shedding||Gad et al. (2016); Hegazy et al. (2019)|
|Grape Seed Extract||Antioxidant, immunomodulatory||Supports immune response and reduces oxidative stress||– Supports immune response – Reduces oxidative stress||Guan et al. (2016); Alnaimy et al. (2017)|
|Aloe Vera||Immunomodulatory, anti-inflammatory||Modulates immune response and reduces gut inflammation||– Supports immune response – Reduces gut inflammation||Zhang et al. (2018); Adeyemo|
Natural solutions unlike synthetic drugs not just kills or stops the growth of coccidia, but also ensure gut integrity, immunity, metabolisum, antioxidant capacity and overall performance of the bird with zero residual effect ensuring public safety. Whereas drug rotation, class rotation, shuttle program may give indications of immediate control, emphasis on bouncing back to production and drug resistance concern are clearly overlooked. Natural compound settles all limitation of shuttle program. When the foundation of sustaining livestock farming lies solely in the principles of sustainable farming practices, visionary farmers—both present and future should inevitably choose not to shuttle, but to confidently settle.