Oropharyngeal avian trichomonosis treatment remains crucial for bird owners and veterinarians dealing with this potentially fatal parasitic disease caused by Trichomonas gallinae. Affecting pigeons, raptors, budgerigars, canaries, finches, and other pet birds, it presents as yellow or white caseous lesions in the oropharynx, often leading to vomiting, lethargy, emaciation, and higher mortality in young birds. While nitroimidazole drugs like metronidazole and dimetridazole have been staples since the 1950s, rising resistance in strains from domestic pigeons and budgerigars underscores the need for updated avian trichomonosis treatment strategies, including novel delivery systems and plant-based alternatives.
Historical Evolution of Avian Trichomonosis Treatment
Early attempts at avian trichomonosis treatment in the 1940s and 1950s involved copper sulfate, hydrochloric acid, Lugol’s solution, and mercuric chloride, which showed some anti-trichomonal effects in naturally infected pigeons but caused poor palatability, prolonged dosing issues, or toxicity. Substances like furazolidone, penicillin, streptomycin, aureomycin, nitrophenide, sulfamides, Osmaron B, and nihydrazone proved minimally effective or toxic at high doses.
Nitrothiazoles marked a breakthrough, starting with enheptin (2-amino-5-nitrothiazole). Tested in pigeons, doses of 18–45 mg/kg/day for 7 days achieved 100% efficacy in natural infections, while 0.125% in drinking water for 6 days yielded 86.7–100% success, though older birds showed lower response. In experimental infections with the pathogenic Jones’ Barn strain, 30 mg/bird/day for 14 days ensured complete elimination.
PRISMA flowchart employed for the systematic review of avian oropharyngeal trichomonosis treatments, failures and alternatives
This systematic review, following PRISMA guidelines, analyzed 60 articles from PubMed, Scopus, and Web of Science up to October 2022, focusing on treatments, resistance, and alternatives for T. gallinae.
Standard Nitroimidazole-Based Avian Trichomonosis Treatments
Metronidazole and dimetridazole, introduced in the 1960s, surpassed enheptin. Doses of 50 mg/kg for 5 days or 0.05–0.1% in drinking water for 3–6 days delivered 100% efficacy in pigeons, though 6-day dimetridazole caused transient ataxia in 11.7% of birds. Combinations like metronidazole with oxytetracycline (40–60 mg/kg, 6 days) achieved 80% success in mildly affected pigeons.
Ornidazole (2.5–5 mg/bird in water for 3 days or 10–40 mg/kg solid for 3 days), carnidazole (10 mg/kg single dose), and ronidazole followed, with drinking water administration preferred despite challenges like flock hierarchy and palatability affecting intake.
| Product | Dose | Success Rate | Side Effects | Type of Infection | Reference |
|---|---|---|---|---|---|
| Enheptin | 18–45 mg/kg/d, 7 d | 100% | None | Natural/Experimental | [14] |
| Metronidazole | 50 mg/kg, 5 d | 100% | None | Natural/Experimental | [15] |
| Dimetridazole | 0.05% DW, 3–6 d | 100% | Ataxia (11.7% at 6 d) | Natural | [15] |
| Carnidazole | 10 mg/kg | 87.5–100% | None | Natural | [24,25] |
| Ornidazole | 10–40 mg/kg, 3 d | Effective | None | Natural | [23] |
DW: drinking water; d: days.
In non-pigeon species, these drugs treated budgerigars (dimetridazole 0.05 mg/g for 7 days; metronidazole 30 mg/kg for 10 days, 40% success), canaries (metronidazole 200 mg/L DW, 5 days), finches, bald eagles (dimetridazole 50 mg/kg, multiple doses), cinereous vultures, falcons, and wood pigeons successfully. Prompt treatment is vital, as severely debilitated or young birds often succumb despite therapy.
Resistance to Nitroimidazoles in Avian Trichomonosis Treatment
Since 1990, resistance to nitroimidazoles has emerged, particularly in frequently treated pigeon flocks and budgerigars. In vivo failures included sequential treatments failing in refractory pigeons and low efficacy (0–19%) with carnidazole/dimetridazole.
In vitro studies confirmed resistance across metronidazole, dimetridazole, ronidazole, carnidazole, ornidazole, and tinidazole, with MICs up to 500 µg/mL. Strains from racing pigeons and budgerigars showed highest resistance, often linked to genotype A. Underdosing via drinking water and frequent prophylaxis likely contribute.
| Strain | Host | MIC Dimetridazole (µg/mL) | MIC Ronidazole | MIC Metronidazole | Reference |
|---|---|---|---|---|---|
| HF26 | Bonelli’s eagle | 7.8 | 1.9 | 7.8 | [38] |
| 1FG | Racing pigeon | 187.5 | 31.2 | 500 | [38] |
| 8855-C6/06 | Racing pigeon | 83.3 | 83.3 | 103.3 | [39] |
Administering drugs with food may enhance contact time in the crop, improving outcomes against resistant strains.
Novel Delivery Systems and New Molecules for Avian Trichomonosis Treatment
Limited studies explore alternatives: chitosan alone (125–1250 µg/mL, >80% mortality in 1–6 h) and carriers like chitosan-cellulose-tannic acid, nanowhiskers, zeolite-tannic acid, zinc oxide, and nanolactoferrin loaded with metronidazole or rhodanine achieved rapid 100% growth inhibition, often outperforming free metronidazole (50 µg/mL). Nanolactoferrin-metronidazole showed no hepatotoxicity in pigeons.
| Compound/Carrier | Concentration | % Growth Inhibition (at 3 h) | Reference |
|---|---|---|---|
| Chitosan | 125–1250 µg/mL | >80–100% | [44] |
| MTZ-Nanolactoferrin | 50 µg/mL | 100% | [48] |
| Poly(rhodanine)-ZnO | 10 mg/mL | 100% | [49] |
Promising Natural Products in Avian Trichomonosis Treatment
Plant extracts offer resistance-bypassing options. Ethanolic extracts of ginger (Zingiber officinale) and lavender (Lavandula angustifolia) (MIC 25–50 µg/mL), essential oils of Dennettia tripetala (0.13% v/v), Artemisia sieberi, Pelargonium roseum, alkaloid extracts of Peganum harmala (MIC 15 µg/mL), and methanolic extracts of Murraya koenigii (IC50 1.9–34 µg/mL) excelled. Lamiaceae oils (e.g., Thymus vulgaris, Salvia sclarea) showed moderate-high activity.
Pure compounds like carbazoles (girinimbine IC50 1.1 µg/mL), furocoumarins (imperatorin 6 µg/mL), carvacrol (0.39 µg/mL), thymol, and linalyl acetate rivaled metronidazole, with low cytotoxicity.
| Plant Extract | IC50/MIC 24 h (µg/mL) | Vs. Metronidazole | Cytotoxicity | Reference |
|---|---|---|---|---|
| Zingiber officinale (EE) | -/25 | -/50 | N.t. | [61] |
| Murraya koenigii (ME, seed) | 1.9/- | 1.9/- | Low | [52] |
| Peganum harmala (AE) | -/15 | -/50 | N.t. | [63] |
| Carvacrol | 0.39/- | 2.17/- | Low | [65] |
In vivo, these matched metronidazole efficacy without notable toxicity.
Conclusion
Avian trichomonosis treatment relies on nitroimidazoles like dimetridazole and metronidazole (50 mg/kg, 5 days), but resistance necessitates alternatives such as plant extracts from Murraya koenigii, ginger, and Lamiaceae, alongside advanced delivery systems. Always administer via monitored drinking water or food, prioritizing early intervention in pet birds like pigeons and budgerigars. Consult an avian veterinarian for tailored protocols and resistance testing to ensure success.
References
[1-65] As detailed in original systematic review (Microorganisms 2022, 10(11), 2297). Key sources: PubMed, Scopus, Web of Science. For full list, see https://doi.org/10.3390/microorganisms10112297.
