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Updated: Jul 13, 2026
A Non-Coding Small RNA MicC Contributes to Virulence in Outer Membrane Proteins in Salmonella Enteritidis
Published on: January 27, 2021
Colonization and organ invasion in chicks experimentally infected with Dermanyssus gallinae contaminated by
Claire Valiente Moro1, Philippe Fravalo, Michel Amelot
1UMR 958 ENVL/INRA Protozoaires Entéricoles et Parasites des Volailles, Ecole Nationale Vétérinaire de Lyon, Marcy l'Etoile, France. valienteclaire@yahoo.fr
Abstract:
The poultry red mite (Dermanyssus gallinae) is the most important and common ectoparasite of laying hens in Europe. This haematophagous mite has been experimentally demonstrated to be a vector of Salmonella Enteritidis by acquiring bacteria through the blood meal or cuticular contact. We have evaluated another route of infection by orally inoculating chicks with mites previously infected by S. Enteritidis. Two methods of infecting the mites were tested: mites contaminated by cuticular contact or during the blood meal. After the washing of mites with paraformaldehyde, groups of 10 Salmonella-contaminated mites were inoculated individually into 1-day-old chicks. The titre of the inoculum suspension was evaluated by crushing mites and followed by bacteriological counting. It was 3x10(4) colony-forming units/chick and 2.7x10(6) colony-forming units/chick, respectively, for cuticular contact and orally mediated contamination of mites. Each bird was found to be positive 12 days post-inoculation. Salmonella colonized the intestinal tracts and invaded the livers and spleens. The caecal content concentration reached a mean level of S. Enteritidis of 8.5x10(4) most probable number (MPN) Salmonella/g. This experiment demonstrated the ability of mites to orally infect 1-day-old chicks with subsequent colonization and multiplication of Salmonella. Consequently, mites infected by S. Enteritidis constitute potential reservoir hosts of this bacterium, allowing it to persist in the poultry house as a source of infection for newly introduced animals. If contaminated mites are found in poultry facilities, effective red mite control should be performed before new batches are introduced into the facility.
Insights
Poultry red mites (Dermanyssus gallinae) can orally infect chicks with Salmonella Enteritidis. These mites act as reservoirs, spreading Salmonella within poultry houses and posing a risk to new flocks.
Area of Science:
- Veterinary Entomology
- Avian Pathology
- Food Safety
Background:
- The poultry red mite (Dermanyssus gallinae) is a significant ectoparasite affecting laying hens in Europe.
- This mite is a known vector of Salmonella Enteritidis, acquiring bacteria via blood meals or direct contact.
Purpose of the Study:
- To investigate the potential for Dermanyssus gallinae to transmit Salmonella Enteritidis to one-day-old chicks through oral inoculation.
- To evaluate Salmonella Enteritidis colonization and systemic invasion in chicks following mite-mediated oral infection.
Main Methods:
- Chicks were orally inoculated with Salmonella Enteritidis-infected mites, contaminated via cuticular contact or blood meal.
- Bacteriological counts determined Salmonella titres in mites and quantified infection levels in chicks' ceca, livers, and spleens post-inoculation.
Main Results:
- Oral inoculation with contaminated mites led to Salmonella Enteritidis infection in all chicks within 12 days.
- Salmonella colonized the intestinal tract and invaded the liver and spleen, with high concentrations in cecal content.
Conclusions:
- Dermanyssus gallinae can serve as a vector for orally transmitting Salmonella Enteritidis to young chicks.
- Contaminated mites act as reservoirs, potentially perpetuating Salmonella infections in poultry houses, necessitating effective mite control before introducing new birds.
