Infection

"Infection" - what is it, definition of the term

«Infection» denotes the penetration of pathogenic microorganisms—bacteria, viruses, fungi, or parasites—into the body of a host organism, followed by replication that disrupts normal tissue function and triggers an immune response. In rodents such as rats and mice, this process often originates from exposure to contaminated environments, vectors, or conspecifics, leading to clinical manifestations that may serve as reservoirs for zoonotic transmission.

Detailed information

Rodents such as rats and mice serve as frequent reservoirs for a variety of pathogenic agents that can compromise health and affect research outcomes. The presence of disease‑causing microorganisms in these species results from exposure to contaminated environments, vectors, or infected conspecifics.

Common pathogenic categories include:

• Bacterial agents: Salmonella spp., Leptospira interrogans, Streptobacillus moniliformis.
• Viral agents: Hantavirus, Rat coronavirus, Mousepox virus (Ectromelia).
• Parasitic agents: Toxoplasma gondii, Heligmosomoides polygyrus, Mycobacterium avium complex.
• Fungal agents: Candida albicans, Aspergillus spp.

Transmission pathways are diverse:

1. Direct contact with contaminated bedding or feces.
2. Inhalation of aerosolized particles carrying pathogens.
3. Ingestion of contaminated food or water.
4. Vector‑mediated transfer via ectoparasites such as mites and fleas.
5. Vertical transmission from dam to offspring during gestation or lactation.

Clinical manifestations vary with the etiologic agent but often include weight loss, lethargy, ruffled fur, respiratory distress, gastrointestinal disturbances, and abnormal behavior. Subclinical infections may persist, influencing experimental variables without overt signs.

Diagnostic approaches comprise:

• Culture and sensitivity testing of tissue samples.
• Polymerase chain reaction (PCR) assays targeting specific genetic markers.
• Serological screening for antibody titers.
• Histopathological examination of organ sections.
• Radiographic imaging for pulmonary involvement.

Control strategies focus on biosecurity, environmental management, and therapeutic intervention. Key measures involve:

• Strict quarantine of incoming animals and regular health monitoring.
• Routine sanitation of cages, feed, and water systems.
• Use of barrier facilities to prevent vector entry.
• Administration of appropriate antimicrobial or antiparasitic agents based on susceptibility profiles.
• Implementation of vaccination programs where available.

Effective management of disease processes in rat and mouse colonies safeguards animal welfare, ensures reproducibility of scientific data, and reduces zoonotic risk to personnel.