What disease can cause fatal respiratory disease in newborn and weanling mice?

• A. Minute virus of mice
• B. Sendai virus
• C. Mouse norovirus
• D. Helicobacter spp.

Answer: (B)

Young mice are especially vulnerable to respiratory viral infections, and Sendai virus is the classic cause of fatal pneumonia in newborn and weanling mice. This virus, a murine parainfluenza type 1 agent, invades the respiratory epithelium and triggers necrotizing bronchiolitis and interstitial pneumonia. In newborns and weanlings the infection often progresses rapidly, producing signs such as rapid or labored breathing and nasal discharge, and can lead to death. Older mice may only show mild or subclinical disease, so the dramatic fatal respiratory illness is most evident in the youngest age groups. Because it spreads readily through aerosols and direct contact, outbreaks can devastate a breeding colony, making strict quarantine and colony management essential for control.

Minute virus of mice tends to cause systemic disease in neonates, including thymic atrophy and growth issues, rather than a primary fatal respiratory illness. Mouse norovirus mainly causes gastroenteritis with diarrhea and weight loss, not acute fatal respiratory disease. Helicobacter spp. colonize the stomach and cause gastric inflammation, not respiratory failure.