Systematic Veterinary Virology

TRANSMISSION

• The virus is transmitted from direct contact with infected dogs. Indirect transmission, eg, from fecal-contaminated fomites, is also an important source of infection. The virus is shed in the feces of infected dogs for up to 3 wk after infection. Recovered dogs may serve as carriers and shed the virus periodically.
• After ingestion, the virus replicates in lymphoid tissue of the oropharynx; from there, it spreads to the bloodstream. It attacks rapidly dividing cells throughout the body, especially those in the bone marrow, lymphopoietic tissue, and the crypt epithelium of the jejunum and ileum. Replication in the bone marrow and lymphopoietic tissue causes neutropenia and lymphopenia, respectively.
• Replication of the virus in the crypt epithelium of the gut causes collapse of intestinal villi, epithelial necrosis, and hemorrhagic diarrhea. Normal enteric bacteria, eg, Clostridium perfringens and Escherichia coli enter the denuded mucosa leading to secondary bacterial infection