Bacteria and Parasite Infections in Animals

Bacteria pathogenicity

Bacteria cause diseases by damaging host cells and stimulating host inflammatory/immune response; ability to cause diseases depends on number of organisms, immune status, and virulence factors

Bacteria immune evasion

Some toxins in bacteria can kill phagocytes, synthesize protein to prevent opsonization, or have a capsule to prevent detection

Bacteria vs phagosome

Some bacteria have a mechanism to prevent phagosome maturation (prevent function of NADPH, removing the necessary energy for maturation)

Salmonella

Bacterial zoonotic infection in poultry; can survive in water for 4-6 weeks, 2-4 months in meat, and years in frozen meat; can be killed in 5min, 70C

Salmonella symptoms

Decreased appetite, depression, ruffled feathers, weight loss, and watery-mucoid diarrhea

Salmonella post-mortem lesions

Swollen, friable liver, necrotic foci, enlarged spleen/kidney, anemia, and enteritis

Parasite infection

Infections caused by parasitic tissue invasion/destruction; toxin production, immune response invasion/manipulation, and nutrition depletion results

Coccidiosis

Parasitic infection in poultry; oral from ingestion of infective sporulated oocysts from a contaminated environment, young birds (~3 weeks)

Coccidiosis symptoms

Depression, ruffled feathers, enteritis, and bloody diarrhea

Coccidiosis post-mortem lesions

White plaques and hemorrhages in the intestinal tract and bloody intestinal content

Vaccination unavailability

Vaccines for parasites are often unsuccessful in comparison to use for viruses and bacteria because of their large/complex nature, diverse gene expression at different stages, and requirement for cellular immunity over vaccines