Lec - Bacteria and Bacterial Diseases of WLDF

Bacteria

exist almost everywhere

contain a rigid cell well, cell membrane, cytoplasm, single double-stranded circular loop of DNA, flagella, pili, and ribosomes (only organelles)

lack nuclei

reproduce by binary fission

Bacterial Shapes and Arrangement

Cocci (singles, pairs, clusters, chains)

Rods (bacilli, pairs, chains, coccobacilli)

Spirals (incl. spirochetes)

Pleomorphic

Gram Positive Bacteria

have a thick peptidoglycan layer that absorbs violet stain and retains it during “destaining”

violet masks the pink counterstain

Gram Negative Bacteria

have a lipopolysaccharidae outer membrane, don’t retain the violet stain, and are counterstained pink by saffranin

Mycoplasma spp.

lacks a cell wall, smallest bacteria, intra/extracellular

several species cause disease in birds and other vertebrates

unapparent infections to acutely severe disease and chronic carriers are common

Songbirds: upper-respiratory signs include - nasal discharge, conjunctivitis, decreased weight gain, death

Avian Cholera (Pasteurella multocida - in birds)

directly transmitted (+ no IH)

transmission is density-dependent and the largest outbreaks occur during winter on the staging areas

acute death (6-12 hrs; 1-2 days common) caused by toxin

lots of strains; all diff w/ some affecting either birds, mammals, or both

Mgmt - hazing to decrease densities, carcass removal, refuge management to separate snow geese from other susceptible species

Transmission of Pasteurella multocida among birds

many ways to transmit, ingestion > aerosols > direct contact

Bird to bird contact (transmission of Pasteurella

multocida)

secretions from infected birds shedding P. multocida

requires close contact

Ingestion (transmission of Pasteurella

multocida)

most common route of transmission

consumption of diseased carcasses by scavengers and predators

ingestion of P. multocida in food and water from contaminated environments

Aerosols (transmission of Pasteurella

multocida)

may be important in heavily contaminated environments, such as during major die-offs

activities that result in splashing of surface waters result in bacteria-laden sprats when water becomes contaminated

Bacterial Pneumonia (+/- Septicemia) in ungulates

most cases have little or no impact on wildlife population dynamics

epidemics of pneumonic or septicemic pasteurellosis can cause significant mortality in susceptible species

domestic sheep are chronic carriers of P. multocida, M. haemolytica and Mycoplasma ovipneumoniae that only develop disease occasionally

contact between bighorn and domestic sheep increases risks of bighorn die-offs

bighorn sheep may harbor these bacteria and may suffer severe disease with significant population declines

Bacterial Pneumonia in Ruminants

Gram negative bacteria that infect most species of wildlife (many spp. w/ dif diseases)

infections of respiratory tracts and other organs

respiratory signs = bronchopneumonia, interstitial pneumonia, pleuritis, purulent discharge from the nose and mouth, coughing, fever, toxic shock, and death

toxic shock

lipopolysaccharide toxin that compromises macrophages and other leucocytes

Brucellosis (Brucella abortus)

transmission = direct contact, bodily fluids, ingestion of milk or meat, licking aborted tissues

bison = abortion, w/ retained placenta, fever, infertility, etc.

elk = abortion, no retained placenta

moose = weakness, debilitated, fever, etc

predators = non-diseased carriers (coyotes, bears, birds)

zoonosis + risk to livestock

Brucellosis in bison

current mgmt: haze the bison back into the park, capture and test those not hazed, slaughter those that test positive and send meat to tribes, shoot those that can’t be hazed back or herded into facilities for testing

federal agencies currently spend at least 2.4 million dollars/ yr to implement the plan

Tuberculosis (Mycobacterium bovis)

bacteria causes TB in most mammals and some birds

Other strains:

M. tuberculosis - is the number one cause of TB in humans

M. avium - avian tuberculosis and Johne’s disease of ungulates

M. leprae - leprosy (non-TB)

Signs of Bovine TB

most infected animals appear healthy, signs may not be noticed, chronic, progressive, disease

signs commonly include fever, chronic, progressive, emaciation, dyspnea, swollen lymph nodes

tuberculous lesions appear yellow caseous/necrotic areas in greyish fibrous nodules

no practical treatment

Animal to Animal Transmission of TB

disease transmitted from infected animals by aerosols (coughing), ingestion, and environmental contamination with feces and urine or via bite wounds

density-dependent transmission

bacilli survive in the environment for days to many months especially in cool weather

Tuberculosis in White-tailed Deer

Michigan, Minnesota, and Manitoba

Management: wildlife disease surveys and deer management to minimize risks of human infections, cull infected animals, carcass and meat inspection, proper food handling

TB in Badgers in the UK

badgers transmit M. bovis bacilli by respiratory droplets, urine, and bites to other badgers, and probably via urine to cattle via environmental contamination

infected large portions of cattle herds, major culling projects that were VERY expensive

new vaccine licensed