lesson 87 common viral disease

Bovine respiratory disease complex (BRDC)-shipping fever pnuemonia

most common and costly disease in beef industry. high morbidity

multifactorial causes: stress, immunosuppression, viral infection→ secondary bacterial infection

signs: reduced movement, abnormal behavior, reduced feed intake, increased temperature

advanced signs: purulent discharge, cough, rapid respiration, anorexia, fever, and general malaise

Diagnosis BRDC

culture, PCR

sample from deep nasopharyngeal or transtracheal swab

how to handle BRDC cases

test and isolate

treat with ABX and smoetimes NSAIDS for fever

Prevention and control BRDC

vaccinate preshipment, mimize stress, identify sick early and treat

vaccinate

bovine corona virus (BCov)

age dependent syndroms

calf: neonatal yellow tan feces/ diarrhea, dehydration

winter dysentry(adults): acute dark hemorrhagic diarrhea and milk drop

Calf Rotaviral diarrhea

neonatal calves . high morbidity

signs: yellow-green feces/diarrhea, dehydration, weakness

transmission: fecal oral

diagnosis cal rotaviral diarrhea

PCR, ELISA

how are calf rotaviral diarrhea handeled

test and treat-supportive care and abx only for co infection

prevention: colostrum management, biosecurity, age segregation, precalving dam vaccinationen

enzootic bovine luekosis (EBL) aka bovine leukemia virus

mainly subclinical, internal lymphoid tumors, hemolyphatic systemic disease

high prevelance, not highly contagious

causes moderate trade effect, reduced milk production, higher cullign ratediagn

transmission: prolonged direct contact

diagnosis of enzootic bovine leukosis(EBL)

ELISA

test and isolate

no current vaccines

Foot and mouth disease

virus: Picornaviridae. naked RNA. Multiple serotypes so hard to vaccinate.

-high morbidity, low mortality

-slow recovery from disease = economic loss

Notifiable. zoonotic

ruminants and swine

signs: vesicular mucosal lesions→ ulcers, fever, anorexia, reduced milk production, mastitis, abortion

calves<6 months can develop myocarditis→ death

foot and mouth disease in swine

first clinical sign is lameness

-secondary infection common can lose claw

-lesions on snoutp

pathogenesis foot and mouth disease

transmission: inhalation droplets (long distance airborne), infected food, contaminated vaccine, semen, fomites

-virus replicates in pharynxs. incubation is 2-8 days but shedding is 24 hours before onset of symptoms. highly concentration in body fluids

-virus persists for 2 years in cattle and 6 months in sheep after recovery BUT not persistent in swine

-immunity shortlive since there is not imunity to all the serotypes

how is FMD disease handeled

URGENT testing and cull sick and exposed animals→ immediate quarantine of primary and secondary perimeter, restrict human movement (large area drawn b/c airbone and consider wind)

-virus prefers low temperature and high humidity

-prohibition of imports

-burn the carcasses

diagnosis of FMD

antigen ELISA or PCR since more urgent

antibody ELISA available but used for surveillance

Ovine progressive pneumonia (OPP)-Maedi-Visna

maedi-dyspnea, visni-wasting

adult sheep> 2yrs old

slow and progressive disease. long incubation time

signs: progressive weight loss, exercise intolerance, dyspnea, afebrile (no fever), lifelong infection once acquired, hard bag mastitis, neuro signs, abortion

transmission: colostrum and respiratory secretion

diagnosis and control of OPP/ Maedi Visna

flock screening serology (ELISA) confirm with PCR/histo

NO treatment or vaccine

test and cullOvin

ovine pulmonary adenocarcinoma (OPA)/ Jaagsiekte sheep retrovirus (JSRV)

sheep

infectious neoplasia of the lung

signs: progressive dyspnea, weight loss, clear frothy nasal fluid, afebrileDi

diagnosis of OPA/JSRV

wheelbarrow test LF> nasal discharge

ultrasound

NO serology

PCR/ histo

necropsy: pea sized nodules on lungsc

control of OPA/JSRV

test and cull

no treatment or vaccine

Caprine Arthritis Encephalitis (CAE)

enveloped retrovirus,

small ruminants

signs:chronic arthritis, restricted movements, flexion contracture, encephalitis, focal malacia in white matter, mastitis “hard udder”, sometimes resp signs

transmission: high prevelance, colostrum/milk

control of caprine arthritis encephalitis (CAE)

remove neonate from doe during birth provide colostrum, raise in isolation away from infected animals

no vaccine or treatment

diagnosis: antibody detection

external biosecurity

keep disease out of herd

internal biosecurity

prevent disease within herd from spreading to others

quarantine

keep newly acquired animals way from healthy ones

isolation

separate animal with confirmed disease away from the rest

orgnaization that receives monthly reports for endemic diseases

WOAH-world organization for animal health

case

operational definition of a disease for study purpose

3 criterias: clinical signs, immunologic response, lab detection of agent

epidemic curve

display of onset of illness among cases associated with the outbreak