Inf. diseases II - Ruminant respiratory disease 2/2 Flashcards
Bovine viral diarrhea (BVD) ) is a highly contagious disease of cattle, caused by a Pestivirus, and characterized by (3)
variable diarrhea,
respiratory illness and
persistently infected (PI) calves.
Causative agent of BVD.
genus, family, DNA type
Bovine viral diarrhea virus (BVDV)
Genus Pestivirus,
family Flaviviridae
RNA virus
Biotypes/strains of BVDV.
Bovine viral diarrhea virus
Biotypes 1 and 2
- 1 – worldwide
- 2 – North America and occasionally Europe
Both biotypes have non-cytopathic and cytopathic forms.
Non-cytopathic (NCP) form is most common.
Variable clinical disease with enteritis and respiratory illness .
Causes persistently infected (PI) animals after intrauterine transmission.
Cytopathic (CP) form causes mucosal disease in persistently infected PI animals.
Causes cytopathic effect in cell culture
Both BVDV biotypes have non-cytopathic and cytopathic forms.
Describe the non-cytopathic (NCP) form.
Non-cytopathic (NCP) form is most common.
Variable clinical disease with enteritis and respiratory illness .
Causes persistently infected (PI) animals after intrauterine transmission.
Both BVDV biotypes have non-cytopathic and cytopathic forms.
Describe the cytopathic (CP) form.
Cytopathic (CP) form causes mucosal disease in persistently infected PI animals (those who get infected in utero?).
Causes cytopathic effect in cell culture.
What all types of disease can BVDV cause? (6)
benign bovine virus diarrhea,
mucosal disease,
peracute fatal diarrhea,
thrombocytopenia and hemorrhagic disease,
reproductive failure,
congenital abnormalities in calves.
Host range of BVDV.
ruminants, especially cattle
Found worldwide.
(NOT in humans but this is a notifiable dz nonetheless)
Morbidity of BVDV.
Morbidity 40%
Mucosal disease: <5%
Mortality of BVDV.
Mortality 20%
Excretion of BVDV.
Excretion: nasal discharge, saliva, semen, feces, urine, tears and milk, aborted fetuses
Major source of virus: PI animals!!!
Transmission mode and route of entry of BVDV.
Direct contact
Transplacental transmission
Indirect transmission: fomites, flies and airborne
Route: oral, respiratory, genital, transplacental
Clinical signs of BVDV.
Can result in a wide spectrum of clinical dz varying from subclinical infection (70-90%) to fatal dz.
Most common signs:
Infertility or abortion
Diarrhea
Mucosal disease
Respiratory signs
How does the fatal hemorrhagic disease form of BVDV develop?
Immunocompetent adult animals can experience transient infection, but if the animal happens to be pregnant before day 120 of gestation, the fetus will be become persistently infected (if it doesn’t abort).
Only the ncp biotype can cause persistent infection of the bovine fetus.
Initially the fetus is infected with the non-cytopathic biotype, this can mutate and become cytopathic and eventually cause fatal hemorrhagic mucosal disease. Typically die before 2 years old.
There are two different strains of BVD: Transient type 1 and type 2.
Both strains can have the same effect on fertility and overall health, however type 2 can be more severe and can result in bleeding syndrome and death.
Describe differences in the symptoms of each type.
Infection with BVDV from approximately nine days prior to service until 120 days of gestation may result in: (4)
Failure to conceive
Early embryonic death
Fetal loss
Persistently infected (PI) calves
Clinical signs of mucosal disease BVDV.
Fever
Diarrhea
Inappetence
Progressive emaciation
Rough dry hair coat
Chronic bloat
Hoof deformities
Chronic erosions in the oral cavity and on the skin
IP of BVDV mucosal disease.
IP animals 6-24 months of age
Morbidity of BVDV.
Morbidity 44%
Mortality of BVDV.
mortality <100%
Post mortem signs of mucosal disease BVDV.
lesions in alimentary tract
Erosions
Lesions on Peyer’s patches
Pneumonia (mostly secondary)
If you test a cow’s blood and its positive for BVDV virus but negative for antibodies against BVDV - what is it?
a persistently infected individual
then if its virus mutates or it happens to catch the other strain (cytopathic), it develops fatal mucosal disease.
Tx for BVDV.
no tx
Prevention & control of BVDV. (3)
Control:
Detection and elimination of PI animals from the herd
Prevention of introduction of infection into herd
Vaccination of breeding females to prevent fetal infection
Eradication of BVDV by
detection and elimination of persistently-infected animals (in this case, you can’t have used vax (in order for you to be able to identify them)) and strict biosecurity measures to prevent introduction of PI animals into the herd.
Mycoplasma bovis infection is a contagious disease of cattle, characterized by (4)
respiratory disease,
mastitis,
arthritis and
otitis media.
Causative agent of mycoplasma bovis infection.
Genus, family, type etc.
Genus Mycoplasma,
family Mycoplasmataceae
Has no cell wall
The most pathogenic bovine mycoplasma is in Europe and North America.
Survival of mycoplasma bovis in environment.
Survival in water 4°C for 2 weeks.
Susceptible to desiccation and sunlight.
Host range for mycoplasma bovis infection.
mainly cattle
Has been isolated also from poultry, small ruminants, humans.
The presence of M. bovis does not always
result in dz
In Europe ?% of calf pneumonias are due M. bovis.
In Europe 25-35% of calf pneumonias are due M. bovis.
Excretion of mycoplasma bovis.
Excretion:
respiratory secretions, milk, ocular discharge, urogenital tract.
Shedding for few months; or intermittently for months or years.
Stressful events increase nasal shedding rates.
Transmission mode & route of entry for mycoplasma bovis.
Direct contact
Fomites (at milking – udder-to-udder; feed, water)
Ingestion (calves)
Route: respiratory, alimentary, intramammary
Clinical signs of mycoplasma bovis mastitis.
Many infections are subclinical.
Non-specific signs:
More than one affected quarter
Drastic decrease in milk production
Mild signs of systemic illness
Mammary gland might be swollen (not painful)
Mammary secretions vary from mildly abnormal to gritty or purulent; sometimes brownish.
Clinical dz can persist for weeks.
Return to production is possible but slow.
Clinical signs of mycoplasma bovis pneumonia.
Non-specific signs:
fever, tachypnea, dyspnea, decreased appetite; with or without nasal discharge and coughing.
In chronic cases: poor weight gain
4 “forms” of mycoplasma bovis infection
penumonia
mastitis,
arthritis and
otitis media.
Post mortem signs of mycoplasmal pneumonia.
Pneumonia:
multiple necrotic foci in lungs filled with dry yellow to white caseous material.
Diameter from few mm to several cm
Extensive fibrosis
Lab analyses for diagnosis of mycoplasma bovis. (3)
Culture – growth often apparent by 48h.
7-10 days incubation is recommended before samples are called negative.
Sensitivity is quite low.
PCR
Serology (ELISA)
Tx of mycoplasma bovis.
With mastitis Tx is not recommended.
Resistance to β-lactam antimicrobials.
No vaccine available in Europe.
Prevention & control of mycoplasma bovis.
No vaccine available in Europe.
Maintain closed herd.
Screen and quarantine purchased animals.
Good animal husbandry and biosafety
Clinical signs of mycoplasma bovis arthritis.
Sporadic – tends to be concurrent with cases of pneumonia or mastitis.
Signs of typical septic arthritis:
acute non-weight bearing lameness with joint swelling, pain and heat on palpation.
Might be febrile and anorexic.
Large rotator joints are commonly affected.
Poor response to treatment.
Clinical signs of mycoplasma bovis otitis media.
Clinical signs due to ear pain and cranial nerve VII deficits.
Ear droop
Head shaking, scratching or rubbing ears
Unilateral or bilateral
Concurrent case of pneumonia, arthritis, or both are common.
Mycoplasma bovis tends to cause one of the following:
pneumonia
mastitis
arthritis
otitis media
However, some other diseases it can cause include: (5)
keratoconjunctivitis,
meningitis,
decubital abscesses,
cardiac disease,
genital disorders.
3 alt. names for malignant catarrhal fever (MCF)
Malignant Head Catarrh,
Gangrenous Coryza,
Snotsiekte
malignant catarrhal fever (MCF) is a noncontagious disease of cattle, caused by Herpesvirus, and characterized by (3)
bilateral corneal opacity,
erosions in oral cavity and
neurological signs.
Causative agent of MCF.
genus, family, DNA type
Malignant catarrhal fever
several Herpesviruses
Genus Rhadinovirus,
family Herpesviridae
DNA viruses
Viruses:
Alcelaphine herpesvirus-1 (AHV-1)
Ovine herpesvirus-2 (OHV-2)
Alcelaphine herpesvirus-2 (AHV-2)
Caprine herpesvirus-2 (CpHV-2)
MCF is caused by multiple viruses belonging to the same family.
What are the viruses? (4)
Alcelaphine herpesvirus-1 (AHV-1)
Alcelaphine herpesvirus-2 (AHV-2)
Ovine herpesvirus-2 (OHV-2)
Caprine herpesvirus-2 (CpHV-2)
Host range of MCF.
Host range: cattle, small ruminants, giraffes
Small ruminants are the reservoir – they do not get sick.
MCF infectious or contagious?
NOT contagious!
yes, is infectious.
The source of transmission for cattle are the sheep.
Clinical disease in cattle that are kept with sheep.
What type of MCF is found in africa?
And what type worldwide otherwise?
(alcelaphine) AHV-1 mostly in Africa,
OvineHV-2 worldwide.
Reported in Estonia sporadically
Morbidity of MCF.
Morbidity 15-100%
Mortality of MCF.
Mortality 90-100%
Transmission of ovine herpes virus-2.
Excretion: nasal discharge, sperm
Intermittently shed with nasal secretions, particularly 6-9 month-old lambs.
Direct contact
Aerogenic – aerosols
Rarely: transplacentally or via colostrum or milk.
Route: respiratory
IP: of MCF
IP: 7 days to 4 months
Clinical signs of MCF:
Initial clinical signs:
Depression, diarrhea, disseminated intravascular coagulation (DIC), dyspnea, high fever, inappetence.
Sudden death
Four forms of MCF.
Peracute form – sudden death
Head and eye form – majority of cattle cases
Intestinal form – initially like head and eye form, but death occurs from severe diarrhea.
Mild form – inoculated animals; recovery expected.
The majority of cattle MCF cases are what form?
Head and eye form
Early stages of the head and eye form of MCF include: (5)
Reddened eyelids
Bilateral corneal opacity
Crusty muzzle, nares
Nasal discharge
Salivation
Later stages of the head and eye form of MCF include:
Erosions on the tongue
Erosions on the buccal mucosa
Clinical signs of MCF in bovine.
Joints, superficial lymph nodes swell
Horn, hoof coverings slough
Nervous signs
Incoordination, head pressing, nystagmus, hyperesthesia
Post mortem signs of MCF.
Erosions on the tongue, soft and hard palate.
Necrotic areas in the omasal epithelium.
Multiple erosions of intestinal epithelium.
Greatly enlarged lymph nodes
Necrotic areas in the larynx. Diphtheritic membrane often present.
Urinary bladder mucosa hyperemic and edematous.
Kidney often has raised white foci on the cortex.
Material for diagnosis of MCF.
Blood
Spleen, lung, LNs, adrenal glands
Lab analyses for diagnosis of MCF. (4)
Histopathology
PCR
Virus isolation (AHV-1)
Serology
AHV-1 antibodies in wildebeest
OHV-2 antibodies in sheep
Tx of MCF.
no specific Tx
ABs and fluids – can be tried on very valuable animals.
Mortality in clinically ill animals <100%.
Prevention and control of MCF.
Prevention: do not keep cattle and sheep together. Separate susceptible species
No vaccine available
