Neonatal diarrhoea

Rota and coronaviruses

October 6, 2010

Viral causes of diarrhoea in neonates

• Rotavirus

• Coronavirus

• BVD

• Bredavirus

• Calicivirus

• Parvovirus

• Astrovirus

Susceptibility of neonates

• Rotaviruses 4 to 14 days

• Coronavirus 4 to 30

0 4 days

ColostralAntibodies in gut

Susceptible period

Prevention of viral diarrhea in calves

• Vaccination of pregnant animals

• Colostrum for 2 weeks

• Management

vaccines against calf diarrhoea

Rotaviruses

Viruses with ds RNA genomes

Reoviridae

Birnaviridae

rotaviruses

bluetongue virus

african horse sickness

infectious bursal disease (chickens)

infectious pancreatic necrosis (salmonid fish)

Rotaviruses

• 7 groups and many serotypes

• DS, segmented genome

• Unenveloped

• Inactivated by phenolic disinfectants

• Relatively insensitive to chlorination

• Persistence?

Rotavirus structure, serogroups and serotypes

VP4

VP7VP6

VP3

VP2

VP1

7 Groups(A->G)

14 serotypes(G)

12 serotypes(P)

Segmented genomes of rotaviruses

implicationselectropherotyping

Bovine rotaviruses

Group A > B>C

Most Group A, serotypes G6 and G10

Pathogenesislactase

water

water

Undigested milk

Shortened and fusedvilli

http://www.bovilis.com/diseases/ncd/pathogenesis.asp

Maintenance of rotaviruses in populations

• stable in environment

• mucosal antibody more important than systemic antibody

• persistence and periodic shedding

Diagnosis

• Detection of virus in fecal smears by FAT– FAT for GrA (PDS)

• feces, $22 includes coronavirus

• jejunum, ileum, $38.50, includes coronavirus

• EM and immune EM• antigen capture ELISAs (human test for Gr A

rotaviruses)– 80 to 95% sensitivity and specificity compared to RT-

PCR (Maes et al. 2003, J. clin micro 41:290)

Coronaviruses

Viruses with +ve RNA genomesPicornaviridae

Caliciviridae

Coronaviridae

Arteriviridae

Flaviviridae

Togaviridae

foot and mouth disease virus

porcine enteroviruses

feline calicivirus

equine arterivirus

pestiviruses (BVD)

coronaviruses

equine encephalitis viruses

Coronaviruses

• SS +ve RNA

• Enveloped

• Epithelial cells of gut and respiratory tract

• Persistent infections

• Increased shedding in winter and at calving (bovine corona virus)

Diagnosis

• FAT on fecal or gut samples ($22.50-38.50/sample)

• EM ($45/sample)

Some other coronaviruses

• Transmissible gastroenteritis and respiratory disease in pigs

• Infectious bronchitis in poultry

• Feline enteric coronavirus (FEC) and infectious peritonitis (FIP)

• Ferret (catarrhal enteritis and FIP-like)

• SARS coronavirus

feline infectious peritonitis

M.C. Horzinek and H. LutzAn update on FIP

Veterinary Sience TomorrowJan, 2001

www.vetscite.org

FIP

• fatal disease of young (3-18 mo), or very old in multi-cat houses or catteries

• not seen before 1950– new virus?– old virus, new disease

• systemic antibodies not protective, may even be harmful

feline enteric coronavirus

• closely related to dog, pig (TGE), human coronaviruses– species specific but K9CV can infect cats

• two serotypes– serotype I

– more common, 70-95% of isolates, does not cross react with K9CV

– difficult to isolate

FeCV, serotype 2

Both serotypes can lead to FIP causing strains

epidemiology

• Exposure to FeCV– 25% of cats from 1-2 cat households are seropositive

– 75-100% of cats from catteries seropositive• susceptible cats become infected immediately following

exposure

• kittens can become infected in utero or soon after maternal antibodies drop below protective levels

epidemiology (FIP)

• 1:5,000 in 1-2 cat households

• 1:20 in catteries– sporadic– clustered (2-3 cats) - rare– rarely epidemic

• no gender or breed predisposition

FIP pathogenesisFEC

Mild diarrhoeaor respiratory illness

persistent infection

virus immune system

low level of replication in epithelial and lymphoid cells

pregnancy in young queens elective surgery

weaning, sale, shipment,adoption

concurrent infections (FeLV, FIV ?)

Virus immunesystem

increased virus replication -> virulent mutants

increased ability to grow in macrophages

immune-mediated lysis of infected cells

cytokines draw in more susceptible cells

vascular permeability

immune complex related damage

M.C. Horzinek and H. LutzAn update on FIPVeterinary Sience

TomorrowJan, 2001

www.vetscite.org

clinical signs

• common signs– chronic antibiotic unresponsive fever– progressive anorexia, weight loss– stunting of growth

• blood abnormalities – progressive increase in serum proteins– increase in globulins– anemia– serum, urine brown due to bilirubin

clinical signs

• “wet” form (poor cell-mediated immunity)

– peritonitis– pleuritis

• “dry” form (some CMI)

• granulomas

• enlarged lymph nodes

• cloudiness in eye

• neurological signs

• can change from dry to wet

Sharif et al. 2010. Vet Med Int

diagnosis

• RT-PCR for FeCoV• Serology (ELISA for anti FeCoV antibodies)

– prognosis?• no titre - no FIP but may still be infected• <100 - less chance of developing FIP• >100 - greater chance of getting FIP

• increased globulins and protein (>35g/L)• cytology

– degenerate and non-degenerate PMN, macrophages, some lymphocytes, protein background

– FeCV positive cells (FAT)

control

• vaccine– Primucell FIP

• Intranasal ts virus

• management– early weaning and separation