disease prevention lectures 1-3

measuring disease frequency allow to understand:

spread, onset, duration, susceptible individuals and risk factors

basic measures of disease frequency

count, proportions, odds, rate

why count isnt that great

doesn’t account for the entire population. onyl counting the cases

prevalence is

how common a disease is in a population at a specific point in time

proportion of animals affected by a health disorder

disease burden

n and d measured at one point in time

incidence risk calculation

new cases/population at risk

incidence risk tell us

occurrence/frequency of new cases

getting better or worse

effectiveness of prevention and control measures

incidence risk does not tell us

total burden of disease

current infection

duration

number of old or ongoing cases

proportion of sickness

what does odds tell us

probability an event occurs v probability an event does not occur

incidence rate aka incidence density calculation

new cases/ animals at risk * time of risk

measures of association purpose

assess the magnitude of the relationship between the exposure to a disease and a disease outcome (smoking to lung cancer)

estrus day in dairy cows

day 21

prostaglandin

breaks corpus luteum

brucellosis and vaccine

zoonotic bacterial disease caused by brucella abortus in cattle

reproductive and regulatory implication

humans can get it by unpasteurized dairy products

exposure to aborted fetuses, placenta, uterine discharges

infected will remain a carrier for life

RB51 vaccine

clinical signs of brucellosis

late term abortion

retained placentas and metrisis

placental inflammation

reduced reproductive efficiency

leptospirosis

bacterial disease affecting reproductive and milk production

caused by leptospira spp

zoonotic

serivars: L hardijo (chronic herd infections) and L. pomona

spread through urine

leptospirosis clinical and production effects

reduced milk production and occasional milk drop

fever and decreased performane may occur

few clincal sings

abortions, still births, weak claves

reduced fertility

lepto diagnosis

maternal adn fetal serum , fetal kidney and fluids, maternal urine for culture and PCR

Bovine viral diarrhea

caused by bovine viral diarrhea virus

serotypes: BVDV-1 and BVDV-2

NCP strain are associated with persistent infection

Bovine viral diarrhea transmition and PI cattle

direct contact and infected secretions

fetal infection can create persistently infected calves

PI cattle don’t recognize BVDV as a foreign pathogen cant mount an effective immune response against BVDV

BVDV infection between days 40-125 of gestation

clinical and production effect of BVDV

reduced milk production

immunosuppression and increased disease risk

diarrhea, fever, respiratory disease and poor performance

repro effects of. BVDv

early embryonic loss and infertility

abortions and congenital defects

birth of PI calves after fetal infection

PI identification

ear notch in calves: immunochemistry PCR antigen capture ELISA

what happens after calving

myometrial contraction for expulsion of lochia

endometrial repair

clearance of bacterial contamination

resumption of ovarian function

most common reproductive disorders

retained fetal membranes: not released within 12-24hr 40-60 develop metrisis,

metrisis: inflammation of the uterus caused by bacterial infection

clinical endometrisis

subclinical endometrisis

closed, open, target, source and study populatoin

closed: no adds

open: leaving and entering

target: extrapolation of results

source: study subjects are drawn from

study: individuals included in the study

prevention stragetgies

vaccination, biosecurity, training, nutritional management

control strategies

isolation of infected, treatment programs, movement restrictions, surveillance

why are measures of diseases association important for animals health management

to better understand how to control and prevent the disese

RR=1

outcome of both groups are the same

RR >1 RR<1

>1: risk factors are associated with disease

<1:low risk for exposed group

OR=1 , OR > 1, OR< 1

OR=1: no association

OR > 1: positive association

OR< 1; inverse association (% lower in exposed group)

why is the date of conception a determination of the number of days between consecutive clavings

ovulation is hard to pinpoint, most accessible starting point

what proportions of embryos are lost during early gestation in dairy cows

d19 & d62

pathogenicity

ability for microorganisms to cause disease in a host

virulence

severity of disease caused by a pathogen

susceptibility

hosts immune/physiological status to respond to pathogenic infection

what cells are involved innate and adaptive immune response

innate: nonspecific, pattern recognition receptors in plasma membranes of the pathogen and damaged cells, production of cytokines and chemokines trigger innate immunity, natural killer cells

adaptive: memory t and b cells, selectively target after first exposure (vaccines promote)

what is plasma cell

specialized white blood cell that produces and secrete antibodies

what is the mechanism of action of anti-inflammatory drugs? what molecules and enzymes are involved

decrease histamine release and inhibit clotting by reducing fevers by inhibiting production of prostaglandins

COX2 inhibitors and Arachidonic

what are prostaglandins revalent in inflammation

nocioreceptors: sensitize pain nerve receptors

PGE2: act on hypothalamus to raise body temperature

stages of acute infection

acute infection

innate response first and recruit neutrophils

neutrophils phagocytize pathogens and release intracellular and extracellular enzymes that destroy microorganism and damage tissue

neutrophils are in pus bacteria tissue debris inflammatory fluids

vaccine types why considering the vaccine type is important for management and sucess

modified live, inactivated, toxoid, recombinant (subunit, mRNA)

cavvine selection should condier the target disease, animal population, safety requirements, route of administration, and management goals

what are the critical management factors to consider for a successful immunization program

when to vaccinate and what type of vaccine

most common failures of vaccination program

how the vaccine is preserved

timing og vaccine eg: durring pregnancy, stress,

what is passive imminite

there is no trasnfer in utero due to strucutre

what are the main benefits of feeding colostrum to newborn

immunoglobulins 80-85% IgG, nutrients, lactoferrin, hormones, growth factors adn cytokines

3 components of colostrum that begin to decrease after the first milking

nutreitns

immunoglobins

innate leukocytes and adaptive

neutrophil, eosinophils, basophils, monocyte

adaptive: lymphocyte

innate immnity main barrier

integument (skin)

mechanical barrier

exocrine glands:

sweat: antimicrobial peptides

sebaceous: inhibit microbial growth

other innate barriers

digestive tract: lysosomes and defensins

genitourinary system: acidic urine and vaginal secretion

respiratory system: filtering, tonsils, cilia, reflexes

adaptive immunity post vaccine

1. b cell receptors bind with antigen

2. b cell divides into active plasma and dromant memory

3. plasma cells produce abundant antibodies for several days

4. antibodies are secreted into the blood as gamma globulins

complement system

create holes in bacteria to kill them

activated by expsure to particular carbohydrate chains on sruface of bacteria

antibodies are produced against a specific forgein invader

nine palsd a proteins that are produced by the liver and circulate in the blood in inactive from

sequential activation leads to assembly of large MAC that attacks

recommendations of passive immunity in cattle

10% body weight within 2 hours after birth, feed other meals within 6-12rhs

200 lgG at frist feeding

BRIX >22%

IgG concentration >50g/l

quality numbers

very good >80

good 50-80

fair 28-50

poor <28

five Qs of colostrum

quality: lgG/L of colostrum

quantity: IgG intake

quantify: serum

quickness: 2hrs of birth then meal in 12 hours

quite clean: low bacteria load, storage, administration

chronic infections

bovine leukemia, tuberculosis, Johne’s disease, chronis MI, bovine viral diarrhea virus

population medicine

the science and practice that focuses on improving the health, welfare, productivity of food animals by preventing and controling the occurence of health disorders through management of health risks and the implementation of treatments and interventions at the population level