Guideline for facilitators
Answer Q1:
1. Verify more information of this event for example
a. Location of this farm, number of farm in this area and number of cows in
each farm.
b. Person who related in this event e.g. private vet and non-vet practitioner to
find more information of this event
c. Previous information of the disease e.g. laboratory testing, treatment
d. How many cow died
e. Etc.
2. Source that you can get these information
a. Private practitioner
b. Cooperative
c. Private inseminator
d. Etc.
Answer Q 2;
Meaning of “outbreak”
The occurrence of cases of an illness, specific health-related behaviour, or other
health-related events clearly in excess of normal expectancy. The area and the
period in which the cases occur are specified precisely.
Why can we call “outbreak”?
1. More than
a. Median number of cases in previous 5 years or
b. Average number of cases + 2sd of previous 5 yr Number
2. Cases linked to the same factors (cluster)
3. A single case of disease that has never been occurred before.
Possible objective of this investigation
a. To verify diagnosis
b. To describe this outbreak
c. To identified risk factor of this outbreak
d. To control the disease and give recommendation to prevent outbreak in the
future
Answer Q 3;
a. team component: vet epidemiologist, dairy specialist, laboratory person
b. Equipment: for blood sample, rat trapping, water container
c. Organization: laboratory, milk producer cooperation, artificial inseminator,
vet practitioner
Answer Q4;
From laboratory profile, it showed that many of infected animals have anemia (48%, 11 out
of 23) and lymphocytosis (64%, 16 out of 23). Blood parasite (Anaplasmosis) was found in
1 out of 5 samples. MAT test show sero-conversion to leptospira hebdomadis (40%, 6 out
of 14) but we cannot conclude it is current infection. Suspected pathogen for this outbreak
is viral infection and blood parasite. However, leptospira cannot be ruled out from source
of infection.
Answer Q5; differential diagnosis
- Leptospirosis
- Viral infection
- Blood parasite
Activities for identification cause of infection
- pair serum of leptospirosis
- identify viral infection and blood parasite
You need expert opinion for identification of pathogen
Part 3: data collection and analysis
Answer Q6;
Case definition should be defined base on the disease that was suspected and possibility for
obtain these information. It should be include time (at least 1 longest incubation before
onset of the first suspected case), area and character of animal such as type of animal, breed
, sex and clinical sign
Possible suspected case definition for this outbreak
Dairy cows in the village that have at least one of the following clinical sign from 1st
December 2007 to 13 February 2009
1. high fever or
2. Emaciation symptom that was able to observe by owner.
The confirmed case definition was difficult to define at this stage because unclear cause of
pathogen.
Collected data and sample; epidemiological data including clinical sign, data of onset of
individual cow, farm management. 2nd whole blood samples were collected for laboratory
testing. Fresh blood smear samples were also collected to detected blood parasite.
Answer Q7;
Describe the outbreak in time, place and animal
There is only one farm that affected in this outbreak.
Attack rate = 36*100/93
Mortality rate = 9*100/93
Case fatality rate = 9*100/36
Clinical sign of the infected cows are high fever (80%), emaciation (47%), pale mucus
membrane (40%) and having nasal discharge (17%).
Owner can observe the first sick cow in 7 January 2008 and after that many cow got sick.
Number of sick cow was highest in mid of January 2008.
The affected farm always move cow into the farm for replacement.
Most of cows had 4-fold rising antibody against Leptospira tarassovi (14 out of 15). It
showed that this farm was infected with leptospirosis.
Most of cows in farm A have antibody against BVD while a few of cows showed antibody
response in other farms. BVD is potential cause of this outbreak and it naturally suppressed
immunity of the infected cow. Anaplasmosis and leptospirosis can increase severity if there
is a BVD infection. Low prevalence of Leptospirosis and BVD in other farm ensure this
assumption. Bad farm management (introduction new cow and overnight feed of cows)
system leads to higher infection rate.
Answer Q8;
Usefulness of the hypothesis
- Can improve or confirm disease control strategies
- New knowledge
- Monitor characterization of disease outbreak
Possible hypothesis:
1. Prevalence of leptospirosis in affected herd was different from unaffected herd
2. Prevalence of Bovine Viral Diarrhea of affected and unaffected herd are different
3. The disease cause more severity in production period than no production period
4. Etc
Answer Q9;
Suggestion for disease prevention of in the village
- Avoid moving in the new cow into the farm during 1-2 months
- Eliminate vector or carrier for example blood sucking fly, mosquitoes, tick and
rat
- Training farmer for self-clinical observation of their cow
Suggestion for disease prevention in farm A
- Improving farm management e.g. do not leave feed overnight in the manger
- Rise the replacement cow by himself
- Etc