Please take a minute to respond about today's lecture, focusing on what was taught about health surveillance systems, and two cases on foot and mouth disease and bovine tuberculosis. Did you have any questions about the surveillance concepts? Do you want more information about these diseases (epidemiology, pathology, etc)? Are there any surveillance considerations that you thought were overlooked or might be better developed?
Thinking about health surveillance systems
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Three main points
**Not only does Surveillance include on-going assessments of health and disease status of a population but it also implies that action will be taken if critical threshold of a disease is reached.
**Guidelines for evaluating public health surveillance systems include: simplicity, flexibility, data quality, acceptability, representativeness, timeliness, stability, sensitivity, and positive predictive value. However, sometimes attributes may not all be reached and some may require sacrificing for others (PPV vs. sensitivity) etc.
** Uruguay has a very costly and inclusive/efficient surveillance/prevention program for FMD, but is cost effective since 6% of Uruguay GDP is from livestock.
One question
**Wouldn’t it be more cost effective for the US to have a thorough FMD vaccination program like Uruguay before waiting for the disease to slip in its boarders or a terrorist attack?
Three main points
- surveillance involves many different aspects involving ongoing assessments, testing of disease and response to an outbreak
-Uruguay utilizes an FMD free vaccination protocol that is effective, even if it isn't very simple
-when testing for FMD, can get cross-reactivity with other Picornaviridae
One question:
If Korea has had outbreaks before, why do they not allow product from Uruguay if they are considered FMD-free?
Three Main Points:
*FMD is a very contagious disease of cloven hoofed mammals which Uruguay has a very complicated system of watching, but that is very effective and accepted in their country for the protection of the beef industry.
*Slaughter house surveillance is important for the protection of the US food supply to prevent the transmission of zoonotic disease and foodborne pathogens.
*Surveillance is more than just monitoring disease because it has a component of action should a disease outbreak be detected.
Question: How does the US perform FMD surveillance, and what are we currently doing to prepare ourselves for the event of an outbreak in order to protect our beef and dairy industries?
1) Surveillance can sometimes be more cost-effective than waiting for outbreaks, especially if the system is thorough but not overburdensome.
2) Making sure that the system is confidential is important to improve acceptability. If people don't trust the system, they won't want to participate.
3) Sometimes purposive samples are more useful for testing disease, even though they are biased in a non-random way. It can help reduce errors overall.
?) Although levels of prevalence and desired confidence vary, is there a minimum level of sensitivity (or positive/negative predictive value) that is generally required for the test to be considered useful? This decision would be affected by the risk of the disease and the cost of the test, but at what point do you not bother to test?
Three Main Points:
1- It is impressive to see and try to understand the different surveillance systems throughout the world. Although, we were just introduced to 2 different types of surveillance programs (Uruguay and USA); there are a lot of different aspects that depend on the goals and economics of the country.
2- FMD is a fascinating disease to me. It is very fascinating how during the 2001 outbreak Europe decided to choose the technique of stamping out and Uruguay choose to vaccinate. In the end Europe spent a lot more money than Uruguay did. I wonder if Europe made the best decision?
3- The slaughter house surveillance system is one that seems to be a great mechanism of trying to detect any ongoing disease within the USA. But up until today I did not realize that it is not perfect. Detecting a disease after it has been sent to the slaugter house may be too late for controlling an outbreak.
Question:
What is the USA planning to do if they have an outbreak of FMD?
-Re:surveillance, it was interesting to me to realize that this is a system, rather than a means to study a particular disease for publication. As a system, it becomes more complex from the beginning.
- RE: FMD; The amount of effort that Uruguay has to put into tracking the potential incursion of FMD from neighboring countries is astounding. The US is indeed lucky to be free of this disease and seemingly isolated enough to prevent natural introduction of the virus into our livestock.
-RE: Bovine TB, we touched on this subject briefly. I think I had forgotten that Bovine TB has zoonotic potential. Especially considering that risk has been mitigated in the US via the paseurization of milk.
Three Main Points:
1. There are 3 international FMD recognitions: free with vaccination (e.g. Uruguay), free without vaccination (e.g. U.S.), and infected (endemic) - these different recognitions have the ability to affect trade.
2. Uruguay has all of those practices in place to detect and prevent FMD in order to protect their livestock agriculture industry and to maintain trade with other countries.
3. The main difference between surveillance and monitoring is that with surveillance there is a dissemination of information in order for an action to be taken.
Question:
What current plans are in place to counteract an FMD outbreak in the U.S. - how quick are orders given to depopulate (if that is the decision)?
Three Main Ideas
-Guidelines used in evaluating public health surveillance in the US
-Uruguay's complex vaccination protocol and testing antibodies for vaccine effectiveness
-Importance of having a few slaughter plants with respect to the amount of farms, allows for ID of pathogens
Question: Economically, would it be more expensive to cull all herds or be considered FMD positive country and vaccinate animals with the eventual hope of becoming FMD negative again?
Three main points:
- Finding a good surveillance method is often based on finding a good balance between sensitivity and specificity.
- Surveillance is more complex than monitoring and requires formulating an actual plan of action.
- Uruguay is an excellent example of showing surveillance flexibility in that "stamping out" is not economically feasible, and vaccination, while less desirable to certain countries, ends up being an effective solution that preserves most export capital.
Question: Vaccination seems to be an acceptable control method of FMDV largely because it is not a public health issue. What if there were a similar situation of a high income livestock being the source of a human health concern? How would you plan/prepare for an outbreak, and how would you balance human health vs human income?
Three Main Points:
1) The difference between surveillance and monitoring is that surveillance implies that action will be taken if level of a disease reaches a critical point.
2)The amount of sampling differs depending on whether you are estimating prevalence or detecting presence of a disease. Usually more samples are needed for estimating prevalence.
3)FMD is the most contagious disease of mammals, and countries can have one of three international statuses: free without vaccination, free with vaccination, or infected.
Question: Is the US currently working on implementing a policy where all livestock need to have an RFID, and if they are, where are they in the process?
1. Surveillance is a flexible system that can be used for many health concerns.
2. Identifying the sample size to use depends on many factors such as the desired precision or prevalence.
3. Slaughter surveillance is important since many diseases of cattle that don't cause clinical signs, can cause severe disease in humans.
4. Question: Was it the FMD outbreak in Uraguay that caused the increased response? It seems like most of the surrounding countries have not treated the disease as seriously. What role does economics have (did Uraguay have more money initially to invest in such a costly system)?
Three Key Points:
1)Surveillance systems are used in the prevention and control of adverse health events by collecting, analyzing, and implementing an action if a threshold is met.
2)When looking at FMDV surveillance systems (Uruguay in particular), the benefits (economic) can out way the negatives even if costly and complicated to implement.
3)Due to the concentration of product, slaughter plants are an ideal and opportunistic place to implement surveillance.
Question - In the US a national animal ID is not implemented. What are the main reasons for not implementing a ID system and do the benefits out way these reasons?
3 main points
1. There are many factors (attributes) that are involved in a surveillance program. It is important to make a system that is both sensitive and effective, yet somewhat simplistic in nature, so that there is less of a chance of confusion.
2. Prevalence plays a big role in determining sample size. Also, it is important to understand the difference between sample size calculations when looking at determining prevalence vs detection, as they vary quite a bit.
3.I was excited to hear that some countries are using surveillance systems along with vaccination protocols to both prevent and recover from an FMD outbreak. This seems like an overall better situation for everyone (human and animal) and appears to work better than depopulation, at least in the specific examples.
Question:
Maybe this is a question directed more for a stats course, but are there more than one calculation for sample size? And if so, is there an advantage over using one or the other?
3 key ideas:
1. One infectious disease can cause a lot of expenses through vaccination for a country which is so dependent in meat export like Uruguay.
2. A poor country might have to use tests that have low sensitivity and specificity even though there are better tests available because of the cost. But if they get a lot of false positives and have to kill every animal it still gets pricey.
3. It was interesting to learn about surveillance in FMD in Uruguay because in my studies we only concentrate in European cases.
Question: How do you trace the animals back to the farm if they don’t have individual eartags? There must be some information even in a herd level.
1. Surveillance systems are always a balance between desired outcomes and available resources.
2. While simplicity is an asset for a surveillance system, at times very complex systems are created to detect and monitor disease. The economic motivation for Uruguay to create a system with a high degree of sensitivity seems to have overruled simplicity.
3. Acceptability would seem to be a more important part of an animal surveillance system than one set up to monitor disease in humans because of both the potential economic impacts and the ability of farmers to not participate in a surveillance system.
?. In the US, which local, state, and federal agencies have the power to create surveillance systems and enforce extreme measures such as “stamping out”?
(from maher140)
a) It is amazing to see the thorough system of surveillance in Uruguay balancing real time issues of cost and efficacy
b) The co-operation of the South American countries was impresssive -- disease surveillance is surely not a one man's or in this one country affair
c) I was intrigued by the fact that surveillance includes an improved understanding of the public health implications -- This brings tot he surface the complimentary role of risk communication and surveillance
Question:
At what (point) in your surveillance program do you stop active surveillance activities.
(from punya003)
1. The difference between monitoring and surveillance is that surveillance includes the action to be respond
2. Sampling and test performance (sensitivity, specificity) are important for surveillance)
3. Surveillance system requires many components such as simplicity, flexibility and representiveness.
Question: How to evaluate the surveillance system? Good, moderate or need to be improved for example.
Thanks Jeein for posting my comments; i appreciate. I think the blogging idea is good helps extend some great discussions beyond the classroom.
Thanks Jeein for posting my comments; i appreciate. I think the blogging idea is good helps extend some great discussions beyond the classroom.