Tuesday, August 27, 2013

Anthrax


This time on Infection Landscapes we will cover another zoonotic infection that has afflicted humans and their domestic livestock probably for thousands of years: anthrax. This discussion will focus only on zoonotic infections in humans, and to a lesser extent enzootic and epizootic transmission among animals. The use of anthrax as a biological weapon will not be covered here as this does not fall within the purview of Infection Landscapes.

The Pathogen: Anthrax is caused by the gram-positive bacterium, Bacillus anthracis. As indicated by the genus name, this is a bacillary, or rod-shaped, bacterium:

Bacillus anthracis rods

The organism is spore-forming and metabolically aerobic when active. The spores are extremely robust to environmental insult and, as such, can last for many years in the environment until favorable conditions emerge. B. anthracis initially targets macrophages in the host. Pathogenicity and virulence are driven specifically by the presence the bacterium's capsule and its production of endotoxins. The capsule prevents phagocytosis by macrophages and other phagocytic cells, and thus is able to evade an important arm of innate immunity in the host. The endotoxins are directly responsible for pathogenesis: edema factor mediates an increase in intracellular cAMP, which leads to severe edema in tissues, while lethal factor leads to tissue necrosis. Subsequently, the bacilli can be disseminated by way of the blood and lymph circulation.


The Disease. Anthrax typically falls into one of three distinct categories of clinical presentation: cutaneous, pulmonary, and gastrointestinal.

Cutaneous anthrax is the most common presentation in humans. Cutaneous anthrax typically presents with an abscess on the skin, which quickly progresses to a black eschar of necrotized tissue:



This kind of presentation generally follows transmission of the spores via open breaks or wounds in the skin following the handling or processing of infected animals. If treated effectively, cutaneous anthrax typically remains localized without generating a potentially life threatening toxemia. However, if cutaneous anthrax is not treated then the disease is subsequently associated with approximately 20% case fatality.

Pulmonary anthrax is a much more severe form of disease. Early presentation mimics an influenza-like illness, with fever, malaise, and cough. However, this can progress to fulminant disease and ultimate respiratory collapse, which is associated with a case fatality greater than 95%. If treated early, i.e. before fulminant disease ensues, this case fatality can be reduced by half. Pulmonary anthrax follows the inhalation of anthrax spores and is therefore known as "inhalation anthrax". However, the infective dose of pulmonary anthrax is much higher than for cutaneous anthrax (~10,000-20,000 spores).

Gastrointestinal anthrax is the least common disease form, but is also quite severe. Severe inflammation and lesions can present throughout the entire alimentary canal. Severe diarrhea and vomiting, both with or without blood, and anorexia are common early and persistent symptoms. The greatest threat from gastrointestinal anthrax results from the bacilli gaining the circulation from the gut tract, which can subsequently lead to a life threatening toxemia. Gastrointestinal anthrax typically follows the consumption of meat infected with B. anthracis. The case fatality associated with gastrointestinal anthrax can range from approximately 25% if treatment is initiated early to approximately 60% if treatment is significantly delayed.

The Epidemiology and the Landscape. There are three primary modes of transmission for B. anthracis infection in humans. Direct contact between breaks or wounds in the skin and spores in the environment or via infected animals is probably the most common route for human infection. Infection via this route is associated with cutaneous anthrax. Airborne transmission is possible when the spores are inhaled and subsequently initiate infection in the lungs, which has been associated with processing in certain kinds of animal industry. Infection via this route leads to pulmonary anthrax. Finally, food-borne transmission results from the consumption of contaminated meat. This mode of transmission is probably the least common in most endemic areas, however community outbreaks of gastrointestinal anthrax can be quite large particularly if infection is widespread among a herd of cattle slaughtered for food.

Global surveillance on anthrax incidence is quite poor, particularly in endemic areas. The map below, produced by the World Health Organization Collaborating Center for Remote Sensing and Geographic Information Systems for Public Health, depicts the general areas of endemicity by country across the world:


While the absolute numbers of incident cases are not likely to be high on an annual basis, large geographic areas of endemicity are apparent across much of the world including Central America, the Andean region of South America, sub-Saharan Africa, and Central, South, East, and Southeast Asia.

The landscape of anthrax is one delineated primarily by the spaces of interaction between humans and domestic livestock. More importantly, the specific kinds of animal processing in different kinds of industry define the types of interaction that can take place, and which may lead to transmission between infected animals, or their infectious products, and susceptible human hosts. The graphic below, prepared by the World Health Organization, demonstrates the primary routes of infection transmission (note: the route of vectored transmission by biting fly depicted by the dashed line is largely theoretical):


Where anthrax remains endemic, it typically infects the grass-eating bovids, domestic or sylvan, which encounter spores in the environment as they graze. Individuals working in industries that process livestock animals, such as cattle, goats, and sheep, in these endemic areas are at greatest risk of infection. More specifically, the direct handling of animal products in this setting is a common source of exposure. For example, the processing of animal hides for the production of clothing or other products that use these materials, such as drums, etc, can lead to contact transmission and subsequent cutaneous anthrax disease. Individuals involved with the processing of wool from sheep have historically experienced the highest risk of any occupation due to the significant potential for inhalation of the airborne spores in dust particles during the sheering of infected sheep as well as during the subsequent textile production. The latter route of transmission is quite uncommon today because most areas of the world where sheep husbandry is an important industry have eliminated anthrax in their animal populations. The two examples above illustrate how the landscape of infection can be comprised of intersecting physical and social spaces. In other words, risk of infection is not limited to those with direct contact with infected animals, but rather can extend to those who work with the products of those animals in occupational spaces potentially far removed from the original source of the pathogen.

Additionally, an outbreak of anthrax has been reported among injection drug users. Transmission in this scenario resulted from heroin contaminated with bone meal from infected animals. The bone meal is used to cut the drug prior to distribution.

Control and Prevention. Animal vaccines for livestock have been the cornerstone of anthrax prevention for more than one hundred years. Effective vaccination campaigns have reduced the burden of anthrax in livestock, and secondarily in people, in many parts of the world. The work of Louis Pasteur in the late 19th century, and then later Max Sterne in 1935, contributed to effective vaccination against anthrax in livestock animals. Louis Pasteur's anthrax vaccine was the first vaccine developed against a bacterium, and only the second vaccine produced up to that point in time (the first vaccine was developed by Edward Jenner against smallpox). Indeed, Louis Pasteur coined the term "vaccine". While Pasteur's vaccine was quite effective against infection with B. anthracis, it was also quite difficult to effect minimal virulence and maximal immunogenicity during the processing of this live-attenuated vaccine. Sterne was able to isolate a particular strain of B. anthracis that was much more amenable to efficient vaccine production and remains the current vaccine of choice for the protection of livestock in endemic areas of the world.

Human vaccines are also available in the United States, Europe, and China, but these are primarily used in military personnel among whom exposure to B. anthracis as a biological weapon may be anticipated. However, as described above, this form of anthrax transmission is beyond the scope of Infection Landscapes and so will not be discussed here.

Finally, the carcasses of animals killed by anthrax can be a significant public health threat if left unattended in the landscape. Specific measures to contain B. anthracis and prevent any further spread of the bacteria are critical interventions.

 
These carcasses must be removed to prevent contact with sylvan scavengers as well as to prevent contact with, and further dispersal within, the grazing lands of other domestic livestock.  Burning or burying of infected dead animals are common methods that have been used for centuries. However, these are by no means fail proof. In particular, complete burning of an infected animal (which would be required to eliminate all pathogenic bacilli) can take days. Such a fuel-intensive process may not be feasible in many, or perhaps most, areas of the world where anthrax is endemic. Burying is also a difficult solution because this must be done at quite a substantial depth to prevent the re-emergence of spores due to subsequent weathering and/or other erosional forces. It is important to keep in mind that if the spores are not destroyed they can remain viable in the environment for many years.

49 comments:

  1. I would think that a big portion of the problem is related to the fact that it is indeed difficult to get rid of the carcasses of infected dead animals. In areas where people have limited resources, a simple solution would be to leave the animals where they fall or congregate the carcasses in an area where other creatures can get to them. On the other hand, you have others who probably believe that the best solution is the bury them, but they would have to be aware of the fact that the bacteria can survive for years in unfavorable conditions only to resurface years down the line. They might believe that they successfully solved the problem when in fact they are simply keeping it at bay. People who live in endemic areas where the problem is mostly linked to infected animals would ideally need to be education on the proper methods of disposal. The next plausible solution would be to increase surveillance in order to see where there is a great need for animal vaccines.

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    1. The national bio security resource center suggests that incineration and composting are the best options for disposing carcasses while avoiding the spread of pathogens to humans. With education farmers can apply these methods and reduce the risk of spreading viruses. I agree that surveillance is needed to determine what areas are in need of intervention and are at a greater risk of exposure.

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  2. I think a significant problem is educating those who have to handle livestock. Here in the U.S., for those who work in a health-related field, we are highly aware of the threat of anthrax and possible ways to avoid it, so there are only sporadic episodes. But in these endemic regions, the resources to educate "farmers" may be lacking and they may be at risk without their knowledge. Not only that but it also is related with probability; since it is endemic in those areas, the threat of vulnerability is most likely less than if it were an epidemic. If the perceived threat is low, "farmers" may underestimate their actual risk.

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    1. Marc I agree with your point about educating those at greatest risk for anthrax infection. I would just add that it would be important to combine education about infection with the tools and supplies necessary to prevent exposure and infection. For example, appropriate protective gear such as gloves for those handling animal products or masks for people who work processing wool and are at risk of inhaling spores. We often focus on awareness and education, which is usually important but often not sufficient to reduce the problem.

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  3. Given the many modes of transmission, direct contact, air-borne transmission and food-borne transmission, it seems as though surveillance of anthrax should be of top priority. However, in endemic areas there is a lack of surveillance. These endemic areas are interacting with livestock in different ways and there needs to be more education to help those dealing with infected livestock in order for them to protect themselves from the threat of anthrax.

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    1. I don't necessarily agree. While you do raise a good point (as many of the other commentators have) that education is key in reducing endemicity, I do not think constant surveillance should be a top priority. Compared to many of the other infections around the world, anthrax seems to be less of an issue. Those resources could be put to better use elsewhere.

      As a side note, education and vaccination are probably the two most effective methods, but looking at the map I feel it would be hard to reach the more secluded endemic areas. This is also probably a major issue contributing to the burden of disease.

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  4. In countries such as India where livestock interact with humans regularly and without any boundaries, the risk of transmitting pathogens and developing infections is greater than in 1st world countries. Since it may be difficult and expensive to build irrigation systems, develop higher food safety standards, etc the best way to prevent the transmission of anthrax would be to educate farmers and livestock handlers about the dangers of handling contaminated soil and anthrax infected animals. Through education and general awareness of the problem, we can significantly reduce the spread of anthrax in developing countries.

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  5. I think that the general education on anthrax to the public remains the key, as the hyper-endemic/epidemic and endemic areas shown in the map above are mostly developing countries where health education is generally limited. The education on the lethality of anthrax and the modes of transmission would better help people protect themselves from the disease. On the other hand, the government agency plays an important role in monitoring the proper handling of the infected livestock, as some farmers without much knowledge simply want to get rid of the infected dead animals by disposing carcasses in the open area away from them—they do not even realize the fact that “the undestroyed spores are viable in the environment for years”. This would pose a serious problem and could cause another outbreak in the future.

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    1. I agree with you completely Wen D. People who don't want to deal with the Anthrax infested carcasses will just dump the animal as long as it is out of there hands not realizing that the spores can come back to infect later. This is why the general education of the public with Anthrax is so important and why the governments role is so important when it comes to education and not just the monitoring and handling of infected dead animals. Farmers need to know how and why to properly dispose of the carcasses and the government should let them be aware that if the animal is infected that federal funds will be set aside for the cost of proper disposal so that farmers do not feel that the burden of expense is on their backs.

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  6. As acknowledged above, the risk of anthrax infection is not limited to direct contact with infected livestock, but rather extends to those processing animal products, potentially at a distance, as well. This type of risk, for anthrax as well as other similar diseases, is important to recognize and address because it is not the immediately obvious concern. The less expected risks could potentially be more dangerous than the obvious ones since they might be more likely to go unrecognized, allowing infections to continue to spread.

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    1. I do agree with your point Rachel, I do know of a Nigerian drummer who works in Manhattan, he contracted Anthrax through untreated rawhide that he purchased in Nigeria. Fortunately, he did recover from it but he had a long road to recovery. I believe he was visiting Nigeria at the time and purchased it there but it goes to show that animal products are significant vessels for possible infection. The ultimate question is then, for these rawhides that are being sold to whomever needs them, are these hides coming from livestock who have died from anthrax with the carcasses laying around for how ever long or are these hides coming from animals being coincidentally butchered for their meat? In other words, the demand for animal products rather than animal meat may exacerbate the spread of anthrax.

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  7. I would like to know the epidemiology of anthrax in humans in South-East Asian regions. Kindly give references of the articles. I also would like to map of SE Asian countries with anthrax. My Email ID is -promila_r@rediffmail.com

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  8. Alexandr PinkhasovJune 18, 2014 at 3:56 PM

    Understanding the mode of transmission is essential to addressing concerns pertaining to anthrax related illnesses. Because the causative agent is a spore forming gram positive bacteria the disease is extremely hard to treat (the bacterium has the ability to evade the host immune system). The 95% case fatality rate suggests the importance of prevention of disease before a host becomes infected. People living in hyperendemic and epidemic regions should be taught methods of quick and safe-handling of carcass of those who died of the disease in order to prevent transmission. The fact that animal carcasses serve as a food source for scavengers, and a potential mode of transmission to other animals, raises concern because scavengers can move on to spread the bacteria over a wider regions within the environment.

    Although the article did not discuss using anthrax as a biologic weapon, Im interested to know how terrorists are able to harvest and disseminate the bacteria.

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    1. You make some very good points, Alex. As the article said, burning is highly fuel intensive, burying is potentially dangerous, due to the risk of exposure after erosion e.t.c. So, I wonder how widely the vaccine is employed in these endemic areas, both among human, sylvan, and other animal populations. As the safe disposal of carcasses that are infected is such a complicated matter, I wonder what means of prevention methods, if any, have been successful in endemic areas.

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  9. Modes of transmissions are very important for farmers to understand in livestock especially as it pertains to animal carcasses. It's understandable that it takes a long time to burn the animal completely, but I feel this is a necessity being that the a buried infected carcass that still cause infection for years. I also worry that there may be a possibility of the carcass affecting the ground water which may be used on farms and increase the oral transmission of anthrax. I myself was unaware of the 95% fatality rate of inhalation anthrax which can happen if not treated early. It concerns me that many people may confuse anthrax for flu based upon the symptoms that may present as well as doctors brushing these symptoms off as the flu since the flu can happen year round.

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  10. Anthrax commonly presents with flu-like symptoms as its initial presentation, which mays makes it difficult for a physician to identify as part of the differential diagnosis.
    A possible solution for your concern would be to implement biodegradable bags. When disposing of a carcass known to be infected with anthrax, a biodegradable bag will allow for the natural decomposition of the buried contents in a contained field, so that possible contaminants or sources of infection do not pollute the environment.

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  11. Stephen Budhu


    Epidemiology Comment 3


    Anthrax was of a particular interest of mine especially with 9/11 just passing, it reminds me of the post outbreaks. Anthrax stems from the bacterial group Bacillus anthracis, and it is a toxin that these rod shaped bacteria produce. With the target organism being the white blood cells, one can easily become immuno-compromised. The disease effects one of three regions: Pulmonary, GI tract, and skin. In all forms lesions are formed, which I would believe leads to other opportunistic infections. Most times anthrax infections are life threatening.

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    1. I remember post 9/11 how a person was busted in trying to send anthrax in the mail and how it took a while before he got caught. It's actually frightening that nowadays wars are being fought through chemical means. This means more than likely that other biochemical agents can be launched against a population.

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  12. I was wondering if there are any standard safety measures provided by the WHO or any public health agencies in properly handling the carcasses of animals killed by anthrax.

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    1. Yes,the WHO stipulates burning of the carcasses to destroy the spores,but this can conflict with air quality. Here is an interesting article from the New York Times archives:
      http://www.nytimes.com/2002/03/01/us/anthrax-expert-faces-fine-for-burning-infected-carcasses.html

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  13. The anthrax infection seems to be a very serious infection that can be fatal for the infected even with treatment. I am not certain how effective cooking of contaminated meat would be in preventing gastrointestinal anthrax since the pathogenic bacilli seems to be very difficult to destroy requiring complete burning of carcasses. Vaccination of livestock may be partly responsible for the food-borne transmission being the least common mode of transmission. In the food industry, are there State requirements for testing of cattle for anthrax before being certified fit for consumption?

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  15. I’m originally from Sudan which is an anthrax endemic country , people in the villages and parts of the cities interact directly with livestock on daily bases, In rural areas some families are living inside the cattle farms and with POOR education, surveillance and prevention system the risk of contracting the disease is quite significant and the situation is even more glaring in South Sudan because the majority of the rural population are cattle owners and there is an ABSENCE of the surveillance, prevention and treatment infrastructure combined with continuous tribal and military conflicts.
    In March 2011 there was seventeen reported human infection in South Sudan and in February 2015 three South Sudan nationals died at two different hospitals in neighboring Uganda, so cross-borders movements of live stocks between Sudan, South Sudan and Uganda and other neighboring countries make the effort to quarantine and incinerate the infected animal a difficult task.
    The vaccination programs are frequently running out of stock, personnel and funding and with the ongoing conflicts in both countries the surveillance and intervention is getting even more difficult.

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    1. Handling carcasses of anthrax-infected animals requires being able to identify the problem and also knowing that you should quarantine and incinerate the animals. I hadn't thought about the added obstacles (disorganized or absent surveillance, lack of government support/people to consult about the problem, safety, etc.) in endemic areas. Without the public health infrastructure in place, even people who are able to contain their outbreak can do little to prevent a future occurrence without vaccination or surveillance.

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  16. S.Wallace- Anthrax is clearly a serious infectious disease, and although there is knowledge about this disease, and its risk factors and treatment, there is still more research and education to be done. With recent discovery of Anthrax among injection drug users which was touched upon briefly. This new form of anthrax (injection anthrax) has only been identified recently in heroin-injecting drug users in northern Europe (never in the US) according to the CDC. I have to wonder about the significance of this issue and the impact it may have in the future on the ever present public health issue of drug abuse and overdose deaths.

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    1. The spread of anthrax through contaminated heroin injection among substance abusers in Europe has added yet a new dimensions to the challenges that already exist in combating, containing and eventually eradicating anthrax.
      Public health professionals, psychiatrist, infectious disease specialist and rehabilitation specialist has to work together to survey and research this new challenge and formulate a blue print to solve it.
      Given the increase in incidences of drug addiction among the youth and specially heroin addiction among the privileged this might pose a larger danger to the new generations.

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    2. The discovery about injection anthrax is truly shocking. These heroin users may not even know that what they are injecting is anthrax; it may be being passed off as a tainted form of heroin. I do believe that this will pose a new issue in the public health world about drug abuse. Those who drug traffic heroin and this injectable anthrax into the United States will endanger users who do not know exactly where their drugs are coming from. This will cause the mortality and overdose rate of heroin users to increase even more so than it has over the past few years.

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    3. Yeah I'm with Stacy. I am shocked that anthrax (by way of bone meal from infected animals) can be transmitted through heroin injection. The CDC has a short blurb about injection anthrax; the only cases have been reported in Northern Europe. So far, no cases of injection anthrax have been reported in the United States. Since the symptoms of injection anthrax can be similar to cutaneous anthrax it can be harder to diagnose and treat. Interestingly, the CDC did not report incidence rates or when cases of injection anthrax started being reported, both if which I would be curious to know.

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  17. This article is very insightful and I think that it does a great job in establishing the foundation in understanding what anthrax is, how it is transmitted, where it is found, the symptoms and effects, and current treatment used if one is infected. It also goes into detail about the methods that are used to destroy anthrax in cattle (burning and burying) and states that these methods are not fail proof. So I have two questions: first, is there a full proof methods to destroy anthrax? Second, after one is given the treatment for anthrax does it heal the infected area? The article only states that is prevents the spread.

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  18. I found it interesting that the virus can last many years in the environment until the right conditions are secured for it to become active, along with a the cutaneous anthrax 20% case fatality rate and the pulmonary anthrax having a case fatality rate of greater than 95%, this seems semi alarming for those working with or around animals that are known to carry the infection. Since both cutaneous and pulmonary anthrax can infect humans from contact and airborne respectively, farm workers or other careers involving direct contact of livestock and animals should be conscious of having their animals vaccinated for anthrax as well as themselves. However, in some of the countries that have the highest incidence of zoonotic anthrax, they may not have access to vaccines for both animals and humans and this is where we have to really be concerned about global shipping and trading since, a fact I never knew until reading this, since anthrax can be transmitted by contact and exposed individuals from handling various parts of the animal from the meat to the skin or wool. I personally do not work with animals in live or deceased form but I am curious if there are some type of working regulations that warn employees for the possibility of anthrax and/or how to protect themselves? I also think its important to remind livestock workers that taking care of the deceased, infected animals can have a large impact on stopping the transmission of anthrax.

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    1. I think anthrax is caused by a bacteria? And while theoretically inhalation anthrax, the much more fatal form, can occur in people in contact with livestock, I believe this is fairly uncommon and is not a very imminent threat to all those who work with livestock, they are more at risk of cutaneous anthrax as opposed to inhalation anthrax. I think inhalation anthrax is much more associated with bioterrorism.

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  19. I was interested to read more about the pathogenicity of anthrax in this post given the heavy media coverage of it during the time after 911. This brings me to my question- why is anthrax such a viable candidate for bioterrorism when compared with other pathogens? Is it because of the robustness in its spore form? Also I found that an important distinction that this post made was that pulmonary anthrax is much more severe (much higher case fatality) than the cutaneous and GI forms.

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    1. According to the CDC, Anthrax is generally used because its spores allow for this biological agent to be present for a long time in the environment . The spores are also very small and generally undetectable so they are easily hidden in powders, sprays, or food as well.1 It also seems that the death rate through inhalation is much higher because of the swelling that occurs in the lungs after the spores are absorbed by the mucosa.2


      1. Cdc.gov. The Threat| Anthrax | CDC. 2016. Available at: http://www.cdc.gov/anthrax/bioterrorism/threat.html. Accessed January 28, 2016.
      2. Ph.ucla.edu. Scientists Learn More About What Makes Anthrax So Deadly. 2016. Available at: http://www.ph.ucla.edu/epi/bioter/sciwhyanthraxdeadly.html. Accessed January 28, 2016.

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  21. Even though I have read articles about anthrax prior to this one, I was not aware that a person could inhale airborne spores in dust particles during the sheering of infected sheep or during textile production. This is interesting since some of the people who work in this industry might not even be fully aware of this way of transmission. Therefore, raising the question of how well informed are these workers of all the modes of transmission and of the protective measures that should be taken to prevent infection? Taking precautionary measures such as the use of gloves, masks and regularly washing one’s hands, might not eliminate all possibility of transmission, but it can prevent some anthrax infection cases. Even though, according to the CDC, a person cannot “catch anthrax from another person the way you might catch a cold or the flu,” person-to-person transmission can be seen with cutaneous anthrax since the “discharges from skin lesions might be infectious” (CDC 2013). Meaning that even those who don’t have direct contact with these animals but who live with or are close to those who do, should also know about the protective measures they can take to reduce their risk of infection. It would be ideal for anyone who has direct or indirect contact with livestock to be informed of the modes of transmission, protective measures, and the proper disposal of infected carcasses. Correct disposal of anthrax carcasses and contaminated materials is imperative since, as mentioned in the blog post, the spores that are not completely eliminated, can remain viable for several years; thus, remaining a threat to us and to future generations.


    Works Cited
    Centers for Disease Control and Prevention (CDC). 2013. How People are Infected.
    [Internet] Anthrax. Retrieved from http://www.cdc.gov/anthrax/basics/transmission.html.

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    1. You bring up a very important point about the huge significance of precautionary measures when preventing new anthrax cases! Although the number of incident cases identified geographically have not been high, it is still important for workplaces that are at risk to ensure that all personnel are informed of the risk and knowledgeable of the appropriate precautions. Work environments where the risk is known should follow OSHA laws and guidelines to protect their employees. Most of the cases that have been identified were linked to unexpected workplace exposures to anthrax spores. For example, I found an article (see link below) that discussed the recent error by the Defense Department that mistakenly shipped live samples of anthrax to 24 laboratories in 11 states and 2 foreign countries. Accidents such as this could have potentially harmful and deadly effects when safety measures and protocols are not followed in the appropriate manner. There should also be regular training such as annual training at the workplace to remind employees regarding health and safety precautions that include personal protective equipment (PPE) which will help protect them against anthrax exposure.

      Anthrax accident: http://www.mprnews.org/story/2015/05/29/npr-anthrax

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    2. I actually have studied some the OSHA laws in an occupational health class I took last year. Many times occupational and environmental health problems escape detection for a variety of reasons such as not paying attention to some health problems, not including them in data collection systems, problems not being recognized as occupationally and environmentally related or not being reported because reporting requirements are not strict. For example, there is definitely a problem with big meat distributors and their lack of ensuring that all their workers know all the proper protective measures that should be taken when handling cattle. The following link provides information about appropriate personal protective equipment (respirators and gloves), employee exposure, among others https://www.osha.gov/SLTC/bioterrorism/anthrax/faqs.html.

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    3. Hi Karla, thank you so much for the link! I definitely agree with your comment that a lot of real occupational hazards are easily missed either from cursory inspection or just from slack reporting procedures/protocols. The link you posted provides some really good information on personal protective equipment, and I think even if we don't work in the meat industry, it is still good to know what types of gloves protect against anthrax. For example, the website says that nitrile or vinyl gloves are good enough to protect against cutaneous anthrax. This is reassuring because those gloves can be found in almost any supermarket, so they're easily accessible. However, it's important to note that the website also said that PPE that might have had contact with possible anthrax need to be disposed of in a leak-proof container. That container then needs to be disposed of as infectious waste, not regular waste. I think in a public health standpoint, knowing to correctly dispose of the PPE is just as important as knowing how to correctly use the PPE. Overall, the OSHA website has a lot of good information, and it even discusses how to protect oneself from possible bioterrorist cases, such as using mail to disseminate anthrax spores.

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  22. My only exposure to information on anthrax has been related to bioterrorism. I did not know that B. anthracis was actually endemic in certain regions, depending on the interaction between humans and livestock. All the more, this article highlighted the importance of infection control and vaccines in livestock and the food supply. Such measures are incredibly important in keeping diseases at bay, including fatal ones like anthrax.

    I think one of the most dangerous qualities of B. anthracis is its resilience to environmental stresses. Thus, how to deal with infected carcasses is of great concern. Although burial and burning are recommended means of disposing infected carcasses, improper techniques may allow anthrax spores to survive. I wonder if there is an effective chemical means to deal with infected carcasses, one this is cost-efficient and not detrimental to humans and the environment. Through a brief Google search, I came across the use of formaldehyde, a human carcinogen. I also came across lime and calcium products, which were previously recommended. However, recent research demonstrated that calcium actually protects anthrax spores, and thus, is no longer recommended.

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  23. This article was a great read, and definitely gave me more insight into what Anthrax really is. Anthrax took the news and media by storm about a decade ago, but I had not really known much about it. In fact, I had previously assumed it was a chemical toxin much like sarin. What I found particularly interesting, is how durable the B. anthracis are to the environment, withstanding extreme temperatures from burning infected cow carcasses. Given the resilience of B. anthracis, it is quite fortunate that they do not account for more fatalities, which I assume is some what attributed to the availability of vaccines.
    The staggering 95% case fatality rate of Pulmonary Anthrax was also quite interesting yet shocking. But this also brought a question to mind. It was mentioned that Pulmonary Anthrax or "inhalation anthrax" is caused by inhaling the spores directly. However, the animation in the second image (the one depicting how the spread of endotoxin "lethal factor" results in fatalities) shows how the anthrax could cause pulmonary blockage via the lymph circulation. Since the animation showed the initial infection could have occurred through skin, could this mean that in some instances, Pulmonary Anthrax can be caused by initial infection through the skin in addition to the inhalation of spores? Or is fatality by pulmonary blockage not the same mechanism as Pulmonary Anthrax and are different forms of the disease altogether?

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  24. The first time I heard about anthrax, it was on TV. At that time, there was a lot of fear over the possibility that Anthrax may be used as a bioterrorism agent. The news reported cases of a white powder in suspicious mail that was being sent to various political figures. Thankfully, those attacks stopped and the fear abated. Looking back, I wonder if, aside from providing vaccines to everyone, there are other ways to prevent or at least decrease the likelihood of getting an infection should one receive a mysterious envelope with while powder. For example, could one simply wash hands, don an N95 mask, and take a course of antibiotics to prevent serious illness?

    Also, in terms of prevention of the disease in endemic areas... Would providing anthrax vaccines be a good idea? Although it is a rare disease, it is a serious one, which may even lead to death. Currently, even surveillance is lacking. Perhaps cost is a significant hurdle in this region.

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  25. According to the CDC; if a bio-terrorist attack were to happen, Bacillus anthracis, the bacteria that causes anthrax, would be one of the biological agents most likely to be used because:
    * Anthrax spores are easily found in nature, can be produced in a lab, and can last for a long time in the environment.
    * Anthrax makes a good weapon because it can be released quietly and without anyone knowing. The microscopic spores could be put into powders, sprays, food, and water. Because they are so small, you may not be able to see, smell, or taste them.
    * Anthrax has been used as a weapon before.

    Following the anthrax letters sent through the postal service in 2011, a scientific experiment performed by a high school student, published in The Journal of Medical Toxicology, suggested a domestic electric iron at its hottest setting (at least 400 °F) used for at least 5 minutes should destroy all anthrax spores in a common postal envelope!

    http://www.nbcnews.com/id/11522143/ns/msnbc-the_ed_show/t/seventeen-year-old-devises-anthrax-deactivator#.VhXePXpVhBc

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  26. "While Pasteur's vaccine was quite effective against infection with B. anthracis, it was also quite difficult to effect minimal virulence and maximal immunogenicity during the processing of this live-attenuated vaccine."

    I am fascinated by this(and by vaccines in general). In terms of the production of the vaccine, they had to make sure they maximized the immunogenicity to get the most robust immune response while making sure to keep virulence low. Since the anthrax vaccine is live-attenuated it is possible for this to reactivate and cause infection, disease, and horizontal transmission. Has this been demonstrated or seen anywhere?

    "It is important to keep in mind that if the spores are not destroyed they can remain viable in the environment for many years."

    Based on this statement, I am going to make a reasonably educated assumption that anthrax cannot be eradicated.

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  27. Critical to understanding Bacillus anthracis infection, or Anthrax, is appreciating the expected ecological niche that it can be found in and recognizing other circumstance when it is not expected. Having a high index of suspicion for Anthrax with “flu-like” syndromes as well as cutaneous abscesses and eschar is critical in early detection and treatment. It is important to know what prevention and treatment is available in all settings. Prevention of Anthrax with vaccine is limited to those at greatest risk. According to the Advisory Committee on Immunization Practices (ACIP) recommended routine vaccination (pre-exposure vaccination) is utilized for those in high risk laboratory settings, those handling high risk animals and animal products, those in Department of Defense field positions, and those involved in environmental remediation of infected sites. (lexi.com/1302699) Inhalational post-exposure prophylaxis is available for those with exposures but no active infection. Also there is an Anthrax immune globulin (human) (AIGIV) which is available, but it would not be helpful in treating meningitis as it does not cross the blood brain barrier. Once infection has occurred, treatment (whether with ciprofloxacin, amoxicillin or doxycycline), consists of 60 days of antimicrobial therapy.

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  28. I find it interesting that the Anthrax vaccine was from the earliest vaccines. I would imagine pasteur would want to focus on far more prevalent diseases and also diseases that effect primarily humans. Perhaps it is due to the contagiousness or the severity of the disease. I would suggest the imperative to create a vaccine could have been financially influenced. The Anthrax vaccine saved large potential losses from livestock owners.
    In the post it says that the Anthrax vaccine is the second vaccine in history. I thought Pasteur first made a vaccine for Chicken Cholera and only afterwards used those principles for Anthrax?

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    1. Hi, The opportunity to make money from vaccines certainly exists, but the main motivation has always been to prevent disease and the suffering it causes. In Europe when Pasteur was working many more people lived near, or even with, their livestock so anthrax was a common fear for many people. I'm interested to look into the cholera vaccine you mention--I don't know about that and cholera was certainly a prevalent disease in Europe in the nineteenth century too.

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    2. I also found it interesting that the anthrax vaccine was developed so early in the history of vaccines. Perhaps this would be less surprising for those who work with livestock and are therefore more familiar with its use.

      According to the CDC’s historical timeline of anthrax, it seems as though anthrax was discovered and studied quite early, being used by Koch to develop his famous Koch Postulates. (source: http://www.cdc.gov/anthrax/resources/history/)

      In addition, Pasteur’s studies on anthrax were reportedly in response to a devastating epidemic of anthrax among livestock in France in 1877, which would have provided the economic incentive to develop a vaccine. (source: http://www.historyofvaccines.org/content/timelines/pasteur)

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  29. Understanding the science of spores seems to be imperative to understanding how to prevent and control anthrax. I find it very interesting that the anthrax spores are so difficult to destroy. As stated above, spores that are not destroyed can remain viable in the environment for years, but to eliminate all pathogenic bacilli from an infected animal, it could have to be burned for days. Given these challenges, this type of organism seems extremely dangerous. I wonder why there don't seem to be that many types of spore-forming organisms or that many large outbreaks of the infections they cause. Perhaps for anthrax specifically, the animal vaccines for livestock have reduced the spread of bacteria so effectively that it is not common enough to produce the number of spores needed to infect humans. However, anthrax and other similar infections could be significantly underreported due to poor surveillance. Nonetheless, I now have a much better understanding of why anthrax would be chosen to use as a biological weapon.

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  30. While I have been aware of Anthrax in terms of biological warfare, I was unaware of the Anthrax in the context of animal husbandry and processing, it is quite interesting. The physical and social landscape connection frames the modes of transmission as an occupational risk for those directly handling or in contact with infected animals via livestock production and those processing the products of the animals. Awareness, education, access and compliance is imperative for prevention and control. Having access to personal protective equipment is one thing but the education needs to be put in place on the why, the how and the importance of compliance. Additionally, in U.S. this should be implemented with cultural competence as immigrant workers are often employed in agricultural industry. Also, I think it would be important for the hunting community to be educated of anthrax transmission and safety measures as I would assume wild animals such as deer would not be vaccinated as animals for livestock production may be.

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