Category Archives: Danger danger danger!

Beware of the brain eating amoeba -Naegleria fowleri

Maria Allera (11 AM Micro) is worried about parasitic diseases, and with good reason. She found a news alert about the brain eating amoeba, which has long been one of my favorites. Who can forget this classic episode of House which featured Nagleria, and was one of the last times I got to trot out the #BOGUS hashtag? Let’s see if Maria can make us feel better about Nagleria:

Naegleria fowleri is an amoeba that takes residence in warm, fresh water all over the world. Just two weeks ago N. fowleri turned up in a water supply in Louisiana, causing the town to go into a state of emergency to provide bottled water for all the residents. N. fowleri can be found in any body of water, such as lakes, ponds, rivers and even manmade structures like pools or waterparks. The amoeba thrives in hot water and can also be found in water discharges from industrial plants.

When N. fowleri comes in contact with a human it makes its way into the body through the nasal passage, swims to the brain and causes an often fatal infection called Primary Amebic Meningoencephalistis (PAM). Some symptoms of PAM include headaches, fever, nausea, vomiting, hallucinations and coma; all of these can lead to death. Since the 1960’s only 200 conditions have been reported, unfortunately less than 5% survive. The infection can be diagnosed when examining spinal fluid under a microscope to identify the amoeba. Under the microscope the amoeba appears as:

Naegleria fowler is elongated, 15-30 μm, and feeds on Gram-negative bacteria. The cytoplasm is granular, has a single nucleus with a prominent and contains vacuoles. Blunt lobular pseudopodia are formed at the widest point. The flagellated form is smaller, with a pear shape and two flagellae at the broad end. N. fowleri cysts are round, 7-15 μm in diameter and have a thick smooth double wall. N. fowleri is thermophilic, preferring water temperatures between 35 and 46ºC (link here)

Within the amoebas life there are three stages. The first two stages, the cyst and flagellate stage, require low food supply and low temperature. When an amoeba is in the cyst or flagellate stage it cannot survive in human tissue. The human body is the perfect living condition for the trophozoite stage. The amoeba feeds off of the human blood cells, it reproduces by binary fission and destroys other tissues. As dangerous as this microorganism sounds, it all depends how it is ingested to determine if it will cause harm or not. If you consume water with N. fowleri in it, it will process through your digestive system without any health problems. This amoeba is only dangerous when it gains nasal access.

Naegleria fowleri in its trophozoite stage, from the CDC

Just like any pathogenic disease everyone wants to know how to prevent acquiring it and how to treat it if acquired. To prevent contracting N. fowleri, it is smart to not submerge your head in fresh water, especially if it is a warm temperature. Try to always swim in treated waters and don’t wash your nose out with fresh water. Do not use a neti pot to clean your sinuses, the water goes straight up the nose so if the water is effected you’re putting your body directly at risk. Unfortunately most infections of N. fowleri end in death, there are a few survival stories. There have been four survival cases in North America, a laboratory did testing and the CDC released

It has been suggested that the original U.S. survivor’s strain of Naegleria fowleri was less virulent, which contributed to the patient’s recovery. In laboratory experiments, the original U.S. survivor’s strain did not cause damage to cells as rapidly as other strains, suggesting that it is less virulent than strains recovered from other fatal infections.

Amphotericin B  was the most common medicine to treat amoebas. It’s inserted directly into the brain; however, this treatment usually fails. The CDC also has an investigational drug on study called Miltefosine for three free living amoebas including N. fowleri and it has had much better results.

Issues in the fight against antibiotic resistance

Development of new antibiotics versus appearance of resistant bacteria

Development of new antibiotics versus appearance of resistant bacteria

I apologize for the slow pace of updates this semester; it has been hectic, and scouring the news for alerts of general microbiological interest to post here has taken a backseat to grading for the past few weeks. However, I came across a review article from the latest issue of Trends In Microbiology that is timely with regards to our current class discussion about antibiotics and their place in modern medicine.

I have painted a less than rosy picture many times in this forum about the future of medicine, primarily as a result of the diminishing utility of antibiotics. The premise is this: the more antibiotics are used to treat infectious disease, the less they are ultimately effective as a result of the acquisition of antibiotic resistance. Indeed, the observation that genes conferring antibiotic resistance to today’s antibiotics have been found in thousands of years old samples of bacteria in permafrost suggests that acquisition of resistance is not a matter of “if it happens,” but rather “when it happens” to antibiotics that haven’t even been developed yet.

In our viewing of the Frontline episode “Hunting the Nightmare Bacteria” in class the other day, one of the most alarming points come out to me was the highlighting of the problem of who is supposed to deal with with looming catastrophe. The majority of the large pharmaceutical companies have pulled out of the antibiotic business due to a simple financial decision–it costs a tremendous amount of money to bring new drugs to market, and by their nature antibiotics give a very poor return on investment. At the same time, it was also clear that there is no national consensus to determine the scope of the problem or what the most appropriate response should be.

The review article takes the following stance; public health officials must be proactive in recognizing the severity of the issue, and governments need to take the lead in prioritizing antibiotic discovery in both academic and industrial settings. Public-Private partnerships (PPPs) have been established in small scale between not-for-profit charities, small biotech companies, and large pharmaceutical firms, however the lack of financial return has limited their effectiveness to date. The model however is valid, and if adopted large scale the financial burden of bringing these critical drugs to market can be distributed broadly between the academic, governmental, and industrial players. Such a model in the current political climate in the United States is difficult, but not impossible to propose. These organizations have successfully come into being in Europe which has traditionally had a more open interaction between government and industry, however the passing in the US of the Prescription Drug User Fee Act (PDUFA V) provides financial incentives for novel antibiotic development in this country. Hopefully, these incentives will allow medicine to stay ahead of antibiotic resistance at least for a little while!

Emerging viral disease in the Carribean

 This news alert has been popping up via several news sources over the past few days. I first saw it via the New York Times, however the video clip is a BBC news report detailing the regional response to this outbreak. Several islands in the eastern Caribbean Sea have been experience significant outbreaks of Chikingunya fever, a mosquito transmitted disease that fortunately has a relatively low mortality rate but a pretty high rate of infection. Indeed, the ease of infection in humans and the high level of debilitating symptoms of disease led several governments to consider Chikingunya virus in biowarfare programs before these were banned by international treaty. What makes this outbreak alarming is the rapid spread that the disease is making from island to island, and the fact that this is the first time that the virus has been seen outside of its endemic region in sub-Saharan Africa.


Chikungunya incubation in humans, via the CDC

Chikungunya fever is caused by an RNA genome virus; the most closely related virus that might be familiar to BIO230 students is the Rubella, or German Measles virus, which is itself showing a resurgence in the US due to failure to vaccinate. Unlike rubella, Chikungunya virus is transmitted by the mosquito when it bites someone after having a blood meal on an infected individual. The incubation period is usually under a week, then the patient will exhibit a high grade fever, fatigue, and moderate to severe joint pain. The acute phase fever will generally resolve itself within a week or so, however in Chikungunya the joint pain will persist for weeks to months afterward. The initial symptoms of fever and pain lead many clinicians to initially diagnose Chikungunya fever as Dengue fever as the two diseases share a broad geographic region, however the prolonged joint pain is NOT characteristic of Dengue. This fact has led some epidemiologists to suspect that the incidence of Chikungunya fever is more significant that what has been reported.

There is currently no treatment for Chikungunya fever other than supportive therapies including rest, fluids, and non-aspirin pain relief. There is also not currently a vaccine for Chikungunya fever, although some clinical trials do show promise. Infection and recovery from Chikungunya fever confers life-long immunity to reinfection, so the current outbreak in the Caribbean does offer the opportunity to observe the spread and control of a highly infectious agent in an immunologically naive population. The initial outbreak was on the island of St. Martin in December 2013, with 3700 confirmed or suspected cases on St. Martin and several other eastern Caribbean islands. The Centers for Disease Control and Prevention have prepared a response document to the current outbreak. The spread of the disease into North America is unlikely, but not impossible. The virus is transmitted by two mosquito species, Aedes aegyptii and Aedes albopictus, both of which are found in the southern United States however mosquito control measures are effective at limiting the numbers of these insects. In order for an outbreak to occur, it is also necessary to have a reservoir of infected hosts for the mosquitoes to bite–the outbreak is dependent on having a population of infected individuals AND adult mosquitoes to maintain the outbreak. Consequently, in geographic areas where mosquito activity is seasonal, these outbreaks will stop as the mosquitoes are killed by cold weather. The main danger to US residents is with travel to Chikungunya outbreak regions, and the CDC recommends that all such travelers practice good insect avoidance measures.

Science denialism

The last posting on the potential effects of poor vaccine coverage has led me to think about public perceptions on science. Although generally the public feels that science in general has an overall positive effect on American society, a National Science Foundation survey from several years ago indicates that people do not have a very good idea of exactly what it is that science does, or who scientists really are. Indeed, many public science advocacy groups such as the NSF linked above, as well as private professional societies (such as the American Society for Microbiology which I belong to) have turned to having pretty significant public outreach and education efforts as part of their overall mission. Even with these efforts, there remains significant public distrust towards the motives of scientists and and the practice of science  for specific issues. This distrust span a range of topics,  including very broad ones such as the analysis of historical and geological climate change or the role of biological evolution in producing the diversity of life, to rather narrow ones such as the effectiveness of vaccination on public health or the benefits/dangers of genetically modified foods. I think that distrust of ANY of these topics reflects two failures; one on the part of scientists to not properly frame topics adequately in a more generally approachable manner, and one on the part of the public to be educated on the basic principles of the scientific method, and a failure to distinguish between the concepts of causation and correlation.

I am actually OK with this to some degree; misunderstanding of what I do as a scientist can be addressed through conversation and explanation. In the case of the anti-vaccination movement, I think that much of the perceived public resistance comes about from the failure to understand causation and correlation. This is prompted by real fears drawn from personal experience–we have all seen commenters in various public forums describing how a family member suddenly “changed” after receiving a shot. Although anecdotal evidence has its place, these observations generally only relate one single incident with one single outcome, and neglect the many other variables that may also have led to the outcome. The challenge then is to convince people that causation can only truly be determined in conjunction in blinded, controlled studies that allow the manipulation of only a single variable.

I also looked at the other extreme of science distrust–these would be the extreme outliers in the Pew Study linked above–and did some simple Google searching for conspiracies relating to vaccination. I won’t link back to any of the sites I scanned, however it quickly became apparent that rational discourse is likely not to be very effective. The main arguments seem to be two-fold: governmental agencies are constantly working to exceed their bounds essentially in a move to keep the population under control through vaccination, and the pharmaceutical industry seeks to maximize profit margins by selling vaccines. One site I found spent several pages detailing the lack of evidence supporting the premise that variola virus is the causative agent of smallpox, minimized the health risks of smallpox outbreaks, and ridiculed the eradication effort using attenuated vaccinia virus. This type of denialism towards vaccination fortunately doesn’t carry much weight in the general public, however I am frequently dismayed reading the Letters to the Editor in the newspaper by local correspondents who put forward the same types of motives in their arguments in opposition to climate change proposals.

My hope to all who come into BIO230 is that we think carefully about things we hear, and ask lots of questions when we come across something that we don’t understand. I find intuition is frequently helpful–I may not know the particulars about a given subject, but I can sometimes sense that something doesn’t seem right. Consider the evidence that is used to back up claims that you may see being made, and think of an experiment that might disprove those same claims. And I think the best experiment is one that immediately leads you to think of the next experiment–you are truly thinking then.

The effects of vaccination on public health

Screenshot 2014-01-23 06.52.43I saw a link that’s been making the rounds via Twitter and Facebook lately, from the Council on Foreign Relations. They have put together an interactive map that allows you to focus on any geographic region and visualize reported outbreaks of a variety of infectious diseases that are currently highly preventable by vaccination. The map quickly shows some obvious trends–various diseases show regions where they are more prevalent, but the regions follow political lines, not naturally occurring geographical lines. For instance as seen in this graphic, diphtheria (whooping cough) and mumps outbreaks are prevalent in the United States, but are not significantly reported elsewhere in North America. Measles outbreaks occur with extreme regularity in Western Europe, but very little in Eastern Europe. Rubella (German measles) occurs in Eastern Europe and Japan.

A disclaimer on the Intro page of the website states its purpose; to promote awareness of a preventable global health issue. The site also allows you to download and view the dataset used to compile the maps. Interestingly, outbreak reports are not only taken from governmental public health agencies, but also from media reports, and indeed a spot on the webpage allows visitors to submit links to outbreaks that they might have come across. I suspect this practice leads to maps that might be useful from a broad educational standpoint, much as the site disclaimer suggests, however it is probably not appropriate for a true epidemiological estimate of the diseases in question from a global standpoint. For instance, according to this summary at the World Health Organization, the incidence of measles in the Russian Federation appears to be at a rate similar to that found in Spain, and furthermore measles, pertussis, and rubella have been increasing there each year over the past 4 years. Official numbers from the Russian government suggests that vaccination coverage is very good for many diseases, with the reported rate for measles vaccine coverage over 98% of the population. The United States in contrast has around 92% coverage. The rate of disease in Russia suggests several alternative possibilities; the rate of actual vaccine coverage does not accurately reflect the “official” numbers, or that the vaccine is not entirely effective in preventing the disease. The CDC indicates that the current two-dose vaccine regimen is essentially 100% effective in preventing disease due to all virus types.

Measles on its own is an annoying, but not particularly dangerous disease in most individuals. It is among one of the most contagious infectious diseases known however, and can be very easily spread through an immunologically naive population. Furthermore, complications arise in up to 20% of the cases, with a fatality rate in about one in 1000 cases. This fatality rate does not seem very large, however in the context of the number of cases in regions where it is still endemic, many deaths still occur. Because of the high infective potential, and the large numbers of cases worldwide, vaccination remains the best public health choice in this country.

Working on shaky ground

New Picture (10)Stefi Holtzer (12:00 Micro) found this story about dangers in the water back home. Here is Stefi’s summary:

Every summer I work at a boathouse in Rockville, Maryland. For the past two summers we have had signs posted all around the lake warning of contaminated water. This summer our boathouse was even interviewed and shown on the news, due to this problem. County officials tested the waters and claimed that the water was safe for individuals to stay in the vicinity, but unsafe if ingested in large amounts. Therefore the boathouse stayed open. Large controversy surrounded my area of work for the past two consecutive summers concerning a topic I knew little about. This all changed once I entered Microbiology class this semester. I find it interesting that the information I learned in this class touched on a topic so close to home for me.

A new piece of information I picked up working at the boathouse this past summer is that all lakes in Maryland are man -made. Due to such high amounts of fertilizer run off in suburban areas the majority of bodies of water in the Chesapeake Bay area are contaminated with the same microorganisms that Lake Needwood was. But what was this microorganism? We as Park staff were told that the water contained blooming Blue Green Algae scientifically known as Cyanobacteria, specifically it “contain[ed] strains of Microcystin, which can damage the liver and cause gastrointestinal discomfort when ingested and cause minor skin irritation upon contact” (Lui,2013).

To the common person who is uninformed on the classification of microorganisms this sounds extremely dangerous and makes it seem as though even being in the same vicinity of a body of water with this algae could be detrimental to one’s health. Even to an Employee in the loop on the status of the water safety, the water’s presence of this unknown algae frightened me, as it is common that we as park staff dip our feet into the water often as we load patrons onto boats. However, as I have almost completed a semester on Microbiology I know understand a lot more on the specifics of the issue.

Specifically, one concept I learned in class this semester is that the majority of algae species do not harm the human body. Unfortunately there are certain types of Algae blooms that can produce toxins that can affect a number of living beings including humans. However, simply touching contaminated water with the skin is not known to be fatal, only drinking large amounts is known to cause fatality.

In the article reporting the presence of Blue green Algae at Lake Needwood, it discusses that a park Patron, which was mistakenly reported rather than a park employee, took samples of the lake that were sent out to be tested  in order to determine the type of bacteria present. I along with my boss was the park employee who collected these samples and sent them to be tested. I find it ironic that only this past summer I had no idea what I was doing when I was collecting samples at work on a microorganism, but now I understand thanks to Micro lab and specifically, our water and food analysis lab what went into testing for the unknown in the water sample. It is very rewarding to me to be able to understand on a different level what exactly was wrong with the water I work with during the summer. My new perspective on the understanding of microorganisms and how to perform tests to identify them will better help me explain the health risks to park patrons visiting this coming summer.


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