Category Archives: Danger danger danger!
Ashley Hiltebeitel (12 Micro) finds Ebola virus fascinating, and noted in the comment thread to the previous post that she is working on a research paper for her Academic Writing class on the topic! It is unclear exactly how big the outbreak is, and epidemiologists are using many approaches to define the size of it. Ashley presents one approach for finding out how significant the outbreak is in non-human primates, from a news alert on Science Daily summarizing a primary research article in the journal PLoS Neglected Tropical Diseases. Here is Ashley’s summary:
The Wildlife Conservation Society (WCS) has led a research that uses fecal samples from wild great apes to center in on the populations that have been infected with the Ebola virus. This discovery will change the way the Ebola virus is studied. Because it is hard to capture and sample the wildlife in West Africa, it makes it hard to figure out how it emerges and is maintained in wildlife. Using the feces from the great apes gives scientists a cheaper, more simple and non-invasive technique to acquiring information about the disease. This new methodology also gives scientists the fact that apes develop antibodies against a disease to survive just as humans do. They also developed a way to isolate the antibodies from the ape’s feces. 10% of samples from 80 free-ranging wild gorillas from five different habitats tested positive in showing the Ebola virus in their feces.
The worst ever human epidemic of the Ebola virus is ongoing right now throughout West Africa in Guinea, Liberia, Nigeria, and the Sierra Leone. The zaire species of the Ebola virus is the one responsible. This species has been the cause of major human outbreaks before as well as major declines in the chimpanzee and gorillas populations all over central Africa. The human outbreaks have followed the wildlife outbreaks in the past. They transfer to humans from eating infected wildlife. including apes and fruit bats. Therefore, this spillover from wildlife to humans could easily be avoided by not consuming dead wildlife or buying the bats that are sold as food in markets. Because there is no cure for this disease yet, barrier nursing, supportive care, contact tracing, isolation of those who become ill, and education of the public is the only way to try and stop the spread of the disease from human to human. This is much harder to do in less developed nations than the United States where the Ebola virus has emerged repeatedly.
Alain Ondzie, a WCS veterinarian, made a great point by saying, “If scientists can better understand patterns of Ebola virus infection in wildlife, the public health sector can be more prepared to prevent human outbreaks.” The presence of the virus in the ape’s feces shows that some apes survive the Ebola virus. It also shows the regions where the Ebola virus has emerged and which populations of apes are more prone to getting it. Further investigation will need to be done to to see if antibodies persist or whether they pose protection against future infection of the disease.
The benefits of collecting ape feces include being able to cover large areas of forest more quickly without the expense of capturing and handling the animals. It also opens interest to better understand the ecology of the disease and some management options. This could include the study of immune response that could be compared with the genetic information of individuals after an outbreak. Scientists could use this technique with other species that play roles in the transmission of the Ebola virus as well, including wild pigs and antelope.
The Centers for Disease Control and Prevention have taken the unusual step of revamping their main website in response to the significant outbreak of Ebola Hemorrhagic Fever in central Africa. Traditionally, outbreaks of this disease have had epidemiologists worried when they occur, but fortunately the severity of the disease also means that it outbreaks have been contained rapidly, and the number of deaths historically have not been high with at most a few hundred deaths. The mortality in all outbreaks however has been high, with up to a 90% fatality rate in a 2003 outbreak in the Dem. Republic of the Congo. Currently, no treatment or preventative vaccine exists for Ebola virus.
The current outbreak is historic in its severity; as of late September, an outbreak in West Africa has affected over 6000 people with about a 50% death rate. The origin of this and previous outbreaks is similar, with the virus moving from its native reservoir in bats to non-human primates, and then to humans. Outbreaks in human populations then occur when human to human transmission occurs with high frequency. The CDC estimates that this number of cases will continue to rise, with potentially 21,000 cases by the end of September, and estimates from the World Health Organization are similar in scope.
To curtail this rise in cases, immediate measures need to be instituted, primarily consisting of ensuring that sick individuals are cared for in equipped Ebola Treatment Units, or if full, in home/community settings with appropriate infection control procedures in place including safe burial procedures. The CDC currently has over 700 staff members actively working on the epidemic at labs in the US, and have deployed almost 100 specialists to offer assistance in the affected region. Part of their work oversees is to assist with screening measures to prevent the epidemic from spreading to other regions, and ensuring that medical and humanitarian resources can reach the affected areas. For US citizens, a non-essential travel alert for this region has been issued.
Public health investigators think that the current outbreak is so severe for a variety of reasons. Seasonal climate variation has potentially created an environment where the virus flourishes in its animal reservoir, or perhaps facilitates transfer from the bat to other transient animal carriers. Development into the jungle has eased the movement of people into regions where the virus is natively found, making animal-human transmission easier. Additionally, political turmoil makes it more difficult for health officials to rapidly respond when an outbreak occurs, and the current outbreak region spreads over several political jurisdictions. Together, these factors have combined for a perfect storm enabling a much greater outbreak than previously seen. The good news in all of this is that there is an international response to the outbreak, and the likelihood of the epidemic spreading to the United States remains very small, even when patients are brought to the US for treatment.
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.
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.
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!
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 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.
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.