Saturday, January 31, 2009
For more information, check out this article in The New York Times.
Yeah, this seems very inaccurate. If we're talking about "total amount of terror," it should go down the more people get zombified. If, as seems more likely, we're talking about the amount of terror in the average non-zombie, it still wouldn't be a smooth curve like that. It would plateau pretty damn early. The difference between 0% and 10% would be a lot bigger than the difference between 10% and 90%. And 100% wouldn't be zero terror, it would just be N/A: there is no more population.
This is directly relevant to SIR models because you can easily get confused if you fail to distinguish between individual and population level parameters. The confusion here is because 'terror' is not defined - is this your individual level of terror (a feature of the number of zombies and their fearsomeness), or the total amount of terror in the population (a feature of the number of zombies and their fearsomness AND the number of unzombified people around to be scared by those zombies).
Friday, January 30, 2009
Some of you may be familiar with the programming software Mathematica, which has many tools for manipulating and visualizing mathematical models. Now before you zone out, take a look at this: an interactive visualization of the SIR epidemic disease model that allows you to see how changing parameters like number of contacts and fraction immune affects disease dynamics. You can play with the sliders to change parameter values, and the graph of the number of susceptibles and infecteds changes automatically. It is a very cool way to get an intuitive handle on how the SIR model works. Think about how the quantities you can manipulate in the Mathematica demonstration relate to the parameters we discussed in class: beta and gamma. Note that the model they use does not have a Recovered/Removed class--only susceptible and infected.
In order to play with the demonstration, you have to download a free copy of Mathematica Player 7 (the site will walk you through it when you click on the demonstration). It is totally worth it because I'm telling you, this demonstration is cool and it will really help you understand how the epidemic model works. If you get into it you can search Mathematica's demonstration website and find other cool ones. It's good geeky Friday fun.
Syphilis, caused by a spirochete bacteria, was first reported in Europe in 1495 and there have been a number of hypothese to explain its relatively recent appearance. I briefly mentioned the possibility that the Black Death may have played a role in its emergence.
For a long time the emergence of syphilis was associated with the discovery of the New World and is sometimes cited as being the only new disease to make the journey from New World to Old World (lots of diseases made the journey the other way, and diseases like smallpox and measles decimated the New World populations). But other diseases such as Yaws, caused by the same species of bacteria, have a widespread distribution in both the New and Old World.
A paper this week in PLoS Neglected Tropical Diseases provides evidence from a phylogenetic study that suggests that while other forms of the Treponema pallidum bacterium have plagued humans since early in our evolution, it emerged as venereal syphilis only when carried back to Europe by Columbus and his crew.
Thursday, January 29, 2009
The National Geographic magazine had this running article: Bubonic Plague Traced to Ancient Egypt
Panagiotakopulu came upon clues to the plague's presence in ancient Egypt by accident. She had been looking at fossil insect remains to learn about daily life more than 3,000 years ago.
"People lived close to their domestic animals and to the pests that infected their household," Panagiotakopulu said. "I just started looking at what diseases people might have, what diseases their pigs might have, and what diseases might have been passed from other animals to humans."
The researcher used a fine sieve to strain out remains of insects and small mammals from several sites. Panagiotakopulu, who is conducting similar work on Viking ruins in Greenland, said that looking at insects is a key way to reconstruct the past. "I can learn about how people lived by looking in their homes and at what was living with and on them," she said.
In Egypt Panagiotakopulu combed the workers'-village site in Amarna, where the builders of the tombs of Egyptian kings Tutankhamun and Akhenaton lived. There, the researcher unearthed cat and human fleas—known to be plague carriers in some cases—in and around the workers' homes. That find spurred Panagiotakopulu to believe that the bubonic plague's fleaborne bacteria could also have been lurking in the area, so she went in search of other clues.
Previous excavations along the Nile Delta had turned up Nile rats, an endemic species, dating to the 16th and 17th century B.C. The plague's main carrier flea is thought to be native to the Nile Valley and is known to be a Nile rat parasite.
According to Panagiotakopulu, the Nile provided an ideal spot for rats to carry the plague into urban communities. Around 3500 B.C., people began to build cities next to the Nile. During floods, the habitat of the Nile rat was disturbed, sending the rodent—and its flea and bacterial hitchhikers—into the human domain.
Egyptian writings from a similar time period point to an epidemic disease with symptoms similar to the plague. A 1500 B.C. medical text known as the Ebers Papyrus identifies a disease that "has produced a bubo, and the pus has petrified, the disease has hit."
It's possible that trade spread the disease to black rats, which then carried the bacteria to other sites of plague epidemics. Panagiotakopulu suspects that black rats, endemic to India, arrived in Egypt with sea trade. In Egypt the rats picked up plague-carrying fleas and were later born on ships that sailed across the Mediterranean to southern Europe.
The first is a list of the glossary items we have covered to date and the second is a sample midterm. It doesn't have a full set of questions but it does have the same format and samples of each type of question.
I'd just got this stuff together and was putting together the midterm at the same time when I got hungry and went to the UCEN for lunch. I got the following fortune cookie:
Details can be found here:
According to this CDC video, the plague has been used as a weapon as early as the Tartars, who catapulted infected corpses into the city of Kaffa in an attempt to spread the disease. However, scientists believe that the city got the disease through flea-ridden rats. The Japanese unit 731, under General Shiro Ishii, also used the plague by dropping infected flea-filled bombs in China. The United States researched an offensive use of the plague but had difficulties maintaining its virulence. The Soviets, however, overcame the problem and according to defector, Dr. Alibek, are said to have 1,500 metric tons of the plague.
Video can be found here:
But I had totally forgotten the brief appearance of a group of 'flagellants' at the start of the witch scene. Classic.
Dog ticks, mostly prevalent in spring, do not usually bite humans--the only cases have been in the summer because the ticks do not respond well to high temperatures. However, the current rising temperature of the earth is causing a problem, in that dog ticks now have an increasing affinity to bite humans. This is confirmed in both history and experimental models, where "under the effect of warmth, it was as if the ticks had gone mad and started to bite humans."
Wednesday, January 28, 2009
The CCR5 story has attracted quite a lot of attention. Some argue that it was more likely to be smallpox than the black death that altered the gene frequency and others have shown that the mutant form of CCR5 does not appear to offer protection against the plague, in mice at least.
Previous posts of interest:
Tuesday, January 27, 2009
The blog gets between 30 and 60 unique visitors per day. It averages about 5 when the class isn't running so discounting this background rate and assuming a few people visit from more than 1 computer in a day then there's probably still between a quarter and a half the class visiting each day.
Most visitors come directly to the site but a few (probably mainly non-class visitors) find the blog via search engines. Given the eclectic nature of the blog people have found it using some very strange search terms. Here are a few of my favorites:
- cholera stuffed animal
- morticia addams nail varnish
- scrofula humor
- sports drinks
From lecture, we learned that while rare, bubonic plague still exists in North America, carried by fleas and the rodents they feed on. What rodents are these? In the southern U.S., it’s usually prairie dogs.
While the likelihood of a human catching bubonic plague from a prairie dog is not high, other problems exist from the high prevalence of plague in the prairie dog population. The largest is the risk that the plague poses to the black-footed ferret, an animal indigenous to the American southwest.
Black-footed ferrets are highly endangered, and the plague puts them even more at risk. Not only can they catch the plague from prairie dogs they eat, but the high mortality rate of the plague can nearly exterminate the prairie dog population, the ferret’s largest food source.
Right now, the National Wildlife Health Center is working on vaccines for prairie dogs and ferrets, to try and save both species before it’s too late.
The official, who spoke on the condition he not be named because of the sensitive nature of the issue, said he could not confirm press reports that the accident killed at least 40 al Qaeda operatives, but he said the mishap led the militant group to shut down a base in the mountains of Tizi Ouzou province in eastern Algeria.
He said authorities in the first week of January intercepted an urgent communication between the leadership of al Qaeda in the Land of the Maghreb (AQIM) and al Qaeda's leadership in the tribal region of Pakistan on the border with Afghanistan. The communication suggested that an area sealed to prevent leakage of a biological or chemical substance had been breached, according to the official.
The other week I was browsing news sites after reading the chapter in The Coming Plague about cities and their effects on disease ecology. One of the most interesting parts of this chapter was the discussion of Dengue Fever, and how the spread of this disease and the mosquitoes that carry it was always facilitated by human attempts to curb the spread of this disease. Mosquito control has been a big part of the spread (or hopefully lack thereof) of many tropical diseases. Dr. Latto even mentioned the funny thing about DDT killing Bolivian cats last week, and how that may have contributed to an outbreak of a very nasty virus. We have come a long way from DDT now, and vector control methods are getting pretty sophisticated.
Scientists have been searching for ways to reduce the population of tiger mosquitoes in the world, as they are the primary carriers of malaria. What better way to do this than to simply stop them from creating offspring? Now it looks like that is a possibility. If sterile male mosquitoes were released into the wild, theoretically the population of mosquitoes would decline. Some scientists have even discovered ways to genetically engineer mosquitoes that can't carry malaria or dengue. The problem with this theory has been that female mosquitoes can tell that these guys have been altered, and they don't find the new males attractive at all.
In this BBC article scientists explain that they have discovered what mosquitoes find attractive in a mate, and apparently it is perfect pitch! When mosquitoes mate they beat their wings to create a humming harmony, and females can judge the fitness of male mosquitoes according to how well they "sing" with their wings. Previously, female mosquitoes rejected the genetically altered males. Maybe by releasing sexy sterile male mosquitoes into the wild we could see some very interesting effects on the ecology of the tropical illnesses that they traditionally carry.
Monday, January 26, 2009
National geographic has a plague photo gallery with some nice, and not so nice, pictures.
Sunday, January 25, 2009
Professor Latto mentioned copepods being a reason for the re-emergence of Cholera. He said that the Cholera bacteria can remain dormant within copepods until conditions are suitable for the bacteria to re-emerge. I thought this was very interesting but I had no idea what a copepod was so I decided to show some videos on what it looks like as well as its behavioral actions.
Copepods are small crustaceans found in almost every freshwater habitat. They are extremely important to the global ecology of the ocean as they are prey for many sea animals. They are typically 1 to 2 millimeters with a tear-dropped shaped body and a large antennae. They have one single eye, and some may even be eyeless. Many of these copepods can be filtered out of water with a simply using a cloth filter.
If you want to see real videos of these interesting creatures, check out this link:
If you'd like to read a little more about zoonotic diseases National Geographic had a great article a little over a year ago: Deadly Contact: How Animals and Humans Exchange Disease
We will return to this topic, and the issue of bushmeat, when we talk about Ebola.
Details can be found here:
Saturday, January 24, 2009
The World Health Organization now puts the total number of deaths from cholera in Zimbabwe at 2,773 as of Thursday while the number of cases since August has exceeded 50,000. The disease has also spread to neighboring South Africa.
Even more concerning, the fatality rate continued to rise to 5.7% compared with the international norm of about 1%.
The situation is being exacerbated by the onset of the rainy season, by a movement of the disease to more rural areas and by Zimbabwe's economic turmoil. The Zimbabwe dollar is virtually worthless, because of hyperinflation. Last week, a new Z$100 trillion note was launched - worth about US$30.
Details can be found here:
Friday, January 23, 2009
Although it only causes a handful of cases a year in developed countries, and has been eliminated in some it still causes over 24,000 deaths a year in Africa, mostly children in poor rural communities.
A recent paper in the Journal of General Virology analyzed 182 samples of dog rabies virus from 27 African countries taken over a time period of 29 years. They showed that most of the rabies virus circulating in dogs in western and central Africa comes from a common ancestor introduced to the continent around 200 years ago, probably by European colonialists.
Dr Hervé Bourhy et al. Evolutionary history and dynamics of dog rabies virus in western and central Africa. Journal of General Virology, (in press)
For the picture to the right:
As Professor Latto was saying earlier today in class, Lyme Disease is much more prevalent on the East Coast. I came across this cartoon and thought it quite appropriate to today's lecture about coastal differences for the disease.
Thursday, January 22, 2009
While I was searching for these names, I came across two websites. The first, LymeBlog, contains news about Lyme disease, as well as the personal blogs of people who suffer from it. The second, TruthAboutLymeDisease, is similar, although it is geared more toward helping people discover if they themselves have Lyme disease, and what to do about it. The very existence of these websites does more to show the prevalence of Lyme disease today than any number of infected famous people ever could.
What's at stake is life or death.
Maybe my death can help other people so they don't have to suffer as I suffered for so long.
I was treated and then considered cured and went on to have two more children, I then gave it to them congenitally and they have been very ill.
The sad thing is that so many of these cases could have easily been treated if they had been caught in time, or if the doctors had even acknowledged that something was wrong with them.
The documentary also has a blog with information about the documentary and general Lyme disease news. For screenings near you or information on how to buy the dvd, check the website.
Wednesday, January 21, 2009
Lyme disease causes more than just physical ailments. Often times, when Lyme disease goes undiagnosed, the brain becomes infected, causing neuroborreliosis. Patients may appear to just be suffering from psychological problems, such as hallucinations, obsessive compulsive disorder, or manias. Referring the patients to psychologists or psychiatrists, physicians often do not diagnose patients who suffer from cognitive impairments with Lyme diseases. However, what they are suffering from is not created in their head, but instead by a bacteria which has created lesions in the brain. Much like syphilis, which can cause neuropsychiatric disease, once these sufferers are treated with antibiotics, they can return to a normal mindset (as long as brain damage is not too severe). A milder case of neuroborreliosis is encephalopathy, which results in a confused mind-state (i.e. inability to concentrate, lapses of memory, difficulty following asleep, and lethargy). Because these symptoms are not obviously associated with severe health problems, many Lyme disease sufferers live their lives unaware that they are suffering from this disease.
Check out this article, to read more about the psychological effects of Lyme disease.
Armadillos have proven to be very important in the discovery of cures for leprosy because they are the only animal in North America that have shown to be susceptible to systematic infection of leprosy bacillus. This report shows the findings from wild armadillos in Texas. This article is unsure of how susceptible humans are to contracting leprosy from armadillos, but through excessive handling it is shown that the risk becomes greater.
The article includes many graphs to show where the infection of leprosy was the greatest and how these armadillos possibly contracted the disease.
Hallucinations began, what I now realize were likely simple partial seizures, the result of lesions on my brain. I saw people walking into my room, two girls jumping rope, numbers spinning on an odometer, a fat poodle hanging from the ceiling.
and her difficulty in getting an accurate diagnosis and treatment:
after I started antibiotic treatment I took part in a study in which my blood was sent out to five different labs for the ELISA and Western Blot. The results were all over the place -with Lyme-specific bands lighting up in one lab and not the other. There was almost not a single consistency.
Tuesday, January 20, 2009
Some earlier TB postings you might find interesting before we leave this topic:
Monday, January 19, 2009
The clip cuts off before it is shown, but Mary's mother, father, and a majority of her servants die the morning after contracting the disease, illustrating cholera's high virulence; Mary goes to sleep with parents and wakes up the next morning an orphan.
Sunday, January 18, 2009
The picture above is from Wordle, a fun tool that generates “word clouds” from text. The clouds give greater prominence to words that appear more frequently in the source text. In honor of the 200th post on the blog I pasted in the entire blog and then just deleted a few words (‘posted’, ‘comments’,’label’) that automatically appear at the end of every post and aren't very informative. The remaining cloud is an interesting visual way of showing what this blog is about. Thanks to all the new posters this quarter - notice the prominence of ‘Cholera’ and Tuberculosis’, the two diseases we have covered to date.
In the early 1800s, morphine and opium were the drugs of choice for treating tuberculosis (and many other diseases). Drugs that actually cured the disease, or even its symptoms didn’t exist yet, so all that physicians could do was dose their patients with something to dull their pain. Morphine, along with its derivatives, including opium, laudanum (used to induce sleep), and heroin (good for quieting a cough), were perfect for this. Unfortunately, many doctors neglected to mention its addictive qualities, and patients were addicted before they knew it.
With the antibiotic resistance that many strains of tuberculosis are now showing, how soon before we're back to morphine with no other alternative?
For more about morphine and its role in Victorian treatment, click here or here.
“In almost every case and for all types of antibiotics tested, drinking green tea at the same time as taking the medicines seemed to reduce the bacteria's drug resistance, even in superbug strains, and increase the action of the antibiotics.”
In some circumstances, the killing effect of one antibiotic was 99.99% better when taken with green tea than when taken alone. To read about the full study, and what this will mean for the future, check out the article from Science Daily.
[As promised, penicillin!]
Saturday, January 17, 2009
In a series of laboratory experiments hydramacin was shown to kill a wide range of both Gram-positive and Gram-negative bacteria. Hydramacin works by sticking to the bacterial surface, promoting the clumping of nearby bacteria, then disrupting the bacterial membrane.
Friday, January 16, 2009
Details can be found at:
Although moderate exercise is good for your immune system there is an increasing understanding of the fact that a high training load can temporarily suppress the immune system. This is seen most prominently in marathon runners and ultra-distance runners.
This link has a simple discussion of some of the mechanisms involved and some of the studies that have demonstrated it. I was thinking of this because I was reading about the origin of distance running and came across a mention of Tuberculosis. Before motor cars the rich and wealthy would travel by coach and would employ 'footmen' who would run ahead to clear obstacles or summon help if the coach broke down or got stuck. As roads got better the demands on the footmen got greater and greater who as a result 'seldom survived three or four years, generally dying of consumption.' We can only assume this may have been a combination of crowded sleeping conditions on the road, mixing with a large variety of poor, and possibly infected people, and possibly a suppressed immune system from all that running.
As roads got better and footmen became unnecessary the rich found another use for them - race them and bet on the result! You can read an interesting article about the Basque running footmen.
Thursday, January 15, 2009
So this is now my second post and I decided I would focus my attention on short videos in order for all of you to gain knowledge through a different means then by reading. This video is about the discovery of Penicillin. We went over a lot of the details in lecture but in case any of you missed class or need a refresher this video is for you! Alexander Fleming is credited with the discovery of Penicillin after he left a petri dish out containing staphylococci. The bacteria seemed to be dying off because of a growth of what is now known as Penicillin. After his discovery Ernst Chain and Howard Florey further developed this antibiotic in order for it to be used in the human body. This video contains real footage of the laboratories and people involved in the discovery of this "miracle drug".
P.S. sometimes a preview for the history channel comes up first, but the video will appear right after.
Around 50 years ago society thought that antibiotics were the final answer to healing the ill and stopping the spread of disease, but within the past few decades we find this answer to be fleeting. Whenever someone uses antibiotics, a few germs survive and become resistant to the antibiotic. This happens especially when the drugs are cut off prematurely. Whenever antibiotics are used when are they are not needed or incorrectly, the resistant strains evolve and multiply creating stronger and more potent diseases. This video shows an example of the evolution of antibacterial resistance in order to better illustrate the issue.
However, when tuberculosis reappeared in Time’s top 10 lists in 2008, this time it was mentioned in the category “Top 10 Medical Breakthroughs.” Claudia Lorena Castillo Sanchez, a woman in Spain, had suffered from tuberculosis and lost function of one branch of her trachea. But doctors were able to line a donor trachea with Sanchez’s own adult stem cells (you can read more about it here) and now she is back to her pre-surgery life. While this transplant is still “experimental,” it does give hope for those who have suffered losses from tuberculosis or similar diseases, reinforcing the fact that science is always moving forward.
Staying on my “looking at the bright side” note, have you ever heard of GIANTmicrobes®? They are stuffed animals that look like different microbes—as the website says, “They're humorous, educational, and fun!” Each one comes with a picture and information about the real microbe it portrays, and if that didn’t sell you, they. are. adorable. Well, mostly. Anyway, I’m going to start posting pictures of them as they relate to the diseases we talk about in class. Hopefully it will add a little fun to your day. Here’s TB, and be on the lookout for penicillin sometime this weekend. Woop woop!
[GIANTmicrobes®'s stuffed animal interpretation of TB, pictured here with its microscopic picture and information card.]
Although the genus Penicillium is not particularly large it contains a surprisingly wide variety of both useful and nuisance species.
- Penicillium chrysogenum (was notatum) produces Penicillin
- Penicillium camemberti, used, you guessed it, to produce Camembert (and Brie) cheese. Antibiotic substances produced by the fungus help keep bacteria from consuming the cheese.
- Penicillium glaucum used to produce a varity of cheeses including Gorgonzola and Stilton.
- Penicillium roqueforti used to produce Roquefort and other blue cheeses.
- Penicillium italicum and digitatum these are the ones you'll find on your citrus, and are both seen on the orange above (the smaller, bluer colony is italicum). Like many Penicillium species they grow well at cool temperatures and will easily grow in your fridge.
- Penicillium expansum causes a soft brown rot of apples. The rotted part of the apple contains a mycotoxin called patulin produced by the fungus. If such apples are squeezed for juice then the patulin persists in the juice. Although patulin has strong antibiotic properties there are studies showing it has toxic effects on all cells (both human and bacterial) and there are therefore usually restrictions on how much patulin apple juice can contain.
- Penicillium marneffei is the only known species of Penicillium that can infect humans. It has recently been seen in AIDS patients in SE Asia with a fairly alarming incidence. 10% of patients in Hong Kong get Penicillosis (the disease caused by Penicillium marneffei).
Wednesday, January 14, 2009
Penicillin appears to be the “miracle drug” for treating bacterial infections. For some people however, use of the antibiotic can cause strong and sometimes deadly allergic reactions.
- Itchy skin
- Swollen lips, tongue or face
When patients do suffer a reaction, they usually receive an epinephrine shot. In milder reactions however, most people can use over the counter antihistamines such as Benadryl.
People with severe allergies often wear medical bracelets to warn medical workers not to administer penicillin if the patient is unconscious or cannot otherwise inform medics about their allergy. The bracelets are available at many places including Amazon.com (this one is made of Sterling Silver and sells for $175!). A common bracelet is pictured on the right.
Surprisingly, many people wrongly believe that they are allergic to the antibiotic. "Bad reactions" resulting in rashes and hives often occur.
These reactions do not necessarily mean a person is actually allergic to penicillin however. Of the people claiming to be allergic to the antibiotic, only 10% actually are. Testing for the allergy is done through either a skin or a blood test.
The New Delhi Tuberculosis Centre is affiliated with the Tuberculosis Association of India, which promotes Advocacy, Communication, and Social Mobilization (ACSM). Through these three strategies, the association hopes to increase detection and treatment of TB, as well as gain political involvement. TB rates in India have continued to increase, despite efforts by the government. Two people are dying approximately every three minutes due to drug resistant strains of the bacteria. The efforts by the centre and the government are being put heavily into research and social policies.
A common idea exists that says that the crews of explorers like Columbus and Pizarro introduced tuberculosis to the New World. However, analysis of Peruvian mummies says differently.
Spinal tuberculosis, which is much less common than the lung-based form (about a 1:4 ratio), leaves distinctive marks on the lower vertebrae. By x-raying remains, archaeologists have found these marks on many mummies. This evidence, along with DNA analysis, proves the existence of pre-Columbian TB.
What other diseases did the New World have before Europeans got there?
Extra: It turns out that scientists have been hypothesizing about the presence of TB in the New World for a long time. Go here to read a 1947 article that will tell you more than you ever wanted to know about spinal tuberculosis and Peruvian artwork…
If you weren't lucky enough to be in New York at the time, you can check out the blog they made. It has some of the sketches, articles, and maps from the exhibit. One particularly interesting entry was about an article from the Brooklyn Daily Eagle 1849 about children who would "play cholera."
It is hard to imagine the impact of penicillin in a world without antibiotics. Not only were many wound infections now easily treated but many other diseases could now be treated quickly and easily.
Tuesday, January 13, 2009
You can judge the success of World TB day in terms of raising awareness by whether you are aware of it or not. It's on March 24th every year to celebrate the day in 1882 when Dr Robert Koch astounded the scientific community by announcing that he had discovered the cause of tuberculosis. It is the brainchild of the Stop TB Partnership - established in the year 2000 with the goal of eliminating TB as a public health problem.
The World Health Organization is also working to dramatically reduce the burden of TB, and halve TB deaths and prevalence by 2015, through its Stop TB Strategy and supporting the Global Plan to Stop TB. What are they planning on doing differently this time, compared to the 1990-2000 attempt? Was the problem with funding (ie lack of), with their strategy or with the rise of AIDS and the interaction with Tuberculosis?
On a vaguely related theme, check out this earlier post on World Toilet Day.
Lots of controversy surrounds whether or not vaccines are overused in some cases, leading to strains of viruses that are resistant to those vaccines. With something as simple and relatively harmless as the flu, perhaps the vaccine should be reserved for infants and the elderly, whom the virus could do more damage to and the average citizen should have to deal with the sneezing and runny nose. It's a sacrifice I know I'm willing to make in order to slow the development of vaccine-resistant strains that could cause more damage in the future, but many people feel it is their right to protect themselves and their families, especially when a flu shot is so convenient and inexpensive. It's a debate that arises whenever a vaccination is made available to the general public and it seems impossible to determine which side of the issue is right, especially since it turns into a moral issue.
For more info on the Tamiflu-resistant flu strain, check out http://www.time.com/time/health/article/0,8599,1870601,00.html
Monday, January 12, 2009
Details can be found here: http://www.cdc.gov/ncidod/EID/vol10no7/03-0703.htm
We won't cover partner networks and superspreaders for another few weeks, and then it will be in the context of human diseases; however, the New York Times had an article today that links zoonoses (diseases that spread from animals to humans) and partner networks. The study, which involves dusting wild mice in Utah which are hosts for the Sin Nombre virus with vibrant powder, shows that a small number of individual mice are responsible for the majority of virus spread. These mice are called "superspreaders." When dusted mice contact other mice through mating or fighting, they leave behind powder on the other mice, allowing the researchers to monitor natural contacts between mice in the wild. These are the same types of contact that spread disease.
It is also possible, although far from certain, that this is the origin of the phrase 'daylight robbery' since the tax was widely seen as a tax on light and air.
Sunday, January 11, 2009
Next week we will talk a couple of times about what it is that actually makes us sick when we are infected with a bacteria. One of the most common ways that bacteria make us sick is when they either produce a toxin that they excrete (an exotoxin) or contain a toxin that may be released when the bacteria die (an endotoxin). A lot of the exotoxins are VERY toxic, some of the most toxic substances we know such as Botulinum produced by the bacteria Clostridium botulinum (see earlier posting 'Meet the Clostridiums'). In fact much food poisoning is a consequence of exotoxins. As you may have heard there is currently a Salmonella outbreak in the US possibly caused by Peanut Butter contaminated with Salmonella typhimurium. (You may want to check the recall details if you have "King Nut" or "Parnell's Pride" peanut butter).
All things considered you would think that Salmonella typhimurium would be about the last organism you'd want to take on a space flight. But no, intrepid scientists took samples of Salmonella typhimurium into space on a 2006 Atlantis mission. Curiously the bacteria became three times more virulent under the zero gravity conditions of space. SpaceDaily has quite a thorough report.
Although they used triple enclosed containers, and, I suppose, the consequences of dropping a container are less severe in zero gravity, the consequences of severe food poisoning in zero gravity just don't bear thinking about. Doh! Now I've gone and thought about it....
Saturday, January 10, 2009
We will be talking about these topics in week 3 but I thought this interview gave a nice sense of what scientists actually do, and some of the advantages, and difficulties, of taking an interdisciplinary approach.
Friday, January 9, 2009
If you look at the epidemic curve, although it doesn't show the increase from zero cases, you can see what is the broad, flat top of a continuous common source - an infected water supply. Imagine what this would look like if the disease was a) a point common source or b) a propagated source.
What is particularly tragic in this case is that until recently Zimbabwe had one of the best water and sewer systems in Africa. However after a decade of economic recession the infrastructure has collapsed, sewers are broken and there is no money to buy chemicals to kill bacteria in drinking water. NPR has run some reports on the situation and the outlook is not good.
The situation is likely to get worse now that Zimbabwe's rainy season has begun... because rain tends to carry untreated sewage into water supplies.
Thursday, January 8, 2009
When Hannibal’s army crossed the alps in 218 BCE, only half of his men survived. Could a disease like cholera have been responsible for these extreme losses?
Archaeologists and paleopathologists (those who study ancient diseases) already have the tools necessary to answer this question. By analyzing DNA from human remains, it is possible to discover what disease(s) a person had during their life, and what they died from. This technique has been used to identify leprosy victims from the first century, as well as the identity of the disease that killed half of Athens in 439 BCE (typhus).
The most likely candidates for killing off Hannibal’s army have been identified as cholera, salmonella, tuberculosis, diphtheria, and typhus, as these were all present at that time period. Hopefully, the Stanford Alpine Archaeology Project will get their funding, so we can know for sure!
The strangest part of this story for me is that scientists believe that the Tamiflu resistance mutation occurred spontaneously, and NOT in response to overuse or misuse of the drug (as is the case in most antibiotic resistance cases). The mutation is apparently “just a passenger, totally unrelated to Tamiflu usage, but hitchhiking on another change.” They suggest that the mutation first occurred in Norway, which does not use much Tamiflu.
The good news is that it has been a mild flu season thus far. For the most recent flu data for the US this year, check out Google's really cool flu trends site. They use search terms to track the incidence of influenza. Not only do they get it right (their data matches the CDC's), but Google's data comes out about two weeks before the CDC's. Note that my home state of Georgia currently has lower flu incidence than California.
Avoid raw vegetables.
Abstain from...ardent spirits and if habit have rendered them indispensible, take much less than usual.
Avoid getting wet!
The causes predisposing to CHOLERA are -
want of cleanliness of person,
intemperance in the use of spirits,
debauchery or excess of any kind,
sitting in wet clothes
For more information on the recent outbreak, follow this link:
Wednesday, January 7, 2009
Though bird flu is currently less pathologically dangerous than something like the Spanish Flu (which caused a horrific pandemic with a hefty mortality rate), no one knows what direction it will take. Without control, it could rapidly mutate into a very scary and contagious human flu.
So what are we doing to keep bird flu at bay? Oddly enough, we're vaccinating chickens! I wonder if chickens have to show their immunization records before they can work at McDonald's... as chicken McNuggets of course.
I like the way that the volunteers 'were required to pass a written examination to document their knowledge of cholera and the study design.'
Also note in the methodology how they neutralized stomach acid with sodium bicarbonate before administering the cholera. Rehydration used CeraLyte, a rice based oral electrolyte.
WHO and UNICEF publish their own reccomendations for oral rehydration therapy which is
2.6g of sodium chloride, 2.9g of trisodium citrate, 1.5g of potassium chloride and 13.5g of glucose per liter of water.
Gatorade has more sugar (about 4 times as much if my math is right) but less salts (about a quarter as much) but would still be better than water. And water alone would be better than dying.
Some sports drinks do contain close to this amount of electrolytes, particularly those aimed at extreme endurance athletes, triathletes etc. Of course you can always make your own (whether for athletic use or an unexpected bout of cholera). Here's a recipe from WebMD that uses regular household ingredients. Not suitable for children under 12 though, the sugar level is too high. Drinks such as Pedialyte, aimed at children, have a much lower sugar content. So it's fine for adults to use childrens' oral rehydration therapies but not the other way around.
Tuesday, January 6, 2009
"Listen to CFR experts Laurie Garrett and J. Anthony Holmes discuss the political and humanitarian crisis unfolding in Zimbabwe, including the recent outbreak of cholera."
Although the conference call is a few weeks old I thought you might find it interesting partly because you get to hear Laurie Garrett, the author of the Coming Plague, who is now a senior fellow at the Council on Foreign Relations.
Monday, January 5, 2009
WHO is maintaining a website that contains updates on the cholera outbreak in Zimbabwe.