Trevor Blake: Parasites in the News
BBC: ‘Monastic’ Malagasy Bat Mystifies Experts
The bat, known as the sucker-footed bat, lives in Madagascar, and although it has long been known, its ecology is only just being researched. But new studies of the bat have revealed a curious phenomenon; they have yet to reveal a single female sucker-foot bat, despite having caught or sighted hundreds of males. No-one knows where the females live, or why they sexually segregate this way. [...] Something else is peculiar about the sucker-footed bat: none of those yet captured and released have been found to carry any parasites on their bodies. This is extremely rare, as almost all wild mammals carry so-called ectoparasites, such as fleas or ticks. But “no parasites is easily explained by the roosting habits in the partially unfurled leaves of Ravenala,” explains Prof Racey. These leaves are too smooth for arthropod parasites to stick to, so they cannot crawl onto the bats. That may be one reason why the monastic male bats choose Ravenala trees to roost in.
Carl Zimmer: How Microbes Defend and Define Us
Dr. Alexander Khoruts had run out of options. In 2008, Dr. Khoruts, a gastroenterologist at the University of Minnesota, took on a patient suffering from a vicious gut infection of Clostridium difficile. She was crippled by constant diarrhea, which had left her in a wheelchair wearing diapers. Dr. Khoruts treated her with an assortment of antibiotics, but nothing could stop the bacteria. His patient was wasting away, losing 60 pounds over the course of eight months. “She was just dwindling down the drain, and she probably would have died,” Dr. Khoruts said. Dr. Khoruts decided his patient needed a transplant. But he didn’t give her a piece of someone else’s intestines, or a stomach, or any other organ. Instead, he gave her some of her husband’s bacteria. Dr. Khoruts mixed a small sample of her husband’s stool with saline solution and delivered it into her colon. Writing in the Journal of Clinical Gastroenterology last month, Dr. Khoruts and his colleagues reported that her diarrhea vanished in a day. Her Clostridium difficile infection disappeared as well and has not returned since. The procedure — known as bacteriotherapy or fecal transplantation — had been carried out a few times over the past few decades. But Dr. Khoruts and his colleagues were able to do something previous doctors could not: they took a genetic survey of the bacteria in her intestines before and after the transplant. Before the transplant, they found, her gut flora was in a desperate state. “The normal bacteria just didn’t exist in her,” said Dr. Khoruts. “She was colonized by all sorts of misfits.” Two weeks after the transplant, the scientists analyzed the microbes again. Her husband’s microbes had taken over. “That community was able to function and cure her disease in a matter of days,” said Janet Jansson, a microbial ecologist at Lawrence Berkeley National Laboratory and a co-author of the paper. “I didn’t expect it to work. The project blew me away.” Scientists are regularly blown away by the complexity, power, and sheer number of microbes that live in our bodies. “We have over 10 times more microbes than human cells in our bodies,” said George Weinstock of Washington University in St. Louis. But the microbiome, as it’s known, remains mostly a mystery. “It’s as if we have these other organs, and yet these are parts of our bodies we know nothing about.”
Patrick House: Landon Donovan Needs a Cat
Could rates of Toxo infection predict soccer success? If we set aside the qualifying rounds (in which teams can play to a draw) and focus on matches with a clear winner, the results are very compelling. In the knockout round of this year’s tournament, eight out of eight winners so far have been the teams whose countries had higher rates of Toxo infection. If we go back to the 2006 World Cup, seven out of eight knockout-round winners could be predicted by higher Toxo rates. The one exception to the rule was Brazil’s defeat of Ghana, a match between two nations that each have very high rates. (Aside from having the winningest team in World Cup history, Brazil has quite a few cases of Toxo: Two out of three Brazilians are infected.) It gets better. Rank the top 25 FIFA team countries by Toxo rate and you get, in order from the top: Brazil (67 percent), Argentina (52 percent), France (45 percent), Spain (44 percent), and Germany (43 percent). Collectively, these are the teams responsible for eight of the last 10 World Cup overall winners. Spain, the only one of the group never to have won a cup, is no subpar outlier—the Spaniards have the most World Cup victories of any perpetual runner-up. What is going on here? Does Toxo really make people better at soccer?
The Economist: A Game of Cat and Mouse
Toxoplasma gondii is not an alien; it is a relative of that down-to-earth pathogen Plasmodium, the beast that causes malaria. It is common: in some parts of the world as much as 60% of the population is infected with it. And it can harm fetuses and people with AIDS, because in each case their immune systems cannot cope with it. For other people, though, the symptoms are usually no worse than a mild dose of flu. Not much for them to worry about, then. Except that there is a growing body of evidence that some of those people have their behaviour permanently changed. One reason to suspect this is that a country’s level of Toxoplasma infection seems to be related to the level of neuroticism displayed by its population. Another is that those infected seem to have poor reaction times and are more likely to be involved in road accidents. A third is that they have short attention spans and little interest in seeking out novelty. A fourth, possibly the most worrying, is that those who suffer from schizophrenia are more likely than those who do not to have been exposed to Toxoplasma.
American Society for Microbiology: Can Bacteria Make You Smarter?
“Mycobacterium vaccae is a natural soil bacterium which people likely ingest or breath in when they spend time in nature,” says Dorothy Matthews of The Sage Colleges in Troy, New York, who conducted the research with her colleague Susan Jenks. Previous research studies on M. vaccae showed that heat-killed bacteria injected into mice stimulated growth of some neurons in the brain that resulted in increased levels of serotonin and decreased anxiety. “Since serotonin plays a role in learning we wondered if live M. vaccae could improve learning in mice,” says Matthews. Matthews and Jenks fed live bacteria to mice and assessed their ability to navigate a maze compared to control mice that were not fed the bacteria. “We found that mice that were fed live M. vaccae navigated the maze twice as fast and with less demonstrated anxiety behaviors as control mice,” says Matthews.
Tina Hesman Saey: Human Genome Is Part Bornavirus
Bornaviruses, a type of RNA virus that causes disease in horses and sheep, first inserted their genetic material into ancestral human DNA at least 40 million years ago, the study shows. The findings, published January 7 in Nature, provide the first evidence that RNA viruses other than retroviruses (such as HIV) can stably integrate genes into host DNA. The new work may help reveal more about the evolution of RNA viruses as well as their mammalian hosts.“Our whole notion of ourselves as a species is slightly misconceived,” says Robert Gifford, a paleovirologist at the Aaron Diamond AIDS Research Center, affiliated with Rockefeller University in New York City. Human DNA includes genetic contributions from bacteria and other organisms, and humans have even come to rely on some of these genes for basic functions like fighting infections.
Brian Merchant: Tropical Plant Uses ‘Mind Control’ Chemical to Make Ants Do Its Bidding
New research reveals that the acacia plant actually produces a chemical that drives the ants into a defensive frenzy–alternately persuading them to fight to protect it and banishing them from its flowers when convenient.
Science Daily: New Disease Among HIV-Infected Gay Men
A rare parasitic disease, which normally only is transmitted by contaminated water, has been shown to be transmitted by gay sex between hiv-positive men. In the industrial world the disease is virtually absent, but that could change. [...] Amebiasis, an infection with the single-celled amoeba Entamoebia histolytica, normally is very rare. You only catch it in a few developing countries where the amoeba is endemic, and where hygiene is somewhat substandard, leading to contact with contaminated water. It only becomes dangerous when the amoeba invades your intestinal lining and causes a bloody diarrhoea, or when it enters the bloodstream, where it, among other things, causes liver abscesses. All in all amebiasis takes some 70 000 lives a year, worldwide. [...] In Taiwan, seropositive (hiv-infected) gay men were shown to be infected much more often with the amoeba than the healthy population, and also than seropositive heterosexuals. Also, Hung found men from different regions nevertheless to be infected by closely related amoebas. The most reasonable explanation is that the infection happened through homosexual (oral-anal) contact.
