Post Reply 
Manipulative Parasites and their methods..
10.08.2013, 15:42
Post: #1
Manipulative Parasites and their methods..
Suicide Grasshoppers Brainwashed by Parasite Worms

Loxdale hadn't previously heard of a parasite that drives an insect to suicide. But he draws parallels with a fungus that attacks hoverflies (stingless flies that resemble honeybees.)

"The hoverflies very conveniently die on the top of grass stems, which maybe makes the transmission of fungal spores easier," he said. "The spores penetrate the insect cuticle [skin] then grow inside the insect and quickly kill it."

Hairworms, or Nematomorpha, are a little-known group of parasites, which contains around 300 known species worldwide. Biron, the study author, says the organisms target a wide range of land-based insects, including praying mantises.

The French research team studied proteins produced by both the parasite and its host to investigate how hairworms might make grasshoppers hop to their deaths.

Central Nervous System

The team found that hairworms release proteins that influence grasshoppers' central nervous systems, thereby affecting chemical signals to the insects' brains.

"Some of these proteins secreted by the worm [mimic] proteins produced by the grasshopper," Biron added.

This biochemical tampering appears to drive the grasshopper to water just when the hairworm is ready to reproduce.

Study co-author Frédéric Thomas says other parasites may use a similar strategy to manipulate their hosts.

For example, a type of parasitic flatworm targets cockles in New Zealand, driving the marine mollusks to the surfaces of muddy bottoms in shallow waters. There, oystercatcher birds snap the cockles up and eat them, flatworms and all. The shorebirds serve as the final hosts in the flatworms' complex life cycle.

"Parasitic wasps can also make the host weave a special cocoon-like structure to protect the wasp pupae [offspring] against heavy rain," Thomas added.

While revelations about the hairworm's antics may inspire a new generation of sci-fi aliens, the study team says their findings may also help the development of new medical treatments.

Biron says mind-altering human pathogens—such as those that cause rabies, sleeping sickness, and toxoplasmosis—may manipulate their victim in similar ways.

He said further understanding of biochemical communication between a parasite and its host may "ultimately assist researchers in the search for new drugs and vaccines." .. read more:

Parasites Affecting Insect Behaviour

Parasites need to have adaptations for colonisation, defeating immune systems and transmission. Often, parasitism involves very complex interactions between not-so-closely-related organisms. For example, the jungle-dwelling turtle ant above is infected by nematodes that gather and mate in the gaster (hind part of the ant). They deteriorate the cuticle of the gaster (turning it red), as well as the petiole joint (which joins the gaster to the rest of the ant). Not only that, they somehow mess around with the ant’s brain, making it stay on top of trees and wave its gaster around. The only reason for this is to make the ant’s gaster attractive to birds: they look like fruit and are swinging around, asking to be eaten; the nematodes need the birds to complete their life cycle.

Parasitism can be seen as a form of symbiosis, when symbiosis is viewed as a continuum. At the one end, you have obligate symbiotic relationships such as bacteria living in a cow’s stomach. On the other end, you have pathogenic parasites that infect and kill their hosts in order to eat their corpses. However, there are no sharp lines dividing these categories; it’s more of a gradient. As an example, consider scale insects. They live in colonies endemically on plant leaves (some may see them as plant parasites). A few individuals can get infected by the fungus Septobasidium, which kills those individuals and builds a whole coccoon over the leaf, trapping the insects inside. However, this is perfect (for everyone but the plant): the insects are guaranteed reproductive success and protection from other pathogens, while the fungus gets a free source of food. It’s both symbiotic in the way the scale insects and the fungus cooperate, but the way this cooperation starts is parasitic.

Some advantageous symbionts may turn pathogenic under certain conditions – this is one of the models for the evolution of parasitism. The degree of adaptation and specialisation that parasites have indicates that they must have been in a close relationship with their hosts, as symbiotic organisms. Other times, the parasite doesn’t affect its host and only uses it as a vector (mosquitoes and Plasmodium, for example). The fact that many hosts and vectors have special compartments for their parasites, especially if they are beneficial, is also a strong indication that regular symbiosis was at the start of a parasitic relationship.

read more.. source:

Manipulative Microbes
The invisible invaders that influence guts, brains, and decision making
by Teresa Lee
We all know how complicated our behavior can be. Despite many psychiatric and biological advances in the past century, humans have never completely understood how external or internal forces influence our behavior—our upbringing, diet, parents, and genes have all been implicated in making us do what we do. Recent studies into the millions of microbes that share our bodies may add several (thousand) more culprits to the list. And even though microbes live inside us animals, only some of them are on our side.
Perfectly tailored

Take the aberrant behavior of an infected ant in the Thai jungle. Normally, a worker ant forages for materials along chemically-determined trails in its colony’s territory. But when spores of the Cordyceps fungus infiltrate an ant’s exoskeleton, the fungus begins to take root, feeding on the ant’s nonessential organs. After a few days, Cordyceps filaments will have grown into the ant’s brain, driving the ant to commit its last act. It will stagger from its nest, climb a nearby shrub, and clamp its mandibles onto a leaf’s vein.

read more .. source:

Alteration of host behaviour

doi: 10.1242/​jeb.074088 January 1, 2013 J Exp Biol 216, 11-17.
An overview of parasite-induced behavioral alterations – and some lessons from bats

Janice Moore

+ Author Affiliations

Department of Biology, Colorado State University, Fort Collins, CO 80523, USA


An animal with a parasite is not likely to behave like a similar animal without that parasite. This is a simple enough concept, one that is now widely recognized as true, but if we move beyond that statement, the light that it casts on behavior fades quickly: the world of parasites, hosts and behavior is shadowy, and boundaries are ill-defined. For instance, at first glance, the growing list of altered behaviors tells us very little about how those alterations happen, much less how they evolved. Some cases of parasite-induced behavioral change are truly manipulative, with the parasite standing to benefit from the changed behavior. In other cases, the altered behavior has an almost curative, if not prophylactic, effect; in those cases, the host benefits. This paper will provide an overview of the conflicting (and coinciding) demands on parasite and host, using examples from a wide range of taxa and posing questions for the future. In particular, what does the larger world of animal behavior tell us about how to go about seeking insights – or at least, what not to do? By asking questions about the sensory–perceptual world of hosts, we can identify those associations that hold the greatest promise for neuroethological studies of parasite-induced behavioral alterations, and those studies can, in turn, help guide our understanding of how parasite-induced alterations evolved, and how they are maintained.
read more.. source:

Toxo Terror: Are Our Brains Controlled by Cat-Loving Parasites?

By Greg Boustead

Read more:
Follow us: @motherboard on Twitter | motherboardtv on Facebook

The sheer ubiquity of microscopic organisms is staggering. Microbiologist Tom Curtis recently compared the size of the microbial population to the size of the universe: The number of microbes in the world is billions of times larger than the number of stars in the sky. Think about that for a second.

And welcome back. Teeming within your body alone are trillions of microorganisms—bacteria, fungi, viruses, protists—that make up 90 percent of all the cells in your body. You are more them, than you are you. In fact, there’s not really a you. Your body is more of an ecosystem than a discrete organism. The sum effect of this fact is unnerving: In a way, you are not one thing, but a codependent mass of countless organisms, moving in unison toward shared goals. Through hundreds of thousands of years of co-evolution within this host-microbe habitat, these organisms have developed a complex scheme of cat-and-mouse survival strategies that affect the overall system.

So then: Whenever you do something, whenever you make one of the myriad, inane daily choices that ultimately define who you are, who is it making the decision? You? Or is it them?

The idea that microscopic flora living inside our bodies can directly manipulate our behavior and personality is perhaps surprising. It’s also exactly what a growing number of scientists is suggesting. And it’s absolutely terrifying.

For the past few decades, an obscure scientist in Prague, Jaroslav Flegr, has been studying the influence of a particular brain parasite that co-opts the behavior of its hosts in surprising ways. The goal of this parasite, a protozoan known as Toxoplasma gondii, is simple: It wants whatever host it’s infected (typically a rodent) to get eaten by a cat.

Why? Because Toxoplasma can only reproduce in the digestive tracts of cats. So it’s devised a clever strategy: The parasite alters signals in the rodent’s brain, making it behave in ways that increase the possibility it will be caught and eaten by a cat— namely by removing the rodent’s instinctual fear of cats, slowing its reaction time, and actually making it attracted to the smell of cat urine.

“It’s the most damn amazing thing you can ever see,” said Robert Sapolsky, a neurobiologist at Stanford University, in an interview with “Toxo knows how to make cat urine smell attractive to rats. And rats go and check it out and that rat is now much more likely to wind up in the cat’s stomach. Toxo’s circle of life completed.”

Read more:
Follow us: @motherboard on Twitter | motherboardtv on Facebook


Is your cat making you crazy? Feline parasite 'can cause schizophrenia in humans'

Toxoplasma microbe 'takes over' the human brain
A person will become less risk-averse
Part of 'circle of life' for parasite

By Charles Walford
UPDATED: 16:41 GMT, 10 February 2012

Read more:
Follow us: @MailOnline on Twitter | DailyMail on Facebook
Parasites passed from cats could be causing schizophrenia in their owners, a scientist has claimed.

Jaroslav Flegr says has come to the conclusion because he himself believes he is a living example.

He says he has been infected by the parasite and it has altered his behaviour over a period of time.

The parasite, which is excreted by cats in their feces, is called Toxoplasma gondii and is the microbe that causes toxoplasmosis - the reason pregnant women are told to avoid cats’ litter boxes.

Since the 1920s, doctors have recognised that a woman who becomes infected during pregnancy can transmit the disease to the foetus, resulting in severe brain damage in the baby - or even death.

In adults the diesease causes flu-like symptoms - and those with a suppressed immune system can become seriously ill with complications such as encephalitis (inflammation of the brain) - but many carrying the latent disease and appear to have no symptoms.

However, once inside an animal or human host, the parasite then needs to get back into the cat, as that is the only place where it can sexually reproduce.

Read more:
Follow us: @MailOnline on Twitter | DailyMail on Facebook

The demon within

Candida albicans. Some strains have adapted to sexual transmission. Have they gone so far as to manipulate host behavior?

Vulvovaginal candidiasis (VVC), commonly known as vaginal yeast infection, affects 70-75% of sexually active women at least once and 5-8% recurrently (Li et al., 2008). It is usually caused by Candida albicans, a single-celled fungus that reproduces asexually.

Although C. albicans can colonize many body sites, some strains have specifically adapted to the vagina. This evolutionary trajectory seems to have gone through three levels of adaptation:

Adaptation to vaginal environments

Vaginally adapted strains are a small subset of C. albicans. In China, two strains account for almost 60% of all VVC cases, yet neither is present at extragenital sites (Li et al., 2008). In the United States, C. albicans strains are much more diverse in the male partners of women without VVC than in the vaginas of women with or without VVC (Schmid et al., 1993).

Adaptation to sexual transmission

These vaginal strains seem to have also adapted to sexual transmission, specifically female-to-male transmission. Once VVC develops, they can spread to the host’s male partner by colonizing his glans penis via vaginal intercourse (Li et al., 2008) or his oral cavity via cunnilingus (Schmid et al., 1995). Vagina-to-vagina transmission has also been attested in lesbian couples (Bailey et al., 2008).

There is evidence of genetic changes for sexual transmissibility. Vaginal strains adhere better to saliva-coated surfaces than do other strains (Schmid et al., 1995). In the male partner, they tend to displace non-vaginal strains of C. albicans (Schmid et al., 1993).

Adaptation to certain sexual behaviors
read more..source:

Human Microbiota in Health and Disease
by de Vos WM, Engstrand L, Drago L, Reid G, Schauber J, Hay R, Mendling W, Schaller M, Spiller R, Gahan CG, Rowland I.

Each human body plays host to a microbial population which is both numerically vast (at around 1014 microbial cells) and phenomenally diverse (over 1,000 species). The majority of the microbial species in the gut have not been cultured but the application of culture-independent approaches for high throughput diversity and functionality analysis has allowed characterisation of the diverse microbial phylotypes present in health and disease.

Studies in monozygotic twins, showing that these retain highly similar microbiota decades after birth and initial colonisation, are strongly indicative that diversity of the microbiome is host-specific and affected by the genotype. Microbial diversity in the human body is reflected in both richness and evenness. Diversity increases steeply from birth reaching its highest point in early adulthood, before declining in older age. However, in healthy subjects there appears to be a core of microbial phylotypes which remains relatively stable over time.

Studies of individuals from diverse geopraphies suggest that clusters of intestinal bacterial groups tend to occur together, constituting ‘enterotypes’. So variation in intestinal microbiota is stratified rather than continuous and there may be a limited number of host/microbial states which respond differently to environmental influences. Exploration of enterotypes and functional groups may provide biomarkers for disease and insights into the potential for new treatments based on manipulation of the microbiome.

In health, the microbiota interact with host defences and exist in harmonious homeostasis which can then be disturbed by invading organisms or when ‘carpet bombing’ by antibiotics occurs. In a portion of individuals with infections, the disease will resolve itself without the need for antibiotics and microbial homeostasis with the host’s defences is restored. The administration of probiotics (live microorganisms which when administered in adequate amounts confer a health benefit on the host) represents an artificial way to enhance or stimulate these natural processes.

The study of innate mechanisms of antimicrobial defence on the skin, including the production of numerous antimicrobial peptides (AMPs), has shown an important role for skin commensal organisms. These organisms may produce AMPs, and also amplify the innate immune responses to pathogens by activating signalling pathways and processing host produced AMPs. Research continues into how to enhance and manipulate the role of commensal organisms on the skin. The challenges of skin infection (including diseases caused by multiply resistant organisms) and infestations remain considerable. The potential to re-colonise the skin to replace or reduce pathogens, and exploring the relationship between microbiota elsewhere and skin diseases are among a growing list of research targets.

Lactobacillus species are among the best known ‘beneficial’ bacterial members of the human microbiota. Of the approximately 120 species known, about 15 are known to occur in the human vagina. These organisms have multiple properties, including the production of lactic acid, hydrogen peroxide and bacteriocins, which render the vagina inhospitable to potential pathogens. Depletion of the of the normal Lactobacillus population and overgrowth of vaginal anaerobes, accompanied by the loss of normal vaginal acidity can lead to bacterial vaginosis – the commonest cause of abnormal vaginal discharge in women. Some vaginal anaerobes are associated with the formation of vaginal biofilms which serve to act as a reservoir of organisms which persists after standard antibiotic therapy of bacterial vaginosis and may help to account for the characteristically high relapse rate in the condition. Administration of Lactobacillus species both vaginally and orally have shown beneficial effects in the treatment of bacterial vaginosis and such treatments have an excellent overall safety record.

Candida albicans is a frequent coloniser of human skin and mucosal membranes, and is a normal part of the microbiota in the mouth, gut and vagina. Nevertheless Candida albicans is the most common fungal pathogen worldwide and is a leading cause of serious and often fatal nosocomial infections. What turns this organism from a commensal to a pathogen is a combination of increasing virulence in the organism and predisposing host factors that compromise immunity. There has been considerable research into the use of probiotic Lactobacillus spp. in vaginal candidiasis. Studies in reconstituted human epithelium and monolayer cell cultures have shown that L. rhamnosus GG can protect mucosa from damage caused by Candida albicans, and enhance the immune responses of mucosal surfaces. Such findings offer the promise that the use of such probiotic bacteria could provide new options for antifungal therapy.

Studies of changes of the human intestinal microbiota in health and disease are complicated by its size and diversity. The Alimentary Pharmabiotic Centre in Cork (Republic of Ireland) has the mission to ‘mine microbes for mankind’ and its work illustrates the potential benefits of understanding the gut microbiota. Work undertaken at the centre includes: mapping changes in the microbiota with age; studies of the interaction between the microbiota and the gut; potential interactions between the gut microbiota and the central nervous system; the potential for probiotics to act as anti-infectives including through the production of bacteriocins; and the characterisation of interactions between gut microbiota and bile acids which have important roles as signalling molecules and in immunity.

The important disease entity where the role of the gut microbiota appears to be central is the Irritable Bowel Syndrome (IBS). IBS patients show evidence of immune activation, impaired gut barrier function and abnormal gut microbiota. Studies with probiotics have shown that these organisms can exert anti-inflammatory effects in inflammatory bowel disease and may strengthen the gut barrier in IBS of the diarrhoea-predominant type. Formal randomised trials of probiotics in IBS show mixed results with limited benefit for some but not all.

Studies confirm that administered probiotics can survive and temporarily colonise the gut. They can also stimulate the numbers of other lactic acid bacilli in the gut, and reduce the numbers of pathogens. However consuming live organisms is not the only way to influence gut microbiota. Dietary prebiotics are selectively fermented ingredients that can change the composition and/or activity of the gastrointestinal microbiota in beneficial ways. Dietary components that reach the colon, and are available to influence the microbiota include poorly digestible carbohydrates, such as non-starch polysaccharides, resistant starch, non-digestible oligosaccharides (NDOs) and polyphenols. Mixtures of probiotic and prebiotic ingredients that can selectively stimulate growth or activity of health promoting bacteria have been termed ‘synbiotics’. All of these approaches can influence gut microbial ecology, mainly to increase bifidobacteria and lactobacilli, but metagenomic approaches may reveal wider effects. Characterising how these changes produce physiological benefits may enable broader use of these tactics in health and disease in the future.

The current status of probiotic products commercially available worldwide is less than ideal. Prevalent problems include misidentification of ingredient organisms and poor viability of probiotic microorganisms leading to inadequate shelf life. On occasions these problems mean that some commercially available products cannot be considered to meet the definition of a probiotic product. Given the potential benefits of manipulating the human microbiota for beneficial effects, there is a clear need for improved regulation of probiotics.

The potential importance of the human microbiota cannot be overstated. ‘We feed our microbes, they talk to us and we benefit. We just have to understand and then exploit this.’ (Willem de Vos).


Microbiota, probiotic, Lactobacilli, commensals, microbiome, host immunity, bacterial vaginosis, Candida albicans, prebiotics, synbiotics, antimicrobial peptides, bacteriocins, staphyloccocal skin infections, irritable bowel syndrome.

Full Article read more .. source and download:

ons@[Image: buk.jpg]
Visit this user's website Find all posts by this user
Quote this message in a reply
Post Reply 

Forum Jump:

User(s) browsing this thread: 1 Guest(s)

Contact Us | Ethical Fruitarian Archives | Return to Top | Return to Content | Lite (Archive) Mode | RSS Syndication