31

I can think of several (non-exclusive and probably non-exhaustive) hypotheses: Maladaptive. It is maladaptive. Maybe because it is a virus coming from another species (e.g. SIV and HIV) or because it is not adapted to our modern lifespan. Benefit of the host immune system to the parasite. Some parasites might benefit from host immune defence (e.g. sneezing ...


19

There is a genetic component to mosquito's attraction to humans. Female mosquitoes display preferences for certain individuals over others, which is determined by differences in volatile chemicals produced by the human body and detected by mosquitoes. ... Overall, there was a strong narrow-sense heritability of 0.62 (SE 0.124) for relative attraction and ...


13

First part of the answer - Yes fleas (Siphonaptera) can be drowned. But not as easily as the internet would lead you to believe. There are many claims on the internet (and printed works) expounding on how simple it is to drown fleas. The best science I found so far on the topic is in Forensic Entomology: An Introduction By Dorothy Gennard; John Wiley & ...


12

Short answer T. solium infection can be identified in pork meat by visual inspection. Background The stage of the life cycle of the tape worm T. solium in pigs is characterized by cysticerci, which is the larval stage consisting of a protoscolex (head) of the tapeworm. Humans are the definitive host, which means they are the species in which the parasite ...


11

Short answer There is no evidence whatsoever that the parasitic arthropod Cymothoa exigua develops itself into a functional tongue. Instead, it consumes the fish's tongue and occupies the freed buccal space to continue feeding onto the fish's blood or mucus. Background The linked wikipedia page that states that Cymothoa exigua arthropods form fully ...


10

Some parasites aren't natural hosts of humans, instead we are an accidental host in which they cannot replicate. Zoonoses such as this can be quite fatal as the parasite is not adapted to us. Although viruses are often separated, they are parasites and you can see just in influenza that the animal derived flus are more fatal than those that are well adapted ...


10

Plasmodium falciparum (the main causative agent of malaria) and other Plasmodium species have a very complex life cycle, with stages in the female host Anopheles mosquito, in the human liver, and in the human circulatory system, where it primarily resides in the erythrocytes (red blood cells, or RBCs): During a blood meal, a malaria-infected mosquito ...


9

The diversity of parasites shows a gradient with increasing diversity from the poles to the equator. Several reasons have been brought forth to explain the latitude-dependency of parasite diversity: An increased diversity overall around the equator; species diversity in general is greater in the rain forests and hence more hosts are available and thus more ...


9

It is Giant Stomach Worm (Hirudinella Ventricosa). It is a platyhelmith parasitic to Wahoo fish, feeding on its blood and found inside the stomach. It makes 98% of Wahoo's parasitic infections. It is a fleshy worm that varies in size and shape; with extended worms the size of a mans finger and contracted ones about the size of a walnut. It requires ...


8

Yes it is possible to culture plasmodia but they don't grow in a simple constituted medium. Usually RPMI supplemented with serum and erythrocytes is used for growing plasmodia ex-vivo. This article discusses the issues related to plasmodial culture in detail. The authors say that sometimes a certain growth stage (in particular gametocyte) is lost on ...


8

This is a really old thread but just in case someone happens upon it, this isn't a bed bug. I am not an expert but it looks like it's likely a book louse or psocid. See comparison photos of unfed first instar bed bug nymphs vs. psocids/booklice here: http://bedbugger.com/2008/03/04/booklice/ It's all about the shape of the head and body.


8

This is related to Remi.b's answer, but a common reason is that sometimes parasites/pathogens actually need to kill the host to spread. A lot of viruses, in particular phages, are only released from their host by bursting out of the cell. If the parasite can't leave the host, there's no point in any of it, and death may be a good way to achieve that. A ...


8

Female mosquitoes need blood for laying their eggs. This actually means that they need a source of rich protein and iron for their kids and hence, prey on us. It is worthwhile for us to pause here and ponder over the difference between clumping and clotting before proceeding to the actual answer. Agglutination tests as you may have come across are ...


6

Is consumption of blood more "dangerous" compared to meat? Actually yes, a simple high dose of blood is enough to kill. The cause is, though it is most important thing to live when flowing the vessel, it's highly toxic when consumed. There are high chances of getting haemochromatosis or Iron overload. Source and More on this: http://www.livescience.com/...


6

With humans infected with malaria, the parasite load in the blood can be quite high. It ranges from 10 to 108 Plasmodium falciparum parasites per ml . When a female Anopheles mosquito bites an infected human, they take in infected blood, not just the parasite. They take in a few micro liters of blood, which in usually enough to get themselves infected, and ...


6

There are many examples of parasite manipulation in nature, if you want more examples you can look up the paper of Lefevre and Thomas (2008). I think the key is, in order for a parasite to develop such behaviour, that it should be giving them a fitness advantage. So I don't think it would ever happen for no reason. The paper discusses a few examples where ...


5

The fungus releases toxins, but how exactly this alters behavior is unclear. You can read more here. Pathogen manipulation of host behavior appears to have evolved a long time ago, and cordyceps is not the only pathogen that acts like this.


5

The species of wasp you're referring to is Glyptapanteles. I'm not sure which virus it is. http://www.newscientist.com/article/dn14053-zombie-caterpillars-controlled-by-voodoo-wasps.html?feedId=online-news_rss20 Is it possible? Of course, you have an example! Though, there is a small caveat. Some of the offspring sacrifice themselves to induce the ...


5

You're right in saying that yeast is single celled. However, moulds are described to be filamentous fungi that are multicellular. The filaments of the mould give colonies "a woolly, fluffy, or velvety appearance, sometimes punctuated with a granular or powdery aspect that is produced by the formation of asexual reproductive structures"(1). Aspergillus is ...


5

A reservoir host most obviously is a long-term carrier organism of a given pathogen that doesn't exhibit the disease caused by the pathogen. A vector is literally any agent that transfers the pathogen to another organism. If you think about it, a reservoir doesn't have to be a vector i.e. there's no route of transmission they participate in, but a vector ...


5

Okay, I found the last part of your question the most interesting and can't give a full answer to that, but I just noticed I can answer the rest so here goes. How it works (the simple version) It works on the principles of buoyancy. The eggs and oocysts are less dense (lighter) than the fecal flotation solution and, consequently, they float on the very ...


4

If you have or can get access to it, you might try looking in the Incidence and Prevalence database: http://thomsonreuters.com/incidence-and-prevalence-database/ Another possibility is the GIDEON database: http://www.gideononline.com/. It is possible to sign up for a 15-day trial. For Europe, statistics are available from the WHO CISID at http://data.euro....


4

Based on my course material, I managed to get the following list: Malaria - Plasmodium falciparum, p. malariae, p. vivax, p. ovale - female anopheline mosquito Babesiosis - Babesia devergens, babesia microti - tick ixodes ricinus Balantidiasis - Balantidium coli - waterborne Coccidiosis & toxoplasmosis - Eimeria species - waterborne Toxoplasmosis - ...


4

As Armatus pointed out above, all viruses are obligately intracellular, and their medical and economic importance cannot be overstated. Many bacterial species live intracellularly. The arthropod specific Wolbachia has a wide variety of consequences for its host, including alteration of reproduction and sex ratios, induction of reproductive isolation ...


4

Do not forget domesticated animals that we now keep as pets. It's not unreasonable to argue that the relationship between dogs/cats and humans has a symbiotic character. The pet gets foodand shelter whereas the owner benefits in other ways, e.g. companionship, deterrence of enemies, herding,...


4

Here are some examples: symbiosis between genetic modified yeast cell populations (Shou W et al. 2007) symbiosis between green algae and embryonic chick connective tissue (Buchsbaum R et al. 1934) symbiosis between EcoBot II and microbial fuel cells (Ieropoulos, Ioannis, et al. 2005)


4

A very basic model of virus inactivation is exponential decay. You can describe exponential decay with the $N(t) = N_0e^{-\lambda t}$ equation, of if you want to use half-time, then with the $N(t) = N_02^{-t/t_{1/2}}$, where $N$ is the value which reduces by time, $t$ is the time, $\lambda$ is the exponential decay constant and $t_{1/2}$ is the half-life (...


4

It is a well documented observation that Plasmodium (vivax and knowlesi) infection is dependent on the Duffy blood groups [1]. Individuals lacking the Duffy antigens (Fya and Fyb) have lower susceptibility to malaria. Plasmodium expressed Duffy Binding Proteins facilitate in establishing the initial contact between the merozoite and the RBCs. However, ...


4

Just to add to Christiaan's excellent answer: The authors of his cited study state: [the tongues] replacement by a parasite would not appear to be a complex phenomenon. Implying that this is a very basic process, according to what they observed. To answer your question as it was posed: Wikipedia states the tongue becomes fully functional. The authors ...


4

If there are drugs that can cause this kind of disorder you described, then it is possible to engineer a microbe, that can produce these drugs and maintain a chronic infection, which does not necessarily kills the host. Walking dead is not possible, human bodies cannot move with rotting muscles or without muscles, so you won't see real zombies, just insane ...


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