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African trypanosomiasis, or sleeping sickness, is caused by the protozoan Trypanosoma brucei, a single-celled eukaryote. Being eukaryotic, it has a cell nucleus and a larger genome than most bacteria; it also has a flagellum with which it can propel itself. Infection with T. brucei occurs via the bite of a blood-sucking fly, one of several species of ...


40

The phrase "Breast is best" is a hotly debated one (source: The Guardian and personal communications with many folks). The reason why we don't want to feed infants cow's milk is, however, anything but debated, because Cow's milk does not provide enough: Vitamin E Iron Essential fatty acids And because it contains too much: Protein Sodium Potassium (...


36

Long lasting immunity is obtained by means of the adaptive immune system, and mainly involves the development of antibodies that identify specific parts (epitopes) of the pathogen's proteins. Common cold is typically caused by a type of virus called rhinovirus. Viruses have very high mutation rates, which alter the sequence of the virus proteins, modifying ...


25

Short Answer: Fever cannot cure Ebola simply because the virus is not temperature-sensitive. Background: Fever is a defense mechanism of the body which is specific to temperature-sensitive virus and bacteria. It is so because high temperature induces stronger immune response and makes the body hostile for the pathogen1. Ebola virus, on the other hand, is ...


24

The flu virus changes rapidly so that the current vaccine doesn't work against the new strains. The way vaccines work is that they teach our immune system what to look out for. The vaccine contains bits of the virus but in a form that can't cause a proper infection, the body learns what to look for and next time before the virus can really get going the ...


24

First, I want to note that ddiez has a good answer, but I thought this was good question to have a more expanded answer on immunology and pathogenesis. The First thing we need to establish what is a "cold". The most common cold is rhinovirus (HRV), but the second place holder is a little harder to define. For example, respiratory syncytial virus (RSV) ...


21

According to the Wikipedia entry for the ABO blood group system: Anti-A antibodies are hypothesized to originate from immune response towards influenza virus, whose epitopes are similar enough to the α-D-N-galactosamine on the A glycoprotein to be able to elicit a cross-reaction. Anti-B antibodies are hypothesized to originate from antibodies produced ...


21

Doctors would recommend the use of barrier protection for couples where both partners are HIV+ because the virus can mutate. Mutated forms of the virus can become resistant to Highly Active Antiretroviral Therapy (HAART) treatments, rendering them ineffective. The use of barrier protection reduces the risk that a resistant mutant strain of HIV is ...


19

Personal comfort is the primary answer. Quite a bit of research has gone into fevers, and the current consensus is that Fevers less than 105F (40.5C) shouldn't necessarily be treated. The primary reason the body raises its temperature (via the Hypothalamus in this case) is that bacteria and viruses tend to optimally thrive at 98.6F, which is also your body'...


19

Most information here can be found broadly in Cellular and Molecular Immunology, 8th Ed. Here's how the flu vaccine works: Scientists forecast months in advance which strains they think stand to cause the most problems. The vaccine is often trivalent, protecting against three different strains on flu: Two influenza A and one influenza B. You can read about ...


18

So while some kind of a biological database might have been an evolutionary option, the way we evolved is different from this. Rather than 'planning' what diseases could be recognized in the environment and recording this, our bone marrow constantly pumps out naive B and T cells that have a randomized receptor on them. The effect of this is that every new B ...


18

The reasons why HIV is "incurable" (a misnomer) are legion: HIV is a retrovirus, which means it inserts its own genome into the host cell's genome. You must therefore kill each and every infected cell to rid the body of the virus. HIV is a lentivirus, which means it has a long incubation period, so it can "lay low" before symptoms are readily detected. HIV ...


17

The goal of the vaccine is to provoke an immune response, therefore some degree of inflammation is expected in order for the vaccine to work. As swbarnes2 says, vaccines contain adjuvants, pro-inflammatory molecules that produces local inflammation and recruits immune cells to the site of the inoculation. Since you get the shot intramuscularily, ...


17

I think no one can really deny the existence of HIV or AIDS, just a search on google scholar will show >1,500,000 hits for each of those terms, and ask (hopefully any) doctor and they will say it does, though AIDS denialists do debate whether HIV causes AIDS. This paper explains the process of HIV causing AIDS. Further, AIDS denialists have not offered up ...


17

Our immune system does react to horse antibodies, but as with any adaptive immune response it takes some time for the response to develop. In the weeks before our immune response fully responds to the horse antibodies, the infused antibodies can have their effect. If you then have a second infusion of horse antibodies, the immune response would not only ...


17

While the data are much too sparse and noisy to give an answer about what is happening to COVID-19's virulence (the technical term for the "deadliness" of an infectious disease), or to forecast what will happen to its virulence in the future, there are indeed theoretical reasons that one might expect the virulence to decline in the future. There is an ...


16

Good question! Let's start with an overview and explanation of the ABO blood grouping system (Dean, 2005): Blood groups, antigens and antibodies: Subjects with blood group A carry the A antigen on their red blood cells (RBCs) and have antibodies to antigen B; subjects with blood group B have the B antigen and anti-A antibodies, blood group AB carries both ...


16

It's common for the reservoir host of a zoonotic virus to be tolerant of it. MERS coronavirus appears to cause mild or no disease in dromedary camels ( source ), but kills about 35% of confirmed infected humans. ( CDC ) Sin Nombre hantavirus seems to be mild in the deer mice that spread it, despite ~36% fatality rate in humans. ( source ) Mosquitoes are ...


15

In the graph above the darker blue line refers to the antibodies the baby receives from the mother in utero, as you mentioned in your question. As you can see, the red line indicates that babies begin to produce low levels of their own antibodies between 3 and 6 months before birth. However, these are IgM antibodies, immature 'rough draft' versions. ...


15

With AIDS, the whole immune system is not non-functional. The condition results in a severe drop in CD4+ T-cells, which is what primarily predisposes AIDS patients to secondary infections. Fever can be an immune response to infection, but it is not directly affected by the loss of CD4+ T-cells. Rather, fever occurs due to a complex cascade of events ...


14

The important thing to recognize about the host response to sepsis is that it is actually a generalization of mechanisms used in local infection response by the innate immune system. When an animal has a local infection, such as at a wound site, innate immune cells such as monocytes and macrophages recognize 'generic' bacterial features, such as ...


14

Rabies virus enters the body, typically from a bite, and then enters nerves which it follows up to the brain. An immune response to a first exposure of a pathogen generally takes many days, perhaps weeks, to develop to the point where it's protective. This is often even slower when the pathogen is in nerves, which are relatively sheltered from the immune ...


13

Many of the symptoms of disease are indeed related to inflammation, but inflammation depends heavily (though not solely) on the innate immune response. Patients with AIDS and some of the other immunodeficiencies lose their adaptive immune response, not their innate response. Therefore they are capable of mounting an inflammatory response that is not ...


13

At one of my previous companies that raised antibodies to proteins and post-translational modifications, we found that 6-8 amino acids was generally the smallest peptide length required for an epitope. Anything much smaller than that won't induce the cross-linking or conformational changes required for signal transduction and an allergic response. As WYSIWYG ...


13

There are multiple challenges presented, and many of those are not limited to coronavirus vaccine. As mentioned above, it just takes time. Before a vaccine can be used in patients, clinical trials must be performed to validate the safety and efficiency of the vaccine candidate. A Clinical trial includes three phases, which again, just takes time. But to ...


12

I think the current answer to this for bacterial infections is quorum sensing. Quorum sensing is a signalling pathway in bacteria which senses a molecule that the bacteria themselves secrete. When the concentration of the quorum signal reaches a certain level, the bacteria interpret this as their population density reaching some threshhold. Bacteria are ...


12

Small molecules do not have antigenic properties but they can elicit immune response by binding to a "carrier" protein. The small molecule is called a Hapten. An epitope forms at the protein-hapten binding interface. Nickel acts like a hapten and elicits immune response by binding to proteins like transferrin, albumin etc. Other metals also cause ...


12

The combination of these two reports from the CDC give information about the comparative prevalence of flu infection in the winter (September '12- May '13) and summer (May '13 - September '13). I'm going to assume that 2012-2013 was a fairly representative year as far as the level of detail of "do we get sick more in the winter" goes. Particularly striking ...


12

Nothing. Rhesus incompatibility results when people who are Rh- develop antibodies against Rh+ blood after exposure. People with Rh+ blood do not show any such reaction to Rh- blood. In a way, it's comparable to blood types in that regard. People with the blood group O can develop antibodies against type (for example) B blood. People with type B don't ...


12

You are not totally correct because these two strands don't have to be the same, they can be genotypically different, which occurs when a cell is infected by two distinct HIV strains. Also HIV uses reverse transcriptase which can "jump" from one strand to the other so sometimes pieces get repeated, skipped etc. So you will get a recombinant --> more genetic ...


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