Hi, this article will help you: http://mmbr.asm.org/content/63/1/128.full

Cheers, Nadine

As i think this retained to host parasite relationship, this question i try to answer it in vector biology workshop , the parasite and the vector together get benefit from this relation , for not all component of the blood meal is nessosory or safety for mosquitoes for it begin to isolate it when it enter for that the residue of the blood meal negative one can be consumed with the parasite also there is differences in cell component between vector and human cells which prevent or facilitate the parasite or virus survival in the two host, this is my theory please let me know if its acceptable theory or not

I couldn't get your answer. Can you please elaborate it ?

I think they get affected to a certain extent.

In most cases of biological/obligatory transmission, there is a mutualstic or a symbiotic relationship of some kind between insect vectors and transmitted pathogens, which usually indicates a long evolutionary relationship. In a few cases however, the pathogen affects the vector negatively but not in a very serious way since in many cases the vector is the only way for pathogen transmission in nature.

I do agree with Dr. Ammar

For the plasmodium: the sporozoites do not come in direct contact of circulatory system of mosquito while in human directly come in contact with circulatory system and then to hypatocytes therefore it does not infect mosquito but humans.

The short answer is that sometimes they do! However, this only tends to happen if it increases the transmission of the pathogen. A pathogen that makes a mosquito "sick" (reduces activity or increases mortality) will generally get transmitted less, so there is strong selective pressure not to do this. However, some behaviours increase pathogen transmission despite making things more dangerous for the vector, like feeding more frequently. Several pathogens (including Plasmodium) are known to affect the behaviour of infected vectors in exactly this way. There's another example in this recent paper: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0063602).

If you're interested in this area, a popular science book called "Parasite Rex" by Carl Zimmer is full of similar examples.

Hi, please find some papers of our group on my publication list concerning the interactions between the Aedes aegypti mosquito and the dengue virus:

Cheers

Rafael

Hi, Mosquitoes do get affected by the parasite; I'm not sure for Dengue, however, with Plasmodium they confer fitness disadvantage to the mosquitoes (many published reports are available). Nonetheless, if virus has to get multiply in the mosquito then it need building blocks and other resources which they draw from mosquito itself (Parasitic relationship). Moreover, either dengue virus or Plasmodium does not have a mutualistic or symbiotic relationship with the mosquito vector.

Secondly, these parasites have evolved to invade the bigger size organisms for their free multiplication. Hence they might have adopted to infect the larger animals which could provide them huge reserves of resources (comparatively to the mosquito). Biology of mosquito and vertebrates are different; hence they choose to invade the vertebrates, larger animals. These parasites take route of mosquito as a carrier which supports their multiplication and further infections.

Third, if they harm mosquitoes then mosquitoes may not live long enough to infect further. So they restrict their damage (evolutionary adaption) to the vector as compared to the ultimate goal, human/bird/animals, etc

Hope this will answer you question!

Niranjan

Host-Parasite relationship is very complex phenomenon.. All anopheline mosquito species are not capable to transmit human malaria. All Aedes species do not transmit dengue virus. All member of a single vector soecies are NOT efficient vector - some kill the pathogen (negative impact on the pathogen), other get killed (negative impact on the vector), while some fully support thr pathoge in a perfect "symbiotic relationship. In an effort to find a 100 % refrectory strain of Culex pipiens-complex to human filariasis, Wuchereria bvancrifti, we found this tricotomy. Molecular genetics may explain "why" and "how" of this evolutionary process.

Its not true that the mosquitoes are not affected by invading pathogen. in case on malaria parasite vectors; the infection by Plasmodium affects the longevity, fecundity and other physiological activities of the mosquitoes. Even i have noticed that heavy infection at midgut (> 400 oocyst) may cause death of the mosquitoes harbouring them. so they are equally affected but with different sign.

look i agree with doctor Ammar and add a thing in which i think when mosquitoes take blood meal the part of blood ,specifically red blood cells with no benefit for the insect, cold blood types, at the same time with high benift for the parasite which supplement it with the suitable cell membrane protiens help it entering the host cell, it just my idea , i need to prove it , and please if you see it logic let me know.

I think Dr El-Desouky Ammar has answer the question quite well

Host=Parasite relationship is a very complex phenomenon. Not al members of a population are vector - somekill the pathogen, others get killed by it and some act as host. It depends upon the genome structure of a particular geographical population.. There are many examples: a species is a vector in a particular geographical environment but not in the other. An interesting example is the behaviour of US malira vector which digest / destroy indian strain of P. falciparum, but Indian malaria vector efficiently transmit US strain of P. falciparum.. Molecular biology may furnish the answer. l

How can one be sure that the pathogens do not affect the vectors. Mosquitoes are not the natural harbors of these organisms. The relative vector density correlate with the transmission intensity of the disease in question [dengue with aedes]. Comparison of the mosquitoes [with the pathogen/without the pathogen] on life span and parity status can be assessed. Still, the answer may not be complete. lalitha kabilan

Experimental infection of various population of Culex pipiens complex with Wuchereria bancrofti, by us, has shown that fecundity and life spans has been affectec negatively

I found this article after my students asked about malaria:

http://www.nytimes.com/2006/04/28/science/28malaria.html?_r=0

Would someone who is more knowledgeable about the disease care to comment on it?

Indeed malaria is the biggest single cause of mortality in human beings – killing men women and children of all ages from new born to senile people. Anopheline mosquitoes are the vectors, which besides transmitting the malarial parasite from person to person provide sexual developmental environment to the parasite. But not all species of anopheline are vector and not all members of a vector species are capable to harbour the parasite. Some kill the parasite, some get killed and some provide developmental environment to the parasite. No system has been found absolutely effective to eliminate malaria. Malaria Eradication Programme, launched worldwide by WHO, failed miserably because of its wrong philosophy. Mosquitoes as well as malarial parasites are living on this planet earth millions of year before Homo sapiens arrived. Mosquitoes found a new and easy source of blood supply to develop eggs. New species of malarial parasites evolved in human species as the primary and secondary host (Plasmodium species of human malaria have not been found in wild or domestic species, as far as I know). Like genetic susceptibility of mosquitoes to malarial parasite, all human beings are not susceptible to malarial parasites infection. Certain population groups and individual harbour the malarial parasite without any ill effect. The trinity of “man–mosquito-malarial parasite” is very complex and has a large number of variables. Man has tried to eliminate malarial parasite and failed but think for a moment if malarial parasite intends to take revenge, what will happen? Please don’t get alarmed; malarial parasite will never do it. It does not want to kill its host. Nevertheless We have to devise ways and means to protect ourselves from mosquito, which are not good carrier host of malarial parasite. God save mosquitoes and us from malarial parasites.

They do get affected! I will not say anything since a lot of fellow researches have already said enough, specially regarding Plasmodium.

I will only contribute with a dengue paper showing that A. aegypti for example, do get affected by the virus.

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0059933

Several have already responded that indeed insect hosts/vectors are generally harmed by the parasite. This harm may seem less important since most insects that carry pathogens infectious to humans are not long-lived and are typicall r-strategists. I will add to this discussion by bringing up a comparable situation with snails that are intermediate hosts for trematode parasites such as schistosomes. Many studies have shown that trematodes are typically very harmful to their snail hosts, with consequences ranging from parasitic castration of the snails to high mortality rates among infected snails. But, like the insects, whether infected or not, these freshwater gastropods tend to be relatively short-lived and r-strategist. In other words, if you were an Anopheles you wouldn't like malaria, and if you were a Biomphalaria you wouldn't like schistosomiasis. You might even dislike those nasty Homo sapiens that carry these diseases to you.

Ha ha, well said David. Every species on earth, including that of Homo, has good and bad points. Mosquitoes and other haematophagus species are forced to take blood meal, not so much for survival but for reproduction. Thus it is an obligatory necessacity. Human beings are omnivotous - for taste and survival, but the quality and quantity is also responsible for reproduction - though it is not important for many. But for Anopheles blood meal is important for the survival of its race..

well .... in case of Plasmodium and female anopheles, it is very well established that, during the sexual stages of plasmodium ( which takes place in the mosquito), in order survive and thrive inside the mosquito midgut, plasmodium has to infect the mosquito ! and in many cases, the mosquito doesn't  survive to transmit malaria, when the parasite load is too much to bear for the mosquito. So, in reality the mosquito is not an accomplice of plamodium against us, rather it is a victim of plasmodium like us ! and it is only those mosquitoes that areable to keep the population of plasmodium in them , in check are able to live long enough to transmit the disease !

In fact in 2011, there was a publication that said that during plasmodium infection in mosquito, the mosquito midgut microbiota plays a very crucial role in inhibiting plasmodium growth.

I have attached that paper for your reference .

Hope it helps !

Regards,

Manish

http://www.sciencemag.org/content/332/6031/855.long

The evidence seem to support a general overall suffering of humans and mosquitos by infections with various virus or parasites but the evidence also shows that the incidence of infection appears to increase over time. Maybe the advantage a infected mosquito has over a non-infected mosquito is too small to measure using current experimental  techniques. Perhaps the larva stage has an advantage? In a r-strategist numbers game, a 0.5% avantage would be enough.

This is a question in meat industry too. The outbreak of HO157 e.coli was due to the partial intestinal bleeding within the cow gut which led to a more favourable environment for the bacteria.