Remains a theoretical risk but there are no documented transmissions. Hep viruses are destroyed in the mosquito gut.

The female Anopheles mosquito injects saliva into its bite. Blood is not injected so the risk is very negligible.

We research about this theoritical risk and what we found was the prevalence of HBV in malaria patients was higher than non-malaria patients(P

That is really interesting, Prof Sharifi-Mood! Is this published? What is the OR of malaria patients having HBV and is this HB surface antigen positivity or core antibody positivity?

As far as I know it can't be transmited

Dear Achyuta, I am teaching at Zahedan University of medical sciences in Southeastern Iran, where the prevalence of HBV and Malaria are higher than other region of Iran .We searched it about 8 years ago .it was a project that I was superviser. Paper has published in a local journal(Journal of research in health sciences,Hamadan Iran).

There is no evidence for this possibility, although theoretically it might be possible. Mosquito can bite infected person then non infected person without sterilization of its needle.

Hepatitis B yes theoretically possible because the blood necessary for transmission is very less(o.o3ml). and when a mosquito bites there is a chance of regugutation og blood from mosquito .HCV may not be transmitted

Why we rule out transmission as yet is that the viruses do not survive mosquito and that the amount of blood required for transmission is quite less

Prof. Sharifi-Mood, your publication appears as very interesting: it is possible to get a PDF copy of it? Also in farsi (I understand a little bit of it).

Dear Ramana, a little big question still remains: HCV is a Flaviviridae like Dengue, like Yellow Fever virus ans so on. We may guess that a common ancestor was actually transmitted by mosquitos or haematophagus arthropods: it is possible that in some particular conditions HCV may revert to this very ancient habit? And also: how HCV did spread globally in a world without e.g. blood transfusions, medical devices, surgical procedures...

Hi Ramana,

That is consistent with my reading of the medical and research literature.

There is a popular science magazine article here discussing Matteo's points re flaviviruses;

>>

http://news.sciencemag.org/sciencenow/2001/06/04-04.html

The reason I don't believe mosquitos can transmit HCV, is because a mosquito's "needle", (the proboscis), is actually a complex structure that has separate channels. When a mosquito bites, it injects saliva through one channel. The saliva functions as a lubricant to help the mosquito feed easier. The blood it sucks as a meal flows in a completely separate channel and only in one direction: toward the mosquito.

So, it's biologically very unlikely that infected blood could be spread to another person, and there is no evidence that mosquitos can transmit HCV or HIV.

Mosquitos can spread diseases that can be transmitted by injected saliva, and might also regurgitate a small amount of ingested blood, so they could theoretically transmit HBV;

http://www.ncbi.nlm.nih.gov/pubmed/7400629

.

Article An animal study on transmission of hepatitis B virus through...

However in real world settings this doesn't seem to occur. As mosquitoes don't have a liver, it's unlikely any HBV that survived ingestion and digestion would be able to replicate or spread to a new host.

Paul.

Dear Matteo,

You ask;

>

Hepatitis C can be transmitted vertically (mother to child). There is a slightly less than 10% chance of this, (unless there is HIV co-infection, when the risk ranges between 10 and 50%).

http://www.ncbi.nlm.nih.gov/pubmed/9563703

Int J Epidemiol. 1998 Feb;27(1):108-17.

HCV can also be transmitted through routes such as very rough unprotected penetrative sex, (especially when there are lesions- eg: co-infection with an STI), via injuries sustained in fist-fighting, and any other opportunities for blood-to-blood contact. These are extremely low-risk routes, compared to injecting drug use or blood transfusion with unscreened blood, but there are documented cases in the literature.

HCV probably only began spreading very widely during the 19th and early 20th C. First the invention of the hypodermic syringe, then the advent of anaesthetics (allowing serious invasive surgery) and of blood transfusions would have spread it very quickly. Although doctors like Semmelweiss, Lister and Pasteur had conclusively proved the "germ theory" of infection much earlier, the majority of Doctors did not begin sterilising instruments until the early 20thC.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1692621/pdf/medlibhistj00003-0001.pdf

.

Most Doctors until the very late 19thC still attributed infectious diseases to the "miasma" theory. This stated that infectious diseases were transmitted by exposure to noxious air. Interestingly, that is why malaria is called malaria- it is Medieval Italian; "Mal Aria" = "Bad Air".

Blood products were not screened for HCV until 1990, because we had no idea that the virus even existed before the late 1980s, and then had to develop an antibody test to detect it.

>

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1472033/

.

J Virol. 2006 May; 80(9): 4220–4226.

doi: 10.1128/JVI.80.9.4220-4226.2006

Regards,

Paul.

There are a few other examples of means of BBV transmission that might predate blood transfusions and injection technology;

For example blood rituals, ritual circumcision or ritual scarring in tribal initiations, and medical blood letting, barbers using the same razor on all customers, etc. These are all very low risk.

The fact that the most dominant strains of HCV (1a, 1b, and 3a) show very little genetic variation indicates that they either crossed into the human population or emerged from a small subset of the human population very recently, probably in the late 19th and early 20thC, as I mentioned above.

Ramana pointed the extremely small amount of blood needed to transmit HBV.

When injecting equipment is shared, any viral material in the infectious blood is being introduced directly into the second person's bloodstream. The chances of transmission are fairly high.

By contrast, when a mosquito bites you it isn't tapping a major blood vessel. It is more analogous to a needle-stick-injury (NSI) than to people sharing a syringe.

In an NSI, whatever infectious blood is left on the needle is being pushed into the skin. However wounds bleed with outward force before clotting, so that fungi, bacteria or viruses have less chance of entering the body.

In contrast to a non-sterile intravenous injection, if such infectious material does enter the body via a NSI, it is in a much, much smaller quantity and also is not entering the bloodstream directly.

When a phlebotomist or other medical professional suffers a NSI, we often already know (or can quickly test and find out) the sero-status of the patient the blood came from. As a result of studies on occupational NSI, we know that if the patient is HIV+ there is only a 0.4% chance the medico will become infected. If the patient is HCV+ there is less than a 4% chance of transmission, But if the patient is HBV+ there is an almost 25% chance of transmission.

These transmission rates are for occupational exposures. In these cases the blood is very fresh, and the virus(es) it carries are likely to still be viable.

In accidental needle-stick-injuries in community settings, the needle has typically been lying around for hours, days or longer. It has usually been exposed to sunlight. It is very unlikely that HCV or HIV will still be viable in a large enough quantity to transmit infection, if any of it is viable at all.

In fact, in all of the international literature, there are only 3 recorded cases of HIV or HCV being transmitted by an accidental NSI in the community. (There may well be other instances, but there are only three confirmed cases in the world. To put this risk into perspective, in the last hundred years there are two confirmed cases of humans being struck by meteorites). If you suffer a NSI you should be MUCH more concerned about whether you have been immunised against HBV and tetanus.

I would suggest that in terms of passing on HCV or HIV, a mosquito bite is analogous to an accidental NSI in a community setting. If any blood is passed on, it will be in even smaller quantities than in an NSI. It will also have been broken down by the mosquito's digestive enzymes. Accordingly, I would expect that the risk would be astronomically small.

Hope this is helpful,

Regards,

Paul.

Some relevant papers;

http://www.ncbi.nlm.nih.gov/pubmed/15974234

Trop Gastroenterol. 2005 Jan-Mar;26(1):29-30

http://www.ncbi.nlm.nih.gov/pubmed/8728939

Chin Med J (Engl). 1995 Dec;108(12):895-7

I suspect mosquito could transmit B and C,but I read no evidence so far. Therefore, it is better to conduct a deep case study where Hepatitis and/or C is/are prevalent.

The answer is in the saliva. When mosquito bites, it injects its own saliva into whatever it is biting. The diseases spread by mosquitoes are actually spread through the mosquito's saliva. Hepatitis, however, is spread through infected blood.

Asrat Chernet Adeko if you follow some of the links in the replies above, you will find some evidence.

As mentioned above, laboratory animal studies show that HBV and HCV can survive in mosquito tissue for some time. See for example;

http://www.usa-journals.com/wp-content/uploads/2014/09/Tarish_Vol210.pdf

While this study showed persistence of the hepatitis C virus in the tissue of mosquitoes fed on HCV+ blood, the researchers found no evidence of HCV transmissible via the proboscis and feeding parts.

Epidemiological studies show no evidence to support the idea that HBV or HCV can be transmitted by mosquito bites. There are no confirmed cases anywhere in the world of HBV or HCV transmission via mosquito bite. The World Health organization states there is no evidence of any insect vector or animal reservoir for HCV.

There is a good discussion here;

https://www.sciencemag.org/news/2001/06/hepatitis-c-mosquito-bite

and another here;

https://www.verywellhealth.com/spreading-hepatitis-by-mosquitoes-1760047

If mosquitoes were a significant vector for HCV or HBV in humans, we would expect to see high rates of these viruses in areas with high rates of malaria, and there are no such associations between HCV infection and malaria. While HBV and malaria co-infection are very common in Amazonia, both infections are endemic in the region and there is no evidence of transmission of HBV by mosquito bite. While incidence of malaria shows strong seasonal variation, there is no such variation evident in HBV or HCV infection.

Article A prospective epidemiological study to see if mosquito bite ...

Thanks for all the tips! This was extremely helpful