Is Borrelia Transmitted from Mosquitoes?

Mosquito carriers of borrelia bacteria
6 min read

When people typically think about Lyme disease, they associate it with ticks – deer ticks, to be exact. While Lyme has historically been considered a tick-borne disease, more recent scientists and researchers have started to claim that mosquitoes can also infect people with Lyme disease.

Of course, like most ground-breaking science, the claims have been met with controversy in the academic realm of the Lyme disease discussion. Despite many scientific claims showing that mosquitoes can carry Borrelia in their gut and indicating the possibility that mosquitoes are capable of transmitting an infection to humans, many mainstream disease centers still hold otherwise. For instance, even the Centers for Disease Control and Prevention (CDC) website says that “[t]here is no credible evidence that Lyme disease can be transmitted through air, food, water, or from the bites of mosquitoes, flies, fleas, or lice.”

Understanding the controversy over whether mosquitoes can infect people with Lyme disease can be very confusing, especially since scientists have already determined that mosquitoes can carry the Borrelia bacteria. The issue, however, isn’t quite whether mosquitoes have been found to carry Borrelia. Instead, the question is whether Borrelia and mosquitoes can interact with one another in a way that enables the Borrelia to be transmitted from mosquito to human.

Transmitting the Lyme infection from a tick to a person is not necessarily a matter of the tick sucking Borrelia from one person and injecting it into another. Rather, there are certain relations, processes, and systems inside the tick and Borrelia that enables it to persist for a long enough time to become strong enough to be transmitted to a person. Understanding how the Lyme disease organism, Borrelia, works in a tick is crucial when it comes to understanding the controversy over mosquitoes and Lyme disease.

Lyme disease exposure from tick bite

Lyme Disease in Ticks:

As we mentioned above, when it comes to the transmission of Lyme disease, ticks are not necessarily flying bug syringes that suck Borrelia from one organism and then simply inject it into another. The process, of course, is a little more complicated as it is the interactions between two living things, the tick, and Borrelia, that play a crucial role in the transmission of the infection.

While Borrelia resides in the tick’s gut, it produces a protein that enables the Borrelia to persist in the tick for long periods. The protein aids its survival until the tick feeds again. Then, when the tick begins to feed again, the spirochete decreases its production of that protein and focuses on producing a new protein, which allows the spirochete to move to the tick’s salivary gland where it can then be transmitted to the new host by way of the tick’s saliva.

The production and function of the two proteins that the Borrelia spirochete produces in a tick are integral to the Borrelia’s survival. Still, it also can enhance and utilize a protein already in the tick that protects not only the tick but the spirochete as well from any attacks by the host’s immune system. Therefore, Borrelia is dependent on the tick’s protein, Salp15, to infect the host as a Lyme disease agent. In addition to the Salp15 protein, the Borrelia also needs the extended time that a tick spends feeding, as it often feeds for multiple days at a time. The spirochetes often require such an extended amount of time for those interactions to occur.


Mosquitoes Carry Lyme Disease

Contrarily, Borrelia is much less equipped for survival in mosquitoes. So, despite being found to exist in mosquito guts, and even saliva, people question whether it can survive long enough in the mosquito without the support from the proteins found in ticks. Additionally, mosquitoes take only a few minutes, sometimes even seconds, to feed, whereas ticks take days. Such a short amount of time reduces the spirochetes’ ability to produce whatever equipment they might need to be viable as infectors of Lyme disease in the same way as they are with ticks.

Such concerns have made mainstream disease centers deny that mosquitoes have the capacity to be significant vectors of Lyme disease infections. However, recent studies have provided evidence to combat any such concerns. Specifically, one study performed by individuals from Goethe-University, Senckenberg Museum of Natural History Gorlitz, and the University of Frankfurt have found that mosquitoes might have the equipment, after all, to enable Borrelia spirochetes the ability to survive for the duration necessary to be viable vectors of Lyme disease.


Mosquito Study from German Universities

The researchers in this study aimed to check two things. First, whether Borreliae can be found in different species, or even different genera, of mosquitoes despite their different feeding habits, and secondly, whether Borreliae can be detected in mosquitoes right after their metamorphosis just as the transstadial transmission (the passage of a microbial parasite from one developmental stage of the host to the next) in ticks.

In regards to the first goal of the study, the researchers found that Borreliae could be detected in 10 species of mosquitoes across four different genera. This was out of the 52 species of mosquitoes found in the tested areas of Germany. The frequency of the bacteria found in mosquitoes was consistent with previous studies, and the number of species it was found it was due to collection methods and not differences between the species. In line with previous studies, a notable amount of Borriliae was detected in the mosquitoes’ salivary glands, indicating the possibility that mosquitoes can transmit an infection. Regarding the first goal, the study did not find evidence to show anything conclusively. Still, the findings do suggest that mosquitoes might play the role of being an occasional mechanical vector of Lyme disease.

On the other hand, this study found ground-breaking data in relation to the second goal, which was to find out whether Borreliae can be detected in mosquitoes directly following their metamorphoses. Such findings would be significant because being able to survive and continue from one developmental stage of the host to the next is a crucial step for any vector-borne pathogen to be transmitted later on.

This study, for the first time, found that Borreliae endure the metamorphosis from larvae to pupae, and again from pupae to a mosquito. The study confirmed this by capturing larvae, which were tested to have Borreliae. Then, while monitoring the laboratory-hatched specimens at each stage of their metamorphosis, the researchers were able to confirm that the mosquitoes maintained the Borrelia in their organism through the changes despite never having a blood meal. These findings were the first of their kind, and indicate that the Borriliae in mosquitoes have developed some form of survival methods in mosquitoes, which quiets the concerns concerns of those who might be skeptical of mosquitoes having the capacity to transmit infectious Borrelia to people.

8 thoughts on “Is Borrelia Transmitted from Mosquitoes?”

  1. Avatar of robert

    Interesting and more than a little thought provoking. We should check out some of the biting flies too!

    1. Avatar of t. Sali

      If, as reported, Borrela survives metamorphosis from the larval stage in mosquitos, how do the larvae acquire it in the first place?!!?

  2. Avatar of michelle thomas
    Michelle Thomas

    Thank you for posting this was very informative. I have been trying to learn more about Lyme and there is so much information out there and not a lot of actual research backing up claims so it is hard to know what is truth. Do you have a link to this study? Thank you.

  3. Avatar of m martin

    My husband tested positive for Lyme disease last week. We know without a shadow of doubt he contracted it through mosquitos in Tianjin, China in June of 2016. After being bitten by several outside our apartment one evening, the next morning his eye was swollen shut. His bite wounds swelled between golf ball and softball size. I’ve never seen anything like it. We knew there was something seriously wrong with those mosquitos. The past year and a half my husband has battled joint pain that leaves him in tears, heart palpitations, chronic fatigue, brain fog, etc. We thought it was all due to stress from his job or some sort of arthritis. He tested positive for Lyme last week. So now we are learning all we can. I know it was through those mosquitos.

  4. Avatar of heidi

    I too know without shadow of a doubt that I contracted Lyme from a mosquito bite.

    There I was in a swarm of mosquitoes, a few of them bit me, and one bite immediately itched so terribly that I ‘tended’ to it as best I could at that time. The rash started developing soon into a clear bulls eye rash. Checking all relevant sources (esp. the site) we were convinced that this couldn’t be Lyme as the CDC stated then (2013) and still does now (2018) that only ticks can transmit this disease.

    So I kept on rubbing anti itch stuff on my rash. Months later, my husband brought me to the ER when, on a weekend, my body was close to a final breaking point. The nice doc diagnosed me with Lyme just by looking at my by-then HUGE rash; he said a blood test wouldn’t be necessary to diagnose this disease in my case but he did it anyway (I guess, they have to do it). The test came back positive.

    I contacted the CDC and requested they change the information on their site to let people know that Lyme can be transmitted by animals other than ticks, so that other people can avoid delaying proper treatment as I did. Waiting too long to intervene can cause chronic disease and the CDC, I thought, should be interested in avoiding this by putting more accurate information on their site, at least they shouldn’t exclude any vectors as explicitly as they did then (and still do). They apparently don’t care about people’s suffering.

    I am grateful for places like this which helps alert people to the possibility of non-tick transmitted Lyme disease. Thank you!!

  5. Avatar of sibylle salinger
    Sibylle Salinger

    Thank you for explaining this subject so it can be easily 6nderstood. In 2015, I contracted Lyme disease from a mosquitoe in Denmark. I have no doubt that it was a mosquitoe, because I got aware of it while it was sucking blood from my thigh. 5 days later, there came a rash around the mosquitoe bite which developed into a bull’s eyes rush, with the mosquitoe bite in the center. There was no tick involved at all. I went to the doctor and he prescribed antibiotics, I didn’t mention the mosquitoe as a vector though, because the doctor would have dismissed the possibility.

  6. Avatar of teresa lee-hockett
    Teresa Lee-Hockett

    Absolutely true. I probably had Lymes Disease for years since I was 15 and infected by a tick but it didn’t give me any real problems besides mitral valve prolapse, left kidney problems and thyroid issues. Then one day whilst living in Cyprus 2011 at the time of the Libyan war the black helicopters that kept going over us every week dropped a mass of GM mosquitoes on us. My husband got cancer and I got this awful biofilm borrellia. Luckily I learnt to give up going to the Hospital as they thought I was nuts and worked with Caroline Carter who told me all about how we really contact this weaponised disease. Only natural products and homeopathy is the answer.

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