Can mosquitoes spread coronavirus?


Cameron Webb, University of Sydney

The pathogens mosquitoes spread by sucking our blood cause over half a million deaths each year and hundreds of millions of cases of severe illness.

But there is no scientific evidence to suggest mosquitoes are transmitting SARS-CoV-2, the virus that causes COVID-19.

There is much more to learn about the coronavirus but based on current understandings, it’s highly unlikely a mosquito will pick up the virus by biting an infected person, let alone be able to pass it on.




Read more:
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Yes, mosquitoes can transmit other viruses

Female mosquitoes need the nutrition contained in blood to help develop their eggs. Viruses take advantage of this biological requirement of mosquitoes to move from host to host.

But for a mosquito to become infected, it first needs to bite an infected animal, such as a bird or kangaroo, or a person.

Mosquitoes can transmit a number of viruses, including dengue, yellow fever, chikungunya, Zika and Ross River virus. They can also transmit malaria, which is caused by a parasite.

But they can’t transmit many other viruses, including HIV and Ebola.

You can’t catch the coronavirus, HIV or Ebola from mosquitoes, but they can transmit a number of other viruses.
Holly Mandarich/Unsplash

For HIV, mosquitoes themselves don’t become infected. It’s actually unlikely a mosquito will pick up the virus when it bites an infected person due to the low concentrations of the HIV circulating in their blood.

For Ebola, even when scientists inject the virus into mosquitoes, they don’t become infected. One study collected tens of thousands of insects during an Ebola outbreak but found no virus.

No, not coronavirus

The new coronavirus is mostly spread via droplets produced when we sneeze or cough, and by touching contaminated surfaces.

Although coronavirus has been found in blood samples from infected people, there’s no evidence it can spread via mosquitoes.




Read more:
Feel like you’re a mozzie magnet? It’s true – mosquitoes prefer to bite some people over others


Even if a mosquito did pick up a high enough dose of the virus in a blood meal, there is no evidence the virus would be able to infect the mosquito itself.

And if the mosquito isn’t infected, it won’t be able to transmit it to the next person she bites.

Why some viruses and not others?

It’s easy to think of mosquitoes as tiny flying dirty syringes transferring droplets of infected blood from person to person. The reality is far more complex.

When a mosquito bites and sucks up some blood that contains a virus, the virus quickly ends up in the gut of the insect.

From there, the virus needs to infect the cells lining the gut and “escape” to infect the rest of the body of the mosquito, spreading to the legs, wings, and head.

The virus then has to infect the salivary glands before being passed on by the mosquito when it next bites.

This process can take a few days to over a week.

But time isn’t the only barrier. The virus also has to negotiate getting out of the gut, getting through the body, and then into the saliva. Each step in the process can be an impenetrable barrier for the virus.

This may be straightforward for viruses that have adapted to this process but for others, the virus will perish in the gut or be excreted.




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The Conversation


Cameron Webb, Clinical Associate Professor and Principal Hospital Scientist, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Feel like you’re a mozzie magnet? It’s true – mosquitoes prefer to bite some people over others



Photo by Eric Nopanen on Unsplash, CC BY

Cameron Webb, University of Sydney

It’s always you, isn’t it? The person busy swatting away buzzing backyard mosquitoes or nursing an arm full of itchy red lumps after a weekend camping trip.

You’re not imagining it – mosquitoes really are attracted to some people more than others.

Why do mosquitoes need blood?

Only female mosquitoes bite. They do it for the nutrition contained in blood, which helps develop their eggs.

Mosquitoes don’t just get blood from people. They’re actually far more likely to get it from biting animals, birds, frogs and reptiles. They even bite earthworms.

But some mosquitoes specifically target people. One of the worst culprits is the Aedes aegypti species, which spreads dengue and yellow fever viruses.

Another that prefers humans are the Anopheles mosquitoes, responsible for spreading the parasites that cause malaria.




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How do mosquitoes find us?

Most mosquitoes will get their blood from whatever is around and don’t necessarily care if they’re biting one person or another.

Although it’s our blood they’re after, there is no strong indicator they prefer a particular blood type over another. Some studies have suggested they prefer people with type O blood but that’s unlikely to be the case for all types of mosquitoes.

Whether we’re picked out of a crowd may come down to heavy breathing and skin smell.

When they need blood, mosquitoes can pick up on the carbon dioxide we exhale. Around the world, carbon dioxide is one of the most common “baits” used to attract and collect mosquitoes. If you’re exhaling greater volumes of carbon dioxide, you’re probably an easier target for mosquitoes.




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When the mosquito gets closer, she is responding to a range of stimuli.

Perhaps it’s body heat and sweat: exercise that increases body temperature and perspiration can attract mosquitoes.

Perhaps it’s body size: studies indicate pregnant women are more likely to be bitten by mosquitoes.

How hairy are you? Mosquitoes may have a tough job finding a path through to your skin if there is an abundance of body hair.




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More than anything else, though, it’s about the smell of your skin. Hundreds of chemicals are sweated out or emitted by our body’s bacteria. The cocktail of smells they create will either attract or deter mosquitoes.

The saltmarsh mosquito is one of the biggest nuisance-biting pests in Australia.
Dr Cameron Webb

It’s not just who they bite but where

Mosquitoes could also have a preference for different parts of the body.

One study showed mosquitoes are more attracted to hands and feet than armpits, but that just turned out to be because of deodorant residues.

Mosquitoes may also be more attracted to our feet: studies have shown cheese sharing similar bacteria to that found between our toes attracts mosquitoes!

Who is to blame for this misery?

It’s not your diet. There is no evidence that what you eat or drink will prevent mosquito bites. Some food or drink may subtly change how many mosquitoes are likely to bite you but it won’t make that much difference.

Eating bananas or drinking beer has been shown to marginally increase the attraction of mosquitoes but the results aren’t enough to suggest any dietary change will reduce your mosquito bites. That’s why our supermarket shelves aren’t full of “mozzie repellent” pills.




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Your irresistibility to mosquitoes may not be your fault. Blame your parents. Studies have shown the chemicals responsible for the “skin smell” that attracts mosquitoes has a high level of heritability when twins are exposed to biting mosquitoes.

Whether you’re a mosquito magnet or not, topical insect repellents are the best way to stop mozzie bites.
Dr Cameron Webb

What can you do about it?

We have to be careful about generalisations. There are thousands of types of mosquitoes around the world and all will have a different preference for what or who to bite. And the attraction of individuals and the scenario that plays out in one part of the world may be much different in another.

Remember, it only takes one mosquito bite to transmit a pathogen that could make you sick. So whether you’re a mosquito magnet or feeling a little invisible because you’re not bitten so often, don’t be complacent and use insect repellents.The Conversation

Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

As heat strikes, here’s one way to help fight disease-carrying and nuisance mosquitoes



Although yellow fever does not currently exist in Australia, the species Aedes aegypti – which can transmit the disease – is found widely across northern Queensland. The virus remains a global health concern, but citizen scientists could help prevent its spread.
Simon Kutcher/flickr, CC BY

Cameron Webb, University of Sydney; Craig Williams, University of South Australia; Larissa Braz Sousa, University of South Australia; Seamus Doherty, University of South Australia, and Stephen Robert Fricker, University of South Australia

Mosquito-borne disease is a concern for health authorities around Australia. Each year, thousands fall ill to Ross River virus disease caused by mosquito bites.

Tracking mosquito populations can help us respond to these threats, and new research suggests citizen scientists may be the key to doing this more effectively.

Health authorities coordinate the surveillance of mosquitoes and their pathogens. These surveillance data help improve the understanding of mosquito-borne disease outbreaks.

They also help guide public education campaigns, and assist in mosquito control efforts, often through the application of insecticides.




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However, there aren’t enough resources to set mosquito traps everywhere. It can also be tricky getting specimens from the field to the lab for testing. This is where citizen science is important.

This public-led movement involves volunteers gathering scientific data for programs coordinated by professional scientists, simply through taking photos or recording sounds on their smartphones.

In this way, sightings of animals and plants can be reported. Citizen scientists can even help in experimental design, data analysis and distribution of research results.

Getting bu-zzzz-y tracking mosquitoes

One program called Mozzie Monitors, launched in June last year, is shedding light on how citizen science can address critical resource shortages in mosquito surveillance efforts.

Our research published last week in Science and the Total Environment reveals how the program’s use of smartphone e-entomology (“e” stands for electronic) is enabling the low-cost upscaling of mosquito surveillance.

The program involves recruiting volunteers to set up cheap and simple mosquito traps in their backyards, and use their smartphones to send back data on the caught mosquitoes.

Mozzie Monitors volunteers used a simple BG-GAT trap to catch mosquitoes.
Cameron Webb/NSW Health Pathology, Author provided

A crowd-funding campaign attracted donations from over 150 people to help launch the program, from which 126 people became actively involved in data collection.

Each participant was provided with an easy-to-use Biogents BG-GAT (Gravid Aedes Trap) and asked to email the research group with photos of collected mosquitoes. Scientists were then able to use these photos to identify and count the different species collected. This approach is called e-entomology.

The volunteers sent more than 10,000 photos of mosquitoes to scientists. From these, 15 different species were identified, ranging from Aedes notoscriptus (the common Australian backyard mosquito) to Aedes camptorhynchus, a mosquito flying into suburbs from nearby coastal wetlands.

The number of mosquitoes changed throughout the year in response to changing temperatures. Unsurprisingly, they hit their peak during summer.




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The value of citizen science data

The Mozzie Monitors program marks the first time formal mosquito trapping has been combined with citizen science.

A key research question for us was: do the data collected by citizen scientists align with data collected in formal mosquito surveillance programs?

To test this, the data collected by Mozzie Monitors volunteers were compared to data collected from a professional program monitoring mosquitoes around urban wetlands. Mosquitoes associated with these wetlands can pose pest and public health risks.

The citizen scientists contributed more than four times the amount of data than professional monitoring efforts. This included locally important species known to spread Ross River virus.

In terms of the number and diversity of mosquitoes collected, citizen science proved just as reliable as a professional program.

Other victories

There has been growing interest in the potential of citizen science to assist the surveillance of mosquitoes associated with nuisance-biting and disease risks.

In Brisbane, the Metro South Public Health Unit’s Zika Mozzie Seeker program has sought to detect the arrival of exotic mosquitoes that may increase the risk of potentially serious diseases caused by the dengue, chikungunya, or Zika viruses.




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In Spain last year, citizen scientists using the Mosquito Alert app for smartphones detected the arrival of an invasive mosquito, Aedes japonicus, before local authorities could.

Where to now?

The citizen science movement is growing across the world, promoting life-long learning among citizens.

It’s important communities continue to be made aware of their potential role in wildlife surveillance efforts.

By engaging the public in Mozzie Monitors, we’ve been able to integrate citizen science with a professional programs to boost mosquito surveillance.

Now, more mosquitoes can be trapped in more locations, giving health authorities a clearer picture of potential health risks. This also increases our chances of detecting invasive species that are a biosecurity threat.

Apart from monitoring mosquitoes, the Mozzie Monitors program is educating communities about mosquito diversity in their own backyards, and helping raise awareness of local disease risk.

As mosquitoes were identified during the trial, results were made available on the research group website. Citizen scientists were updated monthly on the distribution and frequency of mosquitoes in and around their suburbs. This encouraged many participants to identify mosquitoes they collected themselves.

The program’s next trial has already started in South Australia, and everyone is welcome to get involved.The Conversation

Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of Sydney; Craig Williams, Associate Professor in Biology, University of South Australia; Larissa Braz Sousa, PhD candidate on citizen science and public health, University of South Australia; Seamus Doherty, Biologist, University of South Australia, and Stephen Robert Fricker, Manager of Vector Surveillance, University of South Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

After the floods come the mosquitoes – but the disease risk is more difficult to predict


Cameron Webb, University of Sydney

We’re often warned to avoid mosquito bites after major flooding events. With more water around, there are likely to be more mosquitoes.

As flood waters recede around Townsville and clean-up efforts continue, the local population will be faced with this prospect over the coming weeks.

But whether a greater number of mosquitoes is likely to lead to an outbreak of mosquito-borne disease is tricky to predict. It depends on a number of factors, including the fate of other wildlife following a disaster of this kind.

Mozzies need water

Mosquitoes lay their eggs in and around water bodies. In the initial stages, baby mosquitoes (or “wrigglers”) need the water to complete their development. During the warmer months, it doesn’t take much longer than a week before they are grown and fly off looking for blood.

So the more water, the more mosquito eggs are laid, and the more mosquitoes end up buzzing about.

But outbreaks of disease carried by mosquitoes are dependent on more than just their presence. Mosquitoes rarely emerge from wetlands infected with pathogens. They typically need to pick them up from biting local wildlife, such as birds or mammals, before they can spread disease to people.




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Mosquitoes and extreme weather events

Historically, major inland flooding events have triggered significant outbreaks of mosquito-borne disease in Australia. These outbreaks have included epidemics of the potentially fatal Murray Valley encephalitis virus. In recent decades, Ross River virus has more commonly been the culprit.

A focal point of the current floods is the Ross River, which runs through Townsville. The Ross River virus was first identified from mosquitoes collected along this waterway. The disease it causes, known as Ross River fever, is diagnosed in around 5,000 Australians every year. The disease isn’t fatal but it can be seriously debilitating.

Following substantial rainfall, mosquito populations can dramatically increase. Carbon dioxide baited light traps are used by local authorities to monitor changes in mosquito populations.
Cameron Webb (NSW Health Pathology)

In recent years, major outbreaks of Ross River virus have occurred throughout the country. Above average rainfall is likely a driving factor as it boosts both the abundance and diversity of local mosquitoes.

Flooding across Victoria over the 2016-2017 summer produced exceptional increases in mosquitoes and resulted in the state’s largest outbreak of Ross River virus. There were almost 1,700 cases of Ross River virus disease reported there in 2017 compared to an average of around 300 cases annually over the previous 20 years.




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Explainer: what is Ross River virus?


Despite plagues of mosquitoes taking advantage of flood waters, outbreaks of disease don’t always follow.

Flooding resulting from hurricanes in North America has been associated with increased mosquito populations. After Hurricane Katrina hit Louisiana and Mississippi in 2005, there was no evidence of increased mosquito-borne disease. The impact of wind and rain is likely to have adversely impacted local mosquitoes and wildlife, subsequently reducing disease outbreak risk.

Applying insect repellent is worthwhile even if the risk of mosquito-borne disease isn’t known.
From shutterstock.com

Australian studies suggest there’s not always an association between flooding and Ross River virus outbreaks. Outbreaks can be triggered by flooding, but this is not always the case. Where and when the flooding occurs probably plays a major role in determining the likelihood of an outbreak.

The difficulty in predicting outbreaks of Ross River virus disease is that there can be complex biological, environmental and climatic drivers at work. Conditions may be conducive for large mosquito populations, but if the extreme weather events have displaced (or decimated) local wildlife populations, there may be a decreased chance of outbreak.

This may be why historically significant outbreaks of mosquito-borne disease have occurred in inland regions. Water can persist in these regions for longer than coastal areas. This provides opportunities not only for multiple mosquito generations, but also for increasing populations of water birds. These birds can be important carriers of pathogens such as the Murray Valley encephalitis virus.




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In coastal regions like Townsville, where the main concern would be Ross River virus, flood waters may displace the wildlife that carry the virus, such as kangaroos and wallabies. For that reason, the flood waters may actually reduce the initial risk of outbreak.

Protect yourself

There is still much to learn about the ecology of wildlife and their role in driving outbreaks of disease. And with a fear of more frequent and severe extreme weather events in the future, it’s an important area of research.

Although it remains difficult to predict the likelihood of a disease outbreak, there are steps that can be taken to avoid mosquito bites. This will be useful even if just to reduce the nuisance of sustaining bites.

Cover up with long-sleeved shirts and long pants for a physical barrier against mosquito bites and use topical insect repellents containing DEET, picaridin, or oil of lemon eucalyptus. Be sure to apply an even coat on all exposed areas of skin for the longest lasting protection.The Conversation

Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Muslim Groups Demand Closure of Large, Legal Church in Indonesia


Hundreds of demonstrators from outside area try to create image of local opposition.

JAKARTA, Indonesia, February 25 (CDN) — Hundreds of Muslims from outside the area where a 600-member church meets in West Java staged a protest there to call for its closure this month in an attempt to portray local opposition.

Demonstrators from 16 Islamic organizations, including the hard-line Islamic Defenders Front (FPI), gathered on Feb. 15 to demand a stop to all activities by the Galilea Protestant Church (GPIB) in the Galaxy area of Bekasi City.

The Rev. M. Tetelepta, pastor of the church, told Compass that the church has had the required consent of local residents and official permission to worship since its inception in 1992.

“From the beginning we had permission to worship from both the government and the nearby residents,” Tetelepta said. “We worked on the building permit and had received principle clearance from the mayor of Bekasi. We had also received permission from the Bekasi Interfaith Harmony Forum.”

At the Galaxy area demonstration, FPI Bekasi branch head Murhali Baeda tried to impugn the legal status of the Galilea church by telling ANTARA, the official news agency of the Indonesian government, that he was “certain” that “a number of the church buildings” in the area “do not have complete permission.”

“This is proved by the large number of posters and banners that are displayed in the alleys and public gathering places rejecting the presence of these [church] buildings,” Murhali told ANTARA.

A Joint Ministerial Decree promulgated in 1969 and revised in 2006 requires the permission of more than 60 neighbors and a permit from local authorities to establish a place of worship in Indonesia.

Representatives of Islamic organizations at the demonstration shouted, “Churches are not allowed in Galaxy” and carried posters and banners declaring, “We Faithful Muslims Reject the Presence of Churches,” as well as “Beware of Christianization of Galaxy.”

Local organizations represented at the demonstration included the Bekasi Dakwah Council, the Bina An Nisa Dakwah Council of Bekasi and the Galaxy Mosque and Mushola Forum, but Tetelepta said he was sure that 95 percent of the protestors were not local people.

Also present at the demonstration were representatives of the Islamic Youth and Student Forum, Islamic Unity, the Committee to Enact Syariah (Law), Muhammadiyah, the Islamic Youth Movement, the Syariah Concern Society, the Islamic Youth Federation, the Bungin Dakwah Council, the Gembong River Society, Irene Centre and the Indonesian Mujahadin Council.

Baeda of the FPI accused the church of “Christianizing” local residents by distributing food “and the nine essentials at a reduced price.”

“The church is distributing these things as incentive to confess Jesus as their Lord,” Baeda told Compass. “We have received several reports of this from people who have accepted these distributions.”

This type of activity disturbs society, he added. “I consider this wrong-doing.”

The local FPI leader told ANTARA that there are at least six churches and a number of homes that function as churches.

“At night praises to their God in the form of songs disturbs the people’s sleep,” he reportedly said.

Tetelepta denied that the church had tried to “Christianize” people.

“We have never distributed food or the nine essentials,” he said. “The only thing we have done is to spray for mosquitoes near the church.”

Before coming to Galaxy the congregation had worshipped in various places in Bekasi. At the suggestion of the government, Tetelepta said, the church purchased the property in Galaxy in 2006 in order to construct a worship place.

He added that there has been an effort to discredit the church in the Bekasi area.

“Our worship services will continue as usual in spite of the demonstrations,” he said. “We are coordinating things with the police.”

Report from Compass Direct News