A flesh-eating fly is spreading. It can infest humans and their pets
A flesh-eating parasitic fly is invading North and Central America. The consequences could be severe for the cattle industry, but this parasite is not picky – it will infest a wide range of hosts, including humans and their pets.
The 'New World screwworm' (Cochliomyia hominivorax) was previously eradicated from these regions. Why is it returning and what can be done about it?
Flies fulfil important ecological functions, like pollination and the decomposition of non-living organic matter. Some, however, have evolved to feed on the living.
The female New World screwworm fly is attracted to the odour of any wound to lay her eggs. The larvae (maggots) then feed aggressively on living tissue causing immeasurable suffering to their unlucky host, including death if left untreated.
Cattle farmers in Texas estimated in the 1960s that they were treating around 1 million cases per year.
Between the 1960s and 1990s, scientists and governments worked together to use the fly's biology against it, eradicating the New World screwworm from the US and Mexico using the sterile insect technique (SIT).
A female screwworm mates only once before laying her eggs, whereas the males are promiscuous. During the eradication process, billions of sterile males were released from planes, preventing any female that mated with them from producing viable eggs.
In combination with chemical treatment of cattle and cool weather, populations of the screwworm were extinct in the US by 1982. The eradication campaign reportedly came at cost of US$750 million (£555 million), allowing cattle production to increase significantly.
For decades, a facility in Panama has regularly released millions of sterile flies to act as a barrier to the New World screwworm spreading north from further south.
However, since 2022 – and after decades of eradication – the New World screwworm has once again spread northwards through several countries in Central America. Cases exploded in Panama in 2023 and the fly had reached Mexico by November 2024.
Scientists have suggested several hypotheses for this spread, including flies hitchhiking with cattle movements, higher temperatures enhancing fly development and survival, and the possibility that females are adapting their sexual behaviour to avoid sterile males.
Around 17 million cattle are now at risk in Central America, but worse may be to come. Mexico has twice as many cattle, and the spread towards the US continues, where around 14 million cattle would be at risk in Texas and Florida alone.
Humans are not spared, with at least eight cases of the flies infesting people in Mexico since April.
Live animal ban
The US has responded by temporarily restricting live animal imports from Mexico. The governments of the US, Central American countries and Mexico are also working together to heighten surveillance and work towards the eradication of the New World screwworm by stepping up sterile insect releases.
Sterile male screwworm pupae (juveniles) are currently produced and safely sterilised by irradiation at a rate of over 100 million per week at a facility in Panama. This is jointly funded by the US Department of Agriculture (USDA) and Panama's Ministry of Agriculture Development. However, a successful eradication campaign may need several times this number of sterile flies.
For example, sterile fly production for releases in Mexico in the 1980s were reportedly in excess of 500 million flies per week. To combat this shortfall, the USDA is focusing releases in critical areas of Mexico and is already investing US$21 million to equip a fruit fly production facility in Metapa, Mexico, to also produce 60 million to 100 million sterile screwworm per week.
Fly production, sterilisation and release is a long process, and a reduction in wild screwworm populations would not be immediate. History has shown us that integrated control with anti-parasitic veterinary medicines are essential to repel flies and treat infestations as they arise.
Surveillance with trained personnel is also essential but is a great challenge due to an entire generation of veterinarians, technicians and farmers who have no living memory of screwworm infestations.
Finally, climate warming means that we may not be blessed with the cool weather that facilitated previous eradication, and further work is needed to determine how this will impact current eradication plans.
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
The Independent
4 hours ago
- The Independent
World now in ‘crunch time' to avoid higher levels of warming, UN scientists warn
UN scientists have warned that the world is in 'crunch time' to avoid higher levels of warming beyond the key threshold of 1.5C but that drivers of climate change are 'all moving in the wrong direction'. In their annual report, a team of more than 60 international scientists have put together a comprehensive picture of the current state of the climate and calculated the human-driven factors behind the changes the world is experiencing. It comes as part of efforts to provide regular updates between landmark UN Intergovernmental Panel on Climate Change (IPCC) reports, the last of which was published in 2021 and the next of which is expected in 2028. The group examined the amount of planet-heating carbon dioxide (CO2) the world can release into the atmosphere in the coming years while limiting warming to the UN target of 1.5C. The report estimates that the remaining 'carbon budget' for 1.5C is emitting 130 billion tonnes of C02 from the beginning of 2025, if the world is to have a 50% chance to stay within the threshold. However, this budget will be exhausted in little more than three years at current levels of CO2 emissions, according to the findings published on Wednesday night in the journal Earth System Science Data. This means that without drastic cuts to emissions, the world will be unable to prevent warming from surpassing the dangerous threshold, which will lead to a rise in extreme weather events, climate-related disasters and increase the risk of triggering irreversible changes. The report also warned the carbon budget for 1.6C or 1.7C could also be exceeded within nine years, which will significantly intensify these impacts. The scientists' long-term estimates show current average global temperatures to be 1.24C higher than in pre-industrial times. Professor Joeri Rogelj, research director at the Grantham Institute, said: 'Under any course of action, there is a very high chance that we will reach and even exceed 1.5C and even higher levels of warming. '1.5C is an iconic level but we are currently already in crunch time… to avoid higher levels of warming with a decent likelihood or a prudent likelihood as well and that is true for 1.7C, but equally so for 1.8C if we want to have a high probability there.' But Prof Rogelj added that reductions in emissions over the next decade can still 'critically change' the rate of warming and limit the magnitude and the extent by which the world exceeds 1.5C. 'It's really the difference between just cruising through 1.5C towards much higher levels of 2C or trying to limit warming somewhere in the range of 1.5,' he said. Piers Forster, professor of Climate Physics at the University of Leeds, who has helped author IPCC reports, said the report highlights how climate policies and pace of climate action 'are not keeping up with what's needed to address the ever-growing impacts'. 'I certainly tend to be an optimistic person but if you do look at this year's annual update, things are all moving in the wrong direction,' he said. 'They're not only moving in the wrong direction, we're seeing some unprecedented changes.' Reflecting on the IPCC reports, he said: 'What we had hope to see by this time is these emissions beginning to turn a corner and unfortunately that hasn't occurred.' Instead emissions have increased year on year since the 2021 report, remaining at all-time highs, he said. This year's update covers key climate system indicators such as greenhouse gas emissions and concentrations, Earth energy imbalance, human-induced climate change, remaining carbon budgets and maximum land surface temperatures. But for the first time, the annual update also included sea-level rise and global land precipitation. In 2024, the best estimate of observed global surface temperature rise was 1.52C, of which 1.36C can be attributed to human activity, caused by global greenhouse gas emissions, the scientists said. The report said last year's high temperatures are 'alarmingly unexceptional' as the combination of human-driven climate change and the El Nino weather phenomenon push global heat to record levels. While global average temperatures exceeded 1.5C for the first time, this does not mean the world has breached landmark UN agreement, which would require average global temperatures to exceed the threshold over multiple decades. When analysing longer-term temperature change, the scientists' best estimates show that between 2015 and 2024 average global temperatures were 1.24C higher than in pre-industrial times, with 1.22C caused by human activities. Elsewhere, the report found that human activities were found to be affecting the Earth's energy balance, with the oceans storing about 91% of the excess heat, driving detrimental changes in every component of the climate system, including sea level rise, ocean warming, ice loss, and permafrost thawing. Between 2019 and 2024, global mean sea level also increased by around 26mm, more than doubling the long-term rate of 1.8mm per year seen since the turn of the twentieth century. Dr Aimee Slangen, research leader at the NIOZ Royal Netherlands Institute for Sea Research, said the rise is already having an 'outsized impact' on low-lying coastal areas, causing more damaging storm surges and coastal erosion. 'The concerning part is that we know that sea-level rise in response to climate change is relatively slow, which means that we have already locked in further increases in the coming years and decades,' she said. IPCC's last assessment of the climate system, published in 2021, highlighted how climate change was leading to widespread adverse impacts on nature and people. Professor Rogelj said: 'Every small increase in warming matters, leading to more frequent, more intense weather extremes. 'Emissions over the next decade will determine how soon and how fast 1.5C of warming is reached. They need to be swiftly reduced to meet the climate goals of the Paris Agreement.'
Daily Mail
5 hours ago
- Daily Mail
Time is running out to curb climate change: Window to avoid 1.5°C of warming will close in just 3 YEARS if CO2 emissions continue at current rate, scientists warn
Time is running out to curb climate change, scientists have warned in a major new report. There are now only 130 billion tonnes of carbon dioxide left in the 'carbon budget' - the amount of carbon that can be emitted before the world hits the critical limit of 1.5°C of warming. If the world keeps producing greenhouse gases at the current rate, that will be gone in just three years. What's more, the remaining carbon budget to avoid 1.6°C or 1.7°C of warming will be burnt through in as little as nine years at current rates. The report found that 2024 experienced 'alarmingly unexceptional' high temperatures, reaching 1.52°C (2.74°F) warmer than the pre-industrial benchmark. Overall, 1.36°C (2.45°F) of that warming can be directly traced back to human activity, with the remaining 0.16°C (0.29°F) coming from natural fluctuations. A single year above 1.5°C of warming doesn't mean that the Paris Agreement has been breached, but it does show that the world is getting dangerously close to this threshold. Professor Joeri Rogelj, co-author and climate scientist at Imperial College London, says: 'The window to stay within 1.5°C is rapidly closing. Emissions over the next decade will determine how soon and how fast 1.5°C of warming is reached. ' The annual Indicators of Global Climate Change study combines the work of 60 scientists to measure 10 key indicators of climate change to give a broad picture of the planet's health. The data shows that we are rapidly approaching the warming limits set out by the Paris Climate Agreement and that the remaining 'carbon budget' is dwindling. Professor Rogelj explains that the carbon budget is worked out from the basis that 'the global warming we experience is largely determined by the total amount of carbon dioxide that is ever emitted into the atmosphere by human activities.' He adds: 'That means that if we want to keep warming from exceeding a specific level, there is a limited amount of carbon dioxide that can ever be emitted. 'The remaining carbon budget estimates how much of that amount remains when looking at where we stand today.' By looking at current warming rates and how much the planet warms per tonne of CO2 emitted, the researchers calculated that 130 billion more tonnes of CO2 will bring humanity to the 1.5°C limit set out in the Paris Agreement. At the current rate, the world releases the equivalent of around 53 billion tonnes each year. To put that into perspective, that is the same as 5.2 million Eiffel Towers of CO2 being pumped into the atmosphere every single year. What is the carbon budget? The carbon budget is an estimate of how much more CO2 can be released into the atmosphere before the world reaches a certain heating threshold. This is worked out from the basis that almost all of the world's heating is caused by CO2 added to the atmosphere. By looking at how much CO2 has been emitted and how much the planet has warmed, researchers calculate how much warming a tonne of CO2 creates. Comparing this to our current warming rates, scientists calculate how many more tonnes of CO2 would lead to a set temperature. The carbon budget for 1.5°C of warming currently stands at 130 billion tonnes from the beginning of 2025. If emissions are not rapidly reduced to more sustainable levels, there will be no way to avoid exceeding 1.5°C and triggering more severe and dangerous consequences. Even though 2024 was more than 1.5°C hotter than the pre-industrial average, that does not mean the Paris Agreement has been breached. This international treaty binds its signatories to 'pursue efforts to limit warming to 1.5°C' taken as an average over several decades. But, looking at the climate on a wider time scale shows that we are quickly approaching a time when this will be breached. The average surface temperature on Earth for the decade between 2015 and 2024 was 1.24°C (2.23°F) hotter than it was before the industrial revolution. Professor Rogelj told MailOnline that 'all' of this change is due to humans putting more greenhouse gases in the atmosphere. The study found that only 0.02°C (0.04°F) of warming over the last decade has any non-human causes, which Professor Rogelj calls a 'negligible' amount. By comparison, during the transition out of the last Ice Age - one of the fastest periods of natural warming in the planet's history - the warming rate was about 1.5°C (2.7°F) per thousand years. That is equivalent to just 0.02°C (0.04°F) of warming per decade, compared to 1.22°C (2.2°F) of human-caused warming per decade today. As greenhouse gas emissions continue to rise, the rate of heating is increasing right up to the present day. The rate of global heating seen between 2012 and 2024 was double that seen in the 1970s and 1980s. At these rates, the researchers estimate the world will breach the Paris Agreement's limits on average warming by around 2030. This is already causing measurable changes in Earth's climate, especially in the oceans which absorb 91 per cent of the excess heat trapped by greenhouse gases. Warmer waters lead to rising sea levels, faster ice melt, and more violent storms. Dr Aimée Slangen, research leader at the NIOZ Royal Netherlands Institute for Sea Research, says: 'Since 1900, the global mean sea level has risen by around 228 mm. 'This seemingly small number is having an outsized impact on low-lying coastal areas, making storm surges more damaging and causing more coastal erosion, posing a threat to humans and coastal ecosystems. Most of the excess heat created by greenhouse gases is absorbed by the oceans which leads to rising sea levels and increased ice melt 'The concerning part is that we know that sea-level rise in response to climate change is relatively slow, which means that we have already locked in further increases in the coming years and decades.' The researchers behind the report say that action needs to be taken to reduce the rate of greenhouse gas emissions to avoid more severe effects of climate change. Professor Rogelj concludes: 'How much carbon budget we have depends on the level of warming that we want to limit global warming to, and how much risk of higher warming we are willing to allow. 'Overall, however, for any temperature limit that aims to avoid dangerous levels of climate change, it essential that we stop emitting climate pollution as soon as we can. 'Every year that reductions are delayed adds to this cumulative problem.' THE PARIS AGREEMENT: A GLOBAL ACCORD TO LIMIT TEMPERATURE RISES THROUGH CARBON EMISSION REDUCTION TARGETS The Paris Agreement, which was first signed in 2015, is an international agreement to control and limit climate change. It hopes to hold the increase in the global average temperature to below 2°C (3.6°F) 'and to pursue efforts to limit the temperature increase to 1.5°C (2.7°F)'. It seems the more ambitious goal of restricting global warming to 1.5°C (2.7°F) may be more important than ever, according to previous research which claims 25 per cent of the world could see a significant increase in drier conditions. The Paris Agreement on Climate Change has four main goals with regards to reducing emissions: 1) A long-term goal of keeping the increase in global average temperature to well below 2°C above pre-industrial levels 2) To aim to limit the increase to 1.5°C, since this would significantly reduce risks and the impacts of climate change 3) Governments agreed on the need for global emissions to peak as soon as possible, recognising that this will take longer for developing countries 4) To undertake rapid reductions thereafter in accordance with the best available science
The Guardian
6 hours ago
- The Guardian
Only two years left of world's carbon budget to meet 1.5C target, scientists warn
The planet's remaining carbon budget to meet the international target of 1.5C has just two years left at the current rate of emissions, scientists have warned, showing how deep into the climate crisis the world has fallen. Breaching the target would ramp up the extreme weather already devastating communities around the world. It would also require carbon dioxide to be sucked from the atmosphere in future to restore the stable climate in which the whole of civilisation developed over the past 10,000 years. The carbon budget is how much planet-heating CO2 can still be emitted by humanity while leaving a reasonable chance that the temperature target is not blown. The latest assessment by leading climate scientists found that in order to achieve a 66% chance of keeping below the 1.5C target, emissions from 2025 onwards must be limited to 80bn tonnes of CO2. That is 80% lower than it was in 2020. Emissions reached a new record high in 2024: at that rate the 80bn tonne budget would be exhausted within two years. Lags in the climate system mean the 1.5C limit, which is measured as a multi-year average, would inevitably be passed a few years later, the scientists said. Scientists have been warning for some time that breaching the 1.5C limit is increasingly unavoidable as emissions from the burning of fossil fuels continue to rise. The latest analysis shows global emissions would have to plummet towards zero within just a few years to have any decent chance of keeping to the target. That appears extremely unlikely, given that emissions in 2024 rose yet again. However, the scientists emphasised every fraction of a degree of global heating increases human suffering, so efforts to cut emissions must ramp up as fast as possible. Currently, the world is on track for 2.7C of global heating, which would be a truly catastrophic rise. The analysis shows, for example, that limiting the rise to 1.7C is more achievable: the carbon budget for a 66% chance of keeping below 1.7C is 390bn tonnes, which is about nine years at the current rate of emissions. 'The remaining carbon budgets are declining rapidly and the main reason is the world's failure to curb global CO2 emissions,' said Prof Joeri Rogelj, at Imperial College London, UK. 'Under any course of action now, there is a very high chance we will reach and even exceed 1.5C and even higher levels of warming.' 'The best moment to have started serious climate action was 1992, when the UN [climate] convention was adopted,' he said. 'But now every year is the best year to start being serious about emissions reduction. That is because every fraction of warming we can avoid will result in less harm and suffering, particularly for poor and vulnerable populations, and in less challenges to living the lives we desire.' Rogelj said it was crucial that countries commit to big emissions cuts at the UN Cop30 climate summit in November. The hottest year on record was 2024, fuelled by increasing coal and gas burning, and setting an annual average of 1.5C for the first time. There is no sign yet of the transition away from fossil fuels promised by the world's nations at Cop28 in Dubai in December 2023. Sign up to Down to Earth The planet's most important stories. Get all the week's environment news - the good, the bad and the essential after newsletter promotion Solar and wind energy production is increasing rapidly and has precluded previous worst-case scenarios of 4-5C of global heating. But energy demand is rising even faster, leading to more fossil fuel burning and turbo-charging extreme weather disasters. The analysis, produced by an international team of 60 leading climate scientists, is an update of the critical indicators of climate change and is published in the journal Earth System Science Data. It aims to provide an authoritative assessment, based on the methods of the Intergovernmental Panel on Climate Change, but published annually unlike the intermittent IPCC reports, the most recent of which was 2021. The study found that the Earth's energy imbalance – the excess heat trapped by the greenhouse effect – has risen by 25% when comparing the past decade with the decade before. 'That's a really large and very worrying number,' said Prof Piers Forster, at the University of Leeds, UK, and lead author of the study. 'I tend to be an optimistic person. But things are not only moving in the wrong direction, we're seeing some unprecedented changes and acceleration of the heating of the Earth and sea level rise.' Sea level rise has doubled in the past 10 years, compared with the period 1971-2018, the analysis found, rising to 4mm per year. The flooding of coasts will become unmanageable at 1.5C of global heating and lead to 'catastrophic inland migration', a study in May found. Sea level is rising because about 90% of global heating is absorbed by the oceans, making the water expand, and because the climate crisis is melting glaciers and ice caps. Dr Karina Von Schuckmann, at Mercator Ocean International, said: 'Warmer waters also lead to intensified weather extremes, and can have devastating impacts on marine ecosystems and the communities that rely on them. In 2024, the ocean reached record values globally.'
