Malaria evades the Human Body's Immune system

It’s known that malaria causes a highly inflammatory response in infected individuals that leads to the deadly clinical complications of anemia and cerebral disease.

The Yale research team learned that the parasites produce their own version of a human cytokine, or immune hormone, which directs the inflammatory response during malaria.

They also discovered that this cytokine, called PMIF, incapacitates the anti-malaria, memory T-cell immune response.

Using a genetically modified strain of the malaria parasite in mice, the Yale team found that PMIF causes host T-cells to develop into short-lived effector cells rather than protective memory cells.

The short-lived cells die during the infection, and the long-lived memory T-cells are not produced in adequate numbers to combat the infection or to protect from re-infection, which occurs repeatedly in malaria-endemic regions.

“These findings indicate that malaria parasites actively interfere with the development of immunological memory, and may account for the inhibition of protective immune responses in human malaria,” said Rick Bucala, M.D., professor of internal medicine, pathology, and epidemiology and public health at Yale School of Medicine.

• “This knowledge will help us identify specific therapies that can protect anti-malarial T-cells from death and improve an individual’s immune response to infection or to vaccination.”

More information: PNAS paper: www.pnas.org/conte… ull.pdf+html

Malaria treatment: Impact on disease risk for babies

The UK NHS Information Video is very good at explaining Malaria infections and preventative actions you can take, but it does not go into details of how it affects young women, pregnant women and young breast-feeding mothers.

Recent research has indicated that Mothers who receive treatment for malaria infection could pass on lower levels of natural immunity to their babies.

Edinburgh University experts found mice treated with malaria infection drugs before they became pregnant passed on fewer antibodies to their young.

Full-blown malaria gives the immune system the chance to produce protective antibodies to pass on.

However, it is thought the drug treatment shortens the process.

The mothers benefit while children's immunity is decreased, putting them at greater risk.

The researchers said their results highlighted the need to look at how treatment might be tailored most effectively for women and their babies.

Malaria affects millions of people worldwide, mainly in developing countries. One child dies from the disease in Africa every minute.

Dr Vincent Staszewski, of Edinburgh University's school of biological sciences, said: "How an infection plays out in an individual can impact on the immunity of the next generation.

"Some treatments against disease before or during pregnancy might be beneficial for maternal health but impair infant survival."

The study, published in Proceedings of the Royal Society B, was funded by the Wellcome Trust and the Royal Society.

Malaria in Fossilised Bat Flies encased in Amber - research Paper

Background

Both sexes of bat flies in the families Nycteribiidae and Streblidae (Diptera: Hippoboscoidea) reside in the hair or on the wing membranes of bats and feed on blood.

Members of the Nycteribiidae transmit bat malaria globally however extant streblids have never been implemented as vectors of bat malaria.

The present study shows that during the Tertiary, streblids also were vectors of bat malaria.

Results

A new haemospororidan, Vetufebrus ovatus, n. gen., n. sp., (Haemospororida: Plasmodiidae) is described from two oocysts attached to the midgut wall and sporozoites in salivary glands and ducts of a fossil bat fly (Diptera: Streblidae) in Dominican amber.

The new genus is characterised by ovoid oocysts, short, stubby sporozoites with rounded ends and its occurrence in a fossil streblid.

This is the first haemosporidian reported from a streblid bat fly and shows that representatives of the Hippoboscoidea were vectoring bat malaria in the New World by the mid-Tertiary.

Conclusions

This report is the first evidence of an extant or extinct streblid bat fly transmitting malaria.

Discovering a mid-tertiary malarial parasite in a fossil streblid that closely resembles members of a malarial genus found in nycteribiid bat flies today shows how little we know about the vector associations of streblids.

While no malaria parasites have been found in extant streblids, they probably occur and it is possible that streblids were the earliest lineage of flies that transmitted bat malaria to Chiroptera.

Vetufebrus ovatus n. gen., n. sp. (Haemospororida: Plasmodiidae) vectored by a streblid bat fly (Diptera: Streblidae) in Dominican amber

Malaria Found in Blood Sucking Bug Fossilised in Amber

Researchers from Oregon State University (OSU) have discovered the fossil of a blood-sucking vampire bat fly, in the La Búcara mine - which is located in the Cordillera Septentrional mountain range of the Dominican Republic.

The researchers discovered the tiny insect frozen in amber (fossilised tree sap). The fossil is between 20 and 30 million years old.

Incidentally, the scientists also found the bat fly was carrying a strain of the malaria disease; this provides evidence that the disease may have existed even 20 million years ago.

"Bat flies are a remarkable case of specific evolution, animals that have co-evolved with bats and are found nowhere else," said George Poinar, a Professor of Zoology at OSU.

The researchers also stressed that bat flies were not common creatures and that not every bat feeds on blood.

Nevertheless, the species is widespread, with different animals appearing at different places around the world.

"Bats are mammals that go back about 50 million years, the only true flying mammal, and the earliest species had claws and climbed trees," Poinar added.

"We now know that bat flies have been parasitising them for at least half that time, and they are found exclusively in their fur. They are somewhat flat-sided like a flea, allowing them to move more easily through bat fur," he concluded.

Blood-Sucking Bat Fly Fossil Discovered in Amber

Researchers from Oregon State University (OSU) have discovered the fossil of a blood-sucking vampire bat fly, in the La Búcara mine - which is located in the Cordillera Septentrional mountain range of the Dominican Republic.

The researchers discovered the tiny insect frozen in amber (fossilised tree sap). The fossil is between 20 and 30 million years old.

Incidentally, the scientists also found the bat fly was carrying a strain of the malaria disease; this provides evidence that the disease may have existed even 20 million years ago.

"Bat flies are a remarkable case of specific evolution, animals that have co-evolved with bats and are found nowhere else," said George Poinar, a Professor of Zoology at OSU.

The researchers also stressed that bat flies were not common creatures and that not every bat feeds on blood.

Nevertheless, the species is widespread, with different animals appearing at different places around the world.

"Bats are mammals that go back about 50 million years, the only true flying mammal, and the earliest species had claws and climbed trees," Poinar added.

"We now know that bat flies have been parasitising them for at least half that time, and they are found exclusively in their fur. They are somewhat flat-sided like a flea, allowing them to move more easily through bat fur," he concluded.

Malaria: Cell Phone Cameras Capture Microscopic Images

Smart phone apps can help you check your vision, keep tabs on your blood-glucose levels and track your blood pressure. Earlier this year the U.S. Food and Drug Administration even approved an app that allows doctors to view scans on an iPhone or iPad to help them make diagnoses on the go.

But fancy apps aside, the cameras on these devices and others can help health care workers in remote or understaffed areas submit photos of complicated conditions to doctors who can verify or make a diagnosis.

One question that quickly surfaces is whether cell phone cameras are good enough to transmit microscopic information to experts.

A new study found that many simple bar phones with cameras could snap a good enough picture through a standard microscope to allow a remote assessment of a sample. The results were published online Wednesday in PLoS ONE.

“Poor and vulnerable populations are most affected by weak laboratory services because they carry the largest burden of ill health,” noted the researchers behind the study, which was led by Coosje Tuijn, of the Royal Tropical Institute of Biomedical Research in Amsterdam.

And although microscopy is often pivotal in diagnosing common diseases, such as malaria, tuberculosis and other bacterial or parasitic diseases, in poor areas, “microscopy services are often suboptimal,” the researchers noted.

And “as a result, many common diseases are misdiagnosed and improperly treated, ” which can affect patients—and cost the health system time and money.

In Uganda, where there are only eight physicians for every 100,000 people, getting a definitive diagnosis can be difficult. The research team enlisted local health workers to try using their own (or borrowed) cell phones to capture photos and videos of microscopic images to send off for remote diagnosis.

The best images were obtained with cameras that were two megapixels or higher, which are common in smart phones and are in some slimmer Nokia, Samsung and Sony bar phones.

And some of the most successful diagnoses were those of samples that contained malaria parasites, which “were often so clear that specific stages of the malaria parasite could be identified”—thus improving targeted treatment.

TB was a little more challenging (owing to the small size of its bacteria) and required a fluorescent microscopy and a five-megapixel camera.

But phones with video could also grab clips that revealed some other microbes as they moved around, helping to improve the remote diagnosis.

Once the pictures were snapped, health workers could send them directly to a website that could make them accessible to experts for diagnosis and/or students for training.

Direct feedback, via phone call or text, could then be sent to the user’s phone.

Malaria: Prevention by Blocking Cell’s Passage

Researchers at the Wellcome Trust Sanger Institute have discovered an understanding on how the most deadly species of malaria parasite, Plasmodium falciparum, invades human red blood cells.

They used the technique called Avidity-based Extracellular Interaction Screen (AVEXIS), which discovered the interaction between the parasite protein and the host receptor.

The parasite relies on a single receptor on the red blood cell's surface to invade, offering an exciting new focus for vaccine development.

The blood stage of Plasmodium's lifecycle begins when the parasite invades human red blood cells, and it is this stage that is responsible for the symptoms and mortality associated with malaria.

"Our research seems to have revealed an Achilles' heel in the way the parasite invades our red blood cells. It is rewarding to see how our techniques can be used to answer important biological problems and lay the foundations for new therapies," senior co-author Gavin Wright said in a statement.

However, researchers demonstrated that disrupting this interaction completely blocked the parasite from gaining entry into the red blood cell. Importantly, this was true across all parasite strains tested, making it appear that the receptor is a universal entry pathway. It is hoped that the parasite's dependency on this one protein can now be exploited to develop new and effective vaccines.

Malaria kills approximately one million people every year, mostly children under the age of five in sub-Saharan Africa. Researchers have tried for many years to develop a vaccine to prevent the parasite gaining entry into our red blood cells, but so far they have been unsuccessful.

One of the challenges is that the parasite is adaptable - although several red blood cell receptors had been previously identified, none was shown to be essential: when entry through one receptor is prevented, the parasite is able to switch to another. This new research has found a single receptor that is absolutely required by the parasite to invade.

"The discovery of a single receptor that can be targeted to stop the parasite infecting red blood cells offers the hope of a far more effective solution," Investigator at the Jenner Institute, Adrian Hill, said.

According to the Health Protection Agency, malaria is not endemic in the UK, but in the five years between 2006 and 2010, almost 1600 cases have occurred every year on average in travellers returning to or arriving in the UK from malaria-endemic countries.

Malaria vaccine has potential to save millions

After more than 30 years of work, researchers have for the first time succeeded in creating a vaccine against malaria, a deadly disease that kills nearly 800,000 a year, most of them children.

The experimental vaccine, still in the testing phase, only protects about 50% of children who receive it, but even that could "potentially translate into tens of millions of cases of malaria in children averted annually," says Tsiri Agbenyega, the principal investigator for the vaccine trials at Agogo Presbyterian Hospital in Agogo, Ghana.

"This is remarkable when you consider there has never been a successful vaccine against a human parasite nor against malaria."

Malaria is one of the most devastating diseases on the planet. Half the world's population is at risk of malaria. There are about 225 million cases yearly and more than 780,000 deaths, according to the World Health Organization. In Africa, one in five children die from malaria, one every 30 seconds, WHO says.

The vaccine was tested on 15,460 children in two age groups, 6 to 12 weeks old and from 5 to 17 months of age in seven African countries.

It was given in three doses. In children 5 to 17 months, the vaccine was 50% protective against the Plasmodium falciparum malaria parasite, which is carried by mosquitoes. Results in children 6 to 12 weeks old will be released in 2012.

Researchers hope to improve the effectiveness of the vaccine over time, but even at 50% effectiveness it means that for every 1,500 children vaccinated, 750 won't get malaria, says Andrew Witty, the CEO of GlaxoSmithKline, one of the vaccine's developers. "This is a very meaningful start."

Not all vaccines are 100% effective, even in the United States, says William Schaffner, chair of the Department of Preventive Medicine at Vanderbilt University School of Medicine in Nashville.

For example, the meningitis vaccine given to teens "doesn't have the staying power we anticipated it would, so we have to give a booster." But they still prevent disease and will be "great stimulus for further work."

The vaccine may be available in Africa "perhaps as early as 2015," Witty says.

The project is a collaboration between GlaxoSmithKline, the PATH Malaria Vaccine Initiative and the Bill & Melinda Gates Foundation.

It is being funded in part by more than $200 million in grants from the Bill & Melinda Gates Foundation and $300 million from GlaxoSmithKline.

An exact cost for the series of three vaccination is not known, but GlaxoSmithKline will supply the vaccine at the lowest possible cost, Witty says: the cost of producing it plus 5%, which will go to researching other neglected diseases. "We have no intention of making a profit," he says.

The vaccine is being produced in Europe and will go through licensing there for production and use in Africa, says Mary Hamel of the Centers for Disease Control and Prevention. It will then need to undergo market authorization for each African country.

GlaxoSmithKline says its expects the initial production capacity to be about 30 million doses, enough for 10 million children a year. It hopes to scale up manufacturing capability in both Europe and later in Africa and perhaps India, to lower costs.

The vaccine will not be available in the United States because being developed in Europe there is no way for it to undergo the Food and Drug Administration's licensing process.

The vaccine is meant to be used alongside long-proven malaria protections such as insecticide-impregnated bed nets and indoor spraying, both of which have begun to lower malaria rates in Africa in the past decade.

When both are in place "we could expect hundreds of thousands of lives to be saved," CDC's Hamel says.

The way the vaccine was developed is exciting, says Seth Berkley, CEO of the Global Alliance for Vaccines and Immunisation. In the past, such work would be done either by a government or a large company.

In an indication of the weight of expectation around this vaccine, still known only as RTS,S , the results were announced at a malaria forum in Seattle called by Bill and Melinda Gates, with World Health Organisation director general, Margaret Chan, and the UK development secretary, Andrew Mitchell, present. They were published at the same time online by the New England Journal of Medicine.

Mobile app diagnoses malaria from a single drop of blood

The virtual ink had barely dried on our story about the Skin Scan app for diagnosing melanoma when we received word of another, equally compelling mobile diagnostic tool.

Focusing this time on the millions of people at risk from malaria in sub-Saharan Africa and other parts of the world, Lifelens is a project that has created a smartphone app to diagnose the insidious, mosquito-borne disease.

More than one million people die each year from Malaria, and roughly 85 percent of them are children under the age of 5, the Lifelens project notes. The most prevalent diagnostic tool, meanwhile, is the rapid diagnostic test (RDT), which is known to be associated with a 60 percent incidence rate of false positive results.

That, in turn, results in the treatment of many people who don’t actually have Malaria, driving up the costs of anti-Malaria treatment significantly. The Lifelens project, on the other hand, aims to make the process both cheaper and more accurate by analyzing blood digitally instead.

Specifically, once blood is stained to reveal the Malaria parasites, the project’s smartphone app can analyze a magnified image of a drop of blood captured via simple finger prick, including counting the various types of cells it includes. Malarial parasites are among those it can identify, making false results much less likely.

Once analysis is complete, data is uploaded to the Web, where it can be mapped for a high-level view of where Malaria outbreaks are occurring.

The video below demonstrates Lifelens in action:

The origin of malaria: The hunt continues

The greater spot-nosed monkey, Cercopithecus nictitans. (Credit: © Jean-Louis Albert, CIRMF, Gabon)

The agent of malaria has been found in the greater spot-nosed monkey, also known as putty-nosed monkey (Cercopithecus nictitans), a small African primate derived from a line different to that of humans, gorillas and chimpanzees.

This discovery challenges current thinking on the origin of the parasite and introduces a key element in the fight against malaria: knowing how it has adapted to the human species will make it possible to target its weaknesses.

This work stems from research carried out by CNRS researchers in association with other organizations and is published on the 4 July 2011 in the journal PNAS.

Malaria, also known as paludism, is one of the greatest global scourges. This pathology, which causes a million human deaths each year, is especially rampant in Africa. The question of whether the primary infection originated from rodents or birds has long remained unanswered. Also found in gorillas, it was thought that the parasite was specific to hominids.

By working on the subject, a team of CNRS researchers headed by Franck Prugnolle and François Renaud of the Laboratoire MIVEGEC(1)(CNRS/IRD/Université Montpellier, jointly with the Centre International de Recherches Médicales de Franceville in Gabon, and in collaboration with other organizations, has demonstrated the presence of Plasmodium falciparum, the agent of malaria, in the greater spot-nosed monkey (Cercopithecus nictitans), a small African monkey derived from a line different to that of humans. The origin of the parasite probably predates the origins of the African hominids line.

The presence of Plasmodium falciparum in this Old World Monkey opens the way to the analysis of the genome of the parasite found in this species. Comparing its sequence with that (already known) of falciparum in humans will enable researchers to discover the molecular signatures of the human parasite and to find out how it has adapted to humans. Knowing the weaknesses of the parasite will be a major asset in combating malaria.

Malaria: Turning the Genetic Keys to switch it off

More than a third of the 72 molecular switches that control key stages in the life cycle of the malaria parasite can be disrupted in some way.

The finding is a significant breakthrough in the search for inexpensive, effective vaccines and drugs to stop the transmission of a disease that kills up to a million children a year, according to new research.

Until now little has been known about the cellular processes involved in the development of this deadly disease.

The research, published in the journal Cell Host & Microbe, involved the first comprehensive functional analysis of protein kinases in any malaria parasite.

It is also the largest gene knock-out study in Plasmodium berghei—a malaria parasite infecting rodents.

“Blocking parasite transmission is recognized as an important element in the global fight to control malaria,” says Rita Tewari, in the school of biology at the University of Nottingham.

“Kinases are a family of proteins which contribute to the control of nearly all cellular processes and have already become major drug targets in the fight against cancer and other diseases.

“Now we have identified some key regulators that control the
transmission of the malaria parasite. Work to develop drugs to eradicate this terrible disease can now focus on the best targets.

This study shows how systematic functional studies not only increase our knowledge in understanding complexity of malaria parasite development but also gives us the rational approach towards drug development.”

More.....

University of Nottingham: http://communications.nottingham.ac.uk/News.html

Fighting Malaria: Venderbilt and Yale Scientists Transplant the Nose of Mosquito

Scientists at Vanderbilt and Yale universities have successfully transplanted most of the "nose" of the mosquito that spreads malaria into frog eggs and fruit flies and are employing these surrogates to combat the spread of the deadly and debilitating disease that afflicts 500 million people.

The research is described in two complimentary papers, one published this week in the early online edition of the Proceedings of the National Academy of Sciences and the other which appeared online Feb. 3 in the journal Nature.

The mosquito's "nose" is centered in its antennae, which are filled with nerve cells covered with special "odorant receptors" that react to different chemical compounds. The insect ORs are comparable to analogous receptors in the human nose and taste buds on the tongue.

"We've successfully expressed about 80 percent of the Anopheles mosquito's odorant receptors in frog's eggs and in the fruit fly antennae," says Laurence Zwiebel, professor of biological sciences at Vanderbilt, whose lab performed the frog egg transplantation. The fruit-fly (Drosophila melanogaster) work was done in the laboratory of John Carlson, Eugene Higgins Professor of Molecular, Cellular and Developmental Biology at Yale.

Both accomplishments are part of a five-year project supported by the Grand Challenges in Global Health Initiative funded by the Foundation for NIH through a grant from the Bill and Melinda Gates Foundation with the goal of producing novel ways to inhibit the spread of malaria. Scientists from the Wageningen University in the Netherlands, the African Insect Science for Food and Health Institute in Kenya, Ifakara Health Institute in Tanzania and the Medical Research Council Laboratories in the Gambia are also participating in the project.

Genetic discovery by British scientists raises hopes for malaria treatments

Genetic discovery by British scientists raises hopes for malaria treatments - Times Online

The genetic code of the plant that provides the most effective treatment for malaria has been cracked by scientists, raising the prospect of cheaper and more plentiful drugs against a disease that kills about a million people each year.

The achievement by British researchers will assist the development of higher-yielding varieties of the sweet wormwood plant Artemisia annua that addresses a global shortage of the drug artemisinin and reduces its cost. New seeds could be produced using insights from the study and be available to farmers in as little as two to three years.

Artemisinin combination therapies (ACTs), in which the drug is given in combination with older anti-malarial treatments, are recommended by the World Health Organisation as the best way to fight malaria.

Artemisinin can be made only by using an acid extracted from sweet wormwood, a herb used in traditional Chinese medicine. As most of the varieties under cultivation are wild plants with low yields, demand for ACTs outstrips supply and the drugs are much more expensive than older, less-effective treatments.

High Tech Giants Fighting Against Malaria

Tech giants are putting their expertise to good use outside of the corporate arena by using IT to combat malaria by ensuring drugs are more readily available.

Dubbed SMS for Life, the solution - jointly developed by IBM, Novartis and Vodafone - is being used in association with the Roll Back Malaria Partnership, to boost availability of anti-malarial drugs in remote areas of Tanzania.

SMS for Life brings together mobiles, SMS and web-based tech to help track and manage the supply of Artemisinin-based Combination Therapy (ACT) drugs and Quinine injectables. Put together, these can greatly reduce the death toll linked to malaria, which totals almost one million people each year in Africa - most of which are young children and pregnant women.

After visits to clinics, hospitals and dispensaries across Tanzania, IBM, Novartis and Vodafone initiated a five-month pilot of the SMS for Life solution, covering 135 villages and over a million people in different geographic locations across Tanzania.

Healthcare staff receive automated text to remind them to check drug stocks every week. Then, using toll-free numbers, they can reply by text to a central UK-based database. Once stock levels are determined, deliveries can be arrange before they completely run out.

IBM interns - dubbed Extreme Blue - were heavily involved in the project, as was Vodafone's development partner MatsSoft.

“This is an example of a truly innovative solution helping solve a humanitarian problem. After spending time on the ground, we created a project plan, developed the application with Vodafone and Novartis and established the best way to deliver the pilot, working with the Tanzanian Ministry of Health," said Peter Ward, project manager for IBM, in a statement. "We expect other countries will also be able to benefit in the future.”

During the pilot benefits were clear almost immediately. Indeed, during the first few weeks, the number of locations reporting zero stock levels went down by more than 75 per cent. As a result, the authorities are considering extending the roll-out country wide.

“The SMS for Life programme has already had a positive effect in Tanzania. I've seen district medical officers ordering urgent stock replacements for various health facilities," said Winfred Mwafongo, senior health officer for Tanzania's Ministry of Health and Social Welfare, in a statement.

"During a visit to 19 rural health facilities in one district alone, I saw huge improvements in their inventory management systems. I'm very impressed with the results so far and look forward to following the rest of the pilot through to completion."

Mosquito: The Human World's Deadliest Enemy

AP/PA Photos

The mosquito rarely lives longer than a month and is not as ferocious or visually intimidating as a raging carnivore, but it comes in much more regular and intimate contact with humans, than any other dangerous creature. It also rapidly spreads deadly and contagious diseases, leading to the death of more humans, than any other member of the animal kingdom. By injecting parasites and viruses into the blood stream, the mosquito causes upwards of two million deaths a year. According to Dr. Mark Rowland of the London School of Hygiene and Tropical Medicine, malaria is responsible for 800,000 to one million of those deaths. Malaria, Elephantiasis, West Nile virus, dengue fever, yellow fever, etc are all deadly diseases that are spread by mosquitoesand there are many more. While the most dangerous breeds of the bug are local to Africa, Asia and North America, it’s still a good idea to stock up on bug repellent for those humid, mosquito-filled nights.

Malaria and Dengue on the Run

Aedes aegypti. The head is at centre right, with large compound eyes (blue). There are two hairy antennae and a long proboscis (pink) used for penetrating human skin and sucking blood (Image: Eye Of Science / SPL)" title="A coloured scanning electron micrograph (SEM) of the head of a female yellow fever mosquito, Aedes aegypti. The head is at centre right, with large compound eyes (blue). There are two hairy antennae and a long proboscis (pink) used for penetrating human skin and sucking blood (Image: Eye Of Science / SPL)">

A coloured scanning electron micrograph (SEM) of the head of a female yellow fever mosquito, Aedes aegypti. The head is at centre right, with large compound eyes (blue). There are two hairy antennae and a long proboscis (pink) used for penetrating human skin and sucking blood (Image: Eye Of Science / SPL)

Female A. aegypti feed almost exclusively on human blood (see image), and unlike most other mosquito species, it thrives in human habitats. Their larvae grow readily in water-filled plant pot plates and discarded plastic containers. Some even claim that it is more adept at avoiding well-aimed swats.

When an A. aegypti mosquito (see image) bites someone who has dengue, the virus begins replicating in the mosquito's gut. From there it spreads to the salivary gland and, 10 to 14 days after being infected, the mosquito's saliva contains enough virus to infect anyone it bites.

The aim is to combat dengue fever, a mosquito-borne disease that has reached pandemic proportions in a matter of decades. If the new approach works against dengue fever it should also work against other insect-borne diseases, including the biggest killer, malaria. That possibility has won the team developing this strategy funding through the Bill and Melinda Gates Foundation.

The potential benefits are huge, but before it can go ahead the team will have to convince people the strategy is safe. If things go wrong, it might make dengue spread even faster.

Still, the situation is already pretty bad. In south-east Asia, long plagued by dengue, outbreaks are becoming bigger, more frequent and longer lasting. In Australia, the Pacific and most of the Americas, where dengue was once rare, the disease is taking hold with a vengeance. An outbreak earlier this year that affected at least 60,000 people in Brazil and Argentina reached Buenos Aires for the first time.