Imported New World screw-worm fly myiasis

In mid-August 2012, Pamela (not her real name), a university lecturer, visited the Amazon rainforest in north-eastern Peru to conduct a mammal survey, watching and recording wildlife, for a week. She also owned a small sheep farm in Victoria. She had no pre-existing comorbidities.

During her stay in Peru she noticed increasing soreness and a slight discharge behind her right ear. While flying back to Australia, Pamela felt that “things” were moving in a hole behind her right ear, where intense pain was felt intermittently.

Upon arrival in Melbourne, she presented to The Travel Doctor clinic, suspecting that she might have contracted myiasis. On examination, there was an open cavity of about 1 cm in diameter behind her right pinna, filled with maggots wriggling in serous fluid (Box, A). The diagnosis of wound (rather than dermal) myiasis was immediately obvious.

Twenty-three live larvae were extracted from the cavity. After the procedure, the pain subsided significantly and the wound healed within 12 days. At the Victorian Infectious Diseases Reference Laboratory, the maggots were identified as larvae of Cochliomyia hominivorax, the New World screw-worm fly (NWSF). All containers used for transport and storage were autoclaved and destroyed as biological waste.

Human cutaneous myiasis is typically furuncular and confined to dermal tissues. For example, the larvae of the African tumbu and South America bot flies form characteristic localised lesions, each containing one maggot.1 However, typical of wound myiasis, this infection was much deeper, containing multiple larvae.1 NWSF larvae can typically burrow to a depth of 4 cm, producing large cavities as seen in this case.2 The NWSF is attracted to wounds to lay eggs. Unlike most other species of blowflies, adult female screw-worms lay their eggs at the edges of wounds on living, injured mammals.2 Pamela underwent a minor facelift in January 2012, with gathered epithelial tissue behind her ears. Pamela’s site of infection was most likely an abrasion on the skinfold from a hatband.

The main diagnostic feature was the presence of dark pigmentation of the dorsal tracheal tubes extending over 2–3 segments at the posterior end (Box, B).2 The larvae were in the third instar and close to maturity (Box, C).2 Full development takes 5–7 days, after which they fall to the ground to pupate.2

The range of the NWSF is restricted to Central and South America.1,2 Before major eradication campaigns, it extended from the southern states of the United States to Argentina. The NWSF is exotic to Australia and suspicion of infestation in animals is notifiable under state and territory animal health legislation.3 By contrast, screw-worm fly infestation in humans is not notifiable.4

Although the results of surveillance corroborate a low likelihood of incursion into Australia,5 with large feral animal populations in the north and large numbers of livestock along the eastern seaboard, there is a significant possibility of the screw-worm fly becoming established if it manages to gain entry into Australia.6–8

Biosecurity practices and prompt recognition and reporting of an incursion (Emergency Animal Disease Watch Hotline, 1800 675 888),5,9 are critical to Australia’s preparation for screw-worm flies and other exotic diseases and pests. Pamela’s case reinforces that the risk for Australia is real.

Box –
Wound myiasis from New World screw-worm fly infestation

A: Open cavity behind the patient’s right pinna, filled with maggots. B: Larvae (third instar) of Cochliomyia hominivorax. The main diagnostic feature was the dark pigmented dorsal tracheal tubes at the posterior end of the larvae. C: Larva (third instar) of C. hominivorax. The hook-like mouthpart (on the left) of a live larva constantly strikes with a digging movement inside the host tissue.

[Articles] Changes in health in England, with analysis by English regions and areas of deprivation, 1990–2013: a systematic analysis for the Global Burden of Disease Study 2013

Health in England is improving although substantial opportunities exist for further reductions in the burden of preventable disease. The gap in mortality rates between men and women has reduced, but marked health inequalities between the least deprived and most deprived areas remain. Declines in mortality have not been matched by similar declines in morbidity, resulting in people living longer with diseases. Health policies must therefore address the causes of ill health as well as those of premature mortality.

[Editorial] Primary care is a team sport

Physicians are often called the gatekeepers of primary care, describing the providers at the front lines who orchestrate the steps in the cascade of care. Primary care is the first stop to connect patients—especially those with complex health needs, such as multiple chronic illnesses—with other necessary services, including specialists, after hours or home care, and social services. But a rising number of patients at risk for chronic diseases, an ageing population, and life-prolonging medical interventions have added new financial and capacity stresses on primary care systems, with primary care physicians making decisions from an increasingly challenging position.

[Correspondence] Tackling preventable diseases in Yemen

The health-care system in Yemen has deteriorated since the start of the war in March, 2015. Impairment exists at all levels of health services; from improper function of health-care facilities to a shortage of basic and life-saving needs, such as drugs, water, and fuel. This continuous, unresolved crisis has led to a rise in preventable diseases and other health problems, such as infectious diseases, malnutrition, diarrhoea, and unnecessary organ loss.1,2

[Perspectives] Salmaan Keshavjee: tackling tuberculosis (without rocket science)

Salmaan Keshavjee’s CV is a puzzling document. A first degree in biochemistry from Queen’s University in Ontario, Canada, is followed by a move to the USA and a master’s in immunology and infectious diseases from the then Harvard School of Public Health. The next 5 years find him still at Harvard, but now doing a course in Middle Eastern Studies, and then writing a doctoral thesis in anthropology. 3 years on he’s graduating from Stanford University, this time with a medical degree. Is this a man who can’t make up his mind?

[Health Policy] Will Ebola change the game? Ten essential reforms before the next pandemic. The report of the Harvard-LSHTM Independent Panel on the Global Response to Ebola

The west African Ebola epidemic that began in 2013 exposed deep inadequacies in the national and international institutions responsible for protecting the public from the far-reaching human, social, economic, and political consequences of infectious disease outbreaks. The Ebola epidemic raised a crucial question: what reforms are needed to mend the fragile global system for outbreak prevention and response, rebuild confidence, and prevent future disasters? To address this question, the Harvard Global Health Institute and the London School of Hygiene & Tropical Medicine jointly launched the Independent Panel on the Global Response to Ebola.

[Comment] Opening the GATE to inclusion for people with disabilities

For more than an estimated billion people with disabilities,1 assistive technologies are crucial mediators for realising people’s rights, and for promoting access and empowerment—the theme of the International Day of Persons with Disability for this year (Dec 3, 2015). By 2050, the number of older (aged over 60 years) people will have increased, worldwide, from about 840 million in 2013 to more than 2 billion, many of whom will also need assistive technology to remain independent.2 Some older people will need several assistive products, as will the increased proportion of people living with chronic diseases.

Why we can trust scientists with the power of new gene-editing technology

A summit of experts from around the world is meeting in Washington to consider the scientific, ethical and governance issues linked to research into gene editing. Convened in response to recent advances in the field, the summit includes experts from the US National Academy of Science, the UK’s Royal Society and the Chinese Academy of Science.

Gene editing is a new technique that allows one to change chosen genes at will. It has been applied to many organisms but a recent report from China showing the modification of human embryos using a technology known as CRISPR/Cas9 mediated editing set alarm bells ringing.

Here’s the main fear: if you modify an embryo (and therefore also its germline), you change not only the person that embryo will become but also its future sons, daughters, grandsons and granddaughters.

Since we don’t know much about this technology, it’s right to stop and think about it. But personally I’m not overly concerned: we’ve been here – or somewhere quite like it – before.

Learning from history

In 1975, scientists met at Asilomar on the Californian coast to discuss a moratorium on recombinant DNA (that’s DNA formed from combining constituents from different organisms).

Alarm bells had started ringing when scientists realised they could combine the DNA from a monkey virus with a circle of DNA called a plasmid, carrying an antibiotic resistance gene purified from the human gut bacteria, Escherichia coli (E. coli).

This cocktail sounded dangerous and scientists discussed a voluntary moratorium on certain experiments, as well as sensible guidelines for containing recombinant material within laboratories.

Why we can trust scientists with the power of new gene-editing technology - Featured Image

Horizontal gene transfer occurs in nature when DNA is carried between species by viruses and related carriers.
Jer Thorp/Flickr, CC BY

Regulations and guidelines are still in place and after 40 years few, if anyone, has been harmed by recombinant DNA. And there have been no reported outbreaks of recombinant material that have significantly affected human health or the environment.

All technologies, including different agricultural practices, have upsides and downsides, and most medicines and treatments have side effects. But recombinant DNA would now have to be classed among the least dangerous of scientific developments.

Understanding science

One reason the technology has proven so safe may be that genetic recombination has been going on for millions of years. In most cases, genes are simply passed on from parent to child. But horizontal gene transfer also occurs in nature when DNA is carried between organisms or even species by viruses.

Over time, DNA is naturally swapped around and moved. Though you may have eaten transgenic plant products, I very much doubt you’ve noticed.

There was a fear “mad scientists” would invent dangerous new superbugs and killer viruses. Perhaps this could have happened, but sadly there are enough pre-existing dangerous substances and naturally occurring diseases, which have been perfected by evolution, out there already. So germ warfare scientists are more likely to just use them.

Another fear was that researchers would modify humans. Most countries quickly outlawed the modification of human germ cells and, to my knowledge, it has never occurred. In general, scientists seem to have obeyed the regulations.

But another reason is that it has proved difficult to introduce new genes into mammalian cells. It’s legal to modify human cells, such as blood stem cells, to cure genetic diseases. But human cells are among the hardest to modify. Human “anti-viral” software seems so powerful that it inhibits the stable insertion and expression of new DNA.

The promise of gene editing

I’m sure you’ve met people who’ve had their teeth straightened or undergone cosmetic surgery. But you’ve probably never met anyone who’s had gene therapy or ever seen a transgenic animal.

Could that change with gene editing? Gene editing is so precise that one doesn’t just lob in a new gene and hope it works; what one does is edit the existing gene to eliminate any misspellings, introduce beneficial natural variants, or perhaps cut out or insert new genes into chosen locations.

Our anti-viral software may not even detect what’s happened. And provided there aren’t any “off-target’” effects, where we hit the wrong gene, there may be no or minimal side effects.

Now that it’s so easy to meddle in human genes, why shouldn’t we worry?

The new technology is a game-changer – but it’s not a runaway phenomenon, like releasing cane toads, blackberries or rabbits into Australia. After 40 years, there have been few, if any problems, with genetically modified organisms. And the experiments – though much easier now – are still so elaborate and expensive that the technology will spread slowly.

We’ll likely remain cautious about modifying human embryos and about any modification that may be passed on to the next generation. To date, consent is required for all treatments. And while patients may opt for experimental cancer therapy or surgery, we always try to think carefully when others, who cannot consent, will be affected.

Some people will even ask why it’s wrong to correct a defect that could haunt future generations. Or, if we could introduce a gene variant that protects people from cancer – such as creating a duplication of the tumour suppressor gene p53 – why wouldn’t we want that for our children?

Genetics is a branch of science that’s ripe for discussions, and conversations on recombinant DNA, gene therapy, cloning and stem cells have all gone well. Guidelines have been sensible and researchers have largely complied with them.

The very fact that people from across the world are gathering to discuss the issues surrounding the latest breakthroughs in gene technology is a very strong sign that the science will be used responsibly. One hopes that the concurrent meeting on climate change in Paris is also a victory for science.

Merlin Crossley, Dean of Science and Professor of Molecular Biology, UNSW Australia. This article was originally published on The Conversation. Read the original article. Main photo: Libertas Academica/Flickr

Other doctorportal blogs

Govts doing little to tackle climate health threat

Picture: paintings%20/%20Shutterstock.com“>paintings / Shutterstock.com

More than half of governments around the world are yet to develop national plans to protect their citizens from the health effects of climate change despite increasing warnings it will cause more extreme weather, spread disease and put pressure on food and water supplies.

As leaders from around the world meet in Paris for UN climate talks, an international survey of 35 countries, including Australia, has found a general lack of focus and urgency around the looming threat of climate change to health, with most governments doing little work on likely effects and how to mitigate them.

The survey results underline calls from the AMA, the World Medical Association and other national medical organisations for the health effects of climate change to be made a priority at the climate talks.

AMA President Professor Brian Owler said that while much of the Paris talks will be about carbon emission targets, there should be equal emphasis on equipping health systems to cope with the extra burden of problems created by climate change.

“Climate change will dramatically alter the patterns and rate of spread of diseases, rainfall distribution, availability of drinking water and drought,” Professor Owler said. “The incidence of conditions such as malaria, diarrhoea and cardio-respiratory problems is likely to rise.”

He said the Paris Conference was “the perfect place” to develop and implement plans to deal with these effects.

The AMA President’s comments came as a survey coordinated by the World Federation of Public Health Associations (WFPHA) found almost 80 per cent of governments are yet to comprehensively assess the threat climate change poses to the health of their citizens, two-thirds had done little to identify vulnerable populations and infrastructure or examine their capacity to cope, and less than half had developed a national plan.

The result underlines the importance of repeated AMA calls for the Federal Government to do much more to prepare for the effects of climate change, which Professor Owler said were “inevitable”.

Earlier this year the AMA released an updated Position Statement on Climate Change and Human Health that warned of multiple risks including increasingly frequent and severe extreme weather events, deleterious effects on food production, increased pressure on scarce water resources, the displacement of people and an increase in health threats such as vector-borne diseases and climate-related illnesses.

“There are already significant health and social effects of climate change and extreme weather events, and these effects will worsen over time if we do not take action now,” Professor Owler said.

“Nations must start now to plan and prepare. If we do not get policies in place now, we will be doing the next generation a great disservice.

“It would be intergenerational theft of the worst kind — we would be robbing our kids of their future.”

In May, the AMA and the Australian Academy of Science jointly launched the Climate change challenges to health: Risks and opportunities report that detailed the likely health effects of climate change and called for the establishment of a National Centre of Disease Control to provide a national and coordinated approach to threat.

The WFPHA said the results of its survey, released little more than two weeks before the United Nations Climate Change Conference in Paris, should serve as a wake-up call for governments to do much more.

“The specifics of these responses provide insight into the lack of focus of national governments around the world on climate and health,” the Federation said.

Disturbingly, the survey found that Australia was one of the laggards in addressing the health effects of climate change, having done little to assess vulnerabilities and long-term impacts, develop an early warning system or adaptation responses, and yet to establish a health surveillance plan.

On many of these measures, the nation was lagging behind countries like the United States, Sweden, Taiwan, New Zealand and even Russia and China.

Climate and Health Alliance Executive Director Fiona Armstrong, who helped coordinate the survey, said the results showed the Federal Government needed to place far greater emphasis on human health in its approach to climate change.

“As a wealthy country…whose population is particularly vulnerable to the health impacts of climate change, it is very disappointing to see this lack of leadership from policymakers in Australia,” Ms Armstrong said.

Public Health Association of Australia Chief Executive Officer Mike Moore said the increasing number and ferocity of bushfires and storms underlined the urgent need for action.

“It is time to ensure that health-related climate issues are part of our national planning and budgeting if we are to pre-empt many avoidable illnesses and injuries,” Mr Moore said.

The AMA’s Position Statement on Climate Change and Human Health can be viewed at: position-statement/ama-position-statement-climate-change-and-human-health-2004-revised-2015

Adrian Rollins

[Comment] Primary health care and the Sustainable Development Goals

After the eight Millennium Development Goals that have shaped progress in the past 15 years, 17 Sustainable Development Goals (SDGs) were adopted by governments at the UN General Assembly in September, 2015. SDG3 explicitly relates to health—to “Ensure healthy lives and promote well-being for all at all ages”. This goal is translated into 13 targets: three relate to reproductive and child health; three to communicable diseases, non-communicable diseases, and addiction; two to environmental health; and one to achieving universal health coverage (UHC).