Category: Bird Flu

Bird flu, avian influenza, H5N1 and other strains

Bird Flu Test

Researchers at McMaster University, Toronto, have developed a simple diagnostic that can spot all the major human respiratory viruses, including SARS.

The press release announcing this finding includes in the list of “major” viruses – H5N1 (bird flu), but H5N1 is yet to become a “major” human virus having only killed a few dozen people in the forty-odd years since it emerged! This contrasts sharply with the more common influenza type A viruses to which humans have been exposed for centuries that have killed thousands upon thousands.

Obviously, the writer of the press release wants to get the item into the media, hence the mention of H5N1 and SARS, and, admittedly, the diagnostic, which is still undergoing clinical evaluation, will be able to spot those viruses. There is enough disinformation regarding avian influenza as it is. It seems that almost any piece of viral research is likely to have some PR exploitable link to H5N1 these days, but there are two sides to every story and a lot of researchers have stated already that should H5n1 ever mutate into a human transmissable form it will lose its lethality without doubt. After all, it doesn’t kill wild birds, just that pampered stock we breed to eat.

Homeopathic Flu Remedy

It’s rather worrying to see the proliferation of books about avian influenza, as if people aren’t scared enough, but this one is more worrying still – its title alludes to the idea that homeopathy can somehow help us survive influenza epidemics and pandemics. Bizarrely, it says we can survive “past, present and future” episodes. Present and future are really pushing it, given the lack of valid trials of homeopathy in any area of medicine, but “past”?

Forget H5N1, H3N0 is a killer too

According to the People’s Daily Online, the first Vietnamese have died of H3N0 another strain of the influenza A virus, related to but different from the increasingly familiar H5N1. From the scaremongering point of view, there’s no need to hold the frontpage (at least outside Vietnam) as this strain is far less virulent than H5N1.

However, it does bring to light an aspect of flu viruses that gets little mention in the media – avian influenza has killed very few people, especially compared with the number of annual deaths from human influenza, but should any of these avian strains jump between species they are likely to lose their virulence to a great degree. One flu expert told us that, “H5N1 will surely decrease in lethality as it becomes more infectious between humans…no doubt about it.” More on that next week…

Molecular Model of Oseltamivir (Tamiflu)

tamiflu molecular structurePremier molecular modeller Stephan Logan has produced for us a timely reminder of the chemical structure of Tamiflu, the antiviral flu drug. You can order the necessary components to build the Molecular Model of Oseltamivir (Tamiflu) and other molecules from Stephan’s site. Perfect for that avian flu lecture!

In case you missed my how to avoid colds and flu article, it’s once again taking pride of place on the sciencebase site.

Flu Resistance

The international science journal Nature has lifted the media embargo on an important paper due for publication next week – The paper raises the possibility that the current prophylactic regimen for Tamiflu (oseltamivir) may have contributed to the emergence of partial resistance to the drug in a Vietnamese patient.

This paper provides an analysis of an H5N1 virus — isolated from a
patient in Vietnam earlier this year (1) – that is partially resistant to
oseltamivir.

The potential emergence of a resistant virus is a continuing concern of
health agencies, although evidence to date suggests that viruses with
mutations giving rise to resistance have reduced fitness, making them less
transmissible and of lower pathogenicity.

The paper highlights the fact that the current recommended
prophylactic treatment regimen may involve suboptimal doses and
durations of oseltamivir treatment that could contribute to the emergence
of resistant virus. It also raises the possibility that a larger arsenal
of influenza antivirals may need to be developed. Stockpiling zanamivir
(sold as Relenza) in addition to oseltamivir may be warranted.

Although the case described in this paper was part of a family cluster,
the paper does not directly address the issue of human-to-human
transmission of H5N1.

Expert offers tips on how to stay healthy during cold, flu season

As the weather turns colder, you can count on one thing: Organisations with a health expert to hand will publish a press release offering tips on how to avoid catching a cold or flu in the coming months. I spotted the first of the season on Physorg.com today announcing the anti-disease advice of Pamela Aaltonen at Purdue Uni’s School of Nursing. There’ll be an epidemic of them by the end of October, mark my words.

Emerging viral infections

Emerging viral infections: what did we learn from SARS?

This briefing document was prepared for the UK’s Royal Society in 2004, but its message seems just as relevant given the current warnings regarding avian flu and the allegedly imminent flu pandemic. Immediately after the Royal Society meeting, outbreaks of avian H5N1 disease were reported in a number of countries including Vietnam, Thailand, Laos, Cambodia, China, and Indonesia. Human cases had also been reported in Thailand, but the concern is whether human disease is been missed elsewhere. In 2005, this avian virus still poses a serious threat to human health and is one with significant implications for animal production and economies. The long-term, global implications are only just being considered. Should this incredibly virulent strain avian flu transcend the species barrier and become infectious between people we could be facing a disease far worse than SARS.

2020 UPDATE: We faced MERS after SARS and now COVID-19

Infectious threats

We are facing more and more emerging infections partly because of international travel and rising population densities, poverty, food and water insecurity, a refugee crisis, and continued interfacing between people and wildlife. Severe acute respiratory syndrome (SARS) in the winter of 2002-2003 was just a single example that has taught the international medical community, researchers, and policy makers lessons we must learn if we are to fight new, emergent infectious agents. Our hunter-gatherer ancestors were not afflicted with the likes of measles, mumps, and chicken pox. These diseases emerged as people moved more from place to place and populations rose. Environmental change too means the world has become the perfect culture medium for new pathogens.

We have, of course, benefited from two decades of disease research stimulated by HIV but we simply cannot predict the next new pathogen and must improve our understanding of spreading diseases if we are to face the next threat. Issues of preparedness, medical ethics, and civil liberties must be addressed urgently before the successor to SARS emerges.

Read David Bradley’s Report from Session 1: on how we can never conquer infectious diseases.

Will we ever conquer infection?

Reporting from a January 2004 Royal Society meeting on infectious diseases – The myth of a germ-free utopia

Thirty years ago various experts pronounced that we had conquered infectious disease; we could thank better hygiene, sterilized food, vaccines, and antibiotics. But, in recent years there has been renewed anxiety about infectious diseases, said epidemiologist Tony McMichael of the Australia National University, Canberra.

We have been confronted with the emergence of legionnaire’s disease, lyme disease, HIV/AIDS, human “mad cow” disease, ebola and hantaviruses, SARS, and many other new diseases. Old adversaries, such as tuberculosis, dengue fever, cholera, and malaria have re-emerged. Cholera is a case in point. A bacterium once confined mainly to South Asia, cholera kills thousands from Asia to Europe and from Africa to North and Latin America.

Pathogens are spreading more freely. McMichael blamed increased personal mobility, greater international trade, and ever more densely populated cities. Greater poverty, changes in sexual practices, and intravenous drug use too, coupled with intensive food production and some modern medical procedures have created many new openings for evolving microbes.

Environmental changes have affected how humans come into contact with microbes while social changes, at the individual and community level, ensure human networks, technology choices, politics, and the distribution of disadvantage all create new opportunities for infection.

McMichael argued that new circumstances lead to unusual contact between people and pathogens. Millions of years ago our descent from the trees exposed us to the savannah’s disease-bearing insects. The advent of agriculture and civilization brought us into closer contact with animal diseases than ever before. War and invasions helped nations swap these diseases, and European expansion spread them to the New World.

McMichael proposed that we are living through a fourth transition – a global transition. Demographic, environmental, behavioural, technological, and other changes in human ecology created an environment well suited for the emergence of new diseases. Injudicious modern medicine is to blame for drug resistance in opportunistic microbes. Climate change and changes in river ecosystems are also influencing infectious disease emergence and spread.

Many factors influence the emergence of infectious diseases so what is the relative importance of environmental and social factors, asked McMichael. Having failed to achieve the germ-free Nirvana, we must recognize the increasingly globalised microbial world that will continue to produce infectious surprises. Rather than use the militaristic hyperbole of a war on microbes, we must approach the topic within an ecological framework. This will help us anticipate the effects of environmental and social change and act accordingly.
Read on… Emerging Viruses