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Avian flu: strictly for the birds

MagazineJanuary 2006 (Vol. 16 Issue 10)Avian flu: strictly for the birds

W e are all in the grip of avian-flu hysteria

W e are all in the grip of avian-flu hysteria. The World Health Organization (WHO) estimates that the virus could claim up to 7.4 million lives around the world if it successfully mutates and becomes transmissible among humans, while the UK's chief medical officer Sir Liam Donaldson says it's a matter of when and not if.

When it happens, it could claim the lives of up to 750,000 Britons, he estimates while, in America, it may kill up to two million people, warns President Bush.

While there are many types of avian, or bird, flu, the disease strain that is worrying health officials is the influenza A (H5N1) virus, first discovered in a flock of terns in South Africa in 1961.

While H5N1 is usually strictly for the birds, a case of infection among humans was first reported in 1997, during an outbreak in poultry in Hong Kong. It caused a severe respiratory illness in 18 people, killing six. Since then, human infections have been reported in Thailand, Vietnam and Cambodia during major H5N1 outbreaks in poultry. Around half the infected humans have died.

Outbreaks among poultry have become common, especially in Southeast Asia and, this year, cases have been reported in poultry farms in Europe. Domesticated poultry catch H5N1 from wild birds, which carry the viruses in their intestines.

As far as researchers have been able to establish, virtually all of the human cases have occurred among poultry workers who had direct contact with the birds or with infected areas. Poultry workers who work among domesticated chickens, ducks and turkeys are at risk because the virus can be passed to humans via the birds' faeces.

Several cases have been reported where a sufferer has been able to infect another person but, so far, there is no evidence that it has been passed on beyond a limited contact group. Officials at the Ministry of Public Health in Thailand reported a typical example in 2004. It involved a poultry worker who had become infected, and who then transmitted it on to her mother and aunt who came to care for her at her hospital bedside. The mother died of pneumonia after being at her daughter's side for 18 hours; the aunt also developed pneumonia, but survived. Both were found to have the H5N1 virus (N Engl J Med, 2005; 352: 333-40).

In both these cases, the viral infection was transmitted only after extended exposure.

Another study, carried out at the National Pediatric Hospital in Hanoi, Vietnam, showed that it is not highly infectious. Researchers at the hospital questioned 83 staff members, all of whom had been exposed to four confirmed cases of H5N1 infection; of the staff, just two, or 2.4 per cent, were possibly infected with the avian flu virus (Emerg Infect Dis, 2005; 11: 210-5).

So far, it's been reckoned that the H5N1 virus has killed around 65 people over eight years. To put this in perspective, around half a million people die of seasonal flu every year, including 40,000 Americans and 12,000 Britons (Drugs, 2004; 64: 2031-46).

Why is an epidemic predicted?
Why should scientists suddenly fear that the H5N1 virus is likely to mutate soon, and become transmissible among humans, when it has been around for at least 50 years?

There appears to be no scientific basis for the dramatic public warnings that are being issued. One reason given is the rising number of outbreaks in poultry farms around the world, and the increased exposure to humans.

But scientists also point to the cyclical nature of viruses. The world seems to be hit by a major flu pandemic three or four times a century. The major epidemic of the last century was the Spanish flu outbreak that occurred in the United States during 1918-19, killing 40 million people. There were also flu pandemics in 1957 and in 1968 - and the WHO has pencilled in 2005-06 as the date for the next outbreak.

However, 40 years elapsed between the first flu pandemic of the 20th century and the second, followed by 10 years between the second and third - which can hardly be viewed as a predictive pattern.

Scientists made similar warnings over the SARS (severe acute respiratory syndrome) virus in 2003, which was also expected to become a major pandemic. Like H5N1, it started in Asia before spreading to the West, where it seemed set to reach Canada. The Canadian health authorities - so concerned by the threat - allowed the United Nations and the WHO to take over the day-to-day responsibility for controlling any outbreak.

In the event, SARS proved to be a damp squib, killing fewer than a thousand people worldwide.

Why flu drugs don't work
All flu viruses change antigenically to evade recognition by the host's immune system. These modifications take place rapidly and often - a flu virus can mutate up to a million times more often than a DNA virus (Vaccine, 2002; 20: 3068-87). Vaccine designers at the WHO Global Influenza Program have to prepare new antigen formulations every year, often nine months ahead of the next major flu outbreak. Their role is therefore mainly predictive as they try to second-guess what the new flu virus strain will be to achieve a perfect antigenic match. Only the vaccine that is a perfect match to the virus can combat it, and achieving this is almost impossible, given the infinite permutations that the virus can undergo (Lancet, 2005; 366: 1139-40).

Ironically, and not surprisingly, the perfect flu vaccine is always a year too late.

Over the past 40 years, the drug industry has produced four major antiviral drugs to combat flu - amantadine in 1966, rimantadine in 1993, zanamivir in 1999, and oseltamivir, marketed as Tamiflu, also in 1999 - and resistance to all four is regularly reported (Lancet, 2000; 355: 827-35; J Infect Chemother, 2003; 9: 195-200).

The hope, therefore, that any one of these can combat a virus that has not even crossed over into humans is futile. And yet, Tamiflu is consistently promoted as the main weapon against the H5N1 virus. The US government has placed an order for 20 million doses at a cost of $2 billion (USA Today, October 8, 2005), while the UK government is ordering 14.6 million doses, even though America's advisors at the Centers for Disease Control and Prevention (CDC) in Atlanta, GA, have gone on record as stating that there is no vaccine to protect people against the H5N1 virus (www.cdc.gov/flu/avian/gen-info/facts.htm).

Protecting against avian flu
At its worst, the avian flu has killed fewer than half the number of poultry workers who have been infected, according to WHO statistics. However, if it truly is as lethal as we have been warned, it surely should have eventually killed everyone it infects. This suggests that a healthy body, and a properly functioning immune system, can withstand any viral attack.

* Supplements

- Vitamin A is one of the most important nutrients for establishing a healthy immune system. It helps maintain the surface tissues that line the eyes as well as the respiratory, urinary and intestinal tracts which, in turn, act as physical barriers against bacteria and viruses (Clin Infect Dis, 1994; 19: 489-99; J Nutr, 1995; 125: 1211-21).

It also helps to regulate the immune system by enabling lymphocytes - the white blood cells that fight infection and disease - to do their job more effectively.

Vitamin A is found in cod liver oil, which is also rich in vitamin D, and meat, oily fish, cheese, and whole milk and eggs, which are also rich sources of retinol, the active form of vitamin A.

Taken as a supplement, an effective dose is between 8000-12,0000 IU/day.

- Vitamins C and E, which are antioxidants like vitamin A, are also well established as immune-system enhancers. Vitamin E is especially effective for reducing susceptibility to infections (Arch Immunol Ther Exp, 1987; 35: 207-10).

A dose of around 200-400 IU/ day of vitamin E, and 1000 mg/day of vitamin C, is recommended to boost the immune system.

- Zinc is another potent antiviral. In one study, a zinc nasal gel significantly reduced the duration of a cold (Ear Nose Throat J, 2000; 79: 778- 80). The more popular zinc lozenges appear to be less effective (J Am Med Assoc, 1998; 279: 1962-7).

- Echinacea is supposed to be one of the most effective immune boosters among the herbal remedies, although the hard science to back the claims of its advocates is inconclusive (Arch Farm Med, 1998; 7: 541-5). Like zinc, Echinacea seems to be at its most effective if taken during the first hours of infection (J Fam Pract, 1999; 48: 628-35).

- Hydrastis canadensis, or goldenseal, is another herbal standby but, again, the science behind it does not support its high reputation.

- Andrographis paniculata, or Kalmegh, an Ayurvedic remedy, is a more effective herbal that has been successfully tested against placebo in two studies (Phytomedicine, 2000; 7: 341-50).

- Elderberry is an effective antidote to the flu. In one study, 60 flu victims took either 15 mL of elderberry extract or a placebo, four times a day for five days. The elderberry relieved symptoms four days earlier than did the placebo (J Int Med Res, 2004; 32: 132-40).

- Phytolacca americana, or pokeweed, is another herb that is known to stimulate the immune system - and it's especially effective against flu viruses (Antimicrob Agents Chemother, 1980; 17: 1032-3), although it can be toxic if taken over the long term.

* Exercise

- Regular, moderate exercise is good for improving immune function (Exerc Immunol Rev, 1997; 3: 32-52). But bursts of heavy exercise may have the opposite effect, and can suppress the immune system for several hours, thereby increasing the chances of an upper respiratory tract infection (Int J Sports Med, 1994; 15: S131-41). It's worthwhile noting that the soldiers who were most badly affected by the swine flu outbreak of 1976 were just beginning their basic combat training, a time of exceptional exertion (J Infect Dis, 1977; 136: S363-8).

* Stress

- High stress levels probably have the single most important influence over the state of the immune system (J Fla Med Assoc, 1993; 80: 409-11). This was shown in a study where the participants - half of whom were proven to have high stress levels, the other half with low stress levels - were all exposed to rhinoviruses, the viruses responsible for the common cold. Only 27 per cent of those in the low-stress group developed symptoms, compared with 47 per cent of the high-stress group (N Engl J Med, 1991; 325: 606-12).

* Prescription drugs

- You are much more likely to develop the flu if you are taking a prescription drug. Antibiotics can enhance flu susceptibility (J Am Med Assoc, 1997; 278: 901-4), including flucloxacillin (Med J Aust, 1989; 151: 701-5) and Septrin (trimethoprim, sulphamethoxazole) (Br J Dermatol, 1987; 116: 241-2).

* Homeopathy
In France, where homeopathy is firmly established, the two most popular flu remedies are both homeopathic preparations: Oscillococcinum 200 and L.52 Lehning.

-Oscillococcinum, a combination of Anas Barbariae, Hepatis and Cordis, has been shown to be an effective antidote against the worst symptoms of flu, such as coughing, fever, shivering, and muscle and joint stiffness (Br J Clin Pharmacol, 1989; 27: 329-35).

- L.52 Lehning, a combination comprising 10 active homeopathic ingredients, has been proven to be more effective than a placebo (Casanova PA et al. L.52: A Flu Treatment, by Dr Ph Lecocq. Metz: Editions Lehning, 1988).

Bryan Hubbard


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