March 10, 2005
More Signs Bird Flu Is Spreading Between Humans

The World Health Organization is reporting cases where multiple members of families are testing positive for bird flu. When multiple infections occur in the same family that raises the threatening possibility that the bird flu is mutating into a form that is more capable of human-to-human transmission. The development of that capability could ignite a deadly worldwide bird flu pandemic which could potentially kill tens of millions of people. Some of the bird influenza cases being found in Vietnamese families are strongly suggestive that human-to-human transmission is taking place.

Since the family members are infected with identical or closely related H5N1, distinguishing between a common source and human transmission is heavily dependent on onset dates. Most cases show symptoms 2-4 days after exposure. Therefore, cases involving a common source will develop symptoms at about the same time. If the transmission is from one family member to another, there will be a longer time lag and the onset dates will be bimodal.

As noted above, the latest familial cluster from Thai Binh has a 7 day differential between onset dates suggesting the sister was infected by her brother.

Since primary caregivers for sick family member are most often female another sign of human-to-human transmission is the higher rate of infection of females in cases where multiple family members are diagnosed with bird flu.

However, another way to demonstrate human-to-human transmission in these other familial clusters is to simply compare the gender distribution of the primary cases relative to the secondary. There were 13 index cases in the 12 clusters (in one cluster cousins developed symptoms at the same time). There were 6 females and 7 males indicating the risk to both sexes was similar. In contrast, 11 of the 14 secondaries were female.

Why should we be alarmed by these reports? Karl Nicholson, a professor of infectious diseases at University of Leicester in Britain who currently working on bird flu vaccine development says bird flu has a very high mortality rate.

Based on the current recognized cases of the illness, it seems to have an 80% mortality rate, says Nicholson.

Imagine a virus with such a high mortality rate mutating to become easily transmissible between humans.

However, the mortality rate from bird flu may be overstated due to cases that are not diagnosed.

The World Health Organization said Tuesday that seven Vietnamese patients who initially tested negative for bird flu have been found to be carrying the virus after their samples were retested.

All seven, who were first tested in January, have since recovered, said WHO regional spokesman Peter Cordingley.

Still, even if some of the current estimate for bird flu mortality rate is overstated it is very unlikely to be overstated by, say, a full order of magnitude.

A recent case with a Vietnamese male nurse is another possible case of human-to-human bird flu transmission.

A 26-year-old male nurse from northern Vietnam who provided bedside care for a 21-year-old bird flu patient now in critical condition has himself tested positive for H5N1 avian influenza, according to media reports from the region.

It is possible the nurse was exposed to the patient's blood or mucus. It is not clear that the nurse got the virus from the patient and even if he did it is not clear that the virus was transmitted by a route that would mean the virus has developed greater ability to move between people.

Whether or not these cases indicate the avian flu is now more able to spread between humans the virus is still over there moving through duck, chicken, and other bird populations. It may still mutate into a massive killer pandemic.

Should the bird flu break out into the general population keep in mind that in my past posts I've listed things we ought to do to reduce our risks of getting the flu in the case of a killer pandemic. If I don't turn out to be one of the early victims when the pandemic starts I'll colllect together all those items and you all can then read my comprehensive list of things you ought to do and ought not do.

One thing you ought to do now: Tell your government to accelerate the development of better flu vaccine production technologies so that when a killer pandemic eventually shows up in the human population we will be able to more quickly and massively manufacture vaccines.

Share |      Randall Parker, 2005 March 10 01:37 PM  Dangers Natural Bio


Comments
Leigh said at March 10, 2005 4:49 PM:

Looks to me like the hazard from the Bird Flu pandemic is only going to become severe if the virus mutates into a less virulent form AND becomes more transmissible.

My logic: Extremely virulent diseases can "burn-out" their available hosts. If we are actually seeing 80% mortality... seems to me that even in health-care challenged countries they are going to get a good handle on case-tracing and care. It seems apparent that the victims are extremely debilitated very quickly and don't seem to have much opportunity to spread the flu on to that many other social contacts before they either die or recover.

What would be scary would be if the Bird Flu becomes more transmissible and less virulent. I would say the reason normal flu is so common is that the symptoms are not debilitating enough to keep the host bedridden. They don't feel "bad enough" to stay home or not work, so they go forth and spread the virus. With the Bird Flu... people stop, drop and/or die or recover. As long as it's this deadly, it's not going to spread much.

Just my opinion. Take it for what you paid for it.

Robert Silvetz said at March 10, 2005 5:50 PM:

Well, this is definitely not encouraging news. Minor things that may help.

Ozone generators -- upregulate lung defenses and of course, tends to kill anything airborne

Hydrogen peroxide (diluted) to the mucous membrane as the first hint of trouble (e.g the sneeze, the suden post-nasal drip) -- reactive oxygen species tend upregulate surface chemistry in the defensive direction

L-arginine -- NO is part of the primary defense mechanism by the epithelium against virus. If you up your pure L-arginine uptake (with a little ornithine keto glutarate to prevent ammonia headaches), beyond having a better sexual experience, your epithelium will have plenty of NO to tackle virus. Oh and it will drop your blood pressure as well, so if you are a low blood pressure this not for you.

Bob Badour said at March 12, 2005 5:30 PM:

Leigh,

I failed to see anything suggesting bird flu sufferers drop in their tracks even at an 80% mortality. In fact, the part of Randall's post stating it seemed one sibling contracted the disease 7 days after the other sibling suggests to me one might remain ambulatory for quite some time before becoming bedridden.

If the disease continues on its course of increasing transmissability, I find that very worrisome. A worker might continue to go to work for the first 6 of the disease infecting everyone and by day 8 or 10, the place might have no workers left.

Currently, the only thing preventing that scenario seems to be the weak transmissibility requiring close contact for an extended period.

candra said at December 1, 2005 11:58 AM:

what can the bird flu do to the little kids if the get it. can they get hurt more than the older people.

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