Infectious Disease Compendium

Influenza

Microbiology

A virus. There is A, B and C. Influenza is brought to you by the alphabet.

And besides the human strain, various bird influenzas (H7N9)(PubMed) are just waiting to jump to humans and kill us.

Epidemiologic Risks

Breathing next to someone with influenza. It is also spread by contaminated hands and, in an experiment I would not participate in, through the eye when sprayed in the face. So wear a mask with eye protection. Highly infectious.

One poster demonstrated that infected patients can spew infectious influenza at least 6 feet with a cough (Ref).

We are still waiting for the next pandemic, either avian or human, to sweep the world and kill large numbers of humans. Don't kid yourself. It will happen.

How long are people infectious? With H1N1, and allow me to quote "Of 43 persons with PCR-confirmed pandemic (H1N1) 2009 from whom a second specimen was collected on day 8, 74% remained PCR positive and 19% were culture positive. If the 73 symptomatic household members without PCR- confirmed illness are assumed to have pandemic (H1N1) 2009, a minimum of 8% (6/73) of case-patients shed replicating virus on day 8. Self-isolation only until fever abates appears insufficient to limit transmission (PubMed)."

14% of them what have detectable seasonal influenza by PCR can be asymptomatic but have low viral loads (PubMed) and are probably not that infectious. Still, do not lick their nose.

The effects of the flu vaccine are wide ranging, depending on the population studied: decreased infection, decreased hospitalization, decreased transmission and decrease in stroke and heart attack. While efficacy hovers around 50%, its benefits are undeniable to everyone except the Atlantic and the Cochrane review.

And healthcare worker vaccination is associated with decreased flu death in patients (PubMed).

Worried about that coughing idiot on the plane? "Passengers were at 3.6% increased risk of contracting pandemic (H1N1) 2009 if they sat in the same row as or within 2 rows of persons who were symptomatic preflight. A closer exposed zone (2 seats in front, 2 seats behind, and 2 seats either side) increased the risk for postflight disease to 7.7%" (PubMed). But wearing a mask on the plane is protective (PubMed) and a lot easier than holding your breath for the entire flight.

Be wary of pigs. Pigs at fairs may have influenza A and not be ill, although I am uncertain how to tell is a pig is ill and they do not like wearing N95 masks (PubMed).

Syndromes

When flu first hit Europe 500 years ago it was called the 'gasping oppression' (PubMed). I think we should still use the term

High fevers, headache, severe cough, way bad myalgias. Whether or not you die may be due to a genetic predisposition (PubMed).

For H1N1, it is the obese (of 92 case patients who died (17%), 56 (61%) had BMI ≥30 and 28 (30%) had BMI ≥40 (PubMed) and the pregnant who are likely to die.

Face masks and hand hygiene reduces respiratory illnesses in shared living settings like dorms (PubMed).

Secondary bacterial pneumonias are very common with influenza, including the 2009 H1N1: "Of 3,110 (29.3%) samples positive for pandemic (H1N1) 2009 virus, 28% contained >1 other pathogen, most commonly Staphylococcus aureus (14.7%), Streptococcus pneumoniae(10.2%), and Haemophilus influenzae (3.5%)(PubMed)". They are more likely to have not been on prior antivirals, to go septic and to die (PubMed). Your threshold for adding antibacterial should, as a result, be low.

Pregnancy and obesity are risk factors for dying from influenza; with H1N1, about 6% had a vascular thrombotic event (PubMed).

If you are a HCW, you can protect yourself and other with vaccination and proper PPE. You know, wear a mask around coughing patients. The risk?

"For patients exposed to at least 1 contagious HCW compared with those with no documented exposure in the hospital, the RR of HA-ILI was 5.48; for patients exposed to at least 1 contagious patient, the RR was 17.96; and for patients exposed to at least 1 contagious patient and 1 contagious HCW, the RR was 34.75 (PubMed)." But I presume those that do not use PPE have lots of children and syphilis, being too dense to understand contraception.

Besides acute influenza and secondary infections, flu is associated in increased risk of MI (PubMed), stillbirths, smaller babies, dumber babies, and acute worsening of chronic medical problems.

Treatment

Zanamivir or oseltamivir (92% of influenza is now resistant to amantadine and rimantadine).

If you think a little is good than a lot is better: wrong. When it comes to oseltamivir, more only increases cost and toxicity without clinical benefit (PubMed).

Also, nitazoxanide 600 mg twice daily for 5 days was associated with a decrease in duration of symptoms in patients with acute uncomplicated influenza by about a day (PubMed).

Treatment of flu will decrease the symptoms by a day and in the severely ill decrease the risk of dying. Usually given within 48 hours, but quasi-benifical effects can occur up to 5 days in some populations (PubMed).

Severe H1N1 may be associated with a IgG subclass 2 deficiency (PubMed).

In nursing home outbreaks (2 or more) start universal chemoprophylaxis in less than five days: "LTCFs that initiated chemoprophylaxis >5 days after outbreak onset had significantly longer duration of outbreaks (18.3 vs. 6.7 days; ), higher incidence rates (10.5 cases per 100 residents vs. 6.2 cases per 100 residents; ), and higher case-fatality rates (3.3 deaths per 100 residents with influenza A vs. 0.45 deaths per 100 residents with influenza A; ) than did LTCFs that initiated chemoprophylaxis 5 days after outbreak onset" (PubMed)."

Steroids did nothing for severe H1N1 except INCREASE mortality. I guess that is not nothing (PubMed).

There is a vaccine which, if you are a dumb ass, you might avoid. The vaccine is reasonably effective, overall it decreases the risk of flu about 50%.

The high dose flu vaccine for the elderly decreases the risk 24% compared to the standard dose vaccine.

Being immune to influenza leads to less influenza, less secondary infections, less death from flu and its complications, fewer cardiovascular events (PubMeds), fewer strokes (PubMed) less loss of pregnancy (1 in 10 pregnancies were lost in the 1918 pandemic), and the birth of larger, smarter, wealthier babies. Really. Although, as is always the case, there is contradictory data (PubMed).

Not only is the vaccine safe in pregnancy, it decreases disease in mom and in the baby after delivery.

The H1N1 vaccine did not increase the risk of Guillian-Barre even a hair of a whit and the disease has 15 x the GBS rates as the vaccine (PubMed). The data all suggests the risk of GBS from the disease is far worse than the vaccine (Review).

If you think, after reading the steaming pile that is the Annals, that Maxingshigan– Yinqiaosan is of utility, see my SBM analysis of that farce.

Oscillococcinum? You are joking right? Do you know what that is?

"In to a one litre bottle, a mixture of pancreatic juice and glucose is poured. Next a Canard de Barbarie is decapitated and 35 grams of its liver and 15 grams of its heart are put into the bottle. Why liver? Doctor Roy writes: “The Ancients considered the liver as the seat of suffering, even more important than the heart, which is a very profound insight, because it is on the level of the liver that the pathological modifications of the blood happen, and also there the quality of the energy of our heart muscle changes in a durable manner.”

After 40 days in the sterile bottle, liver and heart autolyze (disintegrate) into a kind of goo, which is then “potentized” with the Korsakov method where the glass containing the remedy is shaken and then just emptied and refilled", and the process of filling and emptying is repeated 200 times. If you were cleaning a glass in the sink how any times short of 200 would you rinse the glass before declaring everything gone and the glass clean?

"Moreover, at "200C" (or "200K" or "200 CK") the concentration of the original substance would be 1 part in 100200 ;which is a 1 followed by 400 zeroes. A 1 followed by 100 zeroes is called a googol. The estimated number of particles in the universe that we can see is a googol, give or take a few zeroes. So in order for one of the original molecules to be present in a container of Oscillococcinum, the mass of that container would have to be about a googol googol googol times our world, which would be incomprehensibly larger than the visible universe."

If you really think that could possibly have any effect on influenza, I worry for your grasp on reality.

Notes

The downstream complications of influenza are not inconsequential: worsening of cardiopulmonary diseases, more vascular events like MI (PubMed) and increased focal and bloodstream bacterial infections (PubMed). Flu season is bad for pregnant females: increased stillbirth and smaller, perhaps stupider, children.

Influenza is particularly deadly in the pregnant female: more hospitalizations from flu, increased mortality and smaller children. Early treatment is associated with better outcomes (Pubmed).

Get the damn vaccine, you fool. Anyone who can take the vaccine and doesn't is a moron. Period. End of story.

You can't get the flu from the vaccine (its dead) and it will not protect you from the 1000 and one viruses out there that are not influenza. But it will prevent you and, more importantly, your patients, from dying from not only influenza but community acquired pneumonia as well (PubMed). Few medical interventions provide more bang for the buck.

The vaccine lasts the whole season. It is a myth that there is a significant decline in antibody over the flu season (PubMed).

The vaccine is safe and effective in HIV-positive patients, patients with cancer, and transplant recipients but not as effective as in Immunocompetent (Pubmed)

And there is no such thing as a stomach flu. God, that irritates me.

Prior post vaccination Guillain Barre Syndrome is NOT a risk for subsequent GBS (PubMed).

A few words about the Swine flu. Eat bacon. It will decrease the spread of the disease. Do not rely upon the rapid test, it is only useful if positive (MMWR). So far it kills mostly kids and pregnant females as a significant number of adults born before 1950 have preexisting cross reacting antibody from strains circulating before 1950. So far it is sensitive to oseltamivir. and early use in at risk populations increases survival. That will not last. Many of the deaths are due to bacterial superinfections and, with all the MRSA circulating in the US as well, I expect a fair number of deaths from MRSA as it is not an organism I can treat. I sure hope it does not 'mate' with H5N1 and we end up with a highly infectious and highly virulent influenza A. And get the damn vaccine; given that we have a near perfect match between the vaccine and the H1N1 it should be highly efficacious in preventing H1N1.

Avian influenza: the H5N1 strain that is slowly sweeping across the world. Currently (12/23/06) only those that have close contact with ill birds are at risk. This is due to the fact that human receptors for H5N1 are only in the lower respiratory tract; therefore you need to snort in a big load of virus to get infected. IF it mutates to acquire an affinity for upper airway human receptors and IF it retains its virulence, it is estimated it will kill 68 million world wide. Treatment would be zanamivir or oseltamivir (resistance increasing as the organism moves across the world) if you could get it in fast enough. I am not optimistic that should the time come for human to human spread we will be able to diddley.

People say they have the quote flu unquote when in fact they have another of the innumerable viruses that cause a febrile or coughing illness. Real flu makes you sicker than stink. Doctors also use the term too freely: stomach flu for example. Stop it. Precision of thought is demonstrated with precision of speech. I will let someone else comment of precision of writing.

I reproduce here my yearly Medscape blog entry, A Budget of Dumb Asses:

This essay is, I would like to clarify, directed at healthcare providers, not patients.  Healthcare providers have no excuse to avoid the flu vaccine: they have access to the world's medical knowledge and should be able to rise above superstition and ignorance.  The data is reasonably clear: HCW vaccination decreases patient death (PubMed).

Yes, I too am a Dumb Ass, but for different reasons.

I give you, slightly rewritten for 2011, a Budget of Dumb Asses.

I wonder if you are one of those Dumb Asses who do not get the flu shot each year? Yes. Dumb Ass. Big D, big A. You may be allergic to the vaccine (most are not when tested), you may have had Guillain-Barre, in which case I will cut you some slack. But if you don't have those conditions and you work in healthcare and you don't get a vaccine for one of the following reasons, you are a Dumb Ass.

1. The vaccine gives me the flu. Dumb Ass. It is a killed vaccine. It cannot give you the influenza. It is impossible to get flu from the influenza vaccine.

2. I never get the flu, so I don't need the vaccine. Irresponsible Dumb Ass. I have never had a head on collision, but I wear my seat belt. And you probably don't use a condom either. So far you have been lucky, and you are a potential winner of a Darwin Award, although since you don't use a condom, you are unfortunately still in the gene pool.

3. Only old people get the flu. Selfish Dumb Ass. Influenza can infect anyone, and the groups who are more likely to die of influenza are the very young, the pregnant, and the elderly. Often those most at risk for dying from influenza are those least able, due to age or underlying diseases, to respond to the vaccine. You can help prevent your old, sickly Grandmother or your newborn daughter from getting influenza by getting the vaccine, so you do not get flu and pass it one to her. Flu, by the way, is highly contagious, with 20% to 50% of contacts with an index case getting the flu.  However, Granny may be sitting on a fortune that will come to you, and killing her off with the flu is a great way to get her out of the way and never be caught.  That would make a good episode of CSI.

4. I can prevent influenza or treat it by taking echinacea, vitamin C, oOscillococcinum or Airborne. Gullible Dumb Ass cubed then squared. None of these concoctions has any efficacy what so ever against influenza. And if you think oscillococcinum has any efficacy, I would like you to invest in a perpetual motion machine I have invented.  None of the above either prevent or treat influenza. And you can't "boost" your immune system either. Anyone who suggests otherwise wants you money, not to improve your health.

5. Flu isn't all that bad of a disease. Underestimating Dumb Ass. Part of the problem with the term flu is that it is used both as a generic term for damn near any viral illness with a fever and is also used for a severe viral pneumonia. Medical people are just as inaccurate about using the term as the general public. The influenza virus directly and indirectly kills 20,000 people  (depending on the circulating strain and year) and leads to the hospitalization of 200,000 in the US each year. Influenza is a nasty lung illness. And what is stomach 'flu'? No such thing.

6. I am not at risk for flu. Denying Dumb Ass. If you breathe, you are risk for influenza. Here are the groups of people who should not get the flu vaccine (outside of people with severe adverse reactions to the vaccine): Former President Clinton, who evidently doesn't inhale. Michele Bachmann. Wait, that's the HPV vaccine.  And people who want to be safe from zombies. If you don't get the vaccine you do not have to worry about the zombie apocalypse, because zombies eat brains.

7. The vaccine is worse than the disease. Dumb Ass AND a wimp. What a combination. Your mother must be proud. Unless you think a sore deltoid for a day is too high a price to pay to prevent two weeks of high fevers, severe muscles aches, and intractable cough.

8. I had the vaccine last year, so I do not need it this year. Uneducated Dumb Ass. Each year new strains of influenza circulate across the world. Last year's vaccine at best provides only partial protection. Every year you need a new shot. 

9. The vaccine costs too much. Cheap Dumb Ass. The vaccine costs less than a funeral, less than Tamiflu, and less than a week in the hospital.

10.  I received the vaccine and I got the flu anyway.  Inexact Dumb Ass. The vaccine is not perfect and you may have indeed had the flu.  More likely you called one of the many respiratory viruses (viri?) people get each year the flu.  Remember there are hundreds of potential causes of a respiratory infection circulating, the vaccine only covers influenza, the virus most likely to kill you and yours.

11. I don't believe in the flu vaccine.  Superstitious, premodern, magical thinking Dumb Ass. What is there to believe in?  Belief is what you do when there is no data. Probably don't believe in gravity or germ theory either. Everyone, I suppose, has to believe in something, and I believe I will have a beer.

12. I will wait until I have symptoms and stay home. Dangerous Dumb Ass.  Despite often coming to work ill, especially second year residents, about 1 in 5 cases of influenza are subclinical, hospitalized patients are more susceptible to acquiring influenza from HCW's than the general population,  and 27% of nosocomial acquired H1N1 died. And you will never realize that you were the one responsible for killing that patient by passing on the flu. 

13. The flu vaccine is not safe and has not been evaluated for safety.  Computer illiterate Dumb Ass.  There are 1342 references on the PubMeds on safety of the flu vaccine, and the vaccine causes only short term, mild reactions.  All health care requires weighing the risks of an intervention against the benefits. For the flu vaccine all the data suggests huge benefit for negligible risk. And as a HCW, it could be argued that we have a moral responsibility to maximize the safety of our patients.

14. The government puts tracking nanobots in the vaccine as well as RFID chips as part of the mark of the beast, and the vaccine doesn't work since it is part of a big government sponsored conspiracy to keep Americans ill, fill hospital beds, line the pockets of big pharma and inject the American sheeple with exotic new infections in an attempt to control population growth and help usher in a New World Order. Well, that excuse is at least reasonable. Paranoid Dumb Ass.

So get the vaccine.  And pass this essay on to someone else.  The life you may save may be your own. Or be a Dumb Ass.

And if you and yours are admitted to the hospital or visit a HCW during the flu season, ask if your provider has had the vaccine. If not, ask for a new provider.  Who wants their health care provided by a Dumb Ass?