Effect Measure

A reader (hat tip River) sent me a link to a New York Times piece quoting a physician who recently saw swine flu cases in Mexico City. He called attention to what seemed like an anomalous clinical presentation of many cases. Besides a higher proportion of gastrointestinal symptoms (nausea, vomiting, diarrhea), Virginia Commonwealth infectious disease specialist Dr. Richard P. Wenzel was surprised that many cases, even severely ill ones, did not have fever:

Many people suffering from swine influenza, even those who are severely ill, do not have fever, an odd feature of the new virus that could increase the difficulty of controlling the epidemic, said a leading American infectious-disease expert who examined cases in Mexico last week.

Fever is a hallmark of influenza, often rising abruptly to 104 degrees at the onset of illness. Because many infectious-disease experts consider fever the most important sign of the disease, the presence of fever is a critical part of screening patients.

But about a third of the patients at two hospitals in Mexico City where the American expert, Dr. Richard P. Wenzel, consulted for four days last week had no fever when screened, he said. (Lawrence Altman, New York Times)

High fever is indeed a characteristic finding of influenza illness, but many cases of seasonal flu are asymptomatic. After reading this I did a quick search of the literature to see what proportion it is. One of my virology textbooks says as many as half of flu infections are asymptomatic, while a recent systematic review of the literature of 56 different volunteer challenge studies estimates it to be about a third. In the same review, the frequency of fever in influenza A infections was about 40%, not too different from Dr. Wenzel’s clinical impression. Since subjects in volunteer challenge studies are mainly young, healthy adults, this comparison is probably appropriate. The authors of the review conclude:

Pessimistically, viral shedding peaked rapidly, infections were rarely “typical,” and symptoms or signs widely used for influenza case definitions (e.g., fever or cough) would be unreliable for identifying infectious individuals. (Carrat et al.,”Time Lines of Infection and Disease in Human Influenza: A Review of Volunteer Challenge Studies,” American Journal of Epidemiology 2008 167(7):775-785; doi:10.1093/aje/kwm375)

In other words, the absence of fever might not be particularly unusual. On the other hand, the relatively high prevalence of gastrointestinal symptoms is a worry:

Also, about 12 percent of patients at the two Mexican hospitals had severe diarrhea in addition to respiratory symptoms like coughing and breathing difficulty, said Dr. Wenzel, who is also a former president of the International Society for Infectious Diseases. He said many such patients had six bowel movements a day for three days.

Dr. Wenzel said he had urged his Mexican colleagues to test the stools for the presence of the swine virus, named A(H1N1). ?If the A(H1N1) virus goes from person to person and there is virus in the stool, infection control will be much more difficult,? particularly if it spreads in poor countries, he said. (NYT)

Gastrointestinal symptoms are also seen in H5N1 patients. The question whether there is intestinal infection and carriage is of importance. We know little about the distribution of appropriate viral receptors in tissues outside the respiratory tract, and some data suggests that flu virus can successfully make the passage through the acid environment of the upper g.i. tract. Is ingestion a possible route for influenza infection? Conventional wisdom says, “no.”

But influenza is the surprise that keeps surprising.

Comments

  1. #1 Erich Heidenreich
    May 14, 2009

    Absence of fever, if true, must have been limited to Mexico, because according to a May 7 report published in the NEJM, of 642 confirmed cases: “The most common signs of illness were fever (94% of patients), cough (92%), and sore throat (66%)…”

  2. #2 WV_EPI
    May 14, 2009

    One aspect of this that should be considered is the fact that Dr. Wenzel noted that approximately 1/3 of patients in Mexico that he saw in the hospital setting with swine influenza (laboratory confirmed or not?) to be afebrile…while the literature cited on the volunteer studies refers to infected persons that are not symptomatic at all, and certainly not hospitalized. If Dr. Wenzel’s observations are true, case detection of infectious cases as well as some severely ill cases might evade the screening case definition (the acute URI part)…

  3. #3 revere
    May 14, 2009

    WV_EPI: You make a good point. We don’t know what the denominator of Wenzel’s sample is (in selection terms, not numbers). That’s another reason I am not keen on clinical impressions like this. It could skew judgments and practice without a good foundation.

  4. #4 DemFromCT
    May 14, 2009

    Erich, that might be self-selecting because only fever patients in the US would be tested.

  5. #5 mexobserver
    May 14, 2009

    Yesterday it was reported here in Mexico that researchers had encountered an as-yet-unidentified strain of the new virus (present in patients not only in Mexico but also in Canada and the US). I don’t know how reliable this is, as I didn’t find mention of it in foreign sources (but didn’t have time to look hard).

  6. #6 D. C. Sessions
    May 14, 2009

    Erich, just before A(H1N1) made the headlines my son (at University) had a week-long bout of severe GI trouble of the which-end-gets-the-toilet-first variety, combined with similarly severe muscle aches etc — but no fever. School NP didn’t even screen him. A few days later his roommate had high fever and other flu-like symptoms and was isolated on policy.

    Meanwhile the cow-orkers have been reporting a lot of GI upsets making the rounds in their families. No telling whether this is flu or something else, could just be coincidence.

    The fact that we don’t have any kind of surveillance set up to even detect the difference, however, should be a worry to us all.

  7. #7 glock
    May 14, 2009

    Forgive my naivete but as a lay person that loves this site and uses it pretty exclusively to gain some understanding of infections in general, particularly influenza, am I to assume from reports like the one mentioned above, that they have screened for a spectrum of viral and bacterial infection or antibodies, and concluded that the swine flu virus was solely responsible, for the gastrointestinal symptoms ?

    Is it also possible that some sort of latent viral symbiotic protection from bacterial infection is disrupted by the swine flu infection that may cause the GI symptoms.

    Something like this letter in Nature :http://www.nature.com/nature/journal/v447/n7142/abs/nature05762.html

    I ask because having traveled extensively in Mexico and am always VERY careful, I have still suffered mild bouts of “the squirts” while my Mexican friends, ate and drank with abandon, with no ill effects. I have always wondered why that might be, since most GI “issues” for travelers there, are bacterial in nature.

  8. #8 Dominic Ebacher
    May 14, 2009

    Now that H5N1 has hit mainland China – the increased rate of asymptomatic cases is going to do a great disservice to us all I suppose, allowing greater possibility of admixture between other forms of flu in the rural farming populace: even if efforts to prevent spread from those exhibiting symptoms had complete penetrance.

    It isn’t the Swine Flu that I fear: its the Swine/Bird/Human Flu that will end up being the real killer someday. Knowing what we can in advance about the precursor virii is important, thank you for making this post.

  9. #9 revere
    May 14, 2009

    glock: It is very difficult to diagnose the many viruses that may cause URI and g.i. complaints. All we know now, as far as I understand it, is that there is a higher prevalence of g.i. complaints in people who are also confirmed to have swine flu infection. This is also true of the US cases, so I don’t think it is Mexico-specific. Of course, things change as we start to sort this all out.

    Dominick: You point to a major concern, but I would be afraid of any flu. It is unpredictable and can do all sorts of things.

  10. #11 phytosleuth
    May 14, 2009

    Co-infection with Clostridium difficile?

  11. #12 Erich Heidenreich, DDS
    May 14, 2009

    DemfromCT and D.C.Sessions,

    Good points. Thanks.

    Perhaps this is one reason it is still spreading so well, with atypical case presentations going undetected in the U.S.

  12. #13 Jeremy
    May 14, 2009

    Great analysis. One question, as I learn some more lingo here: why are “volunteer challenge studies” so named? Is “challenge” used more broadly for intentional infection?

  13. #14 revere
    May 14, 2009

    Jeremy: Yes, a challenge study is an intentional infection of a volunteer, with detailed evaluation and follow-up to see what happens.

  14. #15 GeorgeT
    May 14, 2009

    About the fever, there is a question I’ve always wondered about. If you have a fever of like 101-102F, is it really a good idea to take a fever reducer? The fever is your bodies’ defense so aren’t you helping the flu by doing so?

    Note: I realize that if you have a really high fever (say 103-104F), that you need the fever reducer so you don’t overheat.

  15. #16 eddie
    May 14, 2009

    I had flu 3 weeks ago, before the story broke but not before the new virus started spreading. I think it is low probability that that was the new virus but am worried that I may be more open to new infections.
    I had the usual 2 days of high fever, aces over my body and nose and throat stuff. Since then I have just about cleared the cough but other things are showing up.
    For instance, I have had localised swelling, pain in the tissues around nostrils and now have earache.
    I also had a GI issue a week ago but am over it.
    One thing I notice. The infection I had showed much clear mucus and the cough was frothy. There has not been the tons of green goo that usually shows up.

  16. #17 Valerie Brown
    May 14, 2009

    So are these statements correct:

    1. Asymptomatic people are still infectious – if so, is it for the usual time?
    2. Asymptomatic people are not counted because they never go to a doctor
    3. Many swine flu victims are very ill with the other symptoms, just not the fever – so they may not be tested for swine flu if the doctor doesn’t realize this
    4. Asymptomatic people can still be hosts for the gene-trading that might bring us highly virulent swine flu or swine-bird-human flu

    Therefore, if all of the above, the number of cases is probably vastly higher than any PH agencies have calculated, and the odds of recombination are also much higher?

  17. #18 phytosleuth
    May 14, 2009

    I’ve noticed that many of the state health department websites do not mention number of hospitalized (some already released). A couple that do are Wisconsin and Massachusetts. These both mention the median age range as well.

    I was wondering if it’s too early to predict how many hospitalizations would start to overwhelm the hospitals? For example, if we have an idea of the percentage that are being hospitalized and we know the confirmed cases, we’d be able to sort of predict when the town or city needs to go to the next plan (whatever that is) because the hospital would then be overwhelmed. This prediction might offer some pre-warning, that is, so that plan B’s could start to be instigated.

  18. #19 ssal
    May 14, 2009

    How effective is the antidiarrheal loperamide in treating the diarrhea associated with the new H1N1? Also, the diarrhea that can be associated with H5N1?

  19. #20 revere
    May 14, 2009

    Valerie: i. We don’t know how infectious asymptomatic infected persons are since they shed much less virus. It remains in open question. Some scientists think they are not infectious.

    ii. Asx cases may or may not be counted. It depends on how case finding is done. In this outbreak, they may be counted in specialized studies of contacts but aren’t part of the “case count” (because they aren’t cases of illness).

    iii. We don’t know . . . yet.

    iv. We don’t know. Less likely, but possible

    phyto, ssal: These are good questions that we as yet don’t have the answer to. It is likely loperamide works but I doubt it’s been studied properly. As for hospitalization rate, I think we should get some fix on this in a few weeks.

    Patience.

  20. #21 Lisa the GP
    May 14, 2009

    And lest we forget there’s still this little thing doing the same-old-same old in the background. (exerpt from ProMed today):

    “A 4 year old Egyptian boy has contracted the highly pathogenic H5N1 bird
    flu virus, bringing to 70 the number of human avian flu cases in the most
    populous Arab country, the state news agency MENA reported.

    Egypt has been hit harder by the virus than any other country outside Asia
    and has seen a surge of cases in recent weeks. Ten new human infections
    have been reported since 1 Apr 2009, more than the country saw in all of
    2008. The latest sufferer from the virus is from the Nile Delta province of
    Sharkiya, MENA said.

  21. #22 BostonERDoc
    May 14, 2009

    Perspective from the ER:
    I have been involved with the care of several individuals with confirmed Influenza A/H1N1 2009 N. America (SO-IV) What has amazed me is that 1 of the cases had no fever and no symptoms–yet had an initial rapid Flu swab that was positive and sub-typed several days later to confirm SO-IV. Of note this person had done some air travel–so much for screening–lets stop that draconian nonsense and spend the money on more useful things like vector surveillance. The other 2 had fever–but only very mild –and barely reaching the case definition temp. In addition, one of the low grade fever cases had a negative initial rapid flu swabs but positive PCR that came back the next day and then confirmed SO-IV of the swab. . This translates into a PITA from an Emergency Medicine triage perspective since we typically think of influenza as the sudden onset of a train hitting you with fever and rigors. This puppy likes to elude. Confucius say :no or low fever with poor reliable rapid flu makes major headache for world.

  22. #23 The Doctor
    May 14, 2009

    The no fever thing really got my attention. Why? because it has been a dictum of medical practice that Influenza Infection = Fever + Cough at a minimum.

    So, the report from Mexico and the ER doc above is a real game changer for me.

    I was on call last weekend and spoke to a patient with a flu-like illness but because she did not have a fever I reassured her that she didn’t have flu! In retrospect, maybe I was wrong.

    Studies from the 1957 pandemic revealed that about 30% of the population showed serum evidence of infection with the pandemic strain yet had no history of an ILI. Revere says that asymptomatic patients infected with flu shed very few virons. What is the basis for this claim? I would appreciate a reference. I ask Revere this question because of my growing concern that these asymptomatic cases may well be a more important source of spread within the community than we have thought to date.

    I remain thunderstruck by the finding that patients ill enough to require hospitalization with Mexican Flu were not febrile. Where was the interferon? It just does not make sense. Cells damaged or killed by flu should result in the production of interferon which is one of the most potent causes of fever.

    For me, this is an anomaly and I would be grateful to anyone who can enlighten me about this.

    Grattan Woodson, MD

  23. #24 Robert Potter
    May 15, 2009

    I would expect that the CFR would tend to approach the hospitalization rate (TBD) once the percent of the infected population needing ventilation and/or IV re-hydration grows large enough to overwhelm the available supply of such medical services.

    Since the infectious agent is influenza, over time nearly everyone will have some exposure over multiple seasons to the new flu strain (or be vaccinated once available) and thereby develop immunity sufficient to provide community immunity to few that have not.

    Thus, the primary objective of public health for influenza is not to prevent any new infections. Rather it is to minimize the rate of spread so that the critical care services remain sufficient to address the small but growing percentage of severe cases with life-threatening symptoms.

    Let’s hope that less than 1-2% of infections require hospitalization, which is closer to the typical flu strain and outbreak. Most severe cases recover with modern medicine such as the ICU. In comparison the worst known pandemic flu of years 1918-19 led to temporary emergency hospitals in gymnasiums and shelters but without modern treatments and therapies. That epidemic prevalent among young, healthy individuals frequently led to pneumonia from staff colonizing from the nose/throat. However, that era did not have antibiotics nor ventilators.

    According to 2006 Critical Care publication, there are approx. 66,000 adult ICU beds currently providing critical care to 55,000 patients daily across the U.S. Additionally, for remaining hospital beds there is a limited # of mobile equipment including monitors and most importantly ventilators.

    As a nation we need to take steps to keep the new flu strain’s infection rates low enough that number of concurrent cases wrequiring ventilators does not exceed the space ICU bed capacity – approx. 11,000 – at any point in time.

    Since one contagious person may infect many others in close contact, the best strategy to minimize opportunities for new infections is reducing large gatherings and groups. Furthermore, since flu severity is ameliorated by exposure level, reducing time in confined, congested spaces is beneficial as well.

    Of course, the parallel course is working on rapid development and testing of appropriate vaccine and leveraging newest technologies and methodologies that evolved since SARS.

  24. #25 pft
    May 15, 2009

    Flu is no fun, but it’s a natural illness that we can not prevent given the lack of understanding of influenza. I do not agree with the preaching of fear. A healthy respect yes, but seems to me people are too fearful of things we can not control and which does not do much more than make most who get it uncomfortable for a while.

    If you have an underlying illness or are elderly fear may be justified, and certainly I understand the concern adults have for their kids, but being exposed to viruses for which there is no vaccine is a way to build up immunity. The native Americans were devastated by European viruses which they had no immunity to due to their isolation. The globalization of the planet helps to provide global community immunity, which may be why we have not had a serious pandemic since 1968, and nothing approaching the 1918 influenza which occurred during a World War.

    Robert Potter | May 15, 2009 1:09 AM

    “Thus, the primary objective of public health for influenza is not to prevent any new infections. Rather it is to minimize the rate of spread so that the critical care services remain sufficient to address the small but growing percentage of severe cases with life-threatening symptoms.

    According to 2006 Critical Care publication, there are approx. 66,000 adult ICU beds currently providing critical care to 55,000 patients daily across the U.S. Additionally, for remaining hospital beds there is a limited # of mobile equipment including monitors and most importantly ventilators.

    As a nation we need to take steps to keep the new flu strain’s infection rates low enough that number of concurrent cases wrequiring ventilators does not exceed the space ICU bed capacity – approx. 11,000 – at any point in time.”

    I agree with this. But steps to limit infection rates should be taken only when there is evidence that it is leading to a reduction in ICU capacity. This would be a far better indicator of when to take action than the number of confirmed cases. Developing community immunity is beneficial should the virus increase in virulence. Steps to reduce infection in the absence of evidence that ICU beds are filling up is not wise. Hopefully someone out there actually tracks ICU occupancy trends.

  25. #26 revere
    May 15, 2009

    pft: Well, cancer is a “natural” illness, too, but it is feared. Whethr it is natural or not, flu is, as you say, something to be respected. One person’s respect is another person’s fear. Use of the word “fear” is loaded. If we change it to “concern” or “respect” doesn’t change much if either way people remain clear-eyed.

    With respect to ICUs, we can’t follow that in real time. By the time they exceed capacity (and we are almost at or above capacity most of the time) it is too late. That is why strengthening the infrastructure — which includes having enough acute care beds, not only for flu but for heart attacks, strokes and all the rest — is critical here. If there are enough trained public health workers, the ones in maternal and child health, substance abuse, etc., can be moved to flu duties in an emergency. They are in place, know the rules and procedures and are public health professionals. But if they aren’t there, then that avenue of creating an instant reserve is gone. If we hadn’t stopped collecting data on hospital beds because of budget cuts, we might know where we were now. But we don’t. The same for social service infrastructure.

    Assume the ICU beds are already full and any additional will cause a shortage.

  26. #27 Peter
    May 15, 2009

    I know a confirmed case, she said it was the worst flu she had ever had in terms of pain and the principal symptoms were ‘coughing up wet cement’.

  27. #28 Jean
    May 16, 2009

    This link is to an article about a teenage girl in Manitoba who is very sick with complications from what is referred to only as influenza A.

    http://www.winnipegfreepress.com/life/funds-sought-for-ill-teenager-44969927.html?viewAllComments=y

  28. #29 Diogenes
    May 16, 2009

    Looking at the progress of this H1N1 flu outbreak, there are a lot of people being admitted to hospitals who had been taking Tamiflu. There is in vitro evidence that Tamiflu works but I in vitro tests are notoriously unreliable with viral illnesses. Is there any in vivo evidence that Tamiflu is working because I haven’t seen a single piece of good evidence that it is.

  29. #30 revere
    May 16, 2009

    Jean: We will see more of this (and there is likely more of it than we are seeing), because so far this is acting like a typical seasonal flu and flu is not a nice illness, something obscured when it is called “a mild flu.” Even a mild flu year makes many people very sick and kills some of them.

    Diogenes: There is evidence of two kinds about the NI drugs. First, they are looking for the most prevalent marker of a resistant mutation, the H274Y SNP; second they are doing further testing, I think it is neuriminidase inhibition assays. Second, we know from clinical trials that NI drugs work in influenza infections. They are not miracle drugs but they do blunt the force of an infection if given reasonably promptly (how promptly is a matter of debate) and that there is a correlation between the markers and the ability of the drug to work. Short of doing a clinical trial in the midst of an outbreak, which is probably not feasible ethically or legally, we go with what evidence we have, which is not nothing, but not as much as we would like in the ideal case.

  30. #31 christine park
    May 16, 2009

    Hi. I’m a 67-yr-old grandmama in tennessee. About a month ago my 19-yr-old grandson had a bad lung/sinus congestion, was pale and clammy and exhausted (but not hot), and said his bones hurt. No offense, but we don’t have drs here. He took extreme doses of vit C and was better in a day and well in four days. The next week I got tireder and tireder until I had to go to sleep every two hours . Nothing hurt, no fever.Then I started getting very congested in lungs and head. At least I coiuld move it but it didn’t help much because there was always more. A few times I woke up in the process of sittying up and saying “I’m drowning!” Soon I also had diarrhea.After a few days of this I took some of gs”s magic vit C and it certainly does drain stuff ver well!But it was my gransdon’s, and expensive, so I limited myself to 2 doses daily for 2 days. By then the stomach thing was about gone and at least I was not drowning, so Ijust stopped that, being afaid of XXvits anyway, and kept on living. It took me about two weeks to be able to live without naps. I write this to tell you 1.I had no fever and 2.my mucus was also clear or cloudy, not the nasty brightcolored junk. I told everyone “can’t have been the flu on the tv because i had the runs and had no fever” It certainly wasn’t very catching; onlky the two of us got it even though my gransdon is in the middle of a clump of teenagers who never get more than 4″away from each other, and I, even sick, am the one who not only ewasahes the dishes but (even worse)puts then away with my dirty old hands.Bless you all for caring what happens to the public health. Don’t be mad at me for not going to drs. If you saw these drs in action you wouldn’t go near themm either…in fact, Y’all beiung so dedicated and all, you might have to kill them so its better you just don’t think about it. Bless you all.

  31. #32 Leah Daziens
    May 16, 2009

    After reading this thread on flutrackers.com, http://www.flutrackers.com/forum/showthread.php?t=104203

    I would greatly appreciate thoughts / comments regarding pre-existing conditions as they relate to H1N1 hospitalizations / fatalities. I feel that every hospitalization mentioned on the news is minimized w/ “the patient suffered from a pre-existing condition”. The assistant principal in New York was said to suffer from a pre-existing condition, but his son later said that the only known health issue was that he had been diagnosed w/ gout 1 1/2 years ago. And, what, if anything, do we know about the pre-existing conditions for the Mexican hospitalizations / fatalities? Is there an assumption that since this flu is “mild”, if a person gets seriously ill, then that person obviously has some sort of pre-existing condition?

    Lastly, any thoughts on “New Experimental Treatment Being Used to Help Critical Swine Flu Patient
    The device, about the size of a printer, is called a Hemo-Modulator, currently an experimental treatment for those suffering from HIV and Hepatitis C.”, http://www.wpix.com/news/local/wpix-experimental-treatment-swine-patients,0,3295824.story

  32. #33 Diogenes
    May 17, 2009

    revere. There would be many ways to look at how clinically effective Tamiflu has been for H1N1. Just compare the outcomes for people who were given it early vs late vs not at all. That wouldn’t be too hard and I’m sure the CDC is doing it or has already done it. They don’t seem too keen on releasing any objective clinical data about Tamiflu. I cannot find any clinical data to show that Tamiflu has altered the course of the H1N1 disease.

  33. #34 Marissa
    May 17, 2009

    Diogenes: about a year and a half ago we conducted a study regarding the effectiveness of oseltamivir in H5N1 cases and looked at mortality rates. Reviewers at Emerg Infect Dis thought the data were interesting but ultimately the paper wasn’t published because we didn’t have enough data from Indo. Fair enough. The main result was “Oseltamivir-treated patients appear to have a small increase in survival rate in comparison to patients not treated with the antiviral (43% vs. 33%), but this should not be regarded as an optimal result, since the vast majority of patients were given oseltamivir several days beyond the recommended guidelines.” Only 6% of patients received the drug within 2 days.

    My point is that in real life I’ll bet patients with the H1N1 swine flu strain aren’t getting it in a timely fashion either.

  34. #35 Valerie Brown
    May 18, 2009

    A couple of questions/comments:

    1. re color of mucus: I thought yucky yellow-green mucus was a sign of bacterial infection, and clear mucus would imply viral, so if that’s correct, mucus color would not be a reliable flu diagnostic.

    and

    2. NYT piece 5/18 about spike in Japanese cases, http://www.nytimes.com/2009/05/18/world/asia/18flu.html

    Japanese authorities taking all flight passengers’ temperatures as they disembark. But if many cases of H1N1 don’t produce a fever, it’s no wonder the Japanese cases are spiking, yes?

  35. #36 l
    May 19, 2009

    My mother has been very sick for a month with what her doctor has called “kennel cough” and yes, I know that is a dog’s illness, but he didn’t have anything better to diagnose. Low fever, wheezing, excessive coughing, anorexia. He gave her a 5 day z-pak and since then she has developed c-diff. She’s now a very ill 67 yr old woman. She’s so weak she can hardly attend her first grandchilds’ graduation. She’s had red bleeding from the bowel (which her Dr attributed to hemerhoids?) She insisted on a c.diff test (because her father died of it) it was + , so….

    She’s better after the metronidazole for 5 days.
    As far as I know she was never given a flu test, and as I understand it, the rapid flu test, even if it is negative can be positive for swine flu. But the CDC is backed up.

    If this is all true= I’m thankful that she’s had it and spread some of the germs around.

    Next flu season (next Fall- september ) This is goin to hit like a tonofbricks.

  36. #37 JJackson
    May 20, 2009

    The Doctor:

    I am told the NS1 is not like seasonal, 1918 or H5N1 but as this is thought to be primarily involved in Interferon suppression it may be efficiently reducing production. Just a thought I have no evidence to show that is what is going on.

  37. #38 Kristin
    May 20, 2009

    Is it possible (and does anyone know if there has been testing for) MRSA CAP in the Mexico influenza population? From the studies I’ve been reading, severe complications and death are more typical in a younger population when the two are combined – and I’m wondering if anyone knows if this has been tested and/or ruled out regarding the excess mortality seen with the Mexico cases?

  38. #39 revere
    May 20, 2009

    Kristin: Have yet to see any detailed case series from Mexico, especially with regards autopsy and immediate cause of death data. The connection between MRSA and pediatric flu mortality has been noticed before, as you indicate. Here’s a post we did on it a couple of years ago:
    http://scienceblogs.com/effectmeasure/2007/06/when_children_die_from_flu.php

  39. #40 Bob
    May 21, 2009

    My daughter (18) had very close contact with a confirmed H1N1 case daily. She, and many others, developed these symptoms: low fever (less than 101F), aches, chills, sore throat – these symptoms lasted only about 24 hours. The most severe symptom for all of them was diarrhea which lasted about 2-4 days and for some, seemed to clear up only to come back again for another day or two. For many, the diarrhea preceded the ache and chill period. All-in-all it was mild infection. Many of these kids only missed a day or two of school as the confirmed case became known after most of the kids had recovered.

  40. #41 wendy
    May 22, 2009

    My daughter and I have been ill for two weeks.
    Started with 4 days of stomach sickness. Went away for about one day, then headache, fever, cough, again stomach vomiting.
    No diarrhea . We will start to feel better only a few hours later have fever and headache come back. It has been two weeks, and we can not even get tested. We are not getting better. I feel like this thing mutates and reinfects inside you. I around Tuscon near the border.

  41. #42 Anonymous
    July 18, 2009

    This is a great blog and you report the information in a sensible way. I would like to give you an anecdote of what happened in NW England UK just after Christmas. There was an alert about winter vomiting virus and indeed this happened to us as a family (not pleasant). However it was accompanied by a persistant cough with clear or little mucous, which in some cases lead to vomiting, escpecially in the children. We all had temperatures a little raised but nothing too serious and certainly not above 100. In my son’s class at school half the children had the same symptoms. My eldest children also had many friends with these symptoms in their secondary girls school. In nearly all these cases the symptoms returned. We are all cough free now but this took a while to clear up. I hope this doesn’t get to the dizzy numbers of possible deaths as predicted, 65,000 in UK. I certainly will be drumming into the kids the necessity of washing hands and covering mouths when sneezing/coughing.

    Thank you for continuing to provide us with useful information.

  42. #43 Kel
    July 21, 2009

    Hey,
    I’m from Labrador, Canada. Last monday I started getting symptoms of a cold, a very sore throat, coughing, a slight fever (37.8), the chills and weakness. I went to the hospital because I have a brother with later stages of MD and was worried about him catching it. The Doc took my vitals- a very high blood pressure 158/98 the first time to emerg and 165/98 the second time (a few days later), a 37.5 temp, 103 bbms, and a 99% oxygen. The doc also took a swab from my the back of my throat and up my nose (the nose being kind of sore) and asked if I was coughing mucus, I said yes and she took a sample. A few days later she got back to me to tell me that I had a influenze type a virus and that it could be the H1N1 and that if my brother started showing any symptoms to get to the hospital within 48 hrs of the first symptom. I still havent heard back on if it was the swine influenza or not but I believe it is. The days before I got flu symptoms I had a bad stomach and a few days into it aswell and I’ve had this now for over a week and I still have a pretty bad cough, I’m out of the house, living at the neighbours (they’re out of town) so no-one else in my family gets it. But I’m worried I might have some kind of chest infection, what signs would there be if I indeed did?

  43. #44 revere
    July 21, 2009

    Kel: you almost certainly have swine flu as almost all flu A around in North America now is swine flu. The question of when you should go to the hospital if you get a secondary infection we dealt with a bit here, but in general let your body be the guide and go if you start to feel bad or have trouble breathing. As for your brother, the 48 hour guide is probably so they can start him on Tamiflu in a timely way and it is good advice. If he has been exposed then the sooner the better. Sudden onset of fever, sore throat/cough are the most usual, although there is a higher than usual prevalence of nausea and vomiting at onset with this so that should be another tip-off. Get well soon.

  44. #45 Kevin
    July 21, 2009

    My wife and myself, here in Dublin (Ireland), are trying to determine whether we are experiencing these very low level mild symptoms or not. Since Sunday evening she was feeling a little achy and decided to lay low on Monday. No temperature above 37 and a slight sore throat.

    By Monday evening I was feeling a achy as well and had a sore throat and stuffy sinuses. By following morning throat was more notieable and so were aches at joints. By now (evening) joints sorer and eyes tired but temperature is 36.7.

    Are we overreacting ? It’s over a week since we returned from Milan (Italy) and as far as we know we have not been in contact with anybody with flu. Our health service here is rigidly sticking with necessary presence of fever and cough. We also have been told that it could be nearly an year before a vaccine will be available, unlike the UK who put in their order in time.

    Play safe and lie low for one more day or continue as usual tomorrow ?

  45. #46 revere
    July 21, 2009

    kevin: If you are able, I’d play it safe. A signficant proportion of swine flu nfections have no or low fever (see our post here. The health authorities are using fever as a bright line to prevent people who can care for themselves from burdening health facilities, but it’s not a reliable criterion.

  46. #47 Kevin
    July 22, 2009

    Contacted our doctor this morning. She said very few cases has tested positive for swine flu (they have stopped taking swab tests here). The doctor suggested taking another 24 hours to be on the safe side and if we got any worse Tamiflu can be prescribed. She went on to say that there are other flu like viruses going around at the moment.

    So lie low until to tomorrow. From the telephone conversation with the doctor, lots of people must be panicking. Playing safe is the name of the game really, especially if you have asthma or any other such condition.

    The mild symptoms are still much unchanged since yesterday. Joints are still achy, a occasional headache and sore throat has changed from a definite line of sensation below adam’s apple to a more overall soreness.

    Great to find a rational website such as this with no hysteria or overreaction but calm discussion.

  47. #48 Andrew
    July 27, 2009

    I am a 60 year old veterinarian in UK with a normal and active lifestyle but recently hit with flu like symptoms – lassitude, muscular aches, headache, enteritis and nausea, but no fever, very few sneezes and no respiratory signs. After 4 days the tiredness remains (unlike a cold or other viral infection) The UK government helpline for swine flu is dismissive if there is no raised temperature. The questions are (a) is it likely to be swine flu? (b) if so, is the lack of sneezing and coughing a good portent for others in the household wary of catching the infection?

  48. #49 revere
    July 27, 2009

    Andrew: Folks our age are being spared, relative to usual, and this may result in lesser symptoms even if infected. The fever criterion is more to triage out demand. It’s know that a significant fraction of cases don’t have fever. The help line are people reading from a script. So . . . (a) it certainly could be swine flu, but without a specimen and PCR there is no way to know; and (b) yes, it means you are less likely to spread the virus.

  49. #50 Glen
    July 31, 2009

    A feverless flu could be unusual that it causes people to be sterile, or at least it is what I have read on a site.

  50. #51 revere
    July 31, 2009

    Glen: Feverless flus are not at all unusual. As for the sterility part, you didn’t read it here. I have no idea what that’s about and have never heard of such a thing.

  51. #52 Lee-Ann
    August 5, 2009

    I have a tight chest and finding it xtreemly difficult to breath properly with severe headaches. This has never happen to me before.Could this be H1N1 symtoms

    Please advice
    Concerned Lee-Ann

  52. #53 Lee-Ann
    August 5, 2009

    I forgot to say that I have a bad cough aswell

    Lee-Ann

  53. #54 revere
    August 5, 2009

    Lee=Ann: Consult your doctor or health care provider or go to an Emergency Room if you can’t breathe. This is not the way to get urgent medical advice.

  54. #55 Anni
    August 9, 2009

    hello, from last 10 days my brother is suffering from cough n cold.. n he also have headache .. we consult our local physician n she said he il be fine after 3 days dose.. he give us some syrup also.. but he is still have cough n cold.. but he is not having fever.. n in our city ( New Delhi – India) about 200 cases r ter of swine flue. is that possible that without fever someone got swine flue.. is ter any other symptoms.. he is having his normal diet. please advice as soon as possible.

  55. #56 revere
    August 9, 2009

    Anni: Yes, flu without fever is possible (the US CDC says somewhere between 10% and 40% hav eno fever). But there are many other viruses that can cause his symptoms. If he starts to have trouble breathing or becomes feverish, take him back to the doctor or the hospital.

  56. #57 Anni
    August 9, 2009

    thank u so much… he is ok in breathing, no fever at all.. n not 2 heavy cough but i am very scared. his eyes is red n he also have body pain. i hope u understand my english. here only government hospitals r allow to do swine flue tests .. is ter any other test from which i got n idea what happen to him.
    Please advice .

  57. #58 r c gp
    August 13, 2009

    i work as a gp . i have been in contact with swine flu , confirmed by swab . i used a mask when this index patient came in as i had a strong suspicion he had this flu. He presented with severe cramps and diarrhoea , with chills and aches and followed by sore throat and chest symptoms . he is a 40 yr old smoker . his wife presented 5 days later with gastro symptoms , and chills , which settled to be followed by severe headache . she had her ususal smokers cough , not no more than that .
    i did the swab to cofirm the presence of the virus in the area .

    one week later i woke one mornng with severe lower stomach cramps and loss of appetite . within 24 hours i was fatigued , crampy , achey with diarrhoea , but no fever and no upper resp symtoms .

    I await swab results . it is clear to me that i regularly get flu ey symptoms for periods of up to a week without any fever and i presume this is due to milder body reactions mounted with age ( I am 55 ) and the constant exposure to viruses that goes with my job .
    I am more concerned at present with not infecting a close relative on high dose steroids for sarcoidosis , given that this new flu is still a bit on an unknown entity of a visitor and probably still evolving .

    this is the first time in 20 years i have taken time off work with a flu virus .
    i am wondering , if swab comes back negative, should i do antibodies .
    If swab comes back negative , i am also going to be wondering about the number of false negtive swabs /

    congrats on this blog , it is easeily the most informative, detached and non hysterical i have come across to date . Kind regards .. rc

    ps , i do not believe i contracted my current viral illness from the swab pos patient . I believe i contracted from some other virally infected patient or person in the area.

  58. #59 r c gp
    August 13, 2009

    i work as a gp . i have been in contact with swine flu , confirmed by swab . i used a mask when this index patient came in as i had a strong suspicion he had this flu. He presented with severe cramps and diarrhoea , with chills and aches and followed by sore throat and chest symptoms . he is a 40 yr old smoker . his wife presented 5 days later with gastro symptoms , and chills , which settled to be followed by severe headache . she had her ususal smokers cough , not no more than that .
    i did the swab to cofirm the presence of the virus in the area .

    one week later i woke one mornng with severe lower stomach cramps and loss of appetite . within 24 hours i was fatigued , crampy , achey with diarrhoea , but no fever and no upper resp symtoms .

    I await swab results . it is clear to me that i regularly get flu ey symptoms for periods of up to a week without any fever and i presume this is due to milder body reactions mounted with age ( I am 55 ) and the constant exposure to viruses that goes with my job .
    I am more concerned at present with not infecting a close relative on high dose steroids for sarcoidosis , given that this new flu is still a bit on an unknown entity of a visitor and probably still evolving .

    this is the first time in 20 years i have taken time off work with a flu virus .
    i am wondering , if swab comes back negative, should i do antibodies .
    If swab comes back negative , i am also going to be wondering about the number of false negtive swabs /

    congrats on this blog , it is easeily the most informative, detached and non hysterical i have come across to date . Kind regards .. rc

    ps , i do not believe i contracted my current viral illness from the swab pos patient . I believe i contracted from some other virally infected patient or person in the area.

  59. #60 lisa Greeson
    August 27, 2009

    Please advise or help…my youngest daughter is having odd symptoms. no fever, sore throat , fatigued greatly, pale flushed coloring-almost gray looking, headache and just has been lifeless for days. She began this illness with an eye issue, that doc let go for a couple weeks to 3. he said it was allergy, but I disputed that. Not normal eye…so finally this week he treated her eyes as if they r infected and gave us antibiotic eye drops. I too have similar symptoms and my doc gave me the drops too. They did a rapid swab for flu, strep, mono and even worked up her bloodwork. all either neg or normal. HELP…..really frustrated that she has some mystery illness and cuirous if anyone could maybe redirect our path to heal her….much thanks and God Bless, Lisa

  60. #61 revere
    August 27, 2009

    Lisa: I understand (quite well, unfortunately) your anxiety and frustration. Unfortunately there is no way to make a diagnosis this way. It sounds like you have lost confidence in your health care provider and if possible you need to find another one, but in any event, you should keep pushing until you get an answer you can accept. But keep in mind that there are many maladies we just can’t diagnose or understand and if may come down to your doc saying he/she doesn’t know what the problem is. That is very, very common and very disheartening. Since this sounds like it might be infectious, it would be good to see an infectious diesease person and have a full history/work-up if you can afford it. And sometimes the actual condition takes some time to “show itself” to the tests we have available, so if symptoms continue for a time, go back and try again. Not a very helpful answer but as honest as I can be. It would be malpractice to try to diagnose something over the internet like this.