Chikungunya update

I feel a bit guilty. I still get occasional comments on this post about the outbreak of chikungunya on several islands in the Indian Ocean. Since I’m obviously not involved in the actual outbreak investigation, all I have to offer is news reported elsewhere–and it’s not exactly been a landslide of information. However, Nature does have some news to offer, based largely on a new paper published in PLoS Medicine (summary here).

Previously, the complete genomes of three isolates of the virus had been determined. Two were from strains isolated in 1952 during the first known Chikungunya outbreak, and the third is from an outbreak in 1983 in Senegal. In this new study, the authors determined most of the genetic sequence from 6 additional viruses taken from patients in different geographic locations, at different time points during the outbreak, and from patients with different clinical presentations. Additionally, they sequenced a portion of a gene encoding a membrane glycoprotein in 127 other viral isolates. They found that one strain (E1-226V, see below) emerged during the outbreak and increased in frequency over the past several months as the outbreak has become more severe. Interestingly, this particular mutation has previously been found to release the cholesterol dependence of the related Semliki Forest virus–in other words, it no longer needed cholesterol in order to fuse its virus membrane with the host cell membrane.

As noted in the Nature summary:

The outbreak seems to be more severe than the sporadic occurrences of chikungunya that have hit Africa and Asia in the past: it has spread like wildfire, infecting some people’s nervous systems and even killing a fraction of its victims.

The authors suggest that the E1-226V mutation may provide the virus with a selective advantage in its mosquito host, but this hasn’t been experimentally tested. This could be one reason the outbreak has been more severe: more infected mosquitoes, more chances to infect humans, greater numbers of deaths.

Second, they used the data from the sequenced isolates to put forth an evolutionary scenario of isolates. It’s a lot of information, documenting the nucleotide changes in the 6 sequenced isolates; note the increase in the E1-226V strain:

Finally, I want to return to the Nature summary and emphasize one quote:

Until now, chikungunya virus and its relatives were studied by only a handful of scientists. “There was the attitude that if it doesn’t kill people it’s not important,” says Scott Weaver, who studies this family of viruses, also at the University of Texas.

I’ve received some grief on here for spending so much time and energy discussing H5N1 or other microbes that currently aren’t a big cause of mortality in the human population, but this chikungunya outbreak shows how a fairly “insignificant” microbe can suddenly become a major player.

Reference

Schuffenecker et al. 2006. Genome Microevolution of Chikungunya Viruses Causing the Indian Ocean Outbreak. PLoS Medicine. 3(7): e263. Link.

Image from http://medicine.plosjournals.org/archive/1549-1676/3/7/figure/10.1371_journal.pmed.0030263.g003-M.jpg

Comments

  1. I am very surprised at the fact that you have “..received some grief on here for spending so much time and energy discussing H5N1…”.

    We consider your blog to be one of the most interesting and informative on the web. Over the last few weeks however, you have made no mention of this increasingly important virus in your blog.

    Please can you ignore the silly people who want you not to spend time on the Avian Flu situation?

    Please do start blogging again about this growing global threat, so that we can once again add your impressive blog, in to the Best Bird Flu Blogs section of our site?

    The Best Bird Flu Blogs team.

    http://www.birdflubreakingnews.com

  2. #2 Tara C. Smith
    May 25, 2006

    Thanks for the compliments. I have discussed it a bit, but mostly in passing for a variety of reasons. I have posts in the queue for a few days but will probably get back into flu next month.

  3. #3 Hank Barnes
    May 25, 2006

    Please do start blogging again about this growing global threat, so that we can once again add your impressive blog, in to the Best Bird Flu Blogs section of our site?

    Growing global threat?!!?

    Yeah right, birdbrains Here’s a nice graphic from your stupid little website.

    Note in the ENTIRE WORLD (population 6.5 billion) over the past 3.5 years, there has been a whopping total of 126 deaths from bird-brain flu.

    During the same period –in just the U.S. — you have about 350 deaths from lightning strikes.

    Growing global threat my arse:)

    HankB

  4. #4 Tara C. Smith
    May 25, 2006

    Hank, we all know you disagree. Can you at least *try* to be civil?

  5. #5 Hank Barnes
    May 25, 2006

    I am being civil:)

    These bird brains are totally clueless. How many people on the entire planet died of something since 2003?

    What? 2 million/year in the U.S. So, lemme crudely extrapolate (2 x 3.5 x 24) =

    Total deaths in the world since 2003: About 168 million.

    Thatsa lotta people. Hopefully, many simply succumbed to old age.

    And, of this 168 million deaths, 126 are supposedly attributable to some mysterious bird-brain flu???????

    My God — it’s the exact opposite of a growing global threat. It’s a stagnant trivial non-threat, a mere statistical blip on the human species.

    HB

  6. #6 Viji
    May 26, 2006

    Hank .. Hank .. despite thinking of yourself to be of a civilised lot, you’re very far from being civil. In fact you’re probably the only odd person disillutioned to think of yourself as civil .. having quoted your buttocks and equating human brains to that of our ornithine cousins inn your previous posts. Perhaps you have a warped moral standard

    That said … having seemingly, statistically minute no of cases does not mean its not an emerging threat .. perhaps you were the few naysayers who said HIV-AIDS, or MRSAs were not globally significant when these epidemics were in their infancy “mere blip on the human species”; THAT is so dull minded as you seem to be, or you are just plain arrogant, misinformed, and stubborn troublemaker. It is also fair to say that it is irresponsible for the scientific and epidemiology community not to look into it, especially with the wealth of data from past flu pandemics starting out as an “irrelevent” bird flu

    I believe that bird flu is a potential global health threat, and I applaud Tara for her fair and informative presentations of the bird flu

    BTW have anyone had a good look at the latest cluster of new human bird flu cases in Indonesia?

  7. #7 Viji
    May 26, 2006

    Who is this Hank Barnes by the way, I’ve think I’ve seen him raving before in quite a few blog visits; ravings with little constructive contributions, I should say.

    A colourful character he definitely is hahaha

  8. #8 Hank Barnes
    May 26, 2006

    Viji,

    I believe that bird flu is a potential global health threat,

    Who cares what you believe. This ain’t church.

    Hank B

  9. #9 DR.P.GNANAGURU, M.D.
    August 29, 2006

    good information are provided

  10. #10 n. dahora
    October 12, 2006

    Dear Dr.
    I am a Space Physics PhD student.
    Kindly tell me that will a patient infected by Chikungunya show a increased RA factor and ANA during the term of desease(1-15 days).
    If yes then how to differentiate between the symptoms of R. Arthritis (RA) and Chikungunya.

    Reply soon

  11. #11 jspreen
    October 12, 2006

    Hey Tara, am I not allowed to post anywhere on your blog anymore or am I just rejected from the marvelous “people out there” thread? Just checking things out…

  12. #12 jspreen
    October 12, 2006

    Hey, that’s crazy: Here everything is working fine. What’s up Tara? Can you please be honest so we can all learn the rules you impose without telling? Or is your boss imposing things ?

  13. #13 groucho
    October 12, 2006

    jspreen asked me to post this because again he’s having problems getting this wonderful messages published. This time it seems to be worse than before and the current message seems to be filtered on it’s contents too. This message was detined to the “People out there” thread but even I can’t post it there. This thread seems to work fine though. groucho
    ———————————–

    Some basic information for specialists directly from the world of other specialists (I will hope that they understand each other’s language) :

    http://patient.cancerconsultants.com/bone_cancer_treatment.aspx?id=33040 :
    What are the diseases that affect the bones?

    Among the most notable bone diseases are osteoporosis, rickets, and cancer. An imbalance between bone formation and bone resorption underlies nearly every disease that affects the adult skeleton. In osteoporosis, bone is broken down faster than it is rebuilt, resulting in lighter and more porous bones that may not be strong enough to support the body. Rickets is a children’s disease in which the bones are inadequately mineralized. As in osteoporosis, the bones are weakened and weight-bearing bones, particularly in the legs and pelvis may fracture or bend.

    Cancer can start in the bones or spread to the bones. Both types of bone cancer can compromise bone health by causing increased build-up or excessive breakdown of bone. Additionally, cancer treatment may damage or weaken bones. Most notably, cancer treatments such as hormonal therapies for breast and prostate cancers can cause increased bone loss.

    http://www.healthtalk.com/otherconditions/interviews/coleman/page02.cfm :
    Dr. Coleman:
    Not really. The damage from cancer is much more extreme, it’s much [more] localized than osteoporosis. The cancer will create holes within the bone and major areas of destruction, from [a] centimeter or more across, whereas osteoporosis is a diffuse process. It’s a thinning of all of the bone, and it’s not patchy like cancer is.

    So, if we may believe Dr Coleman, the difference between cancer and osteoporosis is merely a question of extremeness.

    http://patient.cancerconsultants.com/bone_cancer_treatment.aspx?id=33040 :
    Two types of cells are involved in the remodeling of bone: osteoclasts and osteoblasts. Osteoclasts are the cells that break down bone, converting the calcium salts to a soluble form that passes easily into the blood. Osteoblasts produce the organic fibers on which calcium salts are deposited. In healthy young adults, the activities of these two cell types are balanced so that total bone mass remains constant.

    So it seems that, even in dummy world, bone disease is a matter of unbalanced processes and there’s cancer on either side.

    Hamer’s New Medicine for intelligent grown-ups who do not fear being the laughing stock of the ignorant newspaper reading and television watching majority of the Planet Earth teaches us that wandering cells causing metastasis is a fairy tale. The NM also shows us that excessive breakdown of the bone is caused by a biological conflict of loss of self-esteem. Increased built-up occurs after the conflict has been solved, during the repair phase of the previous damage caused by the biological conflict.

    As far as I know, osteosarcoma is mostly the result of a damaged periosteum which enables, during a repair process, excessive bone growth all over the place, not unlike fresh concrete spilling through a damaged formwork. But that is my personal opinion which, if proven to be false, should not be used as a nail to Hamer’s coffin.

    js

  14. #14 Seth Manapio
    October 12, 2006

    Help, help, I’m being oppressed!

  15. #15 Shekhar
    October 22, 2006

    Could someone direct me to a site (information) that will help me understand:

    1. What is the current understanding at the molecular level of Chikungunya infection?

    2. Why do we develop pain in the bones (do we understand this once again at the molecular level?)

    3. Is any effort being ongoing to develop new drugs against Chikungunya?

    Thanks,

    Shekhar

  16. #16 Robster
    October 22, 2006

    I’m not familiar with this virus, but as to bone pain, inflamation of tissue surrounding nerves could be a cause of the pain. Just a thought.

  17. #17 jspreen
    October 22, 2006

    3. Is any effort being ongoing to develop new drugs against Chikungunya?

    There’s been a big thing going on in France and on the Reunion Islands about a magnesium chloride cure against chikungunya. MgCl2 is said to be be very effective. Check it out!

  18. #18 Robster
    October 22, 2006

    js, can you provide a link? I’m curious as to why MgCl2 would have any effect. Of course, som alties like to count it as one of the many cure alls that they sell. Otherwise, I’ll take it with a grain of NaCl.

  19. #19 Seth Manapio
    October 23, 2006

    “MgCl2 is said to be be very effective”

    —————

    Against what? A helpful virus that is only trying to heal the body of the cancer caused by a DHS? Or are we dropping Hamer, now that you’ve managed to falsify him?

  20. #20 Dr.Niranjannath
    October 24, 2006

    Gujarat is at present affacted with chikungunya.Modern medicine has not been much successful in controlling chikungunya, so government is trying Ayurved and homeopathy.We would like to know about the post illness changes in the body.Awaiting your reply.

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