Emerging diseases and zoonoses #5–Chikungunya

So far this week, I’ve mostly been talking in generalities–the introductions to the topic, or how the animals we eat or other types of human behavior can put us at greater risk for the emergence of such diseases. Today I want to talk about a more specific example: an ongoing outbreak of a virus called chikungunya.

Chikungunya (from the Swahili word for “stooped walk,” or “that which bends up” depending on who you believe, referring to the posture of a person suffering from the disease) is an arbovirus: a virus that is transmitted by insects. In this case, the insect in question is the mosquito, including the nortorious disease vector Aedes aegypti, which can transmit dengue and yellow fever in addition to chikungunya and other diseases. The virus is considered to be “emerging” because, though it was identified in the 1950s, it appears that the virus is spreading into new geographic areas; so it’s not its novelty, but the extension of its range that is the issue.

Chikungunya isn’t a higly fatal virus, but it is frequently debilitating. After an incubation period of around a week, the patient suffers from sudden onset of a high fever, chills, and headache. Joint pain can be significant, and may persist for weeks. A rash may be present, and in rare cases (more common in children than adults), a hemorrhagic fever manifestation may occur. And while the virus is endemic in many areas of the world, it is not generally as much of a problem as the other Aedes-carried diseases.

However, when it causes an epidemic, it doesn’t mess around. This is what’s happened recently on the French island of La Reunion (located in the Indian Ocean near Madagascar). Though it’s been reported that the outbreak is in decline, the numbers over the past several months are pretty staggering. Of a population of around 770,000 on the island, somewhere between 110,000-218,000 people (depending on whose estimates are used) have contracted the virus in the last year, with up to 155 deaths. At the beginning of February, new cases were coming in at a rate of 47,000 a week–down to just over 4000 now. This marks the largest outbreak of Chikungunya since we’ve been studying the virus. Other countries in the region, including Seychelles and Mauritius, have also suffered outbreaks, and reports of a similar disease in several regions of India (a map of suspected cases can be found here) suggest that it’s likely chikungunya is doing damage there as well.

The reservoir of Chikungunya is unknown; indeed, it’s not known if there even is a non-human reservoir. It certainly seems to be maintained well enough within the human population: people become highly viremic (have lots of virus in their blood), the mosquito takes a blood meal, and passes along the virus in its next bite. This doesn’t rule out a reservoir species, but it does show that one isn’t necessary for outbreaks. This is why chikungunya has the potential to be such a problem: how many viremic people would it take to enter a country and allow the virus to become established in a new area? What if there are American tourists on La Reunion or other islands in the area who are infected–possibly even asymptomatically–and return to America with enough virus in their blood for a hungry mosquito to pass the infection along? Could we see a new West Nile in America, another arbovirus creeping across the United States?

As with many arborviruses, it’s largely the control of the vector species that results in control of the disease. Indeed, French president Chirac has sent in ~4000 people in an effort to eliminate mosquito breeding grounds on the island. A vaccine for the virus was also developed by American scientists in the 1980s, but due to the relative rareness of the disease, its low death rate, and its absence in many of the wealthier countries (and hence, difficulty getting a pharmeceutical company interested in further development), the research was largely dropped, although obviously these recent outbreaks have revived interest. In the meantime, the French government is taking a lot of heat for their handling of the outbreak, with some referring to it as “their Hurricane Katrina.” And while a mass vaccination campaign would have been unlikely even if the outbreak had been caught early on, the French government is now spending $110 million (US dollars) in health and economic aid–likely much more than would have been spent if they had hit early before the virus spread throughout the population. Let this be a lesson for the US or other countries, should Chikungunya or similar pathogens again reach our shores.

Images from http://www.kompas.com/photo/metro/Chikungunya.jpg and http://www.lexpressmada.com/img/illu/ill20061502_23.jpg

36 Replies to “Emerging diseases and zoonoses #5–Chikungunya”

  1. The reservoir of Chikungunya is unknown.
    I was wondering what exactly you meant by “the reservoir.”

    And by the way, I’m in Mauritius and I’ve seen people with the virus. It’s not half as horrible as the media’s preconceived image of the disease. However it must be stressed that some people do appear to be more affected than others.

    Chikungunya mainly affects the joints so it can be painful.

    P.S. I just killed an Aedes aegypti!!!
    P.P.S. My blog entry on Chikungunya.

  2. I was wondering what exactly you meant by “the reservoir.”

    The species that maintains the virus in nature. Does it circulate solely in human populations? Is there another animal where it’s maintained and introduced frequently into the human population?

  3. Okay, got it. There’s a question which I’ve been asking myself too: the epidemic seems to arise at about the same period of time each year (that is for 2 years) and it disappears at… guess what, the same period of time too. I was wondering why this is so.

  4. Depends on the area. Obviously here in Iowa, bugs are only a problem a few months of the year. In warmer areas where winter isn’t a problem, variations in seasonal rainfall can affect mosquito breeding grounds, so that they may only be able to be around for a few months due to water, not temperature. I don’t know enough about the climate and mosquito breeding on Reunion Island or the surrounding areas to say anything about the mosquito life cycle there.

  5. Recent epidemic of Chikungunya in certain districts of Andra Pradesh in India has indicated possibility of involvement of some domestic or sylvatic animals which could act as reservoirs for this disease. For example, primates may act as reservoir and they may maintain the chikungunya virus and a slient transmission may be going in forest ecosystem of a nearby village (?). When people go for firewood collection or agriculture, they may acquire the virus and become the source of infection for tramsmission among human beings. Another possibility is that the reservoir monkeys (?) transfer the virus to human beings when they visit the nearby village. Further, the acquirement of first infection is of great epidemilogical significance. Monkeys, dogs, cats, goats, cattle and rat populations should be screened for the presence of Chikungunya virus in their blood.But we were not able to do this owing to strict ethical issues. As far as my experience in the epidemic villages is concerned, the behaviour of water storage of the people may speed up the spread of the disease. This is mainly due to inadeqate water supply. I have seen a minimum two eartherm jars in each house, that even inside their dwelling. Newly emerging Aedes aegypti mosquitoes from these jars are able to find the host easily. If one is infected, the transfer of virus to other members of the family happens very quickly. If there is transovarial tramsmission among vector mosquitoes, the severity of epidemis would be very high.
    Health education and source reduction are the effective means of controlling the disease. Fogging and antilarval measures are useful only during epidemics.

    Research Assistant
    Division of vector biology and control
    Vector Control Research Centre (ICMR)
    Pondicherry- 605 006. INDIA

  6. Re: chikungunya and other mosquito-related diseases, I have a question and was wondering whether anybody has enough information and time to answer it. My 15-year-old son is going to Madagaskar with his school in July and I heard there have been cases reported there in February. Would regular malaria prophylaxis and supervised application of mosquito repellant be enough as far as general prevention is concerned? What medication should I include in his travel case? Thanks

  7. Hi

    I’m from Mauritius, where accordingly to official figures, there are only about 3000 infected cases. However, seeing the spread of the virus at hospital – non-official figures, people are beginning to wonder whether the virus is not spreading other than by mosquito bites.

    We are now at the start of the ‘winter’ season where we normally see fewer mosquitoes – but the cases of infection appear to be rising. Again, this is not the same as the ‘reported’ cases of infections as there are many that goes unreported and thus, unofficial.

    Is there any possibility for the virus to be able to infect via other means?

    Yours sincerely


  8. is chikungunya fatal?can it be the direct cause of deaths?if yes, what is the pathology behind?media has attributed a lot number of deaths to the illness in the state of andhra pradesh,(India) but the health authorities are declining to accept it . who is correct?

  9. Hi B and others,

    Unfortunately, I simply don’t have access to the data in individual states and other areas regarding the outbreak, so I certainly can’t answer “who’s correct” regarding figures. Generally it has a low fatality rate, but it can cause death. As far as the virus being transmitted via other means, I suppose it’s theoretically possible to be passed along via dirty needles, but I don’t know of any other natural transmission route that’s been confirmed.

  10. hi
    am from mauritius. here doctors are quite confused about the differing cases of chikungunya reported in patients. the number is rising day by day while the government claims that this is not the case. people are taking all sorts of medecine and cortisone remedy but this is not recommended by scientists while here doctors are using these daily..

    above all, it seems that just yesterday it was in the news that the chik virus has been transmitted to our indian ocean region by americans.. a viral sort of attack, is it revenge ! is it true and if this is the case what can we do now

  11. Hi I from Mauritius Island and I have some questions about several effects that mosquitoes fogging or spray, can cause on the natural fauna and flora of our Island? Does chemist solution would’n affect us?

    Thank you

  12. can anybody send me the treatment (medicine)prescribing part for my patients for chickungunya? please send it through Email to my Email address# (dr_shujakhan@rediffmail.com)

  13. can anybody send me the treatment (medicine)prescribing part for my patients for chickungunya? please send it through Email to my Email address# (dr_shujakhan@rediffmail.com)

  14. hai i am practising general medicine in Warangal district of Andhra Pradesh state of INDIA, well i am glad to inform that i am able to send my patients home with satisfaction after they are treated for chikungunya, my line of treatment included only few priliminaries; 1. First day of fever let not temperature rise upto 104 degrees, just use PCM i/m injuctions and oral ENZOVEXX TABS twice daily, it will have good prognosis on the further disease progression. well i am practising same for each and my results speak my victory. Hope u all try it out for better Planet health. Thank you.

  15. this is the best site till now. they are doing a great job.informing the people about htis deadly virus.keep it up. i would suggets oyher people to visit this site so that they could also learn about it.i am quite impressed.;

  16. hi im a student doing genetic eng….im intersted in knowing facts about suddenly arising strange diseases or disease causing pathogens and its effects. i want to know which blood group is most effected by ..cause i have heard that it particurly has an adverse effect on a particular blood group… YOURS SINCERELY FEBELA

  17. Dear Folks –
    …for the past two months I have been in Mauritius, gleefully, insanely, frantically killing dozens of ‘mozzies’ EVERY day in my [clean] apartment; yet the situation here, because of the intransigence & subtrefuge of the various Ministries to “action” the Community EDUCATION ‘Action-Plan’ given them [outlined for them MONTHS AGO from Singapore Public Health Officials & used most successfully there], is nearing FULL epi-demic levels. I have spoke at length to the CEO of the “Association des Hoteliers et Restauranteurs – Ile Maurice”, the Group who most stand to lose their shirts & other anatomical parts when the ‘fruits’ of all the ‘out-sourcing of Public Health are reaped when it warms-up in a few weeks[October 2006]. Everybody there agrees that the Singapore ‘action-plan’ [which I was shown] is comprehensive & effective way to ‘target’ school students [in English, French & Creole] for them to THEN educate their parents of the need for the local DAILY clean-ups. Yet nothing but nuthin’ has been done. “Perhaps in October…” I am told. The big-boys actually have ALREADY “put the blame” on the faceless, nebulous nameless public servants who are somehow ALREADY at fault for the ineptitude & inaction of their Bosses, who will just fly-out of the country with their families when the fecal-matter hits the fan next month. Right. [Fix the blame or Fix the problem?] “Public” health? Accountability? Transparency? Shure. See you at the airport. /// Yet, on a lighter note, I was [again] informed by a Staff person in the local Pharmacie [chemist] here that “the reason that ‘chik’ is here is because of ALL the “INFECTED TOURISTS.” Gee, now I understand everything. I will again go visit the big-boys at the “Ministry of Funny Walks” and assure them that soon, very soon, all their ‘problems’ of all these unwashed masses of “infected” tourists will just magically solve itself. Soon. Very soon. /// ps. – One of the Civilian Pilots here who got infected last month with ‘chik’, was advised [from Denmark] to use TUMERIC [cajun word here is ‘saffron’] every day [3.7g dried or 14 g fresh], pre-dawn [0300] to keep swelling of hands down to managable levels by sunrise. He has been doing this for two [2] months and, [as a Engineer], he ‘swears’ by its efficacy. Any feedback on this? His hands DO actually look much better, he has been able to continue to work. Same old story : “Treat the ‘effect’, not the ’cause’.”

  18. I’ve read that the curcumin in turmeric does have anti-inflammatory properties. I’m surprised turmeric goes by “saffron” as well, because those are two different things in my spice cabinet… turmeric is a yellow powder, and saffron is yellow fronds. I suppose he could be taking saffron, but saffron is far more expensive. (Which leads to some restaurants using turmeric to color foods instead of saffron, which may be the source of the confusion.)

  19. chikungunya is more pronounced by the mosquitoes that are breeding in the surging ground waters in deep mines that are left unguarded in Kolar Gold Field , Karnataka. In Tanzania too , these mosquitoes bred in gold mines

  20. I suffered from chicungunya for three days.I have taken homeopathy medicine and accupunture.I have seen people getting relived of the pain and cured without side effects.Many of friends who suffered and took allopathic medicines didnt find any cure for the pain.When they tried the alternate therapies they were relieved.

  21. im suffering from the aedes infected disease for a week now.all i can say is please for heaven’s sake get rid of the insects near you.believe me it’s hell not bein able to do anythin.even torturous to type this simple blog.beware people!

  22. I have some patients who have after Clinically diagnosed Chickengunya during the current epledemic in Western India, have symptoms of joint pains and findings resembling rhematoid arthritis

    These have persisted despite Paraacetamol and usual pain releviers

    Kindly let me know use of Chloroquine, or hydroxychloroquine sulphate could be useful

    and Also of Steroids in view of the persistant trouble and likely plermanent damange

  23. Chickengunya is now rampant in Sri Lanka….can it be caught from another person, or does it have to be from the mosquito……

  24. my relatives are in coimbatore(Tamilnadu,India) and recently(dec 20,2006) being affected by chickungunya . It looks like it still hasn’t been controlled in coimbatore. They are suffering very badly. its been 2 weeks,since they were admitted in hospital.more than a week in Intensive care unit.
    various symptoms are seen. including adhoc memory loss.
    hope its controlled soon, before it comes another round..

    Is the memory loss , a regular symptom? will it get cured after chickungunya is cured?

  25. I’ m from Sri Lanka, I’m suffering of chickungunya all my joints and old injuries of my palm knee and foot are very painful and unbearable. No normal life is possible it is past 6 weeks since I had fever. what is the best treatment.

  26. I have done a lot of research on Chikungunya. I am sorry to hear about all Chikungunya patients and their suffereing. Coz I am my self a vitim for the last 1 1/2 years. although they say Chik-V ( Chikungunya) is not fatal the virus leaves behind a trail of ilnesses caused by the virus which is mis-diagnosed by the doctors, and these lead to debilitating, someimes fatal circumstances. The virus apears to damage the protein cells of the body for a prolonged period while concentrating in the human joints. as a result the degeneration of joints start and if it does not get better the victim will suffer for a long time. The patients unusually also lose weight. The infected human body starts TRYING to throw the virus out ( by the immune system) and as a rsult extreamly ithchy rash comes on limbs, fingers, palms etc. In some, kidneys also get affected due to continuous efforts to filter what ever the left behind. In some people lungs get affected and they start accumilating water( Body liquids) inside the lungs, and this leads to heart failure. In other words the body tries to rid the virus which binds itself very strongly to the cells of the victim. WATCH-OUT for alergic reactions after getting infected. The only way I have found to minimise the damage is – Take high protein food(if your kidneys ok). Increase the intake of vitamins ( C, E, B) with minerals especially calcium with Vitamin+D3. This will regenerate the joints damaged.Take COLROQUINE under medical supervision for VERY SHORT periods. This will improve the condtion dramatically. Well it worked for me.Hope everybody will get well.

  27. how this chikungunya virus attack our body??why does our platelet count decreases when we have this virus in our body??

  28. Dear Dr,

    Kindly let me know any possibility of the patient to get re-infected after recover the this disease.

    Now,Malaysia is having this outbreak for more than 3 months and about 10,000 people were infected.

    Yours advice is highly appreciated.

    Regards and thanks


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