Thursday, September 16, 2010

This isnt funny

We're in the middle of a deadly dengue season and I've come across several reports pointing to a local herb called tawa-tawa (Euphorbia hirta) as a 'cure' for dengue hemorrhagic fever (DHF). Apparently, it's supposed to raise the platelet count in patients afflicted with DHF. This report by Reggie Aspiras for instance quotes former DOH secretary Jaime Galvez Tan saying, “The first evidence that it increases the platelet count came from doctors in Cebu.” (I must note here that the article linked is not a scientific article. It was written by a chef writing a food column. No citation was given for this alleged claim by Dr. Tan.)

Another article, this time by renowned poet Krip Yuson recounts his experience with tawa-tawa. His son was stricken with dengue and he attributes his recovery to several herbal remedies, including tawa-tawa. "There should be no harm in trying tawa-tawa capsules," he writes. This popular blog (Jessica Zafra's) also extols the virtues of tawa-tawa, claiming that it is a hemostatic. Again it must be noted that neither Mr. Yuson's article, nor the blog post by Ms. Zafra, is a scientific article so aside from the odd mention of the internet, they provided no citations for the claims in the articles. As such they offer anecdotal support for the claims of its anti-dengue properties.

This is amazing, I thought. Could we be on the verge of a medical breakthrough? Can a lowly little native weed hold the key to licking this killer disease? I had doubts that it could kill the virus that causes dengue, but maybe it did something. Maybe it did help raise platelet count. I did some googling of my own.

According to this study, a feature of DHF in its acute phase is the inhibition of platelet aggregation. Platelets are cells in our blood responsible for clotting. From the abstract of the article Platelet function during the acute phase of dengue hemorrhagic fever, Srichaikul T, Nimmannitya S, Sripaisarn T, Kamolsilpa M, Pulgate C.:
Platelet aggregation, plasma betathromboglobulin (BTG) and platelet factor 4 (PF4) were studied in 35 children with dengue hemorrhagic fever. The suppression of platelet aggregation was demonstrated during acute phase of DHF in both shock and non-shock patients. Simultaneous with abnormal platelet aggregation, there was increased release of BTG and PF4 from platelets into plasma during the acute phase which lasted only 3-4 days after shock or subsidence of fever.
I'm not a virologist, nor am I an epidemiologist, nor any other -ist that has any relevance to this subject, but if there's anything I know it's that suppression of platelet aggregation = bad. The platelets have to be able to cause blood to clot and they do this by aggregating. That suppression of platelet aggregation is a feature of DHF in its acute phase indicates to me that suppression of platelet aggregation isn't what you want when you have dengue. So, is tawa-tawa a hemostatic as claimed in that blog post by Ms. Zafra? I went to the International Center for Science and High Technology - United Nations Industrial Development Origanization (ICS-UNIDO) website and looked up Euphorbia hirta. It does have a lot of medicinal properties:
It is regarded as medication for gastrointestinal disorders, particularly intestinal parasitotosis, amoebic dysentery, diarrhoea, and ulcer. An aqueous decoction is used for the treatment of acute enteritis and dysentery. The plant is also used in bronchial and respiratory disorders including asthma, bronchitis, and hay fever. Other uses are in diseases of the urinary system for example as diuretic; diseases of the genital apparatus (metrorrhagia, gonorrhoea, urethritis, agalactosis). It also has lactogenic properties. In ocular diseases, the plant is used against conjunctivitis and corneal ulcer. The latex of the plant is used for warts and cuts.

Other uses of the plant are affections of skin and mucous membranes (scabies, tinea, guinea-worm), as sedative, antipyretic and anti-inflammatory indications. For externally painful stings of the large brown scorpion, Bambara in Mali alleviate pain by applying the pulverised leaves. The plant has a reputation as an analgesic in severe headache, rheumatism, pains in pregnancy etc.
Nothing there about it being a hemostatic. Dengue isn't even mentioned. Then it goes on to say this under the Pharmacological Studies section:
Additionally extracts exerted an inhibitory effect on platelet aggregation and depressed the formation of carrageenin induced rat paw oedema.
citing this study. Influence of some traditional medicinal plants of Senegal on prostaglandin biosynthesis, A. Hiermann, and F. Bucar. (Abstract only. The full paper has to be purchased.)

It turns out that components in tawa-tawa actually inhibit platelet aggregation. This could be useful in other diseases, but this isnt what you want when you have DHF. You want your platelets aggregating. It may be fortunate that the decoction of tawa-tawa given to DHF patients doesnt have the concentrated amount of the platelet suppressants that the extract form contains, or else it may have done more harm than good.

Like I said, the evidence for the efficacy of tawa-tawa presented in the articles by Aspiras and Yuson, and the blog post by Zafra are anecdotal. Although I do hope that there is indeed something in tawa-tawa that alleviates the symptoms of DHF, at this time I strongly suspect that the evidence presented are of the post hoc ergo propter hoc variety. Person had DHF, person takes tawa-tawa tea, person feels better. Ergo, tawa-tawa cures DHF.

Last year, when I was in Jakarta, my daughter contracted DHF only we didnt know it was DHF at the time. My mother just told me that my daughter was running a fever and has lost her appetite. She asked my daughter if she wanted to go to the doctor and she said no, she's fine, so we didnt think it was anything serious. My mother was giving her paracetamol and I told her to keep my daughter hydrated. This went on for a few days. She developed stomachaches which my mother attributed to the fact that she wasn't eating that well. My daughter told her she was fine but my mother brought her to the hospital anyway. The doc ran a blood test and the diagnosis came that she had DHF. She had rashes all over her body and the doctor said this was a good sign that the disease was in its last legs. In other words, my daughter was able to recover from the disease on her own.

Now imagine that instead of just keeping her hydrated with water and soup, etc., my mother gave her a decoction of tawa-tawa since she saw this on TV or read it in a blog somewhere, and my daughter recovered (as she was going to do anyway). She would have attributed her recovery to the tawa-tawa. (Instead of the super-fantastic dengue-busting genes she got from me. Heh.) That's what I think is behind all this tawa-tawa hype.

Bottom line is: Be careful. Don't believe everything you read. Investigate. Try to develop an internal bullshit detector. I have to say mine is pretty acute and I wish they taught bullshit detecting in school, but it's one of those things one has to develop on one's own, since school is oftentimes just a giant bullshit factory... but that's another story.

Update, 17 September: Trawling the internet for testimonies, I came upon this one from last year. Dengue Can be Treated by a Herbal Remedy
A nurse on duty in the ICU connives with us on the use of this plant [tawa-tawa]. She even gave us instructions on how to do it, although she reprimanded us not to show our doctors we’re giving it to the patient because a patient on NGT should not be given something orally.
Also known as snake weed or cat’s hair, tawa-tawa has shown promising results based on the initial tests conducted by the health department.
It is interesting that tawa-tawa was given to the patient with the tacit approval of a health professional (the nurse), even doing so despite the fact that a "patient on NGT should not be given something orally." The nurse apparently did so presumably because the attending physician wouldnt have approved. There is also an allusion to an uncited study ostensibly conducted by 'the health department'. The blog post goes on to narrate how the mother administered the decoction.
In my case, I dip a cotton ball into the decoction, and slowly pinch the cotton ball and drop the liquid into her mouth. Perhaps she was very thirsty, the first time I drop off the liquid into her mouth, she grabbed my hands to ask for more.
The patient, thank God, recovered after being given a transfusion of platelets. As you can see, despite the sureness of the declaration in the title of the blog post, the effect of tawa-tawa was inconclusive. The patient was receiving other medication at the time and even a blood transfusion. It is probably a case of post hoc ergo propter hoc with the mother attributing her daughter's recovery to the herbal decoction.

This blog post from 2 years ago (Herbal Cure for Dengue?) was written by a doctor and expresses the same sentiment I do in this blog post: Caution. It ends with this (emphasis in the original):
In spite of its hype and anecdotal popularity, I still think drinking Euphorbia hirta extracts and concoctions is not safe.
I echo the doctor's frustration that studies have not been conducted as to the efficacy of this herb as a cure for DHF despite the fact that we have some of the highest number of dengue cases in Asia. So far the only study I have located with regards to Euphorbia hirta and its effects on platelets is the Hiermann and Bucar one linked above in which they used an extract of the plant, which to my layman's understanding indicates they used a more concentrated form of the plant's ingredients than one prepared in a decoction. Perhaps smaller doses have a different, more beneficial effect. We just don't know.


R.O. said...

Wow, this is pretty long, comprehensive. So it takes one dreaded disease to rouse you up from blogging slumber, eh?

Back to the awful subject: Now I feel guilty about my own post on it, though I only echoed claims by other, and I qualified it with no FDA/BFAD imprimatur. Now I'm terribly confused about the whole tawa-tawa business. We badly need the affirmation of science first -- medicine's best clinical evidence. No to anecdotes for now.

stuart-santiago said...

i heard/saw galvez tan endorsing tawa tawa on tv. but a day or so later new doh chief went on air and insisted that there are no clinical tests to prove efficacy re platelets. yes anecdotal evidence usually based on making wrong connection between taking a herbal concotion and getting well. so many other factors to consider besides.

Jego said...

The only way to really be sure is to conduct studies. The Hiermann and Bucar study has been around since 1994. Using that, Im thinking our scientists and medical technicians would have a blueprint of sorts for a more specific study for the effect of Euphorbia hirta on platelets. If Dr. Tan knows of any studies, he should get them published.

Everyone's looking for the DOH to take the lead in this, but let's face it: they dont have the money. The budget they have is mainly for healthcare for the less fortunate. Private institutions should take the lead in this like UST, DLSU, St. Luke's, or Makati Med.

The other thing I'd like to see is for more 'scientific thinking' in mainstream media.