Archive for the 'Science' Category

Dengue: the virus strikes again… and again

August 24th, 2010

denguedist
Distribution of dengue infestations (yellow) and dengue epidemics (red). (image source: [1])

News groups have reported a surge of dengue infections around the globe. One case was reported today in Australia (in the tropical Northern Territory), the first in over 70 years [2]. India has 434 new cases reported this week, with 1 death [3]. The Philippines was not spared, with reports of the number of deaths on the increase, from 387 people in 2009 and currently 315 people so far in 2010 since January [4].

Dengue has been recognized as a human disease for over 200 years. Life-threatening syndromes associated with dengue are dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). In the past 20 years, these diseases “emerged” as the most important vector diseases of humans worldwide [5]. To say they have “emerged” means that although these diseases have been around for a long time, the dynamics of these diseases have changed significantly such that it has become more difficult for us to control and prevent their occurrence. For instance, though we know that the epidemics are influenced by seasonal changes (wet weather being more favourable to the mosquitoes serving as vectors for the disease), the gaps of time between epidemics have shrunk from 10-15 years into as little as 3-5 years [6]. As with most infectious diseases, when the dynamics of infection change, we in turn should respond to these changes in order to control them, and protect ourselves from the harm they cause.

There are 4 different serotypes (genetic classifications) of dengue. A person can then be infected with dengue up to 4 times, since there is no cross-immunity. This poses a challenge to developing a vaccine that can be equally effective against all 4 serotypes.

denguevirus Dengue virus. left: immature, right: mature (image source:[1])

What are the perceptions of the Filipino on dengue? If you ask some persons in a Manila street today what they know about dengue, you’d probably get some pretty straightforward responses, such as…

… it being a severe disease of children caused by mosquito bites,

… They might associate some faces of local government officials with ‘fogging’ activities [7] in their areas to fight dengue.

… They may have heard in the news that a number of people have died as a result of dengue.

If they didn’t know anyone close to them who was affected by dengue, chances are they really wouldn’t go much further than these responses. If you go further into the provinces you are more likely to meet someone who knows a person infected with dengue. Currently, dengue cases on the rise are noted in the Visayas and Mindanao. An assessment of the knowledge of students in Negros Oriental [8] showed that most respondents are unaware of the importance of indoor control measures (as opposed to ‘high-profile’ outdoor ‘fogging’, which generates a lot of publicity for politicians).

Fogging doesn’t work. Outdoor spraying to kill adult mosquitoes is less effective because not all the mosquitoes are outdoors. What remains most effective in control of dengue is to kill larvae: destroy the breeding sites of mosquitoes by draining water-filled containers and removing rubbish appropriately. Unfortunately, there is no consistent program in the Philippines to maintain a standard of sustaining the eradication of mosquitoes. Why? With such labor-intensive work comes the need for MONEY.

No money, no information campaign, no training, no end to the mosquitoes.

Without sustaining such projects mosquitoes reestablish themselves in a matter of a few years. If only there was constant funding so that such projects are not abandoned in developing countries such as ours, then these simple but highly effective control measures can continue. A program in Vietnam [9] was effective in controlling dengue. It involved support from the central government and action from the local community. Larval breeding sites were destroyed. The peculiar but effective use of Mesocyclops (a kind of crustacean which feeds on larvae of Aedes aegypti) to control the mosquitoes larval development in water-filled containers was successful to eliminate dengue. There has been recommendations that these techniques are transferrable to other South East Asian nations [10].

It is unfortunate that most efforts to fight dengue, even though highly effective, in tropical developing countries have either waned or been abandoned. Only in times as today where news banners headlines on deaths from dengue do we cast a spotlight on the problem. Sadly, such an attitude of nonchalance and apathy whenever there is no sensationalism contributes to the success of this disease. Mosquitoes become more cunning in hide-and-seek, the virus acquire more vigour against our therapies and efforts to find a vaccine. The wet weather comes and goes as do outbreaks, but our attitudes seem to remain the same. While disease dynamics become more efficient by virtue of evolution, our own complacence makes our battles against them a losing one.

The least we can do as citizens is to abide by ‘cleanliness’ standards to not contribute to the problem. An extra step would be to lobby for an effective AND consistent program to control the mosquito population. A concerted plan must be on the ready to prevent another inevitable outbreak.

[1] Mackenzie JS, Gubler DJ and Petersen LR. Nature Medicine 10, S98 – S109 (2004)

[2] http://www.abc.net.au/news/stories/2010/08/24/2991507.htm?section=justin

[3] http://timesofindia.indiatimes.com/city/delhi/34-new-cases-of-dengue-tally-434-now/articleshow/6423546.cms

[4] http://gulfnews.com/news/world/philippines/dengue-deaths-rise-in-philippines-as-authorities-deny-outbreak-1.671753

[5] Gubler DJ. Clinical Microbiology Reviews, July 1998, p. 480-496, Vol. 11, No. 3

[6] Gubler DH and Clark GG. Am. I. Tmp. Med. HYg.. 50(6) Suppl. 1994, pp. 50-60

[7] http://www.pcij.org/blog/?p=1201

[8] http://www.searo.who.int/en/Section10/Section332/Section1985_9819.htm

[9] Kay B and Vu SN. Lancet. 2005 Feb 12-18;365(9459):613-7.

[10] http://www.ecotippingpoints.org/our-stories/indepth/vietnam-dengue-mosquito-copepod-biological-control.html

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Centipede follow-up

May 26th, 2008

Years ago, I wrote about a centipede bite I experienced. There have been a steady number of comments building up over the years, and I hope I had compiled the websites I had looked up that time about centipedes. I remember finding a site with pictures of different centipedes. I cant seem to find the website anymore, but I tried to find a picture of the species of centipede that had bred in our garden.

I wasn’t very descriptive before in my last post, aside from the length of the centipede (the one that bit me – TOTBM). The usual centipede I would imagine had I not seen TOTBM, would be the long red kind (Vietnamese centipede, Scolopendra subspinipes). But TOTBM had a grayish fat body, with yellow legs, a huge orange head and tailtip. I found several pictures that looked like TOTBM, one called the Tiger centipede (also known as Asian giant-red headed centipede, Scolopendra heros). I had shivers just looking at different ‘real pictures’, but I can live with a cartoon to attach here:
(centipede experts, welcome to correct the names I found)

Somewhere I had also read that centipedes are cousins of crustaceans (e.g., crabs, lobsters) owing to their segmented bodies (Phylum: Arthropoda). There are about 8,000 different species of centipede, and the most colorful ones are in the tropics (such as of course, the Philippines). I haven’t met anyone who actually ‘collects’ centipedes, but there are who do. Wonder what they think, and how they can surpass the tingly sensation that most of us get from just seeing these wiggly creepy slithery crawlies.

*shiver shiver*

In Wikipedia, it says that the hazards of a centipede bite to humans are mostly just great pain due to the poison/venom (as we all know now). However, people who are known to have allergies to bee stings have are in risk to be in greater danger. This also applies to small animals and children.

So may our pets and babies be safe and kept very far away from them!!! They’re gone from our house now (or so I think… and hope!) ever since we had the place cemented over. I can remember there were just sooooo many baby centipedes (as small as less than a cm long) and a few big ones (an inch or two long). And TOTBM which was of course the largest one I saw, more than half a foot! But yeah just to say, my mom was the one who killed it by pouring hot water on it when it got trapped!

science talk

May 12th, 2008

Fabio and I gave a joint presentation for the Centre for Health Informatics, about our work on tuberculosis.

Look at this page… (scroll to halfway down the page)

http://www.chi.unsw.edu.au/CHIweb.nsf/page/Past+Talks

That’s another hit for me on the internet, hehe. And free name-dropping for UP Diliman too!

Your kid will be a techy

June 13th, 2007

Recent studies shows that kids using technology are getting younger and younger. From an average age of 8.1 from 2005, it dropped to 6.7 years old for 2007.

From the article

The average age at which children begin using consumer electronic (CE) devices has declined from 8.1 years in 2005 to 6.7 years in 2007, according to The NPD Group’s recently released report, Kids and Consumer Electronics Trends III. The report, which provides insight into the penetration of consumer electronics in kids’ lives today and how this has changed since the earlier 2005 and 2006 studies, measures device usage dynamics and trends.

Come to think of it, we are living in a technology driven world. Access to these technologies are not unusual anymore. US households have an average of 2 laptops and a desktop at home. MP3 players are abundant and iPods are quickly becoming a necessity rather than a luxury. Cellphones are given to elementary children by their parents nowadays whereas I bought my own cellphone when I already have a job.

The first ‘technology’ that I was exposed to (apart from the tv set) is the Atari System I had. Then I moved to Nintendo Family Computer then to desktop computers when I was in high school. Internet access when I was already in college.

It’s a bit frightening that children have access to these technologies if not properly supervised by their folks. Technology is always a double-edged sword, I just hope children will be properly educated of the harms and benefits of being exposed to the new world at the earlier age.

science news: Purple Earth

April 11th, 2007

Scientists have found evidence that prior to being a predominantly green planet, Earth was purple!

Somewhat loose discussion:

This has something to do with how membranes of organisms absorb and reflect wavelengths of light from the sun’s rays. We all learned about chlorophyll in photosynthesis in grade school. Scientists are proposing the idea now that at one time, the Earth was riddled with organisms that absorbed green light and then reflected red+violet = purple light. But there existed some purple-absorbers who could not compete with the abundance of green-absorbers. To survive, the evolved with an ability to absorb purple, and reflect green. They somehow maintained survival, and eventually emerged victorious in dominating the environment.

So how useful is this information, aside from being strikingly adorable to purple-color lovers?

Well, for one thing, on our search for life in other planets, it means not always searching for the same observable things we see on Earth at present, like the dominance of color (green).

[If you want to look up more information about these news snippets I write about, I'll start putting some keywords to look out for]

Keywords: retinal, halobacteria, archael bacteria

science news: Gender-related issues

April 10th, 2007

Not all of these are specific to humans, but nonetheless, just as interesting:

Female stem cells work better. (also here) Remember the buzz about stem cells (and cloning) before? Stem cells are present in our bodies, and they are capable of renewing themselves so that they show promise in medical therapies for many diseases. There are now indications that stem cells from females are much more effective in regeneration than those from males. The sturdier sex they say ;)

Females do better if they wait a while. This is in context with a particular type of birdcalled Green wood hoppoes. For them, the theory of having offspring early in life maximises the number of offspring you will have does NOT apply. At least not for the female. It seems that the birds, when they care for their young, end up being isolated from the social group, and hence become physiologically “less fit”, causing them to die much earlier. So the much more mature female birds who are more adapted to “being alone” are able to reproduce much more in their lifetime since they live longer. Doesn’t this make you think about the analog in female human life?

[off-topic] Funnily enough though, this piece of news also reminds me of the “True Love Waits” seminar we had in high school. I dunno about you guys, but I think private schools, especially the sectarian ones [though they claim they are non-sectarian.. they are!!] have a tendency to indoctrinate kids too much that they turn out as biased people with an unleveled sense of judgment. I don’t really know at this point whether I want my kids to turn out this way.

Fewer men are being born in recent years. Researchers cannot explain exactly why this is so, but their latest findings in a study in the US and Japan show that there are less male than female births. They are looking into environmental and nutritional (and also late age) factors that cause men to be “less likely” to father boys. Sex ratios are important characteristics of a species that serve as indicators of the “health” of our kind. Not to alarm anyone, but this seems to me that in the long run, women will be fighting over scarce men. Paano na ang freedom to choose?

Very scary thought.

science news: Texas Hold ‘Em

April 7th, 2007

Theoretical physicist Clement Sire is soon to publish his paper on poker tournaments, in particular the dynamics of the game Texas Hold ‘Em.

I first had a view of this game when I watched the World Series of Poker that Ajay was watching. It’s different from the classic poker game where all cards are held by players, since in Texas Hold ‘Em some cards are laid on the table.

Anyhow, back to Sire. Using intuition and clever statistics, he formulated a model that predicted the maximum stack (earnings) a leading player will hold as well as an estimate of how long a tournament will last. Both of these he says are functions of how many initial players there are and some behavioral aspects of players that he quantifies.

How cool is that?

What is also interesting is that organisers of these tournaments figured out that the minimum bets should be made to increase exponentially as the game progresses. Sire’s model explains this perfectly. Like he says, it is amazing intuition, even sans the math approach, that the organisers are able to figure this out. Fundamental observations pay off it looks like?

The techniques he uses are typical of analysis used in evolutionary dynamics used in biology.

Amazing.

=====Sydney Weather: Gloomy and Rainy====

Click to see San Diego casinos.

science news: Miniature dogs.

April 7th, 2007

Oi Bantay! =)

Well the context of this post is not entirely on the guard dog Pinoys usually have, but specifically for the toy dog-lovers. Tiny breeds as the minipinscher, toy poodle, pomeranian, terriers, etc.

Several articles yesterday, one of which was in yesterday’s LA Times , talked about how small dogs are now potentially useful in research about growth factors in humans that can eventually lead to insights about cancer and skeletal diseases. Isn’t that interesting?

Scientists found a particular piece of regulatory DNA that was present in all small dogs. It is an amazing find, and how this supposed “disadvantage” of being small survived evolution can be explained by the domestication of these tiny canines by humans.

‘Coz aren’t tiny dogs just so sweet?

But the funny thing about it is they found the same gene present in Rottweilers. Maybe they’re really tiny dogs in big costumes.

======= Iron-rich food consumed today : BROCCOLLI.=======

Losing hair? Maybe it’s time for a hair transplant.