MBD Series - Dengue Part 1

We are posting a series about Mosquito-Borne Diseases, along with our other regular articles. This is the first post in that series.

Disclaimer: This post is for information purposes only. This is not written by any medical doctor or government official or anyone related to the worldwide research on mosquito borne diseases. Neither is this a complete information about dengue and should not be relied on for reference. However, we have taken care to refer to reliable sources on the web, the links to which would be provided at the end of the post.

Let's start with,

Dengue

Dengue is a Spanish word, pronounced 'den-gee'. Though its origins are not clear, it's believed to have been from the Swahili phrase ka dinga pepo, that claims the disease to have been caused by evil eye. It has also been called: dandy fever, breakbone fever, break fever etc.

Dengue is the second disease to be identified as caused by virus. The first was the yellow fever.

It is found in the tropical and subtropical regions, especially, 

• the Indian Subcontinent
• some parts of the Caribbean
• some parts of the Central and South Americas
• sub-Saharan Africa
• south east Asia
• the Pacific islands

Dengue has also been identified in other parts of the world where it spread through travellers.

It is spread through mosquitoes of the Aedes genus, Aedes aegypti most known among them. The mosquitoes of this genus are known to bite during the day, dawn and dusk. Dengue is spread via human to human transmission by the females of aedes.

History

The earliest available record of a case that could have been dengue fever was found in the Chinese medical encyclopaedia from the Jin dynasty (265 to 420AD) which referred to a 'water poison' associated with flying insects.

Later, around 15th to 19th centuries AD, Aedes aegypti (the primary vector) spread to other places from Africa due to globalisation and Slave Trade. There have been descriptions about an epidemic in the 17th century.

The most plausible records of dengue epidemics available, however, from 1779 and 1780, when an epidemic swept across Asia, Africa and North America.

In a 1789 report that the US founding father Benjamin Rush, a physician, wrote on the 1780 epidemic of Philadelphia, he used first the term Breakbone fever. Rush however used the more formal Bilious Remitting Fever as the title of his report.

Confirmation of the transmission of dengue by the aedes mosquitoes came in 1906; and in 1907, dengue was the second ever disease know to be caused by a virus. Though much research has been going on for centuries, the basic understanding about dengue was completed in early 20th century.

Since the 17th century epidemic, dengue epidemics have been quite few till the Second World War. The spread of dengue since World War II is attributed to ecological disruptions. The same reason is given for the spread of different serotypes of dengue to new areas, and also for the emergence of dengue haemorrhagic fever- a more severe and probably fatal variation of the dengue fever.

Sources: Dengue Virus Net, WHO, WebMD, Wikipedia, Medindia, US National Library of Medicine, Ministry of Health and Family Welfare (Govt of India)

Fake malarial drugs in Asia and Africa

The results of a study conducted by the Fogarty International Centre at the US National Institute of Health in Bethesda, Maryland, USA about the quality of drugs used to treat malaria have shocked the world. According to this report over 1/3rd of malaria drugs tested from Asia and Africa are found to be fake or faulty.


The findings consisting of drugs sold between 1999 and 2010 in 28 different countries of Asia and Africa, were published in the June 2012 issue of the Lancet Infectious Diseases Journal. The authors write that "the economic incentives for criminals of drug falsification surpass the risks involved in production and sales".


The study was conducted mainly of samples from the southeast Asia and sub Saharan Africa.  Of the 1437 drugs from southeast Asia 36% were fake when tested and Africa had 20% of falsified drugs. Apart from counterfeiting other shortcomings were also found, including poor packaging of the drugs, resale of expired drugs in new packs and ineffective drugs. 46% of drugs in southeast Asia and 36% of sub -Saharan Africa were found to have a poor packaging. these include expired drugs that were repacked. 36% of all the samples did not have enough medication in them to fight malaria as they claimed.


Most of these countries do not have proper guidelines, regulations or laboratories for testing the medicines. The authors claim that of all the106 countries where malaria is prevalent only 3 African nations had labs capable of doing such needed tests. (Remember the controversy here that medicines banned in the west for awful side-effects were being dumped here in India?) They called for more stringent laws to fight this crime against humanity.


Source(s):
 Malariaworld
CBSnews
AllAfrica

The Sock Theory

Have you ever stood (or laid down) unprotected in a room full of mosquitoes? Have you ever noticed which part of your body the little vampires found juicy?

I have and it is mostly the legs. I had no idea why that was, though I did have a couple of theories. One is that the mosquitoes targeted any part of the body that was sticking out. Like, if you had curved into a ball and stretched out your arms, the mosquitoes bit more at the arms. The second theory is that the proximity our legs had from mosquito hideouts. Like the underside of the work desk, kitchen counter, bed, bushes in the garden, and such.

Turns out I was wrong.

15 years ago, a Dutch scientist Dr. Bart Knols made an experiment on himself. Standing in a dark room he found that the mosquitoes were more drawn to his legs. (Much like I did. Hell, that makes me a scientist too. Where’s the Nobel Prize dude?)

Dr. Knols found that our legs are four times more attractive to the mosquitoes. So if your legs were uncovered you tend to attract four times more mosquitoes, than you would otherwise. Or if you were wearing your stinking socks that you haven’t washed for, say, a week, you’d be a mosquito super-magnet. (South Chennai desperately needs one) However, this effect seemed to diminish after the legs were washed.

Though the finding did seem significant, there were no takers. That was, until now.

In 2009, a young Tanzanian, Fredros Okumu, the Principal Investigator for the Mosquito Control Project of Ifakara Health Institute, decided to use Dr. Knols’ research for his.  Procuring synthetic versions of chemical that imitate what the humans naturally emit as sweat etc. As part of a series of experiments, Okumu’s team have created a sock trap. Experimenting in real life situations in the villages, they used both such synthetic baits as well as human. The volunteers were made to sleep under mosquito nets in a hut, while the chemical cocktail was placed in another. It was so successful that the mosquitoes were attracted more to the chemicals than the humans. They also found that while the socks worked at close quarters, the chemicals worked at a long range. Okumu is convinced that most of the malarial transmission takes place outdoors, so he hopes that his research could be practically applied to control mosquitoes outdoors.  Though, it would take sometime before Dr.Knols’ and Okumu’s works were extensively used.

[Recently, Okumu’s team got funds from the Bill and Melinda Gates Foundation and Grand Challenges Canada. (BMGF do good work, but guys, technology is not always good. We don’t need bio synthesised mosquitoes that might turn our lives into a nightmare worthy of a sci-fi thriller)]

Source:  www.healthymagination.com/blog

You can follow Fredros Okumu’s blog at www.malariaworld.org/blogs/okumuf