Thursday, March 31, 2016

A Is For Aedes aegypti: Whining Killers vs Silent Spring #AtoZChallenge

Spraying DDT, 1958
General Background

Brazil, currently a hotspot for Zika, reported an almost 50-percent increase in cases of dengue fever reported over a three-week period in January 2016. Dengue is transmitted by the Aedes aegypti mosquito, which also transmits Zika, chikungunya and yellow fever.

Aedes aegypti is now found in most tropical and sub-tropical regions of the world. It has distinctive white markings on legs and thorax. A. aegypti are particularly well-suited to living alongside humans as they prefer to stay (and bite) in shady/indoor areas, and to breed and lay their eggs in stagnant water. They are particularly drawn to water containing the chemical signature of bacteria involved in the decay of leaves and other organics in water. So outdoor showers and lavatories, trash cans, flower pots, wash tubs - all can provide a breeding ground for the mosquitoes, even if they hold as little as a tablespoon of stagnant water. The eggs themselves can remain viable even after spending up to a year in a dry state (during drought, for example) and thus hatch a new swarm after a dry spell or
cold season.

Chikungunya, dengue (sometimes referred to as "break bone disease" because of its associated pain) and now Zika have been rising in incidence in the Americas. Zika has proven particularly worrisome because of evidential links to births of babies with microcephaly.

A. aegypti used to be referred to as the yellow fever mosquito. The United States suffered its last major outbreak of yellow fever in 1905, in New Orleans. Yellow fever was never endemic to the US - it arrived via port traffic and trade, which is why most epidemics occurred in port cities like New Orleans and Philadelphia. Once here, the disease was spread via the native mosquito populations.

Malaria was once a problem in the US as well. Ever wonder how those two scourges were eliminated in the US?

Observation, sanitation, fumigation

The link between yellow fever and mosquitoes was known and pretty much proven by 1900. During the last yellow fever epidemic in the US, Walter Wyman, the surgeon general of the U.S. Public Health and Marine Hospital Service, was appointed by Roosevelt to institute a public health campaign. Ships were quarantined and fumigated. Workers fumigated the city, screened the cisterns and water tanks, and destroyed breeding grounds for mosquitoes. Fines were given to residents who failed to comply with public health measures.

The same methods, with the addition of improved drainage, plumbing, public reservoirs and the use of window screens in housing helped to reduce malaria as well. The introduction of chloroquine and especially DDT after WW2 completed the process of eliminating malaria in the US and much of Europe.




DDT

DDT was synthesized in 1874 and its properties as an effective insecticide established in 1939. It was used extensively during World War Two to combat typhus, malaria and dengue. In 1945 it began its use as an agricultural pesticide.  DDT played a large role in the elimination of malaria from Europe and North America. However, there were mounting concerns over its effects on health and the environment. Rachel Carson explored these concerns in her famous book Silent Spring, published in 1962. The book argued that pesticides, particularly DDT, were poisoning wildlife and the environment and were endangering human health. Silent Spring became a best seller, and launched the environmental movement in the United States.  DDT was banned in the US in 1972, with some exemptions for public health uses. It was also banned in many other countries.

"The Stockholm Convention on Persistent Organic Pollutants, which took effect in 2004, outlawed several persistent organic pollutants, and restricted DDT use to vector control. The Convention has been ratified by more than 170 countries and is endorsed by most environmental groups. Recognizing that total elimination in many malaria-prone countries is currently unfeasible because there are few affordable or effective alternatives, the convention exempts public health use within World Health Organization (WHO) guidelines from the ban." *

 "It's hard to overestimate the impact that DDT's early success had on the world of public health," writes Malcolm Gladwell for THE NEW YORKER. 
 
DDT saved millions of lives during its decades of use in countries all over the world.

Other Vector Control Methods

Aedes aegypti can be genetically modified with a self-limiting gene that prevents the offspring from surviving. Lab produced male mosquitoes, which do not bite or spread disease, are released into the environment to mate with the blood-feeding females. Their offspring then inherit the self-limiting gene and die before they can reproduce or spread disease as adults.  This method, however, opens a can of worms as we can not always predict the future effects of gene modification on a species.

Radiation can also used to sterilize adult males, which reduces the number of viable offspring in the mosquito population. An expensive and somewhat laborious way to combat a prolific breeder.

Proper sanitation, elimination of  mosquito breeding areas and the use bed nets and window screens are effective tools but prove expensive and problematic in large, poverty-stricken urban environments, especially since the mosquitoes can breed in as little as a tablespoon of water.

Dangers of DDT vs human toll of new epidemics

“That concern about DDT has to be reconsidered in the public health context,” said Dr. Lyle R. Petersen, director of the division of vector-borne diseases at the Centers for Disease Control and Prevention. He said the damage to fish and wildlife stemmed from widespread outdoor use of DDT in agriculture, not the use of small amounts on walls inside homes to kill mosquitoes. **

While the World Health Organization has declared Zika a global emergency, most of the recommendations I've read in the media amount to things like asking that women in the affected regions forgo pregnancy in the next year, that pregnant women from other countries avoid travel to affected areas, and that women of childbearing age use repellents (like DEET), wear protective clothing and use contraception. Some of these recommendations are problematic and disruptive to daily life. Certain faiths discourage or outright prohibit the use of birth control. Tropical heat is not conducive to wearing clothing which covers the entire body. Repellents may be unavailable for purchase or prohibitively expensive for those already struggling to afford food.

Children born with microcephaly often face a shortened lifespan along with a multitude of physical and mental impairments. Families of affected children will bear the burden of struggling to secure proper medical care along with the cost burden of providing that care. The socio-economic fallout from Zika may be felt for many years, if not decades. Add to that the additional health problems resulting from an explosion of dengue and (possibly) chikungunya, and we have the makings of a medical catastrophe.

Half a century ago, DDT was applied copiously and sometimes indiscriminately. We now know that it persists in the environment for years and makes its way into the food chain and the bodies of organisms. Since then we have also come a long way in our understanding of toxins, as well as safer means of application.  We know that continued exposure to a particular pesticide often causes insects to develop immunity; but since DDT has not been used in many countries for 20+ years, the current mosquito population probably has no resistance. And DDT has always been recognized as an extremely effective insecticide.

In 2006, The World Health Organization (WHO) began recommending the use of indoor residual spraying (IRS) of DDT in malaria epidemic areas and in regions with constant and high transmission rates.

From the WHO news release: “The scientific and programmatic evidence clearly supports this reassessment,” said Dr Anarfi Asamoa-Baah, WHO Assistant Director-General for HIV/AIDS, TB and Malaria. "Indoor residual spraying is useful to quickly reduce the number of infections caused by malaria-carrying mosquitoes. IRS has proven to be just as cost effective as other malaria prevention measures, and DDT presents no health risk when used properly.”

“Indoor spraying is like providing a huge mosquito net over an entire household for around-the-clock protection,” said U.S. Senator Tom Coburn, a leading advocate for global malaria control efforts. “Finally, with WHO’s unambiguous leadership on the issue, we can put to rest the junk science and myths that have provided aid and comfort to the real enemy – mosquitoes – which threaten the lives of more than 300 million children each year.”  Read the entire 2006 WHO news release here.

     Update April 4, 2016:  The World Health Organization (WHO) announced that there is “a strong scientific consensus” that the Zika virus is a cause of both the birth defect microcephaly and the neurological disorder Guillain-Barré syndrome





*Wikipedia
**Pollack, A., NYT (January 30, 2016). "New Weapon to Fight Zika: The Mosquito". Retrieved February 13, 2016

Additional sources:
Szabo, L, USA Today (March 4, 2016) "Study Provides 'Strongest Evidence Yet' Linking Zika, Birth Defects". Retrieved  March 4, 2016

Roland Mortimer. "Aedes aegypti and dengue fever". Onview.net Ltd, Microscopy-UK

Moyers B (September 21, 2007). "Rachel Carson and DDT". Retrieved February 13, 2016

Phillips D , Washington Post (February 12, 2016). "Brazil Reports Explosion Of Dengue, A Bad Omen For Spread Of Zika Virus" Retrieved February 13, 2016
 


Monday, March 21, 2016

I Have No Theme But I Do Have Some Tasty Morsels... #AtoZChallenge

   


I have no theme for the challenge this year, which some readers might find appealing (like reaching into the Mystery Prize Box) and others might find alarming (like reaching across the cafeteria line for the Mystery Meal Of the Day). So I thought I'd post a phrase or sentence from some of the pieces (many are stories or memoirs) that are finished. Hopefully, some of you will be back for more.

A - The United States suffered its last major outbreak of yellow fever in 1905, in New Orleans.

B - I like my crossbite. It might be slightly bovine, but who doesn't feel a sense of peace while watching a cow contentedly chewing?

C - The remains of the soldiers were discovered in 1932 when Morris Frederick was digging a cellar on a property at Locust Street.

D - Alkhurma hemorrhagic fever, for example.

E - Pack up your troubles and your ironing board and smile...smile...smile...

F - "Aren't we all asking 'Where's my elephant?' "  

G - "Look honey, I'm wearing my dead man's pants today!" 

H - Had we been alone, I might have grabbed those shiny Gee Your Hair Smells Terrific scented locks and smashed her head against the lockers.

I - The flaw in that line of reasoning is that I never repeated a single stupid act. There were hundreds of others to choose from.

N -  There were murmurings of magic, but magic is an anfractuous thing, a tumbling of whispers, reason, legends and faith.

P - Out of the corner of my eye, I saw the aforementioned photographer sneaking toward the coffin.

S - jawn

T - Dirt is a battlefield.

U -  Half of a scarlet bra was dangling cheerfully from the hastily zippered front compartment.

V - And that's why, on future trips, we ended up eating sandwiches along the highway and having to tiptoe into the litter-filled scrub to pee.

W - "But make sure that I am gone before you enter. Mukulaal mininkeeda joogta miciyo libaax bay leedahay...a cat in her house has the teeth of a lion."

Z - Items in the display include an axe used to chop up a girlfriend's furniture after she fell in love with someone else, jewelry, underwear, and assorted broken things associated with broken hearts.

Check out A to Z Challenge theme reveals here

Thursday, March 10, 2016

Quick Update #AtoZChallenge

   
      I've signed up for this year's A to Z challenge but managed to miss every deadline so far. Instead of a theme this year, I'll be doing random entries ranging from flash fiction to non-fiction to "slightly fictionalized memoirs".
      My blog has been languishing due to a. time constaints   b. laziness  c. shortened attention span  d. the dog ate my laptop  (pick any two).
      Hopefully the challenge will help me to re-focus on writing. If not, well...I'm contemplating fencing lessons this summer.  There are sure to be some good stories generated after placing a weapon (of sorts) in my hand.
      What about you? What's new, how's the writing scene going for you, are you signed up for A to Z, any interesting plans for the summer?