The "other" side

Jeffrey A. Caldwell ecosys at
Wed Aug 2 17:54:03 EDT 2000


Thanks for putting up the whole article.  A good example of how reporting on complex
issues does not lend itself  well to "sound bites" ...

Jeffrey A. Caldwell

Neil Jones wrote:

> In article <3987D5F0.622 at>
>            cherubini at "Paul Cherubini" writes:
> > Similarly, the NABA website
> > is now making sensational,
> > worrisome, scientifically groundless claim that the mosquito
> > spraying over New York City represents:
> >
> > -"rather significant risks
> > not only to humans but to non-target species" and could be
> >
> > -"devastating to butterflies and other non-target species,
> >  and frightening and potentially harmful to many humans"
> I contend that the above is false logic and that small snippets
> of an article have been knowingly taken and used to create a misleading
> impression.  Does anyone have evidence to the contrary?
> Anyway here is the article concerned. Judge for yourselves whether the
> learned author is a "scarmongering extremist" or is he applying his considerable
> scientific knowledge to find a better solution that both satisfies
> human needs and preservation of the environment.
> The following article recently appeared in the Summer 2000 issue of
> American Butterflies
> Public Panic over West Nile Virus
>          by Michael Gochfeld, Professor of Environmental and Community
> Medicine at the Robert  Wood Johnson Medical School and School of Public
>  Health
> NABA members, even those living far from New York, could hardly have missed
> the news coverage of the great encephalitis outbreak (or "scare"). The
> discovery in September, 1999 that a new viral encephalitis had appeared
>  in the New York Metropolitan area,fostered a media campaign as well as
>  some ill-advised control efforts. The virus, genetically very similar
> to the West Nile Virus which is widespread in the Old World, caused more
>  than 50 documented cases of disease and about 7 deaths of humans (all of
> people over the age of 60), as well as widespread mortality in crows and
> sporadic mortality  in other birds. West Nile Virus belongs to a large
>  group of arthropod-borne viruses (nicknamed ARBO viruses) which includes
>  many viruses that cause more familiar forms of encephalitis as well as
> dengue fever and yellow fever.
> As do other virus, ARBO viruses require a host, in which to live. The
> primary hosts for the virus are referred to as reservoirs. Viruses are
>  sometimes spread from host to host by other animals, which are then
> referred to as vectors. For West Nile Virus, mosquitoes are the vectors
> and birds are the primary hosts, while humans are an alternate host. In
> areas such as Africa, where the virus has occurred for years, most bird
> species have developed resistance to the virus through the selective
> elimination  of susceptible individuals and the survival of those who
> could resist the infection. This evolutionary process is similar to the
>  process by which mosquito populations build up resistance to pesticides,
>  or by which bacteria develop resistance to antibiotics.
> Having studies ARBO viruses briefly in Trinidad many years ago, I have
> a healthy respect for their potential impact. Nonetheless, it is
> relatively difficult to contract an ARBO virus disease. These diseases
> are not spread directly from person to person. Rather, a person has to
> be bitten by an arthropod (usually a mosquito) that has  recently bitten
> an infected animal in whose blood the virus was already circulating.
> Not only are humans not the primary host for this virus, but human are
>  probably not even a very good host. Based upon experience with other
> West Nile  Virus epidemics, we know that typically less than one
> tenth of one percent of people bitten by infected mosquitoes develop
> any clinical signs of disease, and of those who do develop disease
> symptoms most do not develop the serious encephalitis manifestations.
> However, up to  10% of those who actually develop encephalitis may
> die of the disease.
> It is clear that there is something particularly terrifying about
> encephalitis that conjures up more frightful images than other more
> common infectious diseases, such as influenza, which each year kills
> more people than does encephalitis. Thus it is easy to understand why
> the arrival of this West Nile-like virus caused such consternation
> and alarm in the media and the public. However, in a city such as
> New York, where more  people die each day of respiratory diseases
> such as asthma and tuberculosis than died in the entire two month
> encephalitis "epidemic," it is surprising that there was such a
> dramatic response among politicians and public health workers who
> expressed an urgency to eradicate mosquitoes. Particularly fearsome
>  was the prospect that infected birds would soon be migrating and
> spreading the virus.
> Often, when people think of mosquito control, their first thought
> is pesticide spraying -- what I call "quick Henry -- the Flit"
> mentality (after a popular ad of 50 years ago). This is obviously
> what politicians thought of first when West Nile Virus was discovered
> in New York. Indeed, pesticide spraying can reduce local outbreaks of
>  mosquitoes temporarily, but populations recover quickly and over the
> long term pesticide-resistance emerges. However, serious mosquito-born
> e diseases, such as malaria, encephalitis and dengue, continue to
>  occur  in many parts of the world, requiring public health officials
>  to develop effective means of reducing risks to humans.
> The well-established public health techniques for preventing exposure
>  to mosquito-borne diseases include eliminating mosquito breeding
> places or treating them to eliminate the larval mosquitoes, the use
>  of screens or netting in homes, the use of mosquito repellants,
> reducing exposed areas of the body and reducing activities that
> expose people to mosquitoes. The use of pesticides to eliminate
> adult mosquitoes is a last resort and should be used only as an
> interim measure when and where there are large infestations of
> mosquitoes in close proximity to human populations.
> Despite these recommendations from the Centers for Disease Control
> and the World Health Organization, widespread spraying (termed
> "broadcast" spraying) was conducted in the New York metropolitan
> area -- even at a time when mosquito populations were declining
> naturally due to cool weather. Pesticide advocates asserted,
> incorrectly, that the pesticides used were innocuous to humans
> and pets and ignored outcries about the harm to non-target species.
> Advocates even pointed to the Monarch migration - the largest in
> years - as evidence that  the spray was harmless to butterflies.
> Although reports of dead birds were widely publicized, no attempt
> was made to document dead butterflies or other non-target insects.
> Television coverage emphasized the spraying and reported where
> spraying was being conducted, but rarely described all the
> above-mentioned steps that homeowners could take to reduce
> their contact with mosquitoes. There were impressive exceptions.
>  Union County, New Jersey took out a full-page advertisement in
> the Newark Star Ledger explaining why it was not spraying and
> clarifying the recommendations that empowered readers to act
> in a way that reduced their risk of mosquito bites. Experts in
>  environmental medicine at our Environmental and Occupational
>  Health Sciences Institute concluded that the media coverage
> of deaths and spraying actually distracted the public from
> these effective measures and created the mistaken impression
>  that broadcast spraying was the first choice, the preferred
> effective solution to West Nile Virus disease, and the only
> thing that needed to be done.
> In some counties, the finding of a single dead crow became a
> sufficient stimulus for county-wide aerial spraying, ignoring
>  several important features of viral disease ecology,
> avian ecology and pesticide science, and particularly ignoring
> the rather significant risks of broadcast pesticide spraying
> not only to humans but to non-target species that are of
> economic, aesthetic and ecological importance. Moreover,
> the investment in spraying diverted scarce funds from other
> public health problems.
> Although malathion (an organophosphate) and the synthetic
> pyrethroids sumithrin (Anvil) and resmithrin (Scourge) have
> relatively low toxicity to humans and other mammals and
> birds, they are not innocuous or harmless. People can become
> sick from exposure to these  pesticides as well as from the
> so-called "inert ingredients" in which they are applied.
> This is particularly true when spraying is repeated.
> Organophosphates such as malathion and pyrethroids reduce
> the activity of the enzyme acetylcholinesterase which is
> essential for normal nervous system function. This is the
> mode of action by which these pesticides kill insects and
> harm humans. For example, malathion is in the same class of
> chemicals as the nerve gases such as sarin, and workers who
>  produce malathion or blend it into final products as well
> as those who apply it, if not well-protected, can suffer
> agitation, sleepy difficulty and weakness, as well as anxiety,
>  forgetfulness and depression.
> Pesticides, even those with relatively low acute toxicity to
> adults may be more problematic in young children, with
> immature nervous systems, and in the elderly. It is also
>  a problem for those who have, or believe that they have,
> unusual sensitivities to pesticides or other chemicals.
> TV broadcasts cautioned listeners to remain indoors during
> spraying, but the time of spraying at any one location could
> not be predicted and many people could not remain indoors all
>  day on the announced day of spraying. Moreover, it is easier
> to make a house mosquito-proof than spray proof. Indeed, it is
>  well-established that outdoor air pollutants tend to accumulate
>  at higher levels indoors than out.
> The reason that my colleagues and I argued against broadcast
>  spraying are 1) in broadcast application most of the spray falls
>  on areas where the likelihood  of mosquito-human contact
> is low. Thus areas with few mosquitoes but many other non-target
> species are sprayed, as are densely populated residential areas
>  where mosquito populations are low to begin with. 2) It is not made
> clear to the public that these broad-spectrum insecticides kill many
> other insects besides mosquitoes. These include economically valuable
>  insects such as honeybees, praying mantids and ladybird beetles as
>  well as conspicuous and attractive species such as butterflies.
> Such insecticides also destroy innumerable less conspicuous insects
>  that are important components of biodiversity and are the food for
>  birds and small mammals. This, after all, was the message of Rachel
>  Carson's "Silent Spring" published in 1962, that even
> her detractors recognize as one of the most influential books of the
>  20th century.
> In weighing the risks and benefits of mosquito control, we should also
> consider the disease itself and the risk to the human population. The
> media always paired the words "lethal" or "deadly" with "West Nile" or
>  "encephalitis," reinforcing in the public’s mind the danger from the
> disease. But it would be equally appropriate to characterize West Nile
> Virus infection as "inapparent," "usually asymptomatic," or "occasionally
>  serious." Seven deaths in a population of over 10 million people
> over a one month period is certainly tragic, but pales besides the
> number of deaths from many other diseases that are addressed less
>  aggressively.
> The only human epidemic of West Nile Virus infection that has been
>  well-studied occurred in Romania in the late summer of 1996.
> The U.S. Centers for Disease Control and Prevention, certainly
> the premier infectious disease control agency in the world,
> assisted in the evaluation and control of that epidemic and
> recently published a report in The Lancet, the leading British
> medical journal.
> In that epidemic an estimated 94,000 people were infected by the virus,
> of whom about 400 developed clinically apparent encephalitis confirmed
> by virological studies. Fifteen of those people, almost all over the
>  age of 65, died. Thus, even if one is bitten by an infected mosquito,
> the risk of suffering disease is very low and the risk of dying much
> lower. Moreover, in Africa where West Nile Virus has been recognized
> for more than sixty years and where it is widespread, there have been
> very few human epidemics. In fact, West Nile Virus infection is
>  characterized by its sporadic outbreak in humans, even in areas
> where it is endemic in birds. This is likwise true of related
>  infections, such as St. Louis encephalitis and Easter equine
> encephalitis, where 30 or more years may pass between human
> outbreaks. A knowledge of these numbers is crucial in assessing the
> risk-risk tradeoffs essential to public health decisions in this area.
> Finally, emphasis has focused on dead birds, particularly dead crows.
>  Crows are among the most susceptible species to West Nile Virus in the
>  Old World and are obviously going to be a major reservoir for the virus
>  in the New World. The fact that West Nile Virus does not usually kill
> the birds that carry it is one piece of evidence supporting the
> hypothesis that it recently arrived in North America, where our
> crows and other birds have yet to develop any immunity. However, in
> order for the disease to be sufficiently widespread in the birds to
> cause a number of bird deaths, and in order for there to be enough
> infected birds to infect enough mosquitoes to produce an epidemic,
> the virus had to be present in the bird population for many months,
>  perhaps even for years. In southern Europe the virus was present
> for several years before the Romanian outbreak.
> This means that the virus is probably already fairly widespread
> in birds, not  just in crows. Birds, including crows, range
> widely and are not cognizant of county barriers. Thus a bird
> that dies in county A today may have been infected in county B
> last week. Thus, to base county-wide control programs on a single
> dead crow is inappropriate.
> It is interesting to contrast the experience and response in
>  New York versus that in New Jersey, which has a statewide
> network of County Mosquito Control Commissions, established
>  long ago to control New Jersey’s state "bird," the mosquito.
> New Jersey has extensive experience in conducting surveillance
> programs for viral encephalitis, including the strategic
> placing of sentinel chickens in cages in area where mosquitoes
> are prevalent. The chickens are then regularly tested for virus
>  activity. This surveillance program successfully reduced human
> and equine infection by Easter equine encephalitis and St. Louis
> encephalitis even though these viruses continued to be active in
>  bird populations.
> Although New Jersey abandoned this program years ago because the
>  yield seemed to be low, it quickly re-instated surveillance when
> news of West Nile Virus arrived. Moreover, the county Commissions
> have been vigilant in keeping infestations of mosquitoes in check
> through the use of Integrated Pest Management which reduces breeding
> areas in proximity to human activities, introduces natural predators
>  to keep mosquito populations in check and uses judicious
> spot-applications of larvicides. Spraying to control adult
> mosquitoes is considered a last resort to be used only when
> local infestations become a serious nuisance or health threat.
> Local health officials, the media, and the public, need to be
> aware of these facts and need to be reminded lest our vigilance
> is reduced and serious disease outbreaks occur. The seductiveness
>  of aerial pesticide spraying, devastating to butterflies and
> other non-target species, and frightening and potentially harmful
> to many humans, should be the last, not the first, approach to
> controlling disease spread.
> West Nile Virus is likely to surface again this year, heralded
> by dead crows and great fanfare, and the pressure to use broadcast
>  spraying may be powerful indeed. Improved surveillance will show
> that the virus occurs over a much wider area than just the New
>  York metropolitan region. Spraying is likely to begin much earlier in
> the season - June rather than August. If this happens, it is
> likely that the impact on butterflies and other non-target
> species will be severe.
> Alternatively, public health agencies can focus on the
>  less flashy, but more effective,strategies for reducing
> mosquito populations. Integrated Pest Management has been very
> successful in reducing mosquitoes in New Jersey and elsewhere
>  where it has been tried. It can virtually eliminate the risk
> of an ARBO-virus disease, without eliminating many other
>  valuable or aesthetically pleasing creatures and without
> jeopardizing human health.
> --
> Neil Jones- Neil at
> "At some point I had to stand up and be counted. Who speaks for the
> butterflies?" Andrew Lees - The quotation on his memorial at Crymlyn Bog
> National Nature Reserve

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