Download Article for May, 2001 Alive magazine

Article for:
“Undercover Medicine”
Author:
David Crowe
Deadline:
January 15, 2003
Wordcount:
1200
Subject:
West Nile Virus
West Nile Virus (WNV) has been the cause of increasing concern since it emerged in the
United States in the New York City area in August, 1999 associated with a small cluster
of encephalitis and meningitis. It has justified the widespread aerial spraying of
insecticides and an army of sentinel chickens whose only job is to get bitten by
mosquitoes believed to be carrying the virus. A worried citizenry has been draining
standing pools, staying inside or covering up and applying DEET more religiously than
ever before.
The panic is hard to understand because, for more than 99% of people who test positive
for WNV antibodies, the virus will bring them less than a bad headache or a fever, and
most whose deaths are blamed on the virus are at least in their late 70’s [MMWR, 2002a].
A household survey in 1999 in the New York area found that, although there were only 7
deaths blamed on the virus that year [MMWR, 2001b], fully 2.6% of the people surveyed
tested positive, The researchers estimated that there had been 8200 infections in New
York City that year, about 1700 of which were associated with a fever. [Mostashari,
2001] However, they also noted that about one-third of this rate of fevers occurred in the
non-WNV-positive population. A serosurvey the following year estimated that only about
1/157 people in Staten Island who had evidence of a recent infection had 'serious
neurologic illness'. [MMWR, 2001a]
There has been some opposition to the spray campaigns – mainly through questioning
whether they are the best way to reduce transmission of the virus [Toxics, 2001] or
whether the health and environmental damage caused by insecticides outweighs the
benefits [NoSpray, 2002], but almost none based on questioning the viral causation
theory, and very little discussion of alternative causes for the observed illnesses.
The CDC, before making their October, 1999 pronouncement, performed antibody tests
on the cerebrospinal fluid and serum of six people with encephalitis from northern
Queens. They all tested positive for St. Louis encephalitis (SLE). Polymerase Chain
Reaction (PCR) testing found a close match with the presumed genome of West Nile
virus. Because the antibodies and antigens of SLE and WNV are believed to be very
similar, and because genetic information is considered more direct evidence, a diagnosis
of WNV was made [MMWR, 1999a]. The CDC's diagnosis was bolstered by positive
PCR tests on mosquitoes and birds, mostly American crows. [MMWR, 1999b]
Jim West was angered by the malathion spraying in his city by trucks and airplanes. He
was suspicious that the deaths of a handful of elderly people at a hot, dry time of the year,
with pollution indexes peaking, pointed more towards an environmental cause than an
infectious disease. [West, 2003]
He noted that the bird deaths started occurring weeks before human illness was first
detected. The first theory was that the deaths were due to pesticide poisoning, but lab tests
did not offer support. Air pollution was dismissed as a possibility by Ward Stone, a New
York State Department of Environmental Conservation (NYSDEC) wildlife pathologist,
even though he agreed that there was a correlation with high ozone levels, considered an
important indicator of air pollution levels.
West noted that the New York City area was the only place where reformulated gasoline
with 11% MTBE (methyl ether butyl ether) was mandated from March through October
and with 15% MTBE from November through February. This additive is intended to
make gasoline burn cleaner, and reduce air pollution in the most polluted counties, but
there are concerns about the toxicity of this product [Joseph, 1999; Joseph, 2000] and its
use is being phased out in many areas.
In the New York City area in 1999, ozone levels exceeded EPA limits more severely than
in decades. The 17 counties with this high level of MTBE in gasoline had 117 of the
WNV-positive birds in the NYSDEC database. Other counties in New York contributed a
large number of dead birds to the database, but only 2 were found to be WNV positive.
West found similar correlations in 2000 and 2001, although the number of dead birds and
the severity of human disease was lower. An increase in bird deaths had been noted since
1995, when MTBE was first mandated, but was blamed on a variety of pesticides or an
'unknown' pathogen. A British scientist, Dr. Denis Summers-Smith, has blamed declines
in sparrow populations in UK cities on the use of MTBE, and the higher concentration of
automobile exhaust in urban areas. [McCarthy, 2000] Ontario and Quebec data on bird
deaths also shows a much higher fraction of positive WNV tests in dead birds collected in
urban areas, than in rural areas. [CCWHC, 2002].
2002 found a dramatic increase in both the number and geographical spread of cases in
the United States, with the first Canadian deaths also blamed on the virus. But does this
represent a true increase in disease, or just an illusion caused by more widespread testing
and the consequent reclassification of disease that would previously have been blamed on
something else?
According to the CDC, diagnosis of WNV disease requires compatible symptoms.
However, the symptoms alone are 'usually indistinguishable from similar syndromes
caused by other viruses' [CDC, 2002]. Other mandatory components of a diagnosis are
positive serologic tests and the expectation that a pool of virus is present in the mosquito
population (‘a period when arboviral transmission is likely'). The presence of antibodies
in concert with disease usually leads to the conclusion that the virus is the cause of the
illness. Inconsistent symptoms with a positive antibody test have led some doctors to
suggest that polio-like symptoms should be added to the case definition, based on this
logic [Glass, 2002; Leis, 2002].
Tests for a virus should be grounded in experiments that have shown a very high
correlation with the actual presence of the virus. This is true for indirect tests, such as
antibody tests, and also for more direct tests, such as PCR tests. Since PCR requires a
portion of the genome to be used as the primer, it can only be relied on if this reagent is
obtained from pure virus.
In the case of West Nile Virus the standards for purification of the virus have been
reduced to such a low level that isolation of the virus can be claimed when there is no
proof that a virus is present.
A paper in the prestigious journal Science shortly after the epidemic was announced
claimed to have isolated the virus from mosquitoes and birds near New York City
[Anderson, 1999]. However, a close reading of the paper shows that isolation, in the
sense of separation of the virus from other organic materials, was most distinctly not
achieved. The experiments consisted of passing ground up crow brains or entire
mosquitoes through a filter with pores many times larger than the putative virus, checking
some of the resulting material for antibodies and also adding some to a cell culture.
‘Isolation’ of West Nile Virus was claimed when cell-killing occurred.
New infectious epidemics are claimed regularly by the CDC and similar organizations.
Most fade away, but the West Nile Virus scare is one that has captured the public
imagination. It is not clear why people want so much to believe this story, as the health
risk to the average healthy person is negligible. But the belief in the story by people who
count – the media, politicians, doctors and public health officials – is so strong that none
seem to want to question the basic science. Surprisingly quickly, a small cluster of
diseases in elderly people living in a hot, polluted city became a story of another African
virus invading America.
References
[Anderson, 1999]
Anderson JF et al. Isolation of West Nile Virus from Mosquitoes, Crows and a
Cooper’s Hawk in Connecticut. Science. 1999 Dec 17; 286: 2331-3.
Supplemented by personal correspondence in 2000.
[CCWHC, 2002]
Maps of Dead Birds Submitted for West Nile Virus Diagnosis by Health Region
in Canada.
http://wildlife.usask.ca/WestNileAlertHTML/WestNIleAlert2001ENG.htm.
2002 Nov [accessed].
[CDC, 2002]
Encephalitis or Meningitis, Arboviral (includes California serogroup, eastern
equine, St. Louis, western equine, West Nile, Powassan): 2001 Case Definition.
CDC. 2002 Sep 6.
http://www.cdc.gov/epo/dphsi/casedef/encephalitis_arboviral_current.htm
[Glass, 2002]
Glass JD et al. Poliomyelitis Due to West Nile Virus. NEJM. 2002 Oct 17.
http://content.nejm.org/cgi/content/abstract/NEJMc026043v1
[Joseph, 1999]
Joseph PM. Long story of MTBE's health hazard.
http://www.lewisvillelakepark.com/id73.htm. 1999 Jun 24.
[Joseph, 2000]
Joseph PM. Health effects from MTBE in gasoline.
http://www.garynull.com/Documents/MTBE/HealthEffects.htm. 2000 Nov 15.
[Leis, 2002]
Leis AA et al. A poliomyelitis-like syndrome from West Nile Virus infection.
NEJM. 2002 Oct 17.
http://content.nejm.org/cgi/content/abstract/NEJMc021587v1
[McCarthy, 2000]
McCarthy M. Lead-free petrol may be villain in mystery of demise of the world's
most famous bird. The Independent. 2000 Sep 11.
[Mostashari, 2001]
Mostashari F et al. Epidemic West Nile encephalitis, New York, 1999: results of
a houshold-based seroepidemiological survey. Lancet. 2001 Jul 28; 358(9278):
261-4.
[MMWR, 1999a]
Outbreak of West Nile-like viral encephalitis - New York, 1999. MMWR. 1999
Oct 1; 48(38): 845-9.
[MMWR, 1999b]
Update: West Nile virus encephalitis - New York, 1999. MMWR. 1999 Oct 22;
48(41): 944-6, 955.
[MMWR, 2001a]
Serosurveys for West Nile Virus Infection --- New York and Connecticut
Counties, 2000. MMWR. 2001 Jan 26; 50(3): 37-9.
[MMWR, 2001b]
Human West Nile Virus Surveillance --- Connecticut, New Jersey, and New
York, 2000. MMWR. 2001 Apr 13; 50(14): 265-8.
[MMWR, 2002a]
West Nile Virus Activity --- United States, November 7--13, 2002. MMWR.
2002 Nov 15; 51(45): 1026-7.
[NAFTA, 2002]
Decision of NAFTA Tribunal (Methanex vs. USA]. 2002.
[NoSpray, 2003]
http://www.nospray.org. Accessed 2003 Jan.
[Stone, 1999-2000]
Personal communication between Ward Stone and Jim West. 1999-2000.
[Toxics, 2001]
Overkill: why pesticide spraying for West Nile virus may cause more harm than
good. Toxics Action Center and Maine Environmental Policy Institute. 2001
Aug.
[West, 2003]
www.geocities.com/noxot/wnvDBcty.htm. Accessed 2003 Jan.