**An Analytical Study of the Perceptions, Prevention Srategies,
Treatment and Economic Impact of Equine West Nile Virus**

**Robert Galvan, MPH, MS, DrPH~.,~ Associate Dean and Assistant
Professor**

**Department of Health Management & Policy, School of Public Health,
University of North Texas Health Science Center at Fort Worth, Fort
Worth, Texas 76107-2699, USA**

**E-mail: <bgalvan@hsc.unt.edu>, Tel: 817-735-2372, FAX: 817-735-0324**

**Antonio Rene, Ph.D., Assistant Professor**

**Department of Epidemiology, School of Public Health, University of
North Texas Health Science Center at Fort Worth, Texas 76107-2699, USA**

**E-mail: <arene@hsc.unt.edu>, Tel: 817-735-0327, FAX: 817-735-0324**

**S. Bae, Ph.D., Assistant Professor**

**Department of Biostatistics, School of Public Health, University of
North Texas Health Science Center at Fort Worth, Texas, 76107-2699,
USA**

**E-mail: <sbae@hsc.unt.edu>, Tel: 817-735-5162, FAX: 817-7352314**

**K.P.Singh, Ph.D., Professor and Chair**

**Department of Biostatistics, School of Public Health, University of
North Texas Health Science Center at Fort Worth, Texas, 76107-2699,
USA**

**E-mail: <ksingh@hsc.unt.edu>, Tel: 817-735-0490, FAX: 817-7352314**

**Abstract:** Since the introduction of the West Nile Virus (WNV) in the
United States in 1999, WNV has been the cause of disease and deaths in
humans, wild birds, zoo birds, and horses. In 2002, more than 15,000
equines in 40 states were diagnosed with illness associated with WNV.
Horses are infected with the WNV more often than humans or any other
mammal. It is becoming one of the fastest growing health threats to
horses nationwide. Positive reports for WNV were announced in 2002,
which prompted an increase in public education and equine vaccination
recommendations. Although much has been reported on the economic impact
of WNV on human health and hospital care facilities, documentation is
lacking on these issues in the equine population. In this study, we
examine WNV cases in the equine population in Texas in order to better
understand the distribution of clinical disease, signs, treatments and
outcomes. The results of the survey suggest that there could be a need
for WVN education among veterinarians in areas of prevention, control,
and treatment. Values for lost horses were not solicited in the survey,
thus, a total economic impact could not be completely estimated.

**1. INTRODUCTION**

With the introduction of the West Nile Virus (WNV) into the United
States in 1999, WNV has been the cause of disease and deaths in humans,
avian and equines. Since mosquitoes are the primary vector that
transmits the virus and with wild birds as the reservoir of the virus,
it has the enormous potential to affect livestock and poultry. In 2002,
more than 15,000 equines in 40 States were diagnosed with causes of
illness associated with WNV and approximately one third of these horses
died or were euthanized (Campbell et al, 2002). While the virus may
infect humans and horses, there is no documentation that infected horses
can spread the virus to uninfected horses or other animals. Migrating
birds appear to play a major role in spreading the WNV infection and
disease and it is becoming one of the fastest growing health threats to
horses and equines nationwide.

Horses are infected with West Nile virus more often than humans or any
other mammal resulting in one of the fastest-growing health threats to
horses nationwide. Once a horse is infected, the virus multiplies,
potentially causing the severe illness. This leads to a disruption of
the central nervous system and swelling of the brain. The worst form of
the disease is fatal encephalitis or inflammation of the brain.

While there is no specific treatment or cure for West Nile Virus,
prevention is the key strategy in dealing with this life-threatening
disease. Horses that are vaccinated and receive boosters at the
designated intervals have the highest level of protection against the
West Nile Virus. Millions of horses already have been safely vaccinated;
however, millions more are still at risk. Many of the horses that do
become infected will not show any symptoms at all and are able to shed
the virus on their own within eight days.

Because the mosquitoes that infect horses are the same mosquitoes that
infect humans, disease prevention and control efforts are essential. In
addition, Public Health has always played a critical role in disease
surveillance and control of both animal and human populations.

The virus was first isolated and identified in 1937 from an infected
person in the West Nile district of Uganda (Campbell, Marfin, Lanciotti
and Gubler, 2002). After it was first isolated, infrequent outbreaks in
humans were reported in Israel and Africa, mostly in soldiers, children,
and healthy adults. These outbreaks were associated mainly with
low-grade fever, headache, myalgia and fatigue. An increase in the
frequency of WNV outbreaks, as well as increased clinical severity of
the disease with notable neurological involvement and increase in
mortality were noted in the mid-1990's. Until 1999 the spread of the
virus was limited to the Eastern Hemisphere with wide distribution in
Africa, Asia, the Middle East, and Europe, and was not seen in the U.S.
until the summer of 1999 (Campbell et al, 2002; Mostashari, Bunning,
Kitsutani, Singer et al, 2001). During 1999-2001, WNV spread throughout
much of the eastern half of the U.S. and Southern Ontario in Canada.

A broad range of mammalian species are susceptible to WNV. In the U.S.
at least nine mammalian species including humans, horses, cats, rabbits,
skunks, squirrels, chipmunks and two species of bats were found to be
naturally infected with WNV. The outbreak of the disease in horses
across a ten-state region in 2001, and experimental studies in horses,
suggests that the dead-end host for the WNV is the equine population
(Campbell, et al, 2002).

1.1 *Epidemiology of West Nile Virus in Equines*

Since the first case of WNV in the U.S. in 1999, the virus has been
migrating across the country. By mid-June of 2002, the WNV had traveled
to the eastern portion of Texas. Since then, it has been reported in
mosquitoes, birds (such as blue jays and crows), horses, and humans in
Texas. There has also been a continued westward movement of the virus.
(TDH, 2000).

The prevalence of the WNV in horses in Texas has been declining since
2002. Below are annual summaries provided by the Texas Department of
Health Zoonosis Control Division.

Table 1: West Nile Virus Statistics

  ------------------------------------------- --------- --------- ---------
  Annual Summary of WNV Cases                 2002      2003      2004

  Bird                                        519       534       5

  Human                                       202       437       0

  Mosquito                                    260       1058      0

  Horse                                       1699      717       3

  Other                                       0         11        0

  TOTAL                                       2680      2757      8
  ------------------------------------------- --------- --------- ---------

 *Source: Texas Department of Health Zoonosis Control Division (2004)*

Horses are affected by WNV much more often than any other domestic
animal. Forty percent (40%) of all cases of WNV in horses result in
death, although most horses tend to recover ("West Nile Virus," 2003).
Clinical signs of WNV in horses vary considerably, and may include
ataxia (lack of coordination), circling, stumbling, falling, weakness or
partial paralysis of limbs, muscle twitching (especially around the nose
and lips), head drooping, lethargy, unresponsiveness, hypersensitivity
to touch or sound, drooping lips, smacking, chewing, grinding teeth,
falling asleep inappropriately, recumbency, and transient fever. Most
horses continue to eat and drink normally, even when recumbent.
Urination and defecation are usually normal. Many horses with WNV
infection remain bright and alert and do not exhibit obvious signs (UC
Davis CEH, 2004). However, it is important not to presume that horses
with clinical signs of encephalitis have WNV.

A definitive diagnosis requires ruling out other important diseases with
similar neurological signs. Rabies, botulism, Equine Protozoal
Myeloencephalitis (EPM), and Eastern (EEE), Western (WEE), and
Venezuelan (VEE) Equine Encephalitis are examples of other diseases with
neurological signs that may be confused with WNV. A positive diagnosis
of WNV can be made only by examining blood from infected horses
(Fontaine, 2002).

1.2. *West Nile Virus in Texas*

Prompted by discovery of WNV in the New England area of the U.S. in
1999, the Texas Department of Health (TDH) announced expansion of their
mosquito monitoring system. The TDH Laboratory tests over 200,000
mosquito specimens a year as part of the early warning system for
encephalitis in an effort to prevent human outbreaks (TDH, 2001). The
TDH Infectious Disease Epidemiology and Surveillance division initiated
a plan to add WNV testing to seven counties with existing monitoring
systems and expand monitoring to eight additional counties ("*Texas
Department of Health*", 2000). Most of the areas collect and monitor
mosquitoes during peak mosquito season, from May to November, but some
do monitor every month. The targeted areas were within migration paths
of birds traveling from the northeastern United States through the Gulf
Coast. The eastern one-third of the state receives concentrated
surveillance. Infected birds, which serve as a reservoir for the virus,
could be detected from samples sent to the TDH lab by county health
departments, military installations, universities, and other mosquito
control programs ("West Nile Virus", 2003).

Birds particularly affected by WNV are blue jays, crows and hawks. Blue
jays in the Houston area first tested positive for the virus in June
2002 and one month later, two blue jays in Dallas County were found to
carry WNV. In August, TDH reported that the Center for Disease Control
and Prevention confirmed that seven persons living in Texas had tested
positive for WNV. Four of those positives were from Harris County, two
from Orange County and one from Jefferson County.

With horses identified as being most susceptible to contracting WNV,
vaccination of the Texas equine population was encouraged by TDH early
in 2003. TDH veterinarian, Joe Garrett noted that a vaccine that is
approximately 95% effective in preventing WNV in horses was available
(TDH, 2003). He added that horses should initially receive two
injections 3-6 weeks apart with an annual booster thereafter. Protection
against the disease would begin approximately 3-4 weeks following the
second initial injection. WNV had not been shown to adversely affect
other domestic animal populations.

1.3. *Economic Impact*

The economic impact of WNV on the equine industry is not an area that
has received much research attention; however, in academic and public
health circles, the issue has been of concern since the rapid spread of
the disease was apparent. In looking specifically at the equine
industry, very few studies have been published outlining the economic
effect WNV has had on this industry. Knowing the increasing spread of
the disease and potential health outcomes in humans and equines, the
economic impact seems an important area to discuss. The most extensive
study to date is one that was done in Colorado and Nebraska in the year
2002. This was a critical study in that it was the first time
researchers had put a quantifying number on the cost of WNV to equines.

For the study period of 2002, Nebraska had 1100 and Colorado had 378
reported and confirmed cases of equine WNV for a total of 1478. These
numbers may be low due to the low prevalence of laboratory confirmation
in this population. The estimated cost of lost revenue due to the horses
not being able to be used during time of treatment and recovery is
approximately \$163,000(APHIS, 2002). "The cost attributed to death or
euthanasia of 432 equines in Colorado and Nebraska was estimated at
\$600,660" (APHIS, 2002 p.2). The veterinarians surveyed were asked to
estimate the cost for treatment in mild, moderate and severe cases.
Their estimates were \$200, \$400 and \$250 respectively. Factoring in
the number of cases for Colorado and Nebraska, the total estimated cost
for all treatments was \$490,844. (APHIS, 2002, p.3)

Treatment and prevention in human and equine populations have been
frequently debated in recent years. Cost analysis on the effectiveness
of the vaccine versus the costs is an issue that all states affected by
WNV have questioned. For equines, the effectiveness of vaccines had
previously been discussed. Concerning cost, an average vaccine treatment
of two (2) shots costs \$50 (Lavine, 2003). For the affected horse
owners in Colorado and Nebraska, estimates are that they spent a
combined \$2.75 million dollars in 2002 on prevention (AVMA, 2003, p.1).
This number assumes that a mere 25% of the equine population was
vaccinated.

In Texas, there are over one million horses accounting for a value of
\$4.2 billion dollars. The impact of the horse industry on the Texas
economy is over \$11 billion dollars each year (Gibbs, Potter, Jones,
1998). These are important aspects to understand when one is dealing
with a disease such as WNV.

2\. METHODOLOGY

The objectives of this study are to: (1) provide information regarding
the perceptions, knowledge, concerns, and treatment of the West Nile
Virus by veterinarians in Texas; and (2) to determine the economic
impact of the West Nile Virus on the equine population in Texas. This
study was a collaborative effort of the Texas Veterinarian Medical
Association (TVMA), the Texas Department of Health (TDH), and the
University Of North Texas Health Science Center School Of Public Health.
The TVMA licensure office provided the veterinarian contact information.

# 

2.1. *Survey Design*

The survey instrument was developed by reviewing survey instruments that
had been used in previous research. Two questionnaires were reviewed for
relevance to the current study: the "2002 Veterinarian Survey" conducted
by the Colorado State University Animal Population Institute in
collaboration with the Colorado State Veterinarian Office; and the "West
Nile Virus Survey" from the Harvard School of Public Health Project on
Public and Biological Security. Questions from both studies were
selected and modified for the current survey. Ease of response, brevity,
and options for modes of responding (i.e. online and via mail) were
considered in the content development of this tool. To preserve the
confidentiality of the respondents, no identifying information was
included in the survey instrument. The research study was granted Exempt
Status by the University of North Texas Health Science Center's
Institutional Review Board.

The instrument consisted of 13 close-ended questions and 1 open-ended
question. The one open-ended question was a component of the survey used
to determine major West Nile Virus issues for Texas veterinarians.
Several of the questions addressed knowledge and perceptions about the
West Nile Virus, education and training, and the effectiveness of
prevention methods (vaccination regimen). Other questions were
specifically designed for veterinarians who had diagnosed cases of
equine West Nile Virus during the previous year (2003).

The target population consisted of all licensed and
practicing/non-retired veterinarians in the state of Texas (4,177) as of
the year 2004. Veterinarians who were surveyed practice in the various
urban, suburban and rural counties throughout the state and are licensed
by the Texas State Board of Veterinary Medical Examiners (TSBVME) who
supplied the contact information and mailing list.

2.2. *Data Collection and Analysis*

Survey participants had the option to complete an on-line survey or to
return a completed hard-copy survey to the University of North Texas
Health Science Center by US mail. All of the surveys were mailed by
February 25, 2004. The surveys were sent with a stamped business reply
envelope in order to increase the response rate.

Statistical analyses were performed by using SPSS version 11 (SPSS Inc,
Chicago, IL).

The methods used for analysis of WNV data were descriptive statistics
including summations and frequencies and logistic regression analyses.

## 3. RESULTS

With 700 of 4,177 surveys returned, 73.4 % (514/691) veterinarians
believed that they are knowledgeable about WNV (Table 2). Only 49.7 %
(348/691) believed that they are receiving or have received enough
training/education concerning WNV (Table 2). The vaccination regimen is
believed to be effective and reliable by 56.1 % (393/691) of the
veterinarians (Table 2).

Table 2. Response to Knowledge, Education, and Vaccination

  ------------------------- --------------- -------------- --------------
  Response                  Q1 n (%)        Q2 n (%)       Q3 n (%)

  Strongly agree            131 (19.0)      49(7.1)        80(11.6)

  Agree                     383 (55.4)      299(43.1)      313(45.3)

  Neutral                   75(10.9)        192(27.7)      277(40.1)

  Disagree                  84(12.2)        142(20.5)      15(2.2)

  Strongly Disagree         18(2.6)         12(1.7)        6(0.9)

  Total                     691             694            691
  ------------------------- --------------- -------------- --------------

Q1:I believe I am knowledgeable about West Nile Virus.

Q2: I believe veterinarians are receiving enough training/education
concerning West Nile Virus.

Q3: I believe the vaccination regimen for the equine West Nile Virus is
effective and reliable.

There were 1256 cases of equine WNV reported confirmed via laboratory
testing. There were also 766 horses reported that were not confirmed via
laboratory testing. Among the 2,022 diagnosed cases, 257 were vaccinated
against WNV prior to illness and 159 cases were vaccinated after signs
of illness.

A total of 441 horses died as either a direct cause of the disease or by
owner or veterinarian elected euthanasia. In 301 horses the owners
elected euthanasia; in 117 horses the veterinarians elected euthanasia.
The most common criteria used to decide euthanasia in these horses was
prolonged recumbency as reported by 44.2 % (87/197) of the
veterinarians. Other criteria included prolonged course of disease
without resolution of clinical signs (21.8 %), quality of life (13.7 %),
perceived cost of treatment (13.2 %), and other (7.1 %).

Table 3: Response to Major Issues Concerning West Nile Virus

  ------------- --------- ---------------------- --------- ----------- ---------
  Concern                                                              

  Vaccination   n=227     Education              n=312     Vector      n=223
                                                           Control     

  Vaccination   123(54)   Public Education       120(39)   Mosquito    123(55)
  Program                                                  Control     

  Horse Owner   39(17)    Client Education       63(20)    Human Risk  60(27)
  Compliance                                                           

  Vaccine       37(16)    Veterinarian Education 34(11)    Bird        12(5)
  Efficacy                                                 Migration   

  Vaccine Cost  25(11)    Small Veterinarian     41(13)    Zoonotic    21(10)
                          Education/Non-Equine             Potential   

  Apathy        3(2)      General Education      41(13)    Wildlife    7(3)

                          Economic Impact        13 (4)                
  ------------- --------- ---------------------- --------- ----------- ---------

(%)

In questions to be answered only by veterinarians that diagnosed a case
of WNV, 52% (233/448) of the veterinarians did not recommend prevention
strategies to equine owners (Table 6). Of the 215 veterinarians that
recommended prevention strategies, 94.8 % believed that they are
knowledgeable about WNV. Of the 233 veterinarians that did not recommend
prevention strategies, 50% did not believe they are knowledgeable about
WNV. Also 61.2% (275/449) of the veterinarians did not provide any
recommendations on mosquito mitigation or other control strategies to
their clients. Among the 213 veterinarians that recommended mosquito
mitigation or other control strategies, 76.1% believe that veterinarians
are receiving enough training and/or education concerning WNV. However,
of the 233 veterinarians that did not recommend control strategies, only
37.8% believe they were receiving enough education. Among veterinarians
that recommended mosquito mitigation or other control strategies, 94.2%
believe that they are knowledgeable about WNV. Also 70.8% (194) of
veterinarians that did not recommend mosquito mitigation or other
control strategies also believe that they are knowledgeable of WNV.

Table 4. Response to Prevention and Control Strategies "

  -------------------- ------------------------- -------------------------
  Response             Q10 (n=176)               Q11 (n=176)

  Yes                  172 (97.7)                134(76.1)

  No                   4 (2.3)                   42(23.9)
  -------------------- ------------------------- -------------------------

> (%)
>
> Q10: Have you recommended prevention strategies in the treatment of
> the equine population owned by your clients?" among veterinarians that
> treated equine cases
>
> Q11: Have you provided any recommendations on Mosquito mitigation or
> other control strategies?" among veterinarians that treated equine
> cases

According to the survey results 97.2% (171/176) of veterinarians that
treated WNV in 2003 agree that they are knowledgeable about WNV.
However, the percentage drops to 65.5% (343/524) of veterinarians that
have not treated WNV. Among these veterinarians, 78.4% (138/176) believe
that veterinarians are receiving enough training and/or education
concerning WNV. In veterinarians that did not treat WNV only 40.1%
(210/524) believe that they are receiving enough education. Also 81.8 %
(144/176) of veterinarians that treated WNV believe that the vaccination
regimen is effective. Only 47.5 % (249/524) of veterinarians that did
not treat WNV believed that the vaccination regimen is effective.

Table 5. Logistic Regression Analysis

  --------------- ---------------------------------------- ------ ----------
                  Question                                 OR     95% CI

  Did Not Treat   I believe I am knowledgeable about West  0.06   (0.02,
  WNV/Treated WNV Nile Virus.                                     0.14)\*

  Did Not Treat   I believe veterinarians are receiving    0.18   (0.12,
  WNV/Treated WNV enough training/education concerning            0.28)\*
                  West Nile Virus                                 

  Did Not Treat   I believe the vaccination regimen for    0.20   (0.13,
  WNV/Treated WNV the equine West Nile Virus is effective         0.31)\*
                  and reliable                                    
  --------------- ---------------------------------------- ------ ----------

\* p\< .05, OR: Odds Ratio, CI: Confidence Interval

Logistic regression analyses were conducted to determine the magnitude
of the difference between veterinarians that did not treat WNV as
compared to those that did with respect to the first three survey
questions (Table 5)**.** All three analyses were statistically
significant at the p\<.05 level. Veterinarians that did not treat WNV
for approximately 95% less likely to agree that they were knowledgeable
about WNV. It was also observed that those that did not treat WNV were
82% less likely to agree that veterinarians are receiving enough
training. In addition, 80% of the practicing veterinarians that did not
treat horses for WNV did not agree that the treatment regimen for WNV
was effective and reliable.

The cost of the vaccination regiment for the equine WNV was reported by
62% (269/434) of the veterinarians to be \$25 or less. Only 1.4% (6/434)
reported that the average cost of the vaccination was \$101 or greater.
In questions pertaining to cost of treatment, 59.9% (109/182) of the
veterinarians reported that treating a mild case of WNV cost less than
\$200, 70.6%(127/180) of the veterinarians reported that treating a
moderate case of WNV cost less than \$600, and 59.9%(100/167) of the
veterinarians reported that the cost of treating a severe case of WNV is
more than \$701

Anti-inflammatory products were used in 63.47% (146/230) of mild WNV
cases treated by veterinarians. Other treatments included antibiotics
(13.04%), fluids (5.65%), steroids (2.17%), and other (15.65%).
Anti-inflammatories were used in 57.76% (160/277) of moderate cases.
Other treatments included fluids (9.03 %), antibiotics (7.8%), steroids
(5.77%), and other (19.86%). Anti-inflammatories were used in 44.2%
(156/353) of severe cases. Other treatments included fluids (13.3%),
antibiotics (7.9%), steroids (6.0%), and other (28.6%).

In 1998, Texas A&M University estimated the horse population in the
State of Texas to be over 1 million, with an estimated value of
approximately \$4.2 Billion or \$4,200 per horse. It is estimated that
the State has over 280,000 horse owners with a total investment in the
horse industry of \$13 Billion. Additionally, it is estimated that the
horse industry has an economic impact of over \$11 Billion dollars to
the Texas economy (Texas A&M University, Animal Science, 1998).
Utilizing these figures, tables 15 and 16 provide a conservative
estimate of the economic impact to the horse owners and the horse
industry on two parameters: vaccination and mortality.

Utilizing a conservative estimate of one million horses in the State of
Texas, tables 15 and 16 reflects a conservative twenty five percent
(25%) vaccination rate at a cost of twenty five dollars (\$25) per
vaccination regime. Based on this estimate, the economic impact to horse
owners for these two years (2002-2003) was \$12.5 million. Based on data
in table 1, the number of WNV cases in Texas for 2002 and 2003 was 1,699
and 717, respectively (Texas Department of Health Zoonosis Control
Division 2004). With an estimated forty percent (40%) mortality rate
(Johnson, 2002), the number of horses that died or were euthanized in
Texas in 2002 and 2003 as a result of the WNV was estimated at 680 and
287, respectively. With an estimated cost of \$4,200 per horse, the
economic impact from WNV to horse owners in 2002 and 2003 was
\$2,856,000 and \$1,205,400, respectively, for a total of \$4,061,400.
Based on these same figures, the total estimated economic impact
associated with WNV in Texas specifically resulting from costs related
to vaccination and mortality was \$16,561,400. This estimate does not
take into account animal replacement and training costs. Based on the
estimation, It is recommended that additional studies are warranted to
grasp the full economic impact of WNV on the equine industry and the
Texas economy.

Table 6. Estimated Economic Impact of WNV -- 2002 and 2003\*

  ------------- --------------- ---------- ---------- ------------- -------------
                Estimate per    Number of             Total         
                Horse           Horses                Estimated     
                                                      Impact        

                                2002       2003       2002          2003

  Vaccination   \$25            250,000    250,000    \$6,250,000   6,250,000

  Mortality     \$4200          680        287        \$2,856,000   \$1,205,400

  Total                                               \$9,106,000   \$7,455,400
  ------------- --------------- ---------- ---------- ------------- -------------

\*Source: Texas Department of Health

# 

# 4. DISCUSSION

The objectives of the study were to gain understanding of WNV cases
among the Texas equine population, of veterinarians' perceptions,
beliefs and knowledge of WNV, and of the economic impact of WNV on the
equine population in Texas. It is estimated that the horse population in
Texas is in excess one million horses (Gibbs et al, 1998). Results from
the survey suggest that from this large population of horses, there were
over 2,000 cases of equine WNV statewide in 2003. Of the 2,022 cases of
diagnosed WNV, only 24 horses died as a direct cause of the disease. In
418 cases, euthanasia was elected either by the owner or the
veterinarian. These results suggest a case fatality rate of 40% which is
normal in comparison to others equine WNV studies in the U.S. Since no
prior studies have been conducted on the equine population in Texas,
these results can serve as a benchmark for future studies.

The results of the survey suggest that there could be a need for WVN
education among veterinarians in areas of prevention strategies,
control, and treatment. Only half of veterinarians in this survey
recommend prevention strategies to their clients. Less than half of
veterinarians who have not treated a case of WNV believe that they are
receiving enough education on the disease. Approximately half of the
veterinarians who responded to the survey believe that the vaccination
regimen is effective in the treatment of WNV. Results from the survey
also indicate that only a small percentage equine were vaccinated after
signs of illness. Future studies should be conducted to examine owner
knowledge and beliefs on WNV vaccinations and prevention strategies.

These statistics show a very meaningful connection between the
veterinarians who treated cases of WNV and their perception of
self-knowledge (Question 1). A significant link was also discovered
between those veterinarians who did not treat cases of WNV and those
that believe that veterinarians are receiving enough training education
concerning WNV. However, chi-square results of Question 3 (effectiveness
and reliability of the vaccine) and those who treated West Nile Virus do
not indicate a significant relationship.

The economic impact of WNV on the Texas equine population was also
examined. The 2003 Colorado and Nebraska study estimated the economic
impact by multiplying the number of horses lost by the average purchase
price of a horse in 1998. Gibbs et al. (1997) estimated that the average
purchase price of a horse in Texas for the year 1997 was \$5,249,
however, later figures indicate an average cost of a horse in Texas to
be \$4,200. Therefore, using this formula, it can be estimated that the
economic loss due to WNV fatalities in 2003 totaled \$1,205,400.
Moreover, adding the cost of vaccination and the estimated fatality
cases, it can be approximated that equine WNV cost owners an estimated
\$7,455,400 for 2003.

This study is limited because the information in the surveys was
self-reported, however, this is a valid method of studying veterinarian
attitudes. Also, many of the values given for number of cases in the
survey were ranges; thus the exact number of cases could not be
determined. Moreover, many veterinarians responding to the survey
identified themselves as having a small animal practice only. Full
economic impact of WNV in equines could not be determined because value
of the horses that were euthanized or died was not solicited in the
surveys.

Understanding the effects and treatments of WNV is essential in
controlling this disease in the equine population. More research and
education on WNV in the equine population is needed to prepare
veterinarians and equine owners. Estimates of yearly cases of equine WNV
should be collected in order to understand the impact of the disease and
its changing patterns. Secondly, vaccinations and prevention strategies
should also be surveyed in order for researchers to understand their
effectiveness. Moreover, study results indicate that more education is
needed to encourage vaccination and other preventive measures. There is
an opportunity to fill this void by providing educational collaborative
efforts between Veterinary Medicine and Public Health. Potential studies
could also include surveys of owners' beliefs of prevention strategies
and treatment methods of WNV in equines. The economic impact of WNV in
equines must be fully examined to show the full impact of the disease on
the state of equine were vaccinated against WNV prior to illness and an
even smaller percentage.

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