United States: Suffering To End Suffering: The Heroic Effort To Eradicate The North American Screwworm

Last Updated: September 23 2015
Article by Nancy E. Halpern, DVM, Esq.

By: Dr. John Richard Schrock (Guest blog)

Originally published on 01/16/2012 at http://www.naiaonline.org/articles/article/suffering-to-end-suffering-the-heroic-effort-to-eradicate-the-north-america#sthash.Y1ACCD9m.XULB2NV4.dpbs.

It was a gruesome infection. From pioneer days until the mid-20th Century, the North American screwworm was a scourge of cattle. Any little cut from thorns, any open wound left from birthing, any eye infection that wept, would soon harbor the larvae of the dreaded primary screwworm, Cochliomyia hominivorax. The adult female fly is attracted only to living flesh, and the eggs she laid hatched into maggots that burrowed into the wound. Their feeding and secretions expanded the wound, providing more space for more eggs. What was a small innocuous cut soon grew into an extensive infection that caused much suffering and could kill the animal.

And the fly was not picky. She laid eggs on wounds beyond cattle: in pigs and sheep and wild deer. The screwworm had been a natural parasite on wild animals; up to 75 percent of newborn deer died from the infections. The herds of cattle raised by ranchers merely expanded their population. And the fact that the screwworm fly infested wild deer meant that ranchers could not control the fly by herding their domestic animals through "dips." Infected wild animals would always provide a reservoir of screwworm flies to re-infect the cattle herds. Then researchers discovered a special weakness of this fly: unlike most insects, the screwworm only mated once. And nuclear technology provided a way to sterilize flies with radiation, enough to make them infertile but not enough to harm their reproductive behavior. Entomologists reared immense numbers of screwworm flies in a huge "fly factory" near Brownsville Texas and later at the southern end of Mexico. The inactive fly pupae, waiting to change from maggots into adults, were at a perfect time to be dosed with radiation and dropped from airplanes. This new technique, new in the 1950s and 1960s, was called "sterile release."

We had spread huge amounts of pesticides to kill insects. But because natural selection soon selected resistant strains, not one insect species has ever gone extinct from pesticides. But for the few species that only mate once, the distribution of huge numbers of sterile insects for several generations drives the species to local extinction. The screwworm caused huge losses of livestock across the southern United States and south into Central and South America. When the initial experimental release of sterile flies eradicated the screwworm from the island of Curacao, the U.S.D.A. launched a campaign to raise the fly, sterilize them, and drop them from airplanes in a slow sweep across the United States from Florida westward. By constantly bombarding both farm and wilderness areas with sterile flies, the few surviving fertile flies could no longer find fertile mates. The key to the process was knowing when there are no more fertile flies laying eggs. Only then could they move the battlefront forward. Since this fly only comes to open living wounds, not to dead meat, it was necessary to use "sentinel" sheep with open wounds—purposely inflicted cuts—in order to detect if there were any wild flies left. No other system would work.

The screwworm was driven from the United States and south through Mexico. The domestic and wild animals of North America and Mexico have now been free from this pest for two farming generations.

The amount of money saved annually in the cattle industry by the eradication of the screwworm approaches $400 million annually. The amount of suffering that has been prevented, both among domestic animals and among wild deer and relatives, is also immense. But only the veteran ranchers and wildlife officers remember those gruesome infections.

Just as we know that we have to suffer the momentary pain of a vaccination in order to avoid the much greater suffering of serious infectious diseases, a small number of sentinel sheep had to endure surface wounds in order to wipe out the screwworm fly. For those who would never condone this very limited suffering by the sentinel sheep, they must confront the fact that inaction would have allowed the ongoing and far more massive suffering of both domestic and wild animals in the future. Researchers are still trying to formulate a "bait" that will attract the fly and substitute for sentinel sheep, but that would be little justification for 50 years of inaction.

This also reveals a paradox about science. When we make progress in science, we often eliminate the experience base that gave us the drive to make that progress. When we suffered from contaminated water, we supported chlorine and ozone water treatment. Now, among the new generation that has always had reliably clean water, some want to end water treatment. Our children had dental cavities so we fluoridated the water and dramatically reduced tooth decay. Now many in our new generation without cavities see no reason to fluoridate the water. Teachers can teach such abstract facts—just as you can read the historical account above—but abstract discussions and historical pictures do not rise to the impact of living with widespread water-borne illness, rampant cavities and false teeth, or terribly infected cattle and deer. The rural folks of the 1950s and 1960s had the direct experiences necessary to take action to improve the condition of their animals and wildlife. With a new generation where fewer have grown up in contact with the countryside and with wildlife, it is a reasonable question to ask if today, we would still act to eradicate the suffering caused by the screwworm?

As science teachers, it is important for our students to understand that the biggest benefactors of agricultural and biomedical research with animals—are the animals themselves.

Reference: "Autocidal Control of Screwworms in North America" by R.H. Richardson, J.R. Ellison, and W.W. Averhoff, Science, Vol. 215, 22 January 1982, 361–370.
Photos from U.S.D.A. education slide series circa 1970s.

Dr. John Richard Schrock, Emporia State University, NAIA Board Member

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

To print this article, all you need is to be registered on Mondaq.com.

Click to Login as an existing user or Register so you can print this article.

Authors
Nancy E. Halpern, DVM, Esq.
 
In association with
Related Video
Up-coming Events Search
Tools
Print
Font Size:
Translation
Channels
Mondaq on Twitter
 
Register for Access and our Free Biweekly Alert for
This service is completely free. Access 250,000 archived articles from 100+ countries and get a personalised email twice a week covering developments (and yes, our lawyers like to think you’ve read our Disclaimer).
 
Email Address
Company Name
Password
Confirm Password
Position
Mondaq Topics -- Select your Interests
 Accounting
 Anti-trust
 Commercial
 Compliance
 Consumer
 Criminal
 Employment
 Energy
 Environment
 Family
 Finance
 Government
 Healthcare
 Immigration
 Insolvency
 Insurance
 International
 IP
 Law Performance
 Law Practice
 Litigation
 Media & IT
 Privacy
 Real Estate
 Strategy
 Tax
 Technology
 Transport
 Wealth Mgt
Regions
Africa
Asia
Asia Pacific
Australasia
Canada
Caribbean
Europe
European Union
Latin America
Middle East
U.K.
United States
Worldwide Updates
Check to state you have read and
agree to our Terms and Conditions

Terms & Conditions and Privacy Statement

Mondaq.com (the Website) is owned and managed by Mondaq Ltd and as a user you are granted a non-exclusive, revocable license to access the Website under its terms and conditions of use. Your use of the Website constitutes your agreement to the following terms and conditions of use. Mondaq Ltd may terminate your use of the Website if you are in breach of these terms and conditions or if Mondaq Ltd decides to terminate your license of use for whatever reason.

Use of www.mondaq.com

You may use the Website but are required to register as a user if you wish to read the full text of the content and articles available (the Content). You may not modify, publish, transmit, transfer or sell, reproduce, create derivative works from, distribute, perform, link, display, or in any way exploit any of the Content, in whole or in part, except as expressly permitted in these terms & conditions or with the prior written consent of Mondaq Ltd. You may not use electronic or other means to extract details or information about Mondaq.com’s content, users or contributors in order to offer them any services or products which compete directly or indirectly with Mondaq Ltd’s services and products.

Disclaimer

Mondaq Ltd and/or its respective suppliers make no representations about the suitability of the information contained in the documents and related graphics published on this server for any purpose. All such documents and related graphics are provided "as is" without warranty of any kind. Mondaq Ltd and/or its respective suppliers hereby disclaim all warranties and conditions with regard to this information, including all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement. In no event shall Mondaq Ltd and/or its respective suppliers be liable for any special, indirect or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action, arising out of or in connection with the use or performance of information available from this server.

The documents and related graphics published on this server could include technical inaccuracies or typographical errors. Changes are periodically added to the information herein. Mondaq Ltd and/or its respective suppliers may make improvements and/or changes in the product(s) and/or the program(s) described herein at any time.

Registration

Mondaq Ltd requires you to register and provide information that personally identifies you, including what sort of information you are interested in, for three primary purposes:

  • To allow you to personalize the Mondaq websites you are visiting.
  • To enable features such as password reminder, newsletter alerts, email a colleague, and linking from Mondaq (and its affiliate sites) to your website.
  • To produce demographic feedback for our information providers who provide information free for your use.

Mondaq (and its affiliate sites) do not sell or provide your details to third parties other than information providers. The reason we provide our information providers with this information is so that they can measure the response their articles are receiving and provide you with information about their products and services.

If you do not want us to provide your name and email address you may opt out by clicking here .

If you do not wish to receive any future announcements of products and services offered by Mondaq by clicking here .

Information Collection and Use

We require site users to register with Mondaq (and its affiliate sites) to view the free information on the site. We also collect information from our users at several different points on the websites: this is so that we can customise the sites according to individual usage, provide 'session-aware' functionality, and ensure that content is acquired and developed appropriately. This gives us an overall picture of our user profiles, which in turn shows to our Editorial Contributors the type of person they are reaching by posting articles on Mondaq (and its affiliate sites) – meaning more free content for registered users.

We are only able to provide the material on the Mondaq (and its affiliate sites) site free to site visitors because we can pass on information about the pages that users are viewing and the personal information users provide to us (e.g. email addresses) to reputable contributing firms such as law firms who author those pages. We do not sell or rent information to anyone else other than the authors of those pages, who may change from time to time. Should you wish us not to disclose your details to any of these parties, please tick the box above or tick the box marked "Opt out of Registration Information Disclosure" on the Your Profile page. We and our author organisations may only contact you via email or other means if you allow us to do so. Users can opt out of contact when they register on the site, or send an email to unsubscribe@mondaq.com with “no disclosure” in the subject heading

Mondaq News Alerts

In order to receive Mondaq News Alerts, users have to complete a separate registration form. This is a personalised service where users choose regions and topics of interest and we send it only to those users who have requested it. Users can stop receiving these Alerts by going to the Mondaq News Alerts page and deselecting all interest areas. In the same way users can amend their personal preferences to add or remove subject areas.

Cookies

A cookie is a small text file written to a user’s hard drive that contains an identifying user number. The cookies do not contain any personal information about users. We use the cookie so users do not have to log in every time they use the service and the cookie will automatically expire if you do not visit the Mondaq website (or its affiliate sites) for 12 months. We also use the cookie to personalise a user's experience of the site (for example to show information specific to a user's region). As the Mondaq sites are fully personalised and cookies are essential to its core technology the site will function unpredictably with browsers that do not support cookies - or where cookies are disabled (in these circumstances we advise you to attempt to locate the information you require elsewhere on the web). However if you are concerned about the presence of a Mondaq cookie on your machine you can also choose to expire the cookie immediately (remove it) by selecting the 'Log Off' menu option as the last thing you do when you use the site.

Some of our business partners may use cookies on our site (for example, advertisers). However, we have no access to or control over these cookies and we are not aware of any at present that do so.

Log Files

We use IP addresses to analyse trends, administer the site, track movement, and gather broad demographic information for aggregate use. IP addresses are not linked to personally identifiable information.

Links

This web site contains links to other sites. Please be aware that Mondaq (or its affiliate sites) are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of these third party sites. This privacy statement applies solely to information collected by this Web site.

Surveys & Contests

From time-to-time our site requests information from users via surveys or contests. Participation in these surveys or contests is completely voluntary and the user therefore has a choice whether or not to disclose any information requested. Information requested may include contact information (such as name and delivery address), and demographic information (such as postcode, age level). Contact information will be used to notify the winners and award prizes. Survey information will be used for purposes of monitoring or improving the functionality of the site.

Mail-A-Friend

If a user elects to use our referral service for informing a friend about our site, we ask them for the friend’s name and email address. Mondaq stores this information and may contact the friend to invite them to register with Mondaq, but they will not be contacted more than once. The friend may contact Mondaq to request the removal of this information from our database.

Security

This website takes every reasonable precaution to protect our users’ information. When users submit sensitive information via the website, your information is protected using firewalls and other security technology. If you have any questions about the security at our website, you can send an email to webmaster@mondaq.com.

Correcting/Updating Personal Information

If a user’s personally identifiable information changes (such as postcode), or if a user no longer desires our service, we will endeavour to provide a way to correct, update or remove that user’s personal data provided to us. This can usually be done at the “Your Profile” page or by sending an email to EditorialAdvisor@mondaq.com.

Notification of Changes

If we decide to change our Terms & Conditions or Privacy Policy, we will post those changes on our site so our users are always aware of what information we collect, how we use it, and under what circumstances, if any, we disclose it. If at any point we decide to use personally identifiable information in a manner different from that stated at the time it was collected, we will notify users by way of an email. Users will have a choice as to whether or not we use their information in this different manner. We will use information in accordance with the privacy policy under which the information was collected.

How to contact Mondaq

You can contact us with comments or queries at enquiries@mondaq.com.

If for some reason you believe Mondaq Ltd. has not adhered to these principles, please notify us by e-mail at problems@mondaq.com and we will use commercially reasonable efforts to determine and correct the problem promptly.