U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 close



Research
                Research Home
                            National Programs
                            Research Projects
                            Scientific Manuscripts
                            International Engagement
                            Scientific Software/Models
                            Databases and Datasets
                            Office of Scientific Quality Review
            Media
                News & Features
                            Multimedia
                            Briefing Room
                            Down on the Farm
                            Press Room
                            Science in Your Shopping Cart
                            Scientific Discoveries
                            Tellus
                            Under the Microscope
            About ARS
                About ARS Home
                            Staff Directory
                            Labs and Research Centers (Map)
                            Headquarter Offices
                            Organizational Chart
                            Employee Services (REE Employees Only)
                            Office of Outreach, Diversity, and Equal Opportunity
            Work With Us
                Work With Us Home
                            ARS Vacancies at USAJOBS
                            Careers at ARS Information
                            Scientific Collaborations
                            Extramural Agreements
                            1890 Faculty Research Sabbatical ProgramSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home News & Events News Articles Research News 2002





- ARS News & Events
- AgResearch Magazine
- Image Gallery
- News
- Search News & Events
- Pesticide Drift May Endanger Pollinators
- ARS Seeks a Fire Ant Fix
- Scientific Discoveries 2024
- ARS Featured Photos
- Down on the Farm
- Facebook Live Events
- Food and Nutrition Research Briefs
- News Archive
- Science in Your Shopping Cart
- Scientific Discoveries
- Social Media
- Under the Microscope
- AgResearch magazine
- ARS at Work
- ARS Memorial Lectures
- ARS Science Hall of Fame
- Citrus Disease (Huanglongbing)
- Contact Office of Communications
- Plant Hardiness Zone Map
- Mobile Apps
- Public Affairs Contacts
- Publications and Other Resources
- USDA Blog
- Videos

Archived Page
 This page has been archived and is being provided for reference purposes only. The page is no longer being updated, and therefore, links on the page may be invalid.
 Water-borne Pathogen Not Always What It Appears To Be By Sharon DurhamApril 23, 2002 The water-borne parasite Cryptosporidium parvum was thought to be a single species that infects humans and more than 150 animal species. Now Agricultural Research Service zoologist Ronald Fayer and his colleagues have described a unique species of this pathogen, C. canis, originally found in dogs. C. canis can be transmitted by--and infect--dogs, humans and cattle. Scientists originally thought the new species was C. parvum. Identifying this and other Cryptosporidium species can help pinpoint potential sources of infection. Cryptosporidium is a single-celled parasite that lives in the intestines of animals and people. This microscopic pathogen causes a disease called cryptosporidiosis, which is characterized by mild to life-threatening diarrhea. Disease is spread by a form of Cryptosporidium called an oocyst, which is excreted in the feces of infected humans and animals. The tough-walled oocysts survive under a wide range of environmental conditions. Studies by Fayer and cooperators at the Animal Waste Pathogen Laboratory in Beltsville, Md., found that C. canis oocysts differ markedly at the molecular level from those in known species of Cryptosporidium. Based on this and other research, scientists now believe C. parvum is not one woven cloth, but something of a quilt made of different blocks. Each block represents a biologically distinct and unique organism. Using powerful, new genetic tools, it is becoming clear that there are numerous Cryptosporidium species previously thought to be C. parvum. The slight genetic differences that distinguish one species from another have great implications for predicting which host species may become infected by the pathogen. Other scientists have found, within the C. parvum classification, several unique genotypes associated with specific hosts such as humans, mice, pigs, marsupials, dogs and ferrets, based on genetic data. ARS is the U.S. Department of Agriculture’s chief scientific research agency.


Return to top


Research
                            Media
                            About ARS
                            Work With Us


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov