|2004 Annual Performance Report|
1 - Introduction
2 - Table of Contents
3 - Goals 1 and 2
4 - Goal 3
5 - Goal 4
6 - Goal 5
7 - Goal 6
GOAL 3: ENHANCE PROTECTION AND SAFETY OF THE NATION’S AGRICULTURE AND FOOD SUPPLY
Analysis of Results: This goal is related to food safety and the security of the
OBJECTIVE 3.1: Provide Science-Based Knowledge on the Safe Production, Storage, Processing, and Handling of Plant and Animal Products and on the Detection and Control of Toxin-Producing and/or Pathogenic Bacteria and Fungi Parasites, Mycotoxins, Chemical Residues, and Plant Toxins So As To Assist Regulatory Agencies and the Food Industry in Reducing the Incidence of Foodborne Illnesses.
During FY 2004, ARS will
using new detection and quantitation methodologies, including genomic technologies, and through the study of epidemiology, ecology and host pathogen relationships, intervention strategies, and antibiotic resistance in food producing animals, develop practices, products, and information that will reduce preharvest pathogen and toxic residue contamination of animal-derived food products. Ensure that these technologies can be utilized by regulatory agencies and/or producers to help assure safe food products.
ACCOMPLISHMENTS: If food safety pathogens are both antibiotic resistant and also hyperinvasive, they can easily make animals sick and pose an exceedingly dangerous public health threat. ARS scientists at
IMPACT/OUTCOME: Since rumen protozoa can be a reservoir for pathogens, they could be released during bouts of illness when acidic conditions kill the protozoa. This provides another intervention point (protozoa) for eliminating a reservoir of foodborne pathogens, thus improving the safety of meat and dairy products.
ACCOMPLISHMENTS: An ARS laboratory in
IMPACT/OUTCOME: The work of these two ARS laboratories with two different chemicals will help provide cattle and swine industries with practical intervention strategies that eliminate foodborne pathogens from food producing animals.
ACCOMPLISHMENTS: ARS scientists in
IMPACT/OUTCOME: These birds possessing their own genetic bacterial resistance phenomena could provide a very efficient and cost-effective means of minimizing bird colonization by food poisoning bacteria that would greatly enhance poultry food safety.
using new detection and quantitation methodologies, including genomic technologies, and through the study of crop fungal toxin relationships, production practices and expert systems, breeding targets for resistant crops, biocontrol technologies and chemical toxicity, develop practices, products, and information that will reduce preharvest fungal/toxin contamination of plant-derived food products. Ensure that these technologies can be utilized by regulatory agencies and/or producers to help assure safe food products.
ACCOMPLISHMENTS: To better understand the genetic pathways required for the formation of mycotoxins, such as aflatoxins and fumonisins, ARS scientists in
IMPACT/OUTCOME: These rapid bioassays are helping identify markers and inhibitors related to reproduction/survival, virulence, and toxin formation for the fungi that produce these mycotoxins. Already ARS scientists at
ACCOMPLISHMENTS: ARS scientists in
IMPACT/OUTCOME: Approximately 50 tons of Afla-guard® was commercially applied to the 2004 peanut crop in
ACCOMPLISHMENTS: An ARS laboratory in
IMPACT/OUTCOME: The assays offer faster, environmentally friendly alternatives to traditional instrumental methods, and ELISAs (enzyme linked immunosorbent serologic assays). They will be useful screening tools to determine mycotoxin contamination. Since mycotoxins are unevenly distributed in any contaminated plant commodity, there is a great need for methodology to determine the contamination of a large volume of potentially contaminated grains. These tests help fulfill that need.
During FY 2004, ARS will
develop innovative methods and advanced technology systems that: rapidly and accurately detect, identify, and differentiate the most critical and economically important foodborne contaminants, such as bacterial, viral, and protozoan pathogens; drug and chemical residues; and pathophysiological and processing surface contamination Ensure that the technologies are transferred to the Food Safety Inspection Service (FSIS) and the Food and Drug Administration (FDA); the Department of Homeland Security; and industry for implementation into Hazard Analysis Critical Control Point (HACCP) programs, and Good Manufacturing Practice (GMP) protocols for both large and small producers and processors.
ACCOMPLISHMENTS: ARS scientists at the
IMPACT/OUTCOME: Implementation of the entire system in processing plants will have enormous effects. It will free inspectors to evaluate only contaminated carcasses, enabling FSIS to redeploy thousands of inspectors to other safety tasks. It will also assure the increased safety and quality of the product for the consumer, thus financially increasing profits for the poultry industry.
ACCOMPLISHMENTS: ARS scientists at various locations took the lead to develop methods and technologies that have regulatory, industry, and research use. A variety of new, improved, and innovative methods were developed to detect, differentiate, type, and quantify numerous foodborne pathogens including: Campylobacter, Salmonella, E. coli O157:H7, and related E. coli, Listeria, Yersinia, C. perfringens, B. cereus, Cryptosporidium, hepatitis A, Noroviruses, Fusarium species, and products of their growth, such as toxins. New sampling methods were also developed which included a method to capture cells from any sample size and type, and enumerate without, or with minimal enrichment, currently the most time limiting step. In collaboration with
IMPACT/OUTCOME: The focus of development was utility and cost-effectiveness for the end user. Technologies were transferred to the end users, mainly FSIS and FDA, who will work with ARS to refine them for (automated) day-to-day use. Development of the microchips will allow industry to incorporate this technology into food packages before shipping. Spoilage could be monitored (by GPS) during transportation, and/or by retailers and consumers through an enzyme-based color change.
ACCOMPLISHMENTS: ARS scientists at
IMPACT/OUTCOME: Development of these tests will have a significant and immediate impact for FSIS and FDA, generating savings in materials, equipment, and labor costs. For example, in the screening of milk tankers for tetracycline, 6.4 million man hours will be saved. In addition, $1.6 million will be saved from elimination of the solvent. Current commercial toxin tests costing $12 – $20 per sample were reduced to less than $1 per test.
determine the microbial ecology and transmission of human pathogens during animal, plant, and seafood (shellfish) processing, and identify the critical control points to reduce contamination. Develop innovative postharvest intervention strategies for improving the microbial and chemical safety of foods while reducing the impact on quality and consumer acceptance. Ensure that these technologies can be implemented into HACCP and GMP protocols and have efficacy for approval by FSIS and FDA.
ACCOMPLISHMENTS: ARS scientists at the
IMPACT/OUTCOME: This research will assist egg processors and regulators providing validation of current commercial practices; providing evidence that a more effective sanitizer could potentially improve egg microbiology; and indicating that sell-by dates could potentially be adjusted allowing for marketers to reach a broader customer base. This latter impact would be particularly beneficial to producers of specialty eggs (i.e., reduced cholesterol, high omega fatty acid, cage-free, pasteurized, etc.) who are now limited to regional marketing due to concern over additional transportation time cutting into sell-by time windows.
ACCOMPLISHMENTS: The 2002 Farm Bill and the Richard B. Russell National School Lunch Act allow irradiated ground beef, on a voluntary basis, to be distributed in the National School Lunch Program (NSLP) in order to prevent foodborne illness caused by bacteria such as E. coli O157:H7. However, there were consumer concerns, based on questions from school district administrators and parents, that irradiation might change the sensory quality of the product. ARS scientists at the
IMPACT/OUTCOME: Information from the study was provided to the USDA Food and Nutrition Service, which was subsequently transmitted to schools as part of the USDA NSLP educational program on food irradiation. Orders for frozen irradiated ground beef patties have now been placed by school districts.
ACCOMPLISHMENTS: ARS scientists at various locations including
IMPACT/OUTCOME: The data transmitted to the regulatory agencies and commodity organizations facilitated the identification of critical control points during food production and processing; allowed development of alternative Hazard Analysis Critical Control Plans (HACCP) systems; and led to the design and validation of alternate pathogen intervention strategies. One critical outcome was the need to balance the cost of the intervention strategy, practicality of use by the food processing industry, and the effects on food quality.
undertake genomic and proteomic analyses of pathogens affecting food safety. Develop bioinformatic databases and tools, and predictive user-friendly models to understand pathogen behavior and acquisition of virulence characteristics under various stress conditions. Determine the key risk factors of human pathogens in foods, and evaluate systems interventions for their impact, which will allow regulatory/action agencies to make critical food safety decisions that impact public health and food security.
ACCOMPLISHMENTS: Bacteria in Campylobacter are the major cause of human bacterial associated gastroenteritis worldwide, responsible for 500 million cases of diarrhea each year. These bacteria can also cause special types of arthritis and the neurological disease Guillain-Barre which can result in paralysis and death. ARS scientists, in association with The Institute for Genomic Research (TIGR), sequenced, annotated, and compared the genome of four different Campylobacter species. This information has been used to develop and produce comprehensive Campylobacter. This is important in determining the differences among human and animal isolates of Campylobacter, and for studies of gene expression of Campylobacter exposed to relevant nutrients. Microarrays provide perhaps the most complete view of strain differences and responses to environments.
IMPACT/OUTCOME: The availability of this new genetic information will make it possible to better address food safety-related problems through the application of powerful genomic and proteomic technologies. For example, the development of better and more rapid detection techniques, the identification of those proteins essential for bacterial pathogen survival and growth in foods, and the development of data for risk assessment, will ultimately be used by FSIS, FDA and other regulatory agencies worldwide to develop strategies to decrease the public health risk and impact.
ACCOMPLISHMENTS: Listeria monocytogenes remains a significant national and international regulatory, industry, and public health risk, and economic burden. However, not all serotypes and/or strains of the bacteria have the same virulence, and capacity or ability to cause disease. In order to determine which types were critically important, ARS scientists at the
IMPACT/OUTCOME: This research has provided regulatory agencies and food producers genetic information, prevalence and ecological data, and molecular tools required for the development and implementation of the Hazard Analysis Critical Control Plans (HACCP) and regulations that provide maximum protection to consumers while limiting the number and size of product recalls.
ACCOMPLISHMENTS: ARS scientists in the
IMPACT/OUTCOME: The PMP is utilized by numerous national and international regulatory agencies and various food industries to assist in identifying specific food processing steps that can serve as Critical Control Points in HACCP systems. The predictive models are an integral part of microbial risk assessment used to support food safety measures adopted by member countries of the World Trade Organization. Combase is now a global resource for the development of new microbial models, providing the food industry with: an efficient location of specific food microbiology data; access to improved models that consider the complex nature of pathogen-food interactions; and greater transparency to microbial risk assessment.
OBJECTIVE 3.2: Develop and Deliver Science-Based Information and Technologies To Reduce the Number and Severity of Agricultural
During FY 2004, ARS will
further determine partial and full genomic sequences of important animal pathogens (target four priority diseases) to better understand the evolution of new variants, determinants of virulence, host range specificity, and factors that enable evasion from host defense mechanisms.
ACCOMPLISHMENTS: Avian influenza (AI) is one of the most feared infectious diseases. There are already several occurrences of this virus crossing the species barrier and infecting people, resulting in mortality and high economic losses to the regions experiencing new outbreaks. ARS scientists in collaboration with the National Veterinary Services Laboratories (
IMPACT/OUTCOME: The understanding of mechanisms for increased virulence of AI will improve our understanding of the pathogenesis of the virus and eventually may improve our ability to predict which low pathogenic viruses may become highly pathogenic.
ACCOMPLISHMENTS: Avian pneumovirus (APV), now classified as an avian metapneumovirus (AMPV), was first isolated from commercial turkeys in
IMPACT/OUTCOME: This scientific information suggests that the source of the new APV serotype seen in the
ACCOMPLISHMENTS: Vesicular stomatitis virus (VSV) is a viral disease clinically indistinguishable from foot-and-mouth disease, one of the most devastating exotic diseases in livestock. Outbreaks of VSV, such as the 2004 outbreak in the southwestern United States, sporadically occurs causing serious economic losses due to quarantine and the cost of associated control measures. The natural cycle of VSV in endemic areas and the factors mediating the emergence of this disease are not understood. VSV outbreaks occur at 8-10 year intervals. VSV Indiana subtypes cocal (VSIV-2) and alagoas (VSIV-3) cause outbreaks in
IMPACT/OUTCOME: ARS has determined the extent of genetic variation among VSV isolates from
ACCOMPLISHMENTS: Brucella abortus, the primary Brucella species infecting cattle, also infects other animals, including humans. Brucellosis causes abortions, significant economic losses, and is a public health threat. This disease has been nearly eradicated from cattle in the
IMPACT/OUTCOME: The discovery of unique sequences in the Brucella abortus genome provides new opportunities for developing rapid molecular diagnostic tests to identify and eradicate the different Brucellosis species that can infect our domestic and wildlife animal species.
further investigate the pathogenesis of important animal pathogens (target two priority disease) to better understand tissue tropism, disease transmission, virulence and the identification of phenotypic markers
ACCOMPLISHMENTS: Porcine reproductive and respiratory syndrome (PRRS) virus infections account for up to 15 to 20 percent of the economic losses yearly (nearly $600 million) in the
IMPACT/OUTCOME: That PRRS virus is capable of suppressing the innate immune response may explain an important mechanism this virus uses to evade the immune host response, a critical step in the design of effective biotherapeutics and vaccines to control this important swine disease.
ACCOMPLISHMENTS: One of the major concerns with Transmissible Spongiform Encephalopathies (TSEs) is that Bovine Spongiform Encephalopathy (BSE) has been shown to cross the species barrier to cause a unique TSE in human beings. Although there has not been a similar demonstration that Chronic Wasting Disease (CWD) could present any risk to human health, the BSE experience has raised many questions about the potential hazard CWD and other TSEs present for transmission to other animal species, especially domesticated livestock and wildlife. ARS scientists have focused on direct experimental challenge studies to assess the relevance of the species barrier as predictive models for future risk assessments. CWD transmission studies with cattle showed that although abnormal prion (PrPres) amplification occurred following direct CWD inoculation into the brain of cattle, none of the affected animals had classic histopathologic lesions of spongiform encephalopathy. Furthermore, only 38 percent of the inoculated cattle demonstrated amplification of PrPres. Although intracerebral inoculation is an unnatural experimental route of exposure, it is the most severe challenge possible. The results of these interspecies transmission studies suggests that cattle are either resistant to CWD or that CWD transmission may require long incubation periods of up to five years.
IMPACT/OUTCOME: These studies provide information about the clinical and pathological disease characteristics that can be expected if a TSE crosses the species barrier; thus enabling animal health specialists to recognize such situations should they occur. Additional transmission studies in the natural host will focus on determining the modes of transmission and disease development so that appropriate intervention strategies can be devised that will control the spread of these diseases.
further investigate the epidemiology of important animal diseases (target two priority diseases) to better understand their ecology and life cycle and provide effective disease surveillance to facilitate the development of control strategies and prevent disease transmission.
ACCOMPLISHMENTS: ARS was one of the first laboratories to conduct poultry-related research for both the Severe Acute Respiratory Syndrome (SARS) virus and West Nile Virus in the
IMPACT/OUTCOME: This research contributed to our understanding of the host range (identification of susceptible animal species) of two new and emerging diseases, which is vital to our understanding of disease transmission and the epidemiology of these zoonotic diseases (diseases humans acquire from animals).
ACCOMPLISHMENTS: Listeria monocytogenes is a bacterium capable of causing serious disease in humans and animals. L. monocytogenes infection of cattle and sheep can lead to disease of the central nervous system and death. Human listeriosis is a potentially fatal foodborne disease often associated with the consumption of contaminated dairy products. ARS scientists, in collaboration with
IMPACT/OUTCOME: In order to understand the epidemiology and epidemic potential of L. monocytogenes isolates, it is important to effectively access their virulence. The development of a validated model to assess virulence is a critical step towards understanding why some strains cause epidemics whereas others do not. The oral inoculation mouse model will be used to evaluate the virulence potential of genes present in epidemic strains and provide valuable insight into understanding the epidemiology of this animal and human health threat, resulting in the application of early control measures at the farm level.
During FY 2004, ARS will continue to identify genetic markers and genes (target one marker or one gene) from food animals that can be used to identify animals with disease resistant traits.
ACCOMPLISHMENTS: Mastitis is one of the most costly diseases in animal agriculture, with economic losses estimated to be $1 to 2 billion annually in the
IMPACT/OUTCOME: ARS scientists have previously established a clear link between diseases affecting dairy cows around parturition and a poorly functioning immune system. Efforts to boost the proficiency of neutrophils could have a major impact in controlling periparturient diseases, resulting in a major benefit to dairy producers by reducing economic losses due to culling of infected cows, discarding of affected milk, and cost of veterinary care. In addition, consumers will benefit from reduction of antibiotic use in the food chain and increased safety of milk through reduced pathogen contamination. The discovery of the neutrophil proteome will enable scientists to conduct experiments to identify genes associated with highly functioning neutrophils and develop genetic tests to accurately and reliably predict which cows are most susceptible to disease.
During FY 2004, ARS will continue to discover and develop novel technologies (target two high priority diseases) to detect and control diseases of food animal pests that impact animal and human health, animal production, and trade.
ACCOMPLISHMENTS: ARS played a significant role in providing the Animal and Plant Inspection Services (APHIS) with critical scientific information that enabled the USDA to take swift action when the first Bovine Spongiform Encephalopathy (BSE) case was discovered in
IMPACT/OUTCOME: Discovering the first BSE-infected cow in the
ACCOMPLISHMENTS: An ARS TSE scientist was detailed on special assignment at the request of APHIS and the Agricultural Marketing Service (AMS) to serve in a scientific advisory capacity on the
IMPACT/OUTCOME: This document is now used by AMS and the International Trade Policy group of the Foreign Agricultural Service in
ACCOMPLISHMENTS: Use of antibiotics and other drugs and chemicals in the dairy industry is one of the greatest threats to food safety. ARS scientists demonstrated that a biotherapeutic (Poly-X) to prevent mastitis in dairy cows during the dry period was at least as effective as antibiotics. At dry off, mammary quarters of 40 cows were injected with antibiotics and 40 cows were injected with Poly-X. At the time of calving, cows treated with Poly-X had less mastitis than cows treated with antibiotics. A patent application has been filed. Dairymen and organic farmers will have available a non-antibiotic compound for use during the dry period for dairy cows.
IMPACT/OUTCOME: The dairy industry needs new tools to overcome the problems associated with the use of antibiotics. Surveys indicate that at least 5 percent of bulk milk shipments and 30 percent of milk sold to consumers contains detectable amounts of antibiotics and drugs. This presents a potential human health hazard. Also, the antibiotics approved for treating mastitis are increasingly ineffective, largely due to the appearance of resistant strains. An effective “non-antibiotic” biotherapeutics to prevent mastitis during the dry period of dairy cows provides a new tool to combat this important disease without relying on traditional drug use and their potential adverse effects on the health of consumers.
IMPACT/OUTCOME: The research demonstrates the potential value of using, as an alternative to chicken inoculations, chicken embryos as a model system for evaluating NDV virus virulence. As a result of ARS’ research, information is provided more quickly on the virulence potential of new NDV isolates, and the response time for implementing control measures is decreased.
ACCOMPLISHMENTS: Poult Enteritis Mortality Syndrome (PEMS) is a highly infectious disease of young turkeys. PEMS and similar disease conditions have been reported in most regions where turkeys are commercially produced, including the
IMPACT/OUTCOME: Previously, no rapid or specific diagnostic tools were available for the detection of the viral agents associated with PEMS. The development of a highly specific and sensitive RRT-PCR assay will enable scientists to decipher the role turkey astrovirus, turkey coronavirus, and turkey reovirus play in causing PEMS and may lead to the modification of management practices to minimize the impact of this disease.
During FY 2004, ARS will continue to identify and characterize genes of insect resistance in crop plants, closely related non-crop species, and other species, to enhance opportunities for developing host plant resistance, and to incorporate such genes into commercially acceptable varieties.
ACCOMPLISHMENTS: Sustainable sugarcane production in
IMPACT/OUTCOME: These releases are significant since sugarcane in
During FY 2004, ARS will
continue to develop fundamental knowledge about insect biology and ecology that provides the foundation for strategies to exclude, detect, and mitigate pest infestations.
ACCOMPLISHMENTS: The pink hibiscus mealybug (PHM) can destroy more than 200 plant species by injecting them with toxic saliva while sucking their sap. The exotic insect pest recently invaded
IMPACT/OUTCOME: Officials with the Animal and Plant Health Inspection Service (APHIS) are using the new pheromone as a sex lure to survey the degree of mealybug pest infestations in
ACCOMPLISHMENTS: Fundamental research on fungal pathogens, including how these pathogens survive and successfully infect their insect hosts in field and greenhouse environments, will foster the development of safe, effective alternatives to chemical insecticides. Scientists in
IMPACT/OUTCOME: These results indicate the strong potential for using these agents as the key components of an integrated biocontrol program for Colorado potato beetle management.
ACCOMPLISHMENTS: Enticing new lures developed by ARS scientists at
IMPACT/OUTCOME: The molasses-derived lure is now commercially available for garden use as the product SMARTrap. The floral-based lures are in their second year of field tests. So far, use of the floral lures in a “killing station” reduced the number of alfalfa loopers by 75 percent.
continue to develop fundamental knowledge about weed biology and ecology that provides the foundation for strategies to exclude, detect, and mitigate weed infestations.
ACCOMPLISHMENTS: The winter wheat-fallow production system in the
IMPACT/OUTCOME: During the drought year of 2002-2003, this system was used. It was more competitive against weeds, improved grain quality, and yielded 20 percent more compared to winter wheat. Adoption of this alternative conservation cropping system would reduce the impact of weeds and erosion susceptibility, and increase air quality.
ACCOMPLISHMENTS: Intercrossing between rice and ecotypes of weedy red rice, a dominant weed in the southern
IMPACT/OUTCOME: These analyses may allow the rice industry to identify (or rule out) the parental lines that are responsible for development of an unwanted population of herbicide-resistant rice x red rice hybrids, a key management consideration in herbicide esistant rice systems.
continue to develop fundamental knowledge about plant disease biology and ecology that provides the foundation for strategies to exclude, detect, and mitigate pest infestations.
ACCOMPLISHMENTS: ARS has developed rapid, reliable pathogen detection and identification procedures for accurate and timely disease diagnosis for soybean rust and other high profile pathogens on the USDA Select Agent List.
IMPACT/OUTCOME: The detection assay was used by regulatory officials to accurately determine and identify a new outbreak of soybean rust in the southern
ACCOMPLISHMENTS: ARS isolated pathogenic fungi from pears shipped from
IMPACT/OUTCOME: This research protected the
ACCOMPLISHMENTS: A unique and highly virulent strain of Fusarium oxysporum was discovered in cottonseed imported from
IMPACT/OUTCOME: Identification of the highly virulent isolate from
During FY 2004, ARS will
continue to develop and demonstrate technologies for excluding, detecting, and mitigating native and invasive insect pests, including integrated pest management (IPM) and areawide approaches, and deliver IPM components and systems to ARS customers.
ACCOMPLISHMENTS: The tarnished plant bug damages a large number of crops throughout the
IMPACT/OUTCOME: These findings should increase confidence in the safety of classical biological control methods used against pest insects.
ACCOMPLISHMENTS: Many insect pests in the
IMPACT/OUTCOME: This accomplishment is important because this experimental portal (individual and grouped) and analysis suggests an effective way to compare pathogen virulence among social insects. Also, scientists in
continue to develop and demonstrate technologies, including risk analysis, for excluding, detecting, and mitigating native and invasive weed pests, including IPM and areawide approaches, and deliver IPM components and systems to ARS customers.
ACCOMPLISHMENTS: Invasive saltcedar (Tamarix spp.) shrubs from
IMPACT/OUTCOME: This research is important as it interfaces with ongoing investigations of biological control, and provides revegetation strategies for land managers that are interested in removing and replacing saltcedar. It also assists in an evaluation of the impact of the program on an endangered bird.
ACCOMPLISHMENTS: The invasive tree, Melaleuca quinquenervia, was introduced to
IMPACT/OUTCOME: The combination of the weevil and psyllid has been so successful that melaleuca is no longer threatening many of the natural areas in which it was dominant.
continue to develop and demonstrate technologies for excluding, detecting, and mitigating native and invasive plant disease pests, including IPM and areawide approaches, and deliver IPM components and systems to ARS customers.
ACCOMPLISHMENTS: ARS developed the first genetic map for the Fusarium head blight pathogen, the major fungal pathogen of wheat that produces several mycotoxins harmful to humans.
IMPACT/OUTCOME: The map has been used in genetic diversity studies, and to validate and align the genomic sequence of the pathogen.
ACCOMPLISHMENTS: ARS examined genetic variation in over 300 strains of Phytophthora infestans, causal agent of potato late blight. ARS was able to demonstrate greater levels of genotypic diversity and that population structures differed from one location to another.
IMPACT/OUTCOME: The major impact of understanding pathogen diversity will be to ensure that cultivars resistant to late blight have nonspecific resistance not limited to virulence genes in the current local populations of the pathogens.
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