Life cycle of Toxoplasma gondii PDF

(PDF) The Life Cycle of Toxoplasma gondii in the Natural

Figure 2.5 the life cycle of Toxoplasma gondii Transmissions Toxoplasmosis appears to be transmitted by:- Congenital transmitted 1- Transplacental transmission which often leads to severe and life long disabilities in the infected infant. Acquired transmitted 1- Ingestion of Oocyts excreated in the faces of infected cats tha environment. Figure 1. Life cycle of Toxoplasma gondii: the classical life cycle between intermediate hosts (IH, rodents), definitive hosts (DH, felids) and environm ent (E, soil) is.

The life-cycle of Toxoplasma gondii reviewed using animations Márcia Attias1,2*,Dirceu E. Teixeira3,Marlene Benchimol 4,Rossiane C. Vommaro1,Paulo Henrique Crepaldi 1 and Wanderley De Souza1,2 Abstract Toxoplasma gondiiisaprotozoanparasitethatisthecausativeagentoftoxoplasmosis,aninfectionwithhighpreva The life cycle of T. gondii includes three infective stages, which are tach yzoites with a cresce nt shape to oval, found in acute infection, a nd is transmitted through t h Toxoplasma gondii (T. gondii) is considered as one of the most successful parasites in the world. This success is first illustrated by its worldwide distribution, from arctic to hot desert areas, including isolated islands and in cities [1]. T. gondii is also among the most prevalent parasites in the global human population, with around one third of the population being infected [2]

Life-cycle of Toxoplasma gondii in cat. a Ingestion of prey containing tissue cysts. b The cyst wall is digested in the stomach and intestines, liberating bradyzoites. c Bradyzoites invade epitelial cells of the intestine. d In the enterocytes bradyzoites divide by schizogony giving rise to merozoites Life Cycle. T. gondii primarily exists in three forms: oocysts, tachyzoites, and bradyzoites. Oocysts are only produced in the definitive host, members of the family Felidae. When passed in feces and then ingested, the oocysts can infect humans and other intermediate hosts. They develop into tachyzoites, which are the rapidly multiplying. Life cycle of toxoplasma gondii. @article{Hutchison1969LifeCO, title={Life cycle of toxoplasma gondii.}, author={W. Hutchison and J. F. Dunachie and J. Siim and K. Work}, journal={British Medical Journal}, year={1969}, volume={4}, pages={806 - 806} } W. Hutchison, J. F. Dunachie, +1 author K. Work; Published 1969; Medicin

Select up to three search categories and corresponding keywords using the fields to the right. Refer to the Help section for more detailed instructions Toxoplasma gondii has a complex life cycle with multiple forms. Intermediate hosts such as humans are infected by sporozoites in oocysts or bradyzoites in pseudocysts whereas the sexual stages occur in the intestine of the definitive host, feline species Life cycle of toxoplasma gondii. Br Med J 1969 ; 4 doi: https://doi.org/10.1136/bmj.4.5686.806-b (Published 27 December 1969) Cite this as: Br Med J 1969;4:806. Article. Related content. Metrics. Responses. Peer review. This is a PDF-only article. The first page of the PDF of this article appears above

Life cycle of Toxoplasma gondii in the North African context Toxoplasmagondiiisanobligateapicomplexanintracellular protozoan; it has a cosmopolitan distribution [106]. The life cycle of T. gondii involves (i) felines, essentially domestic cats, as definitive hosts in which sexual reproduction occurs, an Life Cycle: The only known definitive hosts for Toxoplasma gondii are members of family Felidae (domestic cats and their relatives). Unsporulated oocysts are shed in the cat's feces . Although oocysts are usually only shed for 1-3 weeks, large numbers may be shed Lytic cycle Figure 1 The Toxoplasma lytic cycle and basic tachyzoite organization. (a) The lytic cycle of invasion, replication, and egress. (b) Organelles in the secretory pathway are shown in white and the secretory organelles themselves in three shades of blue. Abbreviations: EC, endosom

Toxoplasmosis is a zoonotic disease, occurs in almost all warm blooded animals including human beings and is caused by a global protozoan intracellular parasite Toxoplasma gondii Life cycle of toxoplasma gondii pdf As a result of the EU's General Data Protection Regulation (GDPR).We are not permitting internet traffic to Byju's website from countries within European Union at this time.No tracking or performance measurement cookies were served with this page. T. gondii primarily exists in three forms: oocysts, tachyzoites, and bradyzoites

The life-cycle of Toxoplasma gondii reviewed using animations. PMID: 33228743 (view PubMed database entry)DOI: 10.1186/s13071-020-04445-z (read at publisher's website )PMCID: PMC7686686 (free full text version available) Download PDF Toxoplasma gondii is an obligate intracellular parasite capable of infecting a wide variety of mammals and birds. This single-celled protozoan organism might cause a disease known as toxoplasmosis. Cats (Felis catus, domestic cat at GeoChemBio: taxonomy, brief facts, digestive system, development) are primary hosts of Toxoplasma gondii. About. Toxoplasma gondii is a protozoan parasite that infects most species of warm-blooded animals, including humans, and causes the disease toxoplasmosis. Life Cycle The only known definitive hosts for Toxoplasma gondii are members of family Felidae (domestic cats and their relatives) Figure 2 Stages of Toxoplasma gondii. Scale bar in (A) to (D) = 20 μ, in (E) to (G) = 10 μm. (A) Tachyzoites in impression smear of lung. Note crescent-shaped individual tachyzoites (arrows), dividing tachyzoites (arrowheads) compared with size of host red blood cells and leukocytes; Giemsa stain. (B) Tissue cysts in section of muscle Toxoplasma gondii: is an extremely widespread intracellular obligate parasite that infects both animals In the complex life cycle of , sexual development occurs : T. gondii uniquely in felines whereas asexual reproduction may take place in humans and other warm-blooded animals serving as intermediate hosts. The prevalence of infection.

(Pdf) Toxoplasma Gondii: Life Cycle, Pathogenesis, Immune

Search our Collections. The life cycle of Toxoplasma can be divided into two stages; I The asexual cycle with little host specificity i.e., the stage that occurs in sheep, humans, rodents and birds II The sexual stage of the life cycle, confined to the intestinal epithelial cells of cats, which results in the production of oocysts. The asexual life cycle of Toxoplasma The life cycle of Toxoplasma gondii begins when a cat ingests toxoplasma-infected tissue from an intermediate host,usually a rodent. Tissue cysts within the muscle fibers or brain are digested in the cat's digestive tract. The parasite then undergoes sexual development, multiplies in the intestine of.

[PDF] The Life Cycle of Toxoplasma gondii in the Natural

  1. TOXOPLASMA GONDII (Life cycle) Author: dr.majidi Created Date: 10/13/2018 10:02:35 AM.
  2. Toxoplasmosis is a zoonotic disease caused by the protozoal parasite Toxoplasma gondii. Felids are the definitive hosts for T. gondii, but encysted parasites can survive for very long periods, perhaps lifelong, in the tissues of most or all hosts. Transmission and Life Cycle Life cycle There are four major forms of T. gondii: oocysts, which.
  3. Figure 1.1 Life cycle of T. gondii 3 Figure 1.2 Coccidian cycle of T. gondii 6 Figure 1.3 Host cell invasion process of tachyzoites 10 Figure 1.4 Proteomic strategies for protein identification 19 Figure 2.1 Tachyzoite proteins resolved by 1-DE 62 Figure 2.2 A sample of protein identification table of Mascot results 6
  4. Life cycle of toxoplasma gondii. W M Hutchison, J F Dunachie, J C Siim, and K Work. Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (281K), or click on a page image below to browse page by page..
  5. Toxoplasma life cycle pdf Type of protozoan parasite This article is about the parasite. For the disease it causes, see Toxoplasmosis. Toxoplasma gondii Giemsa stained T. gondii tachyzoites, 1000× magnification Scientific classification Clade: SAR Infrakingdom: Alveolata Phylum: Apicomplexa Class: Conoidasida Order
  6. by ES MARTINSEN · Cited by 142 — Parasites were identified to species based on morphology, and a segment of the Toxoplasma gondii, 3 indels were required at base. morphology structure and composition of fruits and vegetables pdf Life Structure, composition, and roles of the Toxoplasma gondii oocyst and sporocyst walls

The Life Cycle of Toxoplasma gondii in the Natural Environment. Authors. Publication date. Publisher 'IntechOpen' Cite. Similar works. Full text. Crossref Provided a free PDF (195.62 KB) This paper was published in Crossref. Having an issue? Is data on this page outdated, violates copyrights or anything else? Report the problem now and we will. The Life Cycle of Toxoplasma gondii in the Natural Environment By Emmanuelle Gilot-Fromont, Maud Lélu, Marie-Laure Dardé, Céline Richomme, Dominique Aubert, Eve Afonso, Aurélien Mercier, Cécile Gotteland and Isabelle Villen The life‑cycle of Toxoplasma gondii reviewed using animations Márcia Attias1,2* , Dirceu E. Teixeira3, Marlene Benchimol4, Rossiane C. Vommaro1, Paulo Henrique Crepaldi1 and Wanderley De Souza1,2 Abstract Toxoplasma gondii is a protozoan parasite that is the causative agent of toxoplasmosis, an infection with high prevalence worldwide View lecture 3 handout.pdf from BIO MISC at University of Massachusetts, Dartmouth. Life cycle of Toxoplasma gondii Openstax, Microbiology, pp. 1148 - 1151 Toxoplasma gondii causes toxoplasmosi Toxoplasma gondii oocysts are resistant to harsh environmental conditions but are rapidly killed when heated to 708 o C. Anatomy of the different life cycle stages of Toxoplasma gondii. Tachyzoites these are the proliferative forms of toxoplasma gondii that reproduce rapidly within macrophages by endogenous budding. Tachyzoites are sickle.

The life-cycle of Toxoplasma gondii reviewed using

  1. T gondii has 2 distinct life cycles. The sexual cycle occurs only in cats, the definitive host. The asexual cycle occurs in other mammals (including humans) and various strains of birds
  2. Toxoplasma gondii strains and production of tachyzoites Two strains of T. gondii (M-7741 and Me-49) originally isolated from sheep diaphragms were used. Strain M-7741 was the same as that used for studying the tissue cyst-induced cycle of T. gondii in cats (Dubey and Frenkel, 1972). The Me-49 strain was the same as that used by Lunde and Jacobs.
  3. The Life Cycle of Toxoplasma gondii in the Natural Environment. NICOLLE C. and L. MANCEAUX. 1909. Sur um protozoaire nouveau du gondii. Paris. 147:763-6. PEYRON, F., A.B. ATEBA, M. WALLON, et al. 2003. Congenital toxoplasmosis in twins: a report of fourteen consecutive cases and a comparison with published data
  4. & Piekarski 1970). Finally the complete life cycle of T. gondii had been characterized defining Toxoplasma as a coccidian parasite with the cat as the definitive host and any warm-blooded animal being able to act as the intermediate host (Fig. 4). The infectious forms in fae-ces were protected in the external environment withi
  5. SYNOPSIS. After reviewing reports of the hosts, structure and life cycle of Toxoplasma, the genus is placed in the apicomplexan family Eimeriidae and the following 7 species are recognized: Toxoplasma gondii (Nicolle & Manceaux) (type species) from about 200 species of mammals and birds, with oocysts in felids; Toxoplasma alencari (Da Costa & Pereira) from the frog Leptodactylus ocellatus.

Toxoplasmosis - Life Cycle - Stanford Universit

Toxoplasma gondii (T. gondii) is the cause of toxoplasmosis, which is a highly neglected disease transmission, life cycle, method of diagnosis, prevention, and control. In 1973, the first case of human toxoplasmosis was reported in Malaysia as reviewed by Yahaya [23]. The review demonstrated a One Health is a collaborative, interdisciplinary effort that seeks optimal health for people, animals, plants, and the environment. Toxoplasmosis, caused by Toxoplasma gondii, is an intracellular protozoan infection distributed worldwide, with a heteroxenous life cycle that practically affects all homeotherms and in which felines act as definitive reservoirs. Herein, we review the natural. Toxoplasma gondii is considered to be one of the most successful parasitic pathogens. It owes this success to its flexibility in responding to signals emanating from the different environments it encounters during its multihost life cycle. The adaptability of this unicellular organism relies on highly coordinated and evolutionarily optimized developmental abilities that allow it to adopt the. Toxoplasma gondii (T. gondii) is considered as one of the most successful parasites in the world. This success is first illustrated by its worldwide distributio The Life Cycle of Toxoplasma gondii in the Natural Environmen

(PDF) TOXOPLASMA GONDII: LIFE CYCLE, PATHOGENESIS, IMMUNEالتوكسوبلازما " Toxoplasmosis " | المرسال

This diagram is a retouched picture, which means that it has been digitally altered from its original version.Modifications: rendering.The original can be viewed here: Toxoplasmosis life cycle en.svg: .Modifications made by Mithril T. gondii can influence the way a host thinks! Infected rodents have been shown to lose their fear of cats and are actually attracted to cat urine.6 This brings them into close contact with felines, increasing the likelihood that they will be eaten and that T. gondii will complete its life cycle within its definitive host Chart and Diagram Slides for PowerPoint - Beautifully designed chart and diagram s for PowerPoint with visually stunning graphics and animation effects. Our new CrystalGraphics Chart and Diagram Slides for PowerPoint is a collection of over 1000 impressively designed data-driven chart and editable diagram s guaranteed to impress any audience Chapter 2.9.10. -- Toxoplasmosis 1286 OIE Terrestrial Manual 2008 disease and Akabane disease. In pigs, Brucella suis (see Chapter 2.8.5) may also cause fetal death, mummification and abortion. • Human health risks Toxoplasma gondii readily infects human beings and while infection is relatively common (approximately 30% of the population depending on age and environment), clinical illness is. The Toxoplasma gondii parasite (belonging to the phylum Apicomplexa) is a common single-celled pathogen that infects around one-third of the human population, where it takes up permanent residence.

The initial attachment of Toxoplasma tachyzoites to target host cells is an important event in the life cycle of the parasite and hence critical in the pathogenesis of this infection. The efficiency of Toxoplasma attachment to synchronized populations of Chinese hamster ovary cells and bovine kidney cells was investigated by using a. Toxoplasma gondii is an intracellular protozoan, and the disease caused by the parasite is a zoonosis called toxoplasmosis. This chapter covers the pathogen epidemiology, parasite development, parasite transmission, the tachyzoite, tissue cyst, and oocyst biology, pathogenesis and clinical features of the disease, immune response, the diagnosis of T. gondii infection, treatment of the disease. Epidemiology of Toxoplasma gondii in Thailand Patcharee Chaichan To cite this version: Patcharee Chaichan. Epidemiology of Toxoplasma gondii in Thailand. Human health and pathology. Figure 4: Life cycle of Toxoplasma gondii..... 19 Figure 5: Southeast Asian countries. File:Toxoplasmosis life cycle it.svg. Size of this PNG preview of this SVG file: 800 × 489 pixels. Other resolutions: 320 × 196 pixels | 640 × 392 pixels | 1,024 × 626 pixels | 1,280 × 783 pixels | 1,177 × 720 pixels

Toxoplasma gondii Life Cycle. The life cycle of Toxoplasma gondii is very complex and comprises two specific phases, sexual and asexual. The sexual part in the life cycle starts after infecting its definitive host, i.e. the cat, while the asexual cycle can take place in any warm-blooded animal Jones JL, Kruszon-Moran D, Sanders-Lewis K, Wilson M. Toxoplasma gondii infection in the United States, 1999 2004, decline from the prior decade. Am J Trop Med Hyg . 2007 Sep. 77(3):405-10. 1. Introduction. The term bradyzoite is classically used to describe a slow-growing life stage of certain organisms belonging to a subclass of apicomplexans known as the Coccidia [].In the case of Toxoplasma gondii, bradyzoites are 7 × 1.5μm crescent-shaped organisms found within intracellular tissue cysts most commonly in neural and muscular tissue []

Toxoplasma Gondii Life Cycle Animation - toxoplasmosis

[PDF] Life cycle of toxoplasma gondii

Toxoplasmosis Caused by Wild Cycle of Toxoplasma gondii, French Guiana Bernard Carme, Magalie Demar, Daniel Ajzenberg, and Marie Laure Dardé From 1998 through 2006, 44 cases of severe primary toxoplasmosis were observed in French Guiana in immuno-competent adults. Toxoplasma gondii isolates exhibited an atypical multilocus genotype Toxoplasma gondii 1. Dr.M.Malathi 2. Obligate intracellular parasite It belongs to coccidian parasites The name toxoplasma derived from toxon arc or bow ( curved shape of the tachyzoites) Phylum - sporozoa 3. Three morphological forms Asexual forms Tachyzoite Bradyzoite (Tissue cyst) Sexual form oocys The effect of digestion in trypsin and acid pepsin on Toxoplasma gondii tachyzoites and bradyzoites was re-evaluated because of recent use of this method to distinguish tachyzoites from bradyzoites. Toxoplasma gondii tachyzoites survived better in 0·5% trypsin solution for 1 h than in 1·0% solution, and occasionally survived for 2 h in acid pepsin solution Life cycle and infection with T gondii. The life cycle of T gondii is quite complex (see figure 1-3) and involves two types of host: definitive host (the cat, including wild cat species and domestic cats), and intermediate hosts (other animals). Figure 1. Figure 2. Figure 3. Definitive host for T gondii Toxoplasmosis is a parasitic disease caused by Toxoplasma gondii, an apicomplexan. Infections with toxoplasmosis usually cause no obvious symptoms in adults. Occasionally, people may have a few weeks or months of mild, flu-like illness such as muscle aches and tender lymph nodes. In a small number of people, eye problems may develop. In those with a weak immune system, severe symptoms such as.


The History and Life Cycle of Toxoplasma gondii 2. The Ultrastructure of Toxoplasma gondii 3. Molecular Epidemiology and Population Structure of Toxoplasma gondii 4. Human Toxoplasma Infection 5. Ocular Disease due to Toxoplasma gondii 6. Toxoplasmosis in Wild and Domestic Animals 7. Toxoplasma Animal Models and Therapeutics 8 Monitoring of dynamin during the Toxoplasma gondii cell cycle In order to achieve this, the best scenario should rely on the synchronized T. gondii invasion of host cells in culture. Then parasites interacted with the host cells for 15 min at 4°C and were transferred to 37 °C for 10 min, after which the samples were fixed and processed for. Determination of nuclear DNA of five Eucoccidian parasites, Isospora (Toxoplasma) gondii, Sarcocystis cruzi, Eimeria tenella, E. acervulina and Plasmodium berghei, with special reference to gamontogenesis and meiosis in I. (T.) gondii - Volume 88 Issue Toxoplasma gondii (/ ˈ t ɒ k s oʊ p l æ z m ə ˈ ɡ ɒ n d i aɪ /) is an obligate intracellular parasitic protozoan eukaryote (specifically an apicomplexan) that causes the infectious disease toxoplasmosis. Found worldwide, T. gondii is capable of infecting virtually all warm-blooded animals,: 1 but felids, such as domestic cats, are the only known definitive hosts in which the parasite.

Toxoplasmosis : life cycle of Toxoplasma gondi

[PDF]T, estimates of infection range from 50 to 80% [].Most infections in humans are asymptomatic but at times the /Schematic-life-cycle-of-Toxoplasma-gondii.png style='max-width:90%' alt=Schematic life cycle of Toxoplasma gondii, and venison), and all other mammals are intermediate hosts.Toxoplasma gondii has three infectious stages: , Using. Books Toxoplasma gondii life cycle (32,704 كتاب). If you do not find what you're looking for, you can use more accurate words. # Forms of Toxoplasma gondii # Series Life Cycle Butterfly life cycle # People gondii # Injury Palmqosh gondii # Gondii # Series Life Cycle Life cycle duck # Uterus Toxoplasma # Uterine vessels Toxoplasma # Kite making Toxoplasma # The life of a commodity cycle. Life cycle of Toxoplasma gondii Toxoplama gondii is a microscopic parasite. Cats are the only recognized de˜nitive host of T. gondii, meaning that this parasite must pass through a cat's digestive system in order to complete its life cycle. eggs (oocysts) shed in cat feces Monk seals may be exposed through ingestion of eggs directly from th

(PDF) Metabolite salvage and restriction during infection

The History and Life Cycle of Toxoplasma gondii

Download and reference Advances In The Life Cycle Of Toxoplasma Gondii by on Citationsy. Download and reference Advances In The Life Cycle Of Toxoplasma Gondii by on Citationsy. Online citations, reference lists, and bibliographies. Do you have existing references in a PDF or Word document Toxoplasma gondii has two life cycles. Sexual cycle happen on cat as definitive host, while asexual cycle happen in other mamalia (include in human) and various bird strain.1,2 This life cycle consist of three forms, tachyzoite and bradyzoite that forming in host mediator and oocyst stage that forming in definitive host epithelial gut cell Download PDF; Order CD-ROM; Order in Print; Home > Medical Reference and Training Manuals > > Figure 2-11. Life cycle of Toxoplasma gondii. - Parasitology II. Figure 2-9. Life cycle of Cryptosporidium species. - Parasitology II: Figure 2-12. Stages of Toxoplasma gondii. - Parasitology II complete their life cycle.25 This attenuation would be immune response against Tgondii, which is ultimately responsible for the course andoutcomeofthe infection.28 located in the anterior halfofthe Toxoplasma, extending from the region of the nucleus through the conoid to the anterior plasmalemma. Theyshow signifi Life Cycle of Toxoplasma gondii: The life cycle of parasite Toxoplasma gondii is different from most other parasites. While other insect life cycles include sexual stages of reproduction, this parasite has asexual and sexual stages of reproduction in felines such as cats. This parasite seems to spread faster amongst intermediate hosts

Toxoplasma Definition, Gondii, Life Cycle, Morphology and Treatment Definition. First discovered in small desert rodents (gundi in Northern Africa) in 1908, Toxoplasma is a genus of the phylum Apicomplexa and consists of a single species known as Toxoplasma gondii Life cycle of Toxoplasma gondii. The life cycle of T. gondii consists of twostages asexual and sexual. The asexual stage takes place in theintermediate hosts, which are mammals or bird. During asexual phase, rapid intracellular growthof the parasite as tachyzoite takes place

Life Cycle: Oocysts take 1-5 days to sporulate in the environment and become infective. Intermediate hosts in nature (including birds and rodents) become infected after ingesting soil, water or plant material contaminated with oocysts . Oocysts transform into tachyzoites shortly after ingestion Toxoplasma gondii infects tissue of the gastrointestinal tract; an active infection is accompanied by fever and enlargement of the spleen. Transmission of Toxoplasma gondii from pregnant women to their fetus can result in severe consequences. REFERENCES 1. Dubey, J.P. 1998. Advances in the life cycle of Toxoplasma gondii. Int. J. Parasitol. 28. oocysts are the most important hosts in the life cycle of T. gondii . Cats become infected with T. gondii by eating infected tissues from intermediate hosts. While foraging on the ground, rodents can get infected by Toxoplasma gondii . Toxoplasmosis is one of the opportunistic infections which in people with immunocompetent is largely asymptomatic

CDC - Toxoplasmosis(PDF) Drug target identification using gene expression

SUMMARY Toxoplasma gondii is an obligate intracellular pathogen within the phylum Apicomplexa. This protozoan parasite is one of the most widespread, with a broad host range including many birds and mammals and a geographic range that is nearly worldwide. While infection of healthy adults is usually relatively mild, serious disease can result in utero or when the host is immunocompromised. Toxoplasma gondii is a protozoan (single-celled) parasite found in muscle and other tissues of many warm-blooded animals including pigs and humans. Cats and other felids are the only hosts in which the parasite can complete its entire life cycle (Figure 1), and the only animals that excrete, in their feces, the environmentally resistant and infec Toxoplasma gondii. Cats are the primary host in the life cycle of the parasite and they can carry the parasite indefinitely without any subsequent health impacts. Other mammals and birds (including Australian marsupials) can become intermediate hosts by eating feed contaminated with T. gondii eggs (she Toxoplasma gondii is an obligate intracellular protozoan parasite, which means that T. gondii is a unicellular eukaryote that survives by living in host cells. T. gondii is in the Apicomplexa family, which includes other protozoans such as Plasmodium species, the causative agents of malaria, and Cryptosporidium , a common cause of childhood. Toxoplasma gondii provides the first comprehensive summary of literature on this organism by leading experts in the field who were responsible for organising the 7th International Congress on Toxoplasmosis in May 2003. It offeres systematic reviews of the biology of this pathogen as well as descriptions of the methods and resources used T. gondii has an entero-epithelial life cycle in its definitive host and is shed in the faeces. This shedding lasts 10-14 days. !There are three major modes of transmission of T. gondii in all host species (including humans and cats): congenital infection, ingestion of infected tissues and ingestion of oocyst-contaminated food or water.