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Protozoa - Wikipedia, the free encyclopedia

3 Classification. 3.1 Sub-groups. 4 Human disease; 5 References ... However, both protozoa and protists are paraphyletic groups (not including all genetic ...

Infectious disease

An infectious disease is a clinically evident illness resulting from the presence of pathogenicbiological agents, including pathogenic viruses, pathogenic bacteria, fungi, protozoa, multicellular parasites, and aberrant proteins known as prions. These pathogens are able to cause disease in animals and/or plants. Infectious pathologies are also called communicable diseases or transmissible diseases due to their potential of transmission from one person or species to another by a replicating agent (as opposed to a toxin).

Transmission of an infectious disease can occur through one or more of diverse pathways including physical contact with infected individuals. These infecting agents may also be transmitted through liquids, food, body fluids, contaminated objects, airborne inhalation, or through vector-borne spread. Transmissible diseases which occur through contact with an ill person or their secretions, or objects touched by them, are especially infective, and are sometimes referred to as contagious diseases. Infectious (communicable) diseases which usually require a more specialized route of infection, such as vector transmission, blood or needle transmission, or sexual transmission, are usually not regarded as contagious, and thus are not as amenable to medical quarantine of victims.

The term infectivitydescribes the ability of an organism to enter, survive and multiply in the host, while the infectiousness of a disease indicates the comparative ease with which the disease is transmitted to other hosts. Aninfection however, is not synonymous with an infectious disease, as an infection may not cause important clinical symptoms or impair host function.


Among the almost infinite varieties of microorganisms, relatively few cause disease in otherwise healthy individuals. Infectious disease results from the interplay between those few pathogens and the defenses of the hosts they infect. The appearance and severity of disease resulting from any pathogen depends upon the ability of that pathogen to damage the host as well as the ability of the host to resist the pathogen. Infectious microorganisms, or microbes, are therefore classified as either primary pathogens or as opportunistic pathogens according to the status of host defenses.

Primary pathogens cause disease as a result of their presence or activity within the normal, healthy host, and their intrinsic virulence (the severity of the disease they cause) is, in part, a necessary consequence of their need to reproduce and spread. Many of the most common primary pathogens of humans only infect humans, however many serious diseases are caused by organisms acquired from the environment or which infect non-human hosts.

Organisms which cause an infectious disease in a host with depressed resistance are classified as opportunistic pathogens. Opportunistic disease may be caused by microbes that are ordinarily in contact with the host, such as pathogenic bacteria or fungi in the gastrointestinal or the upper respiratory tract, and they may also result from (otherwise innocuous) microbes acquired from other hosts (as in Clostridium difficilecolitis) or from the environment as a result of traumatic introduction (as in surgical wound infections or compound fractures). An opportunistic disease requires impairment of host defenses, which may occur as a result of genetic defects (such as Chronic granulomatous disease), exposure to antimicrobial drugs or immunosuppressive chemicals (as might occur following poisoning or cancerchemotherapy), exposure to ionizing radiation, or as a result of an infectious disease with immunosuppressive activity (such as with measles, malaria or HIV disease). Primary pathogens may also cause more severe disease in a host with depressed resistance than would normally occur in an immunosufficient host.

One way of proving that a given disease is "infectious", is to satisfy Koch's postulates (first proposed by Robert Koch), which demands that the infectious agent be identified only in patients and not in healthy controls, and that patients who contract the agent also develop the disease. These postulates were first used in the discovery that Mycobacteria species cause tuberculosis. Koch's postulates cannot be met ethically for many human diseases because they require experimental infection of a healthy individual with a pathogen produced as a pure culture. Often, even diseases that are quite clearly infectious do not meet the infectious criteria. For example, Treponema pallidum, the causativespirochete of syphilis, cannot be

From Yahoo Answers

Question:i need 3 from each and 1. causal agent or vector 2. organ affected 3.symptoms.

Answers:--Bacteria Disease 1: Lyme Disease Causal Agent: Borrelia burgdorferi Vector: Deer Tick Organs Affected: early = skin rash, late = nervous system/brain Symptoms: bullseye rash, etc http://en.wikipedia.org/wiki/Lyme_disease#Symptoms Disease 2: Pulmonary/Inhalation Anthrax Causal Agent: Bacillus anthracis Organs Affected: Lungs, lymph nodes Symptoms: cold or flu-like symptoms for several days, followed by severe (and often fatal) respiratory collapse Disease 3: Legionaires Disease Causal Agent: Legionella pneumophila Organs: lungs Symptoms: Initial symptoms are flu-like, including fever, chills, and dry cough. Advanced stages of the disease cause problems with the gastrointestinal tract and the nervous system and lead to diarrhea and nausea. --Viruses Disease 1: AIDS Causal Agent: HIV Organs: T-cells (not an organ) Symptoms: Low T-cell count & many opportunistic infections http://en.wikipedia.org/wiki/AIDS#Symptoms Disease 2: Chicken Pox Causal Agent: Varicella Zoster Virus Organs: upper respiratory tract, lymph nodes, liver, spleen, epidermis Symptoms: Red bumpy rash over entire body, enlarged spleen & liver Disease 3: Hepatitis Causal Agent: Hepatitis A-G virus Organs: liver Symptoms: More specific symptoms, which can be present in acute hepatitis from any cause, are: profound loss of appetite, aversion to smoking among smokers, dark urine, yellowing of the eyes and skin (i.e., jaundice) and abdominal discomfort. --Fungi Disease: Athletes foot Causal Agent:Trichophyton rubrum and T. mentagrophytes. Organs: skin Symptoms: Athlete's foot causes scaling, flaking and itching of the affected skin. Disease: Ringworm Causal Agent:Tinea corporis Organs: skin Symptoms:the enlarging raised red rings with a central area of healing Disease: allergic bronchopulmonary aspergillosis Causal Agent: Aspergillus spp. Organs: lungs Symptoms: poorly controlled asthma, with wheezing, cough, shortness of breath and exercise intolerance. --Protists Disease: Malaria Causal Agent: Plasmodium spp. Organs: blood, liver Symptoms: fever, shivering, arthralgia (joint pain), vomiting, anemia (caused by hemolysis), hemoglobinuria, and convulsions. Disease: Toxoplasmosis Causal Agent: Toxoplasma gondii Organs: blood, brain (rarely) Symptoms: swollen lymph nodes, or muscle aches and pains that last for a month or more. Disease: Leishmaniasis Causal Agent: Leishmania spp. Organs: skin, blo0d Symptoms:he symptoms of leishmaniasis are skin sores which erupt weeks to months after the person affected is bitten by sand flies. Other consequences, which can become manifest anywhere from a few months to years after infection, include fever, damage to the spleen and liver, and anaemia.

Question:Also, "describe the life cycle of Plasmodium, the sporozoan that causes malaria. What features typical of sporozoans does this life cycle exhibit?" For the second question, I did describe the life cycle, but I don't know the second part about "what features typical of sporozoans..." Thanks in advance!

Answers:chlorine and other purification methods with water

Question:I'm supposed to do a powerpoint presentation on Infectious canine hepatitis. It says that it is caused by canine adenovirus type 1 (CAV-1). would that be the disease causing agent? some sources on the internet, though, say that it is the same thing as infectious canine disease. can anyone tell me anything about that?

Answers:it's a virus that is specifically to dog family/wolf/. not transmitted to people, There are diseases that humans and animals can share. Look up zoonotic diseases. Disease causing agents are viruses, bacteria, flies etc. Diseases have different names for same condition. Read more about infectious canine disease or call a vet for more info..

Question:Each group of protozoans (ciliates, amoebas, flagellates, and sporozoans) has parasitic species. Use the Internet and books to find at least one disease that affects humans and is caused by a member of each group. Please show me a link based on this assignment

Answers:I knew this one on the top of my head :Trichomoniasis Here are more: http://www.microbiologyprocedure.com/eukaryotes-microbes/list-of-protozoan-diseases-in-human.htm Hope this helped.

From Youtube

How Bacteria Cause Disease :Join Warren Levinson to learn about the various agents that cause infectious diseases: bacteria, viruses, fungi, protozoa and worms, with a focus on how bacteria are transmitted and cause disease, and how exotoxins and endotoxins cause symptoms of disease. Series: "UCSF Mini Medical School for the Public" [2/2007] [Health and Medicine] [Show ID: 12104]

Alzheimer's Disease Caused by Infection :Images of Borrelia DNA in Alzheimer's Disease brain tissue- Including Specific DNA probes for Borrelia Flagellin DNA ( A DNA sequence which is NOT present in the human genome) which glows Green when it finds its Target DNA in Alzheimer's brain tissue. Also illustrated in this short video are the concepts of TRANSSYNAPTIC transmission of infection in Rabies,and in Herpes Zoster/Shingles. Infections INSIDE of a nerve cell are transmitted Across Synapse connections to neighboring Nerve cells. Borrelia spirochetes gain access to the interior regions of nerve cells and are also\ capable of "JUMPING' across Synapses to infect neighboring Nerve cells. Networks of Connected nerve cells (NEURAL CIRCUITS) then become infected by Trans-synaptic transmission. This "NETWORK" of infected nerve cells in the brain explains the PATTERN of Sequential destruction of Brain tissue in the Braak Stages of Alzheimer's Disease through the Braak stages I,II,III, IV, V , VI. For more information please visit the Molecular Alzheimer website at www.molecularalzheimer.org