Hepatitis A virus, Shigella species, Salmonella speciesĮ. Influenza viruses, SARS, Klebsiella species, S. epidermisĪirborne droplets from sneezing or coughing Hepatitis B and C HIV/AIDS, Staphylococcus aureus, S. Human Reservoirs and Transmission of Infectious Agentsīlood, needle stick, other contaminated equipment The following table summarizes the human reservoirs and methods of transmission of common infectious agents. Humans are the most common reservoirs of pathogens that can infect themselves (see E. Inanimate reservoirs include soil, water, food, feces, intravenous fluid and equipment. ReservoirsĪ reservoir is any person, animal, arthropod, plant, soil or substance (or combination of these) in which an infectious agent normally lives and multiplies, on which it depends primarily for survival, and where it reproduces itself in such manner that it can be transmitted to a susceptible host.Īnimate reservoirs include people, insects, birds, and other animals. They infect humans principally through ingestion of fertilized eggs or when the larvae penetrate the skin or mucous membranes. Helminths include roundworms, tapeworms, and flukes. ![]() Infestation occurs by direct contact with the arthropod or its eggs. Arthropods include scabies (mites), lice, and fleas, which generally infest skin, causing inflammation and itching. Protozoa are single-celled organisms transmitted via direct or indirect contact or an arthropod vector (an infected carrier). Protozoa, arthropods and helminths are all parasites. Parasites are organisms that infect and cause disease in animals. Giardia stick closely to the lining of the small intestine in the hosts they infect and cause mild to severe diarrhea. Protozoa parasites: giardia trophozoites in a variety of positions. However, fungi such as Pneumocystis carinii can be life-threatening to the person with HIV/AIDS. ![]() Other viruses, such as the influenza and SARS viruses, quickly announce their presence through characteristic symptoms.įungal infections are prevalent throughout the world but only a few cause disease in humans, and most commonly affect the skin, nails, and subcutaneous tissue. Viruses such as HIV/AIDS, and Hepatitis B and C have the ability to enter and survive in the body for years before symptoms of disease occur. Viruses are intracellular parasites that is, they can only reproduce inside a living cell. In contrast, the tuberculosis bacillus infects only a small number of people, usually people with weakened immune function, or those who are undernourished and living in crowded conditions. For example, the smallpox virus is particularly virulent, infecting almost all people exposed. The virulence of these pathogens depends on their number, their potency, their ability to enter and survive in the body, and the susceptibility of the host. ![]() Pathogens include not only bacteria but also viruses, fungi, and parasites. Teaching patients this simple technique can help prevent urinary tract infections in the future.īacillus can refer to any rod-shaped bacterium, or can be more specific to Bacillus, which is a gram-positive and rod-shaped genus. A simple way for a woman ( susceptible host) to break the chain of infection is to wipe from front to back. However, when E.coli ( infectious agent) exits the gastrointestinal tract ( reservoir) through the anus ( portal of exit), it can spread to the urinary tract by indirect contact ( mode of transmission in women-wiping from back to front) and cause a urinary tract infection (UTI). For example, the large intestine is colonized with Escherichia coli. The presence of bacteria in and on the human body is normal these bacteria are called resident flora. The reservoir (the normal location of the pathogen).Infection control measures are designed to break the links and thereby keep the infection from spreading.
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