SPHU 1020- Cell, Individual, and Community. Cropley Midterm Review
SPHU 1020- Cell, Individual, and Community. Cropley Midterm Review SPHU 1020
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This 11 page Study Guide was uploaded by Claire Jacob on Saturday February 20, 2016. The Study Guide belongs to SPHU 1020 at Tulane University taught by Dickey-Cropley, Lorelei in Summer 2015. Since its upload, it has received 193 views. For similar materials see Cell, Individual & The Community in Public Health at Tulane University.
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Date Created: 02/20/16
Midterm Study Guide Examples of microbes, characteristics of microbes What makes a microbe? ● Microbe is a term of convenience ● microscopic size and unicellularity are not absolute characteristics of microbes like fungi (some bacteria are macroscopic). Examples of microbes ● Bacteria AKA “germs” ○ morphology: ■ bacillus ■ coccus ■ spiralis ○ features: ■ Capsule not integral to cell ■ Cell wagram positive vs. gram nega ive) ■ Outer membrane (in gram negatives only) ■ Plasma membrane, selectively permeable ■ Cytoplasm ■ Appendages ● flagella like tails ● pili flagella that cover the surface of the bacteria ○ binary fission for reproduction (asexual) ○ the first lifeforms on Earth ○ cause illness, also useful to make vitamins, break down some types of garbage, and maintain our atmosphere ○ have a cell wall ○ biochemically diverse ○ found in every environmental niche ○ only about 2% of all bacterial species have been identified ● Viruses ○ infect all cell types ○ viral envelopes used for attachment ○ Unable to do much of anything on their own, viruses go into host cells to reproduce, often wreaking havoc and causing disease. Their ability to move genetic information from one cell to another makes them useful for cloning DNA and could provide a way to deliver gene therapy ○ cause disease by destroying the host cell ○ need electron microscope to see them because they are so small ○ essentially, viruses can be harvested for good, not just harm ● Fungi (yeast, mold) ○ from a singlecelled yeast to a 3.5milewide mushroom, fungi do everything from helping to bake bread to recycling to decomposing waste ○ harmful to people with insufficient immune systems (HIV/AIDS) ● Algae/ Protozoa ○ Plantlike algae produce much of the oxygen we breathe; animallike protozoa (including the famous amoeba) help maintain the balance of microbial life ○ includes: algae, slime molds ○ some algae create toxins that hurt marine life… then when these fish eat the algae, it’s a part of their bodies and then humans consume it and you can become sick from the neurotoxins ● Helminths (worms) ● Prions… Mad Cow Disease is one ○ infectious protein particles ○ acellular ○ lack RNA and DNA ○ reproduce from a protein that’s found in the brain *All of these can be pathogenic except algae (although they can produce toxins) Concepts of disease transmission including role of fomites, vectors, reservoirs, sources, vertical transmission, Portals of entry and portals of exit... ● Fomites: inanimate objects that serve as means of transmission of infectious material (doorknobs, toilet seats, kitchen sponges, etc.) ● Vectors: biologic vs. mechanical transmission ○ biologic: the vector (in most cases, an insect) is infected with the microbe ○ mechanical: the vector is not infected, but serves as transport for the microbe ● Source: immediate site from which pathogen transferred to host. ● Reservoir: site in nature in which microbes survive (& possibly multiply) & from which they may be transmitted ○ Some organisms able to survive and multiply in nonliving environments, such as soil and water ● Vertical transmission: a method of transmission characterized by passage of pathogens from parent to offspring across the placenta, in breast milk, or in the birth canal ● Portals of entry and ex: ○ pathogens leave host through portals of exit ○ many portals of exit are same as portals of entry ○ pathogens often leave hosts in materials body secretes/ excretes Concepts of immune system including Pathogen, Antigen, Herd immunity, role of T cells, B cells ● Pathogen: microbes capable of producing disease ○ Pathogenicity: ability to cause disease; proportion of infected persons who develop clinical disease ○ Why do pathogens cause disease and some don’t?Virulenc ● some infectious agents are easily transmitted (very contagious), but they are not very likely to cause disease (not very virulent) ○ ex: polio virus: probably infects most people who contact it, but only about 510% of those infected actually develop disease ● other infectious agents are very virulent, but not terribly contagious ○ ex: ebola hemorrhagic fever virus virulence very high (5090% fatality rate among those infected); however, virus not transmitted easily by casual contact ● most worrisome infectious agents are those that are both very contagious and very virulent ● Antigen: component of microbes, usually protein structures, that are recognized as foreign by the immune system and are targeted for destruction ○ Antibodies or immunoglobulins, recognize & bind to specific ontigens (this is considered an adaptive response) ● Herd immunity: immunity of enough members of a population to protect against an epidemic… especially important for those who have suppressed immune systems and are not able to receive immunization ● T cells and B cel : ○ Humoral (antibodymediated) immunity ■ Triggers production of antibodies specific for an antigen ■ Antibodies only produced by activated B lymphocytes ■ Helper T cells (TH) critical in activating B lymphocytes Here are some crash course videos made by John Green’s brother (yes, the guy who writes all of the sappy novels your girlfriends talk about)... he’s a little odd, but still really helpful!!! https://www.youtube.com/watch?v=GIJK3dwCWCw Table of Contents Physical Barriers Like Skin and Mucous Membranes2:01 Phagocytes: Neutrophils and Macrophages 3:17 Natural Killer Ce4:29 Inflammatory Response 5:29 https://www.youtube.com/watch?v=2DFN4IBZ3rI Table of Contents Adaptive Immune System's Humoral Response 1:19 How B Cells Mature, Identify Antigens, and Make Antibodies 2:42 How Antibodies Warm Pathogens and Mark Them for Death 5:22 Active and Passive Humoral Immunity6:03 How Vaccines Work 6:27 https://www.youtube.com/watch?v=rd2cf5hValM Table of Contents Helper, Cytotoxic and Regulatory T Cells Attack Compromised Body Cells 4:08 Cytokines Activate B and T Cells :00 When Your Immune System Goes Rogue 6:15 Autoimmune Trouble 7:27 Vaccines recommended for routine use by U.S. CDC and the World Health Organization Specific characteristics , such as transmission cycle, of Schistosomiasis, leishmaniasis, Lymphatic filariasis, guinea worm Schistosomiasis : ● >200 million people infected; prevalence increasing ● widely distributed throughout Africa, S america and some parts of Asia; distribution increasing with migration ● Epidemiology and risk factors ○ source of infections: humans and mammals (esp. cattle) ○ Route of transmission: transmission occurs in freshwater where larval stage of schistoma come in contact with and penetrates human skin ○ 3 factors: ■ method of disposal of human excreta ■ presence of snail intermediate host ■ contact (via swimming, bathing, etc) ● s/s: ○ acute: early systemic circulation of schistosomules fever, enlargement and tenderness of liver, dysentery ■ itchiness develops at the penetration site ■ fever, chills, cough, and muscle aches ○ late stage: eggs trapped in tissues or embolizing to liver ■ damage caused to the liver, intestine, or bladder ■ more rarely, eggs may move to the brain or spinal cord, causing seizures, paralysis, or inflammation of the spinal cord ■ can also damage the spleen, liver, lungs, intestine, and bladder, causing the abdomen to become distended ● prevention: treat patients and domestic animal at the same time ○ avoid infected water ● Life cycl ○ live in snails which release immature, freeswimming, microscopic forms, called cercariae ○ exposure to water containing cercariae allows penetration into the skin ○ migrate into blood vessels and enter into the liver ■ the adults coat themselves with antigens of the host to avoid detection by the host’s immune system ○ a male and female pair migrate into small blood venules (veins) of the intestinal tract or bladder ○ the worms feed on blood ○ eggs are discharged by defecation or urination into the water ○ the eggs hatch, penetrate the snails, and develop into cercariae Leishmaniasis: ● caused by flagellated protozoan Leishmania ○ endemic in most tropical and subtropical areas ○ transmission: by bite of female sandflies ○ they are phagocytosed and differentiate and multiply within host macrophages ○ Life cycle: ■ when an infected sand fly bites a human, the parasites enter the skin and are engulfed by cells called macrophages (biological transmission) ■ the parasites multiply and are released when a microphage bursts ○ 3 human manifestations; ■ determined by parasite species, geographic location, and host immune response ■ Visceral leishmaniasis(aka kalaazar) ● the most severe form with close to a 100% mortality rate ● parasites invade the liver and spleen and cause characteristic symptoms, including irregular bouts of fever, weakness, weight loss, anemia, and protrusion of the abdomen due to the swelling of the spleen and liver ■ Mucocutaneous leishmaniasis (aka espundia) ● parasites invade the skin and mucous membranes, causing destruction of the nose, mouth, and throat ■ Cutaneous leishmaniasis (aka Baghdad boil and tropical boil) ● results in mild disfiguring skin lesions, primarily on exposed parts of the body, particularly the face, arms, and legs ○ prevention ■ interruption of transmission by reducing vector Sandfly population ■ prevent sandfly bites: ● PPM: Personal Protective Measures: insecticide treated nets (DEET) Lymphatic Filariasis: “elephantiasis” ● Primary causative agent Filarial nematode: Wucheraria bancrof ● 250 million humans affected; widely spread in tropical and subtropical countries ● route of transmission ○ transmitted to humans by mosquitos ○ transmission depends on 2 issues: ■ availability of vectors ■ presence of a population of people to infect the vector ○ called Biological Transmission because part of its life cycle is completed whilst in the mosquito ● clinical disease ○ early s/s: fever ○ later: elephantiasis (common, but incorrect word: elephantitis) ○ late complication of filariasis ○ lymphangitis (enlargement of limbs, scrotum, breasts, or vulva with dermal hypertrophy and verrucous changes ○ lymphadenitis (femoral, inguinal, auxiliary nodes) ● DX, TX, Prevention and Control ○ DX: made on clinical grounds ■ using blood films ■ use of sentinel sites ○ TX/ prevention: ■ antiinflammatory agents ■ diethylcarbamazine (DEC), antihelminthic drugs: ivermectine, albendizole, doxycycline ● Life cycle: ○ initiated by the bite of mosquitos carrying filarial larvae ○ larvae migrate into the lymphatic vessels where, within about a year, they grow into adult worms with a lifespan of up to several years ○ the adult worms mate and the female release into the blood millions of microfilariae that may be ingested by mosquitoes taking a blood meal Guinea Worm Dracunculiasis: guinea worm ● found in African communities lacking clean drinking water ● transmission: ingest water containing larvaeinfected copepods ○ ingested larvae penetrate stomach and intestinal wall and enter abdominal cavity where they mature into adult worms ○ migrate to foot or leg, blister forms, and then burrow out of the foot ● Life cycle: ○ Life cycle: ■ drinking water contaminated with dracunculus larvae→ small copepods (“water fleas”) feed on these larvae. Copepods are small crustaceans in the phylum Arthropoda. ■ when someone ingests water containing infected copepods, the copepods are digested but not the worm larvae, which penetrate the stomach and intestinal wall and enter the abdominal cavity ■ after appx 1 year, females migrate toward the skin surface, most commonly the foot or leg. A painful blister that eventually ruptures occurs at the site. ● people sometimes immerse the blistered area in water in an attempt to relieve pain. the temp change causes the blister to open, exposing the adult worm. these worms are very skinny though, and in an induced event such as this, only part of the worm will escape and the rest will remain in the leg, leading to bacterial infection ● after the natural rupture of the blister, the onemeterlong worm begins to enzymatically bore its way out through the skin→ causes excruciating and debilitating pain Guinea worm eradication? ● prevention based on teaching villagers to filter copepods from their drinking water ● Guinea worm disease set to become 2nd human disease in history, after smallpox, to be eradicated, 1st parasite disease to be eradicated and 1st disease to be eradicated without use of a vaccine or medicine ● 3.5 million cases in 1986 to 126 in 2014, this year, 22 incidences ● Main initiative of Carter Center and Bill and Melinda Gates Foundation working with CDC, WHO, etc. Exit tix questions… I’m really sorry but I don’t have a clue how to access these Guest speaker slides … and we haven’t had a guest speaker yet so woohoo! Make sure that you also review your own notes and the slides from class! While I’ve filled out the midterm review found on blackboard to the best of my ability, I can’t guarantee that everything on the test is going to be in this document. Good luck and happy studying!
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