EESA10 Lecture 7.docx

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Environmental Science
Silvija Stefanovic

EESA10 Lecture 7– Feb 29, 2012 Transmissible diseases - No one single factor is responsible for transmissible diseases. - We can know the agent (bacteria, virus, etc.) - We sometimes wrongly believe that transmissible diseases are a thing of the past, or care confined only to third world countries. - More quickly transmitted now, because of increased travel. In the olden days, takes years to go from one continent to another, these days it can spread much more quickly. - Antibiotics: o Antibiotics can cure bacterial diseases, but not viral diseases. The latter requires other types of medication. o Many bacteria are become resistant to known antibiotics. Why? Because sometimes we consume antibiotics even if we don’t need it/aren’t prescribed it. For example, we take antibiotics for a viral disease. o We get antibiotics through meat – some animals are fed antibiotics to boost their immune system so that they won’t get sick. Animals get fed antibiotics even when they are not sick, as prevention. o Microbes reproduce very quickly, so they can mutate very quickly and can become resistant in a short period of time (many generations of microbes in an hour). Tuberculosis - We’ve known about tuberculosis for a LONG time. - In the middle ages, it was associated with vampires because one of the symptoms was coughing out blood. - An illness of the “poor and hungry”. Poor housing, not enough vitamins, quality of food, not enough sleep/rest. - Transfer: from person to person, coughing, sneezing, etc. Can be transferred to healthy person. Mostly through lungs, because it is breathed in. - Can be in body without causing systoms for many years, until the immune system of person drops at which time person would exhibit acute symptoms – loss of appetite, fatigue… - Medications:  Antibiotics.  There are many types of tuberculosis now, and so medication that was effective in the 60s and 70s is not effective now.  Can be controlled by vaccination. In most countries, children get a dose after birth and another dose later on. Vaccines are not available in some countries/areas. Should get vaccinated before travelling to risky zone. Anthrax - Doesn’t transmit person to person, but animal to person. - Spore forming bacteria. - Cannot determine if a person will experience sickness just by knowing number of spores that person has been exposed to. However, higher number of spores increases risk that the illness will occur. - Three major forms:  Cutaneous – skin  Inhalation  Gastrointestinal – through food or drink. - Spores have no smell or taste. - Can be used as bioweapon. - Cutaneous  Incubation period – one to twelve days (from time of infection to first signs of symptoms).  Most common naturally occurring type. - Inhalation  Worst type  Most likely to be used as bioweapon  Very large range of incubation period (1-60 days)  Prognosis – 75% of cases result in death. - Gastrointestinal  Improperly cooked or raw contaminated meat. - Bioterrorism – Spores mixed with powder, a material to transport/carry spores.  Powder  Oily stain on envelop.  Reduce exposure as much as possible (number of people exposed, area). Leave package where found, leave room and turn off ventilation system because spores can travel through ventilation.  Specialists will take swipes from areas and may take nasal swipes of people who might have been exposed.  Doesn’t really tell if those individuals will get sick (because we don’t know what number of spores will cause illness) but it will tell us if the person was actually exposed or if it was a false alarm.  Vaccine – recommended for people who deal with wool or meat on a daily basis without of origin of the material (where is it coming from, is it safe or not) or if someone travels to area where anthrax is common. Plague - Pneumonic Plague  Can exist by itself or be a result of bubonic - Bubonic Plague  Cycle must be present – fleas and rodents must be there. Person has been bitten by a flea that has fed on the blood of an infected rodent. The flea will transfer bacteria into human bloodstream.  Does not spread from person to person. - Septicemic Plague  When plague multiplies in blood  Can occur by itself, or as a result of pneumonic or bubonic. Yellow Fever - Viral disease - Came to America with European pioneers. - Mosquitoes are necessary. - Tropical areas are the best for mosquitoes. Many of these areas have yellow fever as endemic d
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