Glossary of BICD 136 MT 1
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- Exists when a significant segment of a population is infected with a particular infectious organism at the same time
- exists when all or most of the worlds populations experience epidemics of the same organism at the same time.
- infected people either become immune
(and cease to produce infectious agents), or they die.
- acute infection
- susceptible people become infected and may survive with no or subclinical symptoms, but they do not become immune. Rather they continue to be infected and to produce infectious agents. They may eventually show overt symptoms and die from the disease, but
- chronic disease
- the course of the epidemic is a function of the rates of these interconversions
- the immigration rate, the birth rate, the infection rate, the immune rate and the
- The infection rate is an amalgam of two separate rates
- the encounter rate (the rate at
which susceptible people are exposed to the agent by infected people) and the efficiency of transmission
- In 165 AD the population of Rome was about 54 million. By 542, following a succession of three epidemics (smallpox, then measles, then plague), the population fell to:
- between 10 and 20 million. Shortly thereafter Rome fell to the Visigoths, and the European Dark Ages ensued.
- Plague is caused by a bacterium called
- Yersinia pestis
- In 1664 the plague killed
- 70,000 (15% of the population) in London
- In 1894 the plague took
- 80,000 to 100,000 lives in Hong Kong and Canton, from where it spread by ship to the western US
- Until then, the foremost theory among physicians and other educated people was that health and illness, and also personality, were determined by the balance of four bodily "humors." The humors were
- yellow bile, black bile, blood and phlegm
- excess of yellow bile was supposed to make a person
- irritable, easily angered and cynical, and we still use the word "choleric" to describe such a person
- An excess of black bile made a person
- "melancholic," and we still use the word for a sad, depressed, wistful, pessimistic person
- An excess of blood made one
- one energetic and optimistic, and we call these people "sanguine,"
- "phlegmatic" people are
- slow to react, lazy, speaking little
- In 1840s, germ theory was revitalized by
- German physician, Henle (b/c of improvements to microscopes)
- The established a set of criteria for implicating a particular organism as causing a given disease. These criteria have become known as Koch’s Postulates. They are:
- 1) The organism must always be present in diseased individuals
2) It must be possible to isolate the organism from diseased individuals and grow it in pure culture
3) The cultured organism must cause the disease when introduced into a susceptible host
4) It must be possible to re-isolate the organism from the newly infected host.
- Limitations of Koch's postulates in human disease
- These, particularly #3 and #4, are difficult to apply strictly to human diseases, for ethical reasons. Also #2 is impossible to apply to viral diseases, since viruses cannot be grown in pure culture. They can only be grown in cultures of host cells.
- are people who look for signs of the beginnings of what might become
epidemics, and when they see such signs go to work to uncover the nature of the organism involved, the mode of transmission, etc, so that they can decide how best to stop the inci
- John Snow and the London (SoHo) cholera epidemic of
- John Snow tracked the outbreak by:
- by labeling areas of London where deaths had occured and found them clustered. He then located a water pump that was carrying the bacteria and was used by the places infected and stopped the epidemic.
- Fracatorio - Italian monk proposed
- germ theory - disease caused by "germs" that are alive and have the ability to reproduce and spread - dismissed because can't see them
- The HIV epidemic in the US officially began on and with what?
- 6/5/81, with the publication in the
Morbidity and Mortality Weekly Report (MMWR) of the Centers for Disease Control and Prevention of a report by Dr. Michael Gottlieb of UCLA of 5 cases of Pneumocystis carinii pneumonia (PCP), all in young, white, sexually active homosexual men with no history of or apparent reason for immune deficiency. 2 of the 5 were dead by the time the report was published.
- The issue of the MMWR cited a report of 26 young homosexual men, 25 white and 1 black, with Kaposi’s sarcoma (KS) came out on what date?
- 7/3/81. The report also mentioned that 10 of these 26 also had P. carinii pneumonia
- P. carinii infections in heterosexual IV drug users in New York
- a case of heterosexual transmission (This was big news because the epidemic in Africa had not been discovered yet. HIV transmission is by heterosexual contact in the vast majority of cases in Africa and worldwide.)
- implication that blood products were spreading the disease, particularly hepatitis B vaccine. Hemophiliacs receiving factor VIII and individuals receiving transfusions were also
being diagnosed with AIDS.
- AIDS was reported to have occurred in 16 countries, and in 1,000 US cases (in 34 states) of which 500 were already dead. Also, a California mother was reported to have acquired AIDS from sexual contact with her hemophiliac husband, and then passed it to their child. This was the first reported case of vertical transmission.
- Philadelphia, in 1793, had an epidemic of
- yellow fever (June/July)
- Blank are vectors of yellow fever
- The symptoms of yellow fever include
- high fever, hemorrhages, internal bleeding and black vomit, and yellowish skin and eyes
- Who saw several affected patients, and gave notice that an epidemic was underway?
- Benjamin Rush
- Who was resistant to yellow fever and hired to work at the hospital?
- African Americans
- What ended the epidemic?
- Winter - November weather killed the mosquitos and halted the outbreak.
- What did people do with infected people?
- Put them outside to die because of the fear of contracting the disease from infected family members
- What were the Stonewall riots?
- On 6/27/1969 New York police raided a gay bar called the Stonewall, a part of a routine and officially sanctioned pattern of harassment of such establishments. When they began to handcuff patrons and load them into police wagons rioting broke out and went on for two days. This marked the beginning of the struggle for gay liberation and of an ongoing process of attitude change on the part of society in general. June 27 is celebrated as Gay Freedom Day in many places around the world.
- Gay Related Immune Deficiency
- When was it changed to AIDS?
- 9/82: MMWR stated as Aquired Immune Deficiency Syndrome
- Michael Gottlieb first showed that the immune deficiency his patients were experiencing was characterized by
- a severe reduction in the number of T cells in the circulation. The specific type of T cell that is depleted is variously called the T4 cell, CD4+ T cell or T helper cell. T4 cell counts are still used as an index of the severity of immune compromise and disease progression.
- What are acute symptoms?
- The symptoms that develop within a few days after infection with a disease
organism. Only lasts a few days.
Many people infected with HIV report not experiencing any acute symptoms, but some report a short bout of flu-like symptoms, including sore throat, swollen lymph nodes, and fatigue.
- How long does the asymptomatic period? What influences its varience?
- 1 to 10 years - How long this phase
lasts depends in part on the constitution of the patient, but viral variation plays a role as well. Within the past year or two an HIV strain was reported that appeared to progress from infection to AIDS in a matter of a few months. Seroconversion occurs during the asymptomatic period, usually by 6 months after infection, but nearly always by 1 year.
- What is seroconversion?
- that the person’s serum begins to contain detectable levels of anti-
HIV antibodies, indicating that an immune response to HIV is underway.
- What is ARC and when does it occur?
- The asymptomatic period is followed by the onset of initial symptoms (ARC, or AIDS Related Complex), and then by the development of “full-blown AIDS.” Initial symptoms often involve significant weight loss, often accompanied by diarrhea, and night sweats. Persistent swelling of the lymph nodes is likely to occur.
- What are some conditions that HIV causes directly?
- AIDS Dementia Complex, for example, is a condition caused directly by the HIV virus. Those with ADC have HIV-infected cells in the brain. (Neurons are among the cell types HIV can infect.) Early symptoms of AIDS Dementia include apathy, loss of interest in one's surroundings and the like. Later symptoms involve cognitive and motor problems. Memory loss, as well as mobility problems, may happen as well. Peripheral neuropathy is another, related, condition directly attributable to HIV. In this case infection is of the peripheral nerves rather than the brain. The most common symptom is severe, burning, aching pain in the feet and legs, which may prevent walking. This syndrome is a result of the degeneration of the nerves responsible for conducting impulses to the extremities. It generally occurs with more severe immunosuppression and is steadily progressive.
- What qualifies as full-blown AIDS?
- When the count of T4 helper cells falls to less than 200 per microliter, the patient is vulnerable to infection by normally harmless organisms, leading to “opportunistic infections (OIs).” Normal healthy individuals usually have T cells counts around 1000 per microliter, although occasional transient circumstances can cause counts temporarily to drop as low as 300.
- What are the fungal infections?
- Candida albicans (thrush - treat with fluconazol or amphotericin B)
Pneumocystis carinii pneumonia - treat with pentamidine or Bactrim
Cryptococcus neoformans - meningitis - Fluconazol
Histoplasma capsulatum - eyes
Coccidioides immitis - any organs
Aspergillus - soil - swelling of face
- What are the protozoan infections?
- Cryptosporidium parvum - intestine - diarrhea - immodium
Toxoplasma gondii - animals - brain - sulfadiazine
- What are the bacterial infections?
- salmonella and shigella - frequent food poisoning
Staphylococcus and Pseudomonas - pneumonia and sinusitis
Rochalimaea - bacillary angromatosis (blood problems) - antibiotics
Mycobacteria: M. avium - MAC - azithromycin and M. tuberculosis - most common killer - isoniazid
- What are the viral infections?
- CMV - cytomegalovirus - retinitis - gancyclovir
HPV - human papilloma virus - skin and mucus, warts and cancer
JCV - most have, but causes Progressive Multifocal Leukoencephilitis - loss of muscles - no treatment
Varicella zoster -chicken pox virus - shingles - acyclovir
Epstein Barr - non-Hodgins lymphoma or primary lymphoma of the brain - chemo; or hairy lymphoma
Herpes - Kaposi Sarcoma HV - mostly men
- What adds to the susceptible pools?
- Birth and immigration rates
- What does vaccination influence?
- What are three outcomes of viral infections in the body?
- Disease (shorten time when can be successful if kills host), nothing (successful), or benefit (successful - can live in harmony and pass on genes)
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