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Lecture 8

HLTB21 - November 7- Lecture 8 .docx

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Department
Health Studies
Course
HLTB21H3
Professor
R Song
Semester
Fall

Description
November 7, 2013- Lecture 8 Many of the diseases have been around, but haven’t diagnosed them in humans- they’ve existed in animals mostly The Third Epidemiological Transition  Persistence of Chronic Non-Infectious Diseases,  Newly Emergent & Re-Emergent Infectious Disease Infectious diseases notable for 1) many new diseases causing mortality being detected; 2) increased incidence and prevalence of previously controlled (re-emergent) infectious diseases; 3) many re-emergent pathogens evolving into drug-resistant strains The interaction of:
 1) Socialchange
 2) Demographicchange 3) Environmentalchange 4) Microbialadaptation 5) Medicalmalpractice CDC: Emerging infectious diseases are those infections that appeared recently in a population, or those that already existed but are spreading rapidly, in terms of both incidence and geographical distribution (Grisotti and Avila-Pires 2010) Institute of Medicine (IOM), 1992: “new, re-emerging or drug-resistant infections whose incidence has increased in the last two decades, or whose incidence threatens to increase” (Cohen 2000) Third transition: very fluid Issue of shift from second transition Second transition starts turn of the century Post WW2 Important factor in decreasing infectious disease Burden of disease: In terms of persistence of infectious disease: we have to attribute HIV/AIDS as a significance factor -> it affects millions of people -> diminishes immune system Immuno-compromised bodies: our immune system has changed We are aging population: we’re living longer. -> hence we have inseparable chronic diseases; in the past we didn’t live long enough to suffer from those kinds of disease, like heart failure, etc. It can be emergent in one location and be somewhere else in another location Issues in recognition. 1. Recent introduction of a new etiological agent (or its recognition) 2. Mutation arising in an existing agent Followed by its rapid dissemination in the population  Grmek (1993) substituted the idea of emergence for that of novelty and proposed five distinct historical instances for the recognition of emergence and novelty. 1.It existed before being recognized, but escaped medical attention because it went unrecognized as a nosological entity of its own. 2.It existed, but was only detected after a qualitative and quantitative alteration of its characteristics made it noticeable (pathogen evolution). 3.It was introduced in a region where it did not occur previously, i.e., due to war, migration, population movements 4.The emergence of a disease acquired from a non-human reservoir (zoonoses). 5.A new disease emerges and spreads, when the causal agent or the necessary environmental conditions for its occurrence did not exist before the first clinical observations identified its presence; also possibly as a result of laboratory manipulation of pathogenic organisms intended for research, biological warfare, or genetic engineering of agricultural products (Grisotti and Avila-Pires 2010) 6. In addition to the categories proposed by the CDC and by Grmek, Grisotti and Avila-Pires (2010) add the role of under-notification of those conditions presented by official lists of diseases subjected to compulsory notification, and also the failure to recognize and notify uncommon diseases. “Under-notification is at the basis of many emergent diseases. These cases occur and are diagnosed, but doctors and health authorities ignore or fail to report them.” 3. 16 century: considered newly emerging, but they were actually brought there. 4. First restricted to animals, but not affecting humans 5. new form of anthrax 6. New emerging meaning newly recognized by medical professionals  Newly emergent disease: Crutezfeld Jakob Disease (human form of Mad Cow)  Today we can’t think of infectious and chronic disease. A lot of the infectious ones might lead to chronic.  Bacterial infections can lead to ulcers. Confusion with syphilis:: confused with leprosy.  so when it appeared, confused with a new disease. Newly emerging diseases: Toxic Shock Syndrome: first clinically recognized in 70s and 80s- bacterial infection infecting women, those who used tampons, because it led to blood infections and led to shock, hence they died. MRSA: streptococcus orios -> this form is anti-biotic resistance. It’s new in the sense because we haven’t had this type of infection prior to 10-15 years. Food-Borne Disease  Food safety can be compromised at many levels today, esp. due to massive scale of food production - especially animals (though note, beginning of 20 th century was more challenging due to various factors...) • Emergence of non-typhoid salmonellosis, campylo bacteriosis, listeriosis, and infections involving E. coli O157:H7, Cyclospora, calicivirus and Vibrio vulnificus • Estimated that food-borne illness accounts for 76 million illnesses, 325,000 periods in hospital and 5,000 deaths in the United States annually (Mead et al. 1999)  Sterosis related to food products.  This will increasingly become a problem. We are a larger population so more food production period, hence there’s more chances for contamination and microorganisms to enter the supply. The animal food production: more animals being produced and we’re used to eating more meat rather than vegetables. They’re carrying drug-resistance bacteria with them.  Culture of eating out is a main source of why we see food-born infectious disease Resistance to antimicrobial drug.  A lot of infections that are acquired in hospital settings are become drug- resistant. This is because of misuse and overuse of antibiotics. There’s a lot of fake drugs out there.  Hospital-acquired infections: nosocomial infections -> source of newly evolved forms of disease related to drug-resistance  Randomly prescribing drugs to something that’s not even an infection.  Hospital and community-level infections  Developed and developing nations  1970s: drug-resistant N.gonorrheae and Haemophilus influenzae were recognized worldwide  Drug-resistant bacteria: Shigella dysenteriae  Food-borne pathogens such as salmonellae, Campylobacter 
due to overuse of antimicrobials in food animals  Between 1979-1994, frequency of multiple drug resistance in 
Salmonella increased from 17% to 31% (Lee et al. 1994)  Between 1991 and 1999, ciprofloxacin resistance in 
Campylobacter increased from 0% to 13.6% (CDC 1999) Constructing “Emergence” Grmek 1993: 6. In addition to the categories proposed by the CDC and by Grmek, Grisotti and Avila-Pires (2010) add the role of under-notification of those conditions presented by official lists of diseases subjected to compulsory notification, and also the failure to recognize and notify uncommon diseases. “Under-notification is at the basis of many emergent diseases. These cases occur and are diagnosed, but doctors and health authorities ignore or fail to report them.” Abdominal Angiostrongyliasis  Infection by nematode from Angiostrongylus genus of kidney and alimentary tract roundworms  Symptoms vague, though can include abdominal pain, nausea, vomiting, weakness, which can progress to fever, then central nervous system impairment (cognitive, slowed reaction, headache)  Commonly asymptomatic  No cure  Usually only diagnosed by viewing and 
isolating parasite through biopsies or detecting it through serological tests  Newly emergent or under-diagnosed?  Endemic in Costa Rica, emergent in Brazil Chagas Disease  Parasitic infection of protozoan Trypanosoma cruzi; commonly transmitted by insect vector, blood- sucking “kissing bugs” / assassin bug  Symptoms (but not always): fever, anemia, swelling of lymphatic
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