Environmental Health Past Paper - ENV221H1F 2024 - PDF

Environmental Health ENV221H1F – November 28, 2024 1  Volunteer Note-takers Accessibility Services needs dependable volunteer note-takers to assist students living with a disability to achieve academic success! Volunteers report that by giving to th...

Environmental Health ENV221H1F – November 28, 2024 1  Volunteer Note-takers Accessibility Services needs dependable volunteer note-takers to assist students living with a disability to achieve academic success! Volunteers report that by giving to the U of T community their class attendance and note taking skills improve. All you have to do is attend classes regularly & submit your notes consistently: 1. Register Online as a Volunteer Note-Taker at: https://clockwork.studentlife.utoronto.ca/custom/misc/home.aspx 2. Click on Volunteer Notetakers, and sign in using your UTORid 3. Select classes you wish to be a volunteer for 4. Start uploading your notes right away Email us at [email protected] if you have questions or require any assistance. Volunteers may receive co-curricular credit and/or a certificate of appreciation.  Announcements Environmental Health Essay (20%) – due Dec 1st How to implement Canadians’ rights to a healthy environment? Final Exam – 35% - cumulative, but with 20/80 split between 1st & 2nd term. Wed Dec 11th, 7-9pm A – PH – BN322 PO – ZZ – ES 1050 – NOTE – cannot enter exam room without proper photo ID 4  Environmental Health Infectious Diseases Infectious Diseases – re-emerging & emerging health threat – Re-emerging TB, malaria – Emerging SARs, West Nile, Zika, Novel/Swine flu, COVID-19, bird flu 5 RE-EMERGING INFECTIOUS DISEASES 6  Malaria life-threatening disease found typically in tropical countries. infection is caused by a parasite and does not spread from person to person. transmission is relationship between: Plasmodium spp. parasitic protozoan Human Anopheles mosquito 7  8 http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ijid/vol4n2/plasmodium.xml  Malaria was endemic in the US until the 1950s but was considered eliminated by 1951 – HOW? annually ~2000-2500 malaria cases in US linked to travel to malaria endemic areas (sub-Saharan Africa, S. America, SE Asia) in 2023 US recorded first homegrown malaria cases in decades (Florida, Texas, Maryland) – HOW? Anopheles mosquitoes capable of carrying malaria are present in the U.S. – but few opportunities to transmit the parasite because there are so few infected people to feed on. 9  Malaria Malaria is caused by a parasitic protozoa (Plasmodium sp.) that is transmitted between humans by mosquitoes Wide-spread use of DDT and apparently effective malaria control by way of mosquito control lead to the abandonment of other malarial control programs and the disease was neglected for several decades When DDT was banned (mosquitoes had developed resistance to it in any event), malaria re-emerged Re-emergence was followed relatively quickly by Plasmodium resistance to the only two antimalarial drugs available at the time (chloroquine and mefloquine) There are more cases of malaria today than 40 years ago Malaria now kills over 600,000-1 million people a year, and an estimated 300- 500 million are infected with the protozoan parasites that cause malaria 10 Malaria associated mortalities have risen quickly with the emergence of drug resistance in the parasite 11  12 https://www.npr.org/sections/goatsandsoda/2019/03/28/707604928/chart-where-disease-carrying-mosquitoes-will-go-in-the-future 13  Two malaria vaccines are currently recommended for use in children living in moderate to high malaria transmission areas. Current malaria vaccines reduce uncomplicated malaria by ~40%, severe malaria by ~30%, and all- cause mortality by 13%. 14 https://www.cdc.gov/malaria/php/public-health-strategy/malaria-vaccines.html Why did it take so long to develop a malaria vaccine? 15  Prevention is best approach to slowing spread Screens on homes and mosquito nets for beds, biological control, altering marsh areas, zinc & vitamin A supplements to boost resistance in children, insecticides Despite a ban on DDT, special dispensation to allow 25 countries to continue using DDT for malaria control until other alternatives are available 16 EMERGING INFECTIOUS DISEASES 17 Meganck, R. & R.S. Baric. 2021. Developing therapeutic approaches for twenty-first century emerging infectious viral diseases. Nature Medicine. 27: 401-410. 18 SARS The Cough Heard Around the World - 2003 Severe acute respiratory syndrome SARS coronavirus (SARS – CoV) First recognized as global threat in March 2003 Believed to be an animal virus that crossed the species barrier to humans Natural reservoir suspected to be Himalayan masked civet, Chinese ferret badger and the raccoon dog By July 2003, 8098 SARS cases in 26 countries with 19 774 deaths  SARS –vulnerability revealed Spread from person to person. Required no vector. Incubated silently for over a week. Mimicked symptoms of other diseases. Killed about 10% of those infected. Spread easily along international air travel routes -2 billion passengers/year. Spread in city hospitals. Damaged economies, societies, politics and the international image of countries. 20 Probable SARS transmission on flight CA112 in March 2003 21 Meganck, R. & R.S. Baric. 2021. Developing therapeutic approaches for twenty-first century emerging infectious viral diseases. Nature Medicine. 27: 401-410. 22  Middle East respiratory syndrome coronavirus (MERS-CoV) a viral respiratory disease caused by Middle East respiratory syndrome coronavirus (MERS-CoV) that was first identified in Saudi Arabia in 2012. Coronaviruses are a large family of viruses that can cause diseases ranging from the common cold to Severe acute respiratory syndrome (SARS) and Coronavirus disease-2019 (COVID-19). Typical MERS symptoms include fever, cough and shortness of breath. Pneumonia is common, but MERS patients may not always develop this condition. Gastrointestinal symptoms, including diarrhoea, have also been reported among MERS patients. Approximately 35% of MERS cases reported to WHO have died. MERS-CoV is a zoonotic virus, meaning it is transmitted between animals and people. MERS-CoV has been identified and linked to human infections in dromedary camels in several Member States in the Middle East, Africa and South Asia. Human-to-human transmission is possible and has occurred predominantly among close contacts and in health care settings. Outside the health care setting, there has been limited human-to-human transmission. 23  Transmission MERS-CoV is a zoonotic virus with humans infected through direct or indirect contact with infected dromedary camels. Human-to-human transmission is possible and has occurred predominantly among close contacts and in health care settings. Outbreaks in Saudi Arabia, UAE, Korea No sustained human-to-human transmission documented anywhere in the world outside of health care settings. From April 2012 to date, a total of 2613 laboratory-confirmed cases of Middle East respiratory syndrome (MERS) were reported globally, with 943 associated deaths at a case-fatality ratio (CFR) of 36%. The majority of these cases were reported from Saudi Arabia, with 2204 cases and 862 related deaths (CFR: 39%). 24  West Nile Virus Mosquito-borne illness with mild flu-like symptoms, but some (1/150 infected) can develop permanent neurological issues first identified in Uganda in 1937, but has since spread to many other parts of the world High of >5,500 cases in US in 2012 to 2016 annual average of ~2,000. (CDC) 25 26  27 https://www.publichealthontario.ca/en/eRepository/Vector-Borne_Diseases_Summary_Report_2016.pdf https://www.publichealthontario.ca/en/Data-and-Analysis/Infectious- Disease/West-Nile-Virus 28 29 Zika Virus first discovered in a monkey in the Zika Forest of Uganda in 1947 since then, outbreaks of Zika have been reported in tropical Africa, Southeast Asia, and the Pacific Islands related to the dengue, yellow fever, Japanese encephalitis, and West Nile viruses Outbreak in 2015-2016 impacted 2016 summer Olympic Games, mostly impacted the Americas Worldwide: estimates of ~700,000 infected with 18 deaths 30 Source: US CDC 31  What is Zika? Virus spread primarily through the bite of an infected Aedes aegypti or Aedes albopictus mosquito. Many people infected with Zika virus won’t have symptoms or will only have mild symptoms. Zika virus infection during pregnancy can cause microcephaly and other severe brain defects.  In most cases, there are no symptoms. In a few cases, Zika can trigger paralysis (Guillain-Barré Syndrome). In pregnant women, it may cause subsequent birth defects. There's no vaccine or specific treatment for the disease. Treatment instead focuses on relieving symptoms and includes rest, rehydration and medications for fever and pain. 33  Epidemic vs. Pandemic (WHO definition) Epidemic: occurs when there are more cases of that disease than normal Pandemic: worldwide epidemic of a disease – emergence of a disease new to a population; – agents infect humans, causing serious illness; and – agents spread easily and sustainably among humans. 34  Annual Influenza estimated to affect 5–15% of the global population. cause severe illness in 3–5 million people and 250,000–500,000 deaths worldwide. Current subtypes of influenza A commonly found in people are influenza A (H1N1) and influenza A (H3N2) viruses 35  Influenza A Virus Types divided into subtypes based on two proteins on the surface of the virus: the hemagglutinin (H) and the neuraminidase (N) 16 different hemagglutinin subtypes 9 different neuraminidase subtypes. E.g. H5N1, H1N1, H3N2 Source: medicineworld.org 36  20th Century Flu Pandemics Spanish Flu – 1918-1919, Influenza A, H1N1 – 1/3 or ~500 million people were infected globally, with 50-100 million deaths Swine Flu – 2009-2010, A(H1N1)pdm09 – 11-21% infected globally (700 mill – 1.4 bill of 6.8 bill) with 284,000 deaths Current annual flu typically impacts 5-15% (340mill – 1 billion) with 250,000-500,000 deaths 37  Novel (Swine) A/H1N1 – April 2009 Current subtypes of influenza A commonly found in people are influenza A (H1N1) and influenza A (H3N2) viruses In the spring of 2009, a new influenza A (H1N1) virus emerged Novel H1N1 was very different from regular human influenza A (H1N1) viruses It is an unusual cocktail of avian, swine and human strains of influenza A virus 38 39  illness is generally mild, except in some cases for people in higher risk groups differs in its tendency to affect younger, healthier people Individuals exposed to flu prior to 1957 are thought to have some immunity Pandemic declared over in Aug 2010 40  Spanish Flu flu pandemic of 1918-1919 infected ~ 500mill (1/3 of world’s population) killed 20-50million, including 675,000 Americans first observed in Europe and quickly spread globally within months did not originate in Spain, but Spain was hit hard and not under wartime news blackouts like other affected European countries 1st wave in Spring of 2018, 2nd more highly contagious wave in fall 2018, 3rd wave winter 2019, with victims dying within hours or days of developing symptoms: skin turning blue and lungs filling with fluid that caused them to suffocate citizens ordered to wear masks, schools and businesses closed, advised to avoid shaking hands & stay indoors 41 COVID 19 SARS-CoV-2 beta coronavirus family of viruses that can cause mild to moderate upper respiratory tract illnesses origins in bats detected in China in Dec 2019, likely originated in a “wet market” in Wuhan, China transmission when infected person coughs or sneezes through expelled droplets contact routes: mouth, eyes, nose, droplets can also be inhaled into the lungs 42  3 Routes of Exposure 1. droplets 2. fomites 3. Aerosols 43  44 https://data.who.int/dashboards/covid19/cases?n=c 45 46 Disease Infection Microbe People Infected Deaths Period Globally Spanish Flu 1918-1919 A/H1N1 33% (500mill) 50-100 million Annual Flu Annually A/H3N2, A/H1N1 5-15% (340mill – 1 250,000-500,000 billion) Novel H1N1 (swine 2009-2010 Novel A/H1N1 11-21% (700mill – 1.4 ~284,000 flu) billion) of 6.8 billion SARS 2003 SARS-CoV 8,098 774 COVID 19 2019-?? SARS-CoV-2 776,841,264 (~10%) 7,075,468 47  Pathogens to Watch Out For in the Future COVID-19 Crimean-Cong haemorrhagic fever Ebola virus Marburg virus Lassa fever Middle East respiratory syndrome (MERS) Severe Acute Respiratory Syndrome (SARS) Nipah and henipaviral diseases Rift Valley fever Zika Disease X 48 Avian/Bird Flu & Migration Corridors Routes 49 50 51  Ways to Prevent Infectious Disease Increase research Reduce poverty & malnutrition while improving drinking water quality Reduce unnecessary use of antibiotics, both in humans & livestock Use all of antibiotic prescription Careful handwashing Immunize children Oral hydration for diarrhea Reduce HIV/AIDS 52  Fig. 1. Mapping of long-term research areas in relation to future risks of pandemics D. Destoumieux-Garz´on et al. 2022. Getting out of crises: Environmental, social-ecological and evolutionary research is needed to avoid future risks of 53 pandemicsEnvironment International 158 (2022) 106915