PHLT 304 EXAM 4 Questions & Answers Latest Updated

Infectious disease: Worms and protozoans, Neglected Tropical diseases - Answers April 4 Neglected Tropical Diseases (NTDs) - Answers A number of NTDs are caused by worms and protozoa • NTDs: substantial morbidity & mortality • typically persist only in the poorest, most marginalized communities and conflict areas • Social stigma & disability • Lost income • Children kept out of school • Reduced ability to care for family • All low-income countries are affected by at least 5 NTDs • People in the US are also affected NTD video - Answers - parasitic and bacterial - kills 170,000 a year - 1/7 across 149 - want to 10 NTD by 2020 - use tablets of treatment and are on the brink of elimination - partnerships to help the most poor people CDC's Targeted NTDs - Answers Lymphatic filariasis • Onchocerciasis (oncho or river blindness) • Shistosomiasis (bilharzia, snail fever) • Soil transmitted helminths • Trachoma • Guinea worm disease (Dracunculiasis) Helminths (Parasitic Worms) - Answers adult Ascaris Lumbriocoides worm they can range from 15 to 35 cm NTD: Lymphatic Filariasis (LF) - Answers Infection caused by a parasitic worm, transmitted by mosquitoes • Over 1 billion people are at risk in 81 countries • Over 120 million are already infected • Can cause permanent disability including swollen limbs, genital damage, or swollen limbs with thickened, hardened skin (elephantiasis) • Individuals with severe symptoms are often disabled & may suffer severe social stigma and rejection by communities NTD: Onchocerciasis (River blindness) - Answers World's 4th leading cause of blindness • Infection caused by worm transmitted by blackflies • 120 million people at risk • 37 million people currently infected, almost all in Africa Symptoms: • Intense itching • Disfiguring skin lesions • Eye disease that can cause blindness NTD: Schistosomiasis (Schisto, Bilharzia, Snail Fever) - Answers Caused by parasitic worms (genus Schistosoma) in fresh water • Infection through skin contact with the water • 700 million people in 74 countries are at risk • 240 million are already infected • Second only to malaria as the most common parasitic disease Symptoms include: • blood in urine or stool • Anemia • problems with growth and development in children • Bladder cancer • Kidney, liver problems • Most deadly NTD; kills approx. 280,000 individuals/yr only in Africa NTD: Guinea worm disease ("Dracunculiasis") - Answers • caused by drinking untreated, unfiltered water containing the parasite Dracunculus medinensis • affects some parts of Africa • No effective drug treatment & no vaccine • Symptoms develop about 1 yr after exposure; include fever, rash, nausea, vomiting, diarrhea, dizziness • Painful blister develop & larvae are released from blister that can re- infest water • Complications from open wound: redness, swelling, generalized infection, joint infections that can cause the joints to lock & deform, tetanus • If worm breaks during removal, can cause intense inflammation, swelling & pain • Low death rate but often disabling, particularly during worm removal & recovery • Both a disease of poverty and a cause of poverty Guinea worm disease eradication efforts video - Answers - only method was to pull out worm day by day - Jimmy Carter eradication effort - 3.5 mil cases reduced by 99.9% - need to break worm life cycle - public edu., supply water filter, and water treatment NTD: Soil-transmitted Helminths (STHs) - Answers Acquired through contact with soil contaminated with infected feces • Previously common globally including in the US • > 4 billion people are at high risk globally • > 1 billion individuals already infected Infection can contribute to: • Anemia • Vitamin A deficiency • Malnutrition and impaired growth • Delayed development • Intestinal blockages Soil-transmitted Helminths (STHs): whip worm (Trichuris trchiura) - Answers Illness caused by ingestion of eggs • Produces colitis • Can cause dysentery • Over 600 million people affected (likely 1 billion) NTD: Round Worms- Ascaris lumbricoides - Answers "round worm" • Common in tropical or warm and moist climates • Eggs and larvae carried in feces - soil and foods • Caused by ingesting eggs • Often no symptoms • Can cause abdominal pain, intestinal blockage, and impair growth • Worms can migrate through body to lungs and cause coughing • DALYs range from 30-150 per 100, 000 people • WHO reports consider this "intolerable DALY loss" NTD: Helminths - Necator americanus - Answers "hookworm" • can penetrate the skin of humans • Itching and localized rash • Can cause fatigue, abdominal pain, diarrhea, loss of appetite, weight loss, anemia • Severe infections can impact the cognitive and physical growth • "hookworm" • Over 570 million people affected • Contributes to (22 million annually) DALYs and global burden of disease Protozoans - Answers Microscopic, one-celled organisms • Can be free-living or parasitic Four groups based on type of movement: • Amoebas, e.g., Entamoeba • Flagellates, e.g., Leishmania • Ciliates, e.g., Balantidium • Organisms whose adult stage is not motile, e.g., Plasmodium NTD: Chagas Disease - Answers Also called American trypanosomiasis • Caused by the protozoan parasite Trypanosoma cruzi • Infection often acquired through contact with the feces of an infected triatomine bug (or "kissing bug") that often lives in poor housing conditions • Can have mother-to-baby transmission • Mexico, Central America, and South America: an estimated 8 million people are infected • Approx. 300,000 people in US infected; mostly infected in endemic countries NTD: Chagas Disease pt. 2 - Answers Acute phase of disease: occurs immediately and can last up to a few months • May cause fever or swelling around site of inoculation; occasionally causes severe inflammation of heart muscle or brain and lining around brain • Next, prolonged asymptomatic phase with few/no parasites in blood An estimated 20-30% of infected individuals develop debilitating, potentially severe effects: • Heart rhythm abnormalities that can be fatal • Other cardiac alterations • Dilated esophagus or colon, causing functional problems with eating/elimination NTD: Leishmaniasis - Answers • Found in every continent except Australia & Antarctica • Human infections are caused by more than 20 species of parasites of the genus Leishmania • Transmitted by the bite of sand flies (about 30 species of phlebotomine sand flies) • Sand fly vectors are most active dusk to dawn • Cutaneous leishmaniasis: approx. 700,000 - 1.2 million cases/yr globally • Usually heals without treatment but can take months or years • Visceral leishmaniasis: previously ~ 400,000 cases/yr, now may be < 100,000 cases/yr globally • Severe cases are usually fatal Leishmaniasis: Prevention - Answers • No drugs or vaccines can prevent infections • Avoid sand fly bites • Sand flies are much smaller than mosquitoes and can pass through smaller holes NTDs: what else is being done? - Answers • World Health Organization • Government agencies in affected countries • US Agency for International Development • Corporations such as Johnson & Johnson • Bill & Melinda Gates Foundation International NGOs, e.g. • Carter Center: Guinea Worm Eradication Program • Doctors without Borders Johnson & Johnson Video - Answers - 1 bil suffer from NTD - Johnson & Johnson joined public and private partners to eliminate/ control disease 10 by 2020 - medication with intestinal worms - 200 mil doses a year - school age children vulnerable - flubendozal, active to 3 NTD Malaria - Answers • Not an NTD • Mosquito-borne disease caused by 4 species of the protozoan parasite Plasmodium; the most severe form is caused by P. falciparum • Transmitted by the female Anopheles mosquitoes (bite dusk to dawn) Malaria Video - Answers - 198 Million cases worldwide - fever with headache 1-4 weeks after bite from mosquito - plasmodium parasite - from hot and humid seasons - over 3 bil are at risk - most cases in death in subsaharan Africa - early diagnosis is important - before treatment you must test - best treatment: artemisinin- based combo therapy (ACT) - prevention: WHO recommends insecticide infested bed nets - children under 5 and pregnant women are most vulnerable - antimalarial medicines - sulfadoxine for women - research working on malaria vaccine - is preventable and curable Malaria: WHO Global Technical Strategy - 3 Pillars - Answers 1) Ensure universal access to malaria prevention, diagnosis and treatment 2) Accelerate efforts towards elimination and attainment of malaria-free status 3) Transform malaria surveillance into a core intervention Prevention & Treatments - Answers - sleeping under bed nets - indoor residual spraying with insecticide - Quick treatment for rapid & complete elimination of Plasmodium parasite from patient's blood - Travelers: prevent mosquito bites & take antimalarial medicine Toxoplasmosis - Answers • Caused by protozoan parasite Toxoplasma gondii • Infects most species of warm- blooded animals, including humans • Risk - infant, immune compromised, pregnant • Important cause of death from foodborne illness • Transmission: • Undercooked contaminated meat • Food or water contaminated by cat feces • Contact with contaminated soil • Blood transfusion • Transplacentally from mother to fetus • One of the TORCHH infections we discussed in the maternal/child health lecture Key waterborne protozoan pathogens - Answers Cryptosporidium • contaminated water; causes diarrhea, tolerant to chlorination; problem in USA Giardia lamblia • global problem; from contaminated food or water; tolerant to chlorine disinfection Naegleria fowleri • causes primary amoebic meningoencephalitis (PAM), a disease of the central nervous system • Rare; almost always fatal SARS- Covid-19: - Answers has not been detected in municipal drinking water; should be removed/ inactivated by routine drinking water treatment Bacterial disease, Case study: tuberculosis (4/9) Viral diseases - Answers April 14 Beneficial bacteria - Answers According to Dr. E. Quigley, chief of the Division of Gastroenterology and Hepatology, Houston Methodist Hospital, the gut microbiota is the "forgotten organ" that plays a critical role in health and disease Beneficial gut microbiome - Answers • At birth: the entire intestinal tract is sterile • Infant gut is colonized by maternal and environmental bacteria during birth and through feeding & other contacts • By age 2.5 years, the microbiota is similar to that of an adult, with a variety of bacterial species • composition of the flora is influenced by age, diet, socioeconomic conditions • Antibiotics have the potential to profoundly impact the microbiota • Microbiota help protect the host from colonization by pathogenic species Pathogenic Bacteria - Answers Ways of categorizing bacteria - Answers Effect on humans: • Most don't cause disease in humans • Beneficial bacteria: microbiome in the body can help prevent growth of other more dangerous bacteria • Pathogens: cause disease Effect of oxygen: • Aerobic bacteria need oxygen • Anaerobic bacteria have trouble living/growing in the presence of oxygen • Facultative bacteria can live/grow with or without oxygen Staining, e.g., Gram staining: • The differences in staining are due to differences in cell wall • Gram-positive & Gram-negative bacteria cause different types of infections and are treated with different types of antibiotics • Gram-positive: stain blue/purple • Gram-negative: stain red/pink Shape: • spheres (cocci) • rods (bacilli) • spirals or helixes (spirochetes) Pertussis (whooping cough) - Answers • Caused by the bacterium Bordetella pertussis • The bacteria attach to the cilia (tiny, hair-like extensions) that line part of the upper respiratory system and release toxins that damage the cilia and cause airways to swell • Highly contagious, spread by coughing or sneezing • Babies are highly susceptible • Older individuals may not realize they have the disease • DTaP vaccine • Worldwide, an estimated 24.1 million cases and about 160,700 deaths per year Cholera - Answers • Gram-negative bacterium Vibrio cholerae • profuse watery diarrhea, vomiting, and leg cramps • Rapid loss of body fluids leads to dehydration and shock. Without treatment, death can occur within hours Managing a cholera outbreak after a natural disaster video - Answers CDC Response to Haiti - decrease death in health facilities and communities - increasing oral rehydration solution distribution points throughout the country so communities remain healthier when they experience cholera - monitor spread of epidemic - epi and lab science - diarrheal disease. lose one liter of water an hour - 2 day training course to send professionals to provide care - ORS sachets Typhoid - Answers • You can get typhoid if Salmonella typhi bacteria from sewage gets into the water you use for drinking or washing food • Still common in the developing world • Approx. 26 million cases each year • Estimated 7,500 cases/year in the US, mostly acquired during international travel • Causes low-grade septicemia, can be severe or life-threatening • Vaccines only ~ 50-80% effective Meningococcal meningitis - Answers • There are multiple types of meningitis • Meningitis caused by the bacterium Neisseria meningitidis is called meningococcal meningitis • Spreads faster in dorms and barracks • Can lead to meningococcal septicemia - blood infection, damages walls of blood vessels, causing bleeding into skin and organs • 10 university outbreaks in US Staphylococcus aureus - Answers • Health care-associated infections • Community associated infections - often due to skin-to-skin contact Staph infections can lead to: • Bacteremia or sepsis • Pneumonia • Endocarditis (infection of the heart valves), which can lead to heart failure or stroke • Osteomyelitis (bone infection) due to bacteria in bloodstream or due to trauma or IV drug abuse