Bios30401 Lecture 22 PDF

Arthropod transmitted diseases II (Protozoan, Helminth) Soil and Water borne diseases Bios30401 Dec 9,2024 Leishmaniasis (a.k.a. Kala azar) Leishmania protozoa Causes skin lesions (cutaneous) or can invade whole body (visceral disease-fatal) Carried by sand flies...

Arthropod transmitted diseases II (Protozoan, Helminth) Soil and Water borne diseases Bios30401 Dec 9,2024 Leishmaniasis (a.k.a. Kala azar) Leishmania protozoa Causes skin lesions (cutaneous) or can invade whole body (visceral disease-fatal) Carried by sand flies (biological vector) Becoming common to see in soldiers from Iraq (Baghdad Boil) Drugs available but side effects African sleeping sickness Trypanosome T brucei Tsetse fly Several hundred thousand cases/yr in sub Saharan Africa Death within 2 years (untreated) Drugs are toxic and resistance develops Chagas disease Trypanosome T. cruzi Reduviid bug vector (kissing bug) Central and South America-16-18 million cases, 50,000 deaths/yr Initial disease often mild but 20 ys later chronic disease fatal. Heart problems Drugs most effective during initial infection Chagas disease and autoimmunity Chronic stage of Chagas Little or no detection of parasite Lesions on the heart Heart transplant only cure T. cruzi and heart muscle antigenically similar Autoimmune disease? Helminths carried by arthropods Lymphatic filariasis (Elephantiasis) 40 million worldwide “the poorest of the poor” Haiti program Legs extremely swollen with lymph 10 times more often in scrotum-up to 1 in 4 men (hydrocoel) Lymphatic filariasis-Etiology Parasitic worms (threadlike nematodes) Larvae (microfilariae) enter host by bite of mosquito (multiple infections necessary for disease) Larvae mature and mate in bloodstream Migrate to lymph nodes-within months can be several inches long and block drainage Females produce new larvae that enter bloodstream to be picked up by new mosquito (nighttime in Haiti)  Life cycle Endemic in 55 countries 1 billion people threatened  Lymphatic filariasis-treatment and prevention Once elephantiasis occurs can not be reversed. Male hydrocoel can be surgically repaired Prevention of secondary infections Various anti-worm drugs (like heartworm drugs for dogs) for adult worms. Yearly large doses - Mectizan (adult female worms live and reproduce for about 6 years) Noble prize in 2015! Larva easier to kill-prevent manifestations Haiti eradication program-drugs in salt (diethylcarbamazine citrate (DEC) ) Bed nets http:// www.cartercenter.org/video/Default.aspx?youtube_id= pw7TSYLRrmQ&category=Health&filter=Lymphatic% 20Filariasis  Worms transmitted by arthropods (cont.) Loaisis Loaisis Loa loa worm transmitted by deer flies African rainforest Adult worms live in eyes-microfilaria in blood during day Does not cause blindness River blindness Roundworm-microfilaria- transmitted by blackflies Africa and Central America Worms invade eye and blood vessels become fibrous Almost all over 40 blind – first infected when young Treatments now available – if caught before blindness https://www.cartercenter.org/health/river_bli ndness/index.html Soil borne diseases-Fungi Yeast Single cell Molds Mycelia Only about 50 species cause human disease Important pathogens of plants  Fungal diseases Hypersensitivity (allergy) Mycotoxins Some release dangerous toxins Mycoses Infections on or in the body Major problem for immunocompromised FYI Fungal skin disease Candidiasis (Candida albicans) Thrush Vaginitis Nails Madura foot (soil organisms including fungi) Other fungal infections Athlete’s foot Fungal infection of the eye Ringworm Fungal diseases-treatment Fungi are eukaryotes Many treatments topical to limit toxicity Fungi have unique sterol-ergesterol-azoles target Some drugs target fungal cell wall and chitin FYI  Bacterial soil borne Tetanus 500 cases since 1997 in U.S.- 75 deaths Worldwide 200,000 deaths/yr Vaccine-toxoid-need booster Caused by Clostridium tetani Obligate anaerobic, endospore forming, gram pos. rod found in soil Soil contaminated wound- deep puncture Very potent exotoxin Organism is non-invasive Tetanus treatment and prevention Treat with anti-toxin and antibiotics If symptoms already apparent-treatment much less effective-supportive therapy Prevent with vaccine Water The most important common source of infection Potable-water that is fit for human consumption Polluted-rendered useless for particular purpose Human pathogens in water usually come from human feces E. coli is indicator organism (coliform group) Coliform bacteria Fac. aerobic, gram neg, non- spore forming rods that ferment lactose with gas Most are enteric bacteria E. coli Klebsiella pneumoniae Enterobacter Coliform test Water thru filter Filter on EMB plate Should be negative for Eosin methylene blue plate-selective drinking water (190,000 cases and >5000 deaths worldwide in 2008 (but only 5-10% of cases reported 12 cases in U.S. in 2005- food Shredding of intestinal lining due to enterotoxin “Rice-water stools” 22 liters fluid/day (~6 gal) Must replace fluids and electrolytes New numbers: 3.5 million cases/100,000 deaths per year. Haiti since 2010…>680,000 cases >8400 deaths Cholera treatment and prevention Oral water and electrolytes Antibiotics don’t help much Vaccines available but variable short term immunity Travelers-avoid untreated water or ice, no raw foods or shellfish Legionnaire’s disease Legionella pneumophilia Grows in water Water distribution systems, cooling towers, large AC units Aerosols but not person to person Legionnaire’s disease Mild symptoms-Pontiac fever Self-limiting, no need to treat Older populations-pneumonia Treatment-antibiotics (usually IV) Typhoid fever Caused by a strain of Salmonella (S. typhi) in contaminated food or water Rare if there are good sanitation practices Bacteria multiply in macrophages-invade intestinal mucosa Symptoms last ~ 4 weeks Can be treated now with antibiotics Vaccine available Protozoa Giardiasis Giardia intestinalis – a protozoa Fecal-oral transmission of cysts Found in 97% of lakes ponds, streams of U.S. Trophozooite stage (15 mm) Water filtration usually eliminates but not Cyst stage (10 mm) chlorine or UV alone Filtration + boiling best SEM of small intestine of a gerbil infested with Giardia Giardiasis – symptoms and treatment Cysts attach to intestinal wall Explosive, foul smelling diarrhea, cramps, malaise. Stools have no blood or mucus. Patients can be symptom free carriers Drugs available (eukaryote) Diplomonad  Cryptosporidosis Cryptosporidium parva – a protozoa Very small cysts Common in cattle Cysts resistant to chlorine and UV (more resistant than Giardia) Responsible for ~ ½ recreational waterborne outbreaks Huge potable water outbreak a. Trophozoite in GI epithelium in Milwaukee 1993 b. Oocytes in feces (~3mm) (>400,000 people) Cryptosporidosis – symptoms and treatment Usually self limiting and mild diarrhea of 2 weeks Immunocompromised have much more serious disease-can have fatal complications Immunosuppressed due to drugs- discontinuation of drugs is recommended Protozoa Amoebiasis Amoebic dysentery Entamoeba histolytica infects colon Protozoa Tropical regions 400 million worldwide 100,000 deaths Several hundred U.S. Fecal-oral (cysts) 30 or more bowel movements/day Drugs available but not great Protozoan Meningoencephalitis Naegleria fowleri Free living amoeba in soil – contaminates water Enters nose and burrows to brain Death within a week if not caught Outbreaks often occur in summer-people swimming in warm, shallow, fresh water Trophozoites in brain  Louisiana Issues Neti Pot Warning After Two Fatal Infections (ABCnews 12/11/2011) Use distilled or previously boiled water for neti pots https://www.usatoday.com/story/news/health/2018/12/10/after-brain-e ating-amoeba-death-what-water-safe-neti-pot/2263240002/ Water borne helminths Life cycle of a blood fluke Schistosoma Schistosomiasis 200 million cases Correlates with conditions for snails Humans wade in water Inflammation Bloody urine Guinea worm life cycle Crustacean - Copepods 1-2 mm –can be filtered from water Guinea worm Were 10 million infections per year Drinking water contaminated with copepods/larvae After ingestion - the larvae grow for a year, becoming thin thread-like worms, up to 3-feet-long No drugs or vaccine-Must gradually remove worm from blister- can take 1 month Going into water with blister releases larvae Carter Center Jimmy Carter foundation hoped to eradicate Guinea worm by 2000. Started 1986 https://www.cartercenter.org/health/guinea_worm/ind ex.html Will be first eradication without drugs or vaccines- simply education and drinking water improvements Recent development-guinea worm also infects dogs  FYI Guinea worm eradication progress 2019-54 cases 2020-27 2021 15 2022 13 2023 13