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innate vs adaptive immunity
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role of cytokines
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parasitology
questions based on parasite life cycles and control. focus on macroparasites
| Question | Answer |
|---|---|
| innate vs adaptive immunity | innate: always/automatically in place (w/o exposure), physical barriers like skin, secretions/mucus layers; stomach acid, gut microbiome. recognized by TLRs adaptive: a specific learned response due to prior exposure; antibodies released from B cells |
| role of cytokines | communicative proteins (ie chemokines) of the immune system, bind to receptors to activate transcription factors. 'lead the way' for macrophages |
| 6 general ways to evade the immune system | hide inside host cells, prevent drawing attention by making a resting cyst, camouflage own At or use hosts, consistently change disguise, misdirect or manipulate immune response, neutralize threats using enzymes |
| ADCC | Antibody-dependent cell-mediated cytotoxicity; when invaders too larges, external attack to lyse and degrade (eosinophils) into small enough pieces for macrophages |
| fluke general life cycle and key life stages | egg -> miracidium ie swimmer -> int host snail:penetration(sporocyst -> redia) -> cercaria ie tadpole -> 2nd int host:trophic(metacercaria) -> def host(adult-> mate) -> eggs:fec-oral |
| Paragonumus westermani (hosts, transmission, found in, control) | snail (1st) pen. by miracidia -> FRESHWATER crabs/crayfish (2nd) pen. by cercariae -> humans & dogs/cats (def) eat crustacean with infective metacercariae; thorough smoking of crab, don't throw raw scraps to pets, waste infrastructure to prevent eggs |
| Clonorchis sinensis (hosts, transmission, found in, control) | snail (1st) eats infected feces -> raw FRESHWATER fish (2nd; may be multiple) -> humans & cats/dogs (def); thorough smoking/cooking/freezing of fish, don't throw raw scraps to pets |
| Fasciola hepatica (hosts, transmission, found in, control) | snail (1st) pen. by miracidia -> encyst on aquatic vegetation-> ruminants (livestock) or humans (2nd) eat veg -> adults live in bile duct and eggs are released in feces into water; drug treatment, clear aquatic veg., purge snails |
| what is the other Fasciola sp of note and why | F. magna because wild ruminants (elk, caribou) accidentally eat infected snails while grazing then can increase transmission to livestock |
| Schistosoma spp (hosts, transmission, found in, control) | miracidium pen. snail (int) -> NO REDIAE STAGE -> cercariae pen skin of human (def). haematobium bladder, mansoni large intestine, japonicum small intestine |
| List characteristics of the parasitic platyhelminthes | may have a free swimming stage for finding int. host, suckers/hooks to feed on epithelium, may have reduced digestive systems, alive adults less immunogenic than juveniles due to hiding proteins; eggs, juvenile stages, and adult 'heads' are diagnostic |
| Describe a generalized life history of trematodes | eggs released in water -> miracidia enter snail (1st) -> sporocyst and redia stage in snail -> exit snail and cercariae find fish/crustacean (2nd) -> metacercariae grow in 2nd -> vertebrate host eats 2nd int host -> adult develops, releases eggs in feces |
| What is the danger of prolonged infection by Clonorchis sinensis | members of the Opisthorchioidea farm host cells, leading to metaplasia and increased risk of cancer in the affected area. For C. sinensis, liver/bile duct cancer that is hard to detect often fatal |
| Contrast F. hepatica to other Echinostomids | cercariae encyst on vegetation not in another host |
| Describe why Schistosoma has a "unique" lifecycle among other digeneans | 2 generations of sporocysts instead of rediae stage, only one int host (direct penetration into definitive host > trophic) |
| Swimmer's itch causes and control | When bird schistosomes are released into bodies of water, people may be infected by the miracidium but because we aren't birds it can't progress and just causes an allergic reaction in the skin |
| Cestodes anatomy | adults have lost mouth/gut/anus, absorb nutrients thru tegument; scolex=head, strobila=body; body=repeating proglottids |
| How do fluke and tapeworm lifecycles typically differ? | flukes often have 2 int hosts, tapeworms 1 int if any. miracidia, sporocysts, redia, meta/cercaria vs oncosphere, cysticerci, plerocercoids, metacestodes |
| Which are the notable flatworm parasites impacting human and veterinary health? | Taenia saginata & solium, Diphyllobothrium, Echinococcus granulosus, Dipylidium |
| Explain how Tapeworms in the wild can be affecting host & non-host biodiversity? | reducing body condition of hosts increases risk of predation, may reduce prey populations with would increase population of whatever they feed on |
| Which emerging tapeworms are of importance in southern Ontario? | E. multilocularis in foxes (guelph) |
| Describe how control of echinococcus tapeworms are made difficult because of farming/cultural practices? | organs of livestock are often used as feed for dogs, when infected, the dogs can easily spread the disease to humans wildlife and livestock because its fecal-oral |
| Are adult tapeworms harmful to their hosts? | No, a few adults in a host usually takes only a negligible amount of nutrients--adults are only an issue in high numbers or in children/immunocompromised people |
| Describe how long-lived tapeworms can be a problem for infected hosts | hosts may not notice/know where they got it from, can increase risk of cancer (cell farming), increased transmission ie they're pumping out eggs for a long time |
| What are the dangers of having a hydatid cyst/Echinococcosis | Cysts are full of fluid, adult parts, and antigens, sudden burst cause cause instant death or coma |
| Outline challenges and strategies for controlling Echinococcus and the sylvatic cycle | because it can be harder to identify in livestock, infected scrap meats may be given to dogs without knowing, which infect the dogs and allow them to spread it to humans, wildlife, and livestock |
| Contrast Echinococcus spp. lifecycles | gran in ruminants and dogs, multi in rodents and foxes (dingoes, wild canids) |
| Contrast beef and pork tapeworm and how humans acting as intermediate hosts (but not definitive hosts) is a cause for concern | def host has adult worm which may be near negligible; int (juvenile stages) cause issues by migrating and encysting; beef worm does not recognize us as viable but pork worm can so continues life cycle and can brain cyst |
| Outline the life cycle of Dipylidium caninum | fleas (int) eat infected feces -> cats/dogs (def) itch and eat fleas -> may give to people (def) thru saliva -> pass cysts in feces |
| Differentiate between the larval stages of trematodes and cestodes. | ces: egg > oncosphere/coracidium > procercoid > metacestode > adult tre: egg > miracidium > sporocyst/redia > cercaria > metacercaria > adult |
| Are cestodes only transmitted by trophic transmission? Explain. | In a sense yes because the cysts must be ingested but other modes of transmission may play a role such as vectors and specifically fecal-oral |
| Describe the role of ____ in the life cycle of a parasite. [rostellum and hooks, hydatid cyst, pleurocercoid, coracidium] | 1. help attach to epithelium 2. tapeworm factory hidden by taking host antigens 3.infective mobile stage 4.first stage after egg, motile |
| Argue for the importance of "old" skills like diagnostic microscopy in the context of parasitology. | Microscopy is important to parasitology because it's an incredibly fast and cheap alternative to diagnosing parasites in blood, feces, any fluid sample, because eggs of spp are different |
| Describe how island nations (Japan, Cyprus) have experienced success controlling parasites. | Japan>Schistosoma: reduce snail habitat by clearing vegetation and lining ditches with concrete, horses>oxen Cyprus>Echinococcus: mass culling of dogs and livestock then close monitoring when bringing them back |
| Describe the danger of beef and pork tapeworm to a human. | beef: abdominal pain, diarrhea, weight loss (sees us as def) pork: localized symptoms based on migration, damage to brain and eyes possible (sees us as int) |
| Can an individual be infected with both juvenile AND adult stages of a parasite? Explain. | usually the juvenile stage is infective but the adult stage is the one that feeds an reproduces, so if you're consistently encountering a parasite you may have multiple life stages within you, but they'd all likely eventually become adults |
| What is sparganosis? | Rare condition where the metacestode of Diphyllobothrium latum infects human flesh often due to traditional medicine practices like poulticing where amphibians touch the wound |
| Schistocephalus solidus in stickleback changes host behaviour. Describe how this parasite affects host behaviour and how it increases chances of transmission. | It increases stickleback risk of predation by preventing behaviors like schooling and shadow avoiding as well as increasing things like flashing, which increases trophic transmission to birds |
| How do parasites impact their local environment? | they can change predator-prey dynamics (grasshoppers into river for charr) as well increasing biodiversity (biomass) and real estate (molluscs) |
| What are the potential health impacts of cestodes? What are the dangers to wildlife, or potential economic impacts? | GI symptoms or obstruction; wildlife populations may decrease , livestock and wildlife can transmit to each other |
| Why is the DALY an important metric to understanding helminth diseases of humans. | disability-adjusted life years: a measure of how many productive, functional years of life have been lost due to disease--important because many diseases are chronic and only disable instead of kill |
| Differentiate between direct and indirect life cycles in nematodes. | direct: often J3 infective, includes plant parasites. may crawl, cough, swallow indirect: arthropod int, vertebrate def. oviviparous |
| Contrast the two major species of human hookworm and their differences. How are they relevant historically and in modern day? | Ad: teeth clamps, lives only a yr but produce more eggs/day. old world Na: cutting plate, lives multiple yrs but less eggs/day. new world, likely introduced w slaves 'laziness' |
| Is Strongyloides stercoralis an obligate parasite, even though it survives and can carry out sexual replication in soil? Discuss why/why not. | no, all free-living and parasitic life stages are crucial to itself survival, it can't choose to forgo its parasitic stage rather it simply requires another step |
| A heavy infection of ascaris creates some unique problems for treatment. What are the dangers to the host and what are the challenges with treatment. | Because the worms are so large and can become so numerous, intestinal blockage can become so great that trying to pass the worm mass may be more harmful to the host (migration), rather surgery or a slow process of immobilizing and passing |
| Compare and contrast the life within the human lung for schistosomes and ascaris nematodes. | Schistosomes very briefly visit the lungs to migrate thru the blood and reside in veins (Katayama syndrome worse) Ascarids spend more time & cause more damage, then use cral-cough-swallow to get to the small intestine |
| Contrast the impacts to pet and human health of Dipylidium caninum and Toxocara canis | T. canis causes a worse disease and is common in cat/dog breeding situations, may cause complications in treatment because roundworms are very big D. caninum is not a huge issue is more likely to be passed to children but easily identifiable and treated |
| You are walking through Ontario Seed Company, and you overhear a canola farmer asking about biological controls for nematodes. They are looking to buy marigold. What symptoms might they be looking for in their plants and what advice could you provide? | look for necrotic tissue or weird root growth/galls, short stalks; screen plants before planting them in your garden, fungi or companion plants to attract predators for bio-control |
| You are at a Southern Ontario Provincial Park fish fry and you notice the fish is undercooked. Is there a threat of contracting a worm parasite? Describe what parasite (if any) you suspect, and what symptoms you would need to be mindful of. | since they likely didn't freeze before cooking, there is a slight threat of contracting a raw fish parasite. I would be most concerned about Diphyllobothrium latum. |
| Why is proper clothing an important element of parasite public health planning, and describe which types of parasites could be protected against. | reducing exposed skin can reduce the risk of bug bites proper shoes reduce penetration by geohelminth larvae |
| How do the three major types of raw fish helminths compare in terms of their symptoms? (how might we tell an infection with each apart) Where are you likely to encounter each | C. sinensis: liver damage, jaundice, (nausea, diarrhea, vomit, loss of appetite, abdominal pain); fw Asia D. latum: circulatory & muscle symptoms, irritability; fw America/Europe Anisakis: (GI symptoms) SUDDEN PAIN; pacific saltwater fish/cephalopods |
| Dracunculus mediensis, Dirofilaria immitis and Wucheraria bancrofti are all filarial nematodes. Contrast the life cycles, diseases, and transmission of these three worms. | D. med: transmitted by drinking infected copepods in water; burning blisters D. imm: mosquito vector; filariform becomes adult in heart/pulmonary arteries W. ban: " ; filariform becomes adult in lymph nodes |
| What are some practices that might be implemented in Canada to protect against pinworm? | monitoring at daycare, educating parents that have kids at daycare |
| Describe periodicity, or diurnal migration, in relation to pinworm, and filarial worms. | the microfilariae cyclically enter and exit the bloodstream based on when the vector is actively feeding; as pinworm has a direct life cycle and is fecal-orally transmitted, this doesn't apply |
| Why is the proliferation of outhouses in the southern United States in the early 1900’s, an important parasitology story? What was the result of this development? How did parasite biology affect outhouse design? | knowing that geohelminth larva can migrate up to 6ft in the soil lead to the design and standard 6ft depth which reduced transmission because people could walk around barefoot without stepping on worm larvae |
| Your roommate is travelling to sub-Saharan Africa. What types of precautions should they take to avoid becoming infected with a parasite. Use concrete examples from this course. | avoid infections like Guinea worm by being careful about drinking water malaria leishmania & trypanosomiasis using bug nets while sleeping, repellants and long sleeves when out schistosomiasis by avoiding putting bare skin in freshwater |
| Describe how drug treatment of filarial nematodes are complicated by co-infections. | Nematodes are really good at disguising themselves so when they randomly die the body can have an extreme maybe lethal rxn; treatment w/o knowing there's multiple could kill the non-target and complicate treatment |
| Why are reservoir hosts and emerging problem in the battle again Guinea worm? | it wasnt known that dogs were a reservoir for a while; its one thing to treat people but its another to try to treat strays that may be around in large numbers in some places |
| If Dirofilaria immitis were to suddenly become adept at infecting humans, what control measures would you suggest? | if heartworm could infect people there would probably be a campaign to control the mosquito vectors and deworm as many pets and strays as possible |
| How do the pork tapeworm and Trichuris pork worm differ? (life cycle, symptoms) | both acquired thru pork Taenia (cestode): produce measly cysts in brain/organs where ever it wants to migrate Trichuris (nematode): produce nurse cells (multiple gen in single host) |
| How might geohelminth control change if a phoretic fly became competent transport vectors of transited phases. | control would include reducing vector population (insecticide, breeding grounds), increased food hygiene |
| How do cestodes and acanthocephalans differ? How are they similar? | similarly secondarily simplified; acanthocephalans have no scolex just thorny proboscis also more round body AND have multiple hosts |
| Describe how nematomorphs can have community level effects on their surroundings | horsehair worms cause insects to jump into water en masse which can be a major food source for the aquatic ecosystem (deciduous -> coniferous charr fishery ex) |
| Describe specific control practices for biting flies: Tsetse vs Black vs Bot vs mosquito | (breeding ground destruction, personal protection) tsetse: sterile males, bright colored traps black: avoid standing water bot: livestock monitoring mosquito: bug nets, indoor protection, minimize standing water |
| Describe some morphological traits and behaviours that make bed bugs such effective temporary parasites | morph: flat, wingless, strong mouthparts for evading detection and staying attached behave: survive long periods without feeding, nocturnal, loving to hide |
| Describe how toxins, viruses, and teratocytes play a role in the life cycle of parasitoid wasps. Why are these wasps important | teratocytes (produce hormones), venom, and polydnavirus (turns off host responses) help the wasp inject eggs without the host rejecting the process; these wasps control insect populations which may benefit vegetation (protect from predation) |
| What parasite diseases may be carried by the various human lice and fleas. What controls could be suggested to prevent the spread of these insects in a school/shelter setting? | body lice: typhus, trench fever --rickettsia bacteria also relapsing fever flea: plague, D. caninum infected people need to be showered and given clean clothes, parents need to monitor their children |
| A zoonotic vector-borne filarial worm becomes widespread and is declared a global pandemic. What information do we need to know to guide public protective measures? | what vector, how does it reproduce what symptoms should be watched for how susceptible are humans, pets, livestock what stages of the life cycle can be controlled |
| Compare the various crustaceans covered that are economically important for fisheries in Canada. Which habitats/industries are affected? | gill(Ergasilids): not huge concern, freshwater fish(Caligids): marine (anadromous fish juveniles) sea Arugulus): all water, can be devastating to aquaculture L. branchialis (cod worm): cod, devastated C. exigua: snappers, no effect |
| At the grocery store you overhear a conversation about open-net aquaculture farms in the Pacific ocean and the potential for disease spread to local fish populations. The two people can't understand how this can be a problem. Explain to them. | fish farm allows parasite numbers to increase due to high density, passing native fish are at increased risk; worse if at estuary then anadromous juveniles entering saltwater likely to be infected |
| Parasites can lead to more diverse communities, and this is particularly true of the crustacean parasites. Describe this statement using examples from our course. | Trematode parasites of mollusks prevent them from digging deep into sand, creates more real estate for substrate-needing organisms |
| What diseases are caused by mites, in humans and animals? How are they transmitted | Mange (Demodectic mange): dry sores, bald spots, not contagious, may relate to immune issues. live under skin Scabies (Sarcoptic mange): itchy lesions, hair loss, contagious, in follicles |
| How can trophic cascades result from parasite outbreaks? | the infestation of a main herbivore may promote the growth of vegetation. of a main predator, the herbivore population increases, decreasing vegetation and increasing erosion |
| What are the four life stages of hard ticks? | egg -> larva (6 legs) -> nymph (8 legs) -> adult |
| Describe key differences between the life cycles and morphology of hard ticks (Ixodidae) and soft ticks (Argasidae). | hard: visible head & shield, 3-host life cycle, long feeding time, mates on host, many eggs, grassy areas soft: non visible head, no shield > wrinkly back, multiple hosts per life stage but short feeding duration, mates off host, few eggs, sheltered area |
| Explain how ticks acquire and transmit pathogens to their hosts. What makes ticks particularly effective disease vectors compared to other arthropods? | ticks get a disease by feeding on an infected host, diverse host interactions increases transmission, tick saliva already suppresses immune system, ticks live relatively long therefore transmits for long time |
| What are three effective strategies for reducing the risk of tick bites when spending time outdoors in tick-prone areas? | 1. protective clothing 2. insect repellant 3. tick checks when going into tick territory |
| What is the name of the bacterium responsible for Lyme disease, and which tick species is the primary vector in North America? | black legged tick, Ixodes scapularis Borrelia burgdorferi |
| What are the early symptoms of Lyme disease, and why is prompt treatment important? | bullseye rash -> flu symptoms -> spread to joints, heart, CNS -> cognitive difficulties, recurrent muscle/joint pain |
| Why are eosinophils an indicator of a worm infection? What role do they play? | worm -> IgE -> eosinophils; indicate a large invader that can't be targeted by phagocytosis, trigger ADCC to attack from the outside |
| Suppose Echinococcus rates greatly increased and pet populations were severely affected. What public health measures would you put in place, and what would the public need to know to limit transmission? | increase public education so people pick up after their dogs, control stray rates, don't give pets scraps, hygiene with pet litter/waste |
| explain helminth therapy / old friends hypothesis | IgE is responsible for rxn to allergies & worms, theory that helminths have been alongside humans so long we have a part of our immune system dedicated to them, and in modern times the theory that exposure to certain helminths as a kid decreases allergies |
| modes of transmission and general control methods | sexual: education vector: control habitats, increase wealth/infrastructure, repellants vertical: dont let it get to that point penetration: fecal-oral: education, infrastructure, trophic: |
| describe a parasite that doesnt infect humans but still has an impact on us | livestock/veterinary concern parasites like sea/fish lice, fasciola, dog heartworm, cod worm, as well as plant Pratlenchus/Meliodogyne: negatively affect things we closely interact with, may not get us sick but economic/psych impact |
| what would you include in an anti-parasite campaign/pamphlet for mothers that had just immigrated to canada | pinworm, Toxo - may get here whipworm? - may have brought lice in both directions; be watchful of itchiness before and after sending kids to school, make sure they know how to watch their hands well, always wash all linens after infection |
| discuss the advantage of being parasitized | cowbirds are brood parasites of Oropendola nests, however in areas without wasps/bees the Oros dont care because cowbird nestlings protect their own from bot fly parasitism |
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