Microbio Final.docx

Parasite an organism that gets some or all of it's food from the host, at the host's expense (only the parasite benefits) Epibiosis (phoresis) 2 organisms that are nutritionally independent of each other have a facultative relationship together epibiont: smaller organism using another for transport...

Parasite an organism that gets some or all of it's food from the host, at the host's expense (only the parasite benefits) Epibiosis (phoresis) 2 organisms that are nutritionally independent of each other have a facultative relationship together epibiont: smaller organism using another for transport basibiont: larger organism that carried epibiont ex: stalked ciliate using copepod for transport Commensalism small symbiont eats for/benefits from larger symbiont which is neither harmed or benefited ex: flagellate eating unwanted bacteria off of fish Helminth general term used to describe worm-like parasites can be used to describe multiple unrelated phyla those who sexual reproduce tend to have longer life cycles Intermediate Host (IH) temporary host that is REQUIRED for parasite development Paratenic (Transport) Host (PH) temporary host that is NOT required for parasite development and is typically just used for transportation ex: Toxicana canis entering mouse prior to entering a dog, rather than just going directly into the dog and skipping the mouse Aberrant (Abnormal) Host (AH) infected organism that is not typically a host for that parasite, resulting in slow or incomplete parasite development, but has possibility of still being transmitted to DH ex: Toxicana canis infecting humans rather than dogs Dead end (Incidental) Host intermediate host that is unable to transmit the parasite (to the DH) so the parasite's life development is incomplete Final Host organism where parasite reaches sexual maturity organism can sometimes be the same as the DH Definitive Host (DH) organism where parasite sexually reproduces organism can sometimes be the same as the final host Toxoplasma gondii: Life Cycle 1: sporogony (oocysts) within feces 2: IH (human, mouse, mammal, or bird) ingests this 3: develops into tachyzoite (rapidly replicating stage that causes acute infection) or bradyzoite (slow replicating stage that is a dormant cyst and causes chronic infection) w/in IH 4: cat (DH/final host) ingests either form via eating the IH and tachyzoite can turn into bradyzoite or vise verse while within the cat IH: location of asexual reproduction DH: location of sexual reproduction Nematode Lungworm: Life Cycle 1: larva within cat (DH) feces is eaten by snail/slug (IH) 2: bird (PH) eats the snail/slug 3: cat eats the bird and larva develop into adults within the lungs and lay eggs 4: eggs turn into larva and enter the cat's intestines where they are defecated into the environment example of indirect life cycle w/ PH (birds are used for transport and not development) Parasite (general info) endoparasite: live within host ectoparasite: live outside of host ectoparasites reproduce faster (because many are asexual), reduce host fitness, and typically do not kill their host parasites can use host for food, water, habitat, heat, transmission (and anything to help keep them alive) Direct Life Cycle AKA: Simple life cycle parasite only have 1 host (the DH) to complete it's life cycle and ONLY sexual reproduction happens w/in DH life cycle only involves the DH and the environment host can be specific or broad spectrum ex: nematodes within ruminance, and Toxocara canis within dogs Indirect Life Cycle AKA: Complex life cycle involved 2 or more hosts to complete their life cycle host specific or broad spectrum can have final host, DH, and/or IH ex: Dirofilaria immitis (heartworm) which requires mosquito as IH and dogs as DH Dirofilaria immitis: Life Cycle 1: mosquito ingests microfilaria from infected dog blood 2: microfilaria develop into larva w/in mosquito (IH) 3: mosquito inject larva into dog (DH) 4: larva develop into adults (within the heart) and lay microfilaria w/in the dog's blood AKA: Canine Heartworms Leucochloridium paradoxum: Life Cycle 1: adult flukes (trematodes- flatworm parasites) are located within birds (DH) 2: birds shed eggs in feces and snails/gastropods (IH) ingest this fecal matter 3: larva develop and migrate to the snail's eye tentacles and cause pulsations within the eye (while snail is still alive) 4: pulsations attract birds to eat the snails AKA: Zombie Snails Hypobiosis state of arrested development where the parasite is in stasis until environmental conditions improve and are optimal again can be seasonal (ex: nematodes) or due to host immune response, or due to increased adult parasite numbers, inhibiting larvae Predilection Site prefered site within or on the host that is an optimal food source, and avoids the host immune system this typically relates to pathology of parasites Aberrant Site abnormal site within the host that the parasite does not normally infect typically correct host but wrong location ex: sheep botfly (Oestrus ovis) infecting the brain rather than the prefered nasal cavity Trophic Transmission traveling to another host once current host is eaten some parasites will increase the host's chances of getting eaten by removing their predatory avoidance and attracting predators instead ex: stickleback fish infected with nematodes, swimming to water surface to attract birds ex: Toxoplasma gondii causing "fatal feline attraction" within infected rodents who lose their fear of cats (DH- ONLY species where sexual reproduction occurs) "-iasis" vs "-osis" iasis: presence of parasite (sub-clinical) osis: presence of disease caused by a parasite (think: Oh no disease) can start with "-iasis" and lead to "-osis" ex: coccidiasis vs coccidiosis Demodex (arachnida= 8 legs) ectoparasitic mite that is not typically contagious but can cause immune suppression naturally present in low numbers (on healthy dogs) diagnosed using deep skin scrape direct life cycle via replication within hair follicle but can spread to nursing puppies can cause blepharitis within human eyelashes w/ symptoms of crusting around eyelashes, and is treated with tea tree oil. This infection is NOT zoonotic and is caused by human specific species- found in Iceland Monogenea Class (Phylum Platyhelminthes): General Info ectoparasitic flatworm that lack true body cavity or coelom and live on fins, skin, gills of fish, and on the eyes of exotics (hippos, frogs, reptiles) simple digestive system with mouth, pharynx, intestines, but lack anus and have to use flame cells for waste hermaphrodites that mostly produce eggs but can be viviparous have poorly developed suckers and use HOOKS modernly related to cestodes and ancestrally related to bellaria (free-living flatworms) direct life cycle= cage culture fish problem size: 2-3cm Monogenea Class (Phylum Platyhelminthes): Examples Udenella spp is only monogenean that lacks hooks due to living on copepods who live on fish, to get food from the fish (ectocommensal/hitchhiker relationship with copepod) Gyrodactylus: viviparous (have live young) and very deadly as they can have multiple generations of parasites within 1 host Benedenia seriolae infecting amberjack fish and feeding on their external epithelial cells (size: 1cm or microscopic). They are non-viviparous and have eggs attached to filaments Vectors (ectoparasites): General Info fleas and ticks carry pathogens within their salivary glands which are transmitted with bites arachnids: ticks and mites insects: fleas (wingless flies), lice, flies Vectors (ectoparasites): Examples Ticks transmit ehrlichia (rickettsial bacteria genus) Deer Ticks transmit Anaplasma phagocytophilum (bacteria that infect WBC's) Mosquitos transmit heartworms (parasitic round worms) Trematode: General Info AKA: digeneans, digenean flukes, aspidogastrea endoparasites within phylum platyhelminthes oral and ventral suckers doral ventrally flattened (leaf like) lack an anus and use flame cells for waste hermaphroditic but can cross reproduce NO direct life cycle broad host spectrum but almost always use gastropods (snails) as IH large operculate (cap/lid used for larva exit on their) eggs= they are heavy and require sedimentation for diagnosis DH is typically a predatory fish or sometimes birds can be zoonotic (if metacercaria is eaten from environment) Trematode: Examples Fasciola hepatica AKA: "common liver fluke" or "sheep liver fluke". Infects sheep, mammals, humans, cattle Amphimerus species: Liver flukes in Ecuador that infect dogs, cats, humans Fasciola hepatica: General Info Pathology: pipestem liver and chronic infection Symptoms: anemia, bottle jaw Diagnosed with fecal antigen test or fecal sedimentary in combo with symptoms size: 4cm can be zoonotic trematode Fasciola hepatica: Life Cycle metacercaria (larval stage) burrows through intestinal lining and perineal cavity it then migrates through the intestines and liver through bile ducts where it develops into adult flukes IH: freshwater snails in family Lymnaeidae Final Host: ruminants Trematode: Simple Life Cycle 1: Adult is within final host (DH) 2: Egg is dropped into environment and develops into miracidium 3: IH ingests this and it develops into rediae and then into cercaria 4: It is released into the environment as metacercaria 5: Final Host (DH) eats metacercaria from the environment 6: Within DH, it develops into an immature adult and then an adult Alaria Americana: Life Cycle 1: cercariae penetrate 2nd IH where they become infective metacercariae 2: This is ingested by PH or DH (dog) 3: Within the DH, it develops in the lungs and then lives in the intestines trematode specific to North America (commonly in carnivorous mammals) requires IH +/- PH DH options: coyote, skunk, dog, lynx, fox, bobcat, marten, cattle Trematode: Life Stages miracidium: penetrates snail/gastropod (IH) rediae: developmental stage in IH cercaria: free swimming stage with flagella and can encyst itself to become metacercaria metacercaria: can be present in 2nd IH (fish), PH, or the environment (water). If a 2nd IH is used, it is considered a complex life cycle. (size: 150microns) adults: typically found in rumen/intestines, lungs, blood, or liver (bile ducts) and cause an inflammatory response Cercarial dermatitis AKA: swimmer's itch due to aberrant infection within humans (ideal host are birds) causing allergy symptoms genus schistosome causes schistosomiasis within humans trematode infection: cercaria stage causes infection Acanthocephala Phylum: General Info AKA: Thorny headed worms lack mouth and digestive system: Absorb nutrients from host's digested gut contents via their integument (skin) size: 10cm sister group to rotifers (freshwater zooplankton) IH: invertebrates (ALWAYS) adults live in digestive tract (small intestines) and are not typically pathogenic ALWAYS have a complex life cycle and broad spectrum hosts Cystacanth: life stage that is ingested to cause infection (AKA: resting stage) Diagnosis: eggs in feces (sometimes sub-clinical) Francesco Redi described them as worms with proboscis (retractable structure used for attachment to intestinal walls) arms with hooks Acanthocephala Phylum: Example at RUSVM, cystacanths were found encysted within the muscle of mongoose and scrotum of monkeys Abnormality 1: cystacanths are only in IH to await for transmission to DH (however neither of these species have natural predators in St Kitts and it is therefore unlikely the parasite would be ingested by a predator to enter DH) Abnormality 2: IH of this parasite are ALWAYS invertebrates (which neither of these animals are). Abnormal because cystacanths are only in the IH and because they were present in these animals, it suggests they think they are in the IH. Abnormality 3: This parasite's DH are only vertebrates which both animals are. However, the adult stage of the parasite is normally found within intestines of the DH- which is not where they were found within these 2 animals (also no adult stage was found). infection was from same species: Oncicola venezuelensis most likely these were dead end hosts and cat's are the DH