Key Terms Symbiosis the living together in more or less intimate association or close union of two dissimilar organisms Parasitism a relationship between species where one organism the parasite lives on or in another organism the host causing it some Exam 1 Review harm and is adapted structurally to this way of life Types of Parasites Types of Hosts Facultative an organism that may resort to a parasitic lifestyle however it may not rely on a host for completion of its life cycle Obligatory a parasitic organism is one that cannot complete its life cycle without a relationship with a suitable host Endo parasite a parasite that lives within a host and causes an infection Ecto parasite a parasite that lives on a host and causes an infestation Definitive a host that supports the adult or sexually reproductive stage of a parasite This stage is necessary for parasite survival Intermediate a host that supports the immature or non sexual reproductive forms of a parasite There may be asexual reproduction This stage is necessary for parasite survival Transfer a host that can move or relocate parasite stages from one location another most often reproductive stages such as eggs Insects such as flies and cockroaches are good transfer hosts Vector a host that acts as an definitive or intermediate host for a parasite but more importantly transfers the parasite to the next Reservoir a host that serves as a source of infection and potential reinfection of humans and as a means of sustaining a parasite host within a population and ecosystem Terms Related to Host Parasite Relationships Exposure being in contact with an infectious organism Colonization the presence of an infectious agent bacteria on in a body surface like on the skin mouth intestines or airway without causing disease in the person Infection the invasion and growth of infectious agents germs on in the body Sign a sign is any objective evidence of a disease that can be observed by others for example a skin rash lump fever pulse blood pressure Symptom a symptom is subjective evidence of a disease that is apparent only to the patient for example back pain or fatigue Incubation Period the period between exposure to an infection and the appearance of the first signs and symptoms Latency the time from infection to infectiousness or being able to pass the infection Infectivity ability of an organism to establish an infection Invasiveness ability of an organism to spread to adjacent or distant tissues Pathogenicity ability to produce substances that damage tissues e g toxins Eosinophilia increased production of eosinophils a white blood cells that is part of host defense against parasitic infections Erythropoiesis increased production of red blood cells due to anemia caused by parasite feeding Neoplasia uncontrolled proliferation of cells due to excessive parasite induced tissue damage and repair Helminth infection general term to describe parasitic worm infection via contaminated soil Scientific name Common name Necator americanus New World Hookworm Mode of Infection Bare feet Nematodes Infective in Larval Stage Click scientific name for life cycle Normally found in Possibly migrates to Diagnosis Treatment Unique features Eggs in stool Albendazole Mebendazole Lungs during larval stage small int final destination Lungs during larval stage small int final destination Subcutaneous tissue Lunar cutting plates consumes 0 03 mL of blood day Fangs teeth consumes 0 26 mL of blood day Larvae remain in epidermis unable to enter cir system Observation Confined to skin in humans Albendazole Mebendazole Ivermectin orally or Thiabendazole cream Ancylostoma duodenale Old World Hookworm Ancylostoma caninum Creeping eruption dog Hookworm Ancylostoma braziliense Creeping eruption cat Hookworm Trichinella spiralis Pork worm Consume undercooked meat Small intestine Larva favor well oxygenated muscles Diet history ocular edema muscle biopsy serology No intervention or albendazole mebendazole if caught early Multiplication in host self cure 7 14 days normal cycle pig rat Strongyloides stercoralis Thread worm Skin penetration Lungs Ivermectin Complex life cycle free living cycle high degree of pathology Diarrhea to dysentary R larvae in fresh stool F larvae in older stool lung aspirations larvae in sputum Iron deficiency pica the urge to eat dirt Nematodes Infective in the Egg Stage Click scientific name for life cycle Scientific name Common name Mode of Infection Normally found in Possibly migrates to Diagnosis Treatment Unique features Enterobius vermicularis Pinworm Egg ingestion Large int Perianal area Appendix Vagina Mebendazole Large int Rectum prolapse Lungs during larval stage small int for adults Bile Pancreatic ducts Anal swab Scotch tape test Fecal smear Albendazole Thin egg shell with flat side primarily transmitted via fomites and where kids congregate Eggs barrel shaped heavy shell burrows into gut wall mucosa found in unprocessed night soil Eggs have thick shell found in unprocessed night soil adults feed on intestinal contents not you female produce 200K eggs day Life cycle Trichuris trichiura Whipworm Ascaris lumbricoides Giant Roundworm Loeffler s Syndrome Eosinophils infiltrating lung tissue as defense against larvae allergic reactions to molting fluid asthma like symptoms Tissue Nematodes Click scientific name for life cycle Scientific name Common name Mode of Infection Normally found Diagnosis Treatment Unique features Dracunculus medinensis Guinea worm Fiery serpent Contaminated water consumption Leg possibly damages knee joint Observation of ulcer Wuchereria bancrofti Bancroft s Filariasis Elephantiasis Mosquito vector Culex Anopheles Aedes Lymphatic channels Microfilaria in blood serology Loa loa Eye worm Deerfly Chrysops Freely moves through subc tissue Observation mi crofilaria in blood Matchstick Rubber band Metronidazole does not kill but aids in removal Diethylcarbamazine po ly therapy available with Ivermectin or Albendazole Surgical removal of capsule Ivermectin Nearly eradicated via stepwells copepods intermediate non filarial Blocking of lymph channels leads to tissue swelling filarial Calabar swelling Capsule formed from hypersensitivity reaction Onchocerca volvulus River blindness Black fly Simulium damnosum Skin biopsy looking for microfilaria Microfilaria in skin Parchment Skin Hanging Groin and eyes leading to corneal damage Nodulectomy removal of benign tumors Ivermectin kills larvae causing damage but not adults