Introduction To Medical Parasitology

Transcript

  INTRODUCTION TO MEDICALPARASITOLOGY  PARASITOLOGY  Area of biology concerned withthe phenomenon of dependenceof one living organism MEDICAL PARASITOLOGY  Concerned primarily with theanimal parasites of humans andtheir medical signicance TROPICAL PARASITOLOGY  Branch of medicine w/c dealswith tropical diseases and otherspecial medical problem of tropical regions BIOLOGICALRELATIONSHIPS SYMBIOSIS  Living together of unlikeorganisms COMMENSALISM   Two species live together andone species bets from therelationship without harming orbeneting the other o Eg Entamoeba coli MUTUALISM   Two organisms mutually benetfrom each other o Eg !ookworm PARASITISM  ne organism# the parasite#lives in or on another dependingon the latter for its survival o Eg Entamoeba histolytica ENDOPARASITE  $arasite living inside the body of a host INFECTION  $resence of and Endoparasite ina host ECTOPARASITE  $arasite living outside the bodyof a host INFESTATION  $resence of an ectoparasite ona host ERRATIC  %hen a parasite is found in anorgan which is not its usualhabitat OBLIGATE PARASITE   They need a host at some stageof their life cycle to completetheir development o Eg Tapeworm FACULTATIVE PARASITE  &ree'living state or may becomeparasitic when the need arises  ACCIDENTAL OR INCIDENTALPARASITE  A parasite establishes itself in ahost where it does not ordinarilylive PERMANENT PARASITE  (emains on or in the body of the host for its entire life TEMPORARY PARASITE  Lives on the host only for ashort period of time SPURIOUS PARASITE  &ree'living organisms thatpasses through the digestivetract without infecting the host HOST DEFINITIVE OR FINAL  $arasite attains se)ual maturity o Eg !umans INTERMEDIATE HOST  !arbors the ase)ual or larvalstage to parasite o Eg $igs# cattle PARATENIC HOST  $arasite does not developfurther to later stages  Able to infect anothersusceptible host o Eg $aragonimusmetacercariae RESERVOIR HOST  Animals that harbor the parasiteother than denitive#intermediate# and paratenichosts VECTORS   (esponsible for transmitting theparasite from one host toanother BIOLOGICAL VECTOR    Transmits the parasite only afterthe latter has completed itsdevelopment within the host o Eg Aedes mos*uito MECHANICAL OR PHORETICVECTOR   nly transports the parasite EXPOSURE AND INFECTION PATHOGENS  !armful and can fre*uentlycause mechanical in+ury to theirhost CARRIER   !arbors a particular pathogenw/o manifesting any signs andsymptoms  EXPOSURE  $rocess of inoculating aninfective agent INFECTION  Connotes the establishment of the infective agent in the host INCUBATION PERIOD  $eriod between infection andevidence of symptoms o Clinical ,ncubation period PRE-PATENT PERIOD  $eriod between infection orac*uisition of the parasite o Biologic ,ncubation $eriod AUTOINFECTION  (esults when an infectedindividual becomes his owndirect source of infection SUPERINFECTION OR HYPERINFECTION  !appens when the alreadyinfected individual is furtherinfected with the same speciesleading to massive infectionwith the parasite MODE OF TRANSMISSION   Skin penetratin o !ookworm o -trongyloides   Art!rp # o -erve as vectors andtransmit parasitesthrough their bites  Agents of malaria  &ilariasis  Leishmaniasis   Trypanosomiasis   Cn$enita% tran#&i##in o Can cross the placentalbarrier during pregnancy   To)oplasma gondii   Tran#&a&&ar' in(e)tin o $arasites may betransmitted through themother.s mik  Ancylostoma  -trongyloides   In!a%atin ( air*rne e$$# o Enterobius Se+,a% inter),r#e o  Trichomonas vaginalis EPIDEMIOLOGIC MEASURES EPIDEMIOLOGY  -tudy of patterns# distributionand occurrence of disease INCIDENCE  umber of new cases of infection appearing in apopulation in a given period of time PREVALENCE  umber of individuals in apopulation estimated to einfected with a particularparasite  CUMULATIVE PREVALENCE  $ercentage of individuals in apopulation with atleast oneparasite INTENSITY OF INFECTION  umber of worms per infectedperson o % (0 B1(2E MORBIDITY  Clinical conse*uences of infections or diseases thata3ect and individual.s wellbeing TREATMENT DEORMING  1se of anthelminthics drugs inand individual CURE RATE  (efers to the number of previously positive sub+ectsfound to be egg negative one)amination of stool or urine EGG REDUCTION RATE  $ercentage fall in egg countsafter deworming SELECTIVE TREATMENT  ,nvolves ,ndividual'leveldeworming with selection of treatment TARGETED TREATMENT  4roup'level deworming wherethe 5risk6 group to be treatedmay be dened by age# se) orother social characteristics UNIVERSAL TREATMENT  $opulation'level deworming COVERAGE  (efers to the proportion of thetarget population reached by anintervention DRUG RESISTANCE  4enetically transmitted loss of susceptibility to a drug in aworm population EFFICACY  ,s the e3ect of a drug againstand infective agent in ideale)perimental conditions andisolated from any conte)t EFFECTIVENESS  0easure of the e3ect of a drugagainst and infective agent in aparticular host$(E7ET,  A2 C T( L MORBIDITY CONTROL  Avoidance of illness caused byinfections INFORMATION-EDUCATION-COMMUNICATION .IEC/  !ealth education stategy thataims to encourage people to