Intro To Parasitology 2010

 

Introduction to Medical Parasitology  Victoria Basa-Dalay, MD, MSc July 1, 2010

 

 A t

the end of the Session , the student must be able to: Differentiate Differentia te the three symbiotic relationships in Microbial World Define: Parasitology Parasitology, , Parasite, Host and other commonly used terms in Parasitology P arasitology Discuss the taxonomic classification of parasites with examples Given the life cycle of a parasite: identify its important components Give its simple preventive and control measures

 

LEAD Rules of the Session

Listen to learn and learn to listen

Expect the unexpected ctive participation is encouraged  A iscuss and Share your thoughts

D

 

BASIC TERMINOLOGY & PRINCIPLES

Symbiosis  A n

association between two different  species of organisms Primarily aim for obtaining food from one or both member of the relationship Commonly known as as Living  Living together Has no overtones of benefit or harm Includes a wide diversity of  associations

 

Symbiotic Relationships

Parasitism Unilateral benefit

Degree of  harm to host

Commensalism

Benefit of  the species

Shelter and food

Mutualism Reciprocal benefit

Symbiosis

closeness of association

 

ssessment: Comment on this table Self- A ssessment:

Type of Symbiotic Relationship

Mutualism

Organism

+ (Benefited)

Commensalism - (Not  Harmed) Parasitism

Host  

- (Not   Harmed) +( Benefited)

++ (Benefited) - ( Not   Harmed)

 

Parasitology ´ The sof  cie nce thawhich t dealare s wphysiologically ith speciali liz zed group animals dependent on ot othe herr or orga gani nism sms s for their survivalµ. Neva & Brown, 1994 Medicall Para Medica Parasit sitolog ology: y: ´The science that deals with parasites (organisms) that take up their abodes, temporarily or permanently, on or within its hosts (other living organisms) for the purp pu rpos ose e of  pr proc ocur urin ing g fo food od an and d pr prot otec ecti tion on,, resul re sulti ting ng in a re rela lati tion onshi ship p th that at can harm harm or lead to disease development in host µ.

 

Definition Parasite Organisms ranging from microscopic to macroscopic Exhibit great diversity in morphology and physiology  A nimals nimals depending on bigger organisms for food and shelter Has intimatewith relationship walmost ith the always host  obligatory  A lways lways harmed the host 

 

ricoid  s   Ascaris  lumb e Com pete petes  f or  or   a vaila bl e nut ri  ri ent  s   ent s  si nc e i t  t a bsor bs   su gars , pro te tei ns  a nd   f a  a t  ts  s    f rom  rom  the f ood  ood  Obs t  r  uc t  s    the gu t  truc  ts  t  by bolus  o f worms  a Dama ge ges  vi t  tal    l   or ga ns  duri ng ng erra t  t ic  ic   mi gra t  tio  i o n

 

SURVIV AL F ACTORS OF 





P AR ASITES

Parasites Parasi tes have succes successfu sfully lly adapt adapted ed to (all?) (all?) environmental niches in hosts Parasites best adapted are least pathogenic Typically with long-term/chronic/intimate parasite-host relationships

 

Types of Parasites to REMEMBER EndoEnd o- vs Ecto Ecto-p -par aras asit ites es Obligate vs Facultative Parasites Permanent vs Transient/ Temporary Parasites Erratic vs Spurious Parasites Zoonotic Parasites /  A ccidental ccidental Parasites

 









CONDITIONS NECESS ARY  FOR SUCCESSFUL ENDEMIC P ARA SITISM SITISM Rese eservo rvoir ir of infe infectio ction n  sou source rce of infe infectio ction n Means of transmission from infected to susceptible, new hosts A bility bility

to invade and successfully reside in  new hosts A bility bility

to reproduce

 

Definition Host The

bigger organism in which the parasite lives Provides the nourishment and protection

 /shelter needed by the parasites May tra transf nsfer er or har harbor bor the org organi anism sm temporarily or permanen permanently tly Provide appropriate environment for growth and reproduction Maybe harmed, killed , not affected or they may even benefit in association with other organism

 

Types

of Host

Definitive

Host

the se sexua xuall or the ma matur ture e sta stage ge of the parasite site where the sexual reproduction occurs, if present.

Host¶s

Body: Man, Pig

Harb arbors ors

Eg.

Man - Asc scar aris is Dog - Dypilidium Mosquitoes - Pl Plas asmo modi dium um

DEFINITIVE HOST ST:: Man or Pig

External Environment

 

Types

of Host

Intermediate

Host

Harbors

the asexual or the immature/ larval forms of the parasite Site where the asexual reproduction occurs Eg.

Snails - Echinostoma Pig - Tric richi hine nella lla an and d Taenia Man - Plasmodium Crustaceans rustaceans    Paragonimus

In Humans

In Snails or Crustaceans

 

Types

of Host

 Vector  An invertebrate animal which

Humans

Mosquito

week s

transmits a parasitic organism from one host to another

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Figure 7.3 7.3 Life Cycle of  Plasmodium  Plasmodium spp. spp.

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Types

of Host

 Vector

Mechanical Vector

 An

invertebrate animal which merely transfer parasitic organism from one host to another by their appendages Eg. flies, cockroaches

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invertebrate which harbor theanimal parasitic organism internally with further development Eg. m osq  osq u  u itoes, itoes, bu gs gs

Gam et ocyt es

Macro gam et ete e

Merozo i t es

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(Exflagellation) Zygot e Fert i l i zat i on Ooki net e

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Life

cycles of

Human Parasites

L

In the Body of  Host

Direct ife cycle

No intermediate host is needed/required in transmitting the parasite

Host

External Environment

Host

from one host to another  A . Parasite may be

immediately infective upon leaving the host

B. Parasite may still need an external environment (soil) to develop into an infective stage A.

B. Trichiuris

Trichomonas

 

Life

cycles of

Human Parasites

Indirect Life cycle  A t

least one (1) intermediate host is needed or a vector is required in transmitting the parasite from one host to another Eg. Fasc iolopsis iolopsis Plasmod iu m

In the Body of  Host

In the Snail and Water Plants

 

Components Portal of  Entry:

of the Life Cycle

Mouth

Infective Stage: Embryonated Egg

Path of  Migration:

Mode of Transmission: Ingestion of the infective stage

Blood ungs Intestine

Habitat:

External Environment : Soil ( 0 - 4 days)

Small Intestine

Portal of  Anus

Exit:

Diagnostic Stage: Egg in Feces

 

GENERA LIZED LIZED PROTOZO A N LIFE C Y CLE CLE Trophozoite

Cyst 

 

LIZED PROTOZO A N LIFE C Y CLE CLE GENERA LIZED Trophozoite

Trophozoite

 

LIZED SPOROZO A N LIFE C Y CLE CLE GENERA LIZED Trophozoite Sporozoite Schizont  Gametocyte Gametes Oocyst  Ookinete

 

Life Cycle

of Ascaris lumbricoides

Prophylactic

Mode of Transmission: Ingestion

Treatment of  Cases Cooking food properly

Habitat:

Path of  Migration: Early Treatment of Cases

Blood ungs

Avoid

Intestine

use of  night soil

Small Intestine

Early Treatment of Cases

Proper excreta disposal

Proper excreta disposal

Early diagnosis

 

Taxonomic Groupings of Parasites Unicellul Unice llular, ar, eukary eukaryotic otic parasites parasites-- Prot Protozoan ozoan Phylum

Sarcomastigophora Phylum  Apicomplexa Phylum Microspora Phylum Ciliophora

Multic Mul ticell ellula ularr parasite parasitess - Met Metazo azoan an Helminths Phylum  Aschelminthes Phylum Platyhelminthes

 A rthropods rthropods Phylum  Arthropoda

 

Common terms used in Protozoans Trophozite rophozite:: the active,feeding and growing stage in most protozoans; the mature form Cyst yst::

the sac-like stage in protozoans, usually the infective stage Oocyst ocyst::  A  thick-walled

structure in which sporozoan zygotes develop and that serves to transfer them to new hosts like in mosquitoes.

 

Types

of Parasites

 According

to Taxonomic Group Protozoans

Amoeba

Subphylum Sarcodina Move by pseudopodia ‡

Eg. Entamoeba  Entamoeba  Naegleria  Acanthamoeba

Reproduce

Subphylum Mastigophora Move by flagella ‡

iardia, Eg. G iardia, Trypanosoma,  Leishmania, Trichomonas

Asexually by Binary

Flagellates

 

Subphylum Sarcodina t  oly t   t  ica  Ent  amo eb eba  his t  

Disease: A mo  mo eb ebic  dys ent  ery   / coli t   t  is  Mode of Transmission ransmission:: i n  nge g   es t   tio     n  n  o f  f cys t   ts     from   nt  ami n  na     t   ted    ter    co nt   a oo d o r wa t   f oo  Infective Stage: cys t   ts       Diagnostic Stages: cys t   t  s   a n  nd   t  ro ph te    s  pho zoi t  

H

n 

abitat: Fx: a n  ncho  c  ho colo  vy  sa uc e; e; f las  las kksha ped ped ulc er er Dx: Fecalysis  Tx: Met  ro n  ni  i   da zol e

 

Subphylum Sarcodina N a  aeg   gl eria  f owl  owl eri  e

Disease: A cute cute  A mo eb ebi c Meni ng ngo encephali t  ti i s  i n N or  or mal  Ho sts sts Mode of Transmission ransmission:: Penet ra  ra t  tio  i o n of  the na sal  muco sa  t o  o   the brai n Infective Stage: t ro  ro ph pho zoi te te Diagnostic Stages: t ro  ro ph pho zoi tes tes Habitat: brai n r esent  anset) i o ns io  al   Fx: epsent  tset) ns li ke ke fa t  t al  menC i ng nli gni i t  tci i  sal (pra  i d o a  n t  pho zoi tes tes i n CSF/ Brai n Dx: Tro ph t i i ssue ssue Tx: A mph mpho te teri ci n B

 

Types

of Parasites

 According to Taxonomic Protozoans

Subphylum Mastigophora

Group

Flagellates

Move by flagella ‡

Eg. G iardia, iardia, Trypanosoma,  Leishmania, Trichomonas Reproduce

Asexually by Binary fission

 

Subphylum Mastigophora

iardia  lam blia  G iardia  Disease: G iardia  iardia si s Mode of Transmission ransmission:: i ngest  ngest i ion o   n of cysts f r  r om   cont ami  ami na te ted  wa te ter  a nd  food  Infective Stage: cysts Diagnostic Stages: cysts a nd  t r  rophozo o   phozoi tes tes Habitat: small  i ntest  ntest i i ne ne Fx: stea r to tyor he hei c stool ; d ysente ysente Dx: Fecal ys ysi s a nd  Enter otest  otest  Tx: Met r  ron o   nida zo zol e

 

Subphylum Mastigophora n osoma  osoma  cruzi  T  rypa n  Disease: Cha ga ;s  Dis eas e; e;  A m  me   rica n  nT   T   rypa     nosomiasis  n  o   somiasis  Mode of Transmission ransmission:: bi te tes  o f  f  r ed edu vii d bu g (T  ria t  toma,)  o   ma,)  acyc lic   Infective Stage: m et  et acyc  rypomas t  rypomas    o Stages: t  t i ig te te Diagnostic epimas t  t i ig   o te te Habitat: s ki n  n,   mucous  m em bra n  ne; e   ; bloo d Fx: c ha goma,Roma n n a a      si gn ; m eg egaco lo n n ;  car diomyopa th thy  ( mos t  t  s erious   ) sm ear ; bo dy  flui ds  Cxd Dx: Bloo  z n  i  d   azo le u imo x Tx: ben z  ni  le or  n i if  f  ur    r t  t imo 

 

Subphylum Mastigophora T  rypa n  n osoma  osoma  bruc ei  r  ica n  o Disease: A f  frica  n   T  rypa n  nosomiasis    somiasis , ng   Sic kn ess  Sleepi n  Mode of Transmission ransmission:: bi te tes  o f  f  i n  set    t s  se   fly ( G lossi n  a nfe f  ec ted ted t s  e na     ) m et  acyc lic   Infective et acyc  t rypomas  rypomas t  ti i  gStage: o te te Diagnostic Stages: epimas t  ti i  go te te Habitat: bo dy  flui ds ; bloo d o c e; Fx: som n n o     lle en c  e; si ez ezur e; e; coma  Dx: Bloo d sm ear ; bo dy  flui ds  NNN m ed edia  a ate Tx:Pen t  tami    mi di n  ne   is eth ethio n  n a  t  e a n  nd   Su dami n  n 

 

Subphylum Mastigophora n as  nalis    lis   T  richomo n  as  vagi n  a Disease: T  richomo n  niasis  i  asis  Mode of Transmission ransmission:: dir ec t  t  s exu exual  co n  nt  t   ac  ac t  t  ro pho zoi te Infective Stage: t ro  te r ro  o  ho  Diagnostic Stages: t  p zi te te Habitat: vagi n  a ate na      a n  nd   pros t  t a  t  e Fx: vagi n n al  a   l  pros t  ta a    t   tic  i c  discharg e n d   i t  c  hi n n e   ss  discharg e a n tchi  nal    l   a Dx: Wet sm ear  o f vagi n  discharg e ro n  i   da zol e Tx: Met ro  ni 

 

Types

of Parasites

 According

to Taxonomic Group

Protozoans Phylum  Apicomplexa No

locomotory organ Have a complex life cycle Eg. Plasmodium, Isospora, Toxoplasma. Cryptosporidium P

hylum Microspora No locomotory organ Intracellular Parasite Eg. Microsporidia

Sporo oa

With al altern ternaating sexu exual al and as asexu exual al reproduction  

Phylum Apicomplexa

P lasmodium  lasmodium  spp . Disease: Mala ria ; Bla ckw ckwa ter ter Fever Mode of Transmission ransmission:: bi te tes  o f  f i nfecte nfected  femal e a nop he o  heli ne ne mosqui t  t o  Infective Stage: spo ro zoi te tes  Diagnostic Stages: blood   s t  ta  a    ge ges  Habitat: blood  Fx: tert ia  ia n a nd  qua rt  rt a a  n p er eriodi ci ty ty Dx: Blood  sm ea r ne; qui ni ne; ne; Tx: Chlo roqui ne; qui ngh nghaosu 

 

Phylum Apicomplexa

t  osporidium  spp . C ryp  ryp t   Disease: Malabsorp t   t  io n sy ndrom e; ryps t   tosporidiosis     e; C ryps  Mode of Transmission ransmission:: t  h dri nk nki ng ng or  co nt  act  wi t   co nt  ami na nat  ed  wat  er  Infective Stage and Diagnostic Stages: sm all, all, sporu la lat  ed  oo cys t   t  wi t   t  h 4 t  

sporo zoi  es  Habitat: Sm all t  i ne all i nt  es t   ne Fx: cachexi a and  s eve ever e di arr hea hea Dx: Fecalysis  taz    o xan Ni t   xanid e; e; fluid  and   elect  ro ly t   te    r ep lace lacem en ent   

Tx:

 

Types

of Parasites

 According

to Taxonomic Group

Protozoans Phylum Ciliophora

Move by beating of  many cilia Mostly include variety of free-living and symbiotic species Eg. Balantidium coli 

R eproduce eproduce as asexu exually ally by Bin inaar y Fi Fiss ssion ion

Ciliates

 

Phylum Ciliophora

ala nt   B ala  nt  idium  coli  Disease: B ala  ala nt   nt  idia si s Mode of Transmission ransmission:: d ri n  n ki n  ng   o r co nt   nt  ac t   t  wi t   t  h co nt   nt  ami n  n a  at   t  e    d  wa t   ter    Infective Stage and Diagnostic Stages: c ys yst  s a n  nd  d      t  ro ph pho zi t   tes    ne   Habitat: La rge rge Int  est  i n  n g Fx: dia rrhe rrhea  amo n  slau gh ght  er hou se se wo rkers rkers Dx: Fecal ys ysi s Tx: Tet  rac ycli n  ne*,   *, wi t   th    e t   n 

Me ro  ida zol e* e*

 

ypes o  According

aras es to Taxonomic Group

Helminths

Class: Nematoda Intestinal and tissue inhabiting species

Phylum: Aschelminthes Elongated, cylindrical worms Unsegmented Sexes are separate Reproduction by: Oviparous

Eg.

 Ascaris,

Enterobius

Viviparous

Eg. Trichinella Trichinella,, Filarial Worms

Parthenogenetic Eg. Strongyloides Infection

by:

Ingestion of Eggs Eg.  Ascaris, Trichuris Skin Penetration of larvae Eg. Hookworm Vector-borne

Eg. Filarial Worms Ingestion of of encysted encysted larvae Eg. Trichinella

 

HELMINTH/WORM TERMINOLOG Y   Adults dults:: sexually reproductive stage in the life cycle stage Larvae arvae::

developmental or asexually

reproductive stage in the life cycle Eggs ggs::

spherical/ oval stage that protects the

zygote &/or embryo in the life cycle Cysts ysts::

usually an encapsulated larval stage found in tissues of an intermediate host 

 

HELMINTH/WORM TERMINOLOG Y  Monoecious/hermaphroditic: both sexes in Monoecious/hermaphroditic: one body Dioecious: with sexes separate; males & Dioecious: females Parthenogenesis arthenogenesis::

ability to produce offspring without fertilization of eggs

 

Worm-terms, continued Oviparous viparous::

production of eggs, discharged from uterus of female Ovoviviparous voviviparous::

production of eggs which hatch prior to discharge from uterus of female  Viviparous: production of embryos/L1 larvae,  Viviparous: no rigid encapsulation of embryo

 

Nematodes of Medical Importance Habitat Gastrointestinal tract  Small Intestine

Genera  A scaris, scaris, A ncylostoma ncylostoma

Necator,Trichinella, Large Intestine

Capillaria Trichiuris, Enterobius

Skin Sk in// Ti Tiss ssue ue ne nem mato tod des

Onc ncho hoccer ercca, Loa Loa,, Gnathostoma, Trichinella

Blood and Lymphatic Nematode

Wuchereria, Brugia

CNS Nematode

A ngiostrongylus ngiostrongylus

 

Class: Nematoda H ookworm  ookworm .

Disease: A ncyl om iasis, ncylo st  st om  iasis, Necat or  or iasis iasis Mode of Transmission ransmission:: r ati orm   Sk in in penet r  atio no f filar if  if orm  lar vae vae Infective Stage: Filar if  if orm  orm   Lar vae vae Diagnostic Stages: Ova Habitat: Sm all all Intestine Fx: Gro und und itch; Iro n deficiency anem iia a Dx: Fecalysis Tx:

Mebendazo le le

 

LIZED NEM A TODE TODE LIFE C Y CLE CLE GENERA LIZED  A dults dults

Eggs

Embryos L1 L2 larva L3 larva L4 larva L5 juvenile

 

Filarial Worm Life Cycle DH  (Man)  Vector(Mosquitoes) dults microfilariae L1 L2 larva  A dults L4 larva L5 larva

L3 larva

 

W  uch er eria  ba n  n crof   crof  t  i   t  

Disease: Lympha  ic  fi laria si s Mode of Transmission ransmission:: tes    of   nf   f  e    c t   ted    to     es bi t    i n  mo squi t   es Infective Stage: Thir d st  a ge ge lar va e (L3) Diagnostic Stage: Microfi laria e (L1) Habitat: Lympha t   tic     syst  em; ski n  n   a n  nd   gla n  nds d   s Fx: elepha nt   nt  ia si s Dx: Bloo d smear  Tx: Meben da zo le le

 

Comparison of Nematode Eggs

 

Types

of Parasites

 According to Taxonomic Group Helminths Phylum: Platyhelminthes

Class: Tremato Trematoda da

Flattened,

leaf-shaped

or cylindrical worms ( Schistosoma) Unsegmented Hermaphroditic Reproduction by: Oviparous

Infection

Eg.

S chistosoma chistosoma

by:

Ingestion of metacercariae Eg. F asciola, asciola, Echinostoma, Paragonimus, Clonorchis Skin Penetration of cercariae Eg.

S chistosoma chistosoma

 

Trematodes/Flukes Generalized Fluke Life Cycle dults  A dults

in Man (D ( DH )

Egg

Miracidium (embryo)

First IH (Snail) Sporocyst &/or Redia larva Cercaria

Second IH ( veg vegeta etatio tions, ns, crab crabs, s, fish, fish, snail snail)) Metacercaria

 

Typical Trematode Life Cycle 2nd IH

1st IH

 

Flatworm helminths, continued

Schistosomes/Bloodflukes Generalized schistosomal life cycle

Man (DH) Male & Female  A dults dults Egg

Miracidium embryo

Snail (IH) Sporocyst larvae

Cercaria

 

Life Cycle of Sch is t   t  os oma s p. p.

 

Comp ompaaris rison on  of  of S Schi chissto tossom omaa vs. other  f luke ukes¶ s¶ Life Cy Cyccle

 

Trematode Eggs

 

Types

of Parasites

 According to Taxonomic Group Phylum: Platyhelminthes Helminths Elongated, flattened, ribbon-like worms Class: Cestoda

Segmented Hermaphroditic Reproduction by: Oviparous

Infection

Eg. Taenia

by:

Ingestion of encysted larvae Eg. Taenia, Echinococcus Poutrice Eg. Diphyllobothrium

 

Sub-groups of Cestodes Pseudophylidea

Cyclophyllidea

 

Generalized Pseudophyllidean Life Cycle  A dults dults

in DH SI Egg

Coracidium Procercoid larva

Copepod First IH

Plerocercoid larva

 A dults dults

Fish Second IH

in DH SI

 

Pseudophyllidea Pseudophyllidean n (Diphyllobothrium latum) life cycle

 

Generalized Cyclophyllidean Life Cycle  A dults dults

in DH SI

Egg with Onchosphere/Hexacanth Embryo Larva (Cysticercoid, cysticercus, coenurus, hydatid) in IH

 A dults dults

in DH SI

 

Taenia species life cycle

 

Cestode  A ffecting ffecting Man

 

Species Taenia saginata Taenia solium

Size 35 Qm. Rang Range, e, 31 31-43 -43 Qm.

Shape Spherical with thick striated shell.

Color Walnut brown.

Stage of Development When Passed Em Embr bryo yona nate ted. d. 6hooked oncosphere present inside a thick shell.

Specific Features and Variations Thick, striated sh shell ell.. Eg Eggs gs of  of T. T. solium and T. saginata are indistinguishable and species identification should be made from proglottids or scoleces. "Taenia "Taenia"" spp. should be reported if only eggs are found.

Hymenolepis nana

47 Qm x 37 Rang Range, e, 40 40-60 -60 Qm x 30-50 Qm.

Qm.

Oval. She Oval. Shell ll c cons onsist ists s of  2 distinct memb membra rane nes. s. On inner inner membrane are two small "knobs" or poles

Colorless, almost transparent.

Em Embr bryo yona nate ted. d. 6hooked oncosphere inside shell.

Polar filaments.

from which 4 toand 8 filaments arise spread out between the two membranes. Hymenolepis diminuta*

Dipylidium caninum*

*

72 Qm. Rang Range, e, 70 70-86 -86 x 60-80 Qm.

Round or slightly oval. ova l. Str Striat iated ed outer outer membrane and thin inner membrane with slig slight ht pole poles. s. Spa Space ce between membranes may appear smooth or faintly granular.

Yellow.

Em Embr bryo yona nate ted. d. 6hooked oncosphere inside shell.

Resembles H. nana but lacks polar filament filam ents. s. Poles Poles are rudimentary and often hard to see.

35-40 Qm. Rang Range, e, 31 31-50 Qm x 27-48 Qm.

Spherical Spheric al o orr ov oval. al. 515 eggs (or more) are enclosed in a sac or capsule.

Colorless.

Em Embr bryo yona nate ted. d. 6hooked oncosphere inside shell.

Eggs are contained in a sac or capsule which ranges in size from 58 Qm to 60 Qm x 170 Qm. Occa Occasi sion onall ally y capsules are ruptured and eggs are free.

Oval or ellipsoidal with an inconspicuous operculum at one end

Yellow to brown.

Unembry Unemb ryon onat ated ed.. Ger Ger minal cell is surrounded by a mass

Egg resembles hookworm egg but has a thicker shell and an

of yolk cells which completely fills inner area of 

operculum.

Qm

Usually found in lower animals, only occasionally found in humans.

Diphyllobothrium latum

66 Qm x 44 Rang Range, e, 58 58-76 -76 Qm x 40-51 Qm.

Qm.

and a small "knob" at the other end.

she shell. ll. Germina Germinall cell cell is usually not visible.

 

Cestode Eggs

 

Types of Parasites  According to Taxonomic Group Phylum  Arthropoda 4

Morphologic Characteristi Characteristics: cs: Segmented body parts: head, thorax and abdomen Three to Four pairs of   jointed appendages Covered by hard chitinous exoskeleton Bilaterally symmetrical body

 

Medical Significance of  A rthropods rthropods to Man  As

direct agents of diseases Dermatitis  due to insect Dermatitis insect bites ( Caterpillars, bugs, etc) Injury to sense organs  (wasps and bees ) Infestation of insect Infestation insect larvae - myiasis Entomop ntomophobiahobia- fear of insects insects (eg. Cockroaches) Envenomization ( Sting of scorpions) Ectoparasites ( Scabies, Pedic ediculos ulosis is and Crab louse infn)

 A

vectors or disease transmitters Mechanical vectors Biological vectors

 

Types

of Host

 Vector Mechanical Vector  An

invertebrate animal which merely transfer parasitic one host organism to anotherfrom by their appendage a ppendages s Eg. flies, cockroaches

it s o   al no phelin phelin e M o s q u i to to q 

p 

r 

s

q

t 

q 

u 

Biological Vector

Gam et ocyt es

Trophozoi t es

Eg. Mosquito in Malaria

Schi zont s

 An

invertebrate animal which harbor the parasitic organism internally with further development Eg. m osq  osq u  u it  oes, bu gs gs

Gam et ocyt es Gam et ocyt es

Macro gam et ete e

Merozo i t es

M a lla arial 1.  

 

a ro

‘

’ 

M ic ro g am e tes

(Exflagellation) Zygot e Fert i l i zat i on Ooki net e

v 

€ 

ƒ 

† 

‚ 

sm

n

u

w 

.

 

.

 

.

 

x 

ed  

lo o d 

 

„ 

‡ 

y 

y 

r an sm ission r an s usion ‚ 

ha r i n g o   ‚ 

… 

ee d l es

Oocyst

o ng e n i t a l t r a n s e r

r o m  m o t h er er to

‚ 

‚ 

e tu s

ol d s t a g e

‡ 

2. H o t s t a g e 3.   ea t i n g s t a g e

H

„ 

“ 

ˆ 

r

‰ 

p t o z o i t es

‰ 

pn o z o i te

Sporozoi t es

Sporozoi t es

p 

Sporozoi t es

Figur e 7. 3 Li e   ” 

 

Types

of Parasites

 According

to Taxonomic Group

Phylum  Arthropoda Class Pentastomida eg. Tongue worm Class Crustacea : crabs, crayfish, copepods Class Arachnida : spiders, scorpions, ticks, mite Class Insecta : Order Anoplura : human lice Order Hemiptera : reduviid bug Order Diptera : Housefly O

: ants, bees, rder Hymenoptera wasps Order

Siphonaptera : fleas

Diptera : mosquitoes, flies Class Chilopoda : centipedes Class Diplopoda: millipedes Order

– 

 •

 —

i te s o   em emal al e A no phelin phe lin e M o s q u i to to

l e o  Plasmodium   s pp. pp. ” 

r 

 s

 

Importance of Studying Medical Parasitology To know the different parasites affecting man To know how to prevent transmission of  these parasitic infections to man

 

Life Cycle

of Ascaris lumbricoides

Prophylactic Treatment of  Cases

Mode of Transmission: Ingestion Cooking food properly

Habitat:

Path of  Migration: Early Treatment of Cases

Blood ungs Intestine

Small Intestine

Early Treatment of Cases

Proper excreta disposal

Avoid

Proper excreta disposal

Early diagnosis

use of  night soil

 

Types

of Parasites

ccording  A ccording

to their Mode of Transmission and their Preventive Measures

C

T

1. ontact ransmitted 2. Soil-transmitted 3.  Arthropod-trans rthropod-transmitted mitted (Vector-borne) 4. Snail-transmitted 5. Food/ Animal-transmitted 6. Water-transmi Water-transmitted tted

 

Types

of Parasites

 A 

ccording to their Mode ofMeasures Transmission and their Preventive

1. Contact Transmitted Infection is transmissible directly from person to person Eg. Enterobius vermicularis Trichomonas

vaginalis Sarcoptes scabei Pediculus capitis

Preventive measures:  A void void

contact with infected individuals Immediate treatment  with infecd individuals

 

Types

of Parasites

n  t   t  

T   n 

n 

 Accordi  smissio  Mod  fMe   ra    a n  d    t   h o  e ir h Per ir  eve eve veo f  ve asur  es  nd    g  nt  i e 2. Soil-transmitted The infective stage become infective after a period of incubation in the soil. E  g .  Ascaris  lum bricoid es 

T  richuris  t  richiura 

 An cylos  cylos t   toma     al e  duod en al  u N eca t   t  or  am erica n  nus    s  S t   g tro     n  ngyloid    yloid es  s t   te    rcoral es 

Preventive measures:

ro pe r  dis posal  o f  P pen  f  huma  n  fec es   Avoid  us e o f  igh t   f n igh  t   soil   as  fer t   tili     ze zer  t   t   n 

n 

ro  rom   P ec tio   to  f s ki  f rom  f  co  nt  ac t   nt     wi t   h       co nt   a nt  ami n  na    t   t  e    d  soil 

 

Types  A 

of Parasites

n 

T   n 

n 

ccordi  o e ir  h smissio  t h  Mod  fMe   ra    a n  d   t h  ht o   P  er  rir   eve eve t i ie ve veo f  asur  es  nd    g  n t 

3.  Arthropod-transmitted

Preventive measures:

Infective stage develops in the arthropod intermediate host which transmits the infection

n  o f t h  r  uc t  i o n  h e Des t  truc  tio  ar t  thropod  h   ropod  br ee eedi n  ng  g      plac es  Us e o f  f ch emical  

by biting by or when ingested man

prophyla xis 

lasmodium  spp . E  g . P lasmodium  W  uch er eria  nosoma  o   soma  T  rypa n 

 

Types  A 

of Parasites

n  t   t  

n 

n 

cco rd a ure ra  dn   h o  ei r Mo  di eve de Tras    e i rh Preve veo fMe usmissio  res  ni d   g t   nt  

4. Snail-transmitted Infective stage develops in the snail intermediate host or second intermediate host after partial development development in the snail E  g .

Schis t   tosoma     E  chi n  nos  o   s t   t  oma 

Preventive measures:

Des t   tru    c t   tio     n  n  o f  f s n  nai  a   i l vec t   to     rs   A voi d co nt   nt  ac t   t   wi t   th       i n  nfe f  ec t   t  ed o r co nt   nt  ami n  n a  at   t    ed t  

bo di es  o f wa  ers 

 

Types  A 

of Parasites

n  t   t  

T   n 

n 

ccor a  smissio  dn   h o  Mo  di eve de fMe   ra    e ir h   P er  rir   eve eve veo f  asur  es  ni d   g t   nt  

5. Food/ Animal-transmitted Infective stage develops in animals whose flesh is an important food item of man E  g . T  richi n  ne   lla  spiralis 

T  a en ia  ia  solium  apillaria  philippi n  sis  C apillaria  ne   n sis  P arago  arago n  nimus  i  mus  w es t   te    rma n  ni  i   

Preventive

measures: P rop  rop er  coo ki n  ng  g      o f f oo  oo d li ke t   a n  nd   f ish  ish  ke m ea t  

 

Types  A 

of Parasites

n  t   t  

n 

n 

ccordi  Mod  Tra    a n  d    t   h o  e ir h Per ir  eve eve veo fMe ve as usmissio  r es  nd    g  nt  i e

6. Water-transmitted Infective stage of the parasite develops develops in the external environment and usually reaches man through ingestion of contaminated water. iardia  lam blia  E  g . G iardia  Ent  amo eb eba  his t   t  oly t   tica    

Preventive

measures:

ng       o f  n ki n  ng      wa t   te    r  g g Boili n  f dri n 

 

Types

of Parasites

 A 

ccording to their Mode ofMeasures Transmission and their Preventive

1. Contact Transmitted

Preventive

measures:

2. Soil-transmitted 3.  Arthropodtransmitted 4. Snail-transmitted

HEALTH EDUC ATION

5. Food/ Animaltransmitted 6. Water-transmitted

transmission of the parasite belongs to.

- an essential component of control regardless of the the category of

 

Self- A ssessment ssessment Questions Given the following parasites, name their respective mode of transmission: 1.

Schistosoma spp.

2. 3. Trichomonas Ascaris 4. Giardia 5. Capillaria 6. Entamoeba 7. Taenia solium 8. Wuchereria 9. Sarcoptes scabei 10.Plasmodium

1. Snail-transmitted 2. Contact-transmitted 3. Soil-transmitted 4. Water-transmitted 5. Fo Foodod- tr transm ansmitt itted ed (fis (fish) h) 6. Water-transmitted 7. Food-tr Food-transmitted ansmitted (pork) 8. Vector-borne 9. Contact-transmitted 10. Vector-borne

 

Sharing Time What are the important things that I learned from this session?

 

³I

will make you wise and show you where to go.  I will guide you and watch w atch over you!´ says the

ord.

Psalm

2:8

Thank You!