MLS Review - Parasitology - Introduction & Trematodes

MEDICAL LABORATORY SCIENCE REVIEW CLINICAL PARASITOLOGY: INTRO & TREMATODES OUTLINE • • Introduction • o Parasitology o Biological Relationships o Components of Parasitism Taxonomy Trematodes o General Characteristics o Classification of Flukes based on Habitat o Blood Flukes o Leaf Flukes PARASITE • • • INTRODUCTION PARASITOLOGY • • Parasitology - an area of science which deals with the study of organisms living permanently or temporarily on or within another organism. Clinical Parasitology – concerned primality with animal parasites of humans as well as their medical importance o Morphological characteristics is one of important ways to determine parasites BIOLOGICAL RELATIONSHIPS • • Symbiosis - association between two different species living together • Mutualism - both host and organism will benefit • Commensalism - only one is benefitted and the other is neither benefitted nor harmed • Parasitism - one organism depends on another organism (host) for survival and other organism is damaged/harmed at its own expense o Man-parasite relationships Host Organism Mutualism Benefitted Benefitted Commensalism Neutral Benefitted Parasitism Damaged/Harmed Benefitted COMPONENTS OF PARASITISM HOSTS • • • • The organism that harbors the parasite. Man is the usual host of parasites Types of Hosts: o Definitive – harbors adult/sexual stage of parasite o Intermediate – harbors immature/larval stages of parasite which may be asexual o Paratenic – harbors stage which is infective to man, ▪ Remains viable but no further development ▪ Transmission is also possible o Reservoir – harbors same species of parasite, important source of infection for susceptible host o Accidental – unusual host ▪ Harbors the parasite which is usually not found and infectious to the host; ▪ Pass through but is not usually pathogenic ▪ Considered as incidental host ▪ Eg. ratworm - usually invade rat but can sometimes invade man Factors involved in the transmission of parasites: o climate conditions, behavioral traits, host sociality, population density, diet, habitat, age, sex, host immunocompetence, supplementary feeding, and animal translocations • The organism that depends on the host for survival. According to their effect to the Host: o Pathogenic - cause harmful effect/injury to host o Non-pathogenic/Commensal - do not cause injury to the host; incapable of setting up disease process in man; causes no harmful effect/further damage According to Location/Habitat: o Endoparasite - inhabits within the body of the host ▪ Most parasites fall under this category ▪ Leads to infection ▪ Eg. Ascaris lumbricoides (soil) and Entamoeba histolytica (contaminated water) o Ectoparasite - inhabits the parasite without penetrating the host; ▪ Lives outside the body or the body surface ▪ Leads to infestation (parasite lives outside host) ▪ Eg. ticks and mites o Erratic - parasites that invades a part of the body where it is not usually found. ▪ Eg. Entamoeba histolytica (usually in intestine but can be hepatic & cerebral) According to Host: o Obligatory/Obligate - cannot survive without host ▪ Eg. Plasmodium spp. o Facultative - live as parasitic form or free-living parasite; can survive with or without host ▪ Eg. Strongyloides stercoralis o Accidental - unusual host is being infected ▪ Eg. Echinococcus granulosus (usually seen in sheep but can be seen in man) o Aberrant Parasite - host becomes a reservoir where parasite infects host but they don’t develop further ▪ Wandering parasite ▪ Found in location where they don’t usually occur ▪ Eg. Trichinella spiralis (pork muscle worm, usually in mast cells of muscle tissues of pigs, can invade muscles of man) ▪ A. lumbricoides (usually in intestine, but can be seen in liver) o Hyperparasite - another parasite as the cost ▪ Eg. Ctenophalides canis - Dipylidium caninum According to Host - Other Types: o Permanent - parasite made host its permanent habitat ▪ Lives its entire lifetime/life cycle (early life to maturity) on one host o Incidental/Accidental - occurs in unusual host o Intermittent - some parasites that just visit the host during feeding time ▪ Eg. malaria, mosquitoes o Periodic - larval and adult stages are passed in two different hosts o Transitory - larval stage is passed on a host and adult stage is free-living or parasitic o Copozoic/Spurious ▪ Can pass in alimentary tract without harming host; ▪ Focuses on acquiring nutrients; ▪ Can be excreted through fecal excretion o Zoonotic - non-human parasites but may cause human infection ▪ Animal parasites (dog ticks, etc.) o Pseudoparasite - debris or artifacts that are mistaken for parasites 1 o • • • • • Coprophilic ▪ Parasites easily/readily cultivated at room temp ▪ Dies out at 37C o Hematozoic – blood-dwelling parasites, requires blood for survival ▪ Eg. Malaria o Cytozoic – found attached to cells intracellularly ▪ Eg. Entamoeba o Coelozoic - lives in body cavities of hosts o Enterozoic - lives inside the lumen of the intestine According to Structures: o Protozoa – small, unicellular o Animalia – larger, multicellular Important Terms: o Vector - transmit parasite from one host to another ▪ Arthropods o Carrier - harbors the particular pathogen, presents certain signs and symptoms ▪ Asymptomatic - carrier presenting no symptoms o Infection - invasion by endoparasite o Infestation - invasion of ectoparasite o Sporadic - parasites make a short visit to host to acquire nourishment o Endemic - condition found among certain/particular persons/groups o Epidemic - condition found widespread in communities o Pandemic - condition found widespread across nationalities/continents o Superinfection - an infected individual is reinfected with same pathogen causing massive infection Types of Life Cycle: o Direct - only one host is visited (definitive host) o Indirect - requires two or more hosts (1 or more intermediate and 1 definitive hosts) o Intermittent/Temporary - visits host during feeding time ▪ Eg. Anopheles spp. o Erratic - lives in organ different from one it usually lives ▪ Eg. Entamoeba histolytica, A. lumbricoides Mode of Transmission of Parasites to Man: o Thru skin bites (vectors) o Thru the Digestive system (ingestion) ▪ Most common mode of transmisison o Thru the Reproductive system (sexual contact) o Thru the Respiratory system (inhalation of infected droplets, saliva, sputum) o Thru the placenta (pregnancy, transplacental) o Thru contact with the animals (zoonotic transmission) Methods of Parasite Control: o Use of insecticide and other chemicals o Use of protective clothing o Use of protective netting o Proper water treatment o Good personal hygiene o Proper sanitation practices o Proper handling, cooking, and protection of food o Avoidance of unprotected sexual relations TAXONOMY • Kingdom Animalia o Subkingdom Metazoa ▪ Phylum Nemahelminthes (roundworms; simplest life cycle: ova → larva [rhabditiform → filariform] → adult) • Class Adenophorea o Order Trichurida ▪ Trichuris trichiura ▪ Trichinella spiralis ▪ Capillaria philippinensis • Class Rhabditea o Subclass Secernentia ▪ Order Ascaridida, • Ascaris lumbricoides • Toxocara canis • Toxocara cati • Anisakis spp. ▪ Order Oxyurida • Enterobius vermicularis (best way to collect is perianal swab) ▪ Order Strongylida (hookworm) • Necator americanus • Ancylostoma duodenale • Ancylostoma braziliense • Ancylostoma caninum • Angiostrongylus cantonensis (non-hookworm) • Angiostrongylus costaricensis (non-hookworm) ▪ Order Rhabditida • Strongyloides stercoralis (threadworm; unique life cycle) ▪ Order Spirurida • Wuchereria bancrofti (elephantiasis) • Brugia malayi • Loa loa (eye worm) • Onchocerca volvulus • Mansonella ozzardi • Mansonella perstans • Mansonella streptocerca • Dirofilaria immitis • Drancunculus medinensis ▪ Phylum Platyhelminthes (Cestodes & Trematodes; tapeworms) • Class Cestoidea o Subclass Cestoda ▪ Order Pseudophyllidea (Longworms) • Diphyllobothrium latum • Spirometra spp. ▪ Order Cyclophyllidea (Tapeworms) • Taenia solium • Taenia saginata • Hymenolepsis nan • Hymenolepsis diminuta • Dipylidium caninum • Echinococcis granulosis • Class Trematoda (leaf-like; diecious) o Subclass Digenea ▪ Order Plagiochiformes 2 • ▪ ▪ ▪ • • Paragonimus westermani (lung invader) Order Echinostomatifermes (liver flukes) • Fasciola hepatica • Fasciolopsis busko • Fasciola gigantica • Echinostoma ilocanum Order Opistorchiformes • Chlonorchis sinensis (liver) • Opistorchis felineus (liver) • Opistorchis viverrine (intestinal) • Heterophyes heterophyes (intestinal) • Metagonimus yokogawai (intestinal) Order Strigeiformes (blood flukes) • Schistosoma japonicum • Schistosoma mansoni • Schistosoma haematobium • Schistosoma mekongi • Schistosoma intercalatum Kingdom Protista o Subkingdom Protozoa ▪ Phylum Sarcomastigophora • Subphylum Sarcodina o Class Lobosea ▪ Order Amoebida • Entamoeba histolytica (amoebiasis; pathogenic) • Entamoeba coli • Entamoeba nana • Iodamoeba butschii • Entamoeba gingivalis • Entamoeba dispar • Entamoeba hartmanni • Entamoeba polecki • Acanthamoeba spp. (pathogenic) ▪ Order Schizopyrenida • Naegleria spp. • Subphylum Mastigophora o Class Zoomastigophora ▪ Order Trichomonadida • Trichomonas vaginalis • Trichomonas tenax • Pentatrichomonas hominis • Dientamoeba fragilis ▪ Order Diplomonadida • Giardia lamblia (most pathogenic) ▪ Order Retortomonadida • Retortamonas intestinalis • Chilomastix mesnili ▪ Order Enteromonadida • Enteromonas hominis ▪ Order Kinetoplastida (tissue-eating) • Leishmania donovani (visceral) • Leishmania tropica • Leishmania braziliensis • Trypanosoma cruzi ▪ ▪ ▪ Trypanosoma brucei gambiense • Trypanosomabrucei rhodesiense Phylum Ciliophora • Class Ciliatea o Order Trichostomatida ▪ Balantidium coli Phylum Apicomplexa • Class Sporozea o Subclass Coccidia ▪ Suborder Haemosporina (bloodborne) • Plasmodium falciparum • Plasmodium malariae • Plasmodium vivax • Plasmodium ovale • Plasmodium knowlesi (recent discovery) ▪ Suborder Eimeriina (sporozoans; small size) • Toxoplasma gondii • Cryptosporidium parvum • Cyclospora cayetanensis • Sarcocystis • Cytoisospora belli o Subclass Piroplasmia ▪ Order Piroplasmidora • Babesia microti • Blastocystis hominis Phylum Microspora • Encephalitazoon intestinalis • Enterocytozoon bieneusi TREMATODES GENERAL CHARACTERISTICS • • • • • • • • • Also known as flukes or leafworms or flatworms (under Digenea) Hermaphroditic → Organ Dwelling → liver, intestinal, and lung flukes o Can cause injury/harm to host Dioecious → Skin Penetration → Blood Dwelling → Blood Flukes Hermaphroditic - having both male & female reproductive organs in one body Dioecious - male and female reproductive organs in separate individuals With oral and ventral sucker/ acetabulum o Oral sucker - at the anterior end of trematode o Ventral sucker/acetabulum - in the middle portion o Genital sucker - found in a few trematodes Man is always the definitive host Always require snail as intermediate host to finish life cycle o Blood Flukes: 1 intermediate host (snail) o Leaf Flukes: 2 intermediate hosts ▪ 1st - snail ▪ 2nd - marine life (fishes, aquatic plants, etc.) Trematodes requires intermediate hosts to finish life cycle 3 CLASSIFICATION OF FLUKES BASED ON HABITAT Habitat Blood Parasite Schistosoma japonicum (Superior Mesenteric Vein) Schistosoma mansoni (Inferior mesenteric vein) Schistosoma haematobium (Vesical Vein) Fasciola hepatica Biliary Tract or Hepatic or Liver Clonorchis sinensis Opistorchis felineus Intestinal Tract Common Name Oriental Blood Fluke Manson’s Blood Fluke Vesical Blood Fluke Sheep Liver Fluke or Giant Liver Fluke Chinese or Oriental Liver Fluke Cat Liver Fluke or Siberian liver fluke Giant Intestinal Fluke Garrison’s Fluke Fasciolopsis buski Echinostoma ilocanum Heterophyes Von-Siebold Fluke heterophyes Metagonimus Yokogawa’s fluke yokogawai Gastrodiscoides Colonic fluke hominis Respiratory Paragonimus Oriental Lung Fluke Tract westermani Pancreas Eurytrema Pancreas Fluke pancreaticum • Gastrodiscoides hominis - usually found in animals (pigs) but when it infects humans can cause serious health problems and even mortality • Eurytrema pancreaticum - one of the most common flukes in the pancreas and bile ducts of ruminants; closely related to Schistosoma japonicum Schistosoma japonicum Distribution China, Indonesia, Japan, and Philippines Pathogenicity Oriental Schistosomiasis / Katayamas disease Schistosoma Schistosoma mansoni haematobium Africa and South Africa and Middle America East Sample Diagnostic Stage Habitat Stool Ova with lateral spine Inferior mesenteric vein Coarse tuberculation, 4-5 testes Biomphalaria Planorbis Tropicorbis Integument of Male Stool Ova with lateral knob Superior Mesenteric vein Smooth 8-9 testes Intermediate Host (snail) Oncomelania quadrasi Intestinal Bilharziasis/ Schistosomal dysentery Urinary Bilharziasis/ Schistosomal Hematuria Agent of Carcinoma in the urinary bladder Urine Ova with terminal spine Vesical Vein Fine tuberculation 6-7 testes Bulinus Physopsis Pictures • Schistosoma japonicum • Schistosoma haematobium • Schistosoma mansoni BLOOD FLUKES • • • • • • • • • Non-hermaphroditic or Dioecious; Not leaf like Infective stage: cercaria Mode of Transmission: through skin penetration Adult female lays non-operculated embryonated egg which hatch to miracidium upon contact with water. Requires two hosts: o Definitive: man o Intermediate: snail Male adult is shorter & robust while female is longer & slender Male with gynecophoric canal/ schist (aka Bilharzia) o Opening from anterior to posterior part o Bilharzia opens up when copulation commences which grabs the female for copulation It is considered as the most romantic parasite Laboratory Methods o Stool Exam (Fecalysis, DFS) or Urinary Examination o Rectal biopsy or Liver Biopsy o Antigen testing (Circumoval precipitation test) o Skin test – Fairley’s SCHISTOSOMIASIS/ BILHARZIASIS • • Schistosomiasis/Bilharziasis/Swamp fever – name for infection of Schistosoma Cercaria - infective stage of Schistosoma 4 LEAF FLUKES • • • Hermaphroditic; leaf like Infective stage: metacercaria Mode of Transmission: ingestion of secondary intermediate host • Adult lays operculated egg o Operculum - hole/flap at an end • Requires 3 different hosts: (1 definitive & 2 intermediate) o Definitive: man o Intermediate host: snails o 2nd Intermediate Host: any marine life • Presence of 2 muscular shape suckers or distomata o Oral Sucker: Anterior end o Ventral Sucker or Acetabulum : Middle portion o Genital Sucker: mid lower portion ▪ Found in a few trematodes • No body cavity, circulatory and respiratory Organ • Alimentary tract resembles inverted Y with no anus 1st Intermediate Host 2nd Intermediate Host Fasciola Lymnea philippinensis, Nasturtuim officinale hepatica Lymnea swinhoei (water cress); Ipomea obscura (kangkong) Clonorchis Alocinma, Bulinus, Cyprinoid fishes sinensis Parafossarulus, Semisulcospira, and Melanoides Opistorchis Bithynia Cyprinoid fishes felineus Fasciolopsis Sementina and Aquatic plants: Trapa buski Hippeutis bicormis (water caltrop), Eliocharis tuberosa (water chestnut), Zizania (bamboo shoots), Ipomea aquatical and Nympheaea lotus (water morning glory) Echinostoma Gyraulus Pila luzonica (kuho), ilocanum convexiusculus and Vivipara angularis Hippeutis umbilicalis (susong pampang) Metagonimus Semisulcospira, Thiara, Plecoglossus, Salmo yokogawai and Hua (Salmonoid fishes), Ruchardsonium (Cyprinoid fishes) Heterophyes Pirenella and Cerithidia Fishes (mugil, tilapia), heterophyes Acanthogobius Paragonimus Antemelania asperata Fresh mountain crab, westermani Sundathelpusa Philippina and Parathelpusa Fasciola hepatica and Fasciolopsis buski Habitat Ova Clonorchis sinensis and Opistorchis felineus Adult Habitat Ova Adult Clonorchis sinensis Opistorchis felineus Liver - Chinese liver fluke, Liver - Cat liver fluke Oriental liver fluke With Developed Miracidium The eggs are operculated and possess prominent opercular ‘shoulders’ and abopercular knob. C. sinensis: thickened while O. felineus: thin “old fashioned lightbulb” Dendritic or spines Lancet shaped vitellaria & branched transversed vitellaria testes and lobed testes Fasciola hepatica Fasciolopsis buski May cause Liver rot in Largest trematode to sheep while Halzoun in infect man man Liver Intestinal • Size range: F. buski: 128-140 um by 78-85 um; F. hepatica: 128-150 um by 60-90 um • Shape: somewhat oblong • Egg contents: underdeveloped miracidium • Other features: presence of a distinct operculum Shoulder cephalic cone No shoulder cephalic and highly branched cone and branched intestinal, ovarian and intestinal, ovarian and testes ceca testes ceca 5 o Heterophyes heterophyes and Metagonimus yokogawai Habitat Ova Adult Heterophyes Metagonimus heterophyes yokogawai Smallest trematode to infect man; May cause autoinfection in man Intestine - can reach heart Intestinal & brain (fatal) can cause cardiac heterophysiasis • Average size: 30 by 15 um • Egg content: developing miracidium • Operculum: present • Shoulders: present but discrete • Small know: may be absent • Shell thickness: Heterophyes, thick; Metagonium, thin Presence of genital sucker A tiny layer of scaly or gonotyl spines covers the organism • Other features: prominent operculum with shoulders; obvious terminal shell thickening opposite operculum Adult: Coffee-bean shaped and outer skin covered with spikes. bilobed testes. • • • Discrete - means separate Any parasite with low molecular weight or small size can migrate to other parts of the body Echinostoma ilocanum • • • • Garrison Blood Fluke Crown of spine disks or Circum oral disk surrounding the oral sucker No marked symptoms produced other than intestinal irritation - still questionable whether it is active pathogen or not Eggs resemble Fasciola hepatica Paragonimus westermani • • • • • Can migrate to different parts of the body Considered as the wandered parasite Habitat: lungs Pathogenecity: o Paragonimiasis/ Pulmonary distomiasis – blood tinged sputum; mimics tuberculosis ▪ Hemoptysis - coughing out of blood o Cerebral paragonimiasis – presence of foamy like cerebral cyst Ova: Eggs are similar with Diphylobothrium latum o Size range: 78-120 um long; 45-60 um wide o Shape: somewhat oval o Egg contents: underdeveloped miracidum surrounded by a thin, smooth shell 6