Clinical Parasitology Lecture Notes PDF

CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 2: INTRODUCTION TO PARASITOLOGY I. PARASITOLOGY Termites gives habitat to flagella...

CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 2: INTRODUCTION TO PARASITOLOGY I. PARASITOLOGY Termites gives habitat to flagellates on their GIT, and flagellates digesting wood that consumed by termites. An area of science which deals with the study of organisms living permanently or temporarily on or Mutualism is a symbiosis in which two organisms within another organism. mutually benefit from each other like termites and the The branch of biology or medicine concerned with flagellates in their digestive system, which synthesize the study of parasitic organisms. cellulase to aid in the breakdown of ingested wood. It is the study of parasites, their hosts, and the relationship between them. 2. Commensalism: ✓ Benefitting: Parasites parasite derives benefit without reciprocating and ✓ Being harmed: Host without injury to the host or both. Concerned with the phenomena of dependence of ✓ Ex: Entamoeba coli can be found in intestinal one living organism on another. lumen and is being supplied with nourishment without causing any damage to the tissue of the DIVISIONS OF PARASITOLOGY host. ✓ One organism is benefitted from the Protozoology relationship and the other is being unharmed. Protozoans: small, unicellular organisms, which contain nucleus and functional Commensalism is a symbiotic relationship in which two organelles. species live together and one species benefits from the Helminthology relationship without harming or benefiting the other. Worms: larger, multicellular organisms, normally visible to the naked eye in their 3. Parasitism adult form. relationship where one organism, the parasite, lives Medical Entomology - Insects and arthropods in or on another, depending on the latter for its ✓ In life cycle of parasites most of them are survival and usually at the expense of the host. transported by vectors (insects and arthropods) ✓ Ex: Entamoeba histolytica derives nutrition from human host at the same time it causes OTHER TERMINOLOGIES amoebic dysentery. ✓ One organism is benefitted from the Medical Parasitology: concerned primarily with relationship and the other is being harmed the parasite that affects humans and their medical (there is pathological condition). significance, as well as their importance in human communities. Parasitism is a symbiotic relationship where one Tropical Medicine: branch of medicine which organism, the parasite, lives in or on another, deals with tropical diseases and other special depending on the latter for its survival and usually at the medical problems of tropical regions (wet & dry expense of the host. season). Tropical disease: an illness which is indigenous to PARASITES ACCORDING TO THE MODE OF or endemic in tropical area but may also occur in LIVING sporadic or epidemic portions in areas that are not Ectoparasites tropical. Parasite: lives on or in the host usually on a larger living outside the body of the host. organism which provides physical protection and ✓ Infestation nourishment. ✓ Ex: Head lice (Kuto), scabies Host: harbours parasite and gives nourishment. Endoparasites II. HOST-PARASITE RELATIONSHIP living inside the body of the host. Symbiosis (Relationship) ✓ Infection living together of unlike organisms, protection or Facultative parasites other advantages to one or both partners. able to live outside or inside the host and lead both Different kinds of Relationship to a free and parasitic existence. 1. Mutualism ✓ With or without host they can survive relationship is beneficial to both organisms. ✓ Pre-living stage: If they are not inside the host ✓ Ex: Termites and Flagellates on the Digestive system Page 1 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 2: INTRODUCTION TO PARASITOLOGY A facultative parasite may exist in a free-living state or Permanent parasites may become parasitic when the need arises. remain on the body of the host in all stages of its life Obligate parasite cycle. ✓ Only in one host completely dependent to the host for its existence throughout its life. A permanent parasite remains on or in the body of the host for its entire life. Most parasites are obligate parasites in that they need a host at some stage of their life cycle to complete their PARASITES ACCORDING TO PATHOLOGIC development and to propagate their species. Obligate LOCATIONS parasites such as tapeworms depend entirely upon Spurious/Coprozoic parasite their host for existence. Accidental/ Incidental parasite passes digestive tract of humans without infecting them establishes itself in the host in which it does not A spurious parasite is a free-living organism that ordinarily live. passes through the digestive tract without infecting the ✓ Parasites of animals that accidentally acquired host. by humans Occasional/Periodic Coprophilic parasite seeks its host intermittently to obtain nourishment. parasite multiply in fecal matter outside the human ✓ Only visit the host during the feeding time body Saprophytes Hematozoic parasite live in organic substances in state of lives inside the red blood cells decomposition. Cytozoic parasite Erratic lives inside the cells or tissues those that live in an organ different from the one it Coelozoic parasite usually parasitize. ✓ Parasite considered Erratic when it is found in lives in body cavities an organ which is not its usual habitat ✓ Ex: Habitat of an organism is on small intestine Enterozoic parasite but isolated on lungs – considered Erratic Parasite lives in the intestine Zoonotic TYPES OF HOST a. Definitive host animal parasites, non-human parasites that may cause human infections. final host, harbours the adult and sexually mature form PARASITES ACCORDING TO THE DURATION OF PARASITISM A definitive or final host is one in which the parasite attains sexual maturity. In taeniasis, for example, Temporary parasites humans are considered the definitive host. free living during part of existence, larval stage has b. Intermediate host a different host from its adult stage. harbours the larvae or asexual stage of the parasite ✓ Intermediate host (pinaglilipatan) An intermediate host harbors the asexual or larval A temporary parasite lives on the host only for a short stage of the parasite. Pigs or cattle serve as period of time. intermediate hosts of Taenia spp., while snails are hosts of Schistosoma spp. If there is more than one intermediate host, these can be classified as first and second intermediate hosts. Page 2 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 2: INTRODUCTION TO PARASITOLOGY c. Reservoir host The incubation period is the period between infection animal that harbours the same parasite of man and evidence of symptoms. It is sometimes referred to ✓ additional sources of human infection as the clinical incubation period. ✓ Ex: Pigs are reservoir of Balantidium coli 6. Pre-patent period They allow the parasite’s life cycle to continue and biological incubation period, period between become additional sources of human infection. Pigs are infection and acquisition of the parasite and reservoirs of Balantidium coli, field rats of Paragonimus evidence or demonstration of infection. westermani, and cats of Brugia malayi. ✓ Deals with the demonstration of the infection through parasitic stages or morphology that are d. Paratenic host seen harbours a stage of the parasite where in no further ✓ Ex: Malaria – it takes time to develop parasitic development in parasite takes place morphology ✓ Ex: Angiostrongylus cantonensis is in larva 7. Autoinfection form when resided in the human body and will infected individual becomes his own direct source not develop into adult form. Their definitive host of infection is the house rats while humans are considered 8. Superinfection or Hyperinfection as their paratenic host. already affected individual is further infected with A paratenic host is one in which the parasite does not the same species leading to the massive infection develop further to later stages. However, the parasite with the parasite remains alive and is able to infect another susceptible 9. Co-infection host. simultaneous infection of a host by two or more parasite For example, Paragonimus metacercaria in raw wild ✓ Presence of Ascaris lumbricoides, Trichuris boar meat can pass through the intestinal wall of trichiura, and hookworms, you can acquire all humans and complete its development. In this case, the of them in soil – so pwede sila makuha ng wild boar serves as a paratenic host transferring the sabay sabay infective stage to humans. OTHER SOURCES OF EXPOSURE TO INFECTION Paratenic hosts are important because they widen the parasite distribution and bridge the ecological gap A. Contaminated soil and water between the definitive and intermediate hosts. lack of sanitary toilets and use of night soil SOURCES OF EXPOSURE TO INFECTION (fertilizers – feces of human) Soil: Ascaris lumbricoides, Trichuris trichiura, 1. Pathogens Hookworm, Strongyloides stercoralis can be animal parasites that are harmful and Water: Amoeba, Flagellates, Blood flukes frequently cause mechanical injury to their host ✓ Pathogenic: can cause diseases The most common sources are contaminated soil and ✓ Non-pathogenic: cannot cause diseases water. 2. Carrier Lack of sanitary toilets and the use of night soil or harbours a particular pathogen without manifesting human excreta as fertilizer allow the eggs to come in signs and symptoms contact with the soil and favor the development of ✓ Asymptomatic carrier Ascaris lumbricoides, Trichuris trichiura, Strongyloides 3. Exposure stercoralis, and hookworm. process of inoculating an infective agent 4. Infection Water may be contaminated with cysts of amebae or establishment of the infective agent in the host flagellates, as well as cercariae of Schistosoma 5. Incubation period period between infection and evidence of symptoms ✓ Period between infection and evidence of symptoms ✓ Deals with signs and symptoms ✓ Ex: COVID19 – Day 1 is your incubation period Page 3 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 2: INTRODUCTION TO PARASITOLOGY B. Food containing immature infective stage of TYPES OF VECTORS parasite Vector: responsible for transmitting the parasite from consumption of undercooked or raw freshwater fish, one host to another. crab, snail, beef and pork the parasite is seen inside Another possible source of infection is food, which may the body of this organism contain the infective stage of the parasite, as and the parasite needs this organism for its exemplified by a number of trematode and cestode development. infections. They are part of the life cycle of the parasite Consumption of undercooked or raw freshwater fish can Ex: mosquitoes, tsetse flies result in several intestinal and liver fluke infections. a. Biological vector Biological vectors, (e.g., Raw crabs are considered a delicacy in areas where mosquitoes and biting flies), paragonimiasis is endemic, while raw Bullastra snails acquire pathogenic agents in are associated with Artyfechinostomum malayanum the act of blood-feeding. These infection. agents undergo multiplication, propagation, and development C. Arthropods, blood sucking insects and other wild inside the arthropod’s body. or domesticated animals responsible only for Mosquitoes (Filaria and Malaria) transporting the parasite, Triatoma bugs (Trypanosoma cruzi) the parasite is only seen on Sandflies (Leishmania) the surface of this organism Cats, dogs and house rats and there will be no development on the Arthropods can also transmit infection. Mosquitoes are parasite. vectors of malaria and filarial parasites. Triatoma bugs Ex: cockroaches, house flies are carriers of Trypanosoma cruzi causing Chagas b. Mechanical vector disease. Sand flies (e.g., Phlebotomus spp.) are the Mechanical vectors serve as natural vectors of all types of Leishmania. mere contaminators; the pathogens do not undergo Other animals, whether wild or domesticated, may also multiplication or development harbor parasites. Cats are direct sources of inside their bodies. Some Toxoplasma infection, while rats may be infected with vectors (e.g., fleas, beetles, crabs, and copepods) serve as Hymenolepis nana. intermediate hosts to some D. Another Person parasites. Beddings and clothing MODES OF TRANSMISSION Immediate environment he has contaminated Soil transmitted E. One’s self Arthropod/ Vector transmitted Autoinfection: self is the source of infection A biologic vector transmits the parasite only after Enterobius vermicularis, Hymenolepis nana, and the latter has completed its development within the Strongyloides stercoralis host. Food-borne Autoinfection where the infected person himself is the Water-borne source of infection is seen in the life cycles of Capillaria Skin penetration philippinensis, Enterobius vermicularis, Hymenolepis Congenital transmission nana, and Strongyloides stercoralis. ✓ During the pregnancy Direct contact ✓ Ex: kissing/ sexual intercourse Page 4 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 2: INTRODUCTION TO PARASITOLOGY PORTAL OF ENTRY LIFE STAGES OF A PARASITE By mouth: most common area of invasion, Ova entrance for intestinal protozoa Egg Skin penetration Larva Intranasal: inhalation of eggs Trophozoite Transplacental infection – during pregnancy Cyst Transplacental infection occurs when previously Adult non-infected hosts become infected during pregnancy. The organism multiplies in the placenta MODE OF REPRODUCTION and spreads to the fetal tissues. Sexual - there is a fertilization occuring Transmammary – during breast feeding Oviparous: "egg birth“, give birth to eggs that must Transmammary infection with Ancylostoma and develop before hatching Strongyloides, the parasites may be transmitted through mother’s milk. Insects are dioecious; the male and female must mate before eggs are produced. Insects which lay eggs are Sexual intercourse called oviparous, while those which deposit larvae are called viviparous. PORTAL OF EXIT Stool Ovoviviparous: ones that produce eggs but retain Urine them inside the female body until hatching occurs, so that "live" offspring are born Sputum Blood The sexes are separate, and eggs are usually laid in Tissue aspirates and biopsy capsules. Some are ovoviviparous. Orifice swab Discharge Larviparous/ Viviparous: being born alive without eggs NOMENCLATURE - Ex: humans Classified according to the International Code of Asexual Zoological Nomenclature Scientific name are Latinized Binary fission: division in half Generic names consist of a single word written in initial capital letter, the specific name always begins The life cycle includes repeated divisions by binary with a small letter. fission (merogony) or multiple fissions (schizogony) Names of genera and species are italicized or and spore production (sporogony) underlined when written. Parthenogenesis: unfertilized ovum develops directly into a new individual, natural form of Kingdom: Animalia asexual reproduction in which growth and Phylum: Nematoda development of embryos occur without fertilization Class: Secernentea by male sex cell Order: Ascaridida Ex: nematode (Strongyloides stercoralis) – can Family: Ascarididae fertilize its own ova without the help/benefit of male Genus: Ascaris Species: Ascaris lumbricoides Females generally reproduce by parthenogenesis. They invade the intestinal mucosa where they deposit their eggs. III. TYPES OF LIFE CYCLE IV. EPIDEMIOLOGIC MEASURES Simple or complicated Most parasitic organisms attain sexual maturity at Epidemiology: science concern with the the definitive host. propagation of the disease, study of patterns, Larval stage of parasite may pass through different distribution and occurrence of disease stages in an intermediate host. Incidence: number of new cases of infection As life cycle becomes complicated, the lesser appearing in a population in a given period of time chances are for the individual parasite to survive. − Absolute number − Ex: COVID19 incidence as of today is 12 Page 5 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 2: INTRODUCTION TO PARASITOLOGY Prevalence: usually expressed in percentage, V. PATHOPHYSIOLOGY AND SYMPTHOMOLOGY number of individuals in a population estimated to OF PARASITIC INFECTIONS be infected with a particular parasite at a certain Traumatic or physical damage time − How many in your population are infected - when parasites invade the skin and other tissues with 1 parasite causing destruction − Ex: 100 in community – half of it have parasitic infection – therefore your prevalence is 50% Cumulative prevalence: percentage of individuals in the population infected with at least one parasite Intensity of infection: number of worms per infected person (worm burden) – Direct: counting expelled worms during treatment Creeping eruption caused by hookworms - causing severe itching, blisters, red growing winding rash. – Indirect: counting helminth egg excreted in feces, expressed in egg per gram Lytic necrosis DISTRIBUTION OF DISEASES - secretory and excretory products elaborated by many parasites allow them to metabolize nutrients obtained Sporadic from the host and store these for energy production. appears only occasionally in one or at most a few members of the community Ex: Tetanus and rabies Endemic there is a steady moderate level of disease in human population Entamoeba histolytica in rectal biopsy constant presence Entamoeba histolytica secretes enzyme cysteine Ex: Malaria in Palawan – in 1 month there is usual proteinase to digest cellular materials and degrade 1 or 2 cases epithelial basement membrane facilitating tissue Epidemic invasion. Tissue reactions there is a sudden outbreak or rise of incidence in human population - cellular proliferation, white cell in filtration at the side increase of cases - above normally expected in a of the parasite population in particular area Ex: Influenza Pandemic when the disease have been disseminated in extensive area of the world worldwide - spread all over several countries and Filarial Larvae of Strongyloides stercoralis continents Ex: COVID-19, AIDS, and HIV Helminth infection – causing increase blood eosinophil counts – isolated in lungs Page 6 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 2: INTRODUCTION TO PARASITOLOGY Toxic allergic phenomena Deworming - when proteins or other metabolites of the parasites are use of anti-helminthic drugs in an individual or public introduced into the body, there is sensation to the health program. foreign substance which may produce hypersensitisation to anaphylactic shock Cure rate: usually expressed in percentage, number of previously positive subjects found to be egg-negative in examination of a stool or urine sample using a standard procedure at a set time after deworming Egg reduction rate percentage fall in egg counts after Punctuate keratitis deworming based on examination of a stool or urine sample using a standard procedure Deprivation of the host’s essential nutrients and at a set time after deworming substances: Selective treatment - the parasite competes with its host for the available supply of vitamin. individual-level deworming with selection of treatment based on a diagnosis of an infection or based on presumptive grounds Selective treatment involves assessment of the intensity of infection, or based on presumptive grounds. This strategy can be used in whole populations, or in defined risk groups. FACTORS THAT DETERMINE THE INTENSITY OF Targeted treatment PARASITIC INFECTION group-level deworming where the risk group to be Topography of locality treated (with or without prior diagnosis) may be Social condition defined by age, gender or other social Age characteristics irrespective of infection status. Hygienic measure ✓ Ex: Target treatment: Children (according to Sewage disposal age) Water supply Universal treatment TREATMENT population-level deworming in which the There are several options for treating parasitic community is treated irrespective of age, gender, infections. Many of these drugs are toxic to the host infection status or other social characteristics. and care should be exercised when selecting the ✓ No inclusion or exclusion criteria proper course of treatment. Coverage – antiparasitic medications (Chemotherapy) proportion of target population reached by an – change in diet intervention. – vitamin supplements It could be the percentage of school-age children – fluid replacement treated during a treatment day. – blood transfusion Drug resistance – bed rest genetically transmitted loss of susceptibility to a drug in a worm population that was previously sensitive to the appropriate therapeutic dose. Page 7 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 2: INTRODUCTION TO PARASITOLOGY Efficacy – housing that is adequate in terms of location, quality of shelter and indoor living conditions, effect of a drug against an infective agent in deal experimental conditions and isolated form of any – facilities for personal and domestic hygiene context. – safe and healthy working conditions ✓ Does the intervention work? ✓ Is the drug working or not? Sanitation Effectiveness provision to access to adequate facilities for safe disposal of human excreta, usually combined with measure of the effect of a drug against infective access to safe drinking water agent in a particular host, living in a particular environment with specific ecological, ERADICATION AND ELIMINATION immunological, and epidemiological determinants. ✓ Does it benefit your patient? Disease eradication: ✓ Is it effective or safe? permanent reduction to zero of the worldwide Effectiveness is usually measured by means of incidence of infection caused by a specific agent, as qualitative and quantitative diagnostic tests which a result of deliberate effort. Once this is achieved, detect eggs or larvae in feces or urine after an optimal continued measures are no longer needed. time interval, which is variable for each parasite. ✓ Ex: Small pox – do not exist – once it is achieved we no longer use any measure PREVENTION AND CONTROL needed (completely erased). Morbidity control Disease elimination: avoidance of illness caused by infections, may be reduction to zero of the incidence of a specified achieved by periodically deworming individuals or disease in a defined geographical area as a result groups, known to be at risk of morbidity of deliberate effort. Continued intervention and ✓ you can give deworming surveillance are still required. ✓ Ex: Periodically deworming of farmers ✓ Disease is still there, but we do not have any new cases encountered. Information-education-communication (IEC) health education strategy that aims to encourage people to adapt and maintain healthy life practices Environmental management planning, organization, performance and monitoring of activities for the modification and/or manipulation of environmental factors or their interaction with human beings – preventing or minimizing vector and intermediate host propagation – reducing contact between humans and the infective agent Environmental sanitation intervention to reduce environmental health risk – safe disposal and hygienic management of human and animal excreta, refuse and waste water – control of vectors, intermediate host and reservoir of diseases – provision of safe drinking water and food safety Page 8 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 3: Intestinal and Extraintestinal Amoebae PROTOZOA reticulum, food vacuoles, and contractile vacuoles Proto (first), Zoa (animals) ✓ Contractile vacuoles regulate osmotic pressure A unicellular organism that performs all the between the parasite and its environment functions: reproduction, digestion, respiration, Ectoplasm: outer (non-granulated), typically excretion, etc. watery ✓ Protozoans – they are single celled organisms ✓ Homogenous and serves as an organ for having true nucleus, and considered as motility and engulfment of food by producing eukaryotic cells pseudopodia ✓ Protozoans are unicellular organisms ✓ Helps in respiration, discharging waste material and providing protective covering Protozoa – Structures for locomotion: pseudopodia, flagella, Parasitic infections are either due to the unicellular cilia, undulating membrane protozoan or the multi-cellular metazoan. Generally, protozoan parasites are provided with a nucleus or ✓ Mostly protozoans they have structures for nuclei, cytoplasm, an outer limiting membrane, and motility or structures for locomotions cellular elaborations called organelles. Among these ✓ Pseudopodia - Finger like bodies are locomotory apparatus, which include cilia, flagella, ✓ Flagella - Tail like bodies or formations and pseudopodia. There is increasing knowledge ✓ Cilia - Hair like broad bodies or formations about the presence of an apical complex found to aid ✓ Undulating membrane - also used by the organism in the penetration of target cells. protozoans as a support in their locomotion or motility Many of these protozoa require a wet environment for ✓ Mostly with protozoans, motility are present at feeding, locomotion, osmoregulation, and reproduction. trophozoite They form infective stages called cysts, which are ✓ Trophozoite as the motile form relatively resistant to environmental changes compared to the vegetative stages, called trophozoites. The – Plasma membrane: controls secretions and parasitic species are capable of multiplying within the excretions host and may be transmitted through a biological vector within which they can also multiply. – Cytostome: cell mouth Composition: – Chromatoidal bodies: storage for glycogen protein – Nucleus: usually single but may be double or Under Phylum Sarcomastigophora are two subphyla, multiple; contains one or more nucleoli or a central namely, Subphylum Mastigophora, whose organelles karyosome of locomotion are whip-like structures arising from the ectoplasm called flagella, and Subphylum Sarcodina, ✓ Usually the nucleus of protozoans can be one, whose organelles of locomotion are hyaline foot-like two, or more extrusions from the ectoplasm called pseudopodia. ✓ Karyosome – a DNA containing body (can be seen on the nucleus of protozoans) which is Subphylum Mastigophora includes the atrial situated peripherally or centrally (can be seen flagellates and hemoflagellates, namely, Giardia, at the side or at the center of nucleus) Chilomastix, Trichomonas, Dientamoeba, ✓ Most commonly the karyosomes they are found Trypanosoma, and Leishmania. Subphylum in the intestinal Amoeba Sarcodina includes the amebae, namely, Entamoeba, ✓ Karyosomes also use in order for us to Endolimax, Iodamoeba, Acanthamoeba, and Naegleria. differentiate Entamoeba histolytica and Phylum Ciliophora, whose species have organelles of Entamoeba coli locomotion that are hair-like projections from the ✓ For Entamoeba histolytica: The karyosomes ectoplasm called cilia, which includes only one parasite is place at center of medical and public health interest, Balantidium coli. ✓ For Entamoeba coli: The karyosomes is place at the side or periphery of the nucleus – Cytoplasm Endoplasm: inner (often granulated), dense part ✓ Granulated because it shows number of structures such as golgi bodies, endoplasmic Page 1  CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 3: Intestinal and Extraintestinal Amoebae Classification of Protozoan Parasites Subphylum Mastigophora Phylum Sarcomastigophora ✓ Other: Subphylum Mastigophora – from the word Entamoeba dispar Mastics which means whip or flagellum Acathamoeba Entamoeba ✓ Subphylum Mastigophora locomotory organ: Endolimax nana Flagella Subphylum gingivalis ✓ It includes those protozoa which possessed the Sarcodina Entamoeba coli Entamoeba whip like flagella such as atrial and reproductive Iodamoeba histolytica organ flagellates, as well as blood and tissue butschlii flagellates Naegleria fowleri Phylum Ciliophora Chilomastix mesnili Dientamoeba fragilis ✓ Phylum Ciliophora – this protozoa is motile by the Giardia lamblia means of cilia, covering the entire body surface of Subphylum Trichomonas Trichomonas parasites Mastigophora hominis vaginalis Trichomonas ✓ Balantidium coli – the only human parasites in this Trichomonas group – the only one associated with phylum vaginalis tenax ciliophora which causes human infection Leishmania Phylum Apicomplexa braziliensis Leishmania donovani ✓ Phylum Apicomplexa – formerly known as Leishmania tropica Trypanosoma Sporozoa Trypanosoma cruzi ✓ Members of this group they posses (at some stage brucei complex of their life cycle) a structure called apical complex ✓ Apical Complex – apica complexa – serving as the Phylum Ciliophora Balantidium coli organ for attachment to the hosts ✓ This group belongs the malarial parasites, Babesia spp. plasmodium, as well as coccidians Cryptosporidium hominis Cyclospora cayetanensis Members of Phylum Apicomplexa have an apical Phylum Apicomplexa Isospora belli complex at the anterior end which consists of polar Plasmodium spp. rings, subpellicular tubules, conoid processes, Toxoplasma gondii rhoptries, and micronemes. These structures are Enterocytozon bineusi involved in the penetration and invasion of target cells. Encephalitozoon spp. All members are parasitic. Vittaforma cornea Phylum Microspora Pleistophora spp. Phylum Microspora Brachiola vesicularum Microsporidium spp. ✓ Contains many intracellular protozoans parasites which frequently cause disease in immunodeficial subjects ✓ Just like with coccidian parasites most of the Subphylum Sarcodina microspora, they can only infect those ✓ Subphylum Sarcodina – the intestinal and extra immunocompromised patients intestinal amoeba ✓ Rarely they may cause illness in immunocompetent ✓ Sarcodina – came from the word Sarcos which patients, but then again microspora can only infect means flesh or body those patient that is immunodeficient ✓ Includes parasites which have no permanent 2 stages that is commonly encountered in potozoans locomotory organ but they move about with the aid are the CYSTS AND TROPHOZOITES of the temporary prolongations of the body called as the Pseudopodia ✓ Trophozoite – they divide by binary fission ✓ Sarcodina organ for locomotion: Pseudopodia ✓ Examples of parasites: Amoeba ✓ Extraintestinal amoeba or free-living pathogenic amoeba such as Naegleria fowleri and Acanthamoeba spp. Page 2 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 3: Intestinal and Extraintestinal Amoebae Encystation Phylum Sarcomastigophora stage forming a cyst or becoming enclosed to a Subphylum Sarcodina capsule, this event takes place in the rectum of GENERAL RULES FOR AMEBAE the host as feces are dehydrated or soon after the feces have been excreted. All Entamoeba are commensal except for ✓ Trophozoite -> Cyst Entamoeba histolytica. ✓ From a trophozoite forming a cyst that is ✓ Commensalism – a kind of relationship where encystation one organism is benefitting and the other is neutral or not being harmed Encystation occurs as amebae pass through the lower ✓ Entamoeba are commensal or non- colon where colonic contents are more dehydrated. pathogenic means that they cannot cause Excystation infection, so the pathogenicity or the pathology is only associated with Entamoeba histolytica escape from cyst or envelope, produces a ✓ Generally, only Entamoeba histolytica can trophozoite from the cyst stage, and it takes place cause Amebiasis, so the presence of Amoeba in the large intestine of the host after the cyst has in any part of the body is exclusively applied to been ingested. Entamoeba histolytica ✓ Cyst -> Trophozoite With pseudopodium (false feet): finger-like ✓ From cyst becoming a trophozoite that is structures for movement excystation Undergoes ENCYSTATION except for E. ✓ Ex: you ingested the infected cyst on the food – gingivalis and Dientamoeba fragilis. when it goes to your intestine the trophozoite ✓ For these 2: They are only in trophozoite form will appear coming from the cyst because they do not undergo encystation Inhabits the large intestine except for E. gingivalis Process of Encystation and Excystation (gums – seen in the mouth) Amebiasis – presence of amoeba in any part of the body (exclusively applied to E. histolytica) Asexually multiplies through binary fission. ✓ Mode of reproduction: Binary fission ✓ Binary fission is a method of Asexual reproduction by which a single parasite divides either longitudinally or transversely into two, or more, or equal number of parasites ✓ The mitotic division of nucleus is followed by the division of cytoplasm PARTICULAR PARASITES: I. Entamoeba histolytica Morphologic Forms: 1. Trophozoite: divides through “binary fission”, capable of encystation (overpopulation, pH change, ✓ For the mature trophozoites: they can divide by food supply, availability of oxygen) binary fission producing young trophozoites ✓ Capable of developing into a cyst ✓ And those trophozoite can undergo encystation to ✓ Factors that can trigger your encystation: produce the cysts ✓ Overpopulation ✓ Binary fission –> after binary fission it will be divided ✓ The trophozoites in your intestine – there is into 2 (young trophozoites) –> those trophozoites a pH change – when the environment is can developed to become a cysts –> and in the becoming acidic (pH becomes acidic) process of excystation, so there is an escape in the ✓ Lack of food supply cyst or enveloped (then lalabas na jan ung mga ✓ Lack of availability of the oxygen trophozoites). 2. Precyst: contains large glycogen vacuole and two chromatid bars and then secretes a highly retractile cyst wall around it and becomes cyst. Page 3 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 3: Intestinal and Extraintestinal Amoebae ✓The trophozoite undergoes encystation in the Trophozoite intestinal lumen ✓ And encystation does not occurs in the tissues ✓ Usually feeds the RBC nor in the feces outside the body ✓ Cytoplasm would be the RBC concerning the ✓ Remember: in Entamoeba histolytica, Entamoeba histolytica encystation only happens inside the body ✓ The reason why we need to test asap the 3. Cyst: with protective thick cell wall (hyaline), trophozoite, or watery, or diarrheic samples within capable of excystation 30 mins, because most likely the stages that you ✓ Cyst is capable of becoming trophozoite will see in the watery, soft, or semi-form stool will be through the excystation process trophozoite, and they are fragile and easily ✓ This is the reason why our cyst can survive, disintegrated somehow the acidic environment of GIT ✓ Test should be done within 30 mins if the samples because of the protective thick cell wall which is are watery or diarrheic made up of hyaline Cyst ✓ Ex: We have acid inside our body such as hydrochloric acid ✓ No RBC inclusions inside 4. Metacyst: liberated quadrinucleate amoeba during ✓ Resistant in pH because of the protective thick cell excystation wall which is made up of hyaline ✓ Quadrinucleate – contains 4 nucleus Take note: All species have the following stages: trophozoite, precyst, cyst, and metacystic trophozoite; with the ✓ Entamoeba histolytica have a similar appearance to exception of Entamoeba gingivalis, which has no cyst the other parasites under the microscope stage, and does not inhabit the intestines. Humans are ✓ So it is a challenge in clinical parasitology infected by commensal intestinal amebae through to identify the amoeba because mostly they ingestion of viable cysts in food or water. Cysts pass are just the same morphologically speaking through the acidic stomach and remain viable because ✓ There is no difference among Entamoeba of protective cyst walls. Excystation occurs in the moshkovskii, Entamoeba dispar, and alkaline environment of the lower small intestines. Entamoeba histolytica Metacystic trophozoites colonize the large intestines ✓ Just by using microscopy you cannot and live on the mucus coat covering the intestinal differentiate the 3 mucosa ✓ But they can be differentiated by other tests, so more on molecular and serological testing Infective stage: mature quadrinucleate cyst passed in ✓ Ex: We can use the isoenzyme analysis, feces polymerase chain reaction, and MOT: ingestion of contaminated food and/or water with monoclonal antibody typing – these 3 E. histolytica cyst tests can differentiate Entamoeba histolytica from other species of amoeba ✓ Remember the infective stage is the Entamoeba histolytica cyst OTHER MOT for Entamoeba histolytica: ✓ Which means if the trophozoite is the one you ✓ Other modes of transmission aside from fecal oral ingested then it will not initiate the infection, route for Entamoeba histolytica, can be venereal because its not our infective stage transmission ✓ You need to ingested the infective stage for the ✓ Venereal transmission – sexual transmission infection to occur ✓ Ex: Syphilis DIFFERENCES OF TROPHOZOITE AND CYST ✓ Can be venereal transmission with E. histolytica through fecal oral contact TROPHOZOITE CYST ✓ Ex: Anal penetration + Fellatio (sinubo), Vegetative and you can get the infection by doing this thru Non-motile, non- motile stage sexual transmission feeding stage (feeding stage) ✓ There can be direct colonic inoculation through Found in soft to Found in fresh contaminated enema equipment formed stool watery, soft or semi- ✓ Enema equipment – a procedure in which Resistant to acidic formed stool uses enema equipment that have a liquid pH Fragile or gas inside, and it is injected in the rectum, typically to expel the contents of enema equipment Page 4 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 3: Intestinal and Extraintestinal Amoebae ✓ Ex: You used the same enema equipment Noninvasive colonization from the patient without disinfecting it ✓ Located in small or large intestine Life cycle of E. histolytica Intestinal disease ✓ Can disseminated on intestine Extraintestinal disease ✓ Can spread to other parts of the body as in the extraintestinal disease Morphologic comparison between E. histolytica and E. coli - these 2 species are commonly encountered in the laboratory A. Trophozoite Point of E. histolytica E. coli differentiation Sluggish Movement Unidirectional Non-progressive Progressive Non-directional Shape of Remember these three in life cycle: Finger-like Blunted pseudopodia ✓ Mode of transmission – how we get the parasites Manner or One at a time/ Several at a ✓ Infected stage – the parasite stage that can initiate release of explosive time the infection pseudopodia ✓ Diagnostic stage – stage of parasite where we can Uninucleated Uninucleated (central see it in the samples submitted in the laboratory (eccentric Nucleus karyosome) karyosome) Other: - whether - dulo or gilid trophozoite or cyst ✓ Intermediate host RBC ✓ Definitive host - when you Bacteria ✓ In other life cycle we have intermediate Inclusions ingested RBC you Yeast host, and then the definitive host of parasite can have E. Debris histolytica In the life cycle of Entamoeba histolytica: Dirty looking Cytoplasm Clean looking - because of its ✓ Only have 1 host – means that E. histolytica is inclusions obligatory Bigger Smaller Size - 12-60 um - 15-50 um As the cyst wall is resistant to the action of the B. Cyst gastric juice, if you have already ingested the No. of nuclei Quadrinucleate More than 4 mature cyst Sausage ✓ The cyst will pass through stomach it will damage Rod Broomstick Chromatoidal Cigar-shaped Splinter-like and enter the small intestine bar - ends will be - pointed ends 2 STAGES IN THE LIFE CYCLE OF ENTAMOEBA rounded HISTOLYTICA Nuclear Thin Thick membrane - 10-15 um - 10-35 um 1. Infective Stage ✓ Infective Cyst – that is quadrunucleate – means it contains 4 nucleus ✓ Resistant to gastric acidity ✓ Invasive trophozoite form ✓ Can invade to other parts of the body 2. Diagnostic Stage Page 5 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 3: Intestinal and Extraintestinal Amoebae Trophozoite: Pathogenesis (Disease associated with E. histolytica) ✓ If there are ingested RBCs that is for E. Symptoms histolytica ✓ Ingested debris, vacuoles or bacteria for E. Gradual onset of abdominal pain coli Diarrhea (with or without blood and mucus) In children: bloody diarrhea, fever and abdominal Cyst: pain ✓ Quadrinucleate or 4 nucleus for E. Abscess formation -> Amoebic liver abscess histolytica ✓ E. histolytica can cause intestinal and ✓ More than 4 is for E. coli extraintestinal amebiasis ✓ Incubation period is highly variable, so in an Chromatoidal bars: average it ranges from 4 days to 4 months ✓ E. histolytica – rounded ends ✓ and Amebiasis can present in different ✓ E. coli – pointed or splinter ends forms and degree of severity, depending on the organ affected and the extent of the Check for the position of Karyosome: damage cause ✓ Centrally located for E. histolytica Pathology (Intestinal amebiasis) ✓ Eccentrically located for E. coli Amoebic dysentery vs. Bacillary Dysentery TROPHOZOITE ✓ Typical manifestation of the intestinal Amebiasis is Entamoeba histolytica Entamoeba coli the Amoebic dysentery ✓ Mostly diarrhea or pagtatae, may resemble the bacillary dysentery which can be differentiated on clinical and laboratory drugs ✓ There are bacteria that can cause diarrhea particularly Enterobacteriaceae ✓ Intestinal Amebiasis – does not always result in dysentery, but quite often there may be only diarrhea or big abdominal symptoms properly called as uncomfortable belly or the growling abdomen ✓ Extraintestinal infection – it can cause abscess formation or the Amebic liver abscess (liver is infected) CYST Presence of Charcot-Leyden crystals found microscopically in the stool in cases of amoebic Entamoeba histolytica Entamoeba coli dysentery. ✓ It is Amoebic dysentery since eosinophils are involved ✓ When you see charcot leyden crystals most probably it is parasitic in nature Chromatoidal bar of E. histolytica which is sausage or Bacteria that can cause Bacillary Dysentery cigar shape with rounded ends (Enterobacteriaceae) Acute amebic colitis should be differentiated from bacillary dysentery of the following etiology: Shigella, Salmonella, Campylobacter, Yersinia, and enteroinvasive Escherichia coli Page 6  CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 3: Intestinal and Extraintestinal Amoebae HOW CAN WE DIFFERENTIATE PARASITIC invasion and evasion of the host immune INFECTION FROM BACTERIAL INFECTION? response 1. Galactose-inhibitable adherence lectin (Gal (PARAMETERS TO COMPARE THE TWO) Lectin): receptor mediated adherence of amoeba to target cells Amoebic Bacillary 2. Amoeba ionophore: cell lysis and tissue invasion dysentery dysentery 3. Cystein proteinase: most important, tissue Onset Gradual Acute invading factor No significant Fever and Signs/ Symptoms fever or usually Amoeboma vomiting vomiting Offensive, Odor of feces Odorless Fishy odor Often watery Blood and mucus (+) and bloody Flask shaped ulceration of E. histolytica pH Acidic Alkaline Numerous ✓ Amoeboma – mass like lesion with abdominal - because pain in history of dysentery Pus cell/ PMN/ neutrophil are Few ✓ Can be mistaken for carcinoma or Neutrophils higher in malignant tumors bacterial infection ✓ Benign Cellular exudates Scant Massive ✓ Mostly nagkakaroon is mga na infect Pyknotic ng E. histolytica before Numerous Few residues Extraintestinal amoebiasis Charcot Leyden Present Absent crystals Through the portal vein (liver), trophozoite reach Present other parts of the body (liver, brain, lungs and - when you see kidneys). amoeba, it Pathogenic Amoebic hepatitis means Absent amoeba ✓ This acute hepatic involvement diagnostic siya with Amoebic may be due to the repeated dysentery invasion by amoeba from an active Numerous colonic infection or to toxic - because of substances from the colon Bacteria Few reaching the liver bacterial infection ✓ Amoeba goes to liver because of Present toxic substances or it does have - because many population on the colon or in Macrophages Absent bacteria is the intestines that is why they are present invading the surrounding organs Amoebic liver abscess Pathology ✓ Most common extraintestinal form of Amebiasis Common associated disease: Intestinal amebiasis, ✓ Cardinal signs: amebic colitis, amebic dysentery, extraintestinal ✓ experiencing fever amebiasis ✓ right upper quadrant pain – because liver is located/situated there in our Can cause ulceration “flask-shaped ulcer” in the body intestines (cecum, ascending colon and sigmoid) ✓ central abscess that contains a thick Pathogenic determinants / Virulence factors of E. chocolate pus or brown pus, or Histolytica: anchovy sauce pus – which is liquefied necrotic liver tissue (parang nana on ✓ Virulence factor – these are molecules produced the liver) by microorganisms that can be bacteria, viruses, Amoebic appendicitis and peritonitis fungi, or protozoans Pulmonary amoebiasis – on the lungs ✓ It can add to the effectiveness to achieve Cerebral amoebiasis – on the brain the attachment to the cells immune Splenic abscess Page 7 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 3: Intestinal and Extraintestinal Amoebae ✓ When these goes to other part of the Entamoeba spp. stain blue body it is considered as Metastatic saline + methylene blue - differentiating them from Amoebiasis WBC ✓ Involvement of distant organs by the nucleus of E. histolytica can hematogenous spread or thru be observe lymphatics - can be observed nucleus ✓ So abscess in the kidney, brain, saline + iodine and karyosomes to spleen, or adrenals have been noticed differentiate E. Histolytica for your metastatic amebiasis from the non-pathogenic ✓ And abscess in brain leads to severe amoeba destruction of brain tissue and it is fatal 2. Concentration Techniques Cutaneous amoebiasis Formalin Ether/ Ethyl Acetate Concentration ✓ It occurs by direct extension around Technique (FECT) Merthiolate Iodine Formalin anus, discharging anuses from Concentration (MIFC) amoebic abscesses ✓ Like infections or low infectivity ✓ Extensive gangrenous destruction of 3. Culture skin occurs, and the lesion may be more sensitive than stool microscopy but not mistaken for condyloma routinely available (Ex: Robinson’s and Inoki ✓ Trophozoites invades the erectile medium, Boeck and Drbohlav media, NIH polygenic tissue media, Craig’s medium and Nelson’s medium) Genitourinary amoebiasis ✓ matagal ang incubation days ✓ Ex: In the glands of the penis, that is ✓ for research purposes you can used this penal amoebiasis which is acquired ✓ but if the result is needed right away then thru anal intercourse use direct fecal smear ✓ Can also be seen on females, in vulva, 4. Serologic Testing vagina, or cervix that is spread from ELISA, CIE, AGD, IHAT and IFAT perineum ✓ Enzyme linked immunosorbent assay Asymptomatic carriers: cysts becomes unnoticed, ✓ Counter immunoelectrophoresis ameba reproduce but infected individual shows no ✓ Agar gel diffusion clinical symptoms. ✓ Indirect Haemmagglutination – gold standard test for E. histolytica Diagnostic Stage: identification of the cyst or ✓ Indirect fluorescent antibody test – gold trophozoite standard test for E. histolytica 5. Molecular Testing Sample for ID: stool (examined within 30 minutes from collection) PCR – polymerase chain reaction Radiologic test: ✓ Ultrasound, CT scan, MRI ✓ They can detect amoebic liver abscess (early detection) Treatment for E. histolytica To cure invasive disease at both intestinal and extraintestinal site and to eliminate passage of cyst Laboratory Diagnosis (to identify E. histolytica) from intestinal lumen we are using primarily the microscopic detection of Metronidazole: drug of choice for invasive amebiasis disease and trophozoite in the stool specimen (Tinidazole and secnidazole are also effective) (Standard method of parasitological diagnosis) 1. Direct Fecal Smear Diloxanide furoate: drug of choice for asymptomatic cyst passers trophozoite motility saline solution - can detect E. Histolytica Percutaneous drainage of the liver abscess: - NSS with ingested RBC Patients who do not respond to metronidazole and need - charcot leyden crystals prompt relief of severe pain Page 8 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 3: Intestinal and Extraintestinal Amoebae ✓ Patient is not responding to treatment anymore 2. Entamoeba dispar the abscess need to be drained to relieved the pain Morphologically similar to E. histolytica, but with different DNA and RNA. Prevention and Control for E. histolytica ✓ They can be differentiated by isoenzyme analysis, polymerase chain reaction Proper hygiene – wash hands Provision for sanitary disposal of human feces 3. Entamoeba hartmanni Improve access to clean and safe drinking water Similar to E. histolytica except much smaller and no Good food preparation practices RBC inclusions Avoid using “night soil” “small-race E. histolytica” Food handler should be examined for cyst carriage ✓ Similar to E. Histolytica in morphology but in Health education and promotion size E. Hartmanni is smaller Non-Pathogenic species important to know to avoid unnecessary treatment for patients Do not contain or ingested RBC Only debris, bacteria, yeast are inside cytoplasm 1. Entamoeba coli Harmless inhabitant of the colon (commensal) Cysts: Size (10 – 35 microns) larger than E. histolytica Consists of 8 nuclei (or more) with very diffuse karyosomes May become hypernucleated with 16-32 nuclei 4. Entamoeba polecki May also contain needle-like chromatoidal bodies with irregular Parasite of the pigs and monkeys (rarely infect fragmented/sharp/splintered ends humans) Trophozoites: Size (15-50 microns) ✓ Seen in animals Smaller than E. histolytica ✓ So if there is human infection it is considered Has one nucleus containing large, diffuse as accidental or incidental infection only karyosomes Entamoeba chattoni: found in apes and monkeys, Peripheral chromatin is usually dense and identical to E. polecki, identification via isoenzyme irregular analysis Cytoplasm is usually rough and contain few to many ingested debris Entamoeba polecki is an intestinal ameba of pigs and ✓ They both (cyst and trophozoites) contains monkeys that has been occasionally detected in eccentrically or peripherally situated humans, and is a probable cause of diarrhea. They are karyosomes mainly differentiated on the basis of structure and size. Trophozoites divide by binary fission. Most cyst-forming 1. Entamoeba coli amebae go through nuclear division, and then divide again after excystation in a new host. Sluggish, not progressive and Motility non-directional Short and blunt; granular; slowly Pseudopodia extruded Bacteria and other material; no Inclusions RBCs ingested Nucleus Rarely visible Nuclear Thick; lined with coarse chromatin membrane dots and bars Large; location is eccentric; Karyosome surrounded by a halo of non- staining material Page 9 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 3: Intestinal and Extraintestinal Amoebae 5. Entamoeba gingivalis 8. Iodamoeba butschlii Can be found in the mouth (gum and teeth surfaces) “iodine-cyst” because of its affinity to iodine Abundant in cases of oral diseases Large glycogen vacuole/ body which stains deeply No cyst stage, does not inhabit the intestines with iodine (iodine loving) Transmission through kissing, droplet spray, Uninucleated – resembling a “basket of flowers” sharing utensils shape ✓ Not capable of encystation so trophozoite form only Sluggishly progressive; with Motility hyaline pseudopodia ✓ Can be seen on oral area or in the mouth Bacteria scattered throughout the ✓ RBC seen in this are only because of Inclusions cytoplasm; RBCs lesions – such as open sores in your mouth are never ingested Nucleus Not visible Large; centrally located; Karyosome irregularly rounded; surrounded by a layer of small granules 6. Entamoeba moshkovskii morphologically indistinguishable from those of the disease-causing species E. histolytica and the non- pathogenic E. dispar, but differs from them biochemically and genetically. Although sporadic cases of human infection with E. moshkovskii have been reported, the organism is considered primarily a free-living amoeba. physiologically unique: osmotolerant, able to grow FREE LIVING PATHOGENIC AMOEBA at room temperature and able to survive at 0-41°C Infectious ✓ unique They are seen in the environment ✓ can survive even without host With or without the host they can survive 7. Endolimax nana Acanthamoeba spp. (Acathamoeba castellani) “Smallest amoeba” Ubiquitous, free-living ameba “Cross eyed cyst” – 4 eccentric nuclei (nucleus is With an active trophozoite stage with characteristic like a dots under microscope) prominent “thorn-like” appendages Motility Sluggish; random (acanthopodia) and resilient cyst stage Pseudopodia Blunt; hyaline Aquatic organism, can survive in contact lens Contain food vacuoles with cleaning solutions Cytoplasm ingested bacteria ✓ Can get to watery environment Karyosome Large; central or eccentric in Most common ameba of freshwater and soil location; irregular outline No flagellate state ✓ As compared to naegleria fowleri that has flagellate state MOT: Aspiration or nasal inhalation: use of contaminated swimming pools, deep well, etc. Direct invasion of the eye: contaminated saline P a g e 10 CLINICAL PARASITOLOGY PRELIM LECTURE | FIRST SEMESTER WEEK 3: Intestinal and Extraintestinal Amoebae Acanthopodia “thorn-like” appendages Laboratory diagnosis: made by demonstration of trophozoites and cysts in brain biopsy (post-mortem in most cases), culture, and immunofluorescence microscopy using monoclonal antibodies. CSF shows lymphocytic pleocytosis, slightly elevated protein levels, and normal or slightly