BSML-2211 Clinical Parasitology PDF 2024-2025

LESSON #1: CLINICAL PARASITOLOGY BSML-2211 2nd SEMESTER | ACADEMIC YEAR: 2024-2025 | MARILOU O. HONCULADA Macroparasite PARASI...

LESSON #1: CLINICAL PARASITOLOGY BSML-2211 2nd SEMESTER | ACADEMIC YEAR: 2024-2025 | MARILOU O. HONCULADA Macroparasite PARASITOLOGY Large, multicellular and has no direct reproduction within its vertebrate host. ​ Helminthes ​ Ascaris lumbricoides (common worm; children are most affected) ON THE BASIS OF LOCATION, PARASITES MAY ALSO BE DIVIDED INTO 2 TYPES Ectoparasites ​ Organisms which live on the surface of the skin or temporarily invade the superficial tissues of the host. ​ The area of biology concerned with the ​ The infection caused by these parasites is phenomenon of dependence of one living known as INFESTATION. organism on another. ○​ Lice ​ Deals with the parasites which infect man Endoparasites (morphology, epidemiology, life cycle), the ​ Organisms that live within the body of the diseases they produce (pathogenicity), the host. response generated by him vs. them & ​ The invasion by endoparasites is known as various methods of diagnosis & prevention. INFECTION. Morphology ○​ Protozoa ​ Study of shape, structure and sizes of an ○​ Helminthes organism. ​ Identify during microscopy. Types: Epidemiology 1.​ Obligate Parasite ​ Distribution of parasites. Organisms that cannot exist w/o a host (T. ​ Found somewhere in the Philippines, but gondii); entirely dependent. could not be present in Cagayan de Oro. Passed on to the human host because of PARASITE exposure. An organism that is entirely dependent on another 2.​ Facultative Parasite organism, referred to as its HOST, for all or part of Organisms that under favorable circumstances its life cycle and metabolic requirements. may live either a parasitic or free-living existence ​ Microparasite (N. fowleri, Acanthamoeba spp. & Balamuthia ​ Macroparasite mandrillaris). Microparasite Dual existence (harmful — when they invade the Small, unicellular and multiplies within its host or harmless) vertebrate host, often inside cells. (asexual) ​ Viruses 3.​ Accidental/Incidental Parasite ​ Bacteria Organisms that attack an unusual host (E. ​ Protozoa (entamoeba histolytica) granulosus in man — infect canines). LESSON #1 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde  ​ Harbors the adult or sexual stage of a 4.​ Aberrant/Erratic Parasite parasite. ​ Organisms that attack a host where they 2. Intermediate host cannot live or develop further (Toxocara ​ This is the host in which alternates with the canis in man); Remain as larvae. definitive host and in which the larval or ​ Occurs in an unusual organ or habitat. asexual stages of a parasite are found. 5.​ Free-living ​ Some parasites require 2 intermediate hosts for completion of their life cycle; Describes the non-parasitic stages of existence ​ Harbors the larval or asexual stage of a which are lived independently of a host parasite. (Hookworms have active free-living stages in the Example: Malaria — mosquitoes: definitive host; soil). human: intermediate host Non-infective to humans until they become 3. Paratenic host infective forms in the environment (ex: soil) ​ It is a host in which the larval stage of a 6.​ Spurious/Coprozoic Parasite parasite survives but does not develop further. ​ Remains alive and is infective to the next Free-living organism that passes through the host. gastrointestinal tract w/o infecting the host. 4. Reservoir host 7.​ Transitory ​ It is a host which harbors the parasite and Larval stage is passed in a host while the adult is serves as an important source of infection to free-living. other susceptible hosts. 8.​ Permanent ​ Epidemiologically, reservoir hosts are Completes its life cycle in a host; remains on or in important in the control of parasitic diseases; the body of the host for its entire life. allows the parasite’s life cycle to continue and 9.​ Temporary serves as a source of human infection. Live on it ghost for a short period of time. ZOONOSIS 10.​ Zoonotic This term is used to describe an animal infection Primarily infects animals and may be acquired by that is naturally transmissible to humans either man. directly or indirectly via vector. 11.​ Endoparasite ​ Leishmaniasis Lives inside the body of a host; invasion is called ​ South American trypanosomiasis infection. ​ Rhodesiense trypanosomiasis 12.​ Ectoparasite ​ Japonicum schistosomiasis ​ Trichinosis Lives on body surfaces; invasion is called ​ Fascioliasis infestation. ​ Hydatid disease 13.​ Intermittent ​ Cryptosporidiosis Visits the host only during feeding time (mosquito, bed bug, flea, tick, biting fly). VECTOR An agent, usually an insect, that transmits an HOST infection from one human host to another. An organism which harbors the parasite and Mechanical/ Phoretic Vector provides the nourishment and shelter to the A vector which assists in the transfer of parasitic latter. forms between hosts but is not essential in the 1. Definitive host life cycle of the parasite. ​ This is the host in which sexual reproduction of the parasite takes place or in which the most highly developed form of a parasite occurs; LESSON #1 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde  Eradicated if there is intervention. Symbiosis Houseflies act as a mechanical vector because we ingest whatever they carry. ​ Literally means "living together"; ​ An association in which both host and Biologic vector parasite are so dependent upon each other ​ An arthropod vector in whose body the that one cannot live without the help of the infecting organism develops or multiplies other. before becoming infective to the recipient ​ Involves the living together of individual; phylogenetically different organisms (e.g., ​ Transmits a parasite only after the latter has Host and parasite). completed part of its development. Mutualism PARASITES Beneficial to both organisms. VECTORS TRANSMITTED Commensalism Mosquitoes Plasmodium spp. ​ From the Latin word "eating at the same Wuchereria bancrofti, table." Brugia malayi ​ An association in which only the parasite derives benefit without causing any injury to Biting flies Leishmania spp., the host. Trypanosoma brucei, filariae ​ Beneficial to 1 organism, neutral to the other. Kissing bugs Trypanosoma cruzi Parasitism ​ A relationship in which a parasite benefits, Ticks, cockroaches, Babesia spp. and the host provides the benefit. houseflies ​ The host gains nothing in return and always suffers from some injury. HOST-PARASITE RELATIONSHIP ​ The degree of dependence of a parasite on its host varies. Symbiotic Relationships ​ Beneficial to 1 organism. Symbiosis: When two species benefit each other by mutually increasing their chances of survival or SOURCES OF INFECTION the progress of their environment. Contaminated soil & water ​ Soil polluted with human excreta acts as a source of infection. ​ Eggs of these parasites undergo certain development in the soil (Soil-transmitted helminths). LESSON #1 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde ​ Water contaminated with human excreta may Kissing contain viable cysts. Transmitted from person-to-person by kissing or Freshwater fishes from contaminated drinking utensils. Constitute the source of D. latum and C. sinensis. Congenital Crab and crayfishes Transmitted from mother to fetus transplacentally Sources of P. westermani. (T. gondii and Plasmodium spp.). Raw or undercooked pork Inhalation Source of T. spiralis, T. solium, T. saginata Airborne eggs of E. vermicularis may be inhaled asiatica and Sarcocystis suihominis. into posterior pharynx leading to infection. Raw or undercooked beef Iatrogenic infection Source of T. saginata, T. gondii and S. hominis. ​ Malaria parasites may be transmitted by Watercress transfusion of blood from the donor with Source of F. hepatica. malaria containing asexual forms of erythrocytic schizogony Bloodsucking insects (trophozoite-induced malaria or Transmit Plasmodium spp., W. bancrofti, etc. transfusion malaria). Housefly ​ Malaria parasites may also be transmitted by Source of E. histolytica. the use of contaminated syringes and Dog needles. Source of E. granulosus and T. canis (visceral MOT PORTAL OF ENTRY larva migrans). Cat Ingestion mouth/oral cavity (most intestinal Source of T. gondii. parasites) Man Larval skin Skin Source of E. histolytica, E. vermincularis and H. penetration nana. Autoinfection Skin inoculation Skin May occur with E. vermicularis and S. (vector-borne) stercoralis leading to hyperinfection. Sexual intercourse Urogenital tract (venereal) PORTAL OF ENTRY INTO THE BODY Oral-anal intercourse Mouth/oral cavity Mouth Intranasal Nose The commonest portal of entry of parasites is oral, thru contaminated food, water, oiled fingers or Vertical transmission Transplacental fomites (Fecal-oral route). (mother to fetus) Skin Autoinfection Internal (within the Parasites penetrate the unbroken skin of intestine) or external individuals walking over fecally-contaminated (hand to mouth) soil (Hookworm, S. stercoralis) or when blood-sucking arthropods puncture the skin to feed (Plasmodium spp.) Sexual Contact ​ T. vaginalis is transmitted by sexual contact. ​ E histolytica and G. lamblia may also be transmitted by anal-oral sexual practices among male homosexuals. LESSON #1 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde  3 MAJOR GROUPS OF PARASITES ON THE 4. Inflammatory reaction BASIS OF THEIR LIFE CYCLE ​ Most of the parasites provoke cellular proliferation and infiltration at the site of 1. No intermediate host their location. ​ In many instances, the host reaction walls off the parasite by fibrous encapsulation. 5. Allergic manifestations ​ The normal secretions and excretions of the growing larvae and the products liberated from dead parasites may give rise to various allergic manifestations. ○​ Cercarial dermatitis and eosinophilia (Schistosomes) ○​ Urticaria and eosinophilia (D. 2. One intermediate host medinensis, T. spiralis) ○​ Anaphylaxis (rupture of hydatid cyst) 6. Neoplasia ​ Parasitic infection may contribute to the development of neoplastic growth. ○​ C. sinensis and Opisthorchis viverrini associated with cholangiocarcinoma ○​ S. haematobium associated with vesical carcinoma 7. Secondary infection ​ The capacity of the migrating larvae to carry bacteria and viruses from the intestine to the blood and tissues leading to secondary Two intermediate hosts infection. ○​ Examples: strongyloidiasis, trichinosis, and ascariasis. IMMUNITY IN PARASITIC INFECTIONS The protective immune response to parasitic infections has 4 arms: 1. Cytotoxic T cells PATHOGENICITY Cell-mediated immunity Refers to the capacity of the parasite to produce 2. Natural killer damage to its host. Cell-mediated immunity 1. Traumatic damage 3. Activated macrophages Causes trauma on the tissues affected. Cell-mediated immunity 2. Lytic necrosis 4. Antibody (produced by B-cells) Some parasites secrete lytic enzymes that lyses ​ Humoral immunity tissues (E. histolytica). ​ The main classes of antibodies 3. Competition for specific nutrients (immunoglobulins) produced are IgM, IgG, and IgE Competes with the host for Vitamin B12 leading to parasite-induced pernicious anemia (D. latum). LESSON #1 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde  LABORATORY DIAGNOSIS EFFECTS OF THE HOST ON THE PARASITE Can be carried out by: The genetic constitution of the host may 1.​ Demonstration of parasites profoundly influence the host-parasite 2.​ Immunodiagnosis relationship. 3.​ Molecular Biological methods 1. Racial Variations A. Demonstration of Parasites ​ A presence of Duffy blood factor increases The definitive diagnosis is made by demonstration the risk to P. vivax infection of parasites in appropriate clinical specimens: ​ Resistance to P. falciparum to individual’s w/ 1.​ Blood sickle cell trait. Useful for detecting blood-borne parasites. 2. Diet or Nutritional Status of the Host 2.​ Stool ​ High-protein diet: unfavorable for the development of many intestinal protozoa. Diagnosis of intestinal parasitic infections and ​ Carbohydrate-rich diet: favors the helminthic infections of the biliary tract in w/c development of certain tapeworms. eggs are discharged in the intestine. 3.​ Urine COMPONENTS OF PARASITIC INFECTION When the parasite localizes in the urinary tract, ​ Host the examination of urine is useful in establishing ​ Parasite the parasitological diagnosis. ​ Vector 4.​ Genital specimens ​ MOT and portals of entry Demonstration of parasites in the vaginal and ​ Portals of exit urethral discharge and in the prostatic secretions (T. vaginalis). PARASITIC LIFE CYCLE 5.​ CSF 1.​ Mode of transmission (MOT) 2.​ Infective stage (IS) 6.​ Sputum 3.​ Diagnostic stage (DS) 4.​ Host 5.​ Stages of development 7.​ Tissue biopsy and aspiration 6.​ Environment 8.​ Culture Significant when the number of parasites in the specimens is too small. 9.​ Animal Inoculation Useful in the detection of T. gondii and Babesia spp. B. Immunodiagnosis ​ Skin tests ​ Serological tests: detects antibodies (Abs) or antigens (Ags) in the patient’s serum or other clinical specimens. C. Molecular Biological Methods Includes DNA probes and polymerase chain reaction (PCR). LESSON #1 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde  PARASITE NOMENCLATURE AND CLASSIFICATION ​ Classified according to: International Code of Zoological Nomenclature. ​ Scientific Name: -​ Ascaris lumbricoides (A. lumbricoides) Genus Specie 1. Binomial System of Nomenclature Genus ​ Represent the taxon to which the species belongs. ​ 1st letter is capitalized. Specific epithet Trivial name that distinguishes the species within the genus. Both parts of the organism’s name are italicized in normal text or underlined in handwriting. 2. Parasite Classification 1. PROTOZOA — single-celled parasites Kingdom Protista 1.1 Phylum Sarcomastigophora: -​ Mastigophora (flagellates) -​ Sarcodina (amoebae) 1.2 Phylum Ciliophora: -​ Balantidium coli 1.3 Phylum Apicomplexa: -​ Sporozoans or coccidians 2. OTHER CELLULAR PARASITES Microsporidians (spore-forming) and Blastocystis spp. 3. HELMINTHS ​ Phylum Nemathelminthes — nematodes (roundworms) ​ Phylum Platyhelminthes — trematodes (flukes) and cestodes (tapeworms) 4. ARTHROPODS ​ Class Arachnida — ticks, mites, chiggers ​ Class Insecta — lice, fleas, cockroaches, bugs, beetles, flies, mosquitoes, midges ​ Class Crustacea — copepods, crabs, crayfish LESSON #1 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde  LESSON #2: INTESTINAL NEMATODES BSML-2211 2nd SEMESTER | ACADEMIC YEAR: 2024-2025 | MARILOU O. HONCULADA GENERAL CHARACTERISTICS INTESTINAL NEMATODES 1.​ Ascaris lumbricoides INTESTINAL 2.​ Enterobius vermicularis 3.​ Ancylostoma duodenale Large Intestine 4.​ Necator americanus Small Intestine (cecum and vermiform 5.​ Stronglyoides stercoralis appendix) 6.​ Trichuris trichiura 7.​ Capillaria philippinesis A. lumbricoides E. vermicularis A. duodenale T. trichiura GENERAL CHARACTERISTICS ​ Males smaller than females and have a N. americanus curved tail. ​ Unsegmented S. stercoralis ​ Length varies from a few millimeters to meters length. T. spiralis ​ Complete digestive tract (mouth to anus) C. philippinensis ​ Worldwide distribution ​ Phylum Nematoda (“threadlike”) ​ Sexes are separate (diecious) SOMATIC ​ Female nematodes: 1. Oviparous (lay eggs) Lymphatic system Body Cavity ​ A. lumbricoides ​ T. trichiura W. bancrofti Mansonella perstans ​ A. duodenale B. malayi M. ozzardi ​ N. americanus ○​ Laying eggs containing larvae Subcutaneous Conjunctiva ​ E. vermicularis tissues 2. Viviparous (give birth to larvae) Loa loa Loa loa ​ D. medinensis ​ W. bancrofti O. volvulus ​ B. malayi ​ T. spiralis D. medinensis 3. Ovo-viviparous (laying eggs containing larvae w/c are immediately hatched out) ​ S. stercoralis LESSON #2 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde  Anterior end “3 lips” ASCARIS LUMBRICOIDES ​ Common name: common roundworm/giant worm ​ Distribution: worldwide distribution, prevalent in the tropics. ​ Habitat: adult worm resides in the small intestine (jejunum). ​ Morphology: 1.​ Adult worms ○​ Large, broad, light, pinkish, whitish ○​ Body is cylindrical, tapering at the anterior end and somewhat less at the posterior end ○​ Mouth opens at the anterior end with 3 finely toothed lips ○​ Body cavity contains ASCARON (toxic fluid) 2.​ Special characteristics ○​ Produce PI3-pepsin inhibitor3, protecting the worm from digestion. Types of ova ○​ Produce phosphorylcholine w/c suppresses lymphocyte proliferation. Fertilized egg ​ Broadly oval, golden brown MALE FEMALE ​ Single cell stage when passed out with feces Measures 25-40cm in ​ 3 layers of egg shell: Measures 15-30cm in ○​ Inner non permeable, lipoidal vitelline length and 5mm in length and 3-4mm in diameter; longer and membrane diameter. stouter than males ○​ Thick transparent middle layer of glycogen membrane Posterior end is ○​ Outermost coarsely mammillated, Tail is straight and curved ventrally to conical albuminous layer form a hook. Unfertilized egg Presence of a pair of Mature females lay ​ Development: Never undergoes further copulatory spicules of eggs (nearly 200,000 development. equal size. eggs daily) ​ Content: Irregular and disorganized. ​ Size: Larger than the fertile egg. ​ Mammillation (Cortication): May be irregular or absent. LESSON #2 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde  ​ 2 shells are distinct: MALE FEMALE ○​ The external shell is rough, brown, Narrower and longer covered with little lumps (mamillated) Round/oval measures ​ The internal shell is smooth, thick and measures 90μm in 60-75μm in length and colorless length and 55μm in 4-50μm. breadth. Bile-stained and Bile-stained and brown in color. brown in color. Surrounded by a thick, transparent shell consisting of nonpermeable Small atrophied ovum innermost lipoidal and a thin shell within vitelline membrane; a an irregular coating of thick transparent albumin. middle layer and an outermost coarsely mammillated albuminoid layer. The external shell is brown and puffy, with rather jagged lumps. Floats in saturated Innermost lipoidal solution of common vitelline membrane of salt. the shell is absent. Heaviest of all the eggs thus they do not float in saturated solution of common salt. The egg is single, smooth, thick and colorless (or very pale yellow) without the external shell, presence of a single round colorless granular central mass. No mammillation outside LESSON #2 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde  PATHOGENICITY ​ Cause: Ascariasis is caused by both adult worms and migrating larvae. ​ Effects on Host: ○​ Affects the nutritional status of the host, leading to malnutrition (retardation of growth) and night blindness (Vitamin A deficiency). ○​ Causes loss of appetite and obstruction of the intestinal tract. ​ Behavior of Worms: ○​ Worms are restless wanderers. ○​ Release toxic body fluid (ascaron) leading to various allergic manifestations. LESSON #2 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde  Prophylaxis ​ Proper disposal of human feces ○​ Prevents soil contamination with infective eggs. ​ Avoidance of eating raw vegetables and salads ○​ Wash produce thoroughly to avoid ingesting eggs from contaminated soil. ​ Periodic treatment with an effective anti-helminthic ○​ Recommended for populations at high risk of infection. ​ WASHED (water, sanitation, hygiene, education, deworming) ○​ Water: Ensure access to clean water. LABORATORY DIAGNOSIS ○​ Sanitation: Promote proper sanitation practices. Demonstration of Adult Worms ○​ Hygiene: Emphasize handwashing and hygiene. Adult worms may be observed in the feces or ○​ Education: Increase awareness about expelled from the body. parasitic infections. Demonstration of Larvae ○​ Deworming: Implement mass deworming Larvae can be detected in the sputum during the programs. migration stage. Demonstration of Eggs Both fertilized and unfertilized eggs can be identified using: 1.​ Direct Fecal Smear (DFS) 2.​ Kato-Katz technique Serodiagnosis Antibody or antigen detection methods may be utilized. Eosinophilia Eosinophilia is observed during the larval invasion stage. TREATMENT ​ Pyrantel pamoate — Causes paralysis of the worms, allowing them to be expelled by peristalsis. ​ Albendazole — Inhibits glucose uptake, leading to energy depletion and death of the parasite. ​ Mebendazole — Disrupts microtubule formation in worms, impairing their nutrient absorption. ​ Piperazine citrate — Causes paralysis of the worms, enabling their expulsion. LESSON #2 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde  LESSON #3: TRICHURIS TRICHIURA (HUMAN WHIPWORM) BSML-2211 2nd SEMESTER | ACADEMIC YEAR: 2024-2025 | MARILOU O. HONCULADA ​ Shape: Barrel-shaped with protruding mucous plugs at each pole, resembling a football, lemon, or Japanese lantern. ​ Contents: Undeveloped ovum. ​ Color: Yellow to brown due to bile staining; mucous plugs are colorless. ​ Floating Ability: Floats in a saturated salt solution during flotation techniques. ​ Secretion of TT47 ○​ Facilitates the parasite's ability to embed its whip-like portion into the intestinal wall, aiding its survival and pathogenesis. ​ COMMON NAME: Whipworm ​ HABITAT: large intestine ​ ADULT WORM: ○​ Whip-shaped ○​ Anterior three-fifth is very thin and hair-like ○​ Posterior two-fifth is thick ○​ Stout resembling the handle of the whip ​ MALE: with coiled posterior end ​ FEMALE: ○​ With comma or arc-shaped posterior ○​ 3-5cm OVA Infective Stage Embryonated ova LESSON #3 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde  PATHOGENICITY ​ Rectal prolapse ​ Rectal bleeding (whipworm dysentery) with abdominal cramps, blood-streaked diarrhea and sever rectal tenesmus. ​ Iron deficiency anemia (malnutrition and blood loss) LAB DIAGNOSIS Demonstration of egg in the patient’s feces (DFS, Kato-katz, FECT). TREATMENT Oral administration of mebendazole. PROPHYLAXIS: ​ Sanitary disposal of feces ​ Avoiding consumption of raw vegetables ​ Treatment of infected persons LESSON #3 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde  LESSON #4: HOOKWORM BSML-2211 2nd SEMESTER | ACADEMIC YEAR: 2024-2025 | MARILOU O. HONCULADA Necator americanus HOOKWORMS Tropical and subtropical regions. Copulatory Bursa Ancylostoma duodenale ​ Present in the male worm for attachment with Tends to occur in cooler drier regions. the female during copulation. ​ Common Name: Old World hookworm ​ Consists of 3 lobes: 1 dorsal and 2 lateral ​ Habitat: small intestine of man, particularly in the jejunum, less often in the duodenum and rarely in the ileum. ​ Infective stage: Filariform larvae ​ Reservoir host: Dogs, cats, hogs, lions, tigers, gorillas ​ Intermediate host: none ​ Morphology: Adult worms ○​ Small, pinkish and fusiform in shape ○​ Anterior end is curved dorsally (Hookworm) ○​ Oral cavity provided with 4 hook-like teeth on ventral surface and 2 knob-like teeth on dorsal surface. ○​ Rarely seen since they remain firmly attached to the intestinal mucosa by means of well-developed mouth parts. MALE FEMALE Measures 5-11mm x Measures 9-13mm x 0.4-0.5mm 0.6mm ​ Rhabditiform larvae Posterior end ○​ Long buccal canal, small genital expanded in an Posterior end is umbrella-like fashion tapering. primordium (copulatory bursa) ○​ Usally not found in stool but may be found if there is delay in processing Genital opening opens ○​ 250-300μm long; 15-20μm wide Genital opening opens at the junction of the posteriorly with middle and posterior cloaca. thirds of the body. ​ Filariform larvae ○​ 500-600μm long ○​ Pointed tail ○​ Sheathed LESSON #4 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde  EGGS LIFE CYCLE ​ Shape: Oval or elliptical. 1.​ Host: ​ Size: Measures approximately 60 μm in ​ Humans are the only host; no length and 40 μm in width. intermediate host is required. ​ Color: Colorless (not bile-stained). 2.​ Skin Penetration: ​ Shell: Surrounded by a thin, transparent ​ Filariform larvae in contaminated soil hyaline shell. penetrate the skin of individuals walking ​ Contents: Contains a segmented ovum with barefoot. 4 blastomeres. ​ The larvae reach the subcutaneous ​ Clear Space: Notable clear space exists tissue and enter lymphatics or small between the segmented ovum and the venules, eventually entering the eggshell. circulation. ​ Buoyancy: Floats in a saturated salt solution 3.​ Migration: during flotation techniques. ​ Larvae are carried to the lungs via blood circulation. ​ They migrate up the bronchi, trachea, larynx, and epiglottis to the pharynx, where they are swallowed. 4.​ Development in the Intestine: ​ After being swallowed, the larvae undergo third molting and reach the small intestine. ​ In the small intestine, they undergo fourth molting and develop into adult worms. HOOKWORM EGG 5.​ Reproduction: ​ Six weeks after infection, male worms ​ Shape: Ovoidal. fertilize female worms. ​ Shell: Thin-shelled and colorless. ​ Female worms lay eggs, which are ​ Cell Stage: Contains a 4-8 cell stage when passed out in the feces. passed in feces. 6.​ Continuation of the Cycle: ​ Development: During delayed transit time in ​ Eggs hatch into rhabditiform larvae in the the intestine, the embryo may develop further soil under favorable conditions. inside the shell. ​ Rhabditiform larvae develop into infective ​ Differentiation: Eggs of Necator species and filariform larvae, ready to penetrate Ancylostoma species are morphologically another host's skin, repeating the cycle. similar, making differentiation difficult. LESSON #4 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde  ​ The ova are indistinguishable from A. duodenale and the life cycle, pathogenicity and diagnosis are the same. PATHOGENICITY Causes 3 types of lesions: Ancylostoma dermatitis (ground itch; dew itch) When filariform larvae enter the skin may lead to dermatitis. Creeping eruption (cutaneous larva migrans) Is a parasitic skin infection caused by hookworm larvae. Pulmonary lesions Occurs when the filariform larvae break through TREATMENT the pulmonary capillaries and enter the alveoli, they may lead to bronchitis and Mebendazole bronchopneumonia. Hypoalbuminemia Hypoalbuminemia ​ Low level of albumin due to loss of blood ​ Improved living conditions and sanitation ​ Lymph and CHON ​ Sanitary disposal of human feces ​ Wearing of shoes and gloves for personal protection LAB DIAGNOSIS ​ Direct methods: demonstration of eggs and adult worms in feces and aspiration of duodenal contents (DFS, Kato-katz, Concentration techniques, CUlture). ​ Indirect methods: through blood examination (anemia and eosinophilia) and stool exam showing (+) occult blood and Charcot-Leyden crystals. NECATOR AMERICANUS ​ A.k.a “New World Hookworm” ​ Adult worms are slightly smaller and thinner than A. duodenale. LESSON #4 (BSML-2211) Clinical Parasitology Lorin Sophia S. Itaralde