Medical Parasitology Lecture Notes PDF

MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. NEMATODE Stronglyoides Stercoralis (Threadworm) Strongyloides Stercoralis Smallest nematode of man Capable of heart-lung migration Only one host: man Habitat: Small intestine Soi...

MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. NEMATODE Stronglyoides Stercoralis (Threadworm) Strongyloides Stercoralis Smallest nematode of man Capable of heart-lung migration Only one host: man Habitat: Small intestine Soil-transmitted helminth Mode of living: faculative Rhabditiform (free-living) free living rhabditidform or parasitic filariform Measures 225um by 16um Parasitic or filariform Has an elongated esophagus with a pyriform Female -2.2mm by 0.04, colorless, posterior bulb semitransparent, with a finely striated cuticle Possess a shorter buccal capsule and a larger Has a slender tapering anterior end and a genital primordium short conical pointed tail Found in the soil The short buccal cavity has four indistinct lips Filariform larva (Infective) The long slender esophagus extends to the Measures 550um anterior fourth of the body, and the intestine is non-feeding, slender, with a distinct cleft at continuous to the subterminal anus the tip of the tail The vulva is located one-third the length of the Eggs body from the posterior end Have a clear thin shell and are similar to those The uteri contains a single file of 8-12 of hookworm except that they measure only thin-shelled, transparent, segmented ova about 50-58um by 30-34um Free-living female Measure 1mm by 0.06mm and is smaller than the parasitic female Has a muscular double-bulbed esophagus and the intestine is a straight cylindrical tube Life cycle Filariform larvae infect humans through the skin Free-living male Parasites enter the circulation, pass through Measure 0.07mm by 0.04mm, is smaller than the lungs, and migrate to the larynx where the female, and has a ventrally curved tail, two they are subsequently swallowed copulatory spicules, a gubernaculum but no Larvae develop into adults in a month’s time caudal alae while in the duodenum Parasitic male have not been reliably Females generally reproduce by identified parthernogenesis They invade the intestinal mucosa where they deposit their eggs. Egg hatch into rhabditiform larvae, migrate into the lumen and pass out in the feces. Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. Autoinfection occurs when rhabditiform larvae Complications pass down the large intestine and develop Edema, emaciation, loss of appetite, anemia, into filariform larvae lobar pneumonia, malabsorption Being the infective sage, these filariform Treatment larvae may invade the mucosa and enter the Albendazole circulation to start another parasitic life cycle without leaving the body of the host Capillaria philippinensis Capillaria philippinensis Tiny nematode residing in the small intestine of humans Male worms: range in length from 1.5 to 3.9mm Female worms: 2.3 to 5.3mm The male spicule is 230 to 300um long and has an unspined sheath Have a thin filamentous anterior end and a slightly thicker and shorter posterior end The esophagus has rows of secretory cells called stichocytes and the entire esophageal structure is called a stichosomes The anus is subterminal and the vulva in females is located at the junction of anterior Pathogenesis and clinical manifestations and middle thirds. Three phases of infection: Eggs 1. Invasion of the skin by filariform larvae Peanut shaped with striated shells and 2. Migration of larvae through the body flattened bipolar plugs 3. Penetration of the intestinal mucosa by adult Measure 36 to 45um by 20um female worms Note: 2-3 may occur simultaneously particularly in hyperinfection Larval invasion of the skin Produces erythema and pruritic elevated hemorrhagic papules Larval migration phase The lungs are destroyed causing lobar pneumonia with hemorrhage Female worms may be found in the intestinal mucosa from the pylorus to the rectum, but the greatest numbers are found in the Life Cycle duodenal and upper jejunal regions Eggs are passed in the feces and Light infection embryonated in the soil or water Does not cause intestinal symptoms They must reach the water in order to be Moderate infection ingested by small species of freshwater or Causes diarrhea alternating with constipation brackish water fish Heavy infection Eggs hatch in the intestines of the fish and Produces intractable, painless, intermittent grow into the infective area diarrhea characterized by numerous episodes of water and bloody stools Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. When the fish is eaten uncooked, the larvae 2. The water must contain the appropriate escape from the fish intestines and develop species of microcrustacean (copepod) into adult worms in human intestine 3. The water must be used for drinking Believed the parasites feed on blood due to the gut often being filled with dark brown gut material Life cycle Human drinks unfiltered water containing copepod with L3 larvae Larvae are released when copepods die. Larvae penetrate the host’s stomach and intestinal wall. They mature and reproduce Fertilized female worm migrates to surface of skin, causes a blister, and discharge larvae L1 larvae released into water from the emerging female worm. female worm begins to emerge from skin one year after injection L1 larvae consumed by a copepod Larvae undergoes two molts in the copepod Pathogenesis and clinical manifestation and become an L3 larvae Abdominal pains, gurgling stomach and diarrhea After a few weeks, there is noticeable weight loss, malaise, anorexia, vomiting, and edema Laboratory findings shows severe protein-losing enteropathy, malabsorption of fats and sugar, decreased excretion of xylose, low electrolyte levels (especially potassium) and high levels of igE Treatment Antidiarrheal and antihelminthic drug should be given Antihelminthic ○ MEBENDAZOLE ○ ALBENDAZOLE Electrolye replacement and high protein diet Diagnosis Diagnosis is made from the local blister, Tissue-dwelling Nematodes worm, or larvae 1. Dracunculus medinensis (Guinea worm) The outline of the worm under the skin Only helminthic parasite transmitted solely Some people claim to be able to feel the worm through water. moving towards the surface of the skin. Usually occurs during drought were everyone Finding calcified worm is forced to drink from the same stagnant Treatment water supplies or pay for a well Drug therapy - Metronidazole Three conditions to be met before Anti-inflammatory to help reduce swelling D.medinensis can complete its life cycle. Treatment includes the extraction of the adult 1. The skin of an infected individual must come guinea worm by rolling it a few centimeters in contact with water Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. per day usually takes weeks or months Infection is initiated by the consumption of depending on how long the worm is. raw or undercooked pork or other meat Exposing the area to cold water helps remove containing the encysted larvae. the worm faster The larvae exyst after the cysts are digested Preferably by multiple surgical incisions and penetrate into the intestinal mucosa, under local anesthesia developing to adult worms within the short Infection does not make a person immune space of 30 to 40 hours. Mating may take place as soon as the worms are mature, and larvae may be produced within 3 days after fertilization Tissue-Dwelling Nematode The larvae enter lymphatic vessels and gain 2. Trichinella spiralis access to the general circulation Common name: Muscle worm, Trichina worm They leave the capillaries in striated muscle to A parasite of carnivorous mammals penetrate through the sheaths of the muscle Common in rats and in swine fed uncooked fibers garbage Infective stage: Encysted larva found in final It may occur in humans who consume host uncooked pork Diagnostic stage: Encysted larva in striated Finals host: swine muscle tissue Dead-end: man Mode of transmission: Ingestion of raw or Habitat: Small intestine (adult form) striated uncooked pork muscles (larvae) Parasite Biology The adult worm is whitish in color and measures 1.5 to 3.5mm by 0.04 to 0.06mm Male: measures 1.5mm by 0.04mm; it has single testis located near the posterior end of the body and is joined in the mid-body by the genital tube which in turn extends back to the cloaca Famale: measures 3.5mm by 0.06mm, has a single ovary, which is situated in the posterior part of the body; has an oviduct, a seminal receptacle, a coiled uterus, a vagina and a vulva Larva: measures 80 to 120um by 5.6um at birth but reaches the size of 900-1300um by 35 Pathogenesis and Clinical Manifestation to 40m after it enters a muscle fibers Clinical Conditions In Trichinella infection, the host (humans, rats, 1. Incubation and intestinal invasion - symptoms dogs, cats, pigs, boars, foxes. walruses, or similar to those of an attack of acute food any other carnivore or omnivore) serves as poisoning, diarrhea, constipation, vomiting, both the final and intermediate host by abdominal cramps, nausea harboring both the adult and larval stages 2. Larval migration and muscle invasion - Infective larvae are usually encysted in the edema, eosinophilia, remittent fever, difficulty muscle fibers of the host in chewing, paralysis of the extremities, splenomegaly, gastric and intestinal Life cycle hemorrhage, myocardial and neurological complications, meningitis, Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. meningoencephalitis, cerebral lesions, epilepsy ○ Remittent fever meaning fever doesn't go away if the fever has 38.9 and took paracetamol, the fever will just goes down to 38 ○ Remittent fever - persistent in fever 3. Encystment and encapsulation - weakness, 1. Wucheria Bancrofti pain, brain damage, heart failure, pneumonia, Common name: Bancfoft’s filarial worm septicemia Widely distributed throughout the tropics and ○ Heart failure - causes ventricles subtropics difficult to pump Originated in southeast Asia Diagnostic Final host: Man Adult and larva may be found in stoll during Intermediate host: mosquitoes the diarrheal stage ○ Anopheles Muscle biopsy (usually of gastrocnemius) ○ Aedes Ultrasound/video graphics procedures ○ Culex Serological test/antibody-detecting test Habitat: Lower lymphatic system Treatment Giemsa stain: sheath colorless Thiabendazole 2. Brugia malayi Mebendazole Common name: Malayan’s filarial worm Albendazole Primarily seen in Southeast Asia Analgesics and antipyretics are commonly Final host: man used to control symptoms Intermediate host: mosquitoes Giemsa stain:sheath pink/purple Vector-Borne Nematodes Wucheria Bancrofti and Brugia malayi Lympathic filariasis carries with it both Filariae psychological and social stigmata, apart from Long, threadlike nematodes the serious economic consequences that it inhabit portions of the human lymphatic brings system, subcutaneous, and deep connective Wucheria bancrofti is the causative agent of tissues bancroftian filariasis while Brugia malayi The adults of all species of filariae are causes malayan filariasis parasites of vertebrate hosts. The disease cause chronic disfiguring, The adult female worms produce eggs within lymphedema, elephantiasis or hydrocoele, the uterus that eventually hatch into inflammation of the lymphatic system, acute microfilariae. fever and the bronchial0asthamatic condition Presence or absence of a sheath in the known as “tropical pulmonary eosinophilia” microfilaria stage is a basis of differentiation ○ Elephentiasis = looks like elephant leg Microfilariae, during their development, become elongate and wormlike in appearance Parasite Biology Microfilariae are generally capable of living for Adult worms are creamy white, long and a long period within the vertebrate host but filariform in shape not of developing further until ingested by Male worm: measures 2-23cm in length their intermediate host (insect vector) Female worm: measures 8-55cm in length In the insect, the microfilariae molt and grow, Microfilariae - appears as minute snake-like transforming into infective larvae (L3), which organisms (270-290um) constantly moving are deposited on the skin when the insect next among the red blood cells takes blood from a suitable host causes lymphiasis Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. Mosquitoes belonging to the genera Aedes, Culex, and Anopheles have been shown to be biologic vectors Life cycle of Filaria worms Life Cycle Adult females produce microfilariae, which gain entrance to the peripheral blood circulation where are picked up by the appropriate mosquito vector during a blood meal Microfilariae ingested by the mosquito they develop into first (L1), second (L2) and third (L3) stage larvae After 6 to 20 days of development, third stage Pathogenesis larva force their way out of the muscles, Lymphangitis and lymphadenitis causing considerable damage and migrate Lymphedema towards the mosquito’s head and proboscis Elephantiasis: disfiguring and disabling During a blood meal, larvae emerge from the condition proboscis onto the skin of another Scrotal lymphatics: preferential site for susceptible host and actively penetrate the localization of adult worm skin through the bite wound to reach the lymphatic vessels and nodes where they develop into adult worms Worms are usually localized in the lymph vessels of the lower extremities, inguinal lymph nodes, epididymis of males and labial glands of females ○ lymph node can not be amputated Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. Arthopod undergoes three stages: eggs, nymph and adult The young resembles the adult except for the smaller size and sexual immaturity Examples: Cockroaches, grasshoppers, lice and bugs Diagnostic Tests Demonstration of microfilaria in blood Diethylcarbamazine “provocative” test: stimulates microfilaria to come out to the peripheral blood Concentration techniques Serology: detection of circulating filarial antigens 2. Complete metamorphosis Radiography Arthropod undergoes four stages: eggs, larva, Ultrasonography pupa, and adult There is a great difference between the Treatment immature stages and the adults Diethylcarbamazine citrate Example: mosquitoes, flies, butterflies, moths, Ivermectin ants, bees, wasps, fleas and beetles IARTHROPODS OF MEDICAL IMPORTANCE Arthropods Arthropods Bilaterally symmetrical invertebrates with segmented bodies, jointed appendages and hard outer covering or exoskeleton Special mechanism being used by arthropods against Some demonstrate little change in their enemies: morphology throughout the different life 1. Chitinized exoskeleton (primarily a stages, while others pass through a complete nitrogenous polysaccharide which makes the metamorphosis having egg, larval, pupal and integument impervious to water adult stages 2. Appendages (may be lost and later Metamorphosis - refers to the change in form regenerated) or structure of an arthropod that occurs 3. Hairs, scales, or spines during the period of development 4. Body fluid which may be used effectively for Type of Metamorphosis their survival 1. Gradual or incomplete metamorphosis Arthropods as Direct Causes of Injury Ways by which arthropods affect humans Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. 1. Envenomation The first body segment of centipedes bears a 2. Ectoparasitism pair of modified legs which form claws having 3. Ingestant and inhalant allergens sharply pointed, horny fangs that connect to 4. Food, water, and house pests the venom glands 5. Myiasis The bite is characterized by local pain at the ○ Flying larva site of punctures, numbness, hardening of the ○ occurs in tropical region skin, formation of papules, rash, swelling and 6. Identification of myiasis-producing larvae purple patches 1. Envenomation Venoms are poisonous substances, which certain animals secrete and introduce by biting or stinging Arthropod venoms are usually poisonous when they are injected through the integument or come in contact with cut skin Allergic reaction may follow upon repeated exposure to various venomous arthropods D. Order scorpionida (scorpions) A. Order Hymenoptera (bees, wasps and ants) The abdomen is segmented with the terminal Stinging hymenopterans are divided into two five segments ending in a bulbous sac and a groups: conspicuous stinger 1. Those that kill their prey by stinging Considered dangerous since they produce 2. Those that sting only to paralyze their prey hemolytic and neurotoxic venom Formic acid - causes the paralysis The hemolytic venom causes a painful B. Order Hemiptera swelling at the site of the sting; may produce Rhodnius, Triatoma bugs - feed on blood of numbness; profuse sweating, salivation, vertebrates, including humans nausea, drowsiness Reported to inflict painful bites F. Order araneida (spiders) Complaints from patients bitten by these The first pair of appendages (chelicerae) are bugs: swelling in the area of the bite, nausea, segmented and have hollow tips, through vomiting, irritation, and pain which the venom is injected from the modified C. Order Lepidoptera salivary or poison glands The larvae of some moths and butterflies Bite by the black widow spider: slight local (caterpillars) have spines or hairs, which may swelling, chills, vomiting, cramps, delirium, contain toxins, through in some instances, spams, high fever, jaundice, contraction of leg irritation seems to be largely due to a muscle mechanical effect Upon contact, the susceptible individuals may 2. Ectoparasitism and lesions due to arthropod bites experience a burning sensation on the affected skin, which may show redness or an A. Order Diptera (Class Insecta: mosquitoes and flies inflammation Three suborders of medical importance 1. Suborder Nematocera (mosquitoes, blackflies, midges and sandflies) - Mouthparts are adapted for sucking blood - reactions to mosquito bites are associated with the trauma produced by the mechanical D. Class Chilopoda insertion of the proboscis by the mosquito; Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. saliva chemically consists of histamines and kinins B. Order Anuplara (sucking lice) 2. Suborder Barchycera (Horseflies and Wingless permanent ectoparasites of deerflies) mammals - The mouthparts of females belong to the Lice are strictly host-specific (head lice and cutting sponging type genital lice for example, are seen only in - Inflict very painful bites resulting in erythema humans) and swelling; lesions do not usually itch, but Pediculus humanus capitis (head louse) are very painful very common in the Philippines; children are most commonly affected; infestation is very much associated with warm weather, as the lice require this for further development; itching is usually the predominant symptoms due to the injection of saliva or reaction to lice feces 3. Suborder Cyclorrapha/Orthorrapha (houseflies, biting flies) - The mouthparts are of the sponging and Phthirus pubis (Genital louse; pubic/crab louse) piercing types Has a crab-like body; infestation is more - They are active at daytime and bite outdoors common in adults rather than in children Transmission usually results from intimate contact Pubic louse confines its activities to pubic hairs, but may also be found in axillary hair, eyebrows or eyelashes complaints of intense itchiness in the pubic region due to the presence of nits or eggs Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. Ticks Once the tick comes in contact with a host, the hypostome and chelicerae are inserted into the skins C. Order Siphonaptera (fleas) using their recurved teeth, a firm hold is Wingless insects; both sexes feed on blood; maintained, reinforced by a cement-like mouthparts are adapted for piercing and secretion sucking The tick can detach quickly once it is fully multiple lesions appear in areas of bites engorged without the host noticing it Tick paralysis is an acute disorder of the CNS, and is believed to bite caused by a neurotoxin secreted by the salivary glands of ticks in the process of prolonged feeding “dont squeeze them as it can do more harm” 3. Inhalant Allergens Decomposed and pulverized arthropods, cast skin, scales, hairs, spines, cocoons and webs D. Order Hemiptera (Bed bugs) permeate the air via upward air streams and Bed bugs (cimex hemipterus) inflict very convection currents and are thus considered irritating and itchy bites (erythematous) inhalant allergens of humans House dust mites (Dermatophagoides) have been implicated as a source of allergens when conducting allergy test, dust mites are also included 4. Ingestants Harmful ingestants of man: feces of cockroaches, vomitus of non-biting flies, mites and their eggs Contributory to various conditions such as enteritis hematuria ○ Enteritis - inflammation in colon 5. Food and water pests D. Order Acarina (Mites and ticks) Insects and mites are classified as pests The anterior portion is modified to form a because of the damage done on food and capitulum, made up of a centra hypostome, water and the potential risk on human upon and a paired chelicerae and palpi, which consumption function in attachment and in obtaining food Food and water adulteration/contamination Chigger (mite larva) bites cause intense are incurred during: storage, transport, pruritus and severe reactions; usually attacks preparation, processing, packaging and the legs or attaches itself to skin in areas serving where skin meets clothing, such as the edges 6. Myiasis of brassier, waistband of underwear and the Infestation or invasion of tissues or organs of tops of socks humans and animals by dipterous larvae Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. This occurs accidentally but for some species, Require a period of maturation outside the parasitism is necessary host Obligatory myiasis is the condition wherein Infective for dogs, cats, and humans larvae need a host to complete their Resemble those of Ascaris, but are larger, less development elongate, and have thinner shell and Facultative myiasis occurs when free-living albuminoid outer covering larvae become parasitic Infected dogs and cats shed Toxocara eggs in 6. Identification of myiasis-producing larvae their excreta into the environment. Once in the Identification of fly larvae is important for environment, it takes 2 to 4 weeks for prevention and control Toxocara larvae to develop inside the eggs In forensic medicine, identification of the and become infectious species and age of the larvae can help Strong protective layer establish the time of death Epidemiology Globally: toxocariasis is found in many countries, and prevalence rates can reach as high as 40% or more in parts of the world. Risk Factors Dog owner Children and adolescents under the age of 20 TOXOCARA AND ENTEROBIUS Accidentally eating dirt and play in outdoor TOXOCARA environments, such as sandboxes Toxocara More common in people living in poverty Toxocara canis is found all over the world and More prevalent in hot, humid regions where is most prevalent in areas populated in areas eggs are able to survive better in the soil populated by domesticated dogs and other Life cycle canids. Dogs are the definitive host for this Puppy usually contact it with the mother parasite before birth or from her milk Pigs, mice foxes and even birds can serve as Larvae usually mature in the puppy’s intestine paratenic hosts for toxocara canis. They live through vertical transmission in and feed on intestinal contents when in the So when the puppy is 3-4 weeks old, the worm definitive host begin to produce large number of eggs and Most of the transmission: ingestion of the could contaminate the environment through infective egg (embryonated egg) the puppy feces Causal Agents After the egg passes through the environment Toxocara canis it takes around 2-4 weeks for the infective Toxocara catis larva to develop in the eggs Toxocara malaysiensis once the person ingest one of the eggs, and General Morphology become infected with toxocariasis already It could also have paratenic host like Adults foodborne transmission Similar to Ascaris lumbricoides in appearance L3 migrate to the tissue even in the liver but only a quarter to half its size Live in the small intestine of dogs and cats Eggs Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. All wild and domestic canids More prevalent among puppies Livestock are important paratenic hosts human Cockroaches and earthworms - as paratenic/transport host Pathogenesis Hypereosinophilia ○ High level of eosinophil and triggers the iG Hepatosplenomegaly ○ Causes inflammation in the liver and spleen ○ Function arrest Chronic Pulmonary inflammation with cough and fever Neural larva Migrans ○ Epilepsy ○ Visual difficulties ○ Eosinophilic meningoencephalitis Myocarditis ○ acute heart failure Ocular larva migrans ○ diffuse unilateral subacute neuroretinitis (DUSN) Ocular toxocariasis Occurs when toxocara larva migrate to the eye. Symptoms and signs of ocular toxocariasis include vision loss, eye inflammation or damage to the retina Typically, only one eye is affected Visceral toxocariasis Occurs when toxocara larvae migrate to various body organs, such as the liver or CNS Symptoms of viscera toxocariasis include fever, fatigue, coughing, wheezing, or abdominal pain Diagnostic Tests Diagnosis of visceral larva migrans in humans is generally made on clinical ground (presence of VT or OT) Serologic tests using cultured second-stage Toxocara larvae antigen. Laparoscopy and biopsy of suspicious-looking liver nodules Treatment Host Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. Disease is self-limited (resolve spontaneously Look like a pin and white in color. with or without treatment) The female worm measures about 8 to 13mm corticosteroids (for patient who are severely in size and is fusiform in shape, symptomatic except in the ocular form) The male adult is only 2-5mm drug choice: The tail of a male is curved ○ Albendazole The anterior end tapers and is flanked on each ○ Mebendazole side by a cuticular extension called “cephalic alae”. The esophagus is slender, terminating in a prominent posterior bulb, which is called “esophageal bulb”. The cephalic alae and esophageal bulb are important in the identification of the species Prevention Take your pets to the veterinarian to prevent infection with Toxocara. Your veterinarian can recommend a testing and treatment plan for deworming Wash your hand with soap and water after playing with your pets or other animals, after outdoor activities, and before handling food or eating Teach children the importance of washing hands to prevent infection ○ happy birthday Do not allow children to play in areas that are soiled with pet or other animal feces clean your pet’s living area at least once a week. Feces should be either buried or bagged and disposed of in the trash. Wash your hands after handling pet waste. Teach children that it is dangerous to ear dirt or soil Egg Enterobius Vermicularis 50 to 60um by 25um Persimmon seed-like, colorless and Enterobius Vermicularis transparent, thick and asymmetric shell, Pinworm are one of the most common content is a larva intestinal nematodes The adult worms inhabit the cecum and colon Right after matin, the male dies, therefore the male worms are rarely seen. The female worms migrate out the anus depositing eggs on the perianal skin Humans get this infection by mouth and by autoinfection Morphology Adults Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. Risk Factors Children under 18 People who take care of infected children People who are institutionalized The prevalence can reach 50% Epidemiology More common within families with school-aged children, in primary caregivers of infected children, and in institutionalized children ingesting pinworm eggs either directly or indirectly Life cycle 1. Site of inhabitation: cecum and colon 2. Infective stage: embryonated egg 3. Infective route: mouth 4. without IH and reservoir host 5. life span of female adults: 1-2 months Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. Symptomatology About one-third of pinworm-infected persons Diagnosis are asymptomatic, the adult worms may cause Look for the worms in the perianal region 2 to slight irritation of the intestinal mucosa 3 hours after the infected person is asleep Symptoms Touch the perinatal skin with transparent tape Anal pruritus- associated with the nocturnal to collect possible pinworm eggs around the migration of the gravid females from the anus anus first thing in the morning and deposition of eggs in the perianal folds of ○ If a person is infected, the eggs on the the skins tape will be visible under a microscope restlessness, nervousness, and irritability, ○ Conducted on 3 consecutive mornings probably resulting from poor sleep - right after the infected person wakes associated with anal pruritus up and before washing In young girls, migrating of the worms may Analyzing samples from under fingernails produce vaginitis and salpingitis or under a microscope granuloma of the peritoneal cavity Diagnosis depends on the recovery of the characteristic eggs. The eggs and the female adults can be removed from the fold of the skin in the perineal regions by the use of cellophane (scotch tape) tape method, the examination should be made in the morning before the patient has washed or defecated. Treatment Since the life span of the pinworm is less than two months, the major problem is reinfection Albendazole is the drug of choice. repeated may be necessary for a radical cure. ○ 400mg PO one dose Alternate ○ Mebendazole 500mg PO one does ○ Pyrantel pamoate 125mg PO one dose Any of these drugs are given in one dose initially, and then another single dose of the same drug two weeks later. Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. the second dose of medication is to eliminate Anterior: thin, slender, with reduced possible re-infection since the first dose of esophagus medication. Poserior: thick, robust, contains intestines Prevention and reproductive organs Washing your hands with soap and water after Male worms: measure 30-45mm; slightly using toilet, changing diaper, and before shorter than the female; coiled posterior with handling food a single spicule and retractile penile sheath People who are infect should shower every Female worm: measures 35-50mm; larger than morning to help remove a large amount of the males; whip-like appearance; bluntly rounded eggs on the skin posterior end cut fingernails regularly, avoid biting the nails and scratching around the anus frequent changing of underclothes and bed linens first in the morning is a great way to prevent possible transmission of eggs in the environment and risk of reinfection Teach children the importance of washing hands to prevent infection Trichuris Trichuria (whipworm) Eggs 50-54cm by 23um football-, barrel-, lemon-shaped transparent, protuberant bipolar mucus plugs (polar prominences) Prone to desiccation 3000 to 7000 eggs are produced daily Require a period of 10 days or more outside the body to become infective Trichuris trichiura Common name: Human Whip Worm Life span: 4 to 8 years only one host: man habitat: large intestine Life cycle Infective stage: embryonated egg diagnostic stage: ova mode of transmission: ingestion of embryonated egg trichuris worms inhabit the large intestine; entire whip-like portion is deeply embedded Morphology into the intestinal wall of the cecum 3-5 cm long Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. After copulation, the female worm lays egg Kato-Katz stool examination which are passed out with feces and Zinc flotation method: extremely efficient in deposited in the soil demonstration of eggs Under favorable conditions, the eggs develop Pathogenesis and clinical manifestation and become embryonated within two to three The anterior portions of the worms, which are weeks embedded in the mucosa, cause hemorrhage, if swallowed and undergo four larval stages to which may predispose to amebic dysentery become adult worms The mucosa is hyperemic (abnormally large unlike Ascaris, there is no heart-lung amount of blood flow) and edematous migration (swelling caused by fluid trapped in tissue); enterorrhagia (bleeding within the intestinal tract) is common; there may even be rectal prolapse among the heavily infected the lumen of the appendix may be filled with worms, and consequent irritation and inflammation may lead to appendicitis or granulomas Rectal prolapse Protusion of either rectal mucosa or the entire wall of the rectum Treatment Drug of choice in the treatment of trichuriasis is ALBEDNAZOLE MEBENDAZOLE may be used as an alternative drug Necator Americanus Ancylostoma duodenale (hookworms) Diagnostic test Direct fecal smear Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. Hookworms Blood-sucking nematodes causing anemia Attach to intestinal mucosa Soil-transmitted helminths Capable of heart-lung migration Hookworm eggs Only one host: man Eggs have bluntly rounded end and a single habitat: small intestine thin transparent hyaline shell they are most commonly found in tropical and They are unsegmented oviposition and in the subtropical countries where they occur as 2-8 cell stages of the decision in fresh feces single or mixed infection Parasite biology Necator americanus adult are small, cylindircal, fusiform grayish white nematodes. Lifecycle of hookworms Females (9 to 11mm by 0.35mm) are larger Adult worms copulating while attached to the than males (5 to 9mm by 0.30mm) mucosa of the small intestines The posterior end of the male has a broad, Female worms ovipost into the intestinal membranous caudal bursa with rib-like rays, lumen and the eggs are passed out with the which are used for copulation human feces The buccal capsule has a ventral pair of In the soil, the embryo within the egg semilunar cutting plates develops rapidly and hatches after one to two the head is curved opposite to the curvature days into the rhabditiform larva. of the body which is like a hook at the anterior After 7-10 days, the larva is transformed into end the non-feeding filariform larva, which is now The adult Ancylostoma duodenale is slightly infective to humans larger than Necator americanus Filariform larvae penetrate the skin. They There are single-paired male and female enter venules and migrate to the heart and reproductive organs lungs then into the alveoli The shape of the A.duodenale adult is such The larvae then ascend to the trachea and are that the head continues in the same direction finally swallowed passing down to the small as the curvature of the body intestine The buccal capsule has two pairs of curved After another month the worms become ventral teeth sexually mature and start laying eggs Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. TIIMMUNOLOGY IMMUNOLOGY OF PARASITES Function of the Immune System To protect the body from invasion by potential pathogens Host-parasite interaction Host - provided with immune defenses: ○ Natural (nonspecific) ○ Acquired (specific) Natural (Non-specific) Immune defenses Affected by many factors that include genetics, nutritional status, hormonal balance and age among others Example: 1. Intact skin - provides effective surface protection against microbial invasion There are parasites that initiates infection through skin infection Diagnostic tests ○ Filariform larvae of hookworms and Direct fecal smear Strongyloides spp. can synthesize a concentration techniques protein that aids in the penetration Kato-Katz process Harada-Mori (recovery of larval stage) ○ Schistosoma spp. cercariae are Pathogenesis and Clinical manifestation capable of skin penetration because of The pathology of hookworm infection involes: the presence of glands in the anterior 1. The skin at the site of entry of the filariform part of the parasite larvae - lesions and localized erythema; itching is often severe and is known as 2. The acidic pH of the vaginal secretion and “ground itch” gastric juice are highly detrimental to the 2. The lung during larval migration - bronchitis surval of many microorganism pneumonitis ○ The trophozoites of Trichomonas 3. The small intestine, the habitat of the adult vaginalis are unable to survive the worms - abdominal pain, diarrhea with blood acidic environment of the vagina and mucus ○ Infective stages that are ingested like Treatment embryonated eggs of Ascaris., Taenia Drug choice: ALBENDAZOLE spp. are provided with thick egg shells MEDENDAZOLE and PYRANTEL PAMOATE that help the parasite escape the Ferrous sulfate (200mg) three times daily for acidic action severe infections until about 3 months after ○ The cystic wall of intestinal protozoa the hemoglobin value returns to normal like the Entamoeba spp and Giardia ○ for iron deficiency armenia ○ spp. are resistant to acidic pH Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. 3. Mucus secretion are also protective This response can recognize self from ○ Once the secretion envelope the non-self, has memory and is specific parasite, e.g. Giardia lamblia, the The objective of the specific response is to motility of the parasite is greatly DESTROY THE PARASITE, hence, to protect diminished, thus reducing pathology the host from the activities of the parasite on the host Antigen may be present in just one ○ Chemical components of various body developmental stages or in just one species of fluid have been found to have the parasite or in all of the stages of parasite anti-microbial action, e.g. lipase development content of breast milk was found toxic The parasitic antigens may originate from the to Giardia lamblia in vitro surface, from secretion and excretions, and from somatic tissues of the parasite 4. Human reflexes help in eliminating parasites The specific response, on the other hand, is ○ Coughing can expel erratic Adult two-fold Ascaris lumbricoides and eggs of ○ Antibody dependent or humoral Paragonimus westermani ○ Antibody independent or cell-mediated ○ Flushing action of urine can lower the number of invading Trichomonas vaginalis 5. A variety of cells in the body of the host participate in interacting with the parasites ○ Eosinophils and neutrophils are increased in cases of parasitic invasion; they are efficient in killing some parasites ○ Macrophages serve as the first line of defense against invading pathogens through phagocytosis. Intracellular protozoans such as Leishmania spp., Toxoplasma gondii, and Trypanosoma cruzi are able to invade and multiply inside macrophages 6. An array of cellular components on the skin of the host include Langerhans cells, dendritic cells, mast cells and recirculating T-lymphocytes produced by the skin-associated lymphoid tissues (SALT). There are also recirculating T-lymphocytes produced by gut-associated lymphoid tissues (GALT) in the mucosal system of the gastrointestinal tract. Acquired (specific) immune defenses The host, once infected, is exposed to the parasite antigen which in turn can stimulate the host to mount an acquired specific response against the antigen Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. ○ Example: migrating larvae of Toxocara canis are killed through cell-mediated activity 3. Th2 lymphocytes produce interleukin 4,5 and 6 that enhace the proliferation and differentiation of B-lymphocytes into plasma cells, which are responsible for antibody production ○ The antibodies then bind with specific Host-Immune Response parasite antigen (antigen classes: IgE, Immune response to parasitic infections has IgG, IgM and IgA) well-defined genetic control as reflected in the Example: helminthic infections - most outcome of infection in terms of resistance, common responses include eosinophilia and susceptibility and pathology elevated serum IgE The major histocompatability complex (MHC) Lymphatic dwelling Wucheria bancrofti and gene product regulate the T-lymphocyte Brugia malayi has more intense immune activities response as compared to lumen dwelling Ascaris lumbricoides and Trichuris trichura A specific immune response to the parasitic begins 4. IgE antibodies that bound to the mucosal when the parasitic antigens are: mast cells, eosinophils, and goblet cells can 1. Processed and presented to the T-helper mediate the eventual expulsion of adult lymphocytes, which could either be Th1 or gastrointestinal helminths Th2 (responsible for producing different IgE has also been identified on inflammatory lymphokines) cells involved in the cytocidal action on some 2. Th1 lymphocytes produce gamma interferons parasites like Schistisoma spp. referred to as and interleukin 2 which activate cytotoxic antibody dependent cell-mediated cytotoxicity lymphocytes (with CD8 surface molecules) (ADCC) and macrophages -> cell-mediated immune response (CMIR) 5. The combined activity of IgG and IgM can prevent the penetration of erthrocytes by Plasmodium spp. and Babesia spp. but they Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. are generally ineffective against Lymph nodes gastrointestinal helminth spleen Peyer's patches 6. Secretory IgA in the intestines protect against Appendix metacestode and gastrointestinal infection. Lymphatic vessels IgM with secretory IgA mediates ADCC in Bone marrow Giardia lamblia infection 2. Cells Lymphocytes ○ T-lymphocytes ○ B-lymphocytes, plasma cells ○ Natural killer lymphocytes Monocytes, macrophages Granulocytes ○ Neutrophils ○ eosinophils ○ basophils 3. Molecules Antibodies Complement Always Don’t Excrete Golden Mucus (Yao, 2024) Cytokines Interleukines Basic Immunology Interferons Definitions Immune system - cells, tissues, and molecules Two types Immune system that mediate resistance to infection Immunology - study of structure and function 1. Innate (non-adaptive) of the immune system First line of immune response Immunity - resistance of a host to pathogens Relies on mechanisms that exist before and their toxic effects infection Immune response - collective and coordinated 2. Acquired (adaptive) response to the introduction of foreign Second line of response (if innate fails) substances in an individual mediated by the Relies on mechanisms that adapt after cells and molecules of the immune system infection Role of the immune system Handled by T and B lymphocytes Defense against microbes One cell determines one antigenic Defense against the growth of tumor cells determinant ○ Kills the growth of tumor cells Homeostasis Innate immunity ○ Destruction of abnormal or dead cells Based on genetic make-up (e.g. dead red or WBC, Relies on already formed components anitgen-antibody complex) Rapid response: within minute of infection Immune system Not specific Organs ○ Same molecules/cells respond to a Cells range of pathogens Molecules Has no memory 1. Organs ○ Same response after repeated Tonsils and adenoids exposure Thymus Does not lead to clonal expansion Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. Innate immunity: mechanisms Cell-mediated immune response Mechanical barrier/surface secretion 1. T-cell ○ Skin, acidic pH in stomach cilia ○ Recognizes peptide antigen on Humoral mechanisms macrophage in association with major ○ Lysozymes, basic proteins, histocompatibility complex (MHC) complement, interferons class Cellular defense mechanism ○ Identifies molecules on cell surfaces ○ Natural killer cells neutrophils, ○ Help body distinguish self from macrophages, mast cells, basophils, non-self eosinophils 2. T cell goes into the effectors cells stage that is able to kill infected cells T-lymphocytes 2 types Helper T-lymphocytes (CD4+) Adaptive immunity: second line of response ○ CD4+ T cells activate phagocytes to Based upon resistance acquired during life kill microbes Relies on genetic events and cellular growth ○ HIV patients Responds more slowly, over few days ○ CD4+ count less than 50 Is specific Cytolytic T-lymphocytes (CD8+) ○ Each cell responds to a single epitope ○ CD8+ T cells destroy infected cells on an antigen containing microbes or microbial Has anamnestic memory proteins ○ repeated exposure leads to faster, stronger response Cell-mediated immune response leads to clonal expansion Primary response ○ Production of specific clones of Adaptive immunity: active and passive effector T cells and memory clones ○ Develops in several days ○ Does not limit the infection Secondary response ○ more pronounced, faster ○ more effective at limiting the infection Example - cytotoxic reactions against intracellular parasites, delayed hypersensitivity (e.g., Tuberculin test) and allograft rejection Adaptive immunity: mechanism ○ PPD inject molar area in the forearm Cell-mediated response (CMIR) Responsible for delayed ○ T-lymphocytes hypersensitivity reaction ○ eliminating intracellular microbes that ○ Allograft rejection transmutation survive within phagocytes or other organs coming from different infected cells individuals Humoral immune response (HIR) Humoral Immune response ○ B-lymphocytes 1. B lymphocytes recognize specific antigens ○ Mediated by antibodies ○ Proliferate and differentiate into ○ eliminate extra-cellular microbes and anti-body secreting plasma cells their toxins Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. 2. Antibodies bind to specific antigens on ○ Activates the complement microbes; destroy microbes via specific ○ used as marker of recent infection mechanisms Presence in newborn means infection 3. Some B lymphocytes evolve into the resting Single positive sample in serum or CSF state - memory cells indicates recent or active infection Used to detect early phase of infection Antibodies (immunoglobulins) IgA Belong to the gamma-globulin fraction of Monomeric in serum serum proteins Dimeric with secretory componen in the Y-shaped or T-shaped polypeptides lumen of the gastro-intestinal tract and in the ○ 2 identical heavy chains respiratory tract ○ 2 identical light chains Major function/application All immunoglobulins are not antibodies ○ neutralize microbes and toxins Five kinds of antibodies Sero-diagnosis of tuberculosis ○ IgG, IgM, IgA, IgD, IgE synthicial respiratory virus test ○ basically GAMED IgD Monomeric Major function/application ○ Present on the surface of B lymphocytes ○ functions as membrane receptor ○ role unclear Has a role in antigen stimulated lymphocytes differentiation IgE Mediate type I hypersensitivity Monomeric Major function/application ○ associated with anaphylaxis ○ plays a role in immunity to helminthic parasites IgG Serodiagnosis of infectious and non 70-75% of total immunoglobulin infectious allergies (e.g., allergic Secreted in high quantities in secondary bronchopulmonary aspergillosis, parasitic exposures disease) Cross the placenta Major function/applications Sequential IgM-IgG humoral response ○ neutralize microbes and toxins IgM ○ Opsonice antigens for phagocytosis ○ Produced as a first response to many ○ Activate the complement antigens ○ protect the newborn ○ levels remain high transiently 4-fold rise or fall indicates active infection IgG A single positive sample indicates past ○ Produced after IgM exposure ○ higher levels persist in small amounts IgM throughout life Secreted initially during primary infection ○ produced in large amount during Cannot cross the placenta secondary response Major functions/applications ○ Secreted first during primary exposure Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. persistence of antigen ○ is at high risk of infection sensitive ‘memory cells’ after Congenital (primary) immunodeficiency primary response ○ genetic abnormality defect in lymphocytes maturation Acquired (secondary) immunodeficiency ○ results from infections, nutritional deficiencies or treatments AIDS, chronic leukemia Failure of immune response Immune response helps individuals defend against ○ microbes ○ some cancers immune response can fail Summary ○ hypersensitivity reactions Innate immunity ○ immunodeficiency ○ Relies on mechanism already existing Hypersensitivity reactions before microbe infects host Cause cell damage through excessive immune ○ is the first line of defense response to antigens ○ has no memory for subsequent Hypersensitivity exposure ○ Overreaction to infectious agents ○ relies on non specific mechanism Allergy Adaptive immunity ○ Overreaction to environmental ○ Develops following entry of microbe substances into the host Autoimmunity ○ comes into action after innate ○ overreaction to self immunity fails to get rid of microbe ○ has memory to deal with subsequent Immunodeficiency exposure Loss or inadequate function of various ○ happens through specific cells components of the immune system T cells (cell mediated) Can occur in any part or state of the immune B cells (antibody mediated) system Primary immune response ○ Physical barrier, phagocytes, B ○ Short lasting lymphocytes, T lymphocytes, ○ smaller in magnitude complement, natural killer cells Secondary immune response The immuno-comprised host ○ longer in duration ○ Has an impaired function of immune ○ larger in magnitude system Transes by: Jerard Terence R. Salas MEDICAL PARASITOLOGY LECTURE Lecturer: Contreras, Anthony Joseph M. develop ‘memory cells’ following primary response Failure of immune response can result in ○ Hypersensitivity ○ immunodeficiency Transes by: Jerard Terence R. Salas