PARA Week 5 PDF

5 tissue and blood nematodes Trichinella spiralis Common name: Muscle Worm/Trichina Worm /Garbage Worm Greatest increase in Eosinophils All stages of development, including the larval and adult stages occur within a single host habitat Adult: Small Intestine Larva: Encysted in striated muscle (skele...

5 tissue and blood nematodes Trichinella spiralis Common name: Muscle Worm/Trichina Worm /Garbage Worm Greatest increase in Eosinophils All stages of development, including the larval and adult stages occur within a single host habitat Adult: Small Intestine Larva: Encysted in striated muscle (skeletal muscle) Hosts: Final Host: Pigs and other mammals that are omnivores/carnivores Accidental Host/Dead-end Host: Man Stages: Diagnostic Stage: Encysted Larva (muscle biopsy) Infective Stage: Encysted Larva mode of transmission: Ingestion of undercooked raw meat with encysted larva adult trichinella Male: with conical papillae (aid in copulation) after copulation, male dies Female: with club-shaped uterus; viviparous/larviparous larvae life cycle Infection for man: Ingestion of undercooked larvae-containing striated muscle (pig, bear) Larvae digested out of muscle in intestine, mature to adults Adult in small intestine Viviparous female releases larvae which penetrate intestinal mucosa and disseminate into bloodstream (no egg stage) Larvae encyst in striated muscle symptoms and pathology Trichinosis, Trichiniasis, Trichinellosis Great Imitator: can mimic other diseases 1. Larva (Muscle) Larval Migration: Fever, Facial Edema, Eosinophilia Muscle pain at the site of encystations, edema (eyelid edema) Usually arms and legs Difficulty in swallowing and breathing 2. Adult (Small Intestine) Diarrhea and abdominal pain laboratory test Muscle Biopsy (DS: Encysted Larva) Immunotests prevention Man: both definitive and intermediate host Freezing destroys Trichinella spiralis larvae Thorough cooking of meats, especially from animals known to habor T. spiralis, is paramount to the eradication of this parasite. It has been determined that proper storage of these meats, AT BELOW-ZERO TEMPERATURES (i.e. -15°C for 20 days or -30°C for 6 days) will greatly decrease the viability of the organism. Furthermore, the avoidance of feeding pork scraps to hogs is also necessary to break its life cycle. treatment Removal of muscle with encysted larvae Thiabendazole & prednisone Parastrongylus cantonensis previous name: angiostrongylus cantonensis Common Name: Rat Lungworm HOSTS: NATURAL/DEFINITIVE HOST: RATS Intermediate Hosts: Molluscs, slugs, and snails Pila luzonica (Kuhol) Brotia asperata (Suso) INFECTIVE STAGE: FILARIFORM LARVA MODE OF TRANSMISSION: Ingestion of Intermediate Host by man containing infective larva Migrate to the brain and spinal cord causing Eosinophilic Meningoencephalitis ADULT Female worm: Barber’s pole appearance; looping of whitish uterus to the red digestive tract SYMPTOMS & PATHOLOGY Eosinophilia and symptoms of meningitis (CSF contains increased WBCs plus eosinophilia) LABORATORY DIAGNOSIS Increased eosinophil count in CSF. Dracunculus medinensis Longest nematode of man (up to 1 meter) Common Names: Guinea Worm, Fiery Serpent of the Israelites, Medina Worm, Dragon Worm, Serpent Worm Thick cuticle and a large uterus that fills the body cavity and contains rhabditoid larvae Habitat: Subcutaneous Tissue Intermediate Host: Aquatic Crustacean (Copepods) – Cyclops Mode of Transmission: Ingestion of inected copepods (usually through drinking unfiltered water containing the copepods) treatment No treatment, removal only: worms are attached to a stick and slowly retracted from the host by gradual turning of the stick and removal of the worm. life cycle Intermediate host is aquatic crustacean (copepods) – Cyclops Infection: Accidental ingestion of crustacean with larva Larva digested free in the intestine, penetrates wall, and develops in body cavity or connective tissues Gravid female migrates to subcutaneous tissues and causes ulcer Ulcer, or contact with water, releases larvae 5 blood nematodes (filariae) BLOOD NEMATODES Adult worms live in tissue or the lymphatic system and produce larvae known as microfilariae (detected in the blood) Microfilariae may exhibit periodicity (parasites are present in the bloodstream during a specific time period) Diurnal occurring during the day Nocturnal occurring during the night Subperiodic timing of occurrences not clear-cut Two characteristics used in speciating the microfilariae: Distribution of nuclei within the tail Presence or absence of a sheath HABITAT: Adult: Lymphatic System subcutaneous tissue: Loa loa, Onchocerca volvulus Microfilaria: Blood except for Onchocerca HOSTS: Final Host: Man Intermediate Host: Mosquito (vector-transmitted)/Arthropods INFECTIVE STAGES: Intermediate Host: Microfilaria Final Host: Filariform Larva (L3) Mode of Transmission: Bite of an infected arthropod life cycle: Infective larvae are injected by arthropod vector upon blood meal Once inside the body, the larvae migrate to the tissues where they complete their development Fertilized adult female worms then lay live microfilariae which take up residence in the blood or dermis Microfilariae exit the body via a blood meal by the arthropod vector (IH) primary mechanism of filariasis: Lymphagiectasia: dilation of lymph vessels due to preformed saliva that enlargers to accommodate the adults Lymphagiogenesis formation of new lymph vessels by the saliva Symptoms and Pathology Elephantiasis & Hydrocoele (inflammation of the scrotum) Upper Lymphatics: Brugia malayi Lower Lymphatics: Wuchereria bancrofti Chyluria: lymphatic rupture and fluid entering the urine; milky white appearance occult filariasis With pulmonary/asthmatic symptoms No microfilariae are found in the blood Hidden deep in the body such as the lungs Laboratory Diagnosis Knott’s Technique done if there are low number of microfilaria for isolation of microfilaria 1 mL blood + 9 mL 2% formalin centrifuge ate 500 g for 1 minute stain with Giemsa Capillary Blood 2 thick smear stained with Giemsa Giemsa stained blood (method of choice) treatment Diethylcarbamazine, Ivermectin Wuchereria bancrofti Other Name: Bancroft’s Filarial Worm More prevalent; common in the Philippines Most common identified species of filarial worms that infect humans Show nocturnal periodicity (seen in large numbers in the blood between 10 PM to 4 AM) Vectors: Female mosquitoes (Aedes, Anopheles, Culex) Pathogenesis: Weingarten’s Syndrome (Pulmonary Eosinophilia) Meyers Kouwenaar Syndrome: microfilaria in spleen, liver, and lymph node that leads to hepatosplenomegaly and lymphadenopathy Brugia malayi Other Name: Malayan Filarial Worm, Brugian Filariasis Shows nocturnal periodicity Vectors: Aedes, Anopheles, Mansonia (nocturnal) Coquillettidia (subperiodic) Brugia timori nocturnal; vector (Anopheles); sheath unstained in Giemsa microfilarie tend to be longer CHARACTERISTICS Wuchereria bancrofti Brugia malayi Movement Graceful/Smooth Kinky/Stiff appearance Nuclei Not overlapping Overlapping Sheath Sheathed Sheathed No Terminal Nuclei With 2 Terminal nuclei; bulge around 2 nuclei Terminal Nuclei Onchocerca volvulus Other Names: COVOLUTED FILARIA, River Blindness Worm/Blinding Worm Vector: Simulium spp. (Black Fly/Buffalo Gnat) PATHOGENESIS: Onchocerciasis (River Blindness) second major cause of blindness in the world Lizard/Leopard skin: chronic onchocercal dermatitis) Hanging Groin SOWDA: localized onchocercal dermatitis) “Snowflake Opacities” DIAGNOSIS: Skin snips/skin biopsies Mazzoti skin test Loa loa Other Names: African Eye worm Vector: Chrysops spp. (Fruit Fly/Mango Fly/Tabanid Fly/Deer Fly) Pathogenesis: Fugitive/Calabar Swelling: localized areas of transient angioedema Encephalopathy, cardiomyopathy, nephropathy may also occur Definitive diagnosis: identification of adult worm from the eye, in tissue or in peripheral blood Sheath does not stain with Giemsa TREATMENT: SURGICAL REMOVAL OF THE WORMS Mansonella spp. Generally not associated with serious infections Vector: Culicoides spp. /Midge Mansonella streptocerca may be found in the skin; nuclei extends to tip of tail bent in the form of shepherd’s crook Mansonella perstans resides in the pericardial, pleural, peritoneal cavities; blood is the specimen of choice Mansonella ozzardi (Ozzard’s filariasis) common name: New World filaria; can also use Simulium spp. as vector Mansonella streptocerca Dirofilaria immitis Common Name: Dog Heartworm A very common filarial parasite of dogs Infective Stage: Filariform Larva (L3) Diagnostic Stage: Adult Vector: Aedes mosquito Almost all human infections come to medical attention as solitary, peripheral nodules in the lung (coin lesions) or as subcutaneous nodule In man, causes coin lesion in the lungs Gnathostoma spinigerum First intermediate host: Cyclops Second intermediate host: Fresh water fish and frog Paratenic host: Birds and humans Infective Stage: Filariform Larvae (L3) Mode of Transmission: Ingestion of undercooked fish containing the L3 larvae Syngamus laryngeus parasite of upper respiratory tract of ruminants eggs similar to Hookworm Dioctophyma renale giant kidney worm of carnivores IS: L3 Larva DS: Unembryonated Egg MOT: Ingestion of frog/fish) Thelazia callipaeda Oriental Eye Worm IS: L3 in fly mouth DS: Adults; MOT: Fly (Musca/Fannia) feeding in lacrimal secretion