Worms 2 PDF

Worms 2 Round worms Helminthology HELMINTS Flat Worms Round worms Phylum Phylum Platyhelminthes...

Worms 2 Round worms Helminthology HELMINTS Flat Worms Round worms Phylum Phylum Platyhelminthes Nemathelminthes The Trematoda Nematoda class: Cestoda (Tape worms) (Flukes)  General characters Class Cestoda (tapeworms) Segmented body Shape - flattened dorso-ventrally Lack a digestive tract - nutrition is absorbed by villi of body surface. 2 stages occur in humans a. adults - intestinal b. larvae - in tissues  General characters The body is composed of three distinct regions: scolex (a head), neck and segmented strobila proglottid = sets of reproductive organs  segments Each gravid proglottid contains both male and female reproductive organs  The head has suckers, rostellum and hooklets or sucking grooves - The neck is the budding zone from which segments are formed - The strobilus consists of immature, mature and gravid proglottides They are hermaphroditic - the set of female and male reproductive organs in every mature proglottid The neck The head has suckers  Cestoda (Tape worms) Order Order Pseudophyllidea Cyclophyllidea operculum  Medically important Tapeworms species Diphyllobothrium latum Taenia solium Taenia saginata Rodentolepis nana (Hymenolepis nana) Roundworms (Nematoda) causing filariasis Dirofilaria repens Loa loa Pseudophyllidea  Diphyllobothrium latum - fish tapeworm Distribution: cosmopolitan Nothern Europe - Scandinavia, northern Russia Asia: Japan North America: Canada, USA.  Diphyllobothrium latum fish tapeworm Largest tapeworm find in humans – up to 20 m length Definitive hosts can be humans, dogs, foxes, cats, mink, bears, and seals Disease: diphyllobothriasis Location of adult: adult stage in the small intestine (rich up to 20 m long) 2 Intermediate hosts: crustacean (1st intermediate host) fish (2nd intermediate host) Infective stage: plerocercoid Mode of transmission: Ingestion raw or poorly cooked freshwater fish containing plerocercoid Diagnosis: microscopic demonstration of eggs or proglottids in stool specimens Diphyllobothrium latum fish tapeworm  operculum Diphyllobothrium latum egg procerkoid plerocerkoid koracidium copepod (crustacean) small freshwater fish Symptoms and signs of diphyllobothriasis Diphyllobothriasis is usually asymptomatic. In some cases it causes severe vitamin B12 deficiency because D. latum can absorb most of the B12 intake (44% absorption -up to 100%). In some cases it can lead to: neurological symptoms. megaloblastic anemia (caused by vitamin B12 deficiency) which can lead to subacute combined degeneration of spinal cord Diphyllobothriasis symptoms include: constipation diarrhea fatigue obstruction of the bowel stomach pain vomiting weight loss  Uterus – rosette shape Vitteline folicis Testes Mature proglottid  Prevention Cook fish properly. If you eat sashimi or sushi, freeze it first at -10 °C (or below) for two days to kill the tapeworm larvae. Do not defecate in water (rivers, lakes etc.). If the fish tapeworm larvae cannot get in touch with the intermediate hosts, they cannot infect humans.  Pseudophyllidea Cyclophyllide Diphyllobothrium latum Taenia spp. a Egg operculated, non-operculated, with a larva unembryonated (oncosphere) Oviposition individually, through uterine en masse, following rupture pore of gravid proglottid Genital pore medial lateral Cyclophyllidea  Cyclophyllidea- one intermediate host Oncosphere 1/ first stage larva, six hooks 2/ infective to intermediate host 3/ hatches when egg ingested Roberts & Janovy, 2000 Eggs Medically important types of larvae: 1. cysticercus - larva of Taenia 2. hydatid cyst - larva of Echonococcus Intermediate 3. cysticercoid – Larva of Hymenolepis host  Cyclophyllidea uterine branches Oncosphere Mature proglottide Gravid proglottide 1 – genital pore 2 - uterus 3 - ovary  Taenia saginata beef tapeworm Distribution: cosmopolitan Disease: taeniasis Location of adult: adult stage in the small intestine (4-10 m; 2000 proglottids) Intermediate host: cattle Infective stage: cysticerci Mode of transmission: Ingestion raw or poorly cooked beef containing cysticerci Diagnosis: microscopic demonstration of eggs or proglottids in stool specimens. Tapeworm eggs can be detected in the stool 2 to 3 months after the tapeworm infection is established.  Symptoms and signs of taeniasis Most people with tapeworm infections have no symptoms or mild symptoms. Patients with T. saginata taeniasis often experience more symptoms that those with T. solium because the T. saginata tapeworm is larger in size (up to 10 m) than T. solium (usually 3-8 m). Tapeworms can cause digestive problems including: abdominal pain loss of appetite weight loss upset stomach The most visible symptom of taeniasis is the active passing of proglottids (tapeworm segments) through the anus and in the feces. Taenia saginata/solium  Taenia solium Humans can serve as 2 types of hosts after eating meat with larvae (cysticerci) after accidentaly ingestion eggs of T. solium with oncosphere Humans as a definitive hosts (“human tapeworms”) Humans as an intermediate hosts adult worm in small intestine (strobila) larvae in tissues (cysticerci) relatively nonpathogenic potentially highly pathogenic  Taenia solium – pork tapeworm symptoms and signs Human – definitive host Human - intermediate host Intestinal infection: Cysticercosis Taeniasis Infective stage - egg Infective stage - cysticerci Microscopic tapeworm eggs are ingested by a human or pig due to poor hygiene. allergic reactions c Tiny larvae called oncospheres hatch in the small intestine. constipation They penetrate the intestinal wall and enter the diarrhea bloodstream. dizziness headache loss of appetite They travel to muscles or other tissue such as nausea obstruction of the bowel the liver or the brain. Lastly, oncospheres transform into cysticerci and stomach encyst. weight loss. The smallest cysticerci are 0.5–1.5 cm long About 60 % of patients with cysticercosis have cysticerci in the central nervous system which is called neurocysticercosis.  Taenia solium - cysticercosis Brain Cysticercosis (nodules) Muscles Eyes  beef tapeworm pork tapeworm Taenia saginata Taenia solium cysticerci cysticerci egg cysticerci 2. Cysticercosis 1. Taeniasis Taeniasis  Taenia saginata and Taenia solium comparison Taenia saginata T. solium Intermediate host Cattle pig Infection by the larva cysticercus bovis by the larva cysticercus celulosae or egg Disease taeniasis taeniasis and cysticercosis Number of uterine branches 15 - 35 7 - 15 Scolex unarmed armed Length above 10 m ~8m eggs are indistinguishable Hooks Unarmed Gravid proglottide scolex 7-15 uterine lateral 15-35 uterine branches T. solium T. saginata lateral branches The number of lateral branches serves as a tool for distinguishing T. solium from T. saginata  Diagnosis Taeniasis Cysticercosis Microscopy X-ray examinations stool examination - eggs, proglottides CT (Computed Tomography) scan MRI (Magnetic Resonance Imaging) scan T. saginata (15-35 lateral branches and T. solium (7-15 lateral branches and no hooks in the scolex.) 4 hooks in the scolex.) Cysticercosis in Pig's heart  Prevention and control avoid eating row, undercooked meat access to preventive chemotherapy identification and treatment of taeniasis cases health education improved sanitation improved pigs, cows husbandry anthelmintic treatment of pigs, cows improved meat inspection, and processing of meat products http://www.who.int/mediacentre/factsheets/fs376/en/  Rodentolepis (Hymenolepis) nana dwarf tapeworm H. nana is only 15 to 40 mm long. It requires only one host but can also cycle through two. Its larvae migrate only within the gut wall, and its life span is relatively short (4 to 6 wk) H. nana is more frequent in populations living in conditions of poverty and poor hygiene, particularly when fleas are present.  http://www.msdmanuals.com/professional/infectious-diseases/cestodes-tapeworms/hymenolepis-nana-dwarf-tapeworm-infection Rodentolepis (Hymenolepis) nana dwarf tapeworm H. nana has 3 modes of infection: Indirect 2-host cycle: Rodents are the primary definitive hosts, and grain beetles, fleas, or other insects feed on contaminated rodent droppings as intermediate hosts; humans can become infected by ingesting parasitized insects. Human-to-human oral-anal cycle: Eggs are passed from one human to another or recycle externally in a single host. Internal autoinfection: Eggs hatch within the gut and initiate a 2nd generation without ever exiting the host. Autoinfection can result in massive numbers of worms, which can cause nausea, vomiting, diarrhea, abdominal pain, weight loss, and nonspecific systemic symptoms. Infections are often asymptomatic, but heavy infections may cause crampy abdominal pain, diarrhea, anorexia, weight loss and pruritis ani. Diagnosis is made by finding eggs in stool samples.  Roundworms (Nematoda) Vector-Borne Disease Disease that results from an infection transmitted to humans and other animals by blood-feeding anthropods, such as mosquitoes, ticks, and fleas.  Loa loa Microfilaria Deerflies (also known as mango flies ) of the genus Chrysops. 7 mm Ash & Orihel, 1990 Diagnosis: microfilariae in blood smear (has sheath) http://www.mclno.org/labpartners/parasit/parasit-Pages/Image11.html Geographic distribution: West and Central Africa  Symptoms of loiasis Most people with loiasis do not have any symptoms Adults commonly reside in subcutaneous tissue Calabar swellings and eye worm- usually found on the arms and legs and near joints Eye worm can cause eye congestion, itching, pain, and light sensitivity People with loiasis can have itching all over the body (even when they do not have Calabar swellings), hives, muscle pains, joint pains, and tiredness Calabar swellings  Dirofilaria D. repens D. immitis  Map showing the current distribution of Dirofilaria repens in dogs and humans in Europe 2018 Capelli et. al.  First case of heterochthonous subconjunctival dirofilariasis described in Poland. Am J Trop Med Hyg. 2010;83(2):210. Wesolowska et al. A 55-year-old Polish male presented with discomfort, redness, itching, and swelling in the left eye that had begun three days before seeking medical help. Slit-lamp examination revealed an actively moving subconjunctival worm located inferotemporally. A complete, live, moving nematode was removed under local anesthesia. An 85.1-mm-long and 0.545-mm-wide immature female worm removed from the subconjunctival nodule. The infection probably occurred during a visit to Greece 8 months before the symptoms occurred. Thank you