Pathology 20

• Cestodes include Taenia saginata and Taenia solium.
• Laboratory identification of parasites includes phenotypic examination, serology, and genotypic (molecular) methods.
• Prevention of parasitic diseases involves vector control, good sanitation, and good hygiene practice, which should be done in a collective manner rather than an individual basis.
• Trematodes include Schistosoma spp.
• Laboratory diagnosis of parasite diseases involves stool examination for trophozoites and cysts in the case of Giardia lamblia/intestinalis and Entamoeba histolytica, and stool or pus aspirates for direct examination in the case of Plasmodium spp, Brugia malayi, and Ascaris lumbricoides.
• Medical Parasitology and Entomology is the science that deals with parasites that live in or on other organisms called their hosts and causing injury to them.
• A parasite can be an endoparasite, which lives within another living organism, or an ectoparasite, which lives on the external surface of another living organism.
• Parasites are eukaryotic, have membrane bound nuclei, can be unicellular or multicellular, and their size ranges from tiny protozoa (1 to 2 µm) to tapeworm and bugs (measure up to 10 meters in length).
• Some parasites are non pathogenic (commensals), while others can cause diseases such as amoebiasis, malaria, filariasis, and helminth infection.
• Laboratory investigation of parasitic infection involves identifying the parasite through morphology or life cycle, and determining its infective forms.
• Terminology in medical parasitology includes obligatory parasite, which is dependent upon a host for its survival, facultative parasite, which is free-living but can become parasitic upon another organism, and accidental parasites, which infect unsuitable hosts and cannot complete their life cycle.
• Host in parasites can be definitive host, in which the adult stages of the parasite develop, intermediate host, a temporary host for the parasite, immature stage developed, or reservoir host, which can be infected with the parasite and act as a source for human infection.
• Habitat of parasite can be small intestine, large intestine, blood vessels, organs such as liver, heart, brain, lymphatic, red blood cells, muscles, or other tissues.
• Examples of parasites include Giardia lamblia (protozoa), Entamoeba histolytica (protozoa), Schistosoma spp, Taenia spp (helminth), Filaria - Brugia malayi, Plasmodium spp, Trichinella spiralis.
• Transmission of parasitic infection can occur through the mouth (faecal-oral), skin penetration of infective larval stage to skin, or other routes.
• Diagnosis of parasitic infection is based on clinical presentation and laboratory findings.
• Nematode - Lymphatic filariasism is a parasitic infection caused by Entomology, the study of arthropods.
• Laboratory diagnosis involves phenotypic demonstration of the diagnostic parasitic stage, serology, and genotypic molecular techniques.
• Scabies is characterized by itching, worse at night, and for the first weeks, itch is subtle.
• Trichomonas vaginalis is a parasite that can be detected in vaginal swabs.
• Blood will be used for microscopic examination, detection of parasite antigen, and molecular diagnosis.
• Some arthropods are vectors, which are mostly insects/flies that carry or transmit disease from patients to healthy persons.
• Scabies mites cannot live more than three days without a human host and can survive up to a month when living on a human.
• Specimen for laboratory diagnosis includes stool, blood, serum and plasma, and others such as anal swab, duodenal aspirate, sputum, urine, urogenital specimen.
• Scabies mites are not visible with the naked eye but can be seen with a magnifying glass or microscopem.
• Sarcoptes scabiei causes scabies, an infestation by the itch mite.
• Medication for scabies includes benzyl benzoate.
• Scabies mites also lay eggs in human skin that hatch and grow into adult mites.
• The role of a vector includes mechanical assistance in the transfer of disease agents between hosts, and biological assistance where disease agents multiply in the vector.
• Anaemia can be caused by malarial parasite and Ancylostoma.
• Entamoeba histolytica is a medically important intestinal parasite that may invade the colon, causing bloody diarrhoea and amoebic liver abscess.
• Giardia lamblia is a medically important intestinal parasite that is worldwide distributed, affects the small intestine, causes malabsorption, and can lead to complications such as malabsorption, malnutrition, and stunted growth for children.
• Transmission of parasitic infection can occur through sexual transmission, transplacental, blood transfusion, and vector-borne methods.
• Fever and eosinophilia can be symptoms of parasitic infection.
• Loss of weight can be due to malabsorption, as seen in cases of Giardia.
• Plasmodium is the cause of malaria, with 5 species that infect man: P. falciparum, P. vivax, P. ovale, P. malariae, P. knowlesi.
• Balantidium coli is a large motile ciliated parasite that lives in the colon of pigs, humans and rodents and can lead to colonic ulceration and dysentery.
• Mechanical pressure can be caused by Hydatid cyst.
• Mechanical obstruction can be caused by Ascaris.
• Cryptosporidium parvum is a parasite that is more prevalent in the immunocompromised, presented with diarrhoea.