parasitology

• Phylum Platyhelminthes, also known as Flatworms, includes two groups: Trematoda and Cestoda.
• Trematodes, or Flukes, are further divided into four types according to habitat: Blood, Liver, Lung, and Intestinal.
• Blood Flukes, under Genus Schistosoma, infect the mesenteric veins and all have the same infective stage called Cercaria, which is a larva.
• The cercaria that Blood Flukes develop is a Fork Tail Cercaria, with a mouth, gut, and tail.
• The mot of penetration of cercaria to human skin can lead to infection called schistosomiasis/bilharziasis.
• Blood Flukes require two hosts: a Definitive Host (Man) and an Intermediate Host (Snails or Mollusks).
• Within the egg, there is a larva called Miracidia/Miracidium, a larva equipped with cilia.
• When eggs come in contact with water, they will hatch and look for a snail as their intermediate host.
• Once the miracidium penetrated inside the snail, it will develop into Sporocyst, the mature version of miracidium, which will later become Cercaria.
• Cercaria will eventually escape the snail and swim in water to look for man, leading to infection through skin penetration.
• When cercaria penetrates the skin of the man, the tail will be removed, and cercaria without tail is called Schistosomulum.
• Eggs are always non-operculated.
• Larval stages include Miracidium, a larva with cilia, which is released from the egg when hatched.
• Sporocyst is a sac-like larva developed from Miracidium.
• Cercaria is a larva equipped with mouth, GIT, and tail.
• Common characteristics of Blood Flukes include being Non-Hermaphroditic/Dioecious, with separate sexes (male and female schistosomas), and having a body that is not leaf-like, being somewhat elongated, with males usually shorter and robust and females longer and slender.
• Gravid refers to the terminal end, part that contains mature eggs, which undergoes detachment.
• Lifespan of Taenia spp is 25 years.
• Hypothenemia nana has a lifespan of many years due to autoinfection.
• Dcaninum has a lifespan of less than one year.
• Hymenolopis nana is both heteroxenous and homoxenous, but mostly it is homoxenous.
• The lifecycle of Hymenolopis nana consists of two lifecycles.
• The first lifecycle of Hymenolopis nana requires one host, also known as the direct lifecycle.
• The second lifecycle of Hymenolopis nana requires two hosts, also known as the indirect lifecycle.
• Phylum Platyhelminthes – Class Cestoda includes Pseudophyllidea.
• Dlatum has a lifespan of 3 hosts, with 1 DH, 2 IH.
• Taenia solium has a lifespan of 2 hosts.
• Hymenolopis nana can only have one host in the Direct lifecycle, and produces non-operculated eggs.
• Taenia saginata and Hymenolopis diminuta produce operculated eggs.
• Both male and females are provided with oral and ventral suckers, and males are provided with a Gynecophoric canal used by male worms to carry female during copulation.
• All Blood Flukes produce non-operculated eggs, whose shell remains intact, without openings, without operculum.
• Diagnostic stage for Blood Flukes is the eggs, which can be found in urine or stool depending on the specie.
• The largest Blood Fluke is Schistosoma japonicum, and the smallest is Schistosoma mansoni.
• Clonorchis sinensis is an ovoidal egg with a wide perculum, opposite the operculum is a median protuberance called "abopercular knob".
• Eggs of Clonorchis measure 29x16 um and contain developed miracidium.
• Clonorchis felineus eggs closely resemble those of Clonorchis but are elongately ovoidal with tapering ends.
• The size of Clonorchis felineus eggs is 30x11 um.
• Metagonimus yokogawai is a thin-shelled light-yellow egg that contains developed miracidium.
• Fasciola hepatica eggs are large ovoidal, yellowish brown that contain undeveloped miracidium.
• Fasciola buski eggs are yellowish and ellipsoidal with a clear thin shell and small operculum, containing undeveloped miracidium.