Introduction to Parasitology Flashcards
Parasitic infection represent more than ___% of those listed in the WHO list of neglected tropical diseases
50%
_____ and _____ are among the common agents of infections that affect ASEAN countries
Helminths and protozoans
Two ways of animals obtaining food
Predation and Scavenging
May attack another living animal, consuming part of all of its body for nourishment
Predation
An animal deriving its nutrition from already dead animals, either devouring those dead of natural causes or taking the leavings of a predator
Scavenging
“living together”
Symbiosis
Refers to association of two species for food and shelter
Symbiosis
Latin for “eating at the same table”
Commensalism
Denotes an association that is beneficial to one partner and at least not disadvantageous to the other
Commensalism
Symbiosis example: Entamoeba coli lives in the lumen of the intestine, subsists there on the bacterial flora of the gut, and does its host no appreciable harm
Commensalism
Involves an intimate relationship between the two species, and it is this close and prolonged contact the differentiates parasitism from the predatory activities of many non-parasites
Parasitism
A way of life may be the only possibility for a given organism, or it may be but one alternative
Parasitism
A branch of biology that is focused on the animal parasites of human and their medical significance and public health impact
Medical parasitology
Covers phenomena of dependence among living organisms
Medical parasitology
The scientific study of a parasite, an organism that depends, and a host, an organism that provides shelter and nourishment
Parasitology
Known as the organism that provides physical protection and nourishment to the parasite
Host
Type of host that harbors the adult or sexually mature stage or parasite
Definitive/final host
Example of host: Human is the _____ for lymphatic filarial worms that cause elephantiasis and trypanosomes that cause African trypanosomiasis
Definitive/final host
Type of host that harbors the larval stages or asexual forms of the parasites
Intermediate host
Harbors the early larval stage of the parasites
First intermediate host (1st IH)
Used to describe a vector which assist in the transfer of a parasitic form between hosts but is not essential in the life cycle of parasite
Mechanical vector
A type of host where a parasite remains viable but does not develop
Transport/paratenic host
Harbors the infective larval stage of the parasite
2nd intermediate host (2nd IH)
A type of host that harbors the parasite in an underdeveloped or in arrested state of development
Paratenic host
Will only continue the life cycle of parasite only if this paratenic host carrying the parasite is consumed by a susceptible definitive host
Paratenic host
In Paragonimus westermani, fresh water prawn/crab acts as its _____ while wild boar acts as its _____.
second intermediate host, paratenic host
Alternative host to a parasite that is harbored normally by humans
Reservoir host
Host that continues the life cycle of the parasite and acts as an additional source of infection
Reservoir host
Pigs are known _____ of Balantidium coli
reservoir host
The normal host is an animal but can produce disease in human if they become infected accidentally is known as zoonosis
Reservoir host
Organisms that depend on the host for survival
Parasite
Parasite: organism that cannot survive in any other manner in the absence of a host
Obligate parasite
Parasite: organism that may exist in a free-living state or as a commensal and that, if opportunity presents itself, may become parasitic
Facultative parasite
Parasite: obligatory at one or more stages of their life cycles but free living at others
Temporary parasite
Parasite: small organisms, such as mosquitoes, which must periodically seek out other and larger forms on which to nourish themselves
Intermittent parasite
Parasite who visit their host during feeding time
Intermittent parasite
parasites living within the host
Endoparasite
parasites that are found on the surface of the body
Ectoparasite
evolutionary changes that make possible existence in an unfavorable environment
Preadaptation
Groups that contain nothing but parasitic forms
Phylum Apicomplexa and Microsporidia
Most free-living nematodes barely attain naked-eye visibility as adults, but ______ can reach 35 cm and _____ as much as 1 mm
Ascaris, Dracunculus
Has proteolytic enzyme that aids its penetration of the intestinal mucosa
Entamoeba histolytica
Has penetration glands which produce enzyme capable of digesting the skin
Schistosoma sp. (blood fluke)
Penetrates an intestinal villus with six hooklets during its embryonic stage prior to developing into a cysticercoid larva
Hymenolepis nana (dwarf tapeworm)
Present toxic symptoms in large numbers but the precise cause is unknown; may produce severe local damage to the intestinal wall by means of its powerful suckers
Fasciolopsis buski (Giant intestinal fluke)
Erodes the intestinal wall, destroying the tissues locally by means of a proteolytic enzyme
Entamoeba histolytica
Invade and multiply in red blood cells, which are destroyed in the process and may also attach to the walls of smaller blood vessels in the brain, occluding them to produce localized ischemia
Plasmodium falciparum
May damage the host in other ways impossible for the smaller parasites
Helminth parasites
May perforate bowel wall, cause intestinal obstruction if present in large numbers, and ectopically may invade the appendix, bile duct, or other organs
Ascaris lumbricoides
Suck blood deprive the host of more iron than is replaced by diet and therefore leading to a case of microcytic hypochromic anemia
Human Hookworms (like Ancylostoma duodenale and Necator americanus)
Selectively removes vitamin B12 from the alimentary tract, producing a megaloblastic anemia in some infected persons
- Broad fish tapeworm Dibothriocephalus latus
F (a- and b-): demonstrates resistance to Plasmodium vivax infection
Duffy null phenotype
associated with increased resistance to Plasmodium falciparum infection
Sickle cell trait
High-protein diet is unfavorable for the development of many ____
intestinal protozoa
Low-protein diet favors the appearance of symptoms of _____
amoebiasis
Rich-carbohydrate diet favors the development of _____
certain tapeworms
resistance to hyperinfection and has a great importance in endemic areas in limiting the extent of infection with plasmodia, hookworms, and other parasites
Premunition
Parasitic infection associated with patient undergoing aggressive treatment for leukemia
Toxoplasmosis
Parasitic infection associated with corticosteroids
Acute amoebic colitis
Parasitic infection associated with state of malignancy: reticulum cell carcinoma
Primary gastric amoebiasis
Parasitic infection associated with immunologically compromised hosts
Strongyloidiasis and trichinosis
Parasitic infection associated with Acquired immunodeficiency Syndrome (AIDS)
Toxoplasmosis
Cyclosporiasis
Cryptosporidiosis
Cystoisosporiasis
Strongyloidiasis (disseminated form)
infective stage is called the cyst
Encysting protozoans
infective stage is called the trophozoite
Non-encysting protozoans
a commensal organism that inhabits the mouth, has not cyst stage or other means of survival outside of the host, and it probably is transferred by direct contact
Entamoeba gingivalis
unable to form cysts, but it probably can survive for short periods outside the body
Trichomonas spp. (T. tenax, T. hominis, T. vaginalis)
examples of soil-transmitted helminths that infect host through ingestion of embryonated eggs
Ascaris lumbricoides and Trichuris trichiura
a contact transmitted parasite whose embryonated eggs can be either ingested or inhaled
Enterobius vermicularis
involves only one intermediate host
Monoxenous
involves more than one intermediate host
Heteroxenous
Refers to the development of a parasite in its earliest form and its survival and development in the outside environment and within the host
Life cycle
Parasite with definitive host but no intermediate host required
Ascaris spp.
Definitive host of Ascaris spp.
Man/pig
Parasite with definitive host with one intermediate host required
Echinococcus granulosus
Definitive host of Echinococcus granulosus
Dog and other candidate
Intermediate host of Echinococcus granulosus
Sheep, goat, swine, cattle, horse, herbivores, human
Parasite with definitive host with two or more host required
Fasciola hepatica
Definitive host of Fasciola hepatica
Water buffalo/man
Intermediate host of Fasciola hepatica
1st IH: snail
2nd IH: aquatic plants or vegetation
Soil-transmitted helminths
Ascaris lumbricoides
Trichuris trichiura
Hookworm
Infective stage and MOT of Ascaris lumbricoides and Trichuris trichiura
Embryonated egg; ingestion
Infective stage and MOT of hookworm
Filariform larva (L3 larva); skin penetration
Food and water-borne parasites
Balantidium coli
Paragonimus westernani
Schistosoma spp.
Giardia duodenalis
Infective stage and MOT of Balantidium coli
Cyst; ingestion
Infective stage and MOT of Paragonimus westernani
Metacercaria; ingestion
Infective stage and MOT of Schistosoma spp.
Cercaria, skin penetration
Infective stage and MOT of Giardia duodenalis
Cyst; drinking contaminated water
Vector-borne parasite/s
Plasmodium spp.
Infective stage and MOT of Plasmodium spp.
Sporozoite; bite of an infected vector
Contact-transmitted parasite/s
Enterobius vermicularis
Infective stage and MOT of Enterobius vermicularis
Embryonated egg; direct contact, inhalation, ingestion, autoinfection
Sexually transmitted parasite/s
Trichomonas vaginalis
Infective stage and MOT of Trichomonas vaginalis
Trophozoite; direct contact, sexual intercourse
Phylum: equipped with pseudopods (false feet)
Phylum Sarcomastigophora
Phylum: equipped with cilia, hair-like structures
Phylum Ciliophora
The only ciliate parasite of humans
Balantidium coli
Phylum: not equipped with definite locomotor apparatus
Phylum Apicomplexa
Phylum: Flatworms
Phylum Platyhelminthes
Three classes under Phylum Platyhelminthes
Turberllaria, Trematoda, Cestoda
Differences among Turbellaria, Trematoda, Cestoda
Turbellaria: free-living forms
Trematoda: “flukes”; leaf-shaped and slender
Cestoda: “tapeworm”; elongate and ribbon-like body
Phylum: roundworms
Phylum Nemathelminthes
Phylum: thorny-headed worms
Phylum Acanthocephala
segmented and bilaterally symmetrical
animals with a body enclosed in a stiff, chitinous covering or exoskeleton and bearing paired, jointed appendages
Arthropods
Four classes under Phylum Arthropoda
Crustacea (aquatic forms), Chilopoda (centipedes), Arachnida (spiderlike), Insecta (most important)
Order: sucking lice
Order Anoplura
Order: true bugs, wingless bedbugs
Order Hemiptera
Order: beetles
Order Coleoptera
Order: ants, bees, wasps
Order Hymenoptera
Order: fleas
Order Siphonaptera
Order: one pair of true wings
Order Diptera
Phylum: endoparasitic forms; known as tongue worms or linguatulids
Phylum Pentastomida
Phylum Microsporidia is formerly classified with the _____
Sporozoa
