Chapt 23, 24, 25 Flashcards
Define:
Definitive Host
Intermediate Host
Definitive host: Reproductive cycle completed
Intermediate host: Any other life stage
Name 2 life stages of protozoans
Trophozoite: actively growing
Cyst: dormant, environmentally resistant
Define flagellates and give 4 examples of flagellate genera
Flagellates are protozoa that have at least one flagellum. Trypanosoma Leishmania Giardia Trichomonas
What part of the host are Giardia intestinalis found?
Found in intestinal tracts of animals
How many nuclei do Giardia intestinalis trophozoites have?
2 nuclei
How is Giardia intestinalis spread?
Transmitted via ingestion of cysts in contaminated water and food.
Describe the life cycle of Giardia intestinalis
Giardia trophozoites multiply in the small intestine. The trophozoites are excreted in feces and encyst once out of body.
Signs and symptoms of Giardiasis
Range from asymptomatic infections to significant gastrointestinal disease. Explosive, foul smelling, greasy diarrhea. Some people get sever joint inflammation, itchy rash.
What is the organism that causes Trichomonasis
The flagellate Trichomona vaginalis.
Describe the appearance of Trichomona vaginalis trophozoites under a microscope.
Oval or pear shaped, 5 flagella, undulating membrane.
Where does Trichomona vaginalis attach in their human host?
Women: vulva and vagina
Men: urethra and prostate
How is Trichomona vaginalis transmitted?
Sex
Signs and symptoms of Trichomonasis
Women: vaginitis–foul smelling greenish yellow discharge, intense itching, lesions on vagina and cervix.
Men: typically asymptomatic. Possible inflammation of urethra and bladder.
What are the 4 main species of protozoa that cause malaria, and which species causes the most severe disease in humans?
Plasmodium falciparum
P. vivax
P. ovale
P. malariae
What is an apicomplexan, and give two example of apicomplexans
Apicomplexans have some organelle structure at the apical part of the cell. They are an amoeboid, intracellular protozoan.
Examples: Plasmodium spp., Toxoplasma gondii.
What is the transmission vector of Plasmodium spp.?
Mosquito vector
What are the definitive and intermediate hosts of Plasmodium spp?
Definitive host: female Anopheles mosquito
Intermediate host: humans, cattle
Describe life cycle of Pasmodium
- Sporozoites injected into host during blood meal.
2*. Sporozoites invade liver cells and undergo schizogony (fission). - Liver cells rupture and release merozoites into blood.
- Merozoites penetrate erythrocytes and become trophozoites, which undergo schizogony to produce more merozoites. (Erythrocytic cycle)
- Some merozoites develop into gametocytes within erythrocytes.
- Mosquito ingests gametocytes during blood meal and undergo sporogonic cycle in mosquito.
What is the disease that is the reason pregnant women should avoid changing cat litter, and what is the organism that causes it?
The disease is Toxoplasmosis, which is caused by the protozoan Toxoplasma gondii. T. gondii is an apicomplexan. Major reservoirs are wild and domestic mammals/birds.
Transmission of Toxoplasma gondii
Consumption of undercooked meat.
Ingestion/inhalation of contaminated soil.
Definitive and intermediate host of Toxoplasma gondii
Definitive host: cat
Intermediate host: human, rodent, cattle, pig
Describe the life cycle of Toxoplasma gondii
- Sexual reproduction of parasite in cat’s digestive system, and immature oocytes shed in cat feces.
- Oocyst produces intracellular sporozoites.
- Oocysts* are ingested by host such as cat, mouse, human, or livestock.
- Sporozoites invade tissue, producing pseudocysts, which contain bradyzoites.
- Bradyzoites* are ingested by humans in undercooked meats.
Toxoplasma gondii can cross the placenta. T/F
True
What are the scientific names of the beef tapeworm and pork tapeworm
Beef tapeworm: Taenia saginata
Pork tapeworm: Taenia solium
Taenia saginata definitive host and intermediate host
Definitive host: Human
Intermediate host: Cattle
Taenia solium définitive host and intermediate host
Definitive host: Human
Intermediate host: Human or pig
Describe the life cycle of Taenia spp
- Eggs and egg-filled proglottids pass into the environment in feces.
- Intermediate hosts ingest eggs on contaminated food.
- Eggs hatch into larvae that penetrate the intestinal wall and migrate to other tissues.
- Larva develops into a cysticercus in muscle.
- Humans ingest cysticercus in raw or undercooked contaminated meat.
- Cysticercus encysts, attaches to mucosa of small intestine, and matures.
- Adult worm forms new proglottids.
Dipylidium caninum definitive host and intermediate host
Definitive host: Dog (also foxes, cats, small humans)
Intermediate host: Flea
Describe the life cycle of Trichinella spiralis
- Ingestion of undercooked encysted pork or wild game.
- Cyst wall removed by ingestion, worms mate in intestine.
- Eggs hatch in female body.
- Larvae leave female body, enter blood stream/lymph.
- Move into muscle, liver, heart, lungs and encyst.
Enterobius vermicularis intermediate and definitive host
Humans are both definitive and intermediate host
Life cycle of Enterovius vermicularis
- Ingested eggs hatch in intestine.
- Larvae mature and mate in intestine.
- Female pinworms leave hosts body and deposits eggs in perianal area.
Name the Happy (HHAPPP) group of DNA viruses and the diseases they cause
Hepadnaviridae - Hepatitis B
Herpesviridae - Herpes simplex, chicken pox, EBV, CMV
Adenoviridae - Respiratory infections, colds
Poxviridae - smallpox, cowpox
Parvoviridae - “fifth disease”
Papovaviridae - Human papilloma (warts)
Which is the most prevalent of the DNA viruses
HHV (Human Herpesvirus)
What are the characteristics of HHV?
- Enveloped
- Polyhedral capsids
- Linear dsDNA
- Latent
What is the disease caused by HHV-1, and in which nerve is it latent?
Cold sores
Latent in trigeminal (V) nerve
What is the disease caused by HHV-2, and in which nerve is it latent?
Genital herpes
Latent in sacral ganglia
Which viruses make up the herpes simplex viruses
HHV-1 and HHV-2
What is the disease caused by HHV-3
Chicken pox (Varicella)
What is the disease caused by HHV-4, and where does it become latent
Epstein-Barr Virus Infections
Latent in B cells (suppresses apoptosis, causing B cell proliferation)
What disease does HHV-5 cause
Cytomegalovirus
Cytomagalovirus (HHV-5) is a common infection in humans. What are special concerns for exposure to this virus?
In-utero exposure and organ transplants due to suppressed immune system.
What is the disease from Papovaviridae (HPV)?
Papillomas (warts)
How is HPV transmitted?
- Direct contact, including sexual activity
- Fomites
- Autoinoculation
What are the different types of Hepatitis Viruses?
Hepatitis A - Infectious hepatitis Hepatitis B - Serum hepatitis Hepatitis C - Chronic hepatitis (NANB) Hepatitis D - Delta agent hepatitis Hepatitis E - Enteric hepatitis
Which ones of the hepatitis viruses are transmitted via fecal-oral, and which ones are blood borne?
Hepatitis A and E are fecal-oral.
Hepatitis B, C, and D are blood borne.
Which one of the 5 Hepatitis viruses is a DNA virus (vs RNA)?
Hepatitis B (Hepadnaviridae) is a DNA virus.
Why is there no immunity following a Hepatitis E infection?
Hepatitis E is an Enteric hepatitis, affecting the gut. There is not a lot of T cell surveillance in the gut, hence no acquired immunity.
The Epstein-Barr virus is implicated in all of the following diseases EXCEPT:
a) Infectious mononucleosis
b) Burkitt’s lymphoma
c) Cervical cancer
d) Chronic fatigue syndrome
e) Nasopharyngeal carcinoma
c) cervical cancer
The first step in biosynthesis of Retroviruses (e.g. HIV) is:
A) direct translation of RNA into protein
B) replication of RNA
C) transcription of RNA from DNA
D) reverse-transcription of RNA into DNA
E) replication of DNA
D) reverse-transcription of RNA into DNA
