MCQ Revision Flashcards
Where is t.b.gambiense found?
Western and central Africa
Where is t.b.rhodesiense found?
Eastern and Southern Africa
How many people are at risk from African trypanosomiasis?
60 million
Infective stage of HAT
Metacyclic trypomastigote
Both male and female tsetse flies take a blood meal. True or false?
True
Bloodstream stage of HAT?
Long slender trypomastigote
Infective stage of HAT to the tsetse fly?
Short stumpy trypomastigote
Short stumpy forms transform into what and where in the tsetse fly?
Procyclic trypomastigotes in the mid-gut
Salivary gland trypanosome stage which undergo sexual reproduce are called?
Epimastigotes
HAT epimastigotes produce?
Metacyclic trypomastigotes
Disease caused by T.b.brucei?
Nagana
Resistant animal trypanosomiasis cattle
N’dama
Reservoir host of t.b.rhodesiense?
African wildlife
T.b.gambiense’s primary host is….
Humans
T.b.gambiense is transmitted by which species of tsetse fly?
Riverine tsetse’ Glossina palpalis and G. tachynoides
T.b.rhodesiense is transmitted by which species of tsetse?
Glossina mortisans
What parasite causes acute sleeping sickness?
Rhodesiense
Which species causes chronic sleeping sickness?
T.b.gambiense
Symptoms of acute sleeping sickness
Chancre
Fever, headache, enlarged lymph nodes and muscle ache
Invasion of CNS causes mental deterioration
Death follows soon after
Symptoms of chronic sleeping sickness
Mild symptoms: fever, headache, muscle and joint pain
Itch skin, swollen lymph nodes
After 1-2 years: CNS involvement - personality changes, daytime sleepiness, nighttime insomnia, partial paralysis
Death after ~3 years
How would you treat early stages of HAT?
Pentamidine and Suramin
Is pentamidine effective against gambesian sleeping sickness?
No
Gambiense treatment
Melarsoprol and nifurtimox
Two species of African trypanosomes that infect humans
Trypanosoma brucei gambiense
Trypanosoma brucei rhodesiense
Parasite responsible for Chagas’ disease
Trypanosoma cruzi
Chagas is transmitted by?
Triatomine bug (reduviid or kissing bug)
Majority of individuals with Chagas’ disease are?
Asymptomatic
Reservoirs of Chagas’ disease
Many wild and domestic animals.
Opossum and armadillo
Cats and dogs important due to close contact with humans
Genus of triatomine bug in northern regions of South America?
Rhodnius
Genus of triatomine in the southern regions of South America?
Triatoma
Human infective stage of T.cruzi?
Metacyclic trypomastigote
Triatomine bugs inject metacyclic trypomastigotes into a host during a blood meal. True or false?
False
Transmission is through faeces entering biting point or mucous membrane
Intercellular stage of T.cruzi?
Amastigotes
Intracellular amastigotes of t.cruzi transform into what?
Non-dividing trypomastigotes
Clinical manifestations of T.cruzi are a result of?
Non-dividing trypomastigotes reinvading cells and multiplying as amastigotes
Infective stage of T. cruzi to the triatomine bug?
Trypomastigote
Trypomastigotes transform into _____________ in the mid gut of a triatomine bug
Epimastigote
Hind gut stage in a triatomine bug
Metacyclic trypomastigotes
Acute phase symptoms of Chagas:
Mild symptoms: fever, body aches and intestinal disorders
ROMANA’S SIGN!
Chronic phase symptoms of Chagas’ disease
Mostly asymptomatic
Dilation of digestive tract
Cardiomyopathy
Nervous system disorders
Acute phase treatment of Chagas
Benznidazole or nifurtimox
Chronic phase treatment of Chagas
None
Nifurtimox may slow progression though
T. Cruzi control includes
Vector control
Blood screening
Alternate sources of infection of T. Cruzi
Blood transfusion
Transplant
Milk?
Transgenital/vertical transmission
Land cestodes are called
Cyclophyllidea
Most cestodes are pathogenic. True or false?
False
Adult cestodes are found in the ________________
Small intestine
What is the pathogenic stage of cestodes?
Juvenile stage
General morphology of cestodes
Segmented adults No gut or anus Always parasitic Hermaphroditic Almost all have indirect life cycles
Segments of an adult cestodes are called?
Pro glottids
How would you distinguish between adult Taenia solium and Taenia saginata?
T. solium scolex has a crown of hooks
T.saginata has more branches in proglottids
Definitive host of T. solium?
Humans
Intermediate hosts of T. solium?
Pigs and humans
How many suckers do cyclophyllideans have?
Four
Where are you likely to find T. solium infection?
Areas of poor sanitation
Where pigs have access to human faeces
Egg stage of Taenia are called?
Oncospheres
Oncospheres on T. solium develop into ___________ in __________ cells.
Cysticerci
Muscle
How do humans become infected with adult T. solium?
Consumption of raw or undercooked meat containing cysticerci
How do cysticerci of Taenia solium appear in humans?
Consumption of faeces containing eggs
What is the Pathology of Taenia cysticercosis?
Cysts appearing in muscles, cutaneous tissues, eyes and brain
Neurocysticercosis
Neurological problems
Muscles weakness
Treatment for adult Taenia solium?
Niclosamide and praziquantal
What is the treatment for people who are infected with T.solium and have asymptomatic brain cysts?
Niclosamide
Praziquantal will provoke neurological symptoms
Treatment for neurocysticercosis?
Steroids can relieve symptoms
Albendazole or praziquantal may be used
How would you control Taenia spp.?
Treatment of individuals with adult worms Good personal hygiene Prevent pigs access to humans (solium) Well cooked meat Meat inspections Pig vaccination (solium)
Intermediate hosts of T.saginata?
Cattle
Definitive hosts of E.granulosus are?
Canids
Where is E.granulosus most common?
In areas where sheep and cattle are found
Areas where dogs have close contact with humans and cattle
Eggs of Echinococcus granulosus mature into?
Unilocular cysts
Unilocular cysts produce ___________.
Protoscolices
Echinococcus granulosus:
Protoscolices > ____________ > adults
Scolices
Pathology of Echinococcus granulosus
Growing Cysts occur at various organs and exert pressure
Abdominal pain, hepatomegaly, coughing, lung abscesses
Can cause neurological symptoms
Anaphylaxis from cyst rupture
Why would you not find Echinococcus eggs in human faeces?
Adults are not found in humans
Treatment for Echinococcus in humans
Surgery (PAIR) - granulosus
Albendazole and mabendazole may inctivate cysts
What control methods would be used to combat Echinococcus granulosus?
Treating dogs with praziquantal Avoid close contact with dogs Good sanitation Slaughterhouse inspection Don't feed offal to dogs Vaccinate sheep
Echinococcus multilocularis
Definitive host is _____________
Intermediate host is ____________
Foxes
Rodents (and humans)
Distribution of E. multilocularis
North America, Europe, Siberia and China
What is the only human tapeworm which does not require an intermediate host?
Ask Zach
Hymenolepis nana
Proglottids of Hymenolepis nana are longer than they are wide. True or false?
False
How do humans become infected with Hymenolepis nana?
Consumption of Arthropods
Also consuming embryonated eggs from food, water or hands
Hymenolepis nana
___________(or eggs) develop into adults in the intestine
Cysticercoid
How does reinfection occur in Hymenolepis nana?
Eggs can remain in the small intestine and hatch into adults
Treatment for Hymenolepis nana
Praziquantal
Pathology of Hymenolepis nana
Typically no symptoms
Possible diarrhoea if infection is high
Group of Fish tapeworms are called?
Pseudophyllidea
Species name for the broad fish tapeworm
Diphyllobothrium latum
Sucking grooves of Pseudophyllidea are also called?
Bothria
What is the largest parasite of humans?
Diphyllobothrium latum
Definitive hosts of D. latum
Fish eating mammals and humans
Swimming Diphyllobothrium larvae are called?
Coracidium
Diphyllobothrium latum
Coracidium > ___________ (in crustaceans) > ___________ (in fish)
Procercoid in body cavity of crustaceans
Plerocercoid in fish
How do humans become infected with Diphyllobothrium latum?
Ingestion of plerocercoid in infected fish
Pathology of diphyllobthriasis
Usually asymptomatic Abdominal pain, fatigue, diarrhoea Megablastic anaemia (vitamin B12 deficiency)
What is the treatment of Diphyllobothriasis?
Praziquantal
A) control of Diphyllobothriasis
B) would mass treatment control the disease and why?
A) reduce faecal contamination and kill/cook fish properly
B) No. Parasite can be maintained in a zoonotic cycle
Common name for Dracunculus medinensis?
Guinea worm
How do humans get Guinea worm?
Drink water containing Copepoda
Pathology of Guinea worm
Painful burning blister
Wound susceptible to infection
Sepsis and treatment
What are the General morphologically features of Trematoda?
Three life cycle stages Indirect life cycles Dorsoventrally flattened Blind ended gut No anus
Number of people infected with ascaris
1 billion
How do you become infected with ascaris?
Ingestion of eggs in faeces/soil containing eggs with viable larvae
Migration of ascaris larvae after hatching in the small intestine
Penetrate gut > liver > lungs > bronchioles > coughed up pharynx
Infective L3 larvae mature into adults on their return to the small intestine. True or false?
True
How is transmission of ascaris enhanced?
Asymptomatic individuals continuously produce eggs
Migratory symptoms of ascaris
Eosinophilia, lung inflammation, hepatomegaly and Loefflers syndrome
Intestinal symptoms of ascaris
Obstruction and perforation of bowel
Nausea
Diarrhoea
General symptoms of STHs in young children
Nutrient deficiency, growth retardation and cognitive ability reduction
How would you control Ascaris?
Improved sanitation
Education
Community targeted deworming
Correct preparation of food/water
Common name for Trichiuris trichuria
Whipworm
How are whipworm transmitted to humans?
Ingestion of embryonated eggs
Larvae development/migration in the small intestine
Large migrate to LARGE intestine and mature into adults in the mucosa
Whipworm larvae develop in the environment. True or false?
True
Pathology of whipworm
Inflammatory bowel disease
Anaemia
Bloody/watery stools
Extreme symptom of whipworm in young children
Rectal prolapse
Name two species of hookworm
Ancylostoma diode ale
Necator americanus
Hookworm life cycle
Eggs passed in stool which hatch in environment
On contact with host. L3 penetrate skin.
Migrate to blood vessels > heart > lungs > bronchioles > coughed up
Then swallowed and mature into adults in the small intestine
Hookworm pathology
Ground itch Enteritis Eosinophilia Anaemia Cardiac failure
Two species which cause cutaneous larval migrans
Ancylostoma braziliense
Ancylostoma caninum
Pathology of cutaneous larval migrans
Intense puritus
Hookworm control
Wear protective footwear
Human hookworm vaccine initiative
Common name for enterobius vermicularis
Pinworm
Where are pinworm eggs deposited?
Perianal folds
How does self infection of pinworm occur?
Scratching anus and then eggs from fingernails deposited into mouth
Hookworm Larvae hatch in the environment. True or false?
False. They hatch in the small intestine
Where do adult hookworms live?
Colon
Pathology of hookworm
Mild gastro-intestinal discomfort
Puritus
Irritability
Secondary infection
Common name for threadworms
Strongyloides stercoralis
Adult Strongyloides pass larvae in stool true or false?
True
How do humans become infected with strongyloides
Filariform larvae penetrate skin
Strongyloides larvae migration in host
Penetrate skin
Migrate to small intestine where they become adults
Strongyloides can autoinfect. True or false?
True
Pathology of Strongyloides
Diarrhoea Larval currens Abdominal pain Weight loss Immune system suppression
How is trichinella transmitted?
Consumption of undercooked meat containing larvae
Where are adult trichinella found in humans ?
Small bowel mucosa
Where do trichinella encyst?
Skeletal muscle cells
Pathology of trichinella
Nausea, diarrhoea, vomiting
Muscle pain, fever, swelling to face, headache
Causative agents of visceral and ocular larval migrans
Toxocara catis
Toxocara canis
Pathology of VLM/OLM
Fever Respiratory CNS disturbances Eosinophilia Hepatomegaly Inflammatory responses in viscera, organs and eyes
Majority of filarial infections are caused by?
Wucheria bancrofti
Where do schistosoma mansoni mature?
Liver