6: Parasites Flashcards
tape test
used for pin worm
to see if there are eggs on childs rear
Parasite definition
organism that benefits at the expense of the host
3 types of parasitic disease
protozoan
helminths
arthropods (vectors. not parasites)
protozoan
single celled eukaryotes
helminths
multicellular. usually euk worms
arthropods
insects that TRANSMIT disease
play a role in lifecycle of parasite
what do the worms have?
generally digestive, circulatory, nervous, excretory and reproductive systems
Cryptosporidium
protozoan
fecal-oral
oocysts are the infective from… takes just 10 to cause infection
what does crypto infect
humans
cattle
llamas, pigs, deer
symptoms of crypto
extreme diarrhea for 10-14 days
dehydration
flatulance and bloating
nausea and vommiting
treatment of crypto
pretty ineffective drugs (but there are some)
NO VACCINE
immunoflourescent assay
helps find the protozoan to diagnose the disease
why do we care about Crypto
treatments not the best
deadly in immuncompromised people and kids
potential bioweapon… easy to put in water
where do people get crypto
pools
camping (contaminated water from wildlife)
daycares
farms
takes a long time for the chlorine to work to kill it
crypto outbreak in Milwaukee
104 died, 403,000 infected
because they changed the filtration system for the water
noticed bc all the pepto bismol was bought up
crypto in children
20% of all childhood diarrhea worlwide
cause poor cognitive function and inability to thrive
can be deadly
Giardia
water borne protozoan
ID’ed by immunoflourescent assay
Trypanosomiasis
African (T. brucei)… mostly south america
American (T. cruzi)
Spread of African Trypanosomiasis
seitzie fly bite… saliva
Spread of American Trypanosomiasis
Kissing bug defication before feeding
Trypanosoma brucei
African
protozoan parasite
bloodborne pathogen via vector
quick and slow versions
Trypanosoma brucei Quick version
fever, headache, swollen lymph node
later invades CNS, mental deterioration, death within a MONTH
Trypanosoma brucei Slow version
initially: no symptoms
1-2 years later: fever, headache, muscle ache, swollen lymph node
mental deterioration, fevers, personality changes, sleep changes, paralysis, death after 3 years
Trypanosoma brucei treatment and prevention
Drugs if you catch it early
no vaccine
avoid contact with bugs
why there is no vaccine for Trypanosoma brucei
Antigenic variation: the protozoa changes its coat proteins to avoid being caught and killed
Antigenic variation:
changing coat proteins (surface antigens)
so that immune cells can’t catch it and kill it
Trypanosoma cruzi
American Trypnosomasis
Chagas disease
spread by kissing bug.. its on you, you rub it in, gets to blood stream
bugs bite at night when CO2 and heat around your face
anesthetic bite… you don’t feel it
How to differntiate cruzi from brucei
cruzi is C shaped
brucei is elongated
easy to pick out in endemic countries (south america)
Trypanosoma…
you can get cruzi and other trypanosomaisis
makes it harder to diagnose
some species dont cause any harm… so it can make diagnosis hard and more important
Trypanosoma cruzi
protozoan parasite
bloodborne pathogen spread by vector
acute and chronic
Trypanosoma cruzi acute
swollen eye (Romanas sign), fever, fatigue, aches, muscle pain, headache, rash, diarrhea
Trypanosoma cruzi chronic
spreads to tissues
parasites not in blood, so asymptomatic
BUT in 20-30 years enlargement of organs bc immune system attacks body cells can cause DEATH
spread by blood transfusion
Trypanosoma cruzi treatment and prevention
actute: drugs
chronic: some help from drugs, no cure
Prevention: blood screening, mosquito nets, pesticides
Trypanosoma cruzi: ways it can be spread other than by kissing bug
breast milk
congenital
lab accidents
blood transfusions
Why we care about Trypanosomasis
More than 10,000 new yearly Africa cases Cousin vector in S. US. rampant in US wildlife 41,000 new cases in endemic countries orally 14,400 new congenital cases annually
congenital
spread from mother to fetus across placenta
Tape worms
Flat worms
Taenia
Hemlinths
Oral transmission from tainted meat
Taenia solium
pork tapeworm
Pigs (not humans) intended to ingest the eggs
if humans ingest eggs: they go to your brain and make it holey
humans are supposed to get it from pig meat
Taenia saginata
beef tapeworm
tapeworm symptoms
pretty much none
tapeworm treatment
drugs
no vaccine
Taenia solium: why do we care
can cause cytercerocis which leads to neurocystercerosis
holes in brain!
under reported and hard to diagnose
neurocystercerosis from Taenia solium
seizures, headaches, confusion, imbalance, brain swelling, excess fluid, stroke, DEATH
looking for Taenia solium
check pig’s tongue for knobs
look at meat for knobby cyst
Ascaris
round worm Heminths: largest and most common in human Oral transmission Ascaraiasis (disease it causes) neglected tropical disease
Ascaris reproduction
eggs can live for 15 years
1 worm can make 200,000 eggs per day
so number you have is important, more worms are way worse than a few
spread of Ascaris
human fertilizer used in developing countires
contaimanted water
not cleaned food
Ascaris symptoms
none in 85% of cases with few worms organ inflammation intestinal bowel obstruction malnutrition (bc worms take up lots of room)
treatment of Ascaris
drugs, surgical intervention
no vaccines
prevention of Ascaris
clean your food!
don’t use “night soil” (human feces) for fertilzer
improve sanitation
filtration to remove eggs
why we care about Ascaris
really common in Africa, SE Asia, and sometimes in US Gulf Coast… 2% of US pop (4 million ppl)
Malaria
Protozoa spread by athropod
Plasmodium: 5 species
Plasmodium
Malaria
spread by Anopheles moquito via bite
5 species… different symptom durations for each
Anopheles
mosquito that spreads Plasmodium (Malaria)
DEFINITIVE host for plasmodium
definitive host
harbors sexual reproductive stage
anaopheles mosquito for plasmodium
intermediate hosts
asexual reproduction/non-reproductive forms
human for plasmodium
reproduction of plasmodium
sexual and asexual (binary fission type thing)
Prevention of Malaria
we used to use DDT
now: Netting, control breeding sites, change water salinity, kill mosquitos
malaria vaccine
there isn’t one
hard to make because of ANTIGENIC VARIATION (parasite changes coat protein)
Once plasmodium gets into host:
1 hour from injection of sporozoites to liver
in 1 week: 10,000 offspring from ONE parasite in LIVER
Go to RBC: 10-20 more parasites once it gets to RBC
2 weeks: ONE parasite becomes millions
Malaria symptoms
headache fever spleen enlargement and then hardening chills, sweating dry cough nausea and vomiting ANEMIA organ failure
why Malaria causes Anemia
effects RBCs…body isn’t getting the O2 you need
Malaria and Spleen
becomes soft at first, can be easily ruptured
then hardens, loses function
why aren’t there new anti-malaria drugs
Because of Big Pharma… there would not be enough monetary incentive since the people who need the drug don’t have the money and wed basically have to give it away
Malaria and multiple infections
limited acquired immunity… you can lose it in just 9 months to lose partial immunity
Malaria and history
fall of Roman Empire
Rise of Christianity
over 1 million deaths in Civil War
Malaria and other diseases
increase in HIV transmission because children with severe Malaria need blood transfusions
Other reasons we care about Malaria
40% of Malaria drugs in Asia are counterfeit
219 million cases world wide, 660,000 deaths in 2010
HUGE economic loss: $12 billion a year just in Africa
