general CP Flashcards
how much of diagnosis does CP aid?
up to 70%
what are the subdivisions of CP?
immunology, autopsies, biochemistry, haematology, tissue samples and microbiology
what does CP comprise?
it is aetiology and epidemiology, functional, biochemical and anatomical changes and natural history and prognosis
what is a parasite?
it is an organism that lives in or on another organism which is it’s host. It benefits by deriving nutrients at the host’s expense
what is the host? what are the types of host?
a host is an organism which harbours the parasite.
define symbiosis?
when two species live together and have a close, long term interaction
what is mutualism?
an association in which both species benefit from the interaction. A definitive host is when the host harbours the adult stage of the parasite or when the parasite comes to use the sexual method of reproduction. A reservoir host is when the species infected serves as a source of infection for other species. An intermediate host will harbour the parasite during the asexual or larvae stages of the life, and is essential stage for the parasite. A paratenic host will harbour a parasite where it remains viable without further development.
how is parasitism and commensalism different?
in parasitism the parasite derives all benefit and the host gets nothing but always suffers some injury, whereas in commensalism the parasite is only deriving the benefit without causing injury to the host
which phylum of parasites do ameoboids, flagellates, sporozoans and trypanosomes belong to?
the phylum is protozoa
what are platyhelminths?
they are flukes and tape worms - flat worms
what are roundworms?
they are nematodes
which phylum do ectoparasites and blood sucking arthropods belong to?
arthropoda
what are protozoa?
they are single cell organisms - they are free living or parasitic and multiply in humans
give an example for the types of protozoa?
giardia - flagellate - fecal oral
entamoeba - amoeboid
plasmodium - sporozoan
leishmania - trypanosome
what does entaomeba cause?
dysentry and diarrhoea
who does taxoplasma affect?
it affects those with immunodeficiencies
what are helminths?
large, multicellular organisms of which they adults are generally visible by eye and cannot multiply in humans
give an example of each type of helminth?
in platyhelminths there are cestodes (tape worms) - taenia, and trematodes (flukes) - schistosoma. In nematodes there are intestinal or tissue nematodes. Intestinal is ascaris and tissue is onchocerca.
what are ectoparasites?
they are both blood sucking arthropods and those that burrow into skin. They are important transmitters of infection
what are examples of ectoparasites?
insects - anopheles or aedes
lice - pthiris pubis
mites - scabies
arachnids - argasids
how can we divide life cycles?
simple indirect (one intermediate host), complex indirect (different intermediate hosts)or direct
what is ascariasis?
it is a macroparasite (ascaris lumbricoides) caused by an intestinal nematode. It is common in areas of poor hygiene in 3-8 year olds. There is lung migration giving Loefflers syndrome and an intestinal phase. Diagnosis is by the egg or the worm and it is treated by albendazole which prevents the worm absorbing glucose.
describe schistosomiasis?
it is Bilharzia disease casued by a fluke/trematode/macro-parasite. It is the schistosoma fluke. It can cause chronic disease such as bladder cancer and liver cirrhosis. It is often asymptomatic but can cause a symptomatic acute infection - Katamaya syndrome - rash, fever, headache, myalgia and respiratory with hepato and or splenomegaly.
what are the symptoms and causes of hepatic and urinary schistosomiasis?
urinary is cause by schistosoma haemotobium - haematuria, bladder fibrosis and dysfunction and squamous cell CA cancer. Hepatic is caused by mansoni, intercallatum and mekongi and japonocium. This causes portal hypertension, hepatosplenomegaly, liver cirrhosis and abdo pain.
what are public health complications of schistosomiasis?
renal failure, hepatic fibrosis and oesophageal varices, bladder tumours, under-nutrition, poor birth outcomes, increased HIV risk and seizures and paraplesia and anaemia
how do you treat schistosomiasis?
praziquantel - well absorbed, extensive first pass metabolism but mechanism unknown
what is the most common and rare symptom of strongloidasis?
rare - gastrointestinal disturbances in around 5% and common is classical strongyloid creeping eruption in (84%)
what can we use to treat strongyloidasis?
thiabendazole, albendazole, ivermectin - reduce immunosupressive to prescribe these
what is unusual about the transmission of strongyloidasis?
it can be sexually transmitted but only in homosexual couples but can be passed heterosexually through bronchial secretions
why is hyperinfective strongyloidasis hard to treat?
it is hard to detect - often negative serology and microscopy so need other stool cultures and concentration methods to identify
what is hydatid disease caused by?
macro-parasite - echinococcus - cestode - tapeworm. Usual hosts are sheep and dogs - humans are accidental hosts. A ruptured hydatid will have a classic waterlily appearance. There is presence of cysts in the liver (70%) and the lungs (20%). These cyst ruptures can cause hypersensitivity and secondary bacterial infections.
how can you treat hydatid?
praziquantel and albendazole
how many human species of plasmodium are there and what are they?
there are 4 human species of plasmodium (micro parasite - sporozoa/protozoa) - falciparum (around 70% of the 2000 cases each year in UK attributable to this) , malariae, vivax and ovale. Anopheles is a vector
what is the basis of malaria?
parasites rupture the red blood cells, block capillaries and cause inflammatory reactions which results in fevers and rigors, cerebral malaria, renal failure, hypoglycaemia, pulmonary oedema and circulatory collapse, anaemia, bleeding and DIC
how do we identify malaria?
if there is a traveller that has recently come back with a fever then assume malaria until proven otherwise - could also be viral haemorrhagic fever. It is tested for by thin and thick microscopy, serology and PCR
what is the treatment for falciparum malaria?
antimalarials - must complete a full oral course (atovaquone) until they can stop IV (artesunate) and supportive therapy - managemetn of associated symptoms (seizures, lactic acidosis, pulmonary oedema, renal failure)
why do Hb levels need to be checked 14 days after malarial treatment?
in around 10-15% of patients there will be haemolysis following IV artesunate treatment
what is the treatment for non flaciparum malaria?
oral chloroquine - 10 tablets - go by tablet bumber and not box as this does not show the active dose
why is it difficult to develop a vaccine for malaria?
they can change their antigenic coat rendering it ineffective
how is cryptosporidiosis transmitted?
throught the fecal oral route by cryptosporidium pavrum and hominis - sporozoan (micro-parasite) - human to human with an animal reservoir
what is the incubation period for cryptosporidiosis?
2-10 days - usually 7
what are the clinical manifestations of cryptosporidiosis?
diarrohea with mucus, bloating, cramps, fever, nausea and vomiting and is usually self limiting lasting up to 2 weeks
how do we detect cryptosporidiosis?
fecal sample - antigen detection by EIA and acid fast staining
how do we treat cryptosporidiosis?
rehydration by nitazoxanide - symptomatic and for the immunocompromised - must start HAART for HIV positive individuals and paromomycin to kill parasite (may also need azithromycin)
what are the symptoms and the cause of trichomoniasis?
it is caused by trichomonas vaginalis (flagellated protozoan) - sexually transmitted with binary fission. It can be asymptomatic in men and in women it is smelly vaginal discharge, dyspareunia, dysuria and lower abdo pain, haemorrhages on the cervix
how do we detect trichomoniasis?
direct microscopy of organisms in genital specimens and PCR is increasing
how do we treat trichomoniasis?
metronidazole - treat partner as well
what is giardiasis?
it is a flagellated protozoan through the fecal oral route
what are the symptoms of giardiasis?
it is asymptomatic or can have severe diarrhoea and malabsorption, abdo pain, nausea and vomiting that last from 1-3 weeks - can cause chronic disease
how do we identify giardiasis?
identification of cysts or trophozoites in faeces
how do we treat giardiasis?
metronidazole or tiniadazole
