Protozoa and heliminthes Flashcards
1
Q
Properties of protozoa
A
- eukaryotic microorganisms
- generally unicellular
- heterotrophic -needs organic substances
- Often commensal -live in or on other organisms
- sometimes parasitic they produce eggs and eggs are transmitted in water; they have different life stages. When taking a treatment, you need to get at the right stage of the life cycle of protozoa to be susceptible to treatment
- often live in aqueous environments (water)
- often motile
- seasonal (you have outbreaks in western Europe)
2
Q
Which protozoa cause the following diseases?
- Giardiasis
- Amoebiasis
- Malaria
- Leishmaniasis
- Cryptosporidiosis
A
- Giardia intestinalis cause giardiasis
- Entamoeba histolytica causes amoebiasis
- Plasmodium vivax causes malaria
- Leishmania donovani causes Leishmaniasis
- Cryptosporidium enteritis causes cryptosporidiosis
3
Q
Malaria - how many cases in 2016?
- how many deaths?
- Africa region accounts for 91% of these deaths (as there is poor control of water and mosquitos)
- Who is more at risk?
A
- Malaria = WHO priority disease
- estimated 216 million cases of malaria in 2016
- estimated 445000 deaths
- Africa region accounts for 91% of these deaths
- Children are more at risk
- Malaria mortality rates have fallen by 21% between 2010-2015 and by 31% in the WHO African region
4
Q
Where is malaria most spreaded?
A
-South America, India, Madagascar, Africa, Indonesia, Asia
5
Q
Which protozoa causes malaria?
A
- Plasmodium = genus
- Plasmodium = ameboid intracellular patasites
- 3 different species of plasmodium cause malaria: P.vivax, P.malariae, P falciparum
- trasmitted through the bite of Anopheles mosquito’
- protozoa infects red blood cells and destroys them
6
Q
How to prevent malaria?
A
- mosquito control (insecticides, net, breading control)
- prophylaxis - choice is based on many factors: risk of exposure (DEPENDS WHERE YOU GO IN THE WORLD), extent of drug resistance (DEPENDS ON THE AREA YOU GO TO), efficacy of recommended drugs, side effects of drugs, patient related factors (age, pregnancy,renal/hepatic impairment)
- prophylaxis 1-3 weeks before travelling to endemic areas
- prophylaxis continues for up to 4 weeks after leaving the endemic areas
7
Q
Prophylaxis drugs for malaria
A
- Chloroquine (not used for falciparum malaria endemic as there is a risk of resistance)
- Mefloquine (prophylaxis where falciparum exists)
- Tetracycline (doxycycline) used where resistance exists to mefloquine and chloroquine
- Malarone (used where falciparum malaria endemic exists and resistance to other antimalarial drugs)
8
Q
Treatment drugs for malaria
A
- QUININE = makes the heme of the RBC toxic to paracyte by inhibiting hemozoin biocrystallisation
- MALARONE = INTERFERES WITH 2 PATHWAYS IN THE BIOSYNTHESIS OF PYRIMIDINES REQUIRED FOR NUCLEIC ACID REPLICATION; CYTOSINE, THYMINE, GUANINE ARE PYRIMIDINE DERIVATIVES
- Atovaquanone inhibit the electron transport chain
- RIAMET: interferes with the ability of malaria parasites to convert heam into haemozoin. This causes levels of toxic haem to rise, which kills the blood stages of malaria parasites
- A combination of treatments can be used based upon the risk
9
Q
Cryptosporidiosis
- which organism causes it?
- opportunistic infections
- symptoms
- diagnosis
- treatment:
A
- cryptosporidium parvum, hominis; both anaerobic and aerobic metabolisms
- Opportunistic infections: fecal-oral; water
- symptoms: diarrhoea, abdominal pain, nausea
severe cryptosporidiosis in HIV patients as they are immune compromised
- diagnosis: organism in stool sample
- treatment: fluid and electrolyte replacement; no licensed drugs in the UK (but you treat symptoms-medicines to alleviate diarrhoea or other pain the patient has)
10
Q
Amoebic Dysentry
- which organism causes it?
- how many people infected worldwide?
- how many deaths per year worldwide?
- route of transmission?
- Diagnosis
A
- organism which causes it: entamoeba histolytica
- 400 million people infected worldwide
- 70000 deaths per year worldwide
- route of transmission: fecal oral and water
- diagnosis:organism in stool sample
11
Q
Amoebic dysentry - symptoms
A
- gastrointestinal infection that may or may not be symptomatic and can remain latent
- range from mild diarrhoea to dysentrey with blood and mucus in the stool
12
Q
Forms of infections of amoebiasis
A
- invasion of the intestinal lining causes amoebic dysentery or amoebic colitis
- if the parasite reaches the bloodstream, it can spread through the body, most frequently ending up in the liver where it can cause amoebic liver abscesses
13
Q
Treatment for Amoebic Dysentry
A
- METRODINAZOLE =PRODRUG
- non-enzymatically reduced by reacting with reduced ferredoxin
- many of the reduced nitroso intermediates will form sulfinamides and thioether linkages with cysteine bearing enzymes
- metronidazole metabolites are taken up into bacterial DNA and form unstable molecules
- TINIDAZOLE
- DILOXANIDE FLUORATE (UNLICENSED, CHRONIC AMOEBIASIS)
14
Q
Other amoebal diseases
A
- leishmaniasis
- giardiasis
- trypanosomiasis
15
Q
Name all parasitic worms
A
- flukes
- tapeworms
- roundworms
- threadworms
- hookworms
- whipworms
