Parasitic infections Flashcards
define infection?
define disease ?
what is the difference?
infection : invasion by and growth of pathogenic microorganisms within the body
disease : a disordered or incorrectly functioning organ, part structure or system of the body resulting from the effect of genetic or developmental errors, infection poisons nutritional deficiency or imbalance toxicity or unfavourable environmental factors, illness, sickness or ailments
define a parasite?
organism living in or on a host and dependent on it for nutrition - normally causing damage
what are the two different types of parasite?
Endoparasites- exist inside the host
Ectoparasites - exist ON the host
what are the types of endoparasites?
Protozoa eg. • Amoeba • Coccidia • Ciliates • Flagellates
Metazoa eg.
•Roundworms
•Flatworms
• Flukes
what is a protozoa?
- These are SINGLE celled organisms
- They are eukaryotes
(they have their genome within a membrane bound
nucleus and there are complex organelles in the cytoplasm) - NO eosinophilia
what is a Metazoa?
- MULTICELLULAR organisms
- They are worms
- Free living, intermediate hosts and vectors
- some inhabit the gut (geohelminths) others invade the tissue
- There is eosinophilia if they invade the blood
what parasitic class is amoebae? what are examples?
how does it cause infection?
Amoeba eg. Entamoeba histolytica
- infection occurs by ingestion of mature cysts in food or hands contaminated by faeces
how common is infection by Entamoeba histolytica ?
- very common 10% of world infected
- It is the third most common cause of death of parasitic infections
- especially common in warm climate
what are the symptoms of infection with Entamoeba histolytica?
- 90% of infections are asymptomatic
- remaining 10% causes symptoms like intense diarrhoea
- Incubation period may be as long as 7 days
how do the cysts infect humans?
- the cysts enter the s. intestine and release active amoebic parasites
- these invade the epithelial cells of the large intestine causing flask shaped ulcers
- the infection can then spread to other organs
how to diagnose Entamoeba histolytica ?
- wet mount
- look for cysts
what is the treatment for Entamoeba histolytica ?
NITROIMIDAZOLE derivatives = act on the trophozoite but not on the cysts
- PARMOMYCINE or DILOXANIDE FUROATE
what is the difference in structure of mature cyst and immature cyst?
mature cyst: 4 nuclei
immature cyst : 1-3 nuclei
what are Coccidial infections in humans?
zoonoses
from animals
what are examples of Coccidial organisms?
Plasmodium species = malaria
Toxoplasma = toxoplasmosis (dangerous for foetus)
Cryptosporidium = diarrhoea
what are the different types of plasmodium in Malaria
Malariae Falciparum Ovale Vivax Knowlesi
what are the two types of host in malaria?
Humans
Female anopheles mosquito
what are the two stages of malaria infection in humans?
Liver
Blood
symptoms of malaria?
when do symptoms occur?
symptoms can occur as early as 7 days or as late as a year
main symptoms : • Fever • Headache • Chills • Vomiting • Muscle pain • paroxysmal (happens every 4-8 hours)
what are complications of malaria?
- Severe anaemia
- Cerebral malaria
- Liver failure
- Shock
- Pulmonary oedema
- Abnormally low blood sugar
- Kidney failure
- Swelling and rupturing of the spleen
what are treatments for malaria?
mild
severe
MILD
•Chloroquine (main one)
•Atovaquone-proguanil
•Artemether-lumefantrine •Quine sulfate
plus one of the following: Doxycycline • Tetracycline • Clindamycine quinine sulfate • Mefloquine
SEVERE
Artemisinin based combination therapy (ACT)
Toxoplasma gondii route of infection to humans
- eating undercooked meat of animals with tissue cysts
- food or water with cat faeces
- Blood transfusion
- organ transfusion
- Contaminated environmental samples
immunocompromised patients infected with Toxoplasma gondii
might develop CNS disease, brain lesions, pneumonitis or retinochoroiditis
Cryptosporidium symtoms diagnosis treatment vulnerable people
- Causes diarrhoea in humans
- stool examination
- fluid rehydration
- common in HIV
example of Ciliates?
Balantidium coli causes balantidiasis
what are the Reservoir hosts of Balantidium coli?
Pigs
Rodents
Primates
symptoms of balantidiasis ?
- most patients are asymptomatic
- immunocompromised patients may experience the following symptoms:
Persistent diarrhoea
Dysentery
abdominal pain
weight loss
vomiting
if untreated might cause perforation of the colon can occur
how to diagnose balantidiasis?
stool examination
example of Flagellates?
Giardia lamblia
which causes GIARDIASIS
how do Flagellates infect?
- Flagellated trophozoites attach by their suckers to the surface of duodenal or jejunal mucosa
- they can survive standard chlorination procedure
main symptoms of Flagellates?
- diarrhoea
- greasy stools
- stomach cramps
- dehydration
diagnosis and treatment of Flagellates?
stool examination
METRONIDAZOLE
how is Trichomoniasis transmitted?
where is most of the infection?
- sexually
- most of the infection is in the urethra
symptoms of trichomoniasis in females
10-50% are asymptomatic
Vaginal discharge
Vulval itching
Dysuria or offensive odour
symptoms of trichomoniasis in males?
15-50% are asymptomatic
Discharge
Dysuria
what are complications of Trichomoniasis?
- bad outcome of pregnancy
- associated withe low birth weight
association of Trichomoniasis with HIV?
- trichomonas infection may enhance HIV transmission
- there is also increased risk of trichomonas vaginalis in those who are HIV positive
diagnosis and treatment of Trichomoniasis?
- Microscopy and Trichomonas rapid test
- treatment METRONIDAZOLE
what are Helminths?
Complex MULTICELLULAR parasites
who are the hosts in Helminths?
humans are the definitive host
few are animals
how do the Helminths multiply
- Adult worms cannot multiply in man
- they lay eggs, microfilaria, larvae
who do Helminths affect the most?
large burden of worms in school aged children
types of roundworms?
types of flatworms?
types of flukes?
Roundworms: Ascais Hookworm filaria strongyloides
Flatworms:
Taenia (tapeworms)
Flukes :
Schistosoma
what is Ascariasis?
- Type of roundworm
- Adult worms live in the lumen of the small intestine
- they lay eggs which are passed to the faeces
- eggs become infective after 18 days to several weeks
- develop into adult worms in small intestine
- Adult worms can live 1-2 years
symptoms of Ascariasis?
Often ASYMPTOMATIC
- large number of worms might cause abdominal pain or intestinal obstruction
- might cause malnourishment
- penetration of larvae into lungs can cause Loeffler’s pneumonia
- Loeffler’s pneumonia = pools of blood and epithelial cells clog the air spaces in the lungs
diagnosis of Ascariasis?
stool examination
treatment of Ascariasis?
ALBENDAZOLE or MEBENDAZOLE
what does hookworm cause?
- This can cause iron deficiency anaemia due to localised bleeding
- They penetrate into the pulmonary alveoli ascend the bronchial tree into the pharynx and are swallowed
- the larvae reach the small intestine and develop into adult worms
- Adult worms live in the lumen of the small intestine where they attach to the intestinal wall and cause bleeding
- also causes cardiac issues
- GI issues
diagnosis of hookworm ?
treatment of hookworm?
stool examination
ALBENDAZOLE or MEBENDAZOLE
what does whipworm (Trichuris Trichiura) cause?
- large numbers of the warm can cause bloody diarrhoea and anaemia due to severe vitamin and iron loss
how does Whipworm exist in the body?
- Eggs hatch in the small intestine and release larvae that mature in the colon
- Adult worms live in the caecum and ascending colon
- the worms leave open wounds that cause inflammation in the intestinal wall
- can sometimes cause rectal prolapse
diagnosis of Whipworm ?
stool examination
treatment of Whipworm?
ALBENDAZOLE or MEBENDAZOLE
which roundworms cause
Lymphatic Filariasis ?
Brugia malayi
Wucheria bancrofti
what occurs on Lymphatic Filariasis ?
- Microfilariae (larvae) are found in the peripheral blood
- during the day the Microfilariae are in the deep veins
- in the night they move to peripheral circulation
how to diagnose Lymphatic Filariasis ?
blood smear or antigen detection with a immunochromatic test (card) or ELISA
what is Loiasis - Loa Loa ?
it is a type of roundworm
symptoms of Loiasis?
- gets into the eye
- you can see wriggling in the vision
how is Loiasis transmitted?
- confined to africa
- carried by flies
- Microfilariae circulate in the blood from where it can be picked up by the
Chrysops - In the gut of the fly the larvae mature into the infective third stage
- they take blood meals and develop into mature adults
what is tape worm?
it is a type of flatworm
which animals are humans definitive hosts for?
Taenia solium (pig) Taenia asiatica (pig) Taenia saginata (beef)
what are symptoms of tapeworm?
most patients are asymptomatic Abdominal pain Loss of appetite Weight loss Upset stomach
how to diagnose tapeworm?
tapeworm segments found in stool or identification of eggs in
stool
treatment of tapeworm?
PRAZIQUANTEL
what does Taenia solium specifically cause?
- causes CYSTICERCOSIS
- CYSTICERCOSIS this is the most commonly acquired form of epilepsy in the world
what is Schistosomiasis?
what are the three main types?
it is fluke
Schistosoma mansoni
Schistosoma haematobium
Schistosoma japonicum
how is Schistosomiasis carried?
- eggs are put into the water via faeces or urine
- they hatch and release miricidia which penetrates the snail
- the snail then releases cercariae that penetrate the skin
- cercariae mature into adults and reside in the venules
- the eggs move towards the lumen of the small intestine
symptoms of Schistosomiasis?
Possible rash or itchy skin Within 1<2 months:
• Fever
• Chills
• Cough
• Muscle aches
• Most people have NO SYMPTOMS in the early stages of infection
what happens to children with Schistosomiasis?
anaemia, malnutrition and learning difficulties
what can the parasite do after years of damage?
damage the liver, intestines, lungs and bladder
diagnosis and treatment of Schistosomiasis?
stool or urine examination
PRAZIQUANTEL
example of ectoparasite?
Scabies
what does scabies cause?
how is scabies treated?
Causes rash and the presence of burrows
it is treated with scabicides
what are the types of lice?
Pediculus humanis capitis = HEAD louse
Pediculus humanis corporis = BODY louse
Pthirus pubis = CRAB louse
what are the three stages of lice existing?
eggs
nymphs
adults
how are ectoparasites transmitted?
direct contact
