Parasitic Infections of CNS Flashcards
Parasitic infections encompasses what type of infections of CNS
any infections that are not bacterial, fungal or viral
Why are parasitic infections difficult to diagnose
nonspecific symptoms and poor reliability of serological tests
How have parasitic infections become a burden to public health in the developing world
increased tourism, migration, and AIDS epidemic facilitated spread of previously geographically restricted infections
Parasites
organism that lives on or in a host organism from which it gets its food
what are the two types of parasites
true parasite and accidental
true parasite
humans are required to complete life cycle
accidental parasite
humans are a dead-end host; no benefit to either
what are the main three clinical classes of parasites
- protozoa
- helminths
- ectoparasites
protozoans
microscopic, unicellular eukaryotes, free living or parasitic in nature
helminths
large, multicellular organism, free living or parasitic
example of helminths
cestodes (tapeworms)
nematodes (roundworms)
trematodes (flukes)
Ectoparasites
animals that attach or burrow into skin and feed on host for relatively long periods of time (days to weeks)
4 examples of ectoparasites
- ticks
- fleas
- lice
- mites
Examples of protozoa parasitic infections (not vector borne) (4)
- naegleria (brain eating amoeba)
- acanthamoeba
- balamuthia
- toxoplasma
2 examples of protozoa CNS parasitic infections
- plasmodium (malaria)
- trypanosoma
8 examples of helminths CNS parasitic infections and the animal that causes them
Tapeworms
- taenia
- coenurus
- spirometra
Roundworms
- angiostrongylus
- trichinella
- onchocerca
Flukes
- schistosoma
- paragonimus
What CNS parasitic infection has the highest burden
plasmodium (malaria)
Amoebic infections
- Naegleria, Acanthamoeba, and Balamuthia
- Free-living, environmental organisms
- Clinical manifestations:
- primary amoebic meningoencephalitis (PAM)
- granulomatous amoebic encephalitis (GAE)
- Different etiologies, risk factors, duration of illness, clinical features,
and laboratory and imaging findings - Commonalities: <5% survive despite treatment
PAM
- n. fowleri
- fulminant, acute disease aka a necrosis of frontal lobes
- acute inflammatory response which contributes to damage
- mortality greater than 95%
- common in warmer regions and warmer months
3 stages of life for N. fowleri
- amoeboid trophozoites
- flagellates
- cysts
Life cycle of n. fowleri
- amebic trophozoites are the infective form
- flagellates are temporary, non feeding, cells
- both trophozoites and flagellated forms are found in CSF
- cysts are survival form - dormant, stress resistant
- cysts never reported in brain tissue -> 1 case report of infection after inhalation of cysts
How does n. fowleri enter body and CNS
- found in poorly chlorinated pools, and thermally polluted water bodies
- enter CNS via nose where alien binds to olfactory mucosa and penetrates respiratory epithelium then migrates through olfactory nerves into CNS
CSF analysis of N. fowleri
similar to bacterial meningitis
- low glu
- high proteins
- High WBC count, PMNCs
