Flashcards in 1. Tropical Medicine- Parasitic Infections Goldsmid Deck (33):
Infectious agents are characterised into what categories?
Rickettsiae and chlamydia
Parasites: PROTOZOA, HELMINTHES, ARTHROPODS
What are the properties of a virus?
No cell wall/cell body
DNA or RNA
No metabolic enzymes
Classify the viral infections by organs involved*
What viruses commonly cause respiratory infection?
What viruses commonly cause GIT infection?
What viruses cause liver infection?
Hep E virus
Arborviruses (arthropod bourne viruses- eg mosquitoes mainly) cause distinctive pathologies- name some viruses and what they cause
Dengue Viruses- Mosquitoes
Ross River Virus - Mosquitoes
Yello Fever Virus - Mosquitoes
Japanese encephalitis - mosquitoes
Tick-borne encephalitis virus – Ixodid ticks (Tics are widespread in tropical areas – important)
Sandfly fever virus – Phlebotomus sandflies
There are haemorrhagic Viruses
Many newly recognised/emerged types:
o Marburg virus
o Ebola virus
o Hendra virus
o Hanta virus
Common Miscellaneous Viruses
• HIV virus
• Epstein Barr virus
• Rabies/Lyssa virus
• Papilloma viruses
• Orf virus
• Smallpox virus
What are the properties of bacteria?
Prokaryotes (no nuclear membrane, no organelles in the cytoplasm except ribosomes)
No discrete nucleus
Mucopeptide Cell wall (muramic acid- target site for abx)
Metabolic Enzyme systems
Name common GRAM POSITIVE rods
• Corynebacterium listeria
Name common GRAM POSITIVE cocci
Name common GRAM NEGATIVE rods (bacilli)
= peptidoglycan wall, mainly GIT organisms
Name common GRAM NEGATIVE cocci
3 common bacteria cannot be classified via this system, what are they?
• Rickettsia spp ((Cell wall deficiency or they have no cell wall))
• Chlamydia spp
• Mycoplasma sp
How do we classify FUNGI?
Filamentous::: Dermatophytes – Aspergillus
Yeasts – Candida, Cryptococcus
What are PARASITES?
Animal organisms – eukaryote cell structure
Can be single celled (protozoa) or multicellular (helminths, arthropods)
Because they are similar to us, it is difficult to treat
How do we classify PARASITES?
What are the types of life cycle for a PARASITE?
With parasitic infections, a knowledge of the life cycle is essential to understand the epidemiology, clinical course of the infection & to plan control measures.
- Direct – host A carries infection & passes it onto host A
- Indirect – goes from host A to host B (ie human to mosquito!), back to host A
What are the STAGES of a life cycle of a parasite?
In the life cycle: you can identify the definitive host, the intermediate host and/or vector (carrier), the infective stage (infects humans) & the diagnostic stage/s of the parasite.
What are PROTOZOA parasites, and how do we classify them?
Single celled eukaryotes, classified by LOCOMOTION
1. Flagellates- hair like flagellae used
2. Ciliates- small brush like structure
3. Sarcodonia (amoebae) - pseudopodia allow them to flow in that direction
4. Sporozoa- no organs of movement at all!
what kinds of infections can protozoa cause?
Protozoan infections- intestinal
Protozoan infections: blood borne
Malaria (Plasmodium spp)
African Sleeping Sickness
Chaga’s Disease (Trypanosoma cruzi)
Kala azar (black fever)
Protozoan infections: tissue infections
Protozoan infections: atrial infections
HELMINTHS(worms) are a type of METAZOA (parasite)
Platyhelminths are a type of Metazoa, what do they cause?
Flat worms (dorsoventrally flattened)
Includes the trematodes (flukes) & cestodes (tapeworms)
What is a trematode?
Type of Platyhelminth (Metazoa parasite) which
is unsegmented, mostly Dorsoventrally flattened
No body gavity but do have a gut
All have a life cycle involving a snail intermediate host
o Important species →
: Liver fluke (Fasciola hepatica) – endemic in aus
: Blood flukes (Schistosoma spp)
o Other species of note include:
• Chinese liver fluke (Clonorchis sinensis)
• Intestinal fluke (Fasciola buski)
• Lung fluke (Paragonimus spp)
What is a cestode?
TAPEWORM, type of platyhelinth (metazoa parasite)
Adult tapeworms are segmented with a scolex for attachment
Have NO GUT
NO body Cavity
Form larvae cystercerci or hydatid cysts
o Important tapeworms include →
:Beef tapeworm – Taenia saginata (endemic in Aus)
:Pork tapeworm – Taenia solium
:Hydatid tapeworm - Echinococcus granulosus
o Other species of note:
• Dwarf tapeworm = rodentolepis nana (endemic in Australia
What are nematodes?
ROUND tapeworm, platyhelinth (metazoan parasite)
Round in transverse section
Have both gut & body cavity
Usually separate male & female worms
Important species of intestinal nematodes (all endemic in Aus) include:
::Ascaris lumbricoides – Intestinal roundworm
::Trichuris trichiura – Whip worm
::Ancylostoma duodenale – Hookworm
:: Necator americanus – Hookworm
:: Enterobius vermicularis – Thread/Pin worm
:: Strongyloides stercoralis
• Other species of note:
o Dog/cat hookworms - Cutaneous larva migrans
o Dog/cat ascarids (Toxocara spp) – Visceral larva migrans
o Trichina worms (Trichinella spp) – Trichinosis (endemic in Tas)
o Filarial infections (esp Wuchereria bancrofti) - Lymphatic filariasis
What are the properties of insects?
Adult insects have a head, thorax, abdomen and 6 legs.
Important insects include:
- Jigger fleas
Other species include mosquitoes & fleas which are important vectors of disease. Some insects may be of importance due to being poisonous or due to bites/stings
Hymenoptera (one of the largest orders of insects)
What are arachnadia?
• Have a body in 2 parts.
The cephalothorax & the abdomen
Have 8 legs
Include the following arthropods: Acarina, spiders, scorpians