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19 Cards in this Set
- Front
- Back
Types of Vector-Borne Transmission
Mechanical Transmission |
Mechanical Transmission – simplest form
(not necessary for pathogen survival – “flying/crawling hypodermic needle” phenomenon) |
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Types of Vector-Borne Transmission
Biological Transmission |
Biological Transmission – more complex
(necessary for pathogen survival – results in amplification or development in vector) |
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Types of Vector-Borne Transmission
What are the types of Vertical Transmission |
Trans-stadial: (ticks, kissing bugs)as soon as they hatch they need a blood meal, if it picks up pathogen at 1st or 2nd feeding, will stay infected throughout
Trans-generational : Transovarial – female to progeny, including males (mosquitoes, ticks) |
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Types of Vector-Borne Transmission
What are the types of Horizontal Transmission |
Bite:(saliva or gut infection)
(malaria, dengue, filariasis, etc.) Feces : (Chagas disease) Crushing Infected Arthropod:(epidemic typhus, etc.) - ovaries become infected and they become infected when they hatch out - first blood meal they could transmit disease. |
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Horizontal Transmission Types
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Multiplicative (Propagative)
(increase in number - Dengue) - many more in end. Developmental (change stage - Filariasis) - no multiplcation, die off in host much less in end. Cyclopropagative(change stage and increase in number - Malaria) - combo of above 2 |
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Extrinsic Incubation Period - EIP
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Time interval between vector infection and potential for pathogen transmission to vertebrate host (determined by controlled experimental studies)
If vector dies before EIP is completed, transmission will not occur. |
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Ecological Parameters Affecting Vector Populations:
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Availability of food (What do they eat, and when?)
Space (Where do they occur, and when?) Water (Is their appearance seasonal – wet/dry?) Temperature (Is their appearance seasonal – warm/cold?) Predation ( Can we enhance or introduce predators to control them?) Disease ( Can we identify pathogens to control them?) |
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Degree of Human Involvement in the Transmission Cycle
Primary (anthroponosis) – |
Primary (anthroponosis) – disease resulting from a parasite that normally infects humans and one or more anthropomorphic vectors.
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Degree of Human Involvement in the Transmission Cycle
Secondary (zoonosis/ornithosis) – |
Secondary (zoonosis/ornithosis) – diseases of animals or wild birds that occasionally infect humans. Humans are typically not an essential component of the transmission cycle and may become ill, but are “dead-end” hosts.
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Vector Incrimination
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Demonstrate an association in TIME AND SPACE between arthropod and disease
Demonstrate DIRECT CONTACT between the arthropod and humans Demonstrate natural occurrence of the infectious agent in the insect Demonstrate “transmission” of the agent by the insect (LABORATORY-BASED VECTOR COMPETENCE) |
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TO CONTROL MALARIA
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prevent mosquito feeding on humans
prevent or reduce mosquito breeding prevent development of the parasite in the mosquito host destroy mosquito larvae and/or adults eliminate the malaria parasites in the human host educate the human host |
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How to prevent mosquitoes from feeding on humans?
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Personal Protection Measures
Insecticide treated material – nets (LLN) , curtains, hammocks, eave strips, papyrus mats, clothing Pyrethroid insecticides used for treatment Repellents and domestic insecticides (DEET, picaridin, oil of lemon eucalyptus - apply to skin, permethrin – apply to clothing) Coils, vaporizing mats Insecticidal soap/paint |
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How to prevent or reduce mosquito breeding?
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Environmental Management – Destroy Mosquito Breeding Sites
Breeding Site Treatment – Current (larvicidal oils or other surface treatments such as kerosene) |
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How to prevent development of the parasite in the mosquito host?
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Create Vectors Resistant to Malaria Infection - Future
Create a Different Infection (Viral, Bacterial or Fungal?) in Mosquitoes to Cause Death of Malaria Parasite - Future |
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How to destroy mosquito larvae or adults?
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Larval Control (Chemical or Biological) - Current
Adult Control (Chemical or Biological) – Current |
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Larviciding and Biological Control
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Larval control relevant only when a high proportion of the breeding sites within the mosquito flight range of the community to be protected can be located
BTI – Bacillus thuringiensis var. israelensis Bacillus sphaericus (polluted waters, self replicating) Larvivorous fish, copepods, turtles, etc. (larval predators) |
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Adulticiding
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Residual Wall Spraying
Space Spraying (Area Spraying) Ultra Low Volume (ULV) insecticide application from truck or airplane Insecticides: organophosphates, pyrethroids |
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How to eliminate the malaria parasites in the human host?
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Antimalarial drugs (mefloquine, doxycycline, or Malarone™, chloroquine or hydroxychloroquine sulfate) - Current
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Filariasis Control
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Education and Personal Protection from Mosquitoes -determine timing of feeding activity
Mosquito Control – target appropriate species (Culex, Mansonia, Aedes – depends on geographic area) Treatment of Infected Individuals - Mass treatment of at risk population with diethylcarbamazine (DEC) and/or ivermectin and/or albendazole |