Disease Control - Vector Borne Diseases

Front 1

Types of Vector-Borne Transmission
Mechanical Transmission

Back 1

Mechanical Transmission – simplest form
(not necessary for pathogen survival – “flying/crawling hypodermic needle” phenomenon)

Front 2

Types of Vector-Borne Transmission
Biological Transmission

Back 2

Biological Transmission – more complex
(necessary for pathogen survival – results in amplification or development in vector)

Front 3

Types of Vector-Borne Transmission
What are the types of Vertical Transmission

Back 3

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)

Front 4

Types of Vector-Borne Transmission
What are the types of Horizontal Transmission

Back 4

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.

Front 5

Horizontal Transmission Types

Back 5

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

Front 6

Extrinsic Incubation Period - EIP

Back 6

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.

Front 7

Ecological Parameters Affecting Vector Populations:

Back 7

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?)

Front 8

Degree of Human Involvement in the Transmission Cycle
Primary (anthroponosis) –

Back 8

Primary (anthroponosis) – disease resulting from a parasite that normally infects humans and one or more anthropomorphic vectors.

Front 9

Degree of Human Involvement in the Transmission Cycle
Secondary (zoonosis/ornithosis) –

Back 9

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.

Front 10

Vector Incrimination

Back 10

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)

Front 11

TO CONTROL MALARIA

Back 11

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

Front 12

How to prevent mosquitoes from feeding on humans?

Back 12

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

Front 13

How to prevent or reduce mosquito breeding?

Back 13

Environmental Management – Destroy Mosquito Breeding Sites

Breeding Site Treatment – Current
(larvicidal oils or other surface treatments such as kerosene)

Front 14

How to prevent development of the parasite in the mosquito host?

Back 14

Create Vectors Resistant to Malaria Infection - Future
Create a Different Infection (Viral, Bacterial or Fungal?) in Mosquitoes to Cause Death of Malaria Parasite - Future

Front 15

How to destroy mosquito larvae or adults?

Back 15

Larval Control (Chemical or Biological) - Current
Adult Control (Chemical or Biological) – Current

Front 16

Larviciding and Biological Control

Back 16

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)

Front 17

Adulticiding

Back 17

Residual Wall Spraying
Space Spraying (Area Spraying)
Ultra Low Volume (ULV) insecticide application from truck or airplane
Insecticides: organophosphates, pyrethroids

Front 18

How to eliminate the malaria parasites in the human host?

Back 18

Antimalarial drugs (mefloquine, doxycycline, or Malarone™, chloroquine or hydroxychloroquine sulfate) - Current

Front 19

Filariasis Control

Back 19

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