HLT 555 Module 4 Discussion 1
How do vectors play a role in the transmission of disease? What are some procedures for control and prevention? Provide a specific example.
A vector is a living organism that transmits an infectious agent from an infected animal to a human or another animal. Vectors are frequently arthropods, such as mosquitoes, ticks, flies, fleas and lice.
Vectors can transmit infectious diseases either actively or passively:
- Biological vectors, such as mosquitoes and ticks may carry pathogens that can multiply within their bodies and be delivered to new hosts, usually by biting.
- Mechanical vectors, such as flies can pick up infectious agents on the outside of their bodies and transmit them through physical contact.
Diseases transmitted by vectors are called vector-borne diseases. Many vector-borne diseases are zoonotic diseases, i.e. diseases that can be transmitted directly or indirectly between animals and humans.
What are the methods of vector control?
Vector control involves using preventive methods to eradicate or control vector populations, in order to
limit the transmission and spread of diseases. Preventative measures include:
• Habitat control: Removing or reducing the number of places where the vector can breed helps to
limit populations from growing excessively. For example, by removing stagnant water, removing old
tires and empty cans which serve as mosquito breeding habitats and through good management of
• Reducing contact with vectors: Reducing the risk of exposure to insects or animals that are vectors
of diseases can limit the risk of infection. For example, using bed nets, adding window screens to
homes, or wearing protective clothing can help reduce the likelihood of coming into contact with
vectors. An important component of exposure reduction is also the promotion of health education
and raising awareness of risks. Bed nets treated with insecticide can reduce the risk of insect bites
• Chemical control: Insecticides, larvicides, rodenticides and repellents are used to control pests and
can be used to control vectors. For example, larvicides can be used in mosquito breeding zones;
insecticides can be applied to house walls (indoor residual spraying); bed nets treated with
insecticide and use of personal skin repellents can reduce the risk of insect bites and thus infection.
The use of pesticides for vector control is supported by the World Health Organization (WHO) and
has proven to be highly effective.
• Biological control: The use of predators (natural enemies of the vectors), bacterial toxins or
botanical compounds can help control vector populations. For example, using fish that eat mosquito
larvae or the introduction of sterilized male tsetse flies in order to reduce the breeding rate of these
flies are methods to control vectors and reduce the risk of infection. HLT 555 Module 4 Discussion 1