Vector Control

• The vector is the direct cause of the disease and is often transmitted through contact, from one person to the other.
• Examples include scabies & pediculosis
• Infected vector inoculate the infective agents from its salivary secretions into new host.
• Host become infected through contamination of his mucous membrane or skin by infected faeces of the vector
• Through contamination by infective tissues fluids which are released when the vector is crushed

• This occurs when vector provides a site multiplication or development of infectious agent E.g. rat flea for plague and anopheles mosquito for malaria parasite
• Sometimes, the vector only serves for the development into infective stage of the disease agent, without increase in number of agent, as is the case with the filarial parasite in Culex mosquito, and the guinea worm embryo in Cyclops.
• In some instances, the vector may acquire infection congenitally by transovarian passage e.g. Chagas disease

• This takes place when the vector only serves as a carriage of infectious agent from one source to the next host.
• Vectors carry infective agents on its body or limbs. Infective agents may be ingested by the vector and passes unmodified and excreted in feaces.
• Vectors like housefly serve as mechanical vectors for the transmission of diseases like diarrhoea and trachoma.

• Use of protective barriers e.g. window nets, ITN, protect clothing and equipment
• Insect repellant

• Insecticides are commonly used both for agriculture and household purposes.
• Most of these chemicals can be toxic to man, animal and plants
• Modes of action are basically through knock down or residual effects

Qualities of good chemical for insecticides

• Simple to handle
• Cheap and effective
• Minimal toxic effects on man, animals and plants / crops
• Have a long span of action
• Not affected by physical factors that will decompose it (like light, heat, PH etc)

INSECTICIDES are commonly grouped into two (2)

• Knock down insecticides
• Residual insecticides

Knock down/immediate acting insecticides

• Act by knocking down the insects into stupor and lead to deaths of the insect, or may not kill the insect
• Act fast or immediately
• Actions can be improved by adding residual insecticides
• Insecticides in this category normally contain pyrethrum or Alletrium

Residual insecticides

• Has long continued effect (6 months or more)
• Insect may die rapidly or after some time
• Two groups
• Chlorinated Hydrocarbon: examples are Di-Chlor-Diphenyl Trichloro-ethene (DDT), Benzyl Hexa-Chloride (BHC) & Dieldrin (Dieldrin is much toxic than others)
• Organophosphate: examples are Diazinon, Malethion, Parathione, Diclovos. Organophosphates are very toxic, Expensive and not easy to administered

Disadvantages of use of insecticides

• Insects developed resistance to insecticides
• Residual insecticides are toxic to plant, animal
• Possibility of damage to wildlife and benefits for increasing food production

Methods of application of insecticides are through

• Aerosols, fogs, vapours and smokes.
• Aerial spraying / droppings
• Water dispersible powder and solutions & emissions.

• Indoor residual spraying & long lasting insecticide treated nets

• Control measures are designed to restrict development of insect pests.
• Exposing the insect pest to predators and parasites (biological agents have been investigated for control of arthropod pests)
• Genetical: use of genetic engineering

• This refers to measures taken to reduce or eliminate breeding sites of a vector.
• This include Environmental modification & manipulation.
• It involves alterations in the shelter and food supply through physical changes such as drying of pond or alteration in the speed and course of river.