Vector control measures

Many tools for arthropod control are found in today’s arsenal with their own

advantages and drawbacks. In this section some of the major approaches that

have been used to control vectors and some that show promise for the future are

presented:

(1) Mechanical methods

E.g. Use of bed nets, wire mesh, etc.

(2) Ecological control

Ecological control procedures involve the removal, destruction,

modification, or isolation of materials that might favor the survival of an

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insect pest by affording food or making a site suitable for breeding and/ or

dormancy. e.g. draining marshy areas.

(3) Chemical methods

Deals with the use of natural or synthetic chemicals that directly cause the

death, repulsion, or attraction of insects. E.g. use of DDT

(4) Biological methods

Refers to the regulation of vector population using predators, like certain

species of fish, which feeds on larval stages of some arthropods, and

microbial agents. There are several advantages in using biological control

agents. Unlike pesticides, biological control agents are safe to use and do

not pose any threat to the environment.

(5) Genetic control

Involves manipulation of the mechanisms of heredity. In some research

centers sterilized male mosquitoes are used in order for them to compete

with natural ones and thereby decreasing the new generation of

mosquitoes.

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SUMMARY

Medical entomology is a science that deals with the study of arthropods, which

play a significant role in the transmission of a number of diseases to humans.

Arthropods affect the health of man by being either direct agents for disease or

discomfort or agents for disease transmission. In mechanical carriers the

pathogen does not multiply in the arthropod whereas the arthropod is an integral

part of the life cycle of the pathogen in biological carriers.

The three medically important Classes of Arthropods are the Class Insecta,

Crustacia, and Arachnida, which have their own distinguishing features. A clear

understanding of the classification and characteristics of each of the classes is to

paramount importance in devising ways of control the vectors.

LEARNING ACTIVITY

Answer the following questions.

1) List the general features of all arthropods.

2) Discuss the circulatory system of arthropods.

3) List the direct effects of arthropods on humans.

4) Discuss the different types of biological carriers giving examples.

5) Explain the medical conditions related to arthropods.

6) List the different approaches in the control of vectors.

REFERENCES

Nabil Nassr, Review of human parasitology, 2nd ed.

Romosor William, The science of entomology, 1998, 4th ed.

Chapman and Hall, Medical entomology, 1996

Rchards O imms, General textbook of entomology, 10th ed.

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GLOSSARY

Autoinfection: self infection

Chyluria: lymphatic fluid

Definitive host: An animal that harbors a parasite where it reaches sexual

maturity in or on it.

Gynecophoral canal: This is a canal in the male schistosome where the adult

female worm is carried.

Haematuria: Presence of blood in the urine

Hermaphrodite: having both sexes in one

Intermediate host: Hosts normally infected with certain parasites, which are also

capable of infecting humans.

Molluscicide: Chemical used to kill snails

Proglottid: a unit of tapeworm body