Chapter 1: General Information on Mosquito-Borne Diseases

Welcome to the World Health Organization’s (WHO) Pacific Open Learning Health Net (POLHN) interactive learning module on mosquito-borne diseases. This module is designed for you, as a health worker, to better understand the three most common diseases spread by mosquitoes and to provide health education for different audiences. It uses simple, non-technical language that you can easily adapt for your presentations to schools, community groups, and others.

Health educators can act as “translators” or bridges to promote awareness, knowledge, and tolerance. You understand cultural and community standards as well as the science of diseases and the importance of prevention. Using this understanding, you can create educational messages that are both scientifically accurate and culturally acceptable.

This learning module on mosquito-borne diseases is organized into chapters, like an electronic book. This chapter provides an introduction to the different diseases. The following chapters provide information about preventing the diseases (Chapter 2), a discussion of complications and treatment options (Chapter 3), useful resources for different audiences (Chapter 4), and a sample presentation and tips for giving your own presentations (Chapter 5).

You can either read through from start to finish or move around to the sections you need. The top navigation bar lists the five chapters in the module; when you select a chapter, the lower navigation bar lists the sections within the chapter. Sections on dengue come before those on filariasis and malaria within each chapter; the arrow indicates where you are. To switch between them, click on the linked words (Dengue, Filariasis, or Malaria). Use the bar in the middle of the page to scroll down as you read. To print the chapter, click on the computer icon below the scroll bar.

Each chapter sets learning goals and provides links to guide you to related resources and further information. Click on the colored and underlined text to follow these links. Most chapters conclude with a ‘Learn More’ section with links, a glossary of terms, and a list of resources with their website addresses.

We hope this learning module proves useful to you, and we thank you for your dedication to improving the health of communities in the Pacific. If you would like more copies of the module, or if you have suggestions, questions, or comments about it, please contact Dr. Richard Wah, WHO South Pacific Office, P.O. Box 113, Suva, Fiji (email: WahR@sp.wpro.who.int).

Learning Goals for Chapter 1

After reading this chapter, you will have a general understanding of:

  • How mosquito-borne diseases are spread to humans
  • The characteristics of dengue, filariasis, and malaria
  • How prevalent these diseases are in the Pacific
  • The risk signs and symptoms of these diseases

Mosquitoes and the Disease Cycle
Dengue, filariasis, and malaria are called mosquito-borne diseases because mosquitoes spread the disease from an infected person to a non-infected person. These diseases move from humans to mosquitoes in a disease transmission cycle. This cycle has four basic steps:

  1. The cycle begins when a person is infected by a pathogen, such as a virus or parasite. This person is called the reservoir host because the virus or parasite lives and multiplies inside the host’s body.
  2. When a female mosquito bites the infected person, it gets the disease through the person’s blood.
  3. Later on, when the infected mosquito bites other people, the pathogen is passed on to them through the mosquito’s saliva. The mosquito is sometimes called a vector.
  4. The people who were bitten get infected and then become reservoir hosts who can pass the infection on through other mosquitoes.

Unless broken by prevention or treatment, this cycle can go on to spread disease throughout the population.

(WHO/Roll Back Malaria Project [RBM], n.d.)