Introduction

Diseases

Most human diseases are caused by pathogens that are found in our environment. Pathogens live in the soil, air, water and contaminated food. Pathogens in our environment may enter our bodies through the mouth, nose, skin and genitals. Some human diseases are transmitted through touching or by agents called vectors. Vectors transmit pathogens such as bacteria, viruses, fungi and parasites. For example, female mosquitoes (Anopheles) carry malaria parasites called Plasmodium. The parasite is introduced into the human body when a mosquito bites an individual.