Cambridge International A Level Biology Revision Guide

Chapter 10: Infectious diseases
Roll Back Malaria
Malaria is one of the most serious of all human
diseases. It is endemic in about 100 countries in Latin
America, Africa and South-East Asia. An infectious
disease is endemic in a country if it is maintained there
by transmission between people and does not occur
by being brought into the country by travellers. The
burden of malaria is felt most in countries in Africa:
47% of all deaths from malaria occur in Nigeria and the
Democratic Republic of the Congo.
If we are to lift the burden of malaria, then we
have to outsmart this disease. Many international
organisations are cooperating with African
governments to reduce the number of cases of
malaria. For example, Roll Back Malaria is a global
partnership working to implement coordinated action
against malaria. Laboratory research using modern
genetic methods plays an important part, but the
success of new initiatives in the Roll Back Malaria
campaign can only be evaluated by tracking cases of
the disease and collecting accurate data. Technology is
helping here too in pinpointing accurately where cases
occur (Figure 10.1). Find out more by searching online
for ‘roll back malaria’.
Knowing when and where outbreaks occur provides
key data in the fight against infectious diseases. When
an outbreak of malaria occurs, the local population
can be warned to take appropriate precautions to
avoid getting bitten by mosquitoes. These include
sleeping under bed nets and draining any bodies
of water that female mosquitoes might use to lay
their eggs. The local area can be sprayed to kill any
mosquitoes. By tracking when and where malaria
outbreaks occur, health agencies can direct their
resources to control the spread of the disease and limit
its effects on local populations.
Figure 10.1 Modern technology in the fight against malaria:
these health workers in Kenya are using GPS to record
accurate locations where there are outbreaks of malaria.
199
Infectious diseases are diseases that are caused by
organisms known as pathogens. They are sometimes
called communicable diseases as they are passed from
infected to uninfected people. Some also affect animals
and are passed from animals to humans.
In Chapter 9, we considered non-infectious diseases
of the gas exchange and cardiovascular systems, such as
lung cancer and COPD. These are long-term degenerative
diseases. They are non-infectious diseases, as they are not
caused by pathogens. Inherited or genetic diseases, such as
cystic fibrosis and sickle cell anaemia, are another group of
non-infectious diseases. There are other categories of noninfectious
disease, including deficiency diseases that are
caused by malnutrition and mental diseases.
The word ‘disease’ implies something very serious,
yet many conditions that make us feel ill, such as the
common cold, are not as harmful to health as the diseases
discussed in this chapter. ‘Disease’ is a difficult word to
define satisfactorily as it covers a wide range of human
conditions. A working definition is given below.
A disease is an illness or disorder of the body or mind that
leads to poor health; each disease is associated with a set
of signs and symptoms.
As you read this chapter and Chapter 11, you can think of
ways to improve this definition.
QUESTION
10.1 Use Chapter 9 and this chapter to name:
a two infectious diseases and two non-infectious
diseases of the gas exchange system
b two non-infectious diseases of the cardiovascular
system.