Malaria is a disease transmitted by a vector. In 2014, the World Health Organization (WHO) estimated that 3200 million people were at risk of malaria. This was almost half of the world population in 2014. Table 4.1 shows the number of cases of malaria and the number of deaths from malaria between 1998 and 2013. The table shows numbers for all the countries of the world and for the countries in the WHO African region. The table also shows the numbers in the African region as percentages of the numbers for all countries. [Table 4.1]

1. (a)(i)State the name of the pathogen that causes malaria.[1]
2. (a)(ii)State the name of the vector that transmits the pathogen.[1]
3. (b)Describe the trends shown in Table 4.1.[3]
4. (c)Suggest reasons why the number of cases of malaria and the number of deaths from malaria changed between 1998 and 2013.[3]
5. (d)Malaria is very difficult to control even though there is improved understanding of the disease. Explain why malaria is very difficult to control.[4]