Explain how climate change is predicted to affect the geographic distribution of vector-borne diseases such as malaria.

IB DP Biology Higher Level (2023 syllabus) — D4.3 Climate change · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Rising global temperatures and altered precipitation patterns associated with climate change are projected to shift the habitats of disease vectors, with significant implications for human health.

Model answer (4 marks)

Rising temperatures allow Anopheles mosquitoes to survive and reproduce at higher altitudes and latitudes than previously possible, expanding the range of malaria.
Warmer temperatures shorten the extrinsic incubation period of Plasmodium within the mosquito, so the parasite matures faster and transmission potential increases.
Altered precipitation patterns – for example, increased rainfall or flooding – create more standing water, expanding breeding habitats for the vectors.
Populations in these newly affected regions lack immunity to malaria, so morbidity and mortality are expected to rise there.

Examiner tips

  • Use the exact terms ‘extrinsic incubation period’ and ‘Anopheles mosquitoes’. Show the causal chain: temperature → vector survival, temperature → incubation period, rainfall → breeding sites, lack of immunity → higher disease burden. Keep the answer concise – one sentence per point – to hit all four marks.
  • common_mistakes
  • :
  • Mixing up intrinsic and extrinsic incubation periods. Using vague phrases like ‘more mosquitoes’ instead of specifying Anopheles. Omitting the immunity/vulnerability point or the link to morbidity/mortality.

Mark scheme (4 marks)

  1. Rising temperatures allow disease vectors (e.g. Anopheles mosquitoes) to survive and reproduce at higher altitudes and latitudes than previously possible.
  2. Warmer temperatures shorten the extrinsic incubation period of the pathogen within the vector, increasing transmission potential.
  3. Altered precipitation patterns (increased rainfall or flooding) create more standing water, expanding breeding habitats for vectors.
  4. Populations in newly affected regions lack immunity to the disease, making them more vulnerable, so morbidity and mortality are expected to increase in those areas.

Key terms in this question

vector-borne disease · vector · geographic distribution

Related

More Climate change questions

▶ Try answering this question with AI marking (free) →