Recent research marks the unique factors influencing Zika virus transmission in Africa. A study published in The Lancet Planetary Health reveals that the genomic variation in mosquito populations plays role in the low incidence of the virus on the continent. Conducted by scientists from esteemed institutions, the study focuses on the two forms of the Aedes aegypti mosquito that transmit Zika.
Genomic Variation in Mosquitoes
The Aedes aegypti mosquito exists in two forms. The light-coloured Aedes aegypti aegypti (Aaa) is found mainly outside Africa. It thrives in human habitats and prefers human blood for feeding. Conversely, the dark-coloured Aedes aegypti formosus (Aaf) is native to Africa. This form has a more varied diet, feeding on both humans and animals, which reduces the likelihood of transmitting the virus to humans.
Feeding Preferences and Transmission Capacity
The feeding habits of these mosquito forms are crucial. Aaf, being a generalist, breeds in natural water sources and has a lower capacity to acquire and transmit the Zika virus compared to Aaa. This difference creates a natural barrier, limiting the virus’s spread in Africa.
Impact of Temperature on Zika Transmission
Temperature is another critical factor. The study suggests that while many areas in sub-Saharan Africa have climates conducive to Zika transmission, extreme temperatures can hinder the virus’s spread. The researchers modelled the effects of temperature on mosquito development and survival, indicating that unsuitable temperatures may restrict transmission.
Urbanisation and Future Vulnerability
Rapid urbanisation poses a potential risk for future Zika outbreaks. The study identified 59 urban centres in Africa with populations over one million. Alarmingly, 39 per cent of these cities are already deemed suitable for Zika outbreaks. As cities grow and climate change progresses, the vulnerability to Zika may increase.
Population Genetics and Disease Burden
The research puts stress on the influence of mosquito population genetics on Zika transmission. The presence of Aaa mosquitoes correlates closely with the Zika virus burden across Africa. This genetic variation may have a more impact on transmission than climatic conditions.
Conclusion on Zika Virus Dynamics
The findings from this study provide a nuanced understanding of Zika virus dynamics in Africa. The interplay of mosquito subspecies, temperature, and urbanisation shapes the transmission landscape. As conditions change, monitoring these factors will be essential in managing potential outbreaks.
Questions for UPSC:
- Examine the role of climate change on vector-borne diseases in urban areas.
- Critically discuss the impact of urbanisation on the spread of infectious diseases.
- Point out the differences in breeding habits between Aedes aegypti aegypti and Aedes aegypti formosus.
- Analyse the relationship between mosquito population genetics and the incidence of Zika virus in Africa.
Answer Hints:
1. Examine the role of climate change on vector-borne diseases in urban areas.
- Climate change can alter temperature and precipitation patterns, affecting mosquito breeding and survival.
- Urban areas may experience heat islands, which can create favorable conditions for vector proliferation.
- Increased rainfall can lead to more standing water, enhancing mosquito breeding sites.
- Climate change may shift the geographical distribution of vectors, exposing new regions to diseases.
- Higher temperatures can accelerate the life cycle of mosquitoes, increasing transmission rates of diseases like Zika.
2. Critically discuss the impact of urbanisation on the spread of infectious diseases.
- Urbanisation often leads to overcrowded living conditions, facilitating disease transmission.
- Improper waste management and drainage can create breeding grounds for disease vectors.
- Increased human mobility in urban areas can spread pathogens more rapidly.
- Urban heat islands may support the survival of vectors like mosquitoes, enhancing disease risk.
- Urbanisation can strain public health infrastructure, making it harder to control outbreaks.
3. Point out the differences in breeding habits between Aedes aegypti aegypti and Aedes aegypti formosus.
- Aedes aegypti aegypti (Aaa) breeds primarily in artificial containers like buckets and tires, often found in human habitats.
- Aedes aegypti formosus (Aaf) breeds in natural water sources such as tree holes and rock pools.
- Aaa has a preference for human blood, while Aaf feeds on both humans and animals, reducing transmission risk.
- Aaa is more reliant on human environments, whereas Aaf is a generalist found in diverse habitats.
- The breeding habits of Aaf contribute to a lower capacity for Zika virus transmission compared to Aaa.
4. Analyse the relationship between mosquito population genetics and the incidence of Zika virus in Africa.
- The genetic variation among mosquito populations affects their feeding preferences and transmission capacity.
- Aedes aegypti aegypti (Aaa) mosquitoes are more effective at transmitting Zika compared to Aedes aegypti formosus (Aaf).
- Higher proportions of Aaa in certain areas correlate with increased Zika virus incidence.
- Genetic diversity within mosquito populations may create natural barriers to Zika transmission.
- Population genetics can be more influential than climate factors in determining Zika’s spread in Africa.
