Mosquito-Borne Disease Prevention

With the weather turning up this summer, so too is the presence of mosquitoes around the home.

Aedes aegypti and Aedes albopictus are two species of mosquitoes that are of particular concern as they have the potential to spread viral infections including Zika virus, yellow fever, dengue, Murray Valley encephalitis, Barmah Forest virus, Ross River virus, and chikungunya (Weeratunga et al. 2017).

One of the most common and wide-spread mosquito-borne diseases is malaria.

Malaria is caused by Plasmodium parasites, that are transmitted via the adult anopheline mosquitoes (Walshe et al. 2013).

Whilst malaria can be contracted in many areas around the world, it is a particularly dangerous issue in sub-Saharan Africa (Tusting et al. 2013). It is believed that as much as 40% of the world’s population live in malaria-affected regions (Polec et al. 2015).

Prevention Strategies for mosquito-related infections involve:

1. Vaccinations to improve the immunity of hosts
2. Vector control (e.g. insecticides, larvivorous fish, genetic strategies, larvae traps and more.)

Vaccination Prevention Strategies

High-quality evidence shows that malaria chemoprevention for ladies in the first or second trimester of pregnancy helps to avoid moderate to severe anaemia (Radeva-Petrova et al. 2014).

This chemoprevention also might make malaria illness less likely, and there is moderate evidence indicating that malaria chemoprevention betters the birthweights of infants (Radeva-Petrova et al. 2014).

Vector Control Prevention Strategies

Tusting et al. (2013) describe that some malaria prevention strategies can involve indoor netting that has been treated with insecticides, and indoor residual spraying.

Other strategies may involve limiting habitats available for larvae (Tusting et al. 2013).

Examples of this could involve draining land, or encouraging waters to be flowing instead of standing still. Moderate quality evidence implied that larval source management (LSM) likely prevents malaria development and infection (Tusting et al. 2013).

‘LSM was shown to be effective in Sri Lanka, India, the Philippines, Greece, Kenya, and Tanzania, where interventions included adding larvicide to abandoned mine pits, streams, irrigation ditches and rice paddies where mosquitos breed, and building dams, flushing streams, and removing water containers from around people’s homes. In one study from The Gambia where mosquitos were breeding in large swamps and rice paddies, spraying swamps with larvicide using ground teams did not show any benefit.’ – Tusting et al. (2013).

Other Factors

Benelli (2015) highlights that some vector control chemicals have adverse health outcomes for humans. Furthermore, the chemicals may also impact on the environment and may also lead to resistance.

Benelli (2015) states that some safer mechanisms for vector control include using mosquitocidals that are plant-borne and ‘sterile insect technique’.

Further Research

It is important that further research into malaria prevention continues, as malaria can lead to illness and/or death (Tusting et al. 2013).

Benelli (2016) states that other strategies to consider may be: lure-and-kill, pheromone traps, and sound traps. Additional research may be needed into the cues for swarming and mating of mosquitoes (Benelli 2016).

One novel strategy for malaria prevention is the ‘Larvivorous fish’. These fish are to be placed in waters (e.g. ponds) near communities so that the fish may eat the mosquito larvae or pupae; thus, preventing the transmission of Plasmodium parasites (Walshe et al. 2013).

However, the study concluded that there was not enough evidence to indicate whether the larvivorous fish strategy lessens the spread of malaria or the adult anopheline mosquito population (2013).

Conclusion

Whilst reducing the number of mosquitoes (such as the aegypti) is important to prevent the spread of infections such as malaria, Dengue, Zika Chikungunya and Yellow Fever viruses, it is essential to consider the cost and effectiveness of implementing vector control strategies in comparison to the benefits (Yakob & Walker, 2016).

References

• Augustincic Polec, L, Petkovic, J, Welch, V, Ueffing, E, Tanjong, Ghogomu, E, Pardo Pardo, J, Grabowsky, M, Attaran, A, Wells, GA & Tugwell, P 2015, ‘Strategies to increase the ownership and use of insecticide-treated bednets to prevent malaria’, Cochrane Database of Systematic Reviews 2015, iss. 3, viewed 2 February 2018, http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD009186.pub2/abstract
• Benelli, G ‘Researcg in mosquito control: current challenges for a brighter future’, Parasitology Research, vol. 114, no. 8, pp. 2801-5, viewed 2 February 2018, https://link.springer.com/article/10.1007%2Fs00436-015-4586-9
• Benelli, G 2016, ‘Spread of Zika virus: The key role of mosquito vector control’, Asian Pacific Journal of Tropical Biomedicine, vol. 6, no. 6, pp. 468-71, viewed 2 February 2018, https://www.sciencedirect.com/science/article/pii/S222116911630291X
• Govindarajan, M, Rajeswary, M, Veerakumar, K, Muthukumaran, U, Hoti, SL, Mehlorn, H, Barnard, DR & Benelli, G 2016, ‘Novel synthesis of silver nanoparticles using Bauhinia variegata: a recent eco-friendly approach for a mosquito control’, Parasitology Research, vol. 115, no. 2, pp. 723-33, viewed 2 February 2018, https://link.springer.com/article/10.1007%2Fs00436-015-4794-3
• Radeva-Petrova, D, Kayentao, K, ter Kuile, FO, Sinclair, D & Garner, P 2014, ‘Drugs for preventing malaria in pregnant women in endemic areas: any drug regimen versus placebo or no treatment’, Cochrane Database of Systematic Reviews 2014, iss. 10, viewed 2 February 2018, https://www.ncbi.nlm.nih.gov/pubmed/25300703
• Tusting, LS, Thwing, J, Sinclair, D, Fillinger, U, Gimnig, J, Bonner, KE, Bottomley, C & Lindsay, SW 2013, ‘Mosquito larval source management for controlling malaria’, Cochrane Database of Systematic Reviews 2013, iss. 8, viewed 2 February 2018, https://www.ncbi.nlm.nih.gov/pubmed/23986463
• Walshe, DP, Garner, P, Abdel-Hameed Adeel, AA, Pyke, GH & Burkot, T. ‘Larvivorous fish for preventing malaria transmission’, Cochrane Database of Systematic Reviews 2013, iss. 12.
• Weeratunga, P, Rodrigo, C, Fernando, SD, Rajapakse, S 2017, ‘Control methods for Aedes albopictus and Aedes aegypti(Protocol)’, Cochrane Database of Systematic Reviews 2017, iss. 8.
• Yakob, L & Walker, T 2016, ‘Zika virus outbreak in the Americas: the need for novel mosquito control methods’, The Lancet: Global Health, vol. 4, no. 3