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#WorldMalariaDay: can nets and sprays keep the bugs away?

By Abraar Karan MD, Harvard T.H. Chan School of Public Health

Many nights, I wondered what was worse: risking a bite from one of the many Anopheles mosquitos flying around my room, or suffering another day sleep-deprived and exhausted? I’ll admit that I was close—very close—to throwing the mosquito net out altogether as I crawled underneath it each evening, ready for another bout of tumbling and turning in the claustrophobic, heat-catching device.

This same device has saved millions of people worldwide from vector-borne diseases such as malaria, Zika, dengue, and more. On World Malaria Day 2017, I can’t help but recall the many global health voyages I have taken to India, Sub-Saharan Africa, Southeast Asia, and Latin America, the regions of the world in which malaria is a daily plague.

In 2015 alone, there were 212 million cases of malaria and 438,000 deaths. 90% of these occurred in Africa. While malaria funding totaled $2.9 billion in 2015, the parasite continues to kill our youngest and most vulnerable: 7 out of 10 deaths occur in children under the age of 5, who often die of cerebral malaria. So what do we do?

As I mentioned, sleeping under a bed-net is not the panacea it has been touted to be. In one study, participants complained of the smell of insecticide, itching and dizziness, not to mention that nets were sometimes misused for catching animals or fish. Furthermore, nets were effective for only 6 months (regardless of optimal use), or between just 2 and 3 washes, after which they were at higher risk of tears or holes through which mosquitos could enter.

Image credit: Scott Chacon, flickr. Woman receiving a donated mosquito net in Kisumu, Kenya

Imagine the life of a villager in Sub-Saharan Africa. If she is one of the 53% that use nets daily, her day will begin underneath a safe blanket of mesh. But from there, she is constantly at risk of a mosquito bite throughout the day. Solutions have primarily focused on keeping the home insect-free, via indoor residual insecticide, outdoor aerial spraying, and the use of coils, mats and other repellents that remain in the house. However, given many villagers in these regions are subsistence farmers, they are in dire need of adequate malaria prevention while working outside, often near stagnant water and mosquito breeding grounds. Traditional mosquito repellents are expensive, wash off with sweat from the skin, and are undermined further because of mosquito resistance. Additionally, people have poor adherence to repellents because of their need for continuous reapplication—studies have found usage to be as low as 8% even when participants were given repellent for free.

Malaria prevention has been a multifold effort that requires a combination of vector-elimination and host-protection. For foreigners visiting malaria-endemic regions, there are a number of medications that are commonly used. However, some of the most common ones have significant drawbacks, including side-effects of psychosis, requirements of minimal sun exposure, or the commitment of taking a daily pill that can pose adherence challenges. Also, many mosquitos have begun developing significant resistance to the existing drug compounds such as DEET.

The elimination of mosquitos has been a strategy that has been pursued with some notable success. Recently, bacteria-infected lab mosquitos were released in Florida to attempt to kill Aedes mosquitos that carry Zika Virus. Furthermore, gene-edited mosquitos that are unable to transmit the malaria parasite are currently undergoing field-testing. Environmental modifications, such as removing stagnant water sources and reducing outside waste accumulation are particularly difficult in contexts wherein which infrastructure is already limited, such as many rural regions of the world. Larvicides have been proven in recent trials to provide strong vector control, but still need to be trialed in larger-scale studies.

Despite the complexity of malaria control and elimination, immense progress has been made. From 2010 to 2015, malaria incidence rates have decreased by nearly 21%, and mortality rates by 29%. The most advanced malaria vaccine, RTS,S, has already begun field trials as of November 2016, with previous data showing vaccine efficacy of 27% to 39% in infants and children up to 17 months. With continued funding support from a number of large agencies, including the Gates Foundation, Global Fund, and USAID, we will continue to push back the tide against malaria.

Until then, I will have to learn to love my mosquito net.

[Featured image top: Barry Pousman]

Dr. Abraar KaranDr. Abraar Karan, Harvard T.H. Chan School of Public Health

Dr. Abraar Karan is an MPH candidate at the Harvard T.H. Chan School of Public Health, and a graduate of the UCLA David Geffen School of Medicine. Dr. Karan is the editor of the book, Protecting the Health of the Poor: Social Movements in the South. He has worked in Uganda and Mozambique on efforts related to the political dynamics of the HIV/AIDS epidemic.

Dr. Karan’s last posts in PLOSBLOGS: A Call for Courage in Uncertain Times: Curbing HIV/AIDS in Sub-Saharan Africa through Political Leadership and Why Mentors Matter: Global Health Research Mentorship in LMICs

Opinions expressed in this guest post reflect the views of its author and are not necessarily shared by PLOS or the PLOS journals.

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