A groundbreaking 22-year study has unveiled the effectiveness of mosquito nets, finding that the relatively inexpensive malaria prevention equipment can significantly increase a child’s chances of reaching adulthood.
The study, led by experts from Ifakara Health Institute (IHI), the London School of Hygiene & Tropical Medicine (LSHTM), and the Swiss Tropical and Public Health Institute (Swiss TPH), was conducted in Tanzania. The researchers found that children who slept under mosquito nets from an early age were considerably more likely to survive into adulthood.
The investigation analysed over 6,700 children between 1998 and 2019, showing that regularly sleeping under mosquito nets increased the chances of reaching adulthood by 40% compared to those who did not.
The study is published in the New England Journal of Medicine.
The devastation imposed by malaria
Malaria is a severe disease that is caused by parasites transmitted when the female Anopheles mosquito bites people. Estimates from the World Health Organization (WHO) shockingly signify that in 2020, around 241 million people had malaria globally, resulting in 627,000 deaths. Currently, 95% of malaria cases and 96% of malaria deaths occur in the WHO African Region, with 80% of these deaths attributed to children under five.
Prior to this investigation, there were very few long-term population-based studies in an African country, meaning the effects of malaria control over a long period was unknown; now, this study provides unprecedented insights into the longstanding benefits of mosquito nets for mitigating malaria.
Earlier theories not related to this study suggested that preventing malaria in children would make them more susceptible to the disease later in life due to a lack of immunity, only delaying the life-threatening illness and death. However, the team’s novel findings discovered no correlation between early prevention in life and a surge in deaths in adulthood.
Dr Salim Abdulla, the Principal Scientist at IHI and study author, said: “We have known for a long time that bed nets save young lives, but we never knew for sure how long the benefits persisted. Our study shows that preventing malaria in early childhood has effects that last into adulthood.”
The performance of mosquito nets
Between 1998 and 2003, the team enrolled 6,706 children born in the rural Tanzanian districts of Kilombero and Ulanga, locations where malaria is endemic. A survey team visited the children’s houses every four months, collecting data about the use of mosquito nets. 16 years later, in 2019, the team returned to perform a follow-up survey, collecting information on 5,983 (89%) of the original participants. Sadly, 600 of the children died during the study period.
Analysis revealed a positive long-term effect of mosquito nets, estimating a correlation between their use and survival by employing regression modelling to adjust for other differences between groups.
Dr Günther Fink, Associate Professor of Epidemiology and Household Economics at the University of Basel and Swiss TPH, and first author, said: “It’s so important to be able to go back and find out what happens to children when they grow up. Bed nets have been a huge part of malaria control efforts and continue to be part of the toolkit. It is reassuring to see these long-term benefits, which further highlight the remarkably high returns to investing into early childhood infectious disease prevention and early life health more generally.”
Dr Joanna Schellenberg, Professor of Epidemiology and International Health at LSHTM and last author on the paper, said: “It’s remarkable that we were able to find information on nearly all these children born two decades ago. While our study shows the survival benefit of early-life malaria control persists until adulthood, it also reveals the potential of long-term community-based research. It’s a testament to the deep social connections the interviewers had in the study communities, as well as making the most of mobile phone coverage.”
Co-author Mr Sigilbert Mrema, a Research Scientist with IHI, said: “One of our respondents was overjoyed simply to be told his exact date of birth. This type of long-term study is important not only in monitoring health but also in strengthening civil registration.”
The team stated that a limitation of their study is that there was no data available for the children who died before the first study visit, meaning survival rates are not representative of all births.
