Simón Pierre steps into the surf as day breaks in Kribi, a coastal city in southern Cameroon. He has come to the beach to help pull in fishing nets and bring wooden fishing boats ashore.

This is a daily ritual for Simón, who works two jobs to provide for his six children. After finishing his shift as a night watchman, or security guard, he heads to the beach around 6:00am to bring in the day’s catch alongside other local fishermen and women.

It’s strenuous work that is not without risk. Yet of all the dangers inherent in working overnight, one of the biggest threats comes from a tiny insect: the mosquito. As daylight fades, mosquitoes become more active, biting through the night and into the early morning hours — transmitting deadly diseases like malaria to those unlucky enough to cross their path. 

Simón is not alone. For countless night workers across Cameroon and sub-Saharan Africa, exposure to malaria-carrying mosquitoes is a near-constant threat. 

“We’re talking about fishers, farmers, security guards, miners, gas station attendants, construction workers and many others who are extremely exposed,” says Olivia Ngou, Executive Director of Impact Santé Afrique in Cameroon. 

Malaria risks rise for night workers not only because mosquitoes are active, but because they cannot benefit from gold-standard preventive tools like insecticide-treated bed nets or indoor residual spraying. 

“If you’re sleeping outdoors, it’s difficult to hang a net. If you’re working at night, you can’t just walk around with a net,” says Dr. Carlos Chaccour of the University of Navarra on the barriers to bed net usage outside the home. 

And even one bout of malaria can be financially devastating. As Ms. Ngou explains, missing just one week of work to recover from a single case of malaria can be a massive setback for the entire family. 

“The way they are able to feed their family is through work, they depend on their salary,” she says. Adding, “I’ve met mothers who had to choose which children to send to school. After paying for malaria treatment for a sick family member, there simply wasn’t enough left for school fees.” 

Leaving No Worker Behind in Malaria Elimination Strategies 

Beyond the financial and familial toll of malaria, night workers also represent a critical population for national malaria programs to address as countries work toward elimination.  

Zanzibar, for example, has come tantalizingly close to malaria elimination, reducing prevalence to less than 1 percent. It’s a remarkable achievement made possible by two decades of diligent malaria control efforts. But getting to zero will require closing every remaining gap, and that includes targeting interventions to account for night workers.

“In Zanzibar, where population mobility and construction activities can bring people into areas of malaria transmission, these groups require particular attention,” explains Dr. Shija Joseph Shija, Program Manager, Zanzibar Malaria Elimination Program. 

In fact, a 2023 study found that those who worked as night watchmen or security guards in Zanzibar were more than five times as likely to contract malaria as those working outside the profession, with construction workers and farmers following closely behind. 

“Strengthening access to insecticide-treated nets, combined with other timely testing, effective treatment, and malaria awareness is essential to reducing malaria risk among night workers and other mobile populations,” adds Dr. Shija.

Staying Ahead of the Mosquito

Making sure people are protected from malaria-carrying mosquitoes regardless of their occupation is essential to malaria elimination. But changes in mosquito behavior and the arrival of an invasive, insecticide-resistant species on the Continent are only making it harder to close gaps in coverage. As the use of preventive tools like insecticide-treated bed nets has expanded in recent decades, so too has the selective pressure on mosquitoes. While the majority still prefer to bite in the middle of the night, transmission is shifting outdoors, and more biting is occurring at dusk or dawn — when people are less likely to be inside or under a bed net. 

“Mosquitoes have evolved over millennia,” says Dr. Chaccour. “It’s easier to feed at night when there’s less heat and we’re not able to squash them because we’re asleep.” 

While most malaria-carrying mosquitoes still prefer to bite at night, those that bite outdoors at dusk or dawn have an advantage: feeding without contending with insecticides or bed nets. 

“It’s not that the mosquitoes are learning,” as Dr. Chaccour explains, “we are selecting for those that prefer to bite in the spaces and times not protected by our tools.” 

This is a problem for everyone, not only night workers. Anyone who is outside at dusk, whether finishing work or visiting with family and friends, or simply heading to work or school early in the morning, are increasingly at risk of contracting malaria. 

Recent years have also seen the arrival and rapid spread of Anopheles stephensi across the Continent. First reported in Djibouti in 2012, this invasive species of mosquito arrived from South Asia and the Arabian Peninsula. It has since been confirmed in ten countries — and counting — putting 126 million people in African cities at risk. 

“These mosquitoes are not necessarily strict night feeders,” notes Dr. Chaccour. “They are a triple threat: they are resistant to insecticides, they can thrive in urban environments, and there’s a problem of residual transmission.” 

Getting ahead of the threat posed by An. stephensi will take increased investment in surveillance and the rapid deployment of new tools and technologies. 

“We want a one size fits all solution,” says Dr. Chaccour. “We need to recognize that our tools will always have holes, but if we layer them, we can have a greater impact.” 

The good news is that new malaria tests, treatments, and vaccines are rapidly becoming available alongside advanced surveillance and vector control tools. Many of these innovations are being led by American companies, reinforcing a layered approach to malaria control and   elimination. 

One such product, which Ms. Ngou calls a “breakthrough,” was pioneered by SC Johnson: a new spatial repellent that is smaller and easier to hang than a bed net. Through a partnership between the U.S. Department of State and the Global Fund to Fight AIDS, Tuberculosis and Malaria, SC Johnson is distributing Guardian™ devices in malaria-endemic countries. 

Malaria elimination will require meeting people where they are, targeting interventions to account for vulnerable groups and innovating past barriers to stay ahead of the threat. That will take sufficient resourcing — now, not later.  

“Our enemy, the mosquito, is not waiting for us,” as Ms. Ngou explains. “It will continue to evolve so we have to be faster and better. We need to increase funding to get rid of this disease once and for all because if we don’t, we will have a much bigger malaria problem than the one we have now.”