Diabetes and obesity were significant risk factors for severe infection among nonimmune travelers and immigrants from malaria endemic countries, according to researchers.
“Obesity and noncommunicable diseases (NCDs), such as diabetes, hypertension and cardiovascular disease, increase globally, including in malaria-endemic regions,” Katja Wyss, MD, of Karolinska Institutet and the departments of emergency medicine and infectious diseases at Karolinska University Hospital, Stockholm, Sweden, and colleagues wrote in Clinical Infectious Diseases. “In addition, a significant proportion of travelers are older, and an estimated third of travelers to malarious countries have underlying medication conditions. This changing disease panorama in populations at risk of malaria warrants the need to establish how comorbidities affected severity of malaria.”
The researchers conducted a nationwide observational study of imported malaria infections in Sweden over a 20-year period from January 1995 to May 2015 to assess whether NCDs were associated with severe infection with Plasmodium falciparum. The analysis included 937 adults with malaria, representing 71.9% of all P. falciparum cases reported in Sweden during the study period.
Using data from patients’ medical records and travel history, the researchers determined that 58.4% of patients originated from Sub-Saharan Africa, 80.6% were Swedish residents and 17.9% recently immigrated to or were temporarily visiting the country. The majority of malaria infections were acquired in Western and Eastern Africa.
Severe malaria infections occurred in 9.8% of patients and one death was reported, yielding a case fatality rate of 0.1%. Patients with severe infection had a higher prevalence of chronic conditions (30.4% vs. 17.9%; P = .0004), a higher median BMI (29.3 vs. 24.7; P < .0001), and were more likely to be obese (21.8% vs. 4.5%; P < .0001) vs. those with nonsevere infections. A multivariable analysis showed that having two or more chronic diseases (adjusted OR = 2.49; 95% CI, 1.10-5.68), a Charlson score of one or greater (aOR = 2.63; 95% CI, 1.45-4.77), and diabetes (aOR = 2.98; 95% CI, 1.25-7.09) were associated with an increased risk for severe infection. Obesity was also highly associated with severe infection, both independently (aOR = 5.58; 95% CI, 2.03-15.36) and in addition to another metabolic risk factor such as hypertension, dyslipidemia or diabetes (aOR = 6.54; 95% CI, 1.89-22.88). The findings were similar among nonimmune travelers and immigrants.
“Obesity and diabetes are well recognized to increase severity of infections,” the researchers wrote. “Both conditions are characterized by low-grade chronic inflammation and altered levels of nutrients and metabolic hormones with immunomodulatory effects. Equally important, metabolic changes could have specific effects on the malaria parasite and pathogenesis.”
Wyss and colleagues concluded that their findings may have implications for managing malaria infection among travelers in Sweden as well as patients in Sub-Saharan Africa, where there is an increasing prevalence of comorbidities that may make the population more vulnerable to severe infection.
“This is to our knowledge the first study investigating the impact of NCDs on severity of P. falciparum malaria,” they wrote. “The findings are of high clinical relevance for the acute management of malaria in travelers and there is an urgent need for awareness and further investigations of these risk factors also in malaria-endemic areas.” – by Stephanie Viguers
Disclosure: The researchers report no relevant financial disclosures.