Neglected tropical diseases (NTDs) are caused by a diverse group of pathogens currently affecting more than one billion people in tropical and subtropical regions. In these regions, coinfections are common between both NTDs and NTDs with non-NTDs such as HIV, malaria, tuberculosis, or other bacterial infections and there is evidence that coinfection with NTDs exacerbates disease in HIV, TB, and malaria in infected populations. For instance, helminth parasites extensively modulate the immune response to allow long-term survival in the host and this immunomodulation not only affects the parasite itself, but also extends to other pathogens potentially influencing the clinical outcome. Despite increased efforts to understand NTDs individually, studies of the immunological, epidemiological, and clinical aspects of NTD coinfections remain scarce. The burden of NTD coinfections disproportionately affects communities with existing health and socioeconomic inequalities and may have life-long effects on health outcomes when experienced in early life. Collectively NTD coinfections present a complex clinical picture, which is poorly understood and pose a challenge to researchers. A better understanding of NTD coinfections and their underappreciated global health burden is required to effectively meet international health and development goals.

This special issue aims to invite high quality original research papers, clinical studies as well as reviews, which contribute to our understanding of coinfections with multiple NTDs or with NTDs and other types of pathogens causing non-NTDs such as HIV, malaria, or tuberculosis in tropical and subtropical regions. Such articles could address specific research challenges posed by coinfections (e.g., diagnostic methods, biomarker identification, quantifying population burden, and identifying risk factors) as well as those, which characterize clinical outcomes for affected populations. We would particularly welcome papers, which address the mechanistic basis for poor health outcomes, even if they are not yet completely conclusive.

Potential topics include but are not limited to the following:

• Epidemiological patterns of coinfections
• Modulation of immune responses by coinfections
• Diagnostic methods and systemic biomarkers in coinfections
• Effects of coinfections on host morbidity and mortality
• Consequences of coinfection for vaccine efficacy
• Public health and integrated control programs for coinfections
• Influence of coinfections on gut function, diet, and noncommunicable diseases (in particular metabolic syndromes and malnutrition)
• Coinfections during pregnancy and child growth and development