Emerging and Reemerging Neglected Tropical Diseases: Review of Key Characteristics and Risk Factors

Background:  In global health, critical challenges have arisen from infectious diseases. This includes emergence and re-emergence accelerated by rapid human development, including numerous changes in demographics, populations and the environment. Within this context, neglected tropical diseases have historically lacked adequate attention leading to insufficient prevention and treatment options. Yet NTDs that are also categorized as emerging or re-emerging infectious diseases (“EReNTDs”) may represent an even more serious threat not adequately examined for unique risk characteristics.

Methods:  We conducted a literature review by searching PubMed/MEDLINE and Google Scholar databases to review the scientific literature for discussion of EReNTD subject areas. We also conducted general Google search engine inquiries using key words associated with EReNTD and supplemented the peer-review literature with information from news reports, press releases, organization websites, and program and intervention descriptions.

Findings:  Five specific EReNTDs that fit both the WHO’s definition of an NTD and the CDC’s classification as an EID/ReID were identified: dengue, Chagas Disease, cysticercosis, human African trypanosomiasis, and rabies. Compared with the broader category of NTDs, EReNTDs present additional risks as they pose a “dual” threat given they are spreading and emerging in previously non-endemic areas and are also “neglected”. Specifically, the spread of EReNTDs is accelerated by ever increasing globalization, travel, trade, as well as environmental factors, climate change, population growth, migration, and urbanization.

Discussion:  The clinical, socio-economic, and environmental factors associated with EReNTDs reveal a sharing of many important characteristics warranting detailed discussion. These common risk factors include: vector-related risk factors; disease-related risks; drug treatment and development challenges; social determinants of health-related risk factors; environmental/climate change risk factors; and disease control-related challenges. Primarily, the diseases within the EReNTD category are largely widespread impacting millions worldwide; disproportionately affect impoverished, resource-poor communities; and recently have spread to other higher income country settings through migration-international trade/travel.