In response to Hurricane Mitch, which struck Central America in October–November 1998, the American Red Cross (ARC) and the Centers for Disease Control and Prevention (CDC) collaborated on a 3-year evaluation of the public health impact of ARC's water, sanitation and hygiene education activities in eight study areas in Honduras, Nicaragua, El Salvador and Guatemala. The evaluation compared: 1) access to and use of water and sanitation facilities, 2) the use of hygienic behaviours, and 3) diarrhoeal prevalence in children younger than 3 years of age before (February 2000) and after (February 2002) the interventions had been implemented. The evaluation included household and key informant interviews designed to measure these three components. Water quality of community water sources and household water was evaluated by measuring levels of indicator bacteria. During the final survey, an infrastructure evaluation provided a review of the design, construction, and current operation and maintenance of the water systems and latrines. The integrated water and sanitation infrastructure interventions and hygiene education programmes implemented following Hurricane Mitch effectively decreased diarrhoea prevalence in the target communities.

Irrigation water quality can affect food safety and health and has been identified as a possible source of pathogens in produce linked to disease outbreaks. Many irrigation water sources are subject to contamination from various sources in surrounding watersheds. A systems-based, watershed scale analysis is therefore necessary to comprehensively identify both sources of contamination and the conditions in the environment that facilitated or created that contamination, termed here ‘environmental antecedents’. Three nationwide disease outbreaks linked to produce in the United States (US) are used to illustrate this concept of a watershed scale assessment to investigate potential impacts of irrigation water quality on food safety.

Fourteen years of civil war left Liberia with crumbling infrastructure and one of the weakest health systems in the world. The 2014–2015 Ebola virus disease (EVD) outbreak exposed the vulnerabilities of the Liberian health system. Findings from the EVD outbreak highlighted the lack of infection prevention and control (IPC) practices, exacerbated by a lack of essential services such as water, sanitation, and hygiene (WASH) in healthcare facilities. The objective of this intervention was to improve IPC practice through comprehensive WASH renovations conducted at two hospitals in Liberia, prioritized by the Ministry of Health (MOH). The completion of renovations was tracked along with the impact of improvements on hand hygiene (HH) practice audits of healthcare workers pre- and post-intervention. An occurrence of overall HH practice was defined as the healthcare worker practicing compliant HH before and after the care for a single patient encounter. Liberia Government Hospital Bomi (LGH Bomi) and St. Timothy Government Hospital (St. Timothy) achieved World Health Organization (WHO) minimum global standards for environmental health in healthcare facilities as well as Liberian national standards. Healthcare worker (HCW) overall hand hygiene compliance improved from 36% (2016) to 89% (2018) at LGH Bomi hospital and from 86% (2016) to 88% (2018) at St. Timothy hospital. Improved WASH services and IPC practices in resource-limited healthcare settings are possible if significant holistic WASH infrastructure investments are made in these settings.

Public health has always been, and remains, an interdisciplinary field, and engineering was closely aligned with public health for many years. Indeed, the branch of engineering that has been known at various times as sanitary engineering, public health engineering, or environmental engineering was integral to the emergence of public health as a distinct discipline. However, in the United States (U.S.) during the 20th century, the academic preparation and practice of this branch of engineering became largely separated from public health. Various factors contributed to this separation, including an evolution in leadership roles within public health; increasing specialization within public health; and the emerging environmental movement, which led to the creation of the U.S. Environmental Protection Agency (EPA), with its emphasis on the natural environment. In this paper, we consider these factors in turn. We also present a case study example of public health engineering in current practice in the U.S. that has had large-scale positive health impacts through improving water and sanitation services in Native American and Alaska Native communities. We also consider briefly how to educate engineers to work in public health in the modern world, and the benefits and challenges associated with that process. We close by discussing the global implications of public health engineering and the need to re-integrate engineering into public health practice and strengthen the connection between the two fields.