Environmental Policy and Public Health

Emerging Health Hazards and Mitigation, Volume 2

Barry L. Johnson, Maureen Y. Lichtveld

• Editore: CRC Press
• Anno: 2022
• ISBN:
  9781000518351
• Edizione: 3
• Argomento: Ciencias biológicas
• Categoria: Ciencia medioambiental

Written by environmental health experts with long teaching and professional careers in policy and public health, the third edition of Environmental Policy and Public Health comprises two volumes, addressing key physical hazards in the environment that impact public health. The first volume on Principal Health Hazards and Mitigation is complemented by the second volume, Emerging Health Hazards and Mitigation.

Volume 2 discusses emerging health hazards and mitigation including environment-related infectious diseases, COVID-19 pandemic, social justice, and drugs and public health. New in this volume are a chapter on firearms violence as a public health hazard, a chapter on transportation and how built environments can affect human health and social well-being, and a chapter on noise and light pollution. As human populations increase and technology adds more devices to daily use that generate noise and light, adverse human and ecological health effects have become recognizable and require time-sensitive policy actions to mitigate and where possible prevent adverse health effects. Each chapter explains with great clarity how new environmental health issues are translated into public health policies. The volume concludes with case studies and practice questions to facilitate interactive learning for upper-level undergraduate and graduate students taking courses in public health and environmental sciences. The case studies and practice questions allow for a diverse portfolio of in-person and hybrid pedagogical strategies and tools at the fingertips of faculty who not only teach policy courses but whose course topics have policy relevance, such as climate and health.

1 Environment-Related Infectious Diseases

DOI: 10.1201/9781003212621-1

1.1 Introduction

Prior chapters in Volume 1 have addressed chemical hazards in the environment that have led to policymaking to control the effects on human and ecological health. This chapter describes a different kind of environmental-related outcome, infectious diseases. These diseases are caused by organisms or pathogens (such as viruses, bacteria, fungi, parasites, protozoa) that can be transmitted through physical contact with or exposure to bodily fluids of an infected person. These causal agents are collectively called vectors, which are defined as living organisms that can transmit infectious diseases between humans or from animals to humans. A particularly hazardous disease agent is the mosquito. As will be subsequently discussed, mosquitoes are a major environmental vector of human disease. Infectious diseases are constantly circulating within a population. However, when an infectious disease causes an increased, or unexpected, number of cases, it can be classified as an outbreak. Health departments at federal, U.S. state, territorial, and local levels monitor cases of infectious diseases and implement actions to control emerging and re-emerging pathogens within their populations. Described in this chapter are various infectious agents in the environment and policies and public health actions that are purposed to mitigate the adverse human and ecological health effects.

1.2 Infectious Diseases – A Global Perspective

In high-income countries, medical and public health advances and sound environmental policies created a shift toward noncommunicable, chronic conditions. Over the last 10 years, lower and middle-income countries also saw a significant increased mortality and morbidity associated with noncommunicable diseases such as cardiovascular diseases while these countries continue to face threats of endemic infectious diseases. However, unlike developed countries, most of the health infrastructure needed to combat both types of diseases is often underdeveloped and fragile.

Health departments at federal, state, and local levels monitor cases of infectious diseases and implement actions to control emerging and re-emerging pathogens within their populations.

The U.S. recognizes that infectious diseases remain a problem worldwide. The U.S. commitment to combat the spread of infectious diseases is visible through global programs and funds. In the U.S., the Centers for Disease Control and Prevention (CDC) is the leading national public health agency in charge of early detection, control and prevention, and preparedness. CDC’s National Notifiable Diseases Surveillance System (NNDSS) collects, analyzes, and shares health data on notifiable diseases among local, state, territorial, federal, and international public health departments.

Globally, the World Health Organization (WHO) is the UN’s public health agency and the leading international health organization, supported by 193 member states. The WHO has established a disease surveillance network comprised of national and international medical laboratories in its member states. CDC, the UK Public Health Laboratory Service, the French Pasteur Institute, and schools of public health globally report to WHO on a series of infectious diseases [1]. Under WHO’s International Health Regulations (IHR), member states are legally required to report infectious diseases of international importance. The WHO also provides operational support to response efforts during an epidemic and strengthens national core capacities to prevent, prepare, and recover for and from emergencies [2]. Furthermore, WHO’s environmental guidelines and policies on drinking water, sanitation and hygiene, and the use of chemicals such as insecticides directly and indirectly contribute to the prevention of infectious diseases.

1.3 The Environment and Infectious Diseases

The primary determinant of infectious diseases is the pathogen (the infectious agent). A pathogen is any organism, usually a microbe, that can cause disease in a host. The host, the second determinant of infectious disease, is exposed to the pathogen and either harbors the disease, or becomes ill [3]. Public health is concerned mostly with human hosts; however, animal hosts can have an impact on human health. The environment is necessary for the exposure to and the spread of the infectious agent and is therefore the third determinant of infectious disease. As depicted in Figure 1.1, Triangle of Disease, the three vertices of the triangle connect the pathogen, host, and environment to allow the transmission of infectious diseases. This chapter describes the role of the environment in transmission and control of infectious diseases [4].

FIGURE 1.1 Epidemiological triangle of vector-borne disease. (CDC, 2006. Principles of Epidemiology in Public Health Practice, 3rd Edition. Office of the Associate Director for Communication, Centers for Disease Control and Prevention, Atlanta, Georgia. https://www.cdc.gov/about/organization/oadc.html)

The primary determinant of infectious diseases is the pathogen (the infectious agent). A pathogen is any organism, usually a microbe, that can cause disease in a host.

1.3.1 Cholera

Cholera is caused by the bacterium Vibrio cholerae. During the 1800s, cholera outbreaks occurred frequently in the U.S. Cholera is transmitted by ingestion of water or food that has been contaminated with human feces. Upon infection, the cholera bacterium releases a toxin (classified as O1 or O139) that can cause severe diarrhea and dehydration [5,6]. If left untreated, it can be fatal. Currently, cholera is mostly travel-associated [7,8]. The CDC’s Cholera and Other Vibrio Illness Surveillance System was created in 1988 in partnership with the FDA and the Gulf Coast States to obtain information on any Vibrionaceae associated-illness and provide information about risk groups and exposure risk [9]. Other systems that conduct surveillance on Vibrio associated-illness include CDC’s National Notifiable Diseases Surveillance System, the National Antimicrobial Resistance (AMR) Monitoring System, and the National Outbreak Reporting System. All cholera cases also have to be reported to the WHO in compliance with international health regulations.

Cholera is transmitted by ingestion of water or food that has been contaminated with human feces. If left untreated, it can be fatal.

Cholera is endemic in more than 50 countries worldwide. The last endemic cholera outbreak in the U.S. occurred in 1911. Most cases occur in African and Asian countries where populations do not have access to improved drinking water sources. The WHO maintains and publishes weekly reports of aggregate national cholera data. The 1969 WHO IHRs and the 2005 ratification require WHO notification of all cholera cases. Cholera, however, is estimated to be heavily underreported, with official estimates representing 5%–10% of all annual cases. It is estimated that an annual 1–4 million cholera infections occur worldwide, resulting in an estimated 21,000–143,000 annual deaths [10].

Cholera disease is particularly fatal to children. A simple scientific advancement, known as Oral Rehydration Therapy, replaces essential salts and body fluids through a sodium glucose mixture known as Oral Rehydration Salts (ORS). ORS are cheap, globally distributed, and credited for reducing cholera as well as other diarrheal disease mortality, in children by more than 54% from 1.3 million in 2000 to fewer than 600,000 in 2013 [11]. However, even with an inexpensive and effective solution to decrease cholera morbidity, cholera prevention is based entirely on providing clean water supplies for human consumption [12]. Many people in developing countries do not have access to safe drinking water on a daily basis [13] (Volume 1, Chapter 39). Recent epidemics have demonstrated poor infrastructure accelerates the spread of water-borne diseases during a natural disaster [10]. An example of an inadequate public health infrastructure follows.

On January 12, 2010, a 7.0 magnitude earthquake struck Haiti. The country was already the poorest country in the Western hemisphere. The Haitian population depended largely on the agricultural sector, residents lived in poverty in overcrowded slums, and Haitians had limited access to sanitation and clean water. Despite a severely limited public health infrastructure, there had never been a case of cholera reported in Haiti [14]. The earthquake and its aftermath killed an estimated 230,000 people and displaced most of the nation’s population. The international community was quick to respond and large-scale search and rescue missions began within days. On October 17, 2010, the first case of cholera was reported to international agencies [15].

Investigations by WHO found that cholera had been introduced into Haiti by the UN’s Nepalese peacekeepers. The Nepalese UN base was located upstream of the Artibonite River, which supplied most of the country with fresh drinking water. Improper sanitation practices at the base, including open dump pits and leaky latrine pipes, allowed human feces infected with Vibrio cholerae O1, serotype Ogawa, a strain found in cholera cases in Nepal to enter the river. By March 2011, more than 500,000 cholera infections were reported with approximately 5,000 deaths. Since its introduction, several subsequent cholera outbreaks have been reported in Haiti [16].

A total number of suspected cholera cases in Yemen in 2017 had risen to 500,000, and nearly 2,000 people had died.

Demonstrating that cholera epidemics do not respect geography or history, a major cholera outbreak occurred in Yemen in 2017. The WHO reports a total number of suspected cholera cases in Yemen in 2017 had risen to 500,000, and nearly 2,000 people had died since the outbreak began to spread rapidly at the end of April 2017 [17]. Yemen’s cholera epidemic was the largest in the world in 2017. The epidemic spread rapidly due to deteriorating hygiene and sanitation conditions and disruptions to the water supply across the country. Millions of people were cut off from clean water, and waste collection had ceased in major cities as a consequence of civil war in Yemen. Later, a restored water treatment plant dramatically reduced a local cholera epidemic. Al Barzakh is one of around 10 water treatment centers in Yemen, and it serves four different districts in Aden, in southern Yemen, as well as the Lahij and the Abyan governorates. As a contribution to public health, UNICEF undertook the plant’s restoration, while also analyzing the infrastructure needs of the region. The plant became fully operational in September 2017, and by January 2018, cholera reports had decreased to 164 cholera cases and zero deaths, which was a 92% decrease in new cholera cases [18].

1.3.2 Typhus

Mites, lice, and fleas are as ubiquitous as ticks. Mites can live freely in the environment or as parasites feeding on mammalian blood and keratin (nails and hair). Due to their parasitic nature, mites can cause common diseases such as scabies (Sarcoptes scabiei) or transmit bacterial diseases such as scrub typhus [19]. Scrub typhus bacteria (Orientia tsutsugamushi) is transmitted by mites throughout Asia and Australia. This wide ecological distribution is due to the geographic spread of the vector and a high population density. Scrub typhus presents as a febrile illness with heada...