CEE 454 Team EHS: Drew Lebowitz, Stephen Song, Jacob Krall, & Daniel Smith

CEE 454 Team EHS: Drew Lebowitz, Stephen Song, Jacob Krall, & Daniel Smith

DRAFT #2

September 28, 2004

History of Public Health: Roles of Water Treatment and Public Health Interventions

Abstract:

The rates of changes in typhoid mortality rates for ten years prior to and ten years following water treatment interventions were analyzed to determine the impact of the interventions on public health in seventeen US cities from 1881-1937. The analysis shows that no one treatment scheme, chlorination, filtration, or both simultaneously, can be credited with unilaterally lowering the typhoid mortality rate. The significant increases in the decline in typhoid mortality correspond more closely with the year of the intervention, with the earliest years of treatment introduction, 1903 and 1908, seeing the steepest drop offs. However, the dramatic increases in the decline of typhoid mortality with the introduction of chlorination or filtration in select cities cannot be ignored when evaluating their effects on disease reduction. In addition to the water treatment interventions, the role of mass marketing of personal hygiene in the time period was found to have increased social awareness of the connection between hygiene and health. The capitalization of a new market for health products created through advertising benefited public health. Contemporary foreign health interventions stressing hand-washing are presented to provide a modern corollary to the advents in hygiene that developed in turn-of-the-century America. Evidence of the reduction in diarrheal diseases carried by the same exposure routes as typhoid point to a certain conclusion that the adoption of a culture of personal hygiene during late nineteenth and early twentieth century America reduced the rate of typhoid contraction, and therefore typhoid mortality.

Introduction:

At the end of the nineteenth century the large metropolitan centers of the United States suffered the public health consequences of intense population density and industrialization without the infrastructure to maintain the standard of living urban Americans expected at the close of the twentieth century. Increased demand for piped water stimulated the construction of water supply systems which often relied upon asource unprotected from contamination. Little heed was initially paid to water quality, leading to the efficient spread of water borne disease, including typhoid fever (Schoenen 3875). Indeed, mortality rates for adults and infants were much higher in the late nineteenth century, the so-called “urban penalty”, mostly due to infectious disease (Grant, Miller and David M. Cutler 9).

By the 1910’s and 1920’s, water treatment works employing filtration, chlorination, or both unit processes became essential components of municipal infrastructure systems to provide safe, drinkable water. The same period witnessed a drastic decline in the urban typhoid mortality rate. Christman contends that the use of filtration and chlorine for the disinfection of drinking water was one of the most significant public health advances of the millennium (1). Shoenen states that while disinfection of water with chlorine contributed to typhoid reduction pathogens cannot be sufficiently eliminated with only a chemical disinfectant (3874). This paper will analyze the typhoid fever mortality rate in seventeen cities in the United Statesduring the period from 1881 to 1937 to investigate how the introduction of chlorination and filtration affected typhoid reduction. Hygienic principles and how they tied into American culture of the era are explored as additional explanations for typhoid’s demise.

Typhoid Background Information

Salmonella typhi and Samonella paratyphi are the two species of bacteria that cause the disease called typhoid fever. The illness is characterized by generalized systemic fever, anorexia, malaise, constipation, and ulcers and hemorrhages in the intestines. Common enterocolitis can result with fever causing symptoms such as nausea, diarrhea, vomiting, and dehydration. Salmonella typhi has a fatality rate of 16%, but is reduced to 1% with antibiotic therapy; the paratyphi species is less severe. Typhoid can be contracted by the ingestion of 100,000 Salmonella typhi or >1,000 Salmonella paratyphi. Humans are the only hosts for the typhoid bacteria (Salmonella typhi Material Safety Data Sheet 1). It is a feco-orally transmitted pathogen –transmission only occurs by direct or indirect contact with human waste. Common exposure routes include ingestion of waterfecally contaminated from sewage or hands, food contaminated by dirty hands, or person-to-person contact. Typhoid can survive outside humans on surfaces and foods for extended periods of time, especially milk products (Salmonella typhi Material Safety Data Sheet 2). The bacterial presence in water can be mitigated by filtration, boiling, radiation exposure, and chlorination with intensive mixing. However, effective disinfection using chlorine in laboratory tests requires intensive mixing and individually suspended organisms – conditions that rarely exist in practice. Particulate matter in water protects the pathogen from the action of chlorine (Shoenen 3883). Hand-washing using regular soap is an effective means to decontaminate the part of the body primarily responsible for transmitting the disease to water, food, or into the mouth.

Results & Discussion

At first glance, the data for typhoid mortality rate in the United States between the years of 1881 and 1937 appears to offer clear evidence that chlorination and filtration of municipal drinking water should be credited with the virtual elimination of typhoid from the country. In Milwaukee, the introduction of chlorination reverses what was an upward trend in the typhoid mortality rate and produces an immediate and drastic decline in typhoid deaths. In Cincinnati, the typhoid mortality rate was hovering above 30 per 100,000 in the late nineteenth century. Within five years after filtration of the water supply began that number had dropped to7 per 100,000. Baltimore experienced a similarly steep decline in typhoid mortalitywithin a few years of simultaneously introducing chlorination and filtration. However, a more careful look at the data for the seventeenUS cities tells a more complex story. Of the cities studied, eight introduced chlorination without filtration in the period between 1881 and 1937, four introduced filtration before chlorination during those years and 4 introduced both technologies within five years of each other. One city, Boston, did not introduce either technology during the period of interest.

To determine if chlorination and filtration can be correlated with the decline in city-wide typhoid deaths, the average rates of change of the typhoid mortality per 100,000 in the ten years before and the ten years after the introduction of chlorination, filtration, or both interventions together were compared (see Fig. 1). The rates of change of the typhoid mortality rates were compared instead of the absolute changes in mortality rates to isolate the effects of the water treatment interventions on the reduction of the disease. The units for the pre and post-intervention slope columns in Table 1 are typhoid deaths per 100,000 per year. The % change was calculated as (pre-intervention 10 year slope – post-intervention 10 year slope)/abs(pre-intervention 10 year slope) *100%. Thus, a positive value corresponds to a steeper decline in typhoid mortality after the intervention.

The average percent change of the rate of change in typhoid mortality after introduction of chlorination alone was 4%, the average percent change after introduction of filtration alone was 121%, and the average percent change after introduction of both technologies together was -25%. These calculations suggest that only filtration alone produced a significant affect on typhoid mortality rate while chlorination alone produced a very small affect and the introduction of both technologies together tended to decrease the rate of decline in typhoid mortality.

Table1 - Rate of change of the typhoid mortality rate before and after introduction of treatment technologies by city and year.

These generalized statistics, however, tend to be misleading. The % change in slope correlates more precisely with the timing of the introduction of the treatment technologies than with their ability to make the decline in typhoid mortality steeper. The table shows that cities which introduced one of the technologies in 1903 or 1908 always experienced a substantial increase in the rate of decline in typhoid mortality. The rate of decline actually decreased after the introduction of treatment in nine out of eleven cities where the treatment began in 1913 or after. Comparing the rate of change in mortality with the intervention timing reveals that between the years of 1903-1913, and 1908-1913 in particular,most of these American cities experienced a steep decline in typhoid mortality regardless of theintroduction of water treatment. Between the years of 1913-1937 typhoid mortality rates continued to decrease, but the data suggests that the typhoid mortality rate decline had become more moderate independent of the introduction of a new treatment technology.

The data does not provide ample evidence that chlorination and filtration of the water supply were responsible for the elimination of typhoid mortality in the United States in the late nineteenth and early twentieth centuries. Only two of eight cities which introduced chlorination experienced positive percent change in the rate of change of the typhoid mortality rate (see Table 1). Although the all cities which implemented filtration alone saw an acceleration in the drop in typhoid mortality, only one of the cities which introduced filtration and chlorination simultaneously experienced a positive percent change. However, this does not mean that these technologies did not play an integral part in the solution. The sudden drops in typhoid mortality rate in Milwaukee, Cincinnati, and Philadelphia that correspond perfectly with the introduction of water supply treatment suggest that treatment did make a difference in these cities even though the conclusion cannot be generalized for the country as a whole. It is critical to remember that there are multiple exposure routes for typhoid. The public health related conditions that varied from city to city such as the safety of the water source, prevalence of hand washing in the population, and sewerage on top of which chlorination and filtration were implemented undoubtedly played a role in whether water treatment produced a decline in typhoid mortality rate. The inconclusiveness of the analysisdoes not show that filtration or chlorination do not help remove typhoid from drinking water, but it challenges the idea that the introduction of chlorination and filtration to municipal water supply systems unilaterally eliminated typhoid fever. Other factors were clearly at work in American cities during this erato produce the drastic improvement in public health.

Public Health Awareness Through Marketing

Cultural factors must be considered to help explain why typhoid mortality rates sharply declined in the United States at the beginning of the twentieth century. This era saw a tremendous improvement in the population’s awareness of hygiene and personal hygiene practice. In order to understand this phenomenon, it is necessary to realize that it was not until the very end of the nineteenth century that the germ theory of disease was developed. With the germ theory of disease, it was finally feasible to begin the process of scientifically determining the causes of diseases. This became the impetus for improving personal hygiene.

Because typhoid is transferred directly from person to person, it is obvious how improved hygiene can reduce the likelihood of transmission. In her book, Stronger than Dirt, Julianne Sivulka contends that mass marketing tried to exploit the public’s fear of germs. While the germ theory of disease was still new to many people, it “provided marketers with another argument to work into their sales pitches” (Sivulka, 110). Sanitary reformers and advertisers used this new knowledge to try not only to clean up cities and raise awareness for personal hygiene, but also to make a profit by convincing the public that they were in need of products such as soap. Therefore, “the proliferation of soap products and the discourse about hygiene definitely recast nineteenth-century attitudes toward personal cleanliness” (Sivulka, 110).

Social awareness of hygiene was further enhanced through the design of the modern bathroom. The modern bathroom made it fashionable to be hygienic. Tile and ceramic were the materials of choice because they were non-porous and did not contain cracks or crevices that could lodge dirt. Although they were still considered to be expensive materials for this time period, the large demand to modernize bathrooms made these materials widely available. These materials were deliberately made white even though they could be tinted other colors. From a psychological viewpoint, this made sense because white tends to imply cleanliness, and marketers were trying to sell the idea that the modern bathroom was clean (Sivulka, 118). Advertising bathroom products was conducted through a variety of printed media, and the goal was to increase the appreciation and importance of bathroom interiors (Sivulka 117). Due to the success of advertisers in convincing the public that their bathrooms were in need of modernization, bathtubs evolved from portable fixtures to built-in devices. This is one example that shows how the modern bathroom was created.

While advertisers of bathroom products and fixtures may have originally been trying to make money off of their products, they ended up doing something that would have a much larger social impact. By modernizing the bathroom, they increased public awareness of personal hygiene. Soap and towel companies urged consumers to bathe often in order to increase the demand for their products. However, this paved the way for improved hygienic habits. While chlorination and filtration were developed throughout this time period to improve the quality of municipal drinking water, increases in personal hygiene also contributed to the decrease in typhoid cases. The culture of the early twentieth century stressed the importance of hygiene by modernizing the bathroom. This was achieved through a relentless campaign of advertising that tried to capitalize on the newly discovered germ theory of disease, and by convincing people that their cleanliness was of the utmost importance. What originally began as a business tactic eventually became the impetus for improving personal hygiene, and therefore public health, in early twentieth century America.

Case Studies in Hygiene Education

Hand-washing, face-washing, and other educational measures seem to be intuitive methods of reducing morbidity from diarrheal and other diseases. However, quantitative support for the effects of hygienic factors is found by examining modern case studies. Here, two studies are examined which chronicle the effects of hygiene on diarrheal diseases. While the studies come from outside of the U.S., they are useful in clarifying the effect of specific public interventions that occurred in this country. The vast hygienic and technological changes that took place in the U.S. in the late nineteenth and early twentieth centuries make it very difficult to identify the true cause of reductions in disease. Looking at some areas outside the U.S. lets us isolate these factors, as they mimic the situations of development in this country. The studies differ from U.S. urban treatment in that they are smaller-scale applications of similar technologies. However, in terms of analyzing the relative effects of differing intervention techniques, the data are a very useful tool.

The research of Esrey, et al (1991) indicates that a combination of hand-washing and other hygienic education can work to cut diarrheal morbidity rates as much or more than chlorine and filtration. The review of 84 diarrhreal morbidity studies found that safe water was better achieved through improvements in “personal and domestic hygiene rather than … drinking-water quality.” The median reduction in diarrheal morbidity based on hygiene intervention was 33%, greater than sanitation, quality, and quantity of water, the other factors which were examined. The rural studies that these data cite are significant because the situation is a model of the American water problem in the early 1900s: water supply contact with fecal matter. Despite unchanged water quality, hygiene and education measures provided the highest reduction in diarrheal mortality.

In Pakistan, Luby et al. (2004) present a comprehensive case study of a controlled trial in to examine the effect of hand-washing on childhood diarrhea outside Karachi, Pakistan. This study was an even more accurate model of the historical American case the study was done in a large urban center, household toilets were present but with discharge flowing into open sewers, and drinking water was highly contaminated with fecal matter. 1050 households were studied with one third of the houses selected as a control group. Plain and antibacterial soap was provided to the non-control houses randomly but to equal numbers. The study reported a reduction of 50% lower prevalence of diarrhea for anti-bacterial soap houses, and a 53% reduction in houses with plain soap. This drastic reduction suggests that even the most basic element of hygienic education, hand-washing, can be a powerful tool in reducing disease transmission among urban communities with fecal-contaminated water. Several elements of the study are inconsistent with the early twentieth century American city: refrigeration was present in nearly half the households, only childhood diarrhea was studied, and the study looked only at incidences of diarrhea rather than mortality from diseases such as typhoid.