Hookworm Persists as US Public Health Problem

By Jerri-Lynn Scofield, who has worked as a securities lawyer and a derivatives trader. She now spends much of her time in Asia and is currently working on a book about textile artisans.

Hookworm, a disease of extreme poverty thought largely to have been eradicated in the United States, persists as a public health problem in some populations, according to a peer-reviewed paper, Human Intestinal Parasite Burden and Poor Sanitation in Rural Alabama, published yesterday in the American Journal of Tropical Medicine and Hygiene.

The disease affects 430 million people worldwide, largely in Africa and Asia, causing iron deficiency, impaired cognitive development, and stunting in children, and is considered a neglected tropical disease (NTD).

As reported by The Guardian in Hookworm, a disease of extreme poverty, is thriving in the US south. Why? :

The study, the first of its kind in modern times, was carried out by the National School of Tropical Medicine at Baylor College of Medicine in conjunction with Alabama Center for Rural Enterprise (ACRE), a nonprofit group seeking to address the root causes of poverty. In a survey of people living in Lowndes County, an area with a long history of racial discrimination and inequality, it found that 34% tested positive for genetic traces of Necator americanus.

As recently as the 1930s, the southern United States had a high prevalence of hookworm infections, which affected intellectual performance and caused lethargy, according to How a Worm Gave the South a Bad Name. Initial surveys of populations at that time found that as much as three-quarters of the populations of certain areas were infected.

“Hookworm is a 19th century disease that should by now have been addressed, yet we are still struggling with it in the United States in the 21st century,” said Catherine Flowers, ACRE’s founder, as quoted in The Guardian.

New Deal Eradication Efforts

During the New Deal, the federal government launched a public health initiative to control hookworm infections:

To control the disease, thousands of individuals were treated, decreasing prevalence to 39%. After these interventions, there were increases in school enrolment, attendance, and literacy, and those within the treated cohort had substantial gains in long-term incomes. However, because of posttreatment reinfection and widespread transmission, hookworm infection and disease continued to persist in the southern United States, especially in areas of extreme poverty. According to a study in the 1950s, rural Alabama still suffered from a high prevalence of hookworm infection in schoolchildren, with some counties having 60% infection. With improved sanitation and waste disposal infrastructure, in association with aggressive economic development in the southern United States, the prevalence of hookworm infection decreased (paper, p. 2, citations omitted).

The conditions that cause hookworm infections have not vanished, yet contemporary researchers have largely failed to investigate how prevalent they may remain:

In the 1990s, surveillance studies for enteropathogens in southern Alabama show a 30% prevalence for all soil-transmitted helminths combined, including Ascaris lumbricoides, N. americanus, and Enterobius vermicularis. This part of the United States was identified as one at high risk for intestinal helminth infections. A more recent systematic review, however, found that few surveys for intestinal helminth infections have been conducted in recent decades, with limited information about these diseases, especially in poor rural and southern United States (paper, p. 2, citations omitted).

Poor Sanitation and Hookworm

While hookworm is by no means as widespread in the south now as in the past, the regulatory breakdown that allows hookworm to persist as a public health problem in places such as Lowndes County predates Trump, as discussed further in this February post, EPA Failures Predate Trump: Evidence Emerges of Tropical Parasites in Rural America.

According to The Guardian:

The challenge to places like Lowndes County is not to restore existing public infrastructure, as Trump has promised, because there is no public infrastructure here to begin with. Flowers estimates that 80 per cent of the county is uncovered by any municipal sewer system, and in its absence people are expected, and in some cases legally forced, to provide their own.

Exposure to untreated raw sewage is the major culprit in hookworm infections. Researchers chose to study Lowndes County because of its previous high hookworm burdens, degree of poverty, and use of open-sewage systems:

The “Black-Belt” soil native to this area is composed of a firm sedimentary limestone bed overlain with a layer of dark, rich soils, which requires expensive septic systems for proper waste disposal. In Lowndes County, Alabama, where the per capita income is $18,046, and 31.4% of the population lives below the poverty line, sanitation systems are unaffordable. For rural, impoverished individuals, the main form of waste removal involves use of “straight piping,” a method involving a series of ditches or crudely constructed piping systems to guide human waste away from the residence. Most pipes never reach more than 10 meters in length, and during rainstorms or flooding, the residents report visible stool entering their homes (reported by ACRE, unpublished data). (paper, p.2, citations omitted).

How Widespread is Hookworm in the United States?

The paper did point out methodological shortcomings, particularly the small size of the sample studied. Sixty-six people participated in the study, and 55 provided stool samples.

Unfortunately, because of the mistrust stemming from the illegalities of the self-constructed “straight pipe” waste disposal systems, as well as toward the medical community, the number of individuals included in this study was much smaller than expected. By working with the ACRE organization, which has fostered trust and worked with several members within the community, the research team was able to include more participants, but some of the data obtained from the questionnaires were incomplete because of different individuals performing the interviews. This should be considered when interpreting the results of this study. Performing subgroup analyses with the information provided some baseline data that could be assessed and compared among those being tested for infection. These incomplete forms were still included in data analyses given the difficulty of obtaining this information by other means and to provide further insight into the local population (paper, p. 7).

It’s difficult to speculate, based on this study alone, how widespread hookworm is in the United States. While the sample size is indeed low, “the results are so stark”– with 34% testing positive for hookworm– “that the Houston scientists now want to conduct a larger survey across the region”, according to The Guardian.

“We now need to find how widespread hookworm is across the US,” said Dr Peter Hotez, dean of the National School of Tropical Medicine, who along with Rojelio Mejia led the research team. Hotez, who has estimated that as many as 12 million Americans could be suffering from neglected tropical diseases in poor parts of the south and midwest, told the Guardian the results were a wake-up call for the nation.

“This is the inconvenient truth that nobody in America wants to talk about,” he said. “These people live in the southern United States, and nobody seems to care; they are poor, and nobody seems to care; and more often than not they are people of color, and nobody seems to care.”

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