Source: Chapter 7, Contagious Divides (Nayan Shah) | Section: "Detecting 'Parasites'"
Tags: hookworm, filariasis, clonorchiasis, liver fluke, bacteriology, Angel Island, parasite detection, Dr. M. W. Glover, Asian Indian immigration, healthy carrier, tropical medicine, medical exclusion
After 1910, bacteriological testing of blood and feces replaced visual inspection as the primary tool of medical exclusion at Angel Island. Hookworm diagnosis became a powerful weapon against Asian Indian and Chinese immigration, even though the disease was treatable and often showed no visible symptoms. The concept of the "healthy carrier" allowed the PHS to declare apparently well immigrants to be dangerous, and the bacteriological lab gave medical authority a new, seemingly incontestable basis for racial exclusion.
Hookworm
An intestinal parasite causing anemia, fatigue, and diminished physical and mental development. Often called the "germ of laziness." Not considered fatal, but the parasite could remain in the host for ten years. Treated with thymol, which flushed the worms from the intestinal wall.
Filariasis (threadworm)
A parasitic infection detected through blood testing. The filaria organisms circulated in the blood only at night, requiring the controversial "midnight examinations" where blood was drawn from detainees' ears at midnight.
Clonorchiasis (liver fluke)
A parasitic infection linked by the PHS to the Chinese and Japanese diet of raw fish. Caused enlarged livers, bloody diarrhoea, and jaundice. Added as an excludable disease in 1917. Reclassified in 1927 after five years of PHS study confirmed it could not spread in North America.
Healthy carrier
A person who harboured parasites but displayed no visible symptoms of illness. This concept was central to the PHS's expansion of bacteriological testing: apparently healthy immigrants could be declared dangerous through microscopic examination alone.
Dr. M. W. Glover
PHS inspector at Angel Island who pioneered mandatory bacteriological testing of Asian immigrants. In September 1910, he detected hookworm in Asian Indian detainees and expanded testing to all Asian Indian and Chinese passengers. He openly boasted that hookworm testing was "a large factor in stopping the influx of East Indians into this country."
Asiatic Exclusion League
A white labour organisation on the Pacific Coast. After news of hookworm detection broke in 1910, the League endorsed mandatory bacteriological examination of all Asian immigrants and argued that all "Orientals" should face the same strict barriers as Chinese arrivals.
"Germ of laziness"
A common nickname for hookworm, reflecting the way the disease's symptoms (lethargy, diminished productivity) were used to characterise its sufferers as unfit for labour and likely to become public charges.
Before 1910, PHS officers relied on physical observation to assess immigrant health
The establishment of a full-scale bacteriological laboratory at Angel Island in 1910 changed everything
Microscopic slides and germ cultures allowed officers to "see" beneath the skin
Blood and feces samples revealed parasites invisible to the naked eye
Bacteriology provided seemingly incontestable scientific evidence for exclusion
The origin story is specific and telling:
In September 1910, Dr. Glover detained six Asian Indian men at the Angel Island Hospital with an initial diagnosis of anaemia
After testing their feces, he identified hookworm ova under the microscope
He then tested all Asian Indian patients in the hospital and found hookworm in over 70% of them
Glover extended mandatory testing to all Asian Indian and Chinese passengers
The investigations merged these groups into the category of "Asian" and confirmed the suspicion that all Asian immigrants might harbour parasites, even when apparently healthy
Glover's ambitions went further:
He championed Angel Island as a laboratory for tropical disease research, citing the "excellent opportunity for study of intestinal parasites as the supply of material is large and constantly new"
He used hospital patients as laboratory specimens without consent, in one case administering drugs to extract "a hundred or more of the worms themselves" from an Asian Indian patient
He boasted in his annual report that hookworm testing was "a large factor in stopping the influx of East Indians" into the country
Hookworm testing did not emerge in a vacuum. It was spurred by an internal crisis:
In May 1910, an Immigration Service officer accused the Angel Island commissioner Hart H. North of corruption and negligence in medical exclusion
The complaint: many Asian Indian migrants with "poor physique" were being admitted despite being likely to become public charges
Glover testified that Immigration Service officers were not qualified to judge "physical capability" without a full medical exam
Bacteriological tests gave the PHS a tool to assert authority over the Immigration Service
The external political context amplified this:
Nearly 7,000 Punjabi men had immigrated during the peak years of 1907–1911
White labour organisations and sympathetic newspapers campaigned against Asian Indian immigration
The San Francisco Bulletin hailed Glover's discovery as "an effective dam to the torrent of Hindu immigration"
The Asiatic Exclusion League endorsed mandatory bacteriological exams for all Asian immigrants
Hookworm, threadworm, and roundworm could exist in a host with no visible symptoms
These "healthy carriers" appeared well but supposedly harboured dangerous portable pathogens
Glover feared these pathogens would have "devastating effects on unsuspecting white Americans"
The concept meant that physical observation was no longer sufficient; only microscopic examination could reveal the truth
This gave the PHS unprecedented power: any apparently healthy immigrant could be declared medically excludable
The filaria parasite circulated in the blood only at midnight, requiring blood draws at that hour
The San Francisco Chronicle reported on a midnight scene at Angel Island where Dr. Glover cut a Chinese boy's ear "until the blood dripped, while they gazed in rapt attention at the ruddy gore"
The Chinese Defender ridiculed these "midnight examinations" and the "shedding of blood" as evidence of intimidation and terror
Chinese journalists, the Chinese consul, and attorneys all protested that the terror of the physical encounter could not be justified by laboratory results
Many physicians also doubted diagnoses furnished through the new bacteriological methods
In 1917, liver fluke was added as an excludable disease
The PHS linked it to the Chinese and Japanese diet of raw fish, using this cultural specificity to justify race-specific testing
In 1921, Chinese merchants Pang Hing and Hee Fuk Yuen filed federal lawsuits challenging the practice as "unequal administration of the law"
Their lawyer argued that "Caucasian passengers no matter what class or nationality are exempt from the microscopic test of their feces, only the Oriental alien" was required to submit specimens
The federal courts upheld the practice, ruling that cultural susceptibility could justify special investigation and that not testing white and Asian first-class passengers was not discriminatory
Mrs. Chin, detained for two weeks in 1913, described the treatment:
She took thymol medicine three times daily and was not allowed to eat
"Your body started feeling as weak as a snake's. You would walk to the hillside and lay down like a drunkard."
After the medicine worked, she was given a pan for another feces examination
"Even if you didn't have anything to go, you forced it out. After they examined it, overnight, they would give you a little something to eat. Then you had to be examined again. If you were cleared, you could go."
Charles T. Nesbitt, health director of Wilmington, North Carolina, testified before the U.S. House of Representatives that:
Asia was the "fountain" of the "most destructive pestilence" in history
Asians had "acquired such a high state of immunity" that they had become "unconscious carriers"
Asian immigrants were likely to "introduce among whites on the Pacific Slope insidious chronic diseases which will subject them to physical deterioration"
Immunity produced stronger, more dangerous bodies that could destroy the health of a "parasite-free" white race
The judgment collapsed two things together: having a parasite organism within the body, and being a social parasite (dependent, unproductive). The language of parasitology mapped directly onto anti-Asian immigration rhetoric.
⚠️ The "healthy carrier" concept is pivotal. It allowed the PHS to exclude apparently well immigrants by claiming only microscopic science could reveal the truth of their bodies.
⚠️ Glover's role is a case study in how individual actors used scientific authority for political ends, openly boasting about stopping Asian Indian immigration.
⚠️ The Pang Hing case (1921) is a key legal challenge. The courts upheld race-specific testing by ruling that cultural susceptibility (diet of raw fish) justified targeted investigation.
⚠️ The conflation of biological parasites with "social parasites" shows how medical and political language reinforced each other.
⚠️ The use of detainees as experimental subjects without consent is an early example of medical ethics violations in immigration enforcement.
Q: How did Dr. Glover's discovery of hookworm in Asian Indian detainees in 1910 change medical exclusion practices at Angel Island?
A: Glover extended mandatory feces testing from six initially detained Asian Indian men to all Asian Indian and then all Chinese passengers. The bacteriological lab replaced physical observation as the primary diagnostic tool, the concept of the "healthy carrier" meant apparently well immigrants could be excluded, and hookworm replaced trachoma as the leading cause of medical deportation.
Q: Why did the courts uphold race-specific parasite testing in the Pang Hing case?
A: The courts ruled that cultural susceptibility (the Chinese and Japanese diet of raw fish, which was linked to liver fluke) could be a valid criterion for special investigation. They concluded that narrowing testing to "second-class Oriental passengers only" was not discriminatory, and that the surgeon general's authority to classify diseases was not subject to judicial review.
Q: What was the political significance of the "healthy carrier" concept for immigration exclusion?
A: It meant that physical appearance of health was no longer sufficient grounds for admission. Any apparently healthy immigrant could harbour invisible parasites detectable only through bacteriological testing, giving the PHS power to exclude immigrants with no visible symptoms. Since the PHS only had the resources and political will to test Asian passengers, the concept functionally targeted racial groups while being framed as universal science.
Q: How did the conflation of biological and social "parasites" function in anti-Asian immigration rhetoric?
A: Figures like Charles Nesbitt collapsed the identification of a parasite organism within the body with the status of being a social parasite (dependent, unproductive). Asian immigrants were characterised as "unconscious carriers" whose immunity made them more dangerous, capable of introducing "insidious chronic diseases" that would destroy white productivity. The medical vocabulary of parasitology mapped directly onto the political language of exclusion.
hookworm, filariasis, threadworm, clonorchiasis, liver fluke, bacteriology, microscopic examination, healthy carrier, Dr. M. W. Glover, Angel Island lab, tropical medicine, Asian Indian immigration, Punjabi immigrants, Asiatic Exclusion League, "germ of laziness," midnight examinations, Pang Hing case, medical experimentation, parasite, social parasite, public charge, immigration exclusion, feces examination, blood testing, thymol treatment, Chinese Defender, San Francisco Chronicle