Bubonic Plague in Los Angeles: The 1924 Outbreak, Response, and Legacy

Bubonic plague arrived in Los Angeles in the fall of 1924, when a pneumonic form of the disease tore through a Mexican immigrant neighborhood near downtown and killed more than 30 people before the city contained it through quarantine, mass demolition, and a rodent eradication campaign. It was the last major urban plague outbreak in the United States. The bacterium that causes plague still lives quietly in wild rodents in the county’s mountains and forests, but it has not caused an urban case in Los Angeles in roughly a century.

How the 1924 Outbreak Began

The first deaths occurred in late September 1924 in the Macy Street District, a crowded neighborhood near downtown also known as “Sonoratown.” A boardinghouse resident named Jesus Lajun found a dead rat. Shortly after, his fifteen-year-old relative Francesca Lajun fell ill and died, with the coroner attributing her death to double pneumonia.¹

A neighbor, Lucena Samarano, who had nursed Francesca, suffered a miscarriage and died. Her husband Guadalupe died days after her funeral. Within six weeks, seven of the eight members of the Samarano family were dead; the sole survivor was fourteen-month-old Raul.¹ Others who attended Lucena’s funeral sickened and died, including Father M. Brualla, who had administered last rites, and an ambulance driver who had transported patients.²

For nearly a month, doctors misread the illness as meningitis, influenza, pneumonia, or typhus. City Health Officer Giles Porter visited a patient’s home on October 3 but failed to recognize the disease.³ On October 30, 1924, Los Angeles County Hospital pathologist Dr. George Maner confirmed the plague bacterium under a microscope.¹ What they were seeing was pneumonic plague, the deadliest and most contagious form, which spreads through respiratory droplets rather than only through flea bites.

The outbreak eventually killed more than 30 people, with some accounts placing the toll as high as 40.²⁴ About 90% of the victims were Mexican.⁵ It was the first human plague in Southern California.

Quarantine and the Racial Shape of the Response

Once Maner confirmed the diagnosis, Acting Health Commissioner Dr. Elmer R. Pascoe ordered a strict quarantine of the affected neighborhood, enforced by 60 police officers who prevented residents from entering or leaving.² In the Belvedere Gardens neighborhood of East Los Angeles, county health chief J.L. Pomeroy timed the quarantine for the middle of the night, later admitting officials feared the Mexican residents “would scatter” and wanted to avoid “a general stampede.”³ Approximately 2,500 Mexican Americans were quarantined.⁴

Civic boosters, the Chamber of Commerce, and the local press worked at the same time to suppress news of the outbreak to protect tourism and harbor business. The Los Angeles Times avoided the word “plague” for nearly a week after the quarantine began, calling the illness a “Strange Pneumonia.” When the paper did cover the story, it identified the affected area as the “Mexican Quarter” and listed victims by Spanish surname. Methodist radio host Reverend Robert Shuler labeled the outbreak “Mexican Disease.”³

Public health reports characterized the affected neighborhoods as “unclean” and warned infection would spread to white populations.⁵ Employers used the plague as a pretext for layoffs; the Biltmore Hotel fired 150 Mexican workers.³ San Diego officials, meanwhile, set up a fund for rat extermination and planned to guard the county line against movement of Mexican residents out of the affected district.²

One figure pushed back visibly. Nora Sterry, principal of Macy Street Grammar School, bypassed quarantine guards to bring food and organize community events for the quarantined families.³

Demolition of the Macy Street District

Containment escalated quickly beyond quarantine. On November 6, Walter Dickie, secretary of the California Board of Health and head of the medical response, told a Chamber of Commerce meeting that neighborhoods where Mexicans lived should be condemned and destroyed.³ After rodent extermination fell short, city leaders used demolition and fire to obliterate the most affected neighborhoods, and some that were not affected at all. Historian Bill Deverell described the response as “brutal.”⁶

Approximately 2,500 buildings were fumigated or burned down. Roughly half were homes of Mexican laborers. The city provided no compensation and no rehousing, only “get out” orders.³⁶ The campaign was framed as rat eradication but functioned as slum clearance, removing a Mexican neighborhood that city boosters had long found incompatible with their image of Los Angeles as a white tourist destination.

What the Outbreak Left Behind

The 1924 epidemic reshaped parts of Los Angeles that outlasted the disease. County health chief Pomeroy cited a “public demand for the separate treatment of certain diseases which are infectious and prevalent among these people” to justify opening the Maravilla Park Health Center in a Mexican district. Facilities designated for Mexican patients were frequently “inexpensive” and “ramshackle” wooden structures, compared with better-equipped centers for white residents.⁵

The plague response also hardened existing racial-ethnic separations in the city’s physical and social landscape.⁷ Destruction of the Macy Street District cleared the way for development that would reshape the area and effectively erase the neighborhood from the map.

On the public health side, the crisis forced coordination among city, county, state, and federal authorities, produced housing reforms, and launched a comprehensive rodent eradication program credited with preventing plague from spreading to the rest of the city.⁸ After 1925, plague transmission in California shifted from urban rats to wild rodent species in rural and mountainous areas, where the disease remains entrenched.⁹

Where Plague Lives in Los Angeles County Now

Plague has not occurred in an urban or developed area of California in nearly a century.¹⁰ But Yersinia pestis still circulates among wild rodent populations such as California ground squirrels, chipmunks, woodrats, and their fleas, in foothill and mountainous regions across much of the state. Since 1970, plague-positive rodents have been detected in 34 of California’s 58 counties.¹¹ From 1927 through 2020, California recorded 64 human plague cases, most linked to wild rodent contact rather than urban transmission.

In Los Angeles County, the highest-risk areas are the rural recreational and wilderness zones of the Angeles National Forest and the San Gabriel Mountains, where hikers and campers can encounter infected rodents and their fleas.¹² Rats and mice in the urban core are not involved in plague transmission under current conditions.¹⁰

California cases are rare but still occur. In August 2025, a South Lake Tahoe resident tested positive for plague after being bitten by an infected flea while camping and recovered at home with antibiotic treatment. The most recent prior case was in El Dorado County in 2020, also tied to the South Lake Tahoe area. Two cases in 2015 were linked to Yosemite National Park, and those were the first in California since 2006.¹³ Nationally, the CDC reports an average of about seven human plague cases per year, concentrated in two western regions, with over 80% of U.S. cases being the bubonic form transmitted by flea bites rather than the pneumonic form that struck Los Angeles in 1924.⁹

What to Watch For and How It’s Treated

Yersinia pestis causes three clinical forms of disease, each with its own transmission route and severity.

Bubonic plague is the most common form in the U.S., accounting for about 80% of cases. It results from the bite of an infected flea and produces fever, chills, weakness, and painfully swollen lymph nodes called buboes. Untreated, the fatality rate is 30% to 60%.¹⁴¹⁵
Septicemic plague occurs when the bacteria enter the bloodstream, either directly from a flea bite or as a complication of untreated bubonic plague. Symptoms include fever, shock, and tissue death that can turn extremities black.¹⁴
Pneumonic plague is the rarest and deadliest form, developing when the bacteria infect the lungs. It is the only form transmissible from person to person. Without treatment it is virtually 100% fatal, and even with antibiotics mortality remains above 50%. Treatment must begin within 24 hours of symptoms for the best chance of recovery.¹⁴¹⁵

In the modern antibiotic era, overall mortality for plague in the United States is roughly 13%, down from 66% before antibiotics. Patients who receive at least one dose of an effective antibiotic have a mortality rate of about 9%.¹⁶ The CDC recommends starting antibiotics as soon as plague is suspected, without waiting for lab confirmation. First-line drugs in the U.S. include gentamicin and fluoroquinolones such as ciprofloxacin and levofloxacin, with doxycycline also used for bubonic cases. Treatment typically lasts 10 to 14 days.¹⁷ No licensed vaccine is available to the general public.¹⁸

Health officials in plague-endemic parts of California advise people to avoid contact with wild rodents, use insect repellent containing DEET, keep pets leashed and on flea control, and seek medical attention if they develop fever or swollen lymph nodes after visiting wilderness areas. Rodent surveillance in El Dorado County found 41 rodents testing positive for plague exposure between 2021 and 2024 in the Tahoe Basin, with four additional positives in 2025, and officials consider the disease “under control” and treatable with prompt antibiotics.¹³ For an Angeleno, that is the practical picture: plague is a wilderness exposure risk in the mountains to the north and east of the city, not something lurking in a downtown alley.

1
Los Angeles Times. Column One: A Devastating Scourge Exposed the City’s Darkest Impulses
2
San Diego Union-Tribune. In 1924, People Were Dying of Plague in Los Angeles
3
L.A. Taco. Mexican Disease: The 1924 Plague Pandemic
4
Science History Institute. San Francisco’s Plague Years
5
National Library of Medicine. The History of Disease and Disability at the Border
6
USC Dornsife. Historic Plague Parallels With COVID-19 Pandemic
7
UC Press. Plague in Los Angeles, 1924: Ethnicity and Typicality
8
LA City History. Plague Epidemic of 1924
9
Centers for Disease Control and Prevention. Plague Maps and Statistics
10
ArcGIS StoryMaps. Plague in California
11
California Department of Public Health. California Plague Surveillance Compendium
12
Los Angeles Times. Bubonic Plague California Case Near Lake Tahoe
13
El Dorado County. Resident Tests Positive for Plague
14
Centers for Disease Control and Prevention. Plague Signs and Symptoms
15
World Health Organization. Plague Fact Sheet
16
National Library of Medicine. Plague in the United States, 1900–2012
17
Centers for Disease Control and Prevention. Plague Clinical Care
18
National Library of Medicine. Plague Vaccine Development