Disease outbreak in Los Angeles, California
The 1924 Los Angeles pneumonic plague outbreak was an outbreak of the pneumonic plague in Los Angeles, California that began on September 28, 1924, and was declared fully contained on November 13, 1924. It represented the first time that the plague had emerged in Southern California since plague outbreaks had previously surfaced in San Francisco and Oakland. The suspected reason for this outbreak was a rat epizootic where squirrels that were found to be plague infected were secondarily infected by rats. Due to the evidence of infected squirrels near San Luis Obispo County as late as July 1924 and the migration habits of both squirrels and rats, it is thought that squirrels were the original source of the plague outbreak in Los Angeles.
The outbreak killed 30 people and infected several more. Public health officials credited the lessons learned from the San Francisco outbreak with saving lives, and swiftly implemented preventative measures, including hospitalization of the sick and all their contacts, a neighborhood quarantine, and a large-scale rat eradication program. The epicenter of the plague was in the Macy Street District, primarily home to Mexican immigrants, which was also known as "Little Mexico". Racism against Mexican Americans tainted the reaction to the plague, an issue not made public until the outbreak concluded. This outbreak was the last instance of aerosol transmission of the plague and the last major plague outbreak in the United States.
Background.
During the 1920s, thousands of Mexicans crossed the border to work on large plantations that thrived on "cheap, compliant labor". The large plantation owners supported open immigration, because Mexicans were thought of as "docile and backward". However, immigrants faced a backlash from labor unions which supported increased border security and often expressed racists tendencies towards Hispanic immigrants due to the belief that cheap labor on plantations would favor immigrants instead of American workers. In addition, Hispanics also had to face the stereotype of spreading crime and disease, and some worried that they refused to assimilate into white America. As a consequence, Hispanics were often "physically isolated from the white" communities of Los Angeles. At the time, roughly 19% of Los Angeles residents were foreign born, 22,000 of which were Mexican.
At the time, Los Angeles, being the largest city on the West Coast and the fifth-largest in the country, was growing on an economy primarily reliant on its flourishing tourism industry, a "land boom," and a new harbor. An ideal climate allowed its population to explode in the early 20th century: it grew by 80.66% between 1910 and 1920 and by 114.69% between 1920 and 1930.
Mexicans in Los Angeles mostly settled in Eastern Los Angeles and unincorporated territory of Los Angeles County, primarily in two neighborhoods – known by white residents as ghettos – Belvedere and the Macy Street District. In the Macy Street District, named for its southern boundary of Macy Street (now Cesar Chavez Avenue), roughly 3,000 residents were surrounded by the Los Angeles River, polluted by dead carcasses and brick, coal, gas and meatpacking plants. It was a more rural feeling area where chickens and other farm animals ran free. The rat population also thrived on the prevalence of horse and mule yards. Residents were crammed into one-fifth of a square mile, living in cramped residences with high rent despite low-quality living conditions. Residents often had to travel through someone's else's apartment to get to their own room. Despite often illegal living conditions, no investigations into the Macy District's living conditions was ever held, and the only four paved roads into the District were never inspected by the Department of Streets and Sanitation. Many papers rarely bothered to report on the area and when they did it was to describe crime or recount comical tales of citizens chasing chickens around Clara Street.
Timeline.
September 1924.
On September 28, 1924, in the Macy Street District (present day Los Angeles Chinatown) of Los Angeles, California, a 51-year-old man named Jesús Lajun fell ill with a fever and a painful lump in his groin. Prior to the onset of symptoms, Lajun had discovered a decaying rat under his house and picked it up to throw into the trash. A physician initially diagnosed Lajun's pneumonic plague as a venereal disease (sexually transmitted infection), due to his enlarged lymph node.
Even after the Los Angeles City Health Officers' eventual confirmation of the disease as the pneumonic plague, the disease was not referred to by its name. 
Investigators initially believed that Lajun had contracted the bubonic plague. Left untreated, the bubonic plague can move to the lungs and cause a secondary pneumonic infection, with a mortality rate of 40–60%.
As Lajun's condition worsened, he developed extreme symptoms such as bloody sputum, causing physician to believe it converted into pneumonic form. Because he was the first with identifiable symptoms of the plague, Lajun was designated the index patient.
October 1924.
In the same week, on October 3, 1924, Jesús Lajun's fifteen-year-old daughter Francisca also fell ill, complaining of fever and shortness of breath. Both Lajun and his daughter also had sore throats and back pain. Dr. Giles Porter, a physician of the Los Angeles City Health Office, was called to the house and diagnosed Francisca with lobar pneumonia, a form of pneumonia weakening the lobe of a lung due to inflammatory exudate between alveoli. Dr. Porter initially diagnosed Lajun's plague as a venereal disease, or sexually transmitted infection, due to his enlarged lymph node. Following the Lajuns' diagnosis, they were treated by Lucina Samarano, a pregnant nurse. Samarano lived at 742 Clara Street (Bing Map), which would become the eventual epicenter of the outbreak.
However, neither of the Lajuns recovered. Francisca died in an ambulance on its way to Los Angeles County General Hospital after her symptoms worsened. An autopsy of Francisca performed by pathologist Webb ruled her cause of death as double pneumonia. Jesús Lajun died on October 11, with his cause of death ruled as bronchopneumonia.
Meanwhile, Lucina Samarano developed similar respiratory symptoms and died days later on October 15. No autopsy was conducted on Samarano however, she had been diagnosed as having acute myocarditis, or inflammation of the heart muscle. Samarano was six months pregnant when she first got sick, and delivered a stillborn baby boy shortly before she died. Her body was returned to her husband Guadalupe Samarano, who later developed infection and died within days.
Between October 15 and 19, Father M. Brualla, a Catholic priest who had administered last rites to the affected people and held the requiem mass for Samarano, developed the same respiratory symptoms and died days later, as did several attendants of Samarano's funeral. Many of the Samaranos' friends and family were unknowingly infected by Guadalupe Samarano, and within a week, the plague killed his entire family of eight.
On October 22, Guadalupe and Jessie Flores, neighbors of the Samaranos, also fell ill with symptoms of the pneumonic plague and were subsequently hospitalized at the General Hospital. On October 24, physicians again misdiagnosed the Flores with severe pneumonia as there was no known connection at the time between the Flores and Samaranos.
On October 26, Guadalupe Flores died and received an autopsy by pathologist Lawrence Parsons, who misruled his cause of death as double pneumonia. No bacterial culture was conducted to correctly identify the cause of his pneumonia as "Yersinia pestis", the causative agent of the pneumonic plague. Flores' body was returned to his family on October 27, exposing them to the bacteria. Afterwards, the hospital's morgue staff was quarantined for five days.
On October 28, physician George Stevens reported an unknown, highly contagious disease to the hospital and recommended the construction of a quarantine ward after he and physician Dr. Elmer Anderson both treated patients in unusually critical condition. That same day, brothers Mike and Jose Jiminez also fell ill and vacated 742 Clara Street, the residence of the Samaranos, exposing the rest of the district to the plague.
On October 29, several people who were in close contact with the Samaranos contracted the plague, including Mary Costello, Guadalupe Samarano's nurse; Fred Ortega, who lived at 742 Clara Street; Samarano's mother, Maria; and his brother, Victor. Maria and Victor Samarano were hospitalized under Dr. Bogen's supervision after exhibiting suspected symptoms of avian influenza. Jesus and Maria Valenzuela, cousins of the Samaranos, also fell ill with symptoms of the plague, though they were not traced back to the Samaranos. The Samaranos' children, Alfredo, Gilberto, Raul, and Roberto, along with six others, were hospitalized and diagnosed with meningitis, despite their skin turning black, a pathognomonic symptom of the plague. A physician also requested an ambulance from the hospital for two patients in critical condition and were highly contagious.
On October 30, the Los Angeles County Hospital pathologist George Maner finally identified the pneumonic plague as the disease causing the outbreak and notified the Los Angeles City Health Department and state officials. Maner identified it from a blood serum sample from a patient who died after attending Lucena Samarano's funeral. Interestingly, Maner had never worn gloves during autopsies, but immediately began to once he detected the pathogen. City health officials quarantined an eight-block area encompassing Clara Street, where the funeral had taken place, as well as a six-block area in Belvedere after Jesús Lajun was identified as the index case, but did not announce the causative disease of the outbreak. ;ref name="Feldinger 2008 [URL] 51" ; ;/ref ; Thirteen more cases of an unknown disease were admitted, all of whom developed cyanosis and hemoptysis, or bloody sputum, the former of which is indicative of low oxygen saturation of tissues near the skin surface. Three of the patients died the same day, and in response the pneumonic plague was first suggested as the cause of the outbreak. The following morning, the diagnosis of pneumonic plague was confirmed by pathologists after an autopsy reported gram-negative bipolar staining bacilli resembling the plague.
On October 31, the United States Public Health Service and California State Board of Health learned of the diagnosis indirectly from telegrams sent from the assistant superintendent of the hospital. The telegram was sent to federal and state authorities and medical supply dealers to explore where vaccines or serums to the plague could be found. However, the antiserum requested was produced solely by the H.K. Mulford Company laboratories in Philadelphia, a 3,141-mile journey which would require automobile transport to Mineola, New York then a flight by mail plane to Los Angeles with a stopover in San Francisco. With cooperation from the United States Post Office Department and its respective air mail officials, it was prepared within an hour, according to the company. In a promotional literature release by Mulford Laboratories, a producer of the serum, stated that the serum was delivered within 36 hours, would stop the "Swath of Death", and "save the lives of thousands".
The same day, County Health Commissioner J. L. Pomeroy imposed a quarantine around midnight, with 75 police officers and 200 armed World War I veterans deployed to assist quarantine guards in enforcing the quarantine, who often looted from local residents and businesses. The guards ruled vigilantly in the quarantined district and shot stray dogs, cats, chickens, and more in an attempt to eradicate animals that could potentially be plague-infected.
November 1924.
On November 1, Benjamin Brown, a United States Public Health Service surgeon in Los Angeles, warned the United States Surgeon General Hugh S. Cumming of the outbreak and Yersin's request for an antiserum. Brown's transmission was encoded, referring to "pneumonic plague" as "ekkil", "suspected cases" as "suspects", "deaths" as "begos", and "situation bad" as "ethos":
 ;templatestyles src="Template:Blockquote/styles.css" / ;Eighteen cases ekkil. Three suspects. Ten begos. Ethos. Recommend federal aid
Cumming then alerted Senior Surgeon James Perry, who was then stationed in San Francisco, to confidentially investigate the outbreak, attempting to avoid gratuitous involvement in state and municipal affairs.
10 more fatalities were recorded, and Pomeroy extended the quarantine to encompass the entire Macy Street District, purportedly to ensure that "Mexicans who we feared would scatter" couldn't evade the original quarantine. The border's boundaries were closed to regular vehicle traffic and guards were positioned at every home with suspected cases. Agricultural and railroad workers were exempted from the quarantine. A temporary laboratory was constructed by the Los Angeles City Health Department in the quarantined area to quickly identify new cases. By this time, the cause of the outbreak had been definitively established as the pneumonic