Spanish Flu: Symptoms, Types, Causes and Treatment

The Spanish flu pandemic of 1918–1919 remains one of the most devastating disease outbreaks in human history. Despite the passage of a century, its legacy continues to inform our understanding of pandemics, viral transmission, and public health responses. In this article, we explore the Spanish flu’s symptoms, types, causes, and treatments, piecing together insights from historical records and modern research.

Symptoms of Spanish Flu

The symptoms of the Spanish flu were both typical and unusually severe compared to seasonal influenza. Understanding these symptoms is crucial, not only for historical perspective but also for recognizing patterns in future pandemics.

Symptom	Prevalence	Severity	Source(s)
Fever	Very common	High	3 8
Cough	Very common	Persistent	3 8
Malaise	Widespread	Severe fatigue	3 8
Headache	Frequent	Intense	3 8
Myalgia (aches)	Frequent	Severe	3 8
Cyanosis	Occasional	Often fatal	3 8
Pneumonia	Common	Life-threatening	4 8

Table 1: Key Symptoms of Spanish Flu

The Clinical Picture

Spanish flu typically began with sudden onset of high fever, chills, headache, and profound muscle aches. Patients often complained of intense fatigue and malaise, which could be debilitating. A dry, persistent cough followed, sometimes accompanied by sore throat and chest discomfort 3 8.

Severe and Unusual Manifestations

What set the Spanish flu apart was the rapid progression to severe respiratory distress. Many patients developed cyanosis—a bluish discoloration of the skin and lips—indicating dangerously low oxygen levels. This signaled the onset of viral or secondary bacterial pneumonia, which was often fatal, especially since antibiotics were not yet available 4 8.

The W-Shaped Mortality Curve

Unlike typical flu outbreaks, which mainly threaten the very young and old, the Spanish flu showed a “W-shaped” mortality curve. There was unusually high death among healthy young adults, along with the usual peaks in infants and the elderly. This led to unique social and demographic impacts 2 8.

Complications and Recovery

Serious complications included secondary bacterial pneumonia, acute respiratory distress syndrome, and, in some cases, multiple organ failure. Recovery, when it occurred, could be prolonged, with persistent fatigue and respiratory symptoms lasting weeks or months 4 8.

Types of Spanish Flu

The 1918 influenza pandemic is often referred to as a single event, but it was actually marked by distinct waves and variations in clinical severity. Recognizing these types helps us understand how pandemics can evolve and spread.

Wave/Type	Timeline	Characteristics	Source(s)
First Wave	Spring 1918	Mild, typical flu	3 8
Second Wave	Autumn 1918	Severe, high mortality	3 8
Third Wave	Early 1919	Intermediate severity	3 8
Secondary Pneumonia	Any wave	Bacterial complication	4 8

Table 2: Types and Waves of Spanish Flu

The Three Waves

The Spanish flu pandemic is classically described as having three major waves:

• First Wave (Spring 1918): The initial outbreaks were relatively mild. Symptoms resembled typical seasonal influenza, with lower mortality rates 3 8.
• Second Wave (Autumn 1918): The deadliest phase. The virus mutated and struck with unprecedented ferocity, causing rapid-onset pneumonia and high death rates, particularly in young adults 3 8.
• Third Wave (Early 1919): The final major wave was less severe than the second but still caused significant illness and death 3 8.

Variations in Severity and Geography

• Mortality rates varied widely by region, influenced by factors such as population density, war-related troop movements, and underlying health conditions like tuberculosis 8.
• Some outbreaks were complicated by a high incidence of secondary bacterial pneumonia, which was the leading cause of death in many cases 4 8.

Mutation and Evolution

The virus’s ability to mutate between waves likely contributed to changes in virulence and transmissibility. Such shifts are a hallmark of influenza pandemics and a reason for ongoing vigilance 2 8.

Causes of Spanish Flu

Grappling with the causes of the Spanish flu means looking at both the biological origins of the virus and the social circumstances that allowed it to spread so widely.

Cause/Factor	Description	Impact Level	Source(s)
H1N1 Influenza A	Novel avian-origin virus	Primary	1 3 8
War/Migration	Troop and refugee movements	Amplified	3 8
Poor Sanitation	Overcrowded, unsanitary conditions	Amplified	3 8
Lack of Antibiotics	No treatment for pneumonia	Fatal	4 8

Table 3: Main Causes and Contributing Factors

The Virus Itself

The primary cause of the Spanish flu was a novel H1N1 subtype of the influenza A virus, which emerged via genetic reassortment between avian and possibly swine hosts 1 3 8. Its unique genetic makeup made it highly contagious and capable of causing severe disease.

Environmental and Social Factors

• World War I: The movement of troops, crowded military camps, and mass migration created ideal conditions for viral transmission 3 8.
• Poor Healthcare Infrastructure: Medical care was rudimentary, and hospitals were quickly overwhelmed 3 8.
• Malnutrition and Pre-existing Disease: Populations weakened by war, food shortages, or tuberculosis were more susceptible to severe outcomes 8.

Secondary Bacterial Infections

Most deaths were not due directly to the virus but to secondary bacterial pneumonia, for which there was no effective treatment at the time 4 8. The lack of antibiotics meant that even healthy young adults could succumb rapidly once their lungs became infected.

Potential Role of Environmental Mutagens

Some research suggests external factors—such as increased UV radiation from sunspot activity and high CO₂ emissions—may have contributed to viral mutations, though this remains a topic of scientific debate 1.

Treatment of Spanish Flu

Medical responses to the Spanish flu were shaped by the era’s limited technology, creativity, and resourcefulness. While there was no cure, various strategies were employed to manage symptoms, prevent complications, and reduce transmission.

Treatment	Method/Approach	Effectiveness	Source(s)
Supportive Care	Rest, fluids, nutrition	Essential, variable	3 8
Convalescent Plasma	Antibodies from survivors	Reduced mortality	4
Open-air Therapy	Sunlight, fresh air	Reduced transmission	5
Hygiene/Isolation	Masks, disinfection, spacing	Preventive	5
Osteopathic Care	Manual therapy, advice	Historical reports	6
Homeopathy	Symptom relief, prevention	Anecdotal	7
Pharmaceuticals	Salicylates, codeine, etc.	Limited, palliative	8

Table 4: Treatments Used During the Spanish Flu

Supportive and Symptomatic Care

With no antiviral drugs available, most patients received supportive care—bed rest, fluids, and a nutritious diet. Medications like salicylates (for fever), codeine (for cough), and camphor oil were used to ease symptoms, but their effectiveness was limited 8.

Passive Immunization: Convalescent Plasma

Some hospitals transfused blood products from recovered patients to those severely ill with influenza pneumonia. Evidence from eight historical studies suggests that early administration of convalescent plasma reduced mortality in hospitalized patients 4. However, these studies had methodological limitations, and this treatment was not widely available.

Open-Air Treatment and Hygiene

Records from open-air hospitals showed that fresh air, sunlight, strict hygiene, and the use of reusable face masks helped reduce deaths and transmission among patients and staff. These non-pharmaceutical interventions were notably effective in some settings and remain relevant in pandemic planning today 5.

Manual and Alternative Therapies

• Osteopathic Manipulative Treatment (OMT): Early osteopathic physicians used manual techniques alongside lifestyle advice, though scientific evidence for effectiveness is limited by the era’s research standards 6.
• Homeopathy: Some practitioners reported success with homeopathic remedies, but these reports are anecdotal and not supported by modern clinical trials 7.

Vaccines and Antibiotics

No effective vaccine was available during the pandemic, and antibiotics for secondary bacterial infections were not discovered until decades later. Primitive anti-pneumococcal vaccines and immune sera were tried, but with modest results 8.

Conclusion

The Spanish flu pandemic taught the world hard lessons about viral pandemics, healthcare limitations, and the importance of public health measures. Its legacy lives on in the strategies we use to combat emerging diseases.

Key Takeaways:

• Symptoms: Spanish flu caused sudden, severe symptoms, with high rates of pneumonia and death among young adults as well as the very young and old 3 8.
• Types: The pandemic unfolded in multiple waves, with the second wave being the deadliest due to viral mutation and increased virulence 3 8.
• Causes: A novel H1N1 influenza virus, combined with global war, mass migration, and limited medical care, fueled the spread and high mortality 1 3 8.
• Treatment: Care was mostly supportive, with some benefit from convalescent plasma. Hygiene, open-air therapy, and other interventions reduced transmission and mortality in certain settings 4 5 6 7 8.

By studying the Spanish flu, we not only honor those who suffered but also equip ourselves to better face future pandemics—armed with both historical wisdom and scientific progress.