Google Trends and Syphilis

J Clin Aesthet Dermatol. 2024;17(12):28–31.

by Theodore Rosen, MD, and Maci Terrell, BA

Dr. Rosen and Ms. Terrell are with the Dermatology Department, School of Medicine at Baylor College of Medicine in Houston, Texas.

ABSTRACT: Objective: This study aims to assess the correlation between Centers for Disease Control-reported syphilis incidence rates and case burden and public interest in syphilis as indicated by Google search trends.

Methods: This study utilized Google Trends data to analyze popular syphilis-related search terms from 2013 to 2023. The latest Centers for Disease Control-reported syphilis incidence rates for 2022 were compared to Google Trends data to identify patterns or correlations.

Results: Google Trends data showed a 37.65-percent increase in average annual searches for syphilis-related terms in the United States from 2013 to 2023. The largest increase in search volume was observed from 2021 to 2022, with a 14.09 percent rise. Mississippi had the highest ten-year average for syphilis-related search terms (97.9). Arkansas, Oklahoma, Mississippi, Nevada, and Louisiana were among the top ten highest reported primary and secondary syphilis rates and were among the top ten states with the highest Google Trends search volume. Texas was the only state to be in the top ten highest Google Trend searches and among the top states with the highest reported absolute number of cases.

Limitations: Limitations include the inability for Google Trends analysis to provide absolute search volumes and limited transparency in its algorithm. Additionally, the study relies on data collected from internet users and may potentially exclude individuals without internet access.

Conclusion: The findings suggest that while public interest in syphilis is increasing overall, there may still exist disparities in awareness and education across different regions of the United States.

Keywords: Syphilis, infectious disease, public health, centers for disease control, google trends, sexually transmitted disease

Introduction

The early history of dermatology is distinguished by its close relationship with venereal disease, particularly syphilis. In the late 1800s, the public health risk posed by syphilis in the United States (US) rose to prominence due to its pervasive and devastating impact.¹ Dermatologists at the time were among the first to care for these patients, gaining expertise in sexually transmitted diseases.¹ The enduring bond between dermatology and syphilis was solidified by the first specialized dermatologic journal published in the United States, the American Journal of Syphilology and Dermatology.²

While public health programs led to a near 90-percent decline in both primary and secondary (P&S) syphilis between 1990 and 2000, reaching a historic low in 2001, the US has since experienced an annual increase in syphilis cases.^3,4 In 2022, the US reported the highest number of cases since 1950, with 207,255 cases of syphilis of all stages, up 17.3 percent from 2021.⁴ 

Despite similar transmission factors, such as increased ease of partner acquisition and altered behavior patterns related to relaxed moral standards, neither gonorrhea nor chlamydia has experienced as dramatic an increase as syphilis in the US.⁵ This increased rate of syphilis raises the question of why alone syphilis is experiencing a resurgence.

Google Trends is an accessible tool that allows users to analyze Google search queries in real time across various languages and countries. It can provide invaluable insight into specific populations in relation to individual behavior as well as major public health trends.⁶ In fact, various studies have utilized Google Trends as a tool for surveilling infectious diseases such as COVID-19, Lyme disease, and influenza.^7–9 Considering the widespread use of search engines as a means for lay people to gather health information, aggregate search engine data could be utilized in investigating and monitoring interest in and knowledge about syphilis in specific regions across the US. 

The study will evaluate whether there is overlap between the most current Centers for Disease Control and Prevention (CDC) reported incidence of syphilis and public internet inquiry by specific populations searching for information related to this resurgent sexually transmitted disease. The key question to ask is: are the people at the highest contemporary risk for syphilis searching for information online—suggesting that some elements of public health education might be working? Or, is the converse true: are those at highest risk not conducting searches for information online—suggesting that there are serious deficiencies in the efficacy of public health educational efforts?

Methods

Data source. The Google Trends software offers data relative to the peak popularity of a specific search term for a given time frame. Search terms must surpass a frequency threshold in order to appear in search term results. Data values for specific terms does not represent an absolute number of search volume, but is normalized and presented on a scale from 0 to 100. Changes in interest over time, as well as variations in interest across regions, are indicated by values between 0 and 100, with a value of 50 indicating that a search was half as popular and 100 denoting peak popularity. The values for the same search term may vary depending on the selected time period of interest. Google Trends generates related terms that are frequently searched for, assigning these related terms values for a specific time period. 

Study population. We evaluated public inquiry in syphilis by reviewing online searches publicly available on Google Trends program. We completed query search on September 22, 2023, for searches in the US for terms related to the word “syphilis,” including: “what is syphilis?” and “syphilis symptoms” from 2013 to 2023. After searching for our terms, Google Trends graphed the popularity of search terms from 2013 to 2023 by US state. Published CDC and Prevention STI Surveillance data from 2022, the most recently available year of surveillance data, were compared to the graph for each search term. 

Ten-year national data on Google trend searches. The annual national data on Google Trend searches is provided as Google Trend data index. The data is reported in a normalized value between 0 and 100 where, 100 is peak popularity of a search term and a value of 50 means the term is half as popular. The average annual search (Table 1) was lowest in 2013 at 53.58, reaching a peak in 2023 at 73.75. Overall, from 2013 to 2023, there was a significant increase in the average annual searches by 37.7 percent for syphilis related terms. The annual percent change in syphilis related searches saw the largest increase from 2021 (59.58) to 2022 (68) at 14.09 percent, while the largest reduction in searches occurred from 2015 (57.25) to 2016 (55.58) at -2.92 percent. 

Top ten states by Google trends data. Analysis of Google Trends data over the past ten years (Table 2) revealed the top ten states in the US with the highest ten-year average for syphilis related search terms were Mississippi (97.9), Louisiana (89.1), District of Columbia (80.5), Texas (79.8), Alabama (76.6), Nevada (76.4), Alaska (76), Oklahoma (75.9), Arkansas (74.8) and West Virginia (73.3). The five states with the highest CDC-reported primary and secondary syphilis incidence rates that are also among the top ten states by Google Trends searches are Arkansas (32.9 per 100,000), Oklahoma (31.8 per 100,000), Mississippi (31.1 per 100,000), Nevada (28.4 per 100,000), and Louisiana (26.7 per 100,000). However, there were five states listed in the CDC top ten highest primary and secondary syphilis by rates that were not found in the top ten Google Trends searches: South Dakota, New Mexico, Arizona, Montana and Oregon. Notably, the top two states with the highest reported primary and secondary syphilis by rate per 100,000 population, South Dakota (84.3 per 100,000) and New Mexico (36 per 100,000) were not found among the top ten states based on Google Trends searches. With regards to CDC-reported raw number of primary and secondary syphilis cases, Texas was the only state among the top ten states that was also listed in the top ten states based on Google Trend searches. High primary and secondary syphilis case load states which were not found to be high sources of Google Trends searches included: California, Florida, New York, North Carolina, Ohio, Georgia, Arizona, Washington and Illinois. 

Discussion

The analysis of Google Trends data provides valuable insights into public interest and awareness of syphilis over the past decade. The substantial increase in average annual searches from 2013 to 2023 suggest a growing overall interest in syphilis, possibly indicating an increased awareness or concern regarding the disease. According to the CDC, 207,225 cases of all-stages syphilis was reported in the US in 2022, an increase by 80 percent since 2018.⁴ Across genders, the rate of primary and secondary syphilis is highest among men (26.8 per 100,00) compared to women (8.7 per 100,000). However, the national rate of infectious syphilis among women substantially increased by 19.2 percent from 2021 to 2022. This dramatic rise has occurred concurrently with increased in rates among men who have sex with women (MSW), suggesting an increase in heterosexual syphilis transmission. Additionally, the CDC reported men who have sex with men (MSM) are disproportionately impacted by syphilis, making up nearly half (45.1%) of all male primary and secondary syphilis cases in 2022.⁴

Comparing states with the highest CDC-reported syphilis incidence rate to those with the highest Google Trend searches revealed insights into potential degrees of public awareness. States such as Arkansas, Oklahoma, Mississippi, Nevada, and Louisiana ranked highly in both CDC reported syphilis rates and Google Trends searches, suggesting a correlation between disease concentration and public interest. This further suggests that there may be increased public awareness in these state populations and the likelihood of effective targeted public health educational efforts. Conversely, states like South Dakota, New Mexico, Arizona, Montana, and Oregon which have high CDC-reported incidence rates but were not found among the top ten highest states on Google Trend searches, suggest a disparity in public interest and awareness of syphilis. It is even more noteworthy that the two states with the highest reported syphilis rates, South Dakota and New Mexico, were not found in the list among the top ten Google Trends Searches. This finding suggests there could exist a lower public interest or awareness for syphilis in these regions and the need for expanded or improved targeted public health education. The latter might, for example, include increased sexual health education in high schools, increased radio/television public service announcements regarding syphilis, more free or low cost public health screening centers, and enhanced availability of barrier protection devices (free condoms).

In regard to reported syphilis cases, Texas was the only state among the top ten states with the highest reported CDC number of cases of infectious syphilis that also ranked in the top ten Google Trends searches. This would suggest that Texas has initiated effective public health initiatives to increase its citizens’ awareness of and knowledge about syphilis infection through media campaigns and health services. Perhaps some of the educational programs might be emulated by other high syphilis incidence states where Google Trend searches do not suggest a high degree of public awareness.

Several factors have been proposed to contribute to the resurgence of syphilis. These include: easily accessible dating apps which facilitate casual sexual encounters, altered behavior patterns due to relaxed societal moral standards, inconsistent condom use, availability of drugs to combat erectile dysfunction, and the use of drugs and alcohol during sexual interactions.^10–14 Additionally, the number of individuals with HIV and syphilis coinfection has risen in recent years. Advancements in HIV treatment and prevention have led to a perception that HIV is not as serious an infection, thus leading to decreased adherence to safer sex practices.^15,16 Even among the elderly, the commonality and proximity of partners in retirement communities, the emergence of dating apps targeting mature individuals, the availability of medical treatment for erectile dysfunction and the reduced fear of pregnancy have all contributed to rising cases in the older age group.¹⁷

Many regions have begun initiating strategies to curtail the rise of syphilis. Methods of combatting this rise include increasing disease screening, contact tracing, patient and provider education, and improved treatment availability.^18–20 San Francisco sought to reduce the increased sexual risk behaviors encouraged by pharmaceutical company advertisements for medication such as Viagra and HIV Antiretroviral through partnership with the U.S. Food and Drug Administration (FDA) to remove unrealistic expectation from media.^21,22

With the resurgence of a disease once commonplace in dermatologic practice, the return of syphilis has necessitated a renewed focus on venereal education in dermatology. Dermatologists are uniquely positioned, to recognize early mucocutaneous syphilis manifestations across age groups, and can play a pivotal role in early detection and management.

Limitations. Limitations of this study include the inability for Google Trends analysis to provide absolute search volumes and limited transparency in its algorithm. Additionally, the study relies on data collected from internet users and may potentially exclude individuals without internet access. This analysis is limited to only correlational findings and does not establish causation between syphilis and internet search engine behavior.

Conclusion

This study identifies a relationship between Google Trends searches and CDC reported syphilis rates. The correlation between CDC reported syphilis rates and state-specific Google searches reveal online search behavior partially reflects regional syphilis occurrence. Alternatively, Google Search trends data and CDC reported incidence may reflect decreased regional awareness for syphilis in some areas. Ultimately the findings reveal the potential for Google trends to monitor public interest and awareness of syphilis and allows for targeted public health strategies in syphilis resurgent regions. 

Acknowledgements

We would like to give special thanks to everyone who helped with editing and providing feedback in writing the manuscript.

Data citation

Google Trends (https://google.com/trends)

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