The Rise of Aedes-Borne Diseases in Colombia

Dengue is a disease that mainly affects tropical and subtropical areas. In the last 50 years, the number of dengue cases has increased significantly, reaching about 6.5 million cases in 2023. This disease is caused by four different types of viruses, and it is spread by Aedes mosquitoes. Controlling dengue is challenging, and outbreaks happen periodically. Over the years, countries that regularly deal with dengue have also seen the rise of other diseases spread by these mosquitoes, such as Chikungunya and Zika. This has made it harder for health services to manage and respond to these diseases.

#The Spread of Aedes-Borne Diseases

Dengue, chikungunya, and Zika are linked to factors that influence how many mosquitoes are present and their ability to spread disease. These factors include the climate, the amount of vegetation, and sanitation conditions. As temperatures rise due to climate change, dengue is also spreading to areas that were previously not affected. Urban areas with high populations and vulnerable communities are at a greater risk for these diseases because mosquitoes thrive near humans.

Due to the fact that these diseases share the same mosquito vector and often occur together, it makes sense to study them together. In Colombia, researchers used special statistical methods to identify areas where dengue, chikungunya, and Zika cases were occurring at the same time. They found regions where all three diseases were present, as well as areas where only one or two diseases were reported. This suggests that certain factors such as humidity and sanitation can affect the spread of each disease in different ways.

#Research Methodology

To study the outbreaks of dengue, chikungunya, and Zika in Colombia, researchers used a joint statistical model. This model looked at the risk and likelihood of each disease happening at the same time and examined how they relate to other factors. This research used health data from the years 2014 to 2016 across the country's Municipalities.

Colombia is located in northern South America and has many different geographical features. The country is divided into 1,121 municipalities, each with different climates and environmental conditions. Researchers gathered data on dengue, chikungunya, and Zika cases from a national health surveillance system. This data included individuals who were diagnosed with these diseases in healthcare facilities.

They also collected environmental data for the same period, including information on vegetation, average temperature, humidity, and rainfall. Population estimates and socioeconomic information were taken from national statistics. These variables were then analyzed to understand how they related to the presence of the diseases.

#Statistical Models Used

Researchers applied a specific statistical model to estimate the relative risk of Aedes-borne diseases and the likelihood of each disease occurring. The model assumed that the number of expected cases is uniform across all municipalities, and looked at how various factors impacted the risk and presence of these diseases. The data showed how outbreaks of dengue, chikungunya, and Zika varied by municipality.

#Key Findings

From January 2014 to October 2016, there were almost 440,000 reported cases of dengue, chikungunya, and Zika in Colombia. The rates of dengue were highest, followed by chikungunya and Zika. This shows that dengue is the most prevalent among the three diseases, likely due to its long-standing presence in Colombia.

The data indicated that certain regions of Colombia had a higher risk of experiencing Aedes-borne diseases. These areas included southern Andean regions, valleys, and near the Caribbean coast. Higher risks were often found in municipalities with higher population density and urbanization.

When looking at the probability of each disease occurring, dengue was found to be more likely present than chikungunya or Zika in most municipalities. However, in certain regions with more social vulnerability, chikungunya had a higher probability of occurring compared to the other diseases.

#Environmental Factors Influencing Disease Spread

One of the most important factors identified in the research was temperature. The study found that warmer temperatures were associated with a higher risk of Aedes-borne diseases. This is because rising temperatures can speed up the lifecycle of mosquitoes and the viruses they carry. Additionally, areas with more vegetation had a positive association with the spread of these diseases, suggesting that mosquitoes thrive in such environments.

Humidity and rainfall were also related to the spread of Zika, with increased humidity leading to a higher likelihood of Zika cases in comparison to dengue and chikungunya. However, population density alone didn't have a clear link to the risk of Aedes-borne diseases.

In terms of sanitation, municipalities with better garbage collection services showed a higher risk of Aedes-borne diseases. However, this might not mean that waste is properly disposed of, and open pits can still provide breeding sites for mosquitoes.

#Socioeconomic Factors and Healthcare Access

The research also looked at socioeconomic indicators, finding that areas with a higher percentage of homes with garbage collection faced a greater risk of Aedes-borne diseases. In contrast, places with more socioeconomic vulnerability tended to have fewer cases overall.

Interestingly, the access to healthcare was found to be associated with the risk of these diseases. Municipalities with better healthcare access reported more cases, likely due to better reporting and diagnosis capabilities. However, those with real access to healthcare had a higher chance of detecting Zika compared to dengue and chikungunya.

#Conclusion

The study presents a comprehensive look at how dengue, chikungunya, and Zika are spreading in Colombia and the various factors that influence their outbreaks. It highlights the importance of using joint statistical models to understand and track these diseases together.

The results indicate that while dengue remains the most prevalent disease, chikungunya has a significant presence in socially vulnerable areas. Furthermore, temperature and vegetation are key drivers of these diseases, emphasizing the need for targeted public health strategies that consider local conditions and socioeconomic factors.

By examining these Aedes-borne diseases together, public health officials can better plan interventions that address multiple diseases simultaneously, particularly in regions that are at high risk. This research provides valuable insights that can be applied to other regions facing similar health challenges, helping to improve surveillance and response strategies against these mosquito-borne diseases.