Rising Dengue Fever Cases in Cambodia

Dengue fever is becoming a bigger problem around the world, especially in Cambodia. Over the past twenty years, the number of dengue Cases has jumped eight times. The worst year was 2019, when many people got sick. Experts say this increase is caused by several factors, such as more people living in areas where dengue is common, rapid urban growth without enough mosquito control, better global travel, and changes in the climate that allow mosquitoes to spread further.

To tackle the dengue issue, it is crucial to have accurate numbers on how many people are affected. This helps in deciding how to use resources effectively to fight the infection and care for those who are sick. There are new dengue vaccines being developed, and public health officials want to roll them out in areas where dengue is common. However, many countries struggling with dengue have weak monitoring systems that only capture reported cases, meaning the real number of infections is likely much higher than what is shown in records.

One way to get a better understanding of the real dengue situation is by using data from active monitoring systems. This method involves examining a group of people over time and comparing how many cases they find to the official records. While some studies focus on patients who show symptoms, they miss many people who may have dengue but don’t show any signs or don’t go to a doctor. Including these silent cases is essential for grasping how the disease spreads and how to control it.

In Cambodia, a country with about 17 million people, the last national dengue reports were from 2010. Following improvements in health care after a previous civil war, Surveillance for dengue was better from 1980 to 2007. Since then, however, there have been many changes in the population and how people live. The national monitoring still has limitations, mostly depending on patients to report themselves, and it doesn’t include private healthcare practices. Because of this, the actual number of dengue cases is often underestimated. Past studies indicated that the national reports missed between 3.9 to 29 times more cases than what was actually happening.

To improve our grasp of dengue in Cambodia, it is important to analyze national surveillance data from 2002 to 2020 and relate it to findings from a study tracking children’s health over time.

#National Surveillance for Dengue Cases

The Cambodian National Dengue Control Program collects monthly information about dengue cases from hospitals. Doctors use specific guidelines to identify cases of dengue fever and its severe forms. In limited situations, confirmatory tests are performed, depending on whether patients can afford the tests.

Dengue monitoring started in 2001 with five provinces, and later expanded to ten and then fifteen. Patients receive treatment as per national guidelines.

#Census Data

Data on the population was gathered from the national census carried out in 1998, 2008, and 2019. This information helps to estimate the growth rate of the population.

#Pediatric Cohort Study

A study involving 771 children aged between two and nine years took place to examine how dengue and the body’s immune response were connected. The children were observed every six months from mid-2018 to late 2021. Testing for dengue antibodies was done during this time, and if any child displayed symptoms, they were tested for the disease.

During this period, some children who had no previous dengue antibodies at the start went on to develop immunity later on, indicating they had caught the disease without realizing it. It is critical to identify these silent infections to fully grasp how dengue acts in the body.

#Study Oversight and Ethics Statement

All data collected were anonymous and can be requested from the Cambodian Ministry of Health. Monthly dengue case counts are also available through World Health Organization reports.

#Statistical Analysis

The study analyzed dengue cases reported from January 2002 to December 2020. Researchers calculated the average number of cases and the rates for different age groups using census data. They also examined trends over time to see how ages of infected individuals and the characteristics of the disease changed.

#Nationally Reported Dengue Incidence in Cambodia 2002-2020

From 2002 to 2020, over 350,000 cases of dengue were reported in Cambodia. The average rate of infections was about 1.75 cases for every 1,000 people per year. The most significant outbreaks occurred in the years 2007, 2012, and 2019. The outbreak in 2019 was the largest since records began, with almost 69,000 cases.

The majority of cases happened from June to August during the wet season when the number of mosquitoes increases. The provinces of Siem Reap and Phnom Penh experienced the highest rates of infection.

The analysis of data from the last 19 years shows a steep rise in reported cases, indicating more people are getting infected and suggesting a change in the population affected, leaning more towards older children.

#Changes in Dengue Case Characteristics Over Time

When looking at the data, it was found that the cases were almost evenly shared between boys and girls. The average age of those infected rose from about 5.8 years in 2002 to 9.1 years in 2020. Over the years, there was a noticeable decline in severe cases and deaths from dengue, likely due to improving healthcare and education.

The most common type of dengue virus found was DENV-2, followed by DENV-1, DENV-3, and DENV-4. The type of virus causing outbreaks changed yearly, indicating that the virus evolves or shifts in prevalence over time.

#Comparisons of Data from National Surveillance Data and a Longitudinal Cohort Study

During the pediatric study, 51 confirmed dengue cases were identified among children from mid-2018 to early 2020. The national reports documented fewer cases in the same age group. This comparison revealed that the national data missed a significant number of dengue cases.

In addition to outright cases, many children had dengue without showing symptoms. This finding points to a substantial underreporting issue.

#Conclusion

Cambodia is going through many changes, and this influences how dengue spreads. In the last two decades, the number of people getting infected has more than doubled, and more older children are being affected than before. While the national data seems to underestimate the cases, the good news is that the severity and mortality rates from dengue have declined.

To successfully manage dengue, it is essential to improve the accuracy of infection data by combining different types of surveillance to better target control measures and vaccination campaigns in the future. This will help ensure that vulnerable Populations can be protected effectively against dengue disease.