Investigating Hepatitis E Infection Rates in Bangladesh

Hepatitis E virus (HEV) is a major cause of liver disease, especially in areas with poor access to clean drinking Water like South Asia and Africa. This virus spreads mainly through contaminated water, and the first two types of HEV (HEV-1 and HEV-2) can be deadly for pregnant women. In places like Bangladesh, HEV is a common reason for people needing hospital care for liver issues. Past studies suggest that a significant number of deaths among mothers might be linked to HEV infection.

#The Need for Better Understanding

Even though HEV is a significant health issue, we still don’t know everything about how it spreads or the factors that put people at risk. Efforts to control the spread of the virus through better water and sanitation have not worked as well as hoped. While there is a vaccine available, the World Health Organization (WHO) doesn’t recommend it for regular use due to a lack of solid data on how many people are affected by HEV.

Data on HEV Infections are hard to come by, and predictions about how many people get sick or die from this virus vary widely. Finding out what causes HEV infections and getting better estimates of how many people are affected can help decision-makers at both local and global levels.

#How We Can Measure Infections

Serological data, which looks at Antibodies in blood, can help us estimate how many people have been infected with HEV. This method provides indirect evidence of infection. A strategy is to look at different age groups and see how many people now have antibodies to HEV, which shows they’ve had a past infection. This method has been used before, but it has its challenges. Past studies didn’t always account for how antibodies can fade over time, especially in younger people. Another issue is that they often assumed that the risk of infection is the same for everyone, regardless of age or time.

A better way to measure infections involves taking blood Samples from the same individuals at various points in time. By doing this, we can directly see changes in their serostatus and accurately measure new infections and the fading of antibodies.

#Study Design

In this research, we aimed to learn more about HEV infections by studying a group of 580 households in Bangladesh. The goal was to find out what factors increase the risk of infection and to estimate how often infections occur and how quickly antibodies fade. We also wanted to compare our findings from long-term data with estimates from short-term surveys.

#Recruiting Participants

We collected samples from a large number of people between March 2021 to February 2022. Households were selected using a two-step process. First, the area was divided into smaller sections, and we randomly chose some of these areas to visit based on satellite images. Then, we randomly selected households to approach within those areas. We collected consent from the head of each household and gathered data on individual members about their demographics and water use. Along with this information, we took blood samples from everyone who agreed to participate.

#Testing Blood Samples

Blood samples were tested for antibodies to HEV using specific kits. If a sample showed a certain level of antibodies, it was marked as positive for past infection. Samples with unclear results were not included in the final analysis.

#Analyzing Our Data

We used statistical methods to estimate how many people in the group had antibodies and to analyze what factors might affect these numbers. We created visual maps showing where the antibodies were more common and explored relationships between demographic factors and infection status using advanced statistical models.

#Risk of Infection and Fading Antibodies

We looked at how many previously uninfected people became infected during the study and how many people lost their antibodies over time. To determine the infection rate, we calculated how many new cases occurred during the study and divided that by the total amount of time people were at risk of becoming infected. We did something similar to figure out how fast antibodies faded in those who had previously been infected.

We also developed models to estimate the rate of infection using data from various age groups. In one model, we assumed that once a person got infected, they would always have antibodies. In another model, we accounted for the possibility that antibodies could fade away. We adjusted these models based on our own observations and examined how well they matched with the data we collected.

#The Findings

During our study, we found that 15% of the people tested had antibodies to HEV, indicating past infection. The rates were significantly higher in males compared to females, and we noted that the prevalence increased with age, peaking around 40 years old before leveling off.

When we examined the infection rates, we discovered that about 3% of people who initially did not have antibodies became infected each year, which translates to around 12,500 new infections a year in Sitakunda.

The fading of antibodies was observed as well. About 15% of those who were initially positive became negative during the study period, and this rate was higher in children compared to adults. This means that younger individuals might lose their antibodies more quickly.

#Comparing Methods of Estimation

We also compared estimates of infection rates obtained from our long-term data with those derived from shorter surveys. Traditional methods, which assumed lifelong immunity, produced much lower estimates than our direct observations. When we adjusted for fading antibodies, our estimates were much more in line with what we observed in the long-term study.

This shows that the usual way of estimating infection rates might underestimate the number of infections, especially if they don’t account for different risks based on age or the possibility of losing immunity.

#Implications of Our Findings

Our findings show that HEV is actively circulating in Sitakunda, with specific groups being at higher risk. Those working outside the home and those who reported difficulties accessing clean water were found to be more susceptible to infection.

Given the low rates of reported cases of hepatitis E, understanding infection rates through serological data becomes crucial. While the methods used have their flaws, they offer valuable insights into how many people are getting infected and how the virus spreads.

#Conclusion

Collectively, our research provides a better understanding of how HEV spreads in Bangladesh. We learned that certain occupations and access to clean water significantly affect the risk of infection. Our study highlights the importance of refining the way we collect and interpret data related to hepatitis E. By improving our analytical methods and gathering more longitudinal data, we can gain a clearer picture of this preventable disease and help develop strategies to combat it effectively.