This is a very interesting paper and I made a quick summary,

Risk associations of submicroscopic malaria infection in lakeshore, plateau and highland areas of Kisumu County in western Kenya

The main findings of the study on submicroscopic malaria infection in western Kenya are as follows:

1. The study found that blood smear microscopy, which is commonly used for malaria diagnosis, exclusively identified P. falciparum infections, while RT-PCR identified P. malariae and P. ovale mono-infections and co-infections with P. falciparum.
2. The routine microscopy method severely underestimates the burden of infections, as submicroscopic infections may act as a reservoir of infectious gametocytes and can develop into clinical infections.
3. The prevalence of submicroscopic malaria infections in the study area was 14.2%.
4. Topographic features of the local landscape and seasonality were identified as major correlates of submicroscopic malaria infection in the Lake Victoria area of western Kenya.
5. The study highlights the need for diagnostic tests that are more sensitive than blood smear microscopy to accurately detect submicroscopic infections and guide targeted interventions in areas with high transmission.

The implications of the study’s results for malaria control and prevention efforts in sub-Saharan Africa

1. Improved diagnostic methods: The study highlights the need for more sensitive diagnostic tests to accurately detect submicroscopic malaria infections. Implementing such tests in sub-Saharan Africa could help identify and target these hidden infections, leading to more effective malaria control and prevention efforts.

2. Targeted interventions: The identification of topographic features and seasonality as correlates of submicroscopic malaria infection suggests that targeted interventions can be implemented in specific areas and during specific times to reduce transmission. This could involve focusing vector control measures, such as insecticide-treated bed nets and indoor residual spraying, in areas with higher risk.

3. Integrated vector management: The study mentioned the evaluation of larviciding with Bti and community education and mobilization as supplementary interventions for malaria control. This highlights the importance of integrated vector management approaches that combine multiple strategies to target different stages of the mosquito life cycle and engage communities in malaria prevention efforts.

4. Regional context: While the study focused on western Kenya, the findings may have broader implications for sub-Saharan Africa. Understanding the factors influencing submicroscopic malaria infections and their impact on transmission can help inform malaria control and prevention strategies in other regions with similar ecological and epidemiological characteristics.

Introduction

The introduction of the paper discusses the current malaria control interventions in Kenya and the challenges faced in reducing malaria morbidity and transmission. It highlights the high vector densities in western Kenya and the presence of submicroscopic Plasmodium infections that are not detectable by standard diagnostic methods like blood smear microscopy. The introduction emphasizes the need for more sensitive diagnostic tests to accurately detect submicroscopic infections and guide targeted interventions. The study aims to investigate the correlates of submicroscopic malaria infection in the Lake Victoria area of western Kenya, particularly focusing on topographic features and seasonality. The introduction sets the context for the study and highlights the importance of understanding the factors influencing submicroscopic malaria infections for effective malaria control and elimination efforts.

Methods

The methods section of the paper describes the design and implementation of the study conducted in the Lake Victoria basin in Kisumu County, Kenya. The study utilized a cross-sectional community survey approach to assess malaria infection in three eco-epidemiologically distinct zones in Nyakach sub-County.

The surveys were conducted during both wet and dry seasons in 2019 and 2020. A total of 1,777 healthy volunteers participated in the study. Finger prick blood smears and dry blood spots on filter paper were collected from the participants for microscopic inspection and real-time PCR (RT-PCR) diagnosis of Plasmodium infection.

Participants who tested positive for Plasmodium infection through RT-PCR but had negative blood smears were considered to have submicroscopic infections. The prevalence of submicroscopic infections was correlated with topographical, demographic, and behavioral risk factors.

The data collected were analyzed using IBM SPSS Software Version 21.0. The Chi-square test was used to assess the significance of the association between malaria infection prevalence and seasons and topography. The Kruskal-Wallis test followed by Dunn’s multiple comparison test was used for multiple comparisons between Plasmodium species and seasonality.

Additionally, the agreement between microscopy and RT-PCR results was measured using Cohen’s kappa statistic, sensitivity, specificity, positive predicted value, negative predicted value, and diagnostic accuracy. Univariate binary logistic regression and multivariate mixed effect binary logistic regression analyses were employed to identify the risk factors associated with submicroscopic malaria infection.

Results

The study conducted cross-sectional community surveys during the wet and dry seasons in 2019 and 2020. A total of 458 and 388 participants were included in the wet season surveys, while 456 and 475 participants were included in the dry season surveys.

The prevalence of submicroscopic malaria infection varied across different topographic regions, with the lakeshore region having the highest prevalence. Gender, age, bed net usage, wall type, occupation, education level, household population size, bed net type, symptoms, and seasonality were among the variables investigated as potential risk factors.

In the univariate analysis, all risk factors were tested, and those with a p-value less than 0.50 were included in the multivariate analysis. In the multivariate analysis, variables with a p-value less than 0.05 were considered significant risk factors.

The results showed that topography, age, bed net usage, wall type, and seasonality were significant risk factors associated with submicroscopic malaria infection. The lakeshore region had a higher risk compared to the hillside and highland plateau regions. Older age groups, inconsistent bed net usage, mud wall type, and the wet season were also associated with increased risk.

The results provide insights into the risk factors associated with submicroscopic malaria infection in the study area, highlighting the importance of topography, age, bed net usage, wall type, and seasonality. These findings can inform targeted interventions and strategies for malaria control and prevention in the Lake Victoria basin in Kenya.

Discussion

The study found that despite the overall decrease in malaria burden in Kenya due to vector control interventions, malaria transmission remained high in the western regions bordering Lake Victoria. The high prevalence of submicroscopic malaria infections in the lakeshore region suggests the presence of a reservoir of infections that may contribute to ongoing transmission.

The results showed that topography, specifically living in the lakeshore region, was a significant risk factor for submicroscopic malaria infection. This finding is consistent with previous studies that have identified lakeshore areas as hotspots for malaria transmission due to favorable breeding conditions for malaria vectors.

Age was also identified as a significant risk factor, with school-aged children having a higher risk of submicroscopic infection. This finding aligns with the understanding that children are more susceptible to malaria due to their developing immune systems and increased exposure to mosquito bites.

Inconsistent bed net usage was associated with an increased risk of submicroscopic malaria infection. This highlights the importance of consistent and proper use of bed nets as a preventive measure against malaria.

The discussion also highlights the limitations of the study, such as the cross-sectional design, which limits the ability to establish causality. Additionally, the study focused on a specific geographic area, and the findings may not be generalizable to other regions.

The study emphasizes the need for more sensitive diagnostic tools, such as RT-PCR, to detect submicroscopic infections accurately. This is crucial for targeted interventions and surveillance efforts to identify and treat individuals with submicroscopic infections, who may serve as a reservoir for malaria transmission.

Conclusion

The study found that topography, age, bed net usage, wall type, and seasonality were significant risk factors associated with submicroscopic malaria infection. The lakeshore region had the highest prevalence of submicroscopic infections, highlighting the importance of targeted interventions in this area.

The study also emphasizes the need for more sensitive diagnostic tools, such as RT-PCR, to detect submicroscopic infections accurately. This is crucial for identifying and treating individuals with submicroscopic infections, who may serve as a reservoir for malaria transmission.

The findings of the study have important implications for malaria control and prevention efforts in the Lake Victoria basin in Kenya. The study highlights the importance of targeted interventions that consider the specific risk factors associated with submicroscopic malaria infection in the region.

My questions are

1. The study identified topography, specifically living in the lakeshore region, as a significant risk factor for submicroscopic malaria infection. What interventions or strategies could be implemented to specifically target and reduce malaria transmission in these high-risk areas?

2. The study found that inconsistent bed net usage was associated with an increased risk of submicroscopic malaria infection. What are some potential barriers or challenges to consistent bed net usage in other setting? How can these barriers be addressed to promote proper and consistent bed net usage as a preventive measure against malaria?

My answer to the discussion points are:
1)
1. Vector breeding sites: Mosquitoes that transmit malaria require suitable breeding sites, such as stagnant water bodies, for their larvae to develop. During the dry season, there may be fewer breeding sites available due to reduced rainfall and water scarcity. However, the remaining breeding sites could become more concentrated and productive, leading to higher mosquito populations and increased malaria transmission.

2. Human behavior and exposure: During the dry season, people may engage in activities that increase their exposure to mosquito bites. For example, water scarcity may lead to increased reliance on alternative water sources, such as open containers or uncovered wells, which can serve as breeding sites for mosquitoes. Additionally, agricultural activities or outdoor work may be more common during the dry season, increasing the chances of mosquito bites and subsequent malaria transmission.

3. Vector behavior and survival: Mosquito behavior and survival can be influenced by environmental conditions. In some cases, mosquitoes may adapt their behavior during the dry season to seek out alternative sources of water or blood meals, potentially increasing their contact with humans and the transmission of malaria.

2)
1. Longitudinal studies: The current study utilized a cross-sectional design, which limits the ability to establish causality or determine the temporal relationship between risk factors and submicroscopic malaria infection . Future research could utilize a longitudinal design to follow individuals over time and better understand the dynamics of malaria transmission and the impact of risk factors on infection outcomes.

2. Intervention studies: The current study focused on identifying risk factors for submicroscopic malaria infection, but did not evaluate the effectiveness of specific interventions to prevent or control malaria transmission. Future research could evaluate the impact of interventions such as insecticide-treated bed nets, indoor residual spraying, or larviciding on malaria transmission and submicroscopic infection outcomes.

3. Molecular epidemiology: The current study utilized PCR-based methods to detect submicroscopic malaria infection, but did not analyze the genetic diversity or distribution of malaria parasites in the study population. Molecular epidemiology approaches could provide insights into the transmission dynamics and genetic diversity of malaria parasites in the study area, which could inform targeted control strategies.

4. Health system factors: The current study focused on individual-level risk factors for submicroscopic malaria infection, but did not evaluate the impact of health system factors on malaria control and prevention. Future research could explore the role of health system factors such as access to diagnostic testing, treatment, and surveillance in reducing the burden of malaria in the study area.

I was late for the class and missed the first part of seminar.🙏 The selected paper was interesting and gave the idea of factor investigation.
For topic 1, I think some human behavior and general routine could potentially increase the risk of exposure to mosquitos and differentiate the infection rate among each factor. For example, male might have occupations which involve travel outdoor with more risk to be bitten compared to women. Population in Lakeshores area undertook fishing as their main activity which expanded the time spent near to the water and caused higher infection rate.
Moreover, economic status would allow the ability to protect themself from the mosquito. Therefore, the area with poor quality of housing and lower economic status(Lakeshores area was mentioned in research paper) might have less ability of self protection resulting in higher infection rate.
The same behavior and economic status which occurred with people under the same characteristics and demographics potentially differentiated the infection rate.

For topic 2, I looked at figure 1 comparing the prevalence in Dry season 2019 and 2020. Even though the seasons matched, the infection rates weren’t similar. Therefore, apart from the climate and level of natural water, there might be other factors related to the high infected rate in dry season 2019. Environment and behavior might be the cause of high rate such as people gathering more in dry season, the consistency of self protection methods which possibly weren’t strengthened enough and personal reserve ponds during dry season.

Hi Siriphak. Same to Boonyarat, I was joining this forum when it was almost finished. My apologize. But I catched up some points in this paper.

While most kinds of the literature suggest that submicroscopic malaria (defined as low-density Plasmodium) is detected in the migrant population through travel activities from an endemic area, this research revealed that residing in the lakeshore contributes to vulnerability the most. I preferably argue that the male factor supports the continuity of SMM chain transmission as they have much more opportunities to go outside in the afternoon and back home at night while the home is around the lakeshore. To address the 2nd discussion, my opinion is human behavior. People tend to have much more activities in the dry season which shares a significant impact on the prevalence of Malaria.