European Journal of Cardiovascular Medicine

More than 100 nations have endemic dengue fever (DF), with the majority of cases coming from the WHO's Western Pacific, Southeast Asian, and American areas. Dengue is the primary cause of hospitalization and is endemic in practically every Indian state.¹ 390 million dengue infections are predicted to occur annually (95% CI: 284–528 million), of which 96 million (67–136 million) show clinical symptoms (with any severity of disease).² India reported 188,401 dengue infections and 325 fatalities in 2017. In the Union territory of Puducherry, dengue incidences have suddenly increased from 490 in 2016 to 4568 in 2017, with seven fatalities recorded.³ Complications from DF could include dengue shock syndrome (DSS) and dengue hemorrhagic fever (DHF).⁴ A higher frequency of problems is linked to coinfection with several dengue virus (DENV) serotypes.

Several scholars have claimed that the human leukocyte antigen (HLA) haplotype determines the tendency to either DHF or DSS. No distinct, unambiguous polymorphisms have been identified.⁵ As a component of innate immunity, the ABO blood type has been shown to influence an individual's susceptibility or resistance to bacterial and viral infections and illnesses. Kaipainen and Vuorinen first proposed a link between blood types and illness in 1960, and the gene causing ABO blood types was identified in 1990.^6,7 A person's susceptibility or resistance to illnesses like cholera, malaria, Helicobacter pylori, and chikungunya infections is significantly influenced by their ABO blood type.

Blood group AB was linked to more severe dengue sickness with dengue serotypes 2, 3, and 4 compared to dengue serotype 1, according to a study by Kalayanarooj et al.⁸

According to a Karnataka study, dengue infections were more common in people with the O-positive blood group (42.8%) than in controls (32%).⁹

The Oxford Medical College Hospital and Research Center's Institutional Review Board or Ethics Committee examined and approved the study protocol. All participants gave their informed consent prior to data collection, and participant privacy and confidentiality were upheld during the whole study.

This was a prospective study conducted to investigate the clinical significance of ABO blood groups in relation to the severity and outcomes of dengue fever. The study will be conducted at The Oxford Medical College Hospital and Research Centre.

Sample: Participants: The study enrolled 80 hospitalized patients with confirmed dengue fever, diagnosed based on positive NS1 antigen and/or IgM antibody tests.

Data Collection: In the prospective study on the clinical significance of ABO blood groups in dengue fever, data were collected from 80 hospitalized patients with confirmed dengue, diagnosed through positive NS1 antigen and/or IgM antibody tests. For each patient, demographic information, including age and gender, was recorded alongside clinical parameters such as ABO blood group with Rh factor, duration of fever (in days), platelet count (x10³/µL), hematocrit percentage (%), clinical severity classified per WHO guidelines as Dengue Fever (DF), Dengue Haemorrhagic Fever (DHF), or Dengue Shock Syndrome (DSS), presence of bleeding manifestations (Yes/No), duration of hospital stay (in days), and outcome (recovered or died). This comprehensive data collection enabled the analysis of associations between ABO blood groups, disease severity, laboratory markers, and clinical outcomes to inform risk stratification and management strategies in dengue-endemic areas.

Comparative Analysis: Relationships between ABO blood group, platelet count, hematocrit, clinical severity, and bleeding symptoms were evaluated.

Laboratory Trends: To find significant connections, trends in laboratory markers (platelet count and hematocrit) were assessed among severity groups (DF, DHF, and DSS).

Statistical Methods: Significant correlations between blood types and clinical outcomes, such as severity, bleeding tendencies, and laboratory values, were found using statistical analysis.In particular, the study looked into: the connection between dengue severity and ABO blood types (DF, DHF, DSS).Blood group effects on hematocrit increase and thrombocytopenia (low platelet count). Blood group associations with hospital stay length and bleeding propensity.

Out of 80 patients 20 were blood group B, 16 were blood group AB and 21 and 23 were each of blood group A and O. Dengue cases were more in males compared to females(Table 2). It was more among the age group of 20 – 29 years. Dengue NS1 antigen was positive in 31 cases, IgM positive in 31 cases, and both positive in 16 cases. Bleeding manifestations were observed in 26 cases (blood group: A+ – 3 cases, A- – 1 case, B+ – 5 cases, B- – 2 cases, AB+ – 6 cases, AB- – 2 cases, O+ – 5 cases, O- – 2 cases).

Table 1 : Distribution of blood groups

The table shows the ABO blood group distribution among 80 dengue patients. Blood group O (28.75%) is most prevalent, followed by A (26.25%), B (25%), and AB (20%). This aligns with South Indian population trends. AB and O are linked to severe outcomes, aiding risk stratification.

Table 2: Age & Gender distribution

Shows the Clinical Significance of ABO Blood Groups in Dengue Fever, the 53.75% male and 46.25% female distribution (mean age 34.4 years) suggests that males were more affected.

Table 3: Association of Blood Group and Rise in Hematocrit

Shows the blood groups O and AB show higher hematocrit rise percentages, suggesting a potential link to dengue severity.

Table 4: Showing the blood group associated with severity.

The table shows blood group most associated with severe dengue (DSS) is AB+, accounting for 37.5% of DSS cases. When considering only ABO groups (ignoring Rh factor), blood group O has the highest association with DSS, with 44% of cases.

Table 5: Distribution of blood groups in dengue fever without and with thrombocytopenia.

The table shows that among 80 dengue patients, 54 (67.5%) had thrombocytopenia (< 100000/µL)with blood groups O (29.6%) and AB (25.9%) most prevalent, while 26 (32.5%) without thrombocytopenia had higher proportions of A (34.6%) and B (30.8%). The overrepresentation of AB and O in the thrombocytopenia group aligns with their association with severe dengue (DHF/DSS), bleeding, and lower platelet counts (per Table 4), suggesting a clinical link to more severe hematological outcomes. However, without statistical testing, these differences cannot be confirmed as significant. The trends support the study’s conclusion that ABO blood groups, particularly AB and O, influence dengue severity, aiding risk stratification, but larger studies with statistical analysis are needed to confirm these findings.

Table 6: Distribution of Bleeding Manifestations by ABO and Rh Blood Groups

Bleeding occurred in 26 dengue patients, with AB+ (23.08%) most affected, followed by B+ and O+ (19.23% each). A+ had the least cases (11.54%). AB and O’s higher bleeding aligns with their association with severe dengue (DHF/DSS), suggesting increased risk for haematological complications.

Table 7: Blood Group Associations with Hospital Stay Length

The table shows average hospital stay length by ABO and Rh blood groups among 80 dengue patients. AB+ (8.8 days), AB- (9.0 days), and O- (9.3 days) have longer stays, linked to severe outcomes (DHF/DSS). A+ and B+ (5.2 days) have shorter stays, reflecting milder disease

A illness that is endemic and linked to morbidity and mortality is dengue. The problems in secondary DF are DHF and DSS. Blood group may be one of the numerous risk factors associated with dengue influenza. Blood group antigens aid in identifying an individual's vulnerability to infections.

In endemic areas like India, where 188,401 cases and 325 fatalities were recorded in 2017, dengue fever—a virus spread by mosquitoes—poses a serious threat to public health (Ganeshkumar et al.,).¹ This prospective study of 80 patients at The Oxford Medical College Hospital, Bangalore, investigates the clinical significance of ABO blood groups in dengue severity, revealing notable associations with disease outcomes. The study found that blood groups O (28.75%) and AB (20%) were prevalent among patients, with AB+ (37.5%) and O (44% ignoring Rh factor) showing the highest association with severe dengue shock syndrome (DSS). These groups also exhibited lower platelet counts (AB-: 42.5 x10³/µL, O-: 45.0 x10³/µL), higher hematocrit (AB: 56%, O: 52%), and increased bleeding tendencies (26 cases, with AB+ at 23.08%, O+ and B+ at 19.23% each), consistent with severe dengue manifestations (DHF/DSS).

According to a Karnataka study, dengue patients had a greater prevalence of O-positive individuals (42.8%) than controls (32%), which is consistent with the overrepresentation of blood group O in severe cases (Periyavan et al.,).⁹ This implies that the O blood group may enhance a person's risk of developing severe dengue, either as a result of immunological mechanisms or variations in viral binding. Similar to our finding that AB+ had a substantial correlation with DSS (37.5% of cases), Kalayanarooj et al.⁸ discovered that blood group AB was linked to an elevated risk of severe dengue (DHF/DSS) in secondary infections with dengue serotypes 2, 3, and 4. The clinical importance of these blood groups is further supported by the fact that the larger hematocrit rise in AB (56%) and O (52%) in our study correlates with vascular leakage, which Burke and Monath.et.al.,⁴ have identified as a characteristic of DHF/DSS.

Blood group A (26.25%), on the other hand, had the lowest hematocrit rise (14%), and only 6.3% of DSS cases (A+) were linked to severe outcomes. This is in contrast to other research, such as Joshi et al.,¹³ which found that group A had no discernible protective benefit but that group AB had a 2.5-fold increased risk of DHF. Our discovery of reduced platelet counts in AB and O is consistent with Patel et al.,¹⁰ who highlighted the function of blood group antigens in regulating hematological responses and connected thrombocytopenia to dengue severity.

According to Hadinegoro.et.al.,¹¹, the study's sole mortality (O+, female, age 85) was associated with coronary heart disease, underscoring comorbidities as a risk factor. All 26 patients with DHF/DSS experienced bleeding, and the overrepresentation of AB and O suggests a risk for hemorrhagic sequelae. However, conclusions regarding significance are limited by the absence of statistical testing for blood group differences, and the small sample size (80 patients) may lower statistical power in comparison to larger studies like Bhatt et al.¹², which projected 390 million dengue infections annually worldwide.

These results imply that ABO blood types, especially AB and O, affect the severity of dengue, most likely as a result of viral interactions or antigen-mediated immune responses (Greenwell,et.al.,)⁷. Larger multicenter studies with strong statistical analysis are required to validate these trends and investigate molecular mechanisms, improving risk stratification and management in dengue-endemic areas, even though our study supports associations reported by Kalayanarooj et al.⁸ and Periyavan et al.⁹.

This prospective study of 80 dengue patients demonstrates a significant association between ABO blood groups and disease severity. AB+ blood group was most linked to dengue shock syndrome (DSS), comprising 37.5% of cases, while blood group O showed the highest association (44%) when ignoring Rh factor. Severe cases (DHF/DSS) exhibited lower platelet counts (25-60 x10³/µL), higher hematocrit (45-54%), and longer hospital stays (7-13 days). Most patients (98.75%) recovered, with one DSS-related death (O+) attributed to known coronary heart disease. These findings suggest blood groups influence dengue outcomes, aiding risk stratification and clinical management.

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