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Year : 2016  |  Volume : 34  |  Issue : 1  |  Page : 82--84

A study on gender-related differences in laboratory characteristics of dengue fever

A Chakravarti, P Roy, S Malik, O Siddiqui, P Thakur 
 Department of Microbiology, Maulana Azad Medical College, New Delhi, India

Correspondence Address:
A Chakravarti
Department of Microbiology, Maulana Azad Medical College, New Delhi
India

Abstract

Studies have reported significant gender-related differences in serological tests for detection of NS1 antigen and IgM antibody used for diagnosing dengue fever. However, no such study has been undertaken in India though dengue fever is endemic in this country. Therefore, this study was planned to study the association of serological findings with gender in 700 patients suspected to be suffering from dengue fever in the Indian setting. Haematological parameters of seropositive patients were also studied. Seropositivity and haemorrhagic findings were significantly associated with the female gender. Positive NS1 antigen and IgM antibody results were significantly associated with females and males, respectively.

How to cite this article:
Chakravarti A, Roy P, Malik S, Siddiqui O, Thakur P. A study on gender-related differences in laboratory characteristics of dengue fever.Indian J Med Microbiol 2016;34:82-84

How to cite this URL:
Chakravarti A, Roy P, Malik S, Siddiqui O, Thakur P. A study on gender-related differences in laboratory characteristics of dengue fever. Indian J Med Microbiol [serial online] 2016 [cited 2020 Jan 18 ];34:82-84
Available from: http://www.ijmm.org/text.asp?2016/34/1/82/174106

Full Text

 Introduction



Dengue fever is a major public health problem in India.[1],[2] Few studies across the world have reported significant gender-related differences in the serological tests for dengue fever involving detection of NS1 antigen and IgM antibody.[3],[4] However, data regarding this aspect of dengue fever are lacking in the Indian setting though dengue fever is a major arboviral disease in the subcontinent.[1] It is of utmost importance to document the gender-related serological features of dengue fever as it would aid in formulating management guidelines. Hence, this study was planned to study the association of the serological and haematological findings with gender in patients suspected to be suffering from dengue fever.

 Materials and Methods



This was a retrospective study and was conducted at the Dengue Sero-surveillance Laboratory of a 2000-bedded Tertiary Care Government Hospital in Delhi. Ethical approval certificate for the study was obtained from the Institutional Ethical Committee. Seven hundred patients from 7 months to 73 years of age suspected to be suffering from dengue fever and presenting to the hospital during dengue outbreak 2013 (July 2013 to December 2013) were included in this study. The mean age for both males and females was 27 years. Suspected cases of dengue were defined as individuals who presented with symptoms of dengue fever and any warning sign.[1] The latter symptoms of suspected cases included the following: Persistent vomiting, mucosal bleeding, lethargy, agitation, decrease in platelet count, weak and rapid pulse, and hypotension.[1] All the patients are presented between the 5th and 9th day after onset of illness. The mean day of presentation was a 7th day for both males and females.

Serum samples of these patients were tested for dengue NS1 antigen using dengue NS1 antigen capture ELISA (PanBio Diagnostics, Brisbane, Australia) and dengue IgM antibody by DEN IgM capture ELISA (National Institute of Virology, Pune, India) kits, respectively. Haematological parameters (leucocyte count, haemoglobin, and platelet count) of seropositive patients were noted and correlated with results of diagnostic markers and gender. Leucopenia was defined as a leucocyte count of <5000/µL, thrombocytopenia was defined as a platelet count of <100,000/µL, and anaemia was defined as haemoglobin >11 g/dL.[1],[5]

For statistical analysis, GraphPad Inc., statistical software (2236 Avenida de la Playa La Jolla, CA 92037, USA) was used for calculation of P value using Fisher's exact test. Statistical significance was defined as P < 0.05.

 Results



Of the 700 samples tested, 280 (40%) were positive for either dengue antigen or antibody, but none of the samples was positive for both antigen and antibody. Among the dengue seropositive cases, the proportion of females was higher giving male to female ratio (M:F) of 1:1.1 [Table 1]. Dengue seropositivity was significantly associated (P < 0.0001) with the female gender [Table 1]. Thrombocytopenia, leucopenia, and anaemia were also significantly associated with females as compared to males (P < 0.0001) [Table 1]. NS1 antigen positivity was significantly associated with females (P < 0.0001), while IgM antibody positivity was significantly associated with males (P < 0.0001) [Table 1].{Table 1}

 Discussion



In the present study, 40% of the suspected cases were found serologically positive for dengue infection. The remaining 60% serologically negative suspected dengue patients may be suffering from other illnesses which share clinical manifestations with dengue fever such as chikungunya, influenza, measles, rubella, infectious mononucleosis, and meningococcal infection.[6] Dengue seropositivity was found to be significantly associated with the female gender. Studies in South America generally report that both sexes are equally affected although a male to female ratio of 0.65:1 has been described as “typical” for dengue.[7] However, contrasting results have also been reported in some cases. Three independent studies from epidemics in India done by Agarwal et al., Ray et al., and Wali et al., found nearly twice the number of male patients infected with dengue compared to females, M:F being 1.9:1, 1:0.57, and 2.5:1, respectively.[7],[8],[9],[10] These studies were hospital-based and may represent those who sought care rather than the actual infected population.[7],[10] It is widely recognised that in many Asian communities, lower disease incidence in women may be a statistical artefact related to lower reporting for women from traditional practitioners not reporting to public surveillance systems.[7]

The laboratory findings indicative of haemorrhagic and severe dengue fever that is, thrombocytopenia, leucopenia, and anaemia were significantly associated with females as compared to males. Similar results have been obtained in various other studies.[7],[11],[12] Of importance are two studies in Asia by Kabra et al. and Shekhar and Huat, where the severe illness was consistently higher among females though incidence was higher in males.[7],[11],[12] It has been suggested that immune responses in females are more competent than in males, resulting in greater production of cytokines, and also the capillary bed of females is prone to increased permeability which leads to severe manifestations of dengue in females but milder forms in males.[7] In addition, in many of the Asian communities, women are less likely to be taken for care at a hospital when ill or are taken at late stages of the disease when no other options are available.[7]

In the present study, NS1 antigen positivity was significantly associated with females while IgM antibody positivity was significantly associated with males. Similar and contrasting results have been obtained in various studies across the world. Brown et al. has found a statistically significant association between the presence of IgM antibodies and male gender,[4] while Ali et al. reported no significant statistical association between IgM antibody positivity and male gender.[13] In a study by Kosasih et al., a significantly higher sensitivity of NS1 antigen was seen in females than in males.[3] However, to the best of our knowledge, this is the first study from India reporting an association between serological tests for dengue fever and gender. The association between NS1 antigen and higher sensitivity in females may be related to a more severe manifestation of the infection in the female gender. NS1 antigen is a protein encoded by the virus. In infected cells in vitro, NS1 is detected intracellularly, on the surface and secreted in copious amounts into the medium. NS1 elicits a humoral and cellular immune response in humans. Recent findings have shown that NS1 antigen positivity is correlated with higher viremia or antigenemia, which is usually found in more severe cases. Haemorrhagic features seen in severe dengue fever occur due to the cross-reactivity of anti-dengue NS1 antibodies with platelets and endothelial cells. NS1 antigen also plays a pivotal role in the occurrence of vascular leakage through complement and cytokine responses.[3]

 Conclusions



The findings of this study have major implications from diagnosis and management point of view of dengue fever. A higher index of suspicion of severe dengue fever must be maintained for the female gender. To expedite the serological diagnosis of dengue fever, we recommend using tests for NS1 antigen and IgM antibodies as the preferred diagnostic tests in females and males, respectively.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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