Serological diagnosis of dengue in laboratory practice in Kolkata

PURPOSE

To find out the most suitable serological investigative procedures to diagnose dengue cases effectively in the laboratory practice identifying primary and secondary cases as well as period of suffering.

MATERIALS AND METHODS

Dengue suspected cases sent to the laboratory in 2012 in central Kolkata by the local physicians were categorised into seven panels according to the investigations asked for such as (1) only dengue-specific NS1 antigen (2) only IgM antibodies, (3) NS1+IgM+IgG antibodies, (4) only IgM and IgG, (5) NS1+IgM, (6) NS1+IgG and (7) only IgG.

RESULTS

Out of 1892 suspected cases, dengue was diagnosed in 725 (38.3%). Through panels I, II, III, IV, V, VI and VII, it was possible to diagnose dengue in (I) 35.98% (435/1209), (II) 37.5% (24/60), (III) 49% (173/354), (IV) 30.8% (68/221), (V) 60.5% (23/38), (VI) 40% (2/5) and (VII) 0 of cases respectively. Detail information such as confirmed diagnosis, duration of the disease (whether early or prolonged) and classification of primary and secondary dengue in such early or prolonged stages would only be possible in panel III, which information would be helpful for effective monitoring and treatment of dengue patients. In all other panels, merely fragmentary information would be obtained.

CONCLUSIONS

Serodiagnostic tests dengue-specific NS1 antigen and IgM and IgG antibodies when conducted simultaneously would be able to diagnose confirmed dengue cases categorising primary and secondary dengue along with the duration of the disease, whether early or prolonged.

Chikungunya in west bengal, India

Fever of unknown origin broke out in several districts of West Bengal, from August 2007 to December 2007. The cases were suffering from high fever, severe joint pain lasting for several weeks after clinical cure and appearance of skin rashes. Patients' sera were collected at least five days after fever and were analyzed to detect specific IgM antibodies. A total of 800 patients were investigated and 321 (40.13%) were found to be reactive for Chikungunya antibodies. Of the patients, 66% were male. Predominant signs and symptoms observed in the sero-positive cases were fever (100%), arthralgia (96%) and diffuse erythematous skin rash (94%). Of the patients, 3% had haemorrhagic manifestations. Re-emerging Chikungunya virus spread in epidemic form in several districts of West Bengal after a gap of four decades.

Castlemans disease in HIV infected patient from eastern India

Castlemans disease is a rare lymphoproliferative disorder. We report a patient of Castlemans disease with advanced HIV infection who responded well to conventional HAART. This case is interesting because of the rarity of the disease in the eastern part of India and its good out come with antiretroviral therapy.

Differential decline in Leishmania membrane antigen-specific immunoglobulin G (IgG), IgM, IgE, and IgG subclass antibodies in Indian kala-azar patients after chemotherapy

Pathogenesis in kala-azar is associated with depressed cellular immunity and significant elevation of antileishmanial antibodies. Since these antibodies are present even after cure, analysis of the parasite-specific isotypes and immunoglobulin G (IgG) subclasses in kala-azar patients may shed new light on the immune responses during progression and resolution of infection. Using leishmanial membrane antigenic extracts, we investigated the relative levels of specific IgG, IgM, IgA, IgE, and IgG subclasses in Indian kala-azar patient sera during disease, drug resistance, and cure. Acute-phase sera showed strong stimulation of IgG, followed by IgE and IgM and lastly by IgA antibodies. IgG subclass analysis revealed expression of all of the subclasses, with a predominance of IgG1 during disease. Following sodium stibogluconate (SAG) resistance, the levels of IgG, IgM, IgE, and IgG4 remained constant, while there was a decrease in the titers of IgG2 and IgG3. In contrast, a significant (2.2-fold) increase in IgG1 was observed in these individuals. Cure, in both SAG-responsive and unresponsive patients, correlated with a decline in the levels of IgG, IgM, IgE, and all of the IgG subclasses. The stimulation of IgG1 and the persistence, most importantly, of IgE and IgG4 following drug resistance, along with a decline in IgE, IgG4, and IgG1 with cure, demonstrate the potential of these isotypes as possible markers for monitoring effective treatment in kala-azar.

Histoplasmosis in eastern India: the tip of the iceberg?

Systemic histoplasmosis has various clinical presentations and is of especially concern in immunocompromised patients. A high index of suspicion is required for its diagnosis. A total of 38 cases had been reported from India up to 1996. The most frequent occurrence of cases was around Calcutta in eastern India where the previous case was detected 20 years earlier. However, we have diagnosed 5 cases in the past 2 years from eastern India which are reported here. These cases may indicate under-diagnosis and under-reporting of histoplasmosis in India. All 5 patients had disseminated disease with multisystem involvement including 2 with bilateral adrenal enlargement. Two were diabetic and only 1 patient was infected with HIV.

Immunoglobulin subclass distribution and diagnostic value of Leishmania donovani antigen-specific immunoglobulin G3 in Indian kala-azar patients

Visceral leishmaniasis, or kala-azar, a fatal tropical disease, remains problematic, as early diagnosis is difficult and treatment often results in drug resistance and relapse. We have developed a sensitive enzyme-linked immunosorbent assay (ELISA), using leishmanial membrane antigenic extracts (LAg) to detect specific antibody responses in 25 untreated Indian visceral leishmaniasis patients. To investigate the pathogenetic significance of isotype markers in kala-azar, relative levels of specific immunoglobulin G (IgG), IgM, IgA, IgE, and IgG subclasses were analyzed under clinically established diseased conditions. Since LAg showed higher sensitivity for specific IgG than lysate, the immunoglobulin isotype responses were evaluated, with LAg as antigen. Compared to 60 controls, which included patients with malaria, tuberculosis, leprosy, and typhoid and healthy subjects, visceral leishmaniasis patients showed significantly higher IgG (100% sensitivity, 85% specificity), IgM (48% sensitivity, 100% specificity), and IgE (44% sensitivity, 98.3% specificity) responses. Low levels of IgA in visceral leishmaniasis patients contrasted with a 13-fold-higher reactivity in sera from patients with leprosy. Among IgG subclasses, IgG1, -3, and -4 responses were significantly higher in visceral leishmaniasis patients than in the controls. IgG2 response, however, was significantly higher (twofold) in leprosy than even visceral leishmaniasis patients. The rank orders for sensitivity (IgG = IgG1 = IgG3 = IgG4 > IgG2 > IgM > IgE > IgA) and specificity (IgM = IgG3 > IgE > IgG4 > IgG2 > IgG > IgG1 > IgA) for LAg-specific antibody responses suggest the potentiality of IgG3 as a diagnostic marker for visceral leishmaniasis.

Distribution of IgG subclasses in antimonial unresponsive Indian kala-azar patients

Sodium antimony gluconate (SAG) is the mainstay of treatment for visceral leishmaniasis (VL) or kala-azar. In view of the increasing incidence of refractoriness to SAG in India, we compared the levels of parasite-specific IgG and IgG subclasses in 20 longitudinally followed up kala-azar patients. In both SAG-responsive (n = 10) and unresponsive patients (n = 10), the levels of total IgG, IgG1, IgG2, IgG3 and IgG4 were increased, the rank order being IgG1 > IgG2 > IgG3 = IgG4. Following treatment, a significant decrease in total IgG and the four subclasses occurred in the SAG-responsive group, whereas in the SAG-unresponsive group these levels were unchanged or slightly increased. Therefore, monitoring of IgG1 and IgG2 levels in Indian kala-azar patients is a good serologic alternative to monitoring the disease status.