Rapid spread of chikungunya virus infection in Orissa: India.

BACKGROUND & OBJECTIVES: A large number of cases of undiagnosed fever and joint pain were reported from different parts of the State of Orissa since February 2006. Epidemiological and laboratory investigation were carried out to confirm the cause of emerging illness, which was provisionally suspected as Chikungunya (CHIK) fever. METHODS: Upon getting the reports of suspected CHIK like illness in different parts of the State, epidemic investigations were carried out in the outbreak affected villages. Case history was recorded, clinical examination undertaken and blood samples collected for seroconfirmation for CHIK IgM antibody using ELISA based kit. Simultaneously vector survey was also carried out. RESULTS: With no previous record of CHIK infection in the State, the first outbreak was confirmed during February 2006. Subsequently, the infection spread to 13 of 30 districts in different episodes covering 79 villages till November 2007. Attack rate was 9-43 per cent in the different outbreaks with average seropositivity of 24 per cent to CHIK specific IgM. Morbidity was high though no deaths were recorded. Aedes aegypti and Ae. albopictus were identified as the possible vectors for transmission. INTERPRETATION & CONCLUSIONS: The report confirmed emergence of CHIK infection in the State of Orissa, India, and its spread to a larger geographic zone in a short period which warrants public health measures to control further spread.

Transplacental transfer of filarial antigens from Wuchereria bancrofti-infected mothers to their offspring.

OBJECTIVE: Maternal infection has been considered to be a risk factor for filarial infection in offspring. In order to examine the influence of maternal infection in neonates, we have determined the prevalence of circulating filarial antigen (CFA) and anti-filarial antibodies in 119 maternal and corresponding cord blood samples collected from an area endemic for bancroftian filariasis. METHOD: Prevalence of antigenaemia was detected using Og4C3 circulating filarial antigen enzyme-linked immunosorbent assay. The presence of microfilariae was determined by filtration of a 1 ml sample through a Nuclepore membrane. Antibody isotypes (IgG, IgM, and IgE) to filarial antigen (Setaria digitata antigenic extract) were determined by enzyme linked immunosorbent assay (ELISA). RESULTS: Microfilariae were detected in 14 cases (11.8%), whereas the Og4C3 assay could detect filarial antigen in 44.5% of pregnant mothers. Interestingly, 24.5% of samples born from CFA-positive mothers were found positive for CFA. None of the cord samples from CFA-negative mothers were found positive for CFA. No significant difference was observed in prevalence of filarial-specific IgG, IgM and IgE antibodies in CFA-positive and negative mothers. IgG antibody was detected in 60.5% of maternal and 21.8% of cord samples. IgG antibody in the cord does not differ with the antigen status of the mother. In contrast IgM and IgE antibody prevalence was significantly higher in cord from infected mothers than non-infected mothers (11.3% vs 0 for IgM, 24.5% vs 3.03% for IgE). CONCLUSION: Our study demonstrates the transplacental transfer of circulating filarial antigen from mother to cord. Filaria-specific IgM and IgE antibodies were higher in cord blood from infected mothers than from non-infected mothers. The findings of the study provide additional circumstantial evidence for pre-natal sensitization to filarial antigens developed in utero.

Protective efficacy of a filarial surface antigen in experimental filariasis.

A water-insoluble, detergent-soluble, surface-associated glycoprotein, designated as Dssd1, was found to induce microfilaria clearance in Mastomys coucha implanted with Setaria digitata. Intraperitoneal implantation of adult female worms of S. digitata in M. coucha could induce microfilaraemia lasting about 165 days in circulation. Immunization of M. coucha with Dssd1 antigen either before or after implantation of worms resulted in a significant reduction in microfilaria density. Complete clearance of circulating microfilaria was achieved by immunization (before and after implantation) in animals by 95 and 105 days post-implantation, respectively, indicating the efficacy of Dssd1 antigen in the clearance of microfilaraemia in infected M. coucha.

Antigenemia in young children living in Wuchereria bancrofti-endemic areas of Orissa, India.

The prevalence of filarial antigenemia (an indicator of adult worm burden) among 610 children, aged 3-15 years, was determined in three endemic villages of Khurda District, Orissa, India, during 2005. Prevalence of antigenemia, detected using Og4C3 circulating filarial antigen ELISA, was 32.6% compared with 10% microfilaraemia. Although the prevalence of antigenemia increased marginally with increase in age, no significant difference was observed among the children of different age groups (28.3% in 3-5 years, 31.5% in 6-10 years and 35.2% in 11-15 years), indicating that the adult worm burdens did not vary much according to the age of the study children. Gender did not influence the prevalence of antigenemia. The study emphasizes the advantage of using the circulating filarial antigen assay for detecting true filarial infection and demonstrates a high prevalence of antigenemia among the 610 children studied.

Parasite antigenaemia and IgG4 antibodies to a filarial protease in an endemic human population in India.

Levels of circulating filarial antigen (Og4C3) and IgG4 antibodies to a filarial protease were determined in subjects of Wuchereria bancrofti exposed sera from Orissa, India. In addition to all individuals with antigenaemia (microfilaraemia), IgG4 antibodies were also detected in some individuals without antigenaemia. A 2-year longitudinal follow-up indicated that IgG4 seropositivity in asymptomatic amicrofilaraemics could be a risk factor for acquiring infection (antigenaemia).

Antigenemia is associated with low antibody response to carbohydrate determinants of a filarial surface antigen.

The IgG response to a filarial surface antigen (DssdI) was evaluated in circulating antigen (Og4C3 test) positive and negative individuals from the Wuchereria bancrofti endemic region of Orissa, India. Circulating filarial antigen (CFA) positive individuals exhibited depressed antibody levels to DssdI and individuals with high antibody levels were invariably CFA negative. Low IgG levels to DssdI are associated with CFA positivity irrespective of microfilaraemia and clinical status. Thus asymptomatic microfilaraemic individuals with antigen positivity exhibited low IgG levels similar to symptomatic (chronic filariasis with elephantiasis, hydrocele) or asymptomatic amicrofilaraemic individuals with antigenemia. Western blot analysis revealed a band of approximately 210 kDa reactive with CFA-negative, but not with CFA-positive sera. DssdI was subjected to mild periodate oxidation to investigate the role of carbohydrate epitopes. The treatment considerably reduced the antigenic recognition of DssdI, stressing the immunodominance of carbohydrate residues of DssdI in infection-free individuals. In contrast, individuals with active infection failed to produce such antibodies to filarial surface carbohydrates.

Age-dependent prevalence of asymptomatic amicrofilaraemic individuals in a Wuchereria bancrofti-endemic region of India.

The age-related prevalence of asymptomatic amicrofilaraemics, apparently uninfected individuals, was determined in a Wuchereria bancrofti-endemic region of Orissa, India during 2001. The prevalence of these uninfected individuals was highest in the younger age groups (aged < or = 15 years), decreased rapidly in those aged > 15 to 40 years, and then stabilized in those aged > 40 years.

Antigenemia at 10 years after diethylcarbamazine treatment of asymptomatic microfilaraemic individuals: marginal conversion to infection-free state.

A group of asymptomatic microfilaraemic individuals (n = 44, 29 males, 15 females) living in a Wuchereria bancrofti endemic region of Orissa, India, was treated with a standard regimen of diethylcarbamazine (12 days, 6 mg/kg) in 1990. The incidence of microfilaraemia and antigenemia (Og4C3) was determined after a gap of 10 years in 2000. Nineteen individuals reacquired microfilariae (43.2%, 11 males, eight females), five males developed hydrocele, two females became acute filarial patients and 18 subjects (13 males, five females) were asymptomatic amicrofilaraemics. Filarial antigen was detected in 36 individuals (81.2%, 27 male, nine female) comprising microfilaraemics, amicrofilaraemics and diseased. Only eight individuals (18.2%, two males, six females) remained antigen free.

A long-term follow-up of asymptomatic amicrofilaraemic individuals living in a filaria-endemic region of Orissa, India: infection and disease status.

A group of asymptomatic amicrofilaraemic individuals (endemic normals) aged > 12 years was identified in 2 filaria-endemic villages of Orissa, India in 1990 (Bajapur village, n = 40) and in 1994 (Olosingh village, n = 47). They were re-examined for microfilaraemia and disease status in the year 2000 after a 10-year and a 6-year period. Studies conducted at both villages yielded a similar pattern in the development of disease. Above 85% of the females remained normal, compared to 54% of males. Remaining individuals had acquired hydrocoele (males) and adenolymphangitis (both males and females). Only 1 individual converted to having asymptomatic microfilariae. No case of elephantiasis was observed. Results indicate that most females remained normal and males faced considerable risk of developing hydrocoele in these Wuchereria bancrofti-endemic areas.

Immunological profile of treated lepromatous leprosy patients.

The immune responses of 19 treated lepromatous patients who had remained smear negative for a long period were assessed for specific cell-mediated immunity (CMI), anti-Mycobacterium leprae antibodies and cytokine release in response to challenge with M. leprae soluble antigen (MLSA). All of these patients remained anergic to Mitsuda lepromin. Lymphoproliferation in response to M. leprae antigen was noted in only two patients. Significant reduction in the phenolic glycolipid I (PGL-I) antibody response in treated patients with no difference in the M. leprae 35-kDa antibody response was observed when these responses were compared with those of active lepromatous patients. More treated patients produced interleukin-2 (IL-2) and interferon gamma (IFN-gamma) than did active patients. On the other hand, fewer treated patients produced IL-10 than did active patients. These limited findings suggest that the host immune response makes an attempt toward upregulation of CMI in some treated LL/BL patients.

Determination of circulating IgG subclasses against lipoarabinomannan in the leprosy spectrum and reactions.

IgG subclasses against lipoarabinomannan of mycobacteria were analyzed in the sera of leprosy patients. Patients with active leprosy [tuberculoid and lepromatous, patients undergoing erythema nodosum leprosum (ENL) and reversal reactions] and inactive cases (tuberculoid and lepromatous who were cured after chemotherapy) were included in this study. Active lepromatous patients had higher levels of IgG subclasses, except IgG4, compared to active tuberculoid patients. Some of the inactive cases (lepromatous patients cured after chemotherapy) were positive for the IgG1, IgG2 and IgG3 subclasses. However, their levels are lower than active lepromatous cases. On the other hand, no difference in the subclass levels between the active and inactive tuberculoid groups could be observed. While a significant fall in the level of IgG3 in ENL was observed as compared to lepromatous leprosy without ENL, higher levels of IgG1 and IgG2 were found in patients with reversal reactions compared to their active counterparts without reactions.

Levels of IgG subclasses in active and inactive cases in the disease spectrum of leprosy.

The present study was carried out to establish the role of IgG subclasses in leprosy. IgG subclasses to Mycobacterium leprae sonicated antigens (MLSA) and phenolic glycolipid-I (PGL-I) were determined in 124 patients with active leprosy across the disease spectrum and in 76 cases with inactive disease after completion of chemotherapy. IgG2 antibodies were found to be the predominant subclass across the disease spectrum. Lepromatous patients showed elevated levels of IgGI. IgG3 antibody levels were higher in lepromatous than that in tuberculoid patients. Patients with erythema nodosum leprosum showed a significant fall in IgG3 antibody to MLSA. While chemotherapy induced a reduction in IgG1, IgG2 and IgG3 to PGL-I in almost all types of leprous patients, for MLSA the reduction was noticed for these subclasses only in lepromatous patients. IgG4 responses to these antigens were low through out the disease spectrum and did not alter with chemotherapy.

Allergic reactivity and IgG subclasses to a proteinase fraction of Setaria digitata in filariasis.

A low molecular weight fraction (30 KDa) of the cattle filarial parasite Setaria digitata that was earlier demonstrated to have allergenic activity was characterized to be a zinc-dependent cysteine proteinase. Immediate type hypersensitivity (ITH) reaction to the proteinase was evaluated in lymphatic filariasis patients and in endemic controls from Orissa, India. The extent of ITH positivity to the proteinase in infected individuals ranged from 20% in chronic filariasis (CP) patients group to 56% in asymptomatic microfilaraemic carriers (AS). About 62% of endemic normals (EN) were also ITH positive. The serum levels of IgG subclasses were compared in ITH positive and ITH negative filarial patients (AS and CP) as well as in endemic normals (EN) respectively. IgG4 levels were found to be inversely dependent on ITH reaction only in AS groups. Asymptomatic patients (AS) with positive ITH reactivity had lower IgG4 than ITH negative individuals from the same group. The serum levels of other IgG subclasses except IgG2, did not correlate with ITH reactivity. IgG2 levels were higher in ITH negative EN and CP patients but not in the AS group.

Immunoglobulin E and G4 antibodies to infective larvae in a Wuchereria bancrofti endemic population.

IgE and IgG4 antibodies to infective larval antigen of W. bancrofti were measured by ELISA in filarial sera. IgE level was quite high in both infected and non-infected people living in filariae-endemic regions compared to people from non-endemic yet tropical regions. It was also demonstrated that IgE levels in amicrofilaraemic, normal children were lower compared to those of adults. Similarly IgG4 response in children was found to be reduced. The distribution of skin test (immediate hypersensitivity) reaction to larval antigen was not very extensive in people from endemic regions. Higher proportions of the normal population (39%) exhibited skin test reaction than either asymptomatic microfilaraemics or chronic patients (13% each). Specific IgG4 antibody was highly elevated in the sera of people with asymptomatic microfilaraemia. The rate of IgG4 seropositivity was 83% in microfilaraemic individuals compared to 20% in the normal population.

Human natural antibodies to Culex quinquefasciatus: age-dependent occurrence.

The titer of anti-Culex quinquefasciatus antibodies which were mostly of IgG and IgE isotypes was determined in humans living in Wuchereria bancrofti endemic regions. A progressive increase in the titer of antibodies was observed with age. In contrast, sera from people living in regions where the Cx. quinquefasciatus is of low prevalence were found to have markedly reduced IgG and almost zero IgE levels.

Dextran sulfate induced suppression of Plasmodium berghei parasitaemia.

Effect of dextran sulfate (DS, Mr 500,000) on parasitaemia in mice (Balb/c) infected with erythrocytic stage of P. berghei was investigated. Intraperitoneal injection of DS caused marked suppression of patent parasitaemia and also enhanced the survival time of the infected animals.

Stimulation by adjuvants of cell-mediated immune response in Plasmodium berghei infected mice.

Immunological adjuvants (alum, liposomes and saponin) were utilized to stimulate cell-mediated immune response in Plasmodium berghei infected Balb/c mice. It was shown that malaria antigen mixed with adjuvant induced appreciably delayed type hypersensitivity and production of migration inhibition factor compared to antigen alone.