Diagnostic potential of monoclonal antibodies against the capsid protein of chikungunya virus for detection of recent infection.

Chikungunya fever is self-limiting. However, neurological and hemorrhagic complications have been seen in recent outbreaks. The clinical manifestations of this disease are similar to those of dengue virus infection, indicating the need for differential diagnosis in areas such as India, which are endemic for both viruses. The aim of the present study was to develop monoclonal antibodies (MAbs) against Chikungunya virus (CHIKV) and assess their use in MAb-based IgM capture ELISA (MAC ELISA). The ELISA detects CHIKV-specific IgM antibodies, a marker of recent infection, in a patient's serum. One IgG1 and two IgM isotype hybrids were obtained. All of the subclones derived from the IgG1 hybrid recognized the C protein of CHIKV. The anti-C MAb ClVE4/D9 was the most promising as a detector antibody in MAC ELISA (C-MAb ELISA) yielding higher positive-to-negative (P/N) ratios. When compared with the CHIKV MAC ELISA kit developed by the National Institute of Virology (NIV), Pune (NIV MAC ELISA), the sensitivity of the test was 87.01 % with 100 % specificity. The positive and negative predictive values (PPV and NPV) were 100 % and 94.47 %, respectively. In precision testing, standard deviation (SD) and coefficient of variation (% CV) values of the C-MAb ELISA were within acceptable limits. The C-MAb ELISA detected anti-CHIKV IgM in serum of patients up to five months after the onset of infection, indicating that anti-C MAbs have strong potential for use in MAC ELISA to detect recent CHIKV infection.

Susceptibility status of five species of Japanese encephalitis vectors to insecticides from Kolar district, Karnataka.

Susceptibility tests were conducted on the adults of five species of mosquito vectors of Japanese encephalitis (JE) viz., Culex tritaeniorhynchus, C. vishnui, C. pseudovishnui, C. gelidus and C. fuscocephala from Kolar district, Karnataka during 1990-91 against organo chloride compounds (DDT 4%, dieldrin 4%), organo phosphate compounds (malathion 5%, fenitrothion 1.0%), carbamate (propoxur 0.1%) and pyrethroid (deltamethrin--OMS 0.025%). All the five species were found susceptible to malathion. C. tritaeniorhynchus was resistant to DDT, dieldrin and fenitrothion; C. vishnui was also susceptible to fenitrothion and propoxur; C. pseudovishnui was resistant to dieldrin but it was susceptible to fenitrothion and propoxur. C. gelidus and C. fuscocephala were susceptible to dieldrin, fenitrothion and propoxur. Deltamethrin did not exhibit a good adulticidal effect except for C. pseudovishnui and C. fuscocephala. However, verifications are required to determine the susceptibility status of C. vishnui, C. pseudovishnui, C. gelidus and C. fuscocephala against DDT, C. tritaeniorhynchus against propoxur and C. vishnui against dieldrin.

Value of haemodynamic studies during pericardiocentesis in a cardiac catheterisation laboratory.

Pericardiocentesis was performed in 20 patients using a 7F diagnostic catheter in a cardiac catheterisation laboratory under fluoroscopic control, with haemodynamic and electrocardiographic monitoring. This technique offers several advantages over the bedside technique which utilises a sharp needle. The technique utilised for percutaneous aspiration is safe and simple and allows complete drainage of fluid. The haemodynamic monitoring before and after drainage aids in detecting cases of effusive constriction.

Infective endocarditis following balloon dilatation of mitral valve.

Three cases of infective endocarditis were encountered following balloon dilatation of the mitral valve. The diagnosis was difficult due to negative blood cultures and nondiagnostic transthoracic echocardiogram, the latter the consequence of the preexisting severe rheumatic valvar disease. Transoesophageal echocardiography proved superior in diagnosis. The possible causes and means of preventing this potentially lethal complication are discussed.

Susceptibility studies on Culex tritaeniorhynchus Giles, 1901, to insecticides in the state of Goa.

Tests conducted on the adults of C. tritaeniorhynchus in Goa during 1988-89 against organochlorine, organophosphate and carbamate insecticides showed that the LC50 values against DDT and dieldrin after 1 h of exposure were 2.2 and 1.2 per cent respectively. The LT50 values against malathion (5%), fenitrothion (1%) and propoxur (0.1%) were 19, 22 and 35 min respectively. Thus, taking into consideration the base-line data available for C. quinquefasciatus, the species can be considered susceptible to dieldrin, malathion, fenitrothion and propoxur. However, the results with DDT were equivocal and require verification.

Isolation of Japanese encephalitis virus from Culex pseudovishnui Colless, 1957 (Diptera: Culicidae) in Goa.

A strain of Japanese encephalitis virus was isolated from a pool of 54 female C. pseudovishnui Colless, 1957. The mosquitoes were collected in August 1988 during the period of epidemic of JE. This is the first report of isolation of JE virus from mosquitoes in Goa in the western coastal belt of peninsular India. In view of this isolation, C. pseudovishnui acquires greater importance, even though its density and relative prevalence during the current study was found to be far lower than C. tritaeniorhynchus.

Density patterns of anophelines and their relation to malaria in Bastar district, Madhya Pradesh.

Density patterns of 17 species of anopheline mosquitoes collected between 1980 and 1981 from indoor and outdoor resting places of a highly malarious area of Bastar district, Madhya Pradesh are given. A. culicifacies and A. fluviatilis are the important vector species in the region. The former was highly endophilic and found throughout the year and its man hour density (MHD) ranged from 7.6 to 78 with peaks in February and July. The latter was highly exophilic, also found throughout the year. Its density ranged from 1.6 to 7.0 per 10 man hours with a peak in July/August. A. subpictus was considered as potential vector species, found throughout the year and was endophilic, having MHD ranging from 0.9 to 148 with peaks in February-March and July-August. The MHD variations of other species were; A. aconitus (0.02-1.04), A. annularis (0.02-10.4), A. barbirostris (0.04-1.07), A. hyrcanus (1.30-1.86), A. jamesii (0.01-0.46), A. jeyporiensis (0.01-1.06), A. karwari (0.01-0.04), A. maculatus (0.01-0.03), A. pallidus (0.02-2.4), A. splendidus (0.02-0.32), A. tessellatus (0.02-0.12), A. theobaldi (0.01-0.03), A. vagus (0.01-2.3) and A. varuna (0.03-0.31). Results of gut and gland dissections showed correlation of infection with the occurrence of peak vector densities. The density levels and seasonal activities of vectors as well as potential vector species are favourable for perennial transmission of malaria in Bastar district.

Breeding habitats of mosquitoes in Goa.

Studies carried out in Goa from 1986 to 1987 revealed immature stages of 43 species of mosquitoes. Breeding habitats were divided into three categories, viz., (i) Ground water habitats consisting of ground pools and tanks, rocky pools, paddy fields and stream beds, yielding 30 species; (ii) Plant habitats consisting of tree holes and fallen coconut shells and leaf sheaths yielding 20 species; and (iii) Domestic/peridomestic habitats consisting of cement tanks, glass, earthen, metallic containers and tyres yielding 11 species. Five species viz., Anopheles subpictus, Aedes albopictus, Armigeres subalbatus, Culex quinquefasciatus and Cx. pallidothorax were found in all three types of habitats. Cx. tritaeniorhynchus preferred to breed in ground pools and paddy fields but was found in domestic cement tanks and ground tanks in adverse season. Majority of the anophelines and culicines were found in ground water habitats. Five out of 11 species of Aedes were found in tree holes. Aedes aegypti and Toxorhynchites splendens were found only in discarded tyres. Three species of the genus Uranotaenia, viz., U. bicolor, U. stricklandi and U. campestris were recorded from stream beds and plant containers.