Anthropophily of Anophelines in Duars of West Bengal and other regions of India.

Attempts have been made to identify the source of blood meals of twenty three anopheline species from various areas of high malaria endemicity in India. Anopheles minimus, Anopheles fluviatilis and Anopheles dirus showed a high propensity for human blood in North-Eastern parts of the country while Anopheles sundicus was found to be anthropophilic in Andaman & Nicobar Islands. Anopheles culicifacies, Anopheles maculatus and Anopheles philippinensis were found primarily zoophilic in north-eastern areas. High anthropophily has been closely related to sporozoite infection in anophelines specially in Anopheles minimus and is of great epidemiological significance.

Efficacy of chloroquine in febrile Plasmodium falciparum infected children in Mewat region of Haryana.

During 1996, Mewat region of Gurgaon district in Haryana experienced high incidence of Plasmodium falciparum malaria, assuming epidemic proportion in large number of villages affected by floods. Mortality due to fever was also high. In vivo 7 days study amongst 32 febrile P. falciparum infected children of 1 to 14 years age group in flood affected villages of Ferozpur Jhirka Community Health Centre of Mewat region was carried out. All the 32 cases showed good response to chloroquine suggesting that drug was effective and useful as first line of treatment, reducing severity of P. falciparum infection and resolving fever due to infection of the species. The study also indicated that chloroquine was an effective drug in controlling epidemic situation and mortality in areas of high incidence of P. falciparum. Pyrogenic stimulus was variable among different developmental stages of P. falciparum and suggestive of the need of earliest possible initiation of anti-malaria treatment, community based fever survey and blood smear examination. Increase in incidence of fever in an endemic community, particularly in children, should be considered as an indicator of impending outbreak of P. falciparum malaria. Effectiveness of diagnostic and control measures taken can be evaluated on the basis of incidence of malaria particularly due to P. falciparum infection and also incidence of fever in an endemic community.

Ecological observations on the anopheline mosquitoes of Jalpaiguri Duars, West Bengal.

A nine month entomological study was conducted from August 1989 to April 1990 in Jalpaiguri duars of West Bengal where malaria has been persistent problem. Amongst the anopheline fauna three vector species were recorded; An. minimus was the principal vector supported by A. dirus during the rainy months and An. fluviatilis in dry months. All the three vectors were found in close association with human orbit and An. minimums was found to be primarily a domestic vector. The primary role of An. minimus in the transmission of malaria in the region has been highlighted. Observations on seasonal variation, biting preferences, and biting time and vector infection rates were recorded.

Chloroquine versus amodiaquine in the treatment of Plasmodium falciparum malaria in northeast India.

Amodiaquine is being used in India for presumptive treatment as an alternative to chloroquine in areas with chloroquine resistant P. falciparum. Keeping in view the toxicity of amodiaquine, studies have been undertaken to evaluate the advantage of the drug over chloroquine in the treatment of P. falciparum malaria. In vivo drug resistance studies were carried out in the states of Assam and Meghalaya in India. A total of 388 subjects have been studied to compare the efficacy of chloroquine and amodiaquine. The overall cure rate, degree of resistance, mean parasite clearance time and mean parasite recrudescence time were comparable for both the drugs, the differences being not statistically significant. The results indicate no advantage of amodiaquine in the treatment of patients with P. falciparum infection in chloroquine resistant areas of northeast India and development of cross resistance in P. falciparum to these 4-aminoquinolines is complete and parallel.

Human immunodeficiency virus-1 infection in spouses of seropositive individuals.

BACKGROUND. Unprotected sex can lead to transmission of the human immunodeficiency virus-1 (HIV-1) to the spouse of an infected individual. We studied the incidence of HIV-1 infection in the spouses of cases diagnosed to have HIV-1 infection by serology and the polymerase chain reaction (PCR). METHODS. Blood samples collected from 9 index cases and their respective spouses were tested for HIV-1 infection by ELISA, Western blot (WB) and PCR as well as from 10 healthy individuals with no high-risk behaviour. DNA extracted from both plasma and peripheral blood mononuclear cells was amplified by PCR, using multiple primer pairs for distinct regions of the HIV-1 genome. Specificity of the PCR product was demonstrated by hybridization to an oligonucleotide probe. RESULTS. All the index cases which were seropositive by ELISA and WB were also positive by PCR of plasma extracted DNA. Eight of the spouses were seronegative. Of these seven were positive by PCR--one spouse was negative by ELISA but showed a p55 band on WB and was positive by PCR. One spouse was negative by serology and PCR. The spouse belonging to the lone concordant couple was positive by serology and PCR. Except for one index case, PCR signals were obtainable only from DNA extracted from plasma but not from the DNA extracted from peripheral blood mononuclear cells. The control samples were negative by serology and PCR. CONCLUSION. It is possible to detect HIV-1 infection by PCR using DNA extracted from plasma even when the individuals are negative by ELISA and WB. It can help in the early counselling of HIV infected persons and their spouses.

Malaria transmission in Nagaland, India. Part-I--Anophelines and their seasonality.

A longitudinal study on malaria transmission was conducted from January 1983 to December 1988 in two villages of Dimapur PHC in Nagaland. A diverse anopheline fauna comprising of 23 species was identified including three species viz. An. aitkeni, An. bengalensis and An. insulaeflorum which were observed in larval stages only. An. vagus was the predominant species followed by An. philippinensis, An. culicifacies and An. minimus. An. minimus though maintained relatively high density throughout the year manifested two peaks in June and October. An. fluviatilis and An. dirus though found in relatively low density their seasonal prevalence was suggestive of a post-monsoon and monsoon species respectively.

Present perspectives of malaria transmission in Boko area of Assam.

A longitudinal study on malaria transmission was conducted from January 1984 to December 1988 in three villages in Boko PHC of Assam, where indoor residual DDT spray was withdrawn during the period of study. Anopheline fauna comprising of 19 species was identified and their seasonal density estimated. Anopheles philippinensis was the predominant species followed by An. minimus. The principal role of An. minimus in the transmission of malaria and predilection for indoor resting in this area was clearly evident. Though An. dirus and An. fluviatilis were found in low density, sporozoite infection was detected in them along with An. minimus. The high malaria incidence predominantly with Plasmodium falciparum was closely related to sporozoite infection in the vectors and their densities. The biting cycle of An. minimus was maximum in the first half of the night.

Detection of hepatitis B virus DNA in donor blood by the polymerase chain reaction.

BACKGROUND. Blood collected from voluntary donors at local blood banks and blood donation camps was screened for the hepatitis B virus genome using the polymerase chain reaction and for viral markers by standard serological techniques. The sensitivities of the two screening strategies were compared. METHODS. One hundred and twenty-six blood samples were tested for HBV serological markers--HBsAg, anti-Hbs and anti-HBc--by ELISA. The same samples were also subjected to the polymerase chain reaction using primers made by us. RESULTS. Analysis of the polymerase chain reaction amplified products revealed that 24% of the blood samples which tested negative for HBsAg using the ELISA technique were positive for HBV DNA by the polymerase chain reaction. All the HBsAg positive samples (by ELISA) were also positive by the polymerase chain reaction (which detected additional samples as well). Anti-HBc antibodies showed a much greater concordance with the polymerase chain reaction. CONCLUSIONS. The results emphasize that the screening strategies for donor blood need to be re-evaluated in order to check inadvertent transmission of hepatitis B virus during blood transfusion. The ELISA technique to detect HBsAg as the sole serological marker is inadequate to indicate the actual prevalence of hepatitis B virus in the donor blood. The polymerase chain reaction may be a better screening test. If this is not available, the detection of anti-HBc antibodies appear to be a better means of screening blood than HBsAg.

Purification of antigen for serodiagnosis of echinococcosis.

Antigen for serodiagnosis of Echinococcosis is purified by chromatography on DEAE-Cellulose and Sephadex G-200 from hydatid cyst fluid. The antigen is electrophoretically pure and found sensitive and specific for Echinococcus granulosus. The antigen is thermostable and is apparently a lipo protein.

Characterization of third beta-chain variant in Rattus rattus rufescens.

Different molecular forms of hemoglobins of locally available murines, represented by Rattus rattus rufescens, have been investigated and the probable genetic mechanisms leading to the observed heterogenicity in the hemoglobin phenotypes are discussed. Each fraction was isolated in chromatographically pure form, identified and characterised structurally to establish their alpha- and non-alpha-chain constitution. Six molecular forms of component hemoglobins were identified from a wild population of R. rattus rufescens. The present study suggests five different globin chains in the hemoglobin of house rats (Rattus rattus rufescens). There are apparently two alpha-chains, namely alpha I and alpha II, and three different beta-chains, viz. beta I, beta II and beta III. The invariable presence, though at varying concentrations, of all these five globin chains implicates a gene duplication at the alpha-chain loci and a gene triplication at the beta-chain loci, the latter being a rather rare and unique genetic event.

Evolutionary trends in the hemoglobins of murine animals.

The evolutionary origin of murine line based on a phylogenetic tree made on sequence data of ∝-and β-hemoglobin chains, followed by the diversity spectrum of hemoglobin genes in two wild species of murine rodents: Rattus rattus rufescens (house rat) and Bandicota indica (bandicoot rat) has been reported. Each house rat contains six hemoglobin types involving two ∝-and three β-chains, which suggests a probable gene duplication at the ∝ chain locus and a gene triplication at the β-chain locus. Each bandicoot rat contains one ∝-and two β-chains suggesting a probable gene duplication at the β-chain locus. Peptide pattern analysis of the polypeptide chains of these murine hemoglobins further indicates that intraspecies differences among duplicated chains of the same kind are less than interspecies differences among corresponding ∝- and β-chains.