A comparative study of prevalence and spatial distribution of major Anopheline vector fauna in a hyper- and a hypomalaria endemic district of Odisha, India with special reference to onset of first wet season.

The state's retrospective findings indicate the incidence of malaria deaths, which is more during the onset of first monsoon season. Based upon this fact, our objective was to study the distribution pattern of major Anopheles vectors in two endemic districts viz. Kalahandi and Cuttack of Odisha, India that differ significantly according to malariogenic stratification, under the impact of first monsoon shower. A comparative study of vector abundance, predominance, their habitats, resting site preference, impact of abiotic rhythm (light/dark period) on vector distribution, gonotrophic status as well as sporozoite rate was established in a high and a low endemic district of Odisha, when the degree of malaria transmission elevates to its peak level Anopheles culicifacies was found to be predominant in hyperendemic Kalahandi district while Anopheles subpictus was abundant in hypo-endemic Cuttack district. Both primary vector An. culicifacies and the secondary vector An. subpictus mostly prefer CS (Cattle shed) compared to HD (Human dwelling) in Kalahandi district where as there was slight shifting of resting habitat of An. culicifacies from CS to HD in Cuttack district. Anopheles culicifacies prefers to rest on wall besides objects in Kalahandi while no such site preference was observed in Cuttack district. On the other hand, distribution of An. subpictus was highly influenced by the daily rhythm of light/dark cycle (i.e. day and night) in Cuttack. The gonotrophic condition revealed the high tendency of the predominant vectors towards endophilic resting. The sporozoite rate was 0.66% in Kalahandi and nil in Cuttack district. The proper monitoring of vector prevalence and distribution, at least during the peak transmission period can avert a perpetuated upsurge in malaria.

Perennial malaria transmission and its association with rainfall at Kalahandi district of Odisha, Eastern India: A retrospective analysis.

India contributes substantially to global malaria incidents. Vector dynamics is the significant determinant of malaria risk. Hence, knowledge on the interaction between rainfall, malaria cases and malaria vector density can be very useful for controlling malaria transmission. Kalahandi was screened for malaria cases, Anopheline vector density and their temporal relationship with rainfall. Epidemiological data was obtained from National Vector Borne Disease Control Programme, Odisha, India. Three years vector population study was carried out. Rainfall data was obtained from a database maintained by the Govt. of Odisha and was analysed using Univariate ANOVA and Pearson correlation co-efficient tests using R-prog. Malaria was found to be prevalent throughout the year attaining peak between July to August and another peak in December, amidst which the clinical malaria cases being recorded implied highest incidents in the month of July. The results estimated the seasonality of the population of An. culicifacies, An. fluviatilis and An. annularis over the region and determined the influence of rainfall on the vector population dynamics. Simple linear regression analysis suggested that at one month lag monthly rainfall (P=0.0007) was a significant meteorological factor. Rainfall seemed to be one of the best malaria predictors because of its positive correlation with proliferation of malaria cases in conjunction with An. culicifacies density making malaria a serious health issue in Kalahandi.

Perennial malaria transmission and its association with rainfall at Kalahandi district of Odisha, Eastern India: A retrospective analysis

@#India contributes substantially to global malaria incidents. Vector dynamics is the significant determinant of malaria risk. Hence, knowledge on the interaction between rainfall, malaria cases and malaria vector density can be very useful for controlling malaria transmission. Kalahandi was screened for malaria cases, Anopheline vector density and their temporal relationship with rainfall. Epidemiological data was obtained from National Vector Borne Disease Control Programme, Odisha, India. Three years vector population study was carried out. Rainfall data was obtained from a database maintained by the Govt. of Odisha and was analysed using Univariate ANOVA and Pearson correlation co-efficient tests using R-prog. Malaria was found to be prevalent throughout the year attaining peak between July to August and another peak in December, amidst which the clinical malaria cases being recorded implied highest incidents in the month of July. The results estimated the seasonality of the population of An. culicifacies, An. fluviatilis and An. annularis over the region and determined the influence of rainfall on the vector population dynamics. Simple linear regression analysis suggested that at one month lag monthly rainfall (P=0.0007) was a significant meteorological factor. Rainfall seemed to be one of the best malaria predictors because of its positive correlation with proliferation of malaria cases in conjunction with An. culicifacies density making malaria a serious health issue in Kalahandi.

A comparative study of prevalence and spatial distribution of major Anopheline vector fauna in a hyper- and a hypomalaria endemic district of Odisha, India with special reference to onset of first wet season

@#The state’s retrospective findings indicate the incidence of malaria deaths, which is more during the onset of first monsoon season. Based upon this fact, our objective was to study the distribution pattern of major Anopheles vectors in two endemic districts viz. Kalahandi and Cuttack of Odisha, India that differ significantly according to malariogenic stratification, under the impact of first monsoon shower. A comparative study of vector abundance, predominance, their habitats, resting site preference, impact of abiotic rhythm (light/dark period) on vector distribution, gonotrophic status as well as sporozoite rate was established in a high and a low endemic district of Odisha, when the degree of malaria transmission elevates to its peak level Anopheles culicifacies was found to be predominant in hyperendemic Kalahandi district while Anopheles subpictus was abundant in hypo-endemic Cuttack district. Both primary vector An. culicifacies and the secondary vector An. subpictus mostly prefer CS (Cattle shed) compared to HD (Human dwelling) in Kalahandi district where as there was slight shifting of resting habitat of An. culicifacies from CS to HD in Cuttack district. Anopheles culicifacies prefers to rest on wall besides objects in Kalahandi while no such site preference was observed in Cuttack district. On the other hand, distribution of An. subpictus was highly influenced by the daily rhythm of light/dark cycle (i.e. day and night) in Cuttack. The gonotrophic condition revealed the high tendency of the predominant vectors towards endophilic resting. The sporozoite rate was 0.66% in Kalahandi and nil in Cuttack district. The proper monitoring of vector prevalence and distribution, at least during the peak transmission period can avert a perpetuated upsurge in malaria.

Mosquito diversity in the Chilika lake area, Orissa, India.

Twenty-two species of mosquitoes belonging to six genera (Anopheles, Aedeomyia, Aedes, Armigeres, Culex and Mansonia) were collected from eight villages in and around the Chilika lake area, Khurda and Puri Districts from 2006-2007. Greater numbers of the culicines (65.59%) were collected from the area, as compared with the anophelines (34.4%). Mansonia indiana and Mansonia dives were reported for the first time from the area. The values of the species richness (S), Shannon Index (H), and Shanon evenness (Es) between anophelines and culicines were 10, 12; 0.89, 1.85; 0.38, 0.74, respectively. Based on biostatistical analysis, the culicines were more diverse than anophelines in the study area.

Effect of construction of an irrigation canal on malaria situation in two primary health centres of Dhenkanal district of Orissa, India.

To assess the impact of irrigation canals on malaria transmission, a study was conducted in Dhenkanal district of Orissa, India. The district is situated in the central part of Orissa and hyperendemic area for malaria. A canal system is being constructed for irrigation in the district, which passes through Parjang and Analabereni Primary Health Centres (PHC), endemic for malaria. The water has been released only up to Parjang (Canal with water -CWW) area during the end of 2004 and construction work is still going on in Analabereni PHC (Canal under construction-CUC). Retrospective clinical data (2001-2008) collected from health services from two study sites showed average Slide Positivity Rate (SPR) before release of water (2001-2004) was 9.25% and 18.04% in CWW and CUC areas, respectively. After release of water (2005-2008) the SPR was 5.77% and 10.19%, in CWW and CUC areas, respectively. The average Annual Parasite Incidence (API) was 7.66 and 22.67 in CWW and CUC areas before the release of water and 5.32 and 12.28 after release of water, respectively. A point fever survey was conducted in 2009 which revealed the presence of Plasmodium falciparum (Pf) and P. vivax (Pv) in both study areas. The survey found SPR of 18.82% and 24.54%, and Pf percentages of 75% and 85%, in CWW and CUC areas, respectively. The present study revealed the presence of two malaria vectors, Anopheles culicifacies and Anopheles annularis in the area. Vector Per Man Hour Density was 2.38 in CWW and 2.69 in CUC for An. culicifacies and 1.46 and 1.54 for An. annularis respectively. The sporozoites rates were found to be 3.6 and 3.8 for CWW and CUC, respectively. The present study reveals that, the construction of canal system did not increase the malaria prevalence during post water release period - implying that the malaria control programme was effective although still more intensive situation specific vectors control programme need to be continued simultaneously so that malaria transmission can be curtailed.

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.

An efficient PCR--SSCP-based method for detection of a chloroquine resistance marker in the PfCRT gene of Plasmodium falciparum.

The spread of chloroquine resistance throughout the world poses a major problem in combating malaria. In the present study, an efficient polymerase chain reaction-single strand conformational polymorphism (PCR--SSCP)-based assay detected the PfCRT K76T point mutation, which is a marker for chloroquine resistance. For the first time, we have used a PCR--SSCP-based technique to identify the mutation in a single-step labelling reaction during PCR and SSCP gel electrophoresis. This assay is 100% efficient, giving no false-positive or -negative results, and can be carried out within a short bench time. We have successfully analysed 120 natural isolates using the PCR-SSCP method for detection of the chloroquine resistance marker and found 91 of the 120 samples to show the PfCRT T76 mutation, and 71% (65 of the 91 samples) showed a positive correlation with chloroquine resistance from the clinical data of the patients. The PCR-SSCP technique can also be applied for the detection of new haplotypes of the PfCRT gene and surveillance of chloroquine-resistant malaria in malaria-endemic localities around the world.

Host feeding patterns of malaria vectors of Orissa, India.

Blood meals of 1,491 Anopheles fluviatilis sensu lato (s.l.), 1,690 An. culicifacies s.l., 719 An. annularis s.l., and 358 An. varuna sensu stricto were examined by gel diffusion method. The overall anthropophilic index (AI) was 78.9%, 1.6%, 3.2%, and 6.7% for An. fluviatilis, An. culicifacies, An. annularis, and An. varuna, respectively. Out of 4 anopheline species studied, only 0.2% of An. culicifacies blood meals contained blood from humans and cattle. Anopheles fluviatilis and An. culicifacies revealed seasonality in their anthropophilic index. An. fluviatilis showed a human forage ratio of more than 1, whereas An. culicifacies, An. annularis, and An. varuna had forage ratios of 2.6, 2.5, and 2.4, respectively, for bovine. There was a correlation between the Al of An. fluviatilis and the malaria slide positivity rate. This study suggests that the use of repellent, insecticide-treated nets will be effective for controlling biting mosquitoes inside houses in Orissa.

A simple, artificial-membrane feeding method for the radio-isotope labelling of Aedes aegypti polypeptides in vivo.

An artificial feeding unit has been designed and constructed to feed laboratory-bred Aedes aegypti with a radio-isotope (35S), so that the mosquitoes' polypeptides can be labelled in vivo. In the unit, a piece of Parafilm M barrier film is stretched over the bottom, outer surface of a polystyrene Petri dish, to create a small gap in which the mixture of blood and radio-isotope is placed. Warm water is placed in the dish, to keep the blood at about 37 degrees C. When such units were placed on net-covered rearing cages, almost all (80%-90%) of the female mosquitoes in the cages took bloodmeals from them. When checked by polyacrylamide-gel electrophoresis and autoradiography 1 h after feeding had begun, the blood-fed mosquitoes were found to have radio-labelled polypeptides. The unit is simple, easy to handle, disposable and can be used to offer small blood samples (>or=50 microl) to Ae. aegypti and, presumably, other mosquito species.

Combined detection of Brugia malayi and Wuchereria bancrofti using single PCR.

A single step PCR method has been developed for the combined detection of the human filarial parasites, Brugia malayi and Wuchereria bancrofti. Parasites' DNA were isolated from filaria positive blood samples that were collected from endemic areas. The primers used were Hha1 and Ssp I, which amplified the DNA fragments of 322 bp and 188 bp specific to B. malayi and W. bancrofti, respectively. The sensitivity of the assay was tested with blood and mosquito samples having one W. bancrofti in a pool of 10 B. malayi. The assay was further evaluated on field collected blood and mosquito samples. Use of this assay as a diagnostic tool for the detection of filariasis being the most promising aspect of this study, offers scope for detection of both the parasites even at low levels of infection.

Knowledge and beliefs about elephantiasis and hydrocele of lymphatic filariasis and some socio-demographic determinants in an endemic community of Eastern India.

This study reports the knowledge and beliefs about filarial elephantiasis and hydrocele of people from an endemic area of Orissa, India. Both qualitative and quantitative data were collected from 12 villages, sampled from four blocks in the Khurda district of Orissa. This study found that people were aware of different manifestations of filariasis, and perceived them as problems in their community. A high proportion of people knew that mosquitoes are the reason for the spread of elephantiasis, but less people were aware of the cause of hydrocele and the association between elephantiasis and hydrocele. Only half of the respondents believed that elephantiasis is curable by modern medicines, and about 84% of respondents thought that surgery is the only method to cure hydrocele. About two-thirds of people know that avoiding mosquitoes can prevent elephantiasis. Age, gender, educational level and caste affiliation were identified as factors influencing awareness and knowledge. These findings may be used in the development of group-specific health education programmes to change health behaviour and to achieve higher involvement of the community in annual mass drug administration to eliminate lymphatic filariasis.

Retrospective analysis of epidemiological investigation of Japanese encephalitis outbreak occurred in Rourkela, Orissa, India.

There was an outbreak of Japanese encephalitis (JE) during July/August of 1993 in Rourkela City of Orissa, India. Among the serum samples, 40% of the sera showed antibodies against JE, while 17% of the sera showed recent infection to dengue virus. As many as 15 species of mosquitos were encountered in and around the affected areas. Species like Culex tritaeniorhynchus, Cx, vishnui, Cx. pseudovishnui and Cx. bitaeniorhynchus constituted 19% of the total collections. The above species were resistant to DDT and dieldrin, but susceptible to malathion.

Disappearance of malaria vector Anopheles sundaicus from Chilika Lake area of Orissa State in India.

Malaria has declined around Chilika Lake (85 degrees 20'E, 19 degrees 40'N) in Orissa State, India, from hyperendemicity in the 1930s to hypoendemicity during recent decades. Six decades ago, 21 spp. of Anopheles mosquitoes (Diptera: Culicidae) were recorded from this area, including the well known Indian malaria vectors An. culicifacies Giles, An. fluviatilis James, An. maculatus Theobald, An. stephensi Liston and An. sundaicus (Rodenwaldt), the last formerly regarded as the main vector locally. Surveys of Chilika area during 1995-96 found 8 spp. of culicine plus 14 spp. of anopheline mosquitoes, the latter comprising An. subpictus Grassi sensu lato, An. hyrcanus (Pallas) s.l., An. vagus Dönitz, An. annularis van der Wulp s.l., An. culicifacies Giles s.l., An. aconitus Dönitz, An. varuna Iyengar, An. barbirostris van der Wulp s.l., An. philippinensis Ludlow, An. ramsayi Covell, An. jeyporiensis James, An. pallidus Theobald, An. tessellatus Theobald and An. karwari James in decreasing order of abundance. Among indoor-resting female mosquitoes, the anthropophilic index was 4-7% and some species (An. culicifacies, An. subpictus, An. vagus) tended to enter houses for resting after blood-feeding outside. Females of potentially infective age (three-parous) were obtained for An. culicifacies (11%) and An. annularis (<2%), the more abundant established vector in this coastal area, but not for small samples of An. subpictus and An. vagus. Anophelines reported previously but not found in our survey were An. fluviatilis, An. jamesii Theobald, A. maculatus, An. splendidus Koidzumi, An. stephensi, An. theobaldi Giles and the former main vector An. sundaicus.

Bacillus sphaericus interferes with the development of Brugia malayi in Aedes aegypti.

Aedes aegypti (black-eyed Liverpool strain) were exposed to a sublethal dose (LD25) of Bacillus sphaericus and were fed to Mastomys coucha infected with Brugia malayi. The development of the filarial parasite was found to be arrested mostly at the second larval stage. The infection (P < 0.05), infectivity rates (P < 0.001) and L3 load (P < 0.001) were found to be reduced significantly in the treated group.

Transmission dynamics of filariasis in Khurdha district of Orissa, India.

A three year longitudinal study was carried out to quantify the different parameters of filarial transmission in an endemic area of Orissa State, India. Parasitological surveys revealed mean microfilaria rate, microfilaria density and median microfilaria density (MFD-50) to be 9.41, 19.23 and 7.33, respectively. The per man hour density of the vector, Culex quinquefasciatus varied from 24.2 to 66.0 with a peak in January. Infection rate varied from 0.9 to 27.5%, while infectivity rate ranged between 0.0 and 15.2%. Infectivity rate showed high correlation with microfilaria rate and per man hour density of adult mosquito. The highest numbers of first stage larvae (L1), second stage larvae (L2) and third stage larvae (L3) per mosquito were found to be 25, 22 and 11, respectively. Average L3 load per infective mosquito ranged from 1.0 to 7.2. L3 load showed high correlation with microfilaria rate (r = 0.845, p < 0.01) while no correlation was seen with microfilaria density.