Black fly (Simulium sp) composition, daytime biting activity and possible onchocerciasis infection in north-east, India.

Pupal stages of Simulium were collected and identified from various breeding habitats of twelve locations in northeastern India. Simulium flies, while attempting to land on human were collected between 07:00-17:00 hrs to understand the biting pattern. Seven species belonging to three sub-genera, Eusimulium (1), Gomphostilbia (1) and Simulium (5) belonging genus Simulium were encountered. Out of total seven species recorded, S. (E) aureohirtum, S. (G) tenuistylum and S. (S) rufibasis were predominant and shared 30.3%, 29.9% and 27.6% of total collection. Stream breeding habitat contributed 47.3% of total catch and was found to be preferred breeding habitat (p < 0.0001). S. (S) christophersi and S. (G) tenuistylum were recorded for the first time from the northeastern region of India. Simuliids biting rhythm showed bimodal pattern and were more active during sunny day (p < 0.0001). Microscopic dissection of simuliids (n = 266) did not incriminate simuliids as vector of onchocerciasis.

Influence of water physicochemical characteristics on Simuliidae (Diptera) prevalence in some streams of Meghalaya, India.

BACKGROUND & OBJECTIVES: Simuliids (Diptera) are one of the medically important biting insects group and have worldwide distribution. Their immature stages proliferate in fast flowing river or stream water and have been considered as important ecological indicator. METHODS: Aquatic stages of simuliids were collected and speciated from 16 different fresh water rivers and streams. Water flow rate was determined and water samples were analysed for various water variables such as water temperature, pH, dissolved oxygen concentration (DOC), dissolved oxygen saturation (DOS), conductivity, total dissolved solute (TDS), turbidity, resistivity and salinity. Linear regression was used to determine relationship between simuliid density and water variables, whereas multiple regression was used to determine the fitness for the presence of simuliid species. Principal component analysis (PCA) was used to determine the water parameters association with simuliid distribution. RESULTS: Total 565 specimens comprising of three species namely, Simulium (S) barraudi Puri, S. (S) striatum Brunetti, and S. (S) himalayense Puri were recorded in the present study. Simulium barraudi was the most abundant (56.8%) and its density was high (χ2 = 289.3; df = 2; p <0.0001) as compared to the others. The average population size of each species was 188.3, whereas Simpson and Shannon-Wiener diversity indices were 0.4466 and 1.306 respectively. Linear regression showed that simuliid density was associated with the water flow rate. Principal component analysis indicated that the water parameters accounted for 42.25% variation along D1 axis, while 24.1% variation along D2 axis. Atleast two principal components have eigenvalue >1 and accounted for 32.6% of variation. INTERPRETATION & CONCLUSION: Our study provides new information on simuliid species association with breeding water parameters in a little studied region of high biological interest. Turbidity, water flow and pH are important water parameters affecting the simuliid species prevalence. Each simuliid species preferred different sets of physicochemical parameters of breeding habitat, which are specific to that particular species. Therefore, simuliid species community as a whole cannot be considered as a suitable indicator of the streams water quality. In addition to describing simuliids, the information provided herein will be useful for the conservation of aquatic ecology and environment in Meghalaya state of India.

Immunomodulating effects and hypersensitivity reactions caused by Northeast Indian black fly salivary gland extract.

The genus Simulium, black fly (Diptera), comprises >1800 species worldwide, of which 67 species under six subgenera have been well studied in India. While at the extreme, black fly bites can cause onchocerciasis or river blindness, the majority of clinical observations indicate mainly severe pain and continuous itching at bite sites. This investigation experimentally observed that black fly salivary extract (BFSE) causes unique biologic effects including immunomodulation, anti-coagulation, and hypersensitivity reactions in Wistar rats. Salivary glands from black flies were isolated, extracted in saline, and then ≈800 ng extract (BFSE) subcutaneously injected into rats. To evaluate potential immunosuppressive activity of the BFSE, serum levels of interleukins [IL]-6 and -10 and tumor necrosis factor [TNF]-α were assayed. To assess the BFSE impact on coagulation, activated partial thromboplastin time (aPTT), prothrombin time (PT), and bleeding time, as well as generation of coagulation activated factors I, IX, and X were analyzed. Anaphylaxis induction was monitored via electrocardiogram (ECG) and measures of blood pressure and rectal temperature. The data showed that BFSE treatment resulted in a significantly prolonged aPTT, PT, and bleeding time and reversibly inhibited generation of coagulation activated factors I, IX, and X. The extract also led to a prolonged (up to 48 h) suppression of serum IL-6, IL-10, and TNFα production. While these results suggest that BFSE possesses anti-thrombotic, anti-coagulant, and immunomodulatory activities, importantly, they also indicate that the extract has a capacity to induce anaphylaxis and acute cardiotoxicity.

Vitex negundo inhibits cyclooxygenase-2 inflammatory cytokine-mediated inflammation on carrageenan-induced rat hind paw edema.

BACKGROUND: Vitex negundo L. (Verbenaceae) is a hardy plant widely distributed in the Indian subcontinent and used for treatment of a wide spectrum of health disorders in traditional and folk medicine, some of which have been experimentally validated. In present study, we aimed to investigate the anti-inflammatory effects of V. negundo in carrageenan-induced paw edema in rats, and to investigate the probable mechanism of anti-inflammatory action. MATERIALS AND METHODS: Paw edema was produced by injecting 1% solution of carrageenan, and the paw volume was measured before and after carrageenan injection up to 5 h. V. negundo leaf oil was extracted using a Clevenger apparatus and administered by a trans-dermal route to Wistar rats and the percentage of inhibition of inflammation was observed using a Plethysmometer by comparing a compound aerosol-based formulation with 1 mg diclofinac diethylamine BP and 7 mg methyl salicylate IP/kg body weight served as a standard drug whereas paraffin oil served as the placebo group. After withdrawing of blood, serum was separated and cyclooxygenase (COX)-1 and COX-2 inhibitory activities were measured by the enzyme immuno assay (EIA) method by using a COX inhibitor screening assay kit. RESULTS AND DISCUSSION: V. negundo leaf oil significantly (P < 0.05) reduced the carrageenan-induced paw edema as compared to the placebo group (paraffin oil) and 1 mg diclofinac diethylamine BP and 7 mg methyl salicylate IP showed the maximum inhibition of paw edema as compared to the V. negundo leaf oil treated group and the control group. Also in the present study V. negundo leaf oil showed significantly (P < 0.05) inhibits COX-1 pathways rather than COX-2 pathways as compared to the V. negundo leaf oil treated group. CONCLUSION: It is suggested that the V. negundo leaf oil is a potent anti-inflammatory agent and acts via inhibition of COX-2 without much interfering COX-1 pathways.