Toxicological effects of prolonged and intense use of mosquito coil emission in rats and its implications on malaria control / Efectos toxicológicos del uso prolongado e intenso de emisiones de espirales contra mosquitos en ratas y sus implicaciones sobre el control de la malaria

Efectos toxicológicos del uso prolongado e intenso de emisiones de espirales contra mosquitos en ratas y sus implicaciones sobre el control de la malaria. Mosquito coil is a vector control option used to prevent malaria in low income counties, while some studies have addressed this issue, additional reseach is required to increase knowledge on the adverse health effects caused by the prolonged use of coils. In this study we investigated the toxicological effects of fumes from two locally manufactured mosquito coil insecticides (with pyrethroids: transfluthrin and d-allethrin as active ingredients) on male albino rats. For this, we recorded the haematological and biochemical indices, and made histopathology and mutagenicity evaluations in rats exposed to mosquito fumes during 2, 4, 8, 12 and 16 week periods. Haematological determination was performed using automated hematology analyzer to determine White Blood Cell (WBC), Packed Cell Volume (PCV), Red Blood Cell (RBC) and Platelet (PLT) counts, while biochemical evaluations were determined using available commercial kits. Gross histopathological changes were studied for the kidney, liver and lungs in sacrificed rats. The rat sperm head abnormalities assessment was used to evaluate mutagenicity. Mosquito coil fumes produced significant increase (P<0.05) in the levels of total protein, total albumin and bilirubin, when animals were exposed from two weeks to 16 weeks with transfluthrin. Similarly, elevation in the activities of aspartate amino transferase, alanine amino transferase and alanine phosphatase, increased significantly in both insecticides. Increase in WBC, RBC and PCV were recorded for all the exposure periods, however PLT count showed no significant increase (P>0.05). Mutagenicity assessment revealed sperm abnormality was statistically significant (P<0.05) compared with the control at 8, 12 and 16 weeks post exposure to transfluthrin. Histological studies revealed severe lung damage evidenced by interstitial accumulations, pulmonary oedema and emphysema in exposed rats. Intracellular accumulations and severe sinusoidal congestion of liver cells were observed from 12 weeks exposure, indicating liver damage. Our studies indicate that mosquito coil fumes do initiate gradual damage to the host. These pathological effects must be taken into consideration by the malaria control program, particularly when regulating their long term and indoor usage.

Las espirales contra los mosquitos se utilizan en los países de bajos ingresos como una opción para prevenir la malaria controlando el vector de esta enfermedad. A pesar de que algunos estudios han abordado este tema, se requiere más investigación para incrementar el conocimiento sobre los efectos adversos en la salud, causados por el uso prolongado de las espirales. En este estudio se investigaron los efectos toxicológicos de los gases de las espirales a partir de dos insecticidas fabricados en el país (con piretroides: transflutrina y d-aletrina como ingredientes activos) en machos de ratas albinas. Para esto, se registraron los índices hematológicos y bioquímicos, y se hicieron evaluaciones histopatológicas y de mutagenicidad en ratas expuestas a los gases de las espirales durante períodos de 2, 4, 8, 12 y 16 semanas. La determinación hematológica se realizó mediante un analizador de hematología automatizado para determinar el conteo de los Glóbulos Blancos (WBC), el Hematocrito (PCV), Glóbulos Rojos (RBC) y las Plaquetas (PLT), mientras que las evaluaciones bioquímicas se determinaron utilizando kits comerciales disponibles. Los cambios histopatológicos fuertes se estudiaron en el riñón, el hígado y los pulmones de ratas sacrificadas. Las anormalidades en la cabeza de los espermatozoides de las ratas se utilizaron para evaluar la mutagenicidad. El humo de las espirales contra los mosquitos producen un aumento significativo (p<0.05) en los niveles de proteína total, albúmina total y bilirrubina, cuando los animales fueron expuestos de dos semanas a 16 semanas con transflutrina. Del mismo modo, la elevación en las actividades de aspartato amino transferasa, alanina amino transferasa y alanina fosfatasa, aumentó significativamente con ambos insecticidas. Se registro un aumento en los leucocitos, eritrocitos y el hematocrito para todos los períodos de exposición, sin embargo el recuento de las plaquetas no mostró un aumento significativo (p>0.05). Las pruebas de mutagenicidad revelaron que las anormalidades en el esperma de las ratas fue estadísticamente significativa (p>0.05) al comparar el control a las 8, 12 y 16 semanas post exposición a la transflutrina. Los estudios histológicos revelaron una serie de daños pulmonares graves en las ratas expuestas al humo de la espiral, evidenciados por la acumulación intersticial, edema pulmonar y enfisema. Las acumulaciones intracelulares y la congestión sinusoidal severa de las células del hígado se observaron a partir de las 12 semanas de exposición, lo que indica daño hepático. Nuestros estudios indican que los vapores de las espirales contra mosquitos inician el daño gradual al huésped. Estos efectos patológicos deben ser tomados en cuenta por el programa de control de la malaria, particularmente a la hora de regular su uso a largo plazo y bajo techo.

Ultrastructural study of the effect of inhalation of mosquito-coil smoke on the interalveolar septum of the lung of rat

Smokes of mosquito coils are used daily to control mosquitoes during summer season in subtropical and tropical countries. So, the aim of this study was to evaluate the effect mosquito coils smokes on the fine structures of the interalveolar septum of the lung of rat. A prominent effect has been observed in the interalveolar septum of lungs of 25 male rats that were exposed to mosquito-coil smokes with d-allethrin at airborne particles concentration of 1.27 mg/m3, 7 hrs. /day, 7 days/week for 3 months. In addition to another group of air exposure animals as a control group. Marked hypertrophy and proliferation of disorganized type II alveolar cells with apical microvilli were found to contain numerous vacuolated lamellar bodies. The presence of numerous extravasated red blood cells in the interstitial and alveolar spaces indicates that transient separations of cell junctions of endothelial cells of capillaries to get out blood corpuscles and platelets leading to haemorrage and consequently clotting. Increased frequency of alveolar macrophages, in addition to, the presence of neutrophil and plasma cells are characteristics of these inflammatory processes. The interalveolar septum had been increased in thickness due to proliferation of myofibroblasts and a prominent increase in collagen synthesis

Control of mosquito vectors of tropical infectious diseases: (2) pyrethroid susceptibility of Aedes aegypti ( l) collected from different sites in Thailand.

Four strains (SS, BS, A and B) of Aedes aegypti collected from different sites in Bangkok and at different times were examined for their pyrethroid susceptibility. Mosquito coils containing dl, d-T80-allethrin, d, d-T-prallethrin and methoxymethyl-tetrafluorobenzyl tetramethyl-cyclopropanecarboxylate (K-3050) with or without a synergist were tested by the 25 m3 semi-field test method. One strain (SS) was the most susceptible with KT50 values of about < 30 minutes for all mosquito coils, while the other three strains (BS, A and B) were found to be around 10 to 20 times more tolerant to pyrethroids than the SS strain. A similar tendency for the pyrethroid susceptibility of the four strains was obtained with tests by topical application method. In field efficacy tests, mosquito coils with d, d-T-prallethrin 0.20% plus N-(2-ethylhexyl)bicycle-[2,2,1]- hept-5- ene-2,3-dicarboxyimide as a synergist exhibited a repellent effect of about 85%, while those with K-3050 0.10% plus the synergist exhibited a greater repellent effect of about 90%. In contrast, the repellent effect of commercial dl, d-T80-allethrin 0.20% coils was as low as about 50%. The d, d-T-prallethrin and K-3050 coils with the synergist were confirmed to be highly effective in repelling Ae. aegypti.

Vector control in leishmaniasis.

Indoor residual spraying is a simple and cost effective method of controlling endophilic vectors and DDT remains the insecticide of choice for the control of leishmaniasis. However resistance to insecticide is likely to become more widespread in the population especially in those areas in which insecticide has been used for years. In this context use of slow release emulsified suspension (SRES) may be the best substitute. In this review spraying frequencies of DDT and new schedule of spray have been discussed. Role of biological control and environment management in the control of leishmaniasis has been emphasized. Allethrin (coil) 0.1 and 1.6 per cent prallethrin (liquid) have been found to be effective repellents against Phlebotomus argentipes, the vector of Indian kalaazar. Insecticide impregnated bednets is another area which requires further research on priority basis for the control of leishmaniasis. Role of satellite remote sensing for early prediction of disease by identifying the sandflygenic conditions cannot be undermined. In future synthetic pheromons can be exploited in the control of leishmaniasis.

Ultra low volume aerosol application of deltacide (deltamethrin 0.5% w/v, S-bioallethrin 0.71% w/v & piperonyl butoxide 8.9% w/v) against mosquitoes.

BACKGROUND & OBJECTIVE: Insecticide in the form of space spray as an ultra low volume (ULV) aerosol are used during epidemics of vector borne diseases. Deltacide, a formulation comprising of three chemicals viz., deltamethrin 0.5 per cent w/v, S-bio-allethrin 0.71 per cent w/v and piperonyl butoxide 8.9 per cent w/v is suitable for ULV application. As this combination is found to be effective in preventing resistance development tackling the population, which had already developed resistance and cause immediate mortality, its synergistic effect was tested in Peet Grady chamber, against three species of mosquitoes, viz., Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus. METHODS: Blood fed females were exposed to ULV application of deltacide in a Peet Grady chamber at four dosages viz., 0.005, 0.01, 0.02 and 0.04 ml/m2 and examined for knockdown activity at 10 min interval for 60 min. Thereafter, the mosquitoes were removed from the chamber and maintained in another room having controlled temperature (28+/-2 degrees C) and humidity (60-75%) and observed for recovery, if any, and the per cent knockdown was calculated. Mortality rate after 24 h of holding period was also determined from moribund and dead adults. RESULTS: Pairwise comparison showed that the effect of deltacide spray varied significantly (P<0.001) among the three species tested. The effectiveness was significantly higher in Ae. aegypti, when compared with that of Cx. quiquefasciatus (P<0.001) and An. stephensi (P<0.05). However, there was no significant difference in the efficacy of deltacide between Cx. quiquefasciatus and An. stephensi. All species of mosquitoes became inactive i.e., knocked down completely within 60 min of exposure at all the dosages tested and mortality observed was 100 per cent after 24 h of exposure. INTERPRETATION & CONCLUSION: Deltacide when tested in the form of ULV cold aerosol, the dosage 0.01 ml/m2 was effective against both Ae. aegypti, and An. stephensi, and 0.02 ml/m2 against Cx. quiquefasciatus, causing 100 per cent mortality. The efficacy of ULV application of deltacide against vector mosquitoes needs to be assessed under field conditions.

Effect of S-bioallethrin on human lymphocyte / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the effect of the S-bioallethrin on human lymphocytes by microarray technique.</p><p><b>METHODS</b>The changes of normal human lymphocytes treated with S-bioallethrin were examined with light microscope, flow cytometry, electron microscope, DNA ladder and microarray techniques.</p><p><b>RESULTS</b>Morphological study showed that the lymphocytes underwent apoptosis after S-bioallethrin exposure, which as further confirmed by the expression changes of 346 genes.</p><p><b>CONCLUSION</b>S-bioallethrin can induce apoptosis of normal human lymphocytes and changes in their gene expression profiles.</p>

Bioefficacy of mosquito mat, coil and dispenser formulations containing allethrin group of synthetic pyrethroids against mosquito vectors.

The bioefficacy of mats, coils and dispensers containing allethrin group of synthetic pyrethroids was studied against laboratory strains of Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi. Except esbiothrin in the mat formulation which was 100 and 178 times more effective against Cx. quinquefasciatus than against Ae. aegypti and An. stephensi with KT50 of 0.005, 0.5 and 0.89 min. respectively, all the three allethrins in mat or coil formulations were equally effective against the three vector mosquitoes. When compared to mat formulations of d-allethrin and bioallethrin, mat formulation of esbiothrin was 156 and 144 times more effective against Cx. quinquefasciatus. It was 162 times more effective against Cx. quinquefasciatus than in the coil formulation. Dispenser containing d-allethrin was the least effective against Cx. quinquefasciatus (KT50: 2.65 min.) and Ae. aegypti (KT50: 4.68 min.) but as effective as coil against An. stephensi. When mat and dispenser heated or coil burnt continuously for 10 hours the knockdown was consistently above 60% in all the three vector species but mortality was not consistently > 60% in Ae. aegypti. Repellent effect of the formulations ranged from 0.0 to 80.3%, 0 to 57.3% and 59.2 to 78.3% against Cx. quinquefasciatus Ae. aegypti and An. stephensi respectively. Repellency was more against An. stephensi than against the other two species. Mats and coils deterred > 50% of the mosquitoes from feeding on the chicken (range: 50 to 99.52%) but in case of dispenser the effect was only 14.72 to 65.01%. The use of these formulations as a control tools in reducing man-vector contact is discussed.

Vapour toxicity of aerosol formulation, allethrin on Culex quinquefasciatus (Diptera: Culicidae), Say & Musca domestica (Diptera: Muscidae) N.

Studies on the toxicity of aerosol vaporizer formulation, allethrin were carried out on both male and female species of C. quinquefasciatus and M. domestica at different times of exposure. ANOVA models revealed significant differences in the mean values of the percentage mortalities in relation to sex and time-of-exposure for both the species.

Evaluation of EMD vaporizers and bioallethrin vaporizing mats against mosquito vectors.

Different Electric-Mat-Device (EMD) vaporizers and bioallethrin impregnated mats were evaluated for the knockdown and mortality in the adults of Culex quinquefasciatus, Anopheles stephensi and Aedes aegypti. Percentage knockdown of 80-100 was recorded throughout the test period of 11 hours. However, the percentage mortality observed was not appreciable in all types of EMD vaporizers. Device "A" was found to be effective only against Ae. aegypti. Devices "C" and "D" showed moderate effects against An. stephensi and Ae. aegypti. Only device "B" was found to give appreciable mortality in all three vector mosquito species compared to other devices which may be attributed to the uniform release rate (2 mg/hour) of bioallethrin.

A field trial on the comparative effectiveness of malathion and Resigen by ULV application on Aedes aegypti.

Field trials were conducted in two residential areas of Petaling Jaya Municipality to test the adulticidal and larvicidal effects of malathion 96% TG and Resigen on Aedes aegypti. Malathion is the currently used insecticide in Malaysia for the control of dengue. The Leco HD ULV machine was used throught the trials. For malathion the flow rate was 90 ml/minute at a vehicle speed of 8kph and for Resigen the flow rate was 200 ml/minute at the same vechicle speed. Malathion was more effective giving higher mortality rates when compared with Resigen. The mortality rate of adult Ae. aegypti outdoor was higher than in the living room and kitchen. Both insecticides did not show promising larvicidal effects.

Field efficacy of mosquito coil formulations containing d-allethrin and d-transallethrin against indoor mosquitos especially Culex quinquefasciatus Say.

Comparative field efficacy studies of four mosquito coil formulations containing active ingredient of d-allethrin (0.19 or 0.28 w/w) and d-transallethrin (0.12 or 0.16% w/w) and blank coils without active ingredient were carried out in living rooms (mean size 54.1 m3) of residential houses in a squatter area in Butterworth, Malaysia. The major indoor biting mosquitos collected in the test site were that of Culex quinquefasciatus Say (84.7%). Mean percentage reduction of blank coils, coils with 0.19 and 0.28% d-allethrin and coils with 0.12 and 0.16% d-transallethrin were 29.0, 71.7, 70.9, 75.0 and 72.6%, respectively. The use of coils as a mean of personal protection against mosquitos is discussed.