A physiological time analysis of the duration of the gonotrophic cycle of Anopheles pseudopunctipennis and its implications for malaria transmission in Bolivia

<p>Abstract</p> <p>Background</p> <p>The length of the gonotrophic cycle varies the vectorial capacity of a mosquito vector and therefore its exact estimation is important in epidemiological modelling. Because the gonotrophic cycle length depends on temperature, its estimation can be satisfactorily computed by means of physiological time analysis.</p> <p>Methods</p> <p>A model of physiological time was developed and calibrated for <it>Anopheles pseudopunctipennis</it>, one of the main malaria vectors in South America, using data from laboratory temperature controlled experiments. The model was validated under varying temperatures and could predict the time elapsed from blood engorgement to oviposition according to the temperature.</p> <p>Results</p> <p>In laboratory experiments, a batch of <it>An. pseudopunctipennis </it>fed at the same time may lay eggs during several consecutive nights (2–3 at high temperature and > 10 at low temperature). The model took into account such pattern and was used to predict the range of the gonotrophic cycle duration of <it>An. pseudopunctipennis </it>in four characteristic sites of Bolivia. It showed that the predicted cycle duration for <it>An. pseudopunctipennis </it>exhibited a seasonal pattern, with higher variances where climatic conditions were less stable. Predicted mean values of the (minimum) duration ranged from 3.3 days up to > 10 days, depending on the season and the geographical location. The analysis of ovaries development stages of field collected biting mosquitoes indicated that the phase 1 of Beklemishev might be of significant duration for <it>An. pseudopunctipennis</it>. The gonotrophic cycle length of <it>An. pseudopunctipennis </it>correlates with malaria transmission patterns observed in Bolivia which depend on locations and seasons.</p> <p>Conclusion</p> <p>A new presentation of cycle length results taking into account the number of ovipositing nights and the proportion of mosquitoes laying eggs is suggested. The present approach using physiological time analysis might serve as an outline to other similar studies and allows the inclusion of temperature effects on the gonotrophic cycle in transmission models. However, to better explore the effects of temperature on malaria transmission, the others parameters of the vectorial capacity should be included in the analysis and modelled accordingly.</p

Ambient temperature effects on the extrinsic incubation period of Wuchereria bancrofti in Aedes polynesiensis : implications for filariasis transmission dynamics and distribution in French Polynesia

Temperature effects on development of the human filarial parasite #Wuchereria bancrofti (Cobbold) (Filaridea : Onchocercidae) in the main Pacific vector #Aedes polynesiensis Marks (Diptera : Culicidae) are analysed in relation to ambient climatic conditions. A statistical model of the extrinsic cycle duration as a function of temperature is described and used to distinguish three patterns of #W. bancrofti transmission dynamics : continuous, fluctuating and discontinuous, occurring from north to south geographically among French Polynesian archipelagos. In the northerly Marquesas Islands (8-11° S) filariasis transmission is continuous and very active, facilitated by perennially high temperatures combined with constantly high rates of man-vector contact. In the southerly Australes Islands (21-28° S) filariasis transmission is seasonally discontinuous and, during the cooler months (May-September), the model predicts virtually no transmission because the cycle duration exceeds the life expectancy of the vector. In the Society Islands (16-18° S), between the Marquesas and Australes, transmission is predicted to be intermediate as expected from their latitude, with seasonally fluctuating transmission potential. In the Tuamotu Islands (also geographically intermediate : 14-23° S), with theoretically perennial transmission potential, transmission occurs only intermittently, being limited by other human and environmental factors whereby man-vector contact is confined to seasonal agricultural situations. Generally, among French Polynesian archipelagos where #Aedes polynesiensis is the vector, the transmission potential for #W. bancrofti$ and resulting disease manifestations of lymphatic filariasis in humans are correlated with ambient temperature due to the degree of southern latitude. (Résumé d'auteur

Ambient temperature effects on the extrinsic incubation period of Wuchereria bancrofti in Aedes polynesiensis : implications for filariasis transmission dynamics and distribution in French Polynesia

Temperature effects on development of the human filarial parasite #Wuchereria bancrofti (Cobbold) (Filaridea : Onchocercidae) in the main Pacific vector #Aedes polynesiensis Marks (Diptera : Culicidae) are analysed in relation to ambient climatic conditions. A statistical model of the extrinsic cycle duration as a function of temperature is described and used to distinguish three patterns of #W. bancrofti transmission dynamics : continuous, fluctuating and discontinuous, occurring from north to south geographically among French Polynesian archipelagos. In the northerly Marquesas Islands (8-11° S) filariasis transmission is continuous and very active, facilitated by perennially high temperatures combined with constantly high rates of man-vector contact. In the southerly Australes Islands (21-28° S) filariasis transmission is seasonally discontinuous and, during the cooler months (May-September), the model predicts virtually no transmission because the cycle duration exceeds the life expectancy of the vector. In the Society Islands (16-18° S), between the Marquesas and Australes, transmission is predicted to be intermediate as expected from their latitude, with seasonally fluctuating transmission potential. In the Tuamotu Islands (also geographically intermediate : 14-23° S), with theoretically perennial transmission potential, transmission occurs only intermittently, being limited by other human and environmental factors whereby man-vector contact is confined to seasonal agricultural situations. Generally, among French Polynesian archipelagos where #Aedes polynesiensis is the vector, the transmission potential for #W. bancrofti$ and resulting disease manifestations of lymphatic filariasis in humans are correlated with ambient temperature due to the degree of southern latitude. (Résumé d'auteur

A physiological time analysis of the duration of the gonotrophic cycle of and its implications for malaria transmission in Bolivia-3

<p><b>Copyright information:</b></p><p>Taken from "A physiological time analysis of the duration of the gonotrophic cycle of and its implications for malaria transmission in Bolivia"</p><p>http://www.malariajournal.com/content/7/1/141</p><p>Malaria Journal 2008;7():141-141.</p><p>Published online 26 Jul 2008</p><p>PMCID:PMC2518372.</p><p></p

A physiological time analysis of the duration of the gonotrophic cycle of and its implications for malaria transmission in Bolivia-1

February 2003. Cycle duration is in days.<p><b>Copyright information:</b></p><p>Taken from "A physiological time analysis of the duration of the gonotrophic cycle of and its implications for malaria transmission in Bolivia"</p><p>http://www.malariajournal.com/content/7/1/141</p><p>Malaria Journal 2008;7():141-141.</p><p>Published online 26 Jul 2008</p><p>PMCID:PMC2518372.</p><p></p

A physiological time analysis of the duration of the gonotrophic cycle of and its implications for malaria transmission in Bolivia-0

<p><b>Copyright information:</b></p><p>Taken from "A physiological time analysis of the duration of the gonotrophic cycle of and its implications for malaria transmission in Bolivia"</p><p>http://www.malariajournal.com/content/7/1/141</p><p>Malaria Journal 2008;7():141-141.</p><p>Published online 26 Jul 2008</p><p>PMCID:PMC2518372.</p><p></p

A physiological time analysis of the duration of the gonotrophic cycle of and its implications for malaria transmission in Bolivia-2

E comparison), from January 1998 to December 2000. Cycle durations are in days.<p><b>Copyright information:</b></p><p>Taken from "A physiological time analysis of the duration of the gonotrophic cycle of and its implications for malaria transmission in Bolivia"</p><p>http://www.malariajournal.com/content/7/1/141</p><p>Malaria Journal 2008;7():141-141.</p><p>Published online 26 Jul 2008</p><p>PMCID:PMC2518372.</p><p></p