Ecological Meta-Analysis of Density-Dependent Processes in the Transmission of Lymphatic Filariasis: Survival of Infected Vectors

Michael, E., Snow, L. C. and Bockarie, Moses (2009) 'Ecological Meta-Analysis of Density-Dependent Processes in the Transmission of Lymphatic Filariasis: Survival of Infected Vectors'. Journal of Medical Entomology, Vol 46, Issue 4, pp. 873-880.

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Abstract

The survival rate of infected vectors represents one of the fundamental components that influence the transmission dynamics of mosquito-borne diseases. Despite the occurrence of a number of studies investigating Mosquito survival after infection with filarial worms, there remains conflicting evidence from both laboratory and field experiments as to the existence and mechanism for parasite-induced mortality among filarial mosquitoes, Here, we used a mixed effects meta-analytical framework to combine the data front all available vector-human host blood feeding experiments to evaluate, the evidence for the impact of parasite load oil the mortality rates of the three major lymphatic filariasis transmitting mosquito genera, Culex, Aedes, and Anopheles mosquitoes, over the extrinsic incubation period of parasitic infection. The results slow that, despite the application of this approach, or in the case of Anopheles using a convention fixed effects logistic regression analysis supplemented with additional survival analysis of longitudinal data, no strong association between mortality rate and microfilariae (mf) uptake for either of the three mosquito genera is apparent in the combined data. Instead, a key finding is that study effects played a more crucial role in determining the levels of mortality observed in these experimental studies. This was most revealing in the case of Cidex, given that the largest single study in terms of both the number of data points and range of mf intensities, in contrast to smaller studies, showed a significant positive association between mf intensity and mortality, indicating that in this genus at least, the detrimental effect of infection may be manifested only at the highest mf intakes. Although no density dependence in vector mortality was also observed for Aedes, possibly because of the use of restricted human mf intensity range in previous studies, all intriguing finding was that a significantly higher overall mortality was observed for this genus over mf intake ranges that produced much less corresponding mortality in Culex and Anopheles. The results also indicate that currently very little can be said about the survival rate of Anopheles mosquitoes infected with filarial worms because of the striking paucity of data for this genus. Further studies, using standardized methods and covering an appropriate range of mf uptake intensities and using study frameworks that allow the design and comparison of data from both experimental and field experiments, are clearly indicated if we are to reliably quantify the likely effect of filarial infection on vector survival.

Item Type:	Article
Uncontrolled Keywords:	Wuchereria bancrofti, lymphatic filariasis, vector survival, ecological meta-analysis
Subjects:	WC Communicable Diseases > Tropical and Parasitic Diseases > WC 880 Filariasis and related conditions (General) QX Parasitology > Insects. Other Parasites > QX 510 Mosquitoes
Faculty: Department:	Groups (2002 - 2012) > Disease Control Strategy Group
Digital Object Identifer (DOI):	https://doi.org/10.1603/033.046.0420
Depositing User:	Users 67 not found.
Date Deposited:	05 Jul 2010 09:46
Last Modified:	06 Feb 2018 12:59
URI:	https://archive.lstmed.ac.uk/id/eprint/327

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