Molecular xenomonitoring (MX) and transmission assessment survey (TAS) of lymphatic filariasis elimination in two villages, Menoufyia Governorate, Egypt

Abstract

Lymphatic filariasis (LF) is focally endemic in Egypt where the female mosquito, Culex pipiens, is responsible for its transmission. The aim of the study was to investigate the impact of implementation of the 13th round of MDA in two Egyptian villages in the Menoufyia Governorate area after failing the transmission assessment survey (TAS) in 2005 using two methods, and to decide whether it is safe to stop MDA in these, as well as in similar implementation units (IUs). To achieve this aim, both the immunochromatographic card test (ICT) and molecular xenomonitoring (MX) techniques were employed. A cross-sectional study was carried out in the villages in 2014 with two sections: Section (1): a school-based survey where all the primary school entrants (6-7) years of age were tested by ICT. Section (2): a mosquito-based survey where a total of 152 mosquito pools collected from Samalay and 167 from Kafr El-Tarainah were tested for the presence of the gDNA of Wuchereria bancrofti microfilaria by real-time PCR assays. The results revealed that all primary school children in both villages were 100% negative for antigenemia. Also, all mosquito pools were 100% negative for the microfilarial gDNA.

Molecular xenomonitoring as a post-MDA surveillance tool for global programme to eliminate lymphatic filariasis: Field validation in an evaluation unit in India

“…MX technique is shown to be more efficient and sensitive in detecting parasite DNA than Mf-testing in humans [26,31] and assessing the residual or renewed foci of infection after several rounds of MDA [8,12,19,21,26,[31][32][33][34][35]. LF endemic countries confirmed or supported the findings of TAS with MX on the basis of the absence of transmission during post-MDA or validation phases [19][20][21]25]. Despite a number of studies which compared the decisions of TAS with those of MX, application of MX in operational settings requires an assessment of cost in relation to TAS and feasibility in terms of availability of adequate laboratory facilities and specially trained personnel [26].…”

“…MX involves collection of a large number of vector mosquitoes using appropriate collection methods, sampling techniques to obtain representative sample and detecting parasite DNA in pools of mosquitoes using PCR. Various collection methods have been employed and tested for their efficiency to capture different vector species: gravid traps [8,19,[23][24][25][26][27], CDC light traps and battery powered aspirators for Cx. quinquefasciatus [28], AGT, a variant of OviART & pyrethrum spray method for Anopheles gambiae [13,29,30], and BG sentinel traps for Aedes polynesiensis [12].…”

A systematic review of alternative surveillance approaches for lymphatic filariasis in low prevalence settings: Implications for post-validation settings

“…It also means that results are not truly indicative of PLOS NEGLECTED TROPICAL DISEASES current infectivity and will therefore include cases of historical disease. By contrast, mosquito surveillance gives a snapshot indication of current infection, and could serve as a useful adjunct to human surveillance methods [27,47]. However, mosquito surveillance requires entomology and laboratory capacity, which are both costly and time-consuming, meaning that it is typically only used in very defined areas, rather than for population-wide surveillance [27,45].…”

Assessment of MALDI-TOF mass spectrometry for filariae detection in Aedes aegypti mosquitoes

“…In fact, mosquito dissection is considered the gold standard for measuring infection rates and densities in the vector [ 14 ]. However, this is a labor-intensive and time-consuming procedure requiring entomological expertise [ 15 , 16 ]. Molecular methods such as PCR and gene sequencing have been developed as a tool for detecting filarioid parasite DNA in mosquitoes.…”