Development of Leishmania (Leishmania) infantum chagasi in Its Natural Sandfly Vector Lutzomyia longipalpis

Freitas, Vanessa Cabreira de; Parreiras, Klívia P.; Duarte, Ana Paula; Secundino, Nágila F. C.; Pimenta, Paulo Filemon Paolucci

doi:10.4269/ajtmh.2012.11-0386

Cited by 26 publications

(26 citation statements)

References 48 publications

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“…Accordingly, our experiments with L. donovani showed similar numbers of metacyclic forms in mature infections as well as comparable transmission efficiency in amastigote- and promastigote-initiated P. argentipes infections. Different results were reported with late stage infections of L. infantum chagasi in L. longipalpis (Freitas et al 2012). Here metacyclics were 10 times less represented in amastigote-initiated infections compare to promastigote-initiated infection.…”

Section: Discussionmentioning

confidence: 84%

“…Direct comparisons between these two methods are scarce and effects of this factor on transmission potential have not been compared. There is only a single similar study on Leishmania infantum–Lutzomyia longipalpis parasite–vector model (Freitas et al 2012) which was, however, performed using axenic amastigotes that may substantially differ from intracellular ones due to the loss of important factors during a long-term in vitro culture (Pescher et al 2011). Here we compared Leishmania donovani infection in its natural vector Phlebotomus argentipes using culture form promastigotes and amastigotes grown ex vivo in bone marrow-derived macrophages (BMM).…”

Section: Introductionmentioning

confidence: 99%

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Leishmania donovani development in Phlebotomus argentipes: comparison of promastigote- and amastigote-initiated infections

et al. 2016

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SUMMARYLeishmania parasites alternate in their life cycle between promastigote stages that develop in the gut of phlebotomine sand flies and amastigotes residing inside phagocytic cells of vertebrate hosts. For experimental infections of sand flies, promastigotes are frequently used as this way of infection is technically easier although ingestion of promastigotes by sand flies is unnatural. Here we aimed to answer a critical question, to what extent do promastigote-initiated experimental infections differ from those initiated with intracellular amastigotes. We performed side-by-side comparison of Leishmania development in Phlebotomus argentipes females infected alternatively with promastigotes from log-phase cultures or amastigotes grown ex vivo in macrophages. Early stage infections showed substantial differences in parasite load and representation of morphological forms. The differences disappeared along the maturation of infections; both groups developed heavy late-stage infections with colonization of the stomodeal valve, uniform representation of infective metacyclics and equal efficiency of transmission. The results showed that studies focusing on early phase of Leishmania development in sand flies should be initiated with intracellular amastigotes. However, the use of promastigote stages for sand fly infections does not alter significantly the final outcome of Leishmania donovani development in P. argentipes and their transmissibility to the vertebrate host.

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Section: Discussionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Leishmania donovani development in Phlebotomus argentipes: comparison of promastigote- and amastigote-initiated infections

et al. 2016

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“…In this study, we discriminated between infected vectors (vectors with viable parasites in their gut) and uninfected ones. However, infected vectors may have different infectiousness levels [15] , [40] . Thus, although a reduction in the 3.2% most infected hosts will decrease the total number of infected vectors, and consequently, reduce the R 0 , EIR, and morbidity, quantifying the success of such a control strategy necessitates the development of a dynamic model that involves data on the vector population dynamics and the distribution of the their levels of infectiousness.…”

Section: Discussionmentioning

confidence: 99%

“…Indeed, the number of Leishmania parasites at the initial stages of the sand fly infection is usually very low (e.g., between 1–500), while sand flies with mature infection frequently harbor tens of thousands of parasites [14] , [15] , [16] . Once the infection in the vector gut has been established through this density-independent process, the progression (that may be density-dependent due to intraspecific competition) to mature transmissible infection, is thought to be almost definite [14] , [15] , [16] . Thus, the probability that the j parasites in equation (1) will infect the vector, s ( j ), is given by: …”

Section: Methodsmentioning

confidence: 99%

Quantifying the Contribution of Hosts with Different Parasite Concentrations to the Transmission of Visceral Leishmaniasis in Ethiopia

et al. 2014

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BackgroundAn important factor influencing the transmission dynamics of vector-borne diseases is the contribution of hosts with different parasitemia (no. of parasites per ml of blood) to the infected vector population. Today, estimation of this contribution is often impractical since it relies exclusively on limited-scale xenodiagnostic or artificial feeding experiments (i.e., measuring the proportion of vectors that become infected after feeding on infected blood/host).MethodologyWe developed a novel mechanistic model that facilitates the quantification of the contribution of hosts with different parasitemias to the infection of the vectors from data on the distribution of these parasitemias within the host population. We applied the model to an ample data set of Leishmania donovani carriers, the causative agent of visceral leishmaniasis in Ethiopia.ResultsCalculations facilitated by the model quantified the host parasitemias that are mostly responsible for the infection of vector, the sand fly Phlebotomus orientalis. Our findings indicate that a 3.2% of the most infected people were responsible for the infection of between 53% and 79% (mean – 62%) of the infected sand fly vector population.SignificanceOur modeling framework can easily be extended to facilitate the calculation of the contribution of other host groups (such as different host species, hosts with different ages) to the infected vector population. Identifying the hosts that contribute most towards infection of the vectors is crucial for understanding the transmission dynamics, and planning targeted intervention policy of visceral leishmaniasis as well as other vector borne infectious diseases (e.g., West Nile Fever).

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“…This finding suggests extremely high susceptibility of P. orientalis for L. donovani ; at present, the similar study using amastigotes is underway in our laboratory. Due to technical difficulties similar studies using amastigotes have not been performed yet in P. orientalis , however, in L. longipalpis Freitas et al [33] demonstrated that promastigote-initiated L. infantum infections are fully comparable to amastigote-initiated ones.…”

Section: Discussionmentioning

confidence: 99%

Phlebotomus orientalis Sand Flies from Two Geographically Distant Ethiopian Localities: Biology, Genetic Analyses and Susceptibility to Leishmania donovani

et al. 2013

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Background Phlebotomus orientalis Parrot (Diptera: Psychodidae) is the main vector of visceral leishmaniasis (VL) caused by Leishmania donovani in East Africa. Here we report on life cycle parameters and susceptibility to L. donovani of two P. orientalis colonies originating from different sites in Ethiopia: a non-endemic site in the lowlands - Melka Werer (MW), and an endemic focus of human VL in the highlands - Addis Zemen (AZ).Methodology/Principal FindingsMarked differences in life-cycle parameters between the two colonies included distinct requirements for larval food and humidity during pupation. However, analyses using Random Amplified Polymorphic DNA (RAPD) PCR and DNA sequencing of cytB and COI mitochondrial genes did not reveal any genetic differences. F1 hybrids developed successfully with higher fecundity than the parental colonies. Susceptibility of P. orientalis to L. donovani was studied by experimental infections. Even the lowest infective dose tested (2×103 per ml) was sufficient for successful establishment of L. donovani infections in about 50% of the P. orientalis females. Using higher infective doses, the infection rates were around 90% for both colonies. Leishmania development in P. orientalis was fast, the presence of metacyclic promastigotes in the thoracic midgut and the colonization of the stomodeal valve by haptomonads were recorded in most P. orientalis females by day five post-blood feeding.ConclusionsBoth MW and AZ colonies of P. orientalis were highly susceptible to Ethiopian L. donovani strains. As the average volume of blood-meals taken by P. orientalis females are about 0.7 µl, the infective dose at the lowest concentration was one or two L. donovani promastigotes per sand fly blood-meal. The development of L. donovani was similar in both P. orientalis colonies; hence, the absence of visceral leishmaniasis in non-endemic area Melka Werer cannot be attributed to different susceptibility of local P. orientalis populations to L. donovani.

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Development of Leishmania (Leishmania) infantum chagasi in Its Natural Sandfly Vector Lutzomyia longipalpis

Cited by 26 publications

References 48 publications

Leishmania donovani development in Phlebotomus argentipes: comparison of promastigote- and amastigote-initiated infections

Leishmania donovani development in Phlebotomus argentipes: comparison of promastigote- and amastigote-initiated infections

Quantifying the Contribution of Hosts with Different Parasite Concentrations to the Transmission of Visceral Leishmaniasis in Ethiopia

Phlebotomus orientalis Sand Flies from Two Geographically Distant Ethiopian Localities: Biology, Genetic Analyses and Susceptibility to Leishmania donovani

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