Studies on filariasis. III.<i>Dirofilaria immitis</i>: emergence of infective larvae from the mouthparts of<i>Aedes aegypti</i>

McGreevy, P. B.; Theis, Jerold H.; Lavoipierre, M. M. J.; Clark, J.

doi:10.1017/s0022149x00022896

Cited by 31 publications

(15 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In their respective sites of development, the parasites undergo two larval molts, ultimately developing into infectious third-stage larvae over a period of ∼2 wk. Larvae then migrate to the labial sheath of the mosquito proboscis, where heat and other factors encountered during blood feeding stimulate these transmission-stage larvae to emerge from the labellum, located at the extreme tip of the labium (4,5). Larvae are deposited on the skin in a drop of hemolymph and can enter the vertebrate host through the bite wound, completing the infection cycle (5).…”

mentioning

confidence: 99%

Activation of mosquito immunity blocks the development of transmission-stage filarial nematodes

Edgerton

Mccrea

Berry

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Mosquito-borne helminth infections are responsible for a significant worldwide disease burden in both humans and animals. Accordingly, development of novel strategies to reduce disease transmission by targeting these pathogens in the vector are of paramount importance. We found that a strain of Aedes aegypti that is refractory to infection by Dirofilaria immitis, the agent of canine heartworm disease, mounts a stronger immune response during infection than does a susceptible strain. Moreover, activation of the Toll immune signaling pathway in the susceptible strain arrests larval development of the parasite, thereby decreasing the number of transmission-stage larvae. Notably, this strategy also blocks transmission-stage Brugia malayi, an agent of human lymphatic filariasis. Our data show that mosquito immunity can play a pivotal role in restricting filarial nematode development and suggest that genetically engineering mosquitoes with enhanced immunity will help reduce pathogen transmission.

show abstract

mentioning

confidence: 99%

Activation of mosquito immunity blocks the development of transmission-stage filarial nematodes

Edgerton

Mccrea

Berry

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…This fact can be compared with the similar apparent paradox concerning Culex pipiens fatigans and Wuchereria bancrofti in Rangoon, 62 where there were a large number of infected mosquitoes with a high biting rate, but few people actually became infected, with positive skin tests but without microfilariaemia. While waiting for molecular biology to throw further light on the problem, we can only suggest that the difference between the Old World human pulmonary cases and the Western hemisphere might be explained by two different hypotheses: (i) there are perhaps twin populations of D. immitis with different genotypes on the two sides of the Atlantic, with different infective capacity for man and dog; (ii) the infective capacity to humans of the parasite could be modified only in the Old World by some unidentified factor, possibly inherent to the vector, that affects the complex vector–parasite relationship, 63,64 decreasing the survival of the larvae.…”

Section: Discussionmentioning

confidence: 99%

Dirofilarial human cases in the Old World, attributed to Dirofilaria immitis : a critical analysis

2009

View full text Add to dashboard Cite

On the basis of these analyses we conclude that there is as yet no proof demonstrating with certainty that Old World D. immitis plays a pathogenic role in humans. It remains to be explained why D. immitis causes pulmonary infections in humans in the Americas while, in the Old World, this location appears, instead, to be always associated with D.repens, even though the former species is at times more frequent than the latter both in dogs and in the vectors. To explain this apparently different pathogenic power, two hypotheses are proposed: (i) there are perhaps twin populations with different genotypes on the two sides of the Atlantic, with different infective capacity for man and dog; (ii) the infective capacity to humans of the parasite could be modified, only in the Old World, by some unidentified factor, possibly inherent to the vector, that affects the complex mechanism of the vector-parasite relationship, affecting the survival of the larvae.

show abstract

“…Infective third-stage larvae emerge most typically from the mosquito labellum but can also emerge from the labial sheath during blood feeding (Fig. 1) [5]. Larvae emerging from the mosquito are deposited on the skin in a drop of hemolymph where they can enter the skin through the bite site [5].…”

Section: Introductionmentioning

confidence: 99%

A novel assay to isolate and quantify third-stage filarial larvae emerging from individual mosquitoes

Mccrea

Edgerton

et al. 2020

Preprint

View full text Add to dashboard Cite

Liverpool strain (LVP, refractory, Ae. aegypti R ), microfilariae (mf), Malpighian tubules (MT), third-stage larvae (L3), emerging third-stage larvae (eL3). AbstractMosquitoes transmit filarial nematodes to both human and animal hosts, resulting in worldwide health and economic consequences. Transmission to a vertebrate host requires that ingested microfilariae develop into infective third-stage larvae capable of emerging from the mosquito proboscis onto the skin of the host during blood feeding. An inability to determine what proportion of third-stage larvae are capable of emerging from the mosquito has hindered efforts to assess the efficacy of experimental transmission-blocking strategies and to evaluate the transmission competence of field vectors. To overcome this hurdle, we have developed a novel method to assess the infective third-stage larvae of Dirofilaria immitis that emerge from individual Aedes aegypti and Ae. albopictus mosquitoes. This method does not require specialized equipment, making it amenable for field work. Using this assay, we have determined the proportion of microfilariae that successfully develop into emerging third-stage larvae as well as the fate of those that do not. We have found that once D. immitis third-stage larvae emerge at 13 days post infection, the proportion of mosquitoes producing them, and the number produced per mosquito remain stable until at least day 21. However, during this time, the fitness cost of the infection to the mosquito increases, suggesting that larvae continue to either damage the vector, compete for essential nutrients, or produce toxic metabolites. Increasing uptake of D. immitis microfilariae increases the fitness cost to the mosquito but does not increase the number of emerging third-stage larvae. Notably, we find that our assay is also suitable for assessment of emerging thirdstage larvae of Brugia malayi, one of the filarial nematodes responsible for human lymphatic filariasis.Thus, it is likely that this assay will be applicable to all mosquito-transmitted filariae and possibly filariae transmitted by other hematophagous arthropods. Together, our results indicate that this new assay will facilitate assessment of the transmission potential of arthropod vectors and promote preparation of uniformly infectious L3 for challenge experiments and other functional assays. It will also facilitate analyses of molecular interactions between vectors and filariae, ultimately allowing for the establishment of novel methods to block disease transmission.

show abstract

Studies on filariasis. III.Dirofilaria immitis: emergence of infective larvae from the mouthparts ofAedes aegypti

Cited by 31 publications

References 22 publications

Activation of mosquito immunity blocks the development of transmission-stage filarial nematodes

Activation of mosquito immunity blocks the development of transmission-stage filarial nematodes

Dirofilarial human cases in the Old World, attributed to Dirofilaria immitis : a critical analysis

A novel assay to isolate and quantify third-stage filarial larvae emerging from individual mosquitoes

Contact Info

Product

Resources

About