Epidemiological significance of vector–parasite interactions

C, Dye

doi:10.1017/s0031182000060601

Cited by 43 publications

(21 citation statements)

References 28 publications

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“…However, the C values considered here range from 3.7 to 29.2, in accord with field estimates [33-38, but see [39][40], so if we consider 1/(DH+WN) roughly equivalent to r, then k ranges from 30b to 50b. Even if we consider the b-equivalent values in our model as ranging from 0.1 to 1 (k values from 3 to 50), field estimates span the resulting range of Z 0 values.…”

Section: Discussionsupporting

confidence: 79%

Discrete-Event Simulation Models of Plasmodium falciparum Malaria

1998

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We develop discrete-event simulation models using a single "timeline" variable to represent the Plasmodium falciparum lifecycle in individual hosts and vectors within interacting host and vector populations. Where they are comparable our conclusions regarding the relative importance of vector mortality and the durations of host immunity and parasite development are congruent with those of classic differential-equation models of malaria, epidemiology. However, our results also imply that in regions with intense perennial transmission, the influence of mosquito mortality on malaria prevalence in humans may be rivaled by that of the duration of host infectivity.

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Section: Discussionsupporting

confidence: 79%

Discrete-Event Simulation Models of Plasmodium falciparum Malaria

1998

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“…Life histories and vectorial capacities of phlebotomines may have direct effect on the incidence of leishmaniasis. [19][20][21] In Lutzomyia, vectorial capacity is highly species specific; 8,22,23 thus, it may vary significantly between cryptic species. Furthermore, clinical manifestation of leishmaniasis has also been found to vary between geographic strains.…”

Section: Discussionmentioning

confidence: 99%

Occurrence of sibling species of Lutzomyia longipalpis (Diptera: Psychodidae) in Venezuela: first evidence from reproductively isolated sympatric populations.

Lampo¹,

Torgerson²,

Márquez³

et al. 1999

The American Journal of Tropical Medicine and Hygiene

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Abstract. The delimitation of cryptic species within the main vector of the American visceral leishmaniasis, Lutzomyia longipalpis, remains a topic of controversy. An analysis of genetic variability based on 8 enzymatic loci revealed fixed differences in 2 diagnostic loci, adenylate kinase (Ak) and hexokinase (Hk), between sympatric and allopatric populations at 4 localities in Venezuela. The absence of heterozygotes for these 2 loci within 1 locality indicates, for the first time, the presence of 2 sympatric reproductively isolated populations or cryptic species within L. longipalpis. Significant differences were also detected between these cryptic species in the allele frequencies of glucose-6-phosphate isomerase (Gpi) and malate dehydrogenase, decarboxylating (Me). One species showed mean heterozygosities that ranged between 6.6% and 6.7%, with 1.6-1.9 alleles detected per locus, while the other had mean heterozygosities that ranged from 4.3% to 6.3%, with 1.3-1.6 alleles per locus. Comparisons of isozyme profiles with published data suggests that 1 species is similar to the L. longipalpis described in Colombian and Brazilian populations, whereas the other has not been previously reported.Many investigators have suggested that Lutzomyia longipalpis (Lutz and Neiva), the main vector of visceral leishmaniasis in America, is composed of a complex of cryptic species. The evidence published has been nevertheless controversial. Two forms of L. longipalpis were identified from Brazilian colonies that differed in the presence of dorsolateral pale spots in the third and fourth abdominal tergites. 1 Crossing experiments showed a significant reduction in fertility between sympatric and allopatric strains of both forms, but a few fertile hybrids from both sexes were also produced. 1 Because reduced fertility was also recorded between similar individuals from different geographic regions, it was concluded that further field studies should be carried out before these 2 morphologic forms were assigned to specific taxa. Further studies on the distribution of these 2 forms suggested that 1 is found from Mexico to southern Brazil while the other is restricted from northern Brazil to the border with Paraguay. 2 The structure of L. longipalpis as a complex of distinct reproductively isolated populations became more complex as new data on isozymes became available. High genetic divergence, decreased fertility, and the presence of several diagnostic loci between laboratory strains from Costa Rica, Colombia, and Brazil suggested the presence of at least 3 sibling species. 3 However, the adequacy of laboratory colonies to study genetic divergence across geographic areas remains debatable since colonies can be subjected to a significant reduction of genetic variability due to the loss of infrequent alleles and decreased heterozygosity. 4,5 In fact, the detection from field samples of several loci intermediate between diagnostic loci from Colombian and Brazilian colonies suggested that a high polymorphism could also explain the high g...

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“…Thus, p is estimated by P 1/u , where p is the daily probability of survival, P is the parity rate of Þeld-captured midges, and u is the length of the gonotrophic cycle. Dye (1990) suggested that using the parous rate to determine survivorship works reasonably well when the aim is to measure comparative change in vectorial capacity.…”

Section: Methodsmentioning

confidence: 99%

Seasonal Transmission of Bluetongue Virus by <I>Culicoides sonorensis</I> (Diptera: Ceratopogonidae) at a Southern California Dairy and Evaluation of Vectorial Capacity as a Predictor of Bluetongue Virus Transmission

Gerry¹,

Mullens²,

Maclachlan³

et al. 2001

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Vectorial capacity of Culicoides sonorensis Wirth & Jones for the transmission of bluetongue (BLU) virus was examined at a southern California dairy from January 1995 to December 1997. Insects were collected one to two times per week in five CDC-type suction traps (without light) baited with CO2 at a constant release rate of 1,000 ml/min. BLU virus was detected in midges collected from May through December with an estimated overall infection rate of 0.08%. The BLU virus infection rate of field-captured midges was not correlated with sentinel calf seroconversions to BLU virus. Sentinel calf seroconversions were highly seasonal, occurring from August through November with most calves seroconverting during September and October. Vector competence of field-collected nulliparous flies fed a locally acquired serotype of BLU virus in the laboratory was stable among years (17-23%). Vectorial capacity was strongly correlated with BLU virus transmission (measured by sentinel calf seroconversions) during 1995 and 1996, but not during 1997. Host biting rate estimated for traps nearest to the sentinel calves was the index best correlated with BLU virus transmission for all study years and was most highly correlated with sentinel seroconversions 4 wk later. The utility of vectorial capacity and its component variables is discussed for this system.

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Epidemiological significance of vector–parasite interactions

Cited by 43 publications

References 28 publications

Discrete-Event Simulation Models of Plasmodium falciparum Malaria

Discrete-Event Simulation Models of Plasmodium falciparum Malaria

Occurrence of sibling species of Lutzomyia longipalpis (Diptera: Psychodidae) in Venezuela: first evidence from reproductively isolated sympatric populations.

Seasonal Transmission of Bluetongue Virus by <I>Culicoides sonorensis</I> (Diptera: Ceratopogonidae) at a Southern California Dairy and Evaluation of Vectorial Capacity as a Predictor of Bluetongue Virus Transmission

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