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. 2023 Jan 19;22(1):22.
doi: 10.1186/s12936-022-04435-9.

Transmission efficiency of Plasmodium vivax at low parasitaemia

Thitiporn Surit  1   2 , Piyarat Sripoorote  1 , Chalermpon Kumpitak  1 , Chayanut Suansomjit  1 , Nongnuj Maneechai  1 , Liwang Cui  3 , Jetsumon Sattabongkot  1 , Wanlapa Roobsoong  4 , Wang Nguitragool  5   6
Affiliations

Transmission efficiency of Plasmodium vivax at low parasitaemia

Thitiporn Surit et al. Malar J. .

Abstract

Background: Plasmodium vivax is responsible for much of malaria outside Africa. Although most P. vivax infections in endemic areas are asymptomatic and have low parasite densities, they are considered a potentially important source of transmission. Several studies have demonstrated that asymptomatic P. vivax carriers can transmit the parasite to mosquitoes, but the efficiency has not been well quantified. The aim of this study is to determine the relationship between parasite density and mosquito infectivity, particularly at low parasitaemia.

Methods: Membrane feeding assays were performed using serial dilutions of P. vivax-infected blood to define the relationship between parasitaemia and mosquito infectivity.

Results: The infection rate (oocyst prevalence) and intensity (oocyst load) were positively correlated with the parasite density in the blood. There was a broad case-to-case variation in parasite infectivity. The geometric mean parasite density yielding a 10% mosquito infection rate was 33 (CI 95 9-120) parasites/µl or 4 (CI 95 1-17) gametocytes/µl. The geometric mean parasite density yielding a 50% mosquito infection rate was 146 (CI 95 36-586) parasites/µl or 13 (CI 95 3-49) gametocytes/µl.

Conclusion: This study quantified the ability of P. vivax to infect Anopheles dirus at over a broad range of parasite densities. It provides important information about parasite infectivity at low parasitaemia common among asymptomatic P. vivax carriers.

Keywords: Anopheles; Asymptomatic; Gametocyte; Infectivity; Malaria; Oocyst; Plasmodium vivax; Transmission.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Plasmodium vivax densities in serially diluted blood samples. Shown are the relationships between actual LM counts and calculated parasite densities based on the dilution factors for a total blood-stage parasites, b total gametocytes, c female gametocytes and d male gametocytes. For each plot, data from all 8 cases were combined. Only data with calculated densities above 3 per microliter were included. Trendlines represent the best linear fits with zero crossing on the log-log scale
Fig. 2
Fig. 2
Mosquito infection as a function of parasite or gametocyte densities. a mosquito infection rate vs. total parasitaemia, b the oocyst intensity vs. total parasitaemia, c mosquito infection rate vs. total gametocytaemia and d the oocyst intensity vs. total gametocytaemia
Fig. 3
Fig. 3
Relationship between oocyst density and mosquito infection rate. Black circles represent values from individual feeding experiments in this study. White circles represent values from individual feeding experiments with AB serum replacement from a previous study [25]. The solid red line is the best fit by Hill’s equation
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References

    1. World malaria report . 20 years of global progress and challenges. Geneva: World Health Organization; 2020.
    1. Lertpiriyasuwat C, Sudathip P, Kitchakarn S, Areechokchai D, Naowarat S, Shah JA, et al. Implementation and success factors from Thailand’s 1–3-7 surveillance strategy for malaria elimination. Malar J. 2021 doi: 10.1186/s12936-021-03740-z. - DOI - PMC - PubMed
    1. Cao J, Sturrock HJ, Cotter C, Zhou S, Zhou H, Liu Y, et al. Communicating and monitoring surveillance and response activities for malaria elimination: China’s “1-3-7” strategy. PLoS Med. 2014;11:e1001642. doi: 10.1371/journal.pmed.1001642. - DOI - PMC - PubMed
    1. Vasquez-Jimenez JM, Arevalo-Herrera M, Henao-Giraldo J, Molina-Gomez K, Arce-Plata M, Vallejo AF, et al. Consistent prevalence of asymptomatic infections in malaria endemic populations in Colombia over time. Malar J. 2016;15:70. doi: 10.1186/s12936-016-1124-x. - DOI - PMC - PubMed
    1. Waltmann A, Darcy AW, Harris I, Koepfli C, Lodo J, Vahi V, et al. High rates of asymptomatic, sub-microscopic Plasmodium vivax infection and disappearing Plasmodium falciparum malaria in an area of low transmission in Solomon Islands. PLoS Negl Trop Dis. 2015;9:e0003758. doi: 10.1371/journal.pntd.0003758. - DOI - PMC - PubMed