Examining the human infectious reservoir for Plasmodium falciparum malaria in areas of differing transmission intensity

Gonçalves, Bronner P.; Kapulu, Melissa; Sawa, Patrick; Guelbéogo, Wamdaogo Moussa; Tiono, Alfred B.; Grignard, Lynn; Stone, Will; Hellewell, Joel; Lanke, Kjerstin; Bastiaens, Guido J. H.; Bradley, John; Nébié, Issa; Ngoi, Joyce M.; Oriango, Robin; Mkabili, Dora; Nyaurah, Maureen; Midega, Janet; Wirth, Dyann F.; Marsh, Kevin; Churcher, Thomas S.; Bejon, Philip; Sirima, Sodiomon B.; Drakeley, Chris; Bousema, Teun

doi:10.1038/s41467-017-01270-4

Cited by 197 publications

(285 citation statements)

References 38 publications

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“…Notably, similar to results from other studies [9,16,[23][24][25], in our cohort 3 rounds of IRS provided almost total protection against symptomatic malaria, irrespective of age group.…”

Section: Discussionsupporting

confidence: 91%

Persistent Parasitemia Despite Dramatic Reduction in Malaria Incidence After 3 Rounds of Indoor Residual Spraying in Tororo, Uganda

Nankabirwa

Briggs

Rek

et al. 2018

The Journal of Infectious Diseases

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“…Notably, similar to results from other studies [9,16,[23][24][25], in our cohort 3 rounds of IRS provided almost total protection against symptomatic malaria, irrespective of age group.…”

Section: Discussionsupporting

confidence: 91%

Persistent Parasitemia Despite Dramatic Reduction in Malaria Incidence After 3 Rounds of Indoor Residual Spraying in Tororo, Uganda

Nankabirwa

Briggs

Rek

et al. 2018

The Journal of Infectious Diseases

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“…These pathogens primarily circulate and amplify in wild bird reservoir hosts (except RVFV, which primarily circulates in livestock). For all six viruses, humans are dead-end or unimportant reservoir hosts [28,29], in contrast to pathogens like malaria, dengue virus, yellow fever virus, and Ross River virus, which can sustain infection cycles between humans and mosquitoes [28,30,31]. Most transmission of RVFV to humans occurs through direct contact with infected livestock, although it also occurs to a lesser extent via the typical mosquito-borne transmission route, i.e., bites from infected vectors [29].…”

Section: These Temperate Viruses Include: West Nile Virus (Wnv) Stmentioning

confidence: 99%

Transmission of West Nile and other temperate mosquito-borne viruses peaks at intermediate environmental temperatures

Shocket

Verwillow

Numazu

et al. 2019

Preprint

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WORDS)Temperature is a key driver of mosquito-borne disease because it affects the physiology and life history traits of mosquitoes and the pathogens they transmit. These trait thermal responses are typically nonlinear and vary by species. However, the impact of temperature on many important temperate mosquito-borne diseases has never been quantified, and it is unclear if thermal responses of temperate mosquito-borne diseases differ systematically from the patterns found in better-studied tropical systems. These environment-transmission relationships are critical for understanding current seasonal and geographic distributions of disease and future shifts due to climate change. We used a mechanistic, trait-based approach to characterize temperature-dependent transmission of 10 vector-pathogen pairs in an overlapping network of mosquitoes (Culex pipiens, Cx. quinquefascsiatus, Cx. tarsalis, Aedes triseriatus, and others) and viruses (West Nile virus [WNV], Eastern and Western Equine Encephalitis viruses [EEEV and WEEV], St. Louis Encephalitis virus [SLEV], Sindbis virus [SINV], and Rift Valley Fever virus[RVFV]), most of which have predominantly temperate geographic distributions worldwide. We found that several of these temperate pathogens have lower thermal limits (8.6-19.0ºC) and optima (22.7-26.0ºC) that are cooler than those of tropical pathogens (lower thermal limits:16.2-22.8ºC; optima: 25.4-29.1ºC), as expected based on geography. However, their upper thermal limits (31.9-37.8ºC) were very similar to those of tropical pathogens (31.4-34.5ºC).Together, these patterns led to wider thermal breadths (NUMºC) for several of the temperate viruses compared to most tropical pathogens (NUMºC). Among temperate viruses, thermal limits for transmission varied more and were more uncertain than the optima. While the qualitative shapes of trait thermal responses generally matched prior studies, lifespan declined monotonically at temperatures above 14ºC for the temperate Culex vectors, in contrast to 4 unimodal responses observed within this temperature range for tropical species. We validated the mechanistic models with independent data on human disease cases. The incidence of WNV across US counties responded unimodally to temperature and peaked at 23.9ºC, closely matching model predictions (optima for WNV in North American vectors ranged from 23.9-25.2ºC).Additionally, data on the month of onset of cases of WNV, SLEV, and EEEV suggested that temperature is important for determining the seasonality of transmission. The thermal responses for parasite development rate, vector competence, biting rate, and lifespan, all of which varied among species and determined thermal limits in models, are a critical need for future empirical work. Because temperature effects on vector-borne disease transmission are pervasive and nonlinear, and climate regimes are changing rapidly, trait-based models are a key tool for predicting how temperature will affect mosquito-borne disease dynamics. 5

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“…Records published January 2010 -July 2017 were searched, yielding 2136 records. A 6 further two records, unpublished at the time of screening, were also included 19,27 , as were additional 7 data collected through contacting authors of included references. Studies reporting asexual 8 P.falciparum prevalence by microscopy and PCR in the same population were included.…”

Section: Systematic Review Update and Data Extractionmentioning

confidence: 99%

Global & Temporal Patterns of Submicroscopic Plasmodium falciparum Malaria Infection

Whittaker

Slater

Bousema

et al. 2019

Preprint

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Background: Adoption of molecular techniques to detect Plasmodium falciparum infection has revealed many 11 previously undetected (yet transmissible) low-density infections in areas of low malaria transmission. In a world 12 where numerous countries are approaching elimination, additional data from low transmission areas are 13 required to better understand the determinants of submicroscopic infection and their potential relevance in 14 these settings. 15Methods: We updated a systematic review of studies assessing asexual P. falciparum prevalence by microscopy 16 and PCR in the same population. PubMed and Web of Science databases were searched up to July 2017. Bayesian Research in Context:1 Evidence before this study: Cross-sectional studies of malaria prevalence in endemic populations have revealed 2 the widespread presence of infections with parasite densities lower than the threshold of detection by 3 microscopy. Previous systematic reviews of these surveys have highlighted that the fraction of P.falciparum 4 infections missed by microscopy can be substantial (~45% of all infections detected by PCR on average), that 5 submicroscopic infection is more likely in adults than in children (a phenomenon attributed to increased levels 6 of immunity), and that this missed fraction (the "submicroscopic reservoir") is typically highest in areas with low 7 transmission intensity. Although further work is required, a number of studies have also demonstrated the 8 capacity of these submicroscopic, low density infections to infect mosquitoes and therefore contribute to 9 onwards transmission. 10Added value of this study: Although previous studies have found that infections in older, more immune 11 individuals are more likely to be submicroscopic, in lower transmission settings where individuals generally 12 develop less immunity, a larger proportion of infections are also typically submicroscopic. Here we present an 13 updated systematic review to explore this apparent paradox across a range of transmission settings and define 14 contexts in which submicroscopic infections are likely to be most relevant to malaria control efforts. Leveraging 15 the substantial increase in the availability of malaria cross-sectional surveys reporting prevalence by molecular 16 methods, we explore the association of submicroscopic infection with a number of novel factors -these include

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Examining the human infectious reservoir for Plasmodium falciparum malaria in areas of differing transmission intensity

Cited by 197 publications

References 38 publications

Persistent Parasitemia Despite Dramatic Reduction in Malaria Incidence After 3 Rounds of Indoor Residual Spraying in Tororo, Uganda

Persistent Parasitemia Despite Dramatic Reduction in Malaria Incidence After 3 Rounds of Indoor Residual Spraying in Tororo, Uganda

Transmission of West Nile and other temperate mosquito-borne viruses peaks at intermediate environmental temperatures

Global & Temporal Patterns of Submicroscopic Plasmodium falciparum Malaria Infection

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