Molecular Taxonomy of Anopheles (Nyssorhynchus) benarrochi (Diptera: Culicidae) and Malaria Epidemiology in Southern Amazonian Peru

BackgroundMalaria transmission in the peri-Iquitos region of Amazonian Peru has been designated as seasonal and hypo-endemic with recently described hyper-endemic hotspots. Despite relatively recent distribution of long-lasting insecticidal bed nets (LLINs), malaria in Amazonian Peru persists and increased substantially in 2014 compared to previous years. Anopheles darlingi, identified as the main malaria vector, is known for its variable behaviour depending on locality and environment.MethodsTo evaluate vector biology metrics in relation to seasonality and malaria transmission, mosquito collections were carried out in three localities in the peri-Iquitos region, Loreto, Peru in 2011–2012. Human landing catch (HLC) collection method, Shannon (SHA) and CDC trap types were compared for effectiveness in a neotropical setting. Abundance, human biting rate and entomological inoculation rate (EIR) were measured to provide an updated view of transmission patterns post-LLIN distribution.ResultsHLC collected significantly more anopheline mosquitoes than SHA and CDC light traps. Anopheles darlingi was the most prevalent species in all three villages (84% overall). Biting patterns varied depending on trap type, season and village. EIR varied temporally (monthly) and spatially and the highest (2.52) occurred during the 2012 malaria outbreak in Cahuide. Unexpectedly there was a high infection rate (1.47 and 1.75) outside the normal malaria transmission season, coincident with a second local outbreak in Cahuide. The first identification of Anopheles dunhami and Anopheles oswaldoi C in Peru, using molecular markers, is also reported in this study.ConclusionThese data underscore the importance of HLC as the most meaningful collection method for measuring vector biology indices in this region. The highest monthly EIR provides additional evidence of seasonal transmission in riverine localities correlated with high river levels, and An. darlingi as the only contributor to transmission. The trend of an increase in outdoor-biting together with early-evening infected mosquitoes may undermine the effectiveness of LLINs as a primary malaria intervention.

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“…Anopheles benarrochi B, a member of the An. benarrochi complex, was first reported in Peru recently [ 8 ].…”

Section: Resultsmentioning

confidence: 99%

“…Anopheles darlingi is the main vector in the region although other species, such as Anopheles benarrochi s.l., may be involved in local transmission [ 7 , 8 ]. In the Iquitos area, Andean snowmelt combined with rainfall increases river levels (up to 10 m), resulting in large seasonal fluctuations in anopheline abundance [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

Implications for changes in Anopheles darlingi biting behaviour in three communities in the peri-Iquitos region of Amazonian Peru

Moreno

Saavedra

Bickersmith

et al. 2015

Malar J

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“…benarrochi as a species complex, with the identification of Ny. benarrochi B in Colombia [ 85 ] and Peru [ 86 ]. Although Ny.…”

Section: Discussionmentioning

confidence: 99%

Exploring malaria vector diversity on the Amazon Frontier

Bourke

Conn

Oliveira

et al. 2018

Malar J

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BackgroundDeforestation in the Amazon and the social vulnerability of its settler communities has been associated with increased malaria incidence. The feeding biology of the most important malaria vectors in the region, notably Nyssorhynchus darlingi, compounds efforts to control vectors and reduce transmission of what has become known as “Frontier Malaria”. Exploring Anophelinae mosquito diversity is fundamental to understanding the species responsible for transmission and developing appropriate management and intervention strategies for malaria control in the Amazon River basin.MethodsThis study describes Anophelinae mosquito diversity from settler communities affected by Frontier Malaria in the states of Acre, Amazonas and Rondônia by analysing COI gene data using cluster and tree-based species delimitation approaches.ResultsIn total, 270 specimens from collection sites were sequenced and these were combined with 151 reference (GenBank) sequences in the analysis to assist in species identification. Conservative estimates found that the number of species collected at these sites was between 23 (mPTP partition) and 27 (strict ABGD partition) species, up to 13 of which appeared to be new. Nyssorhynchus triannulatus and Nyssorhynchus braziliensis displayed exceptional levels of intraspecific genetic diversity but there was little to no support for putative species complex status.ConclusionsThis study demonstrates that Anophelinae mosquito diversity continues to be underestimated in poorly sampled areas where frontier malaria is a major public health concern. The findings will help shape future studies of vector incrimination and transmission dynamics in these areas and support efforts to develop more effective vector control and transmission reduction strategies in settler communities in the Amazon River basin.Electronic supplementary materialThe online version of this article (10.1186/s12936-018-2483-2) contains supplementary material, which is available to authorized users.

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“…darlingi , but to date it has proven difficult to identify breeding sites of this mosquito species within environmental contamination and degradation related to human settlements and mining-related chemical discharges in the malaria-affected areas. Anopheles ( Nyssorhynchus ) benarrochi B and Anopheles ( Nyssorhynchus ) rangeli were also found among anopheline specimens obtained and analyzed in 2011 by human landing catch, Shannon and CDC traps (Centers for Disease Control and Prevention, Atlanta, GA) from the malaria endemic localities of Santa Rosa and San Pedro in Madre de Dios Department, Peru; neither of these potential secondary vectors were found to be positive for Plasmodium infection by cytochromb b (CytB)-PCR, although the sample size was relatively small 52. Research findings in Madre de Dios highlight the unpredictable nature of malaria transmission in areas of Peru where public health policies are difficult to implement, and only control measures based on PCD have been carried out.…”

Section: Peruvian P Vivax-endemic Regionsmentioning

confidence: 99%

Epidemiology of Plasmodium vivax Malaria in Peru

Aguirre¹,

Gamboa²,

Manrique³

et al. 2016

Am J Trop Med Hyg

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Malaria in Peru, dominated by Plasmodium vivax, remains a public health problem. The 1990s saw newly epidemic malaria emerge, primarily in the Loreto Department in the Amazon region, including areas near to Iquitos, the capital city, but sporadic malaria transmission also occurred in the 1990s–2000s in both north-coastal Peru and the gold mining regions of southeastern Peru. Although a Global Fund-supported intervention (PAMAFRO, 2005–2010) was temporally associated with a decrease of malaria transmission, from 2012 to the present, both P. vivax and Plasmodium falciparum malaria cases have rapidly increased. The Peruvian Ministry of Health continues to provide artemesinin-based combination therapy for microscopy-confirmed cases of P. falciparum and chloroquine–primaquine for P. vivax. Malaria transmission continues in remote areas nonetheless, where the mobility of humans and parasites facilitates continued reintroduction outside of ongoing surveillance activities, which is critical to address for future malaria control and elimination efforts. Ongoing P. vivax research gaps in Peru include the following: identification of asymptomatic parasitemics, quantification of the contribution of patent and subpatent parasitemics to mosquito transmission, diagnosis of nonparasitemic hypnozoite carriers, and implementation of surveillance for potential emergence of chloroquine- and 8-aminoquinoline-resistant P. vivax. Clinical trials of tafenoquine in Peru have been promising, and glucose-6-phosphate dehydrogenase deficiency in the region has not been observed to be a limitation to its use. Larger-scale challenges for P. vivax (and malaria in general) in Peru include logistical difficulties in accessing remote riverine populations, consequences of government policy and poverty trends, and obtaining international funding for malaria control and elimination.

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Molecular Taxonomy of Anopheles (Nyssorhynchus) benarrochi (Diptera: Culicidae) and Malaria Epidemiology in Southern Amazonian Peru

Cited by 12 publications

References 21 publications

Implications for changes in Anopheles darlingi biting behaviour in three communities in the peri-Iquitos region of Amazonian Peru

Implications for changes in Anopheles darlingi biting behaviour in three communities in the peri-Iquitos region of Amazonian Peru

Exploring malaria vector diversity on the Amazon Frontier

Epidemiology of Plasmodium vivax Malaria in Peru

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