Unexpected detection of Plasmodium vivax and Plasmodium falciparum DNA in asymptomatic blood donors: fact or artifact?

Mendrone, Alfredo; Cerutti, Crispim; Levi, José Eduardo; Boulos, Marcos; Sanchez, Maria Carmen Arroyo; Malafronte, Rosely dos Santos; Santi, Sílvia Maria Di; Odone, Vicente

doi:10.1186/1475-2875-13-336

Cited by 10 publications

(16 citation statements)

References 18 publications

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“…Recently, a cross-sectional study revealed a surprisingly high frequency (5.14%, 57/1,108) of P. falciparum real-time PCR positivity in asymptomatic blood donors living or in close contact with forested regions of the southeastern Brazilian Atlantic forest biome [ 21 ]. The bromeliad-malaria paradigm would predict no P. falciparum infection and very low frequency of P. vivax infection in asymptomatic blood donors inhabiting forested areas of São Paulo state [ 22 ]. In fact, Mendrone et al .…”

Section: Introductionmentioning

confidence: 99%

“…In fact, Mendrone et al . [ 22 ] suggested that the P. falciparum real-time PCR positivity found in asymptomatic blood donors [ 21 ] could be an artifact. However, another study proposed that alternative dynamics of Plasmodium transmission may have evolved and caused the unexpected high frequencies of P. falciparum DNA in humans, the high level of antibodies against CSP in monkeys and Plasmodium -infected mosquito species other than Kerteszia [ 23 ].…”

Section: Introductionmentioning

confidence: 99%

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Plasmodium falciparum in the southeastern Atlantic forest: a challenge to the bromeliad-malaria paradigm?

Laporta

Burattini

Levy

et al. 2015

Malar J

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BackgroundRecently an unexpectedly high prevalence of Plasmodium falciparum was found in asymptomatic blood donors living in the southeastern Brazilian Atlantic forest. The bromeliad-malaria paradigm assumes that transmission of Plasmodium vivax and Plasmodium malariae involves species of the subgenus Kerteszia of Anopheles and only a few cases of P. vivax malaria are reported annually in this region. The expectations of this paradigm are a low prevalence of P. vivax and a null prevalence of P. falciparum. Therefore, the aim of this study was to verify if P. falciparum is actively circulating in the southeastern Brazilian Atlantic forest remains.MethodsIn this study, anophelines were collected with Shannon and CDC-light traps in seven distinct Atlantic forest landscapes over a 4-month period. Field-collected Anopheles mosquitoes were tested by real-time PCR assay in pools of ten, and then each mosquito from every positive pool, separately for P. falciparum and P. vivax. Genomic DNA of P. falciparum or P. vivax from positive anophelines was then amplified by traditional PCR for sequencing of the 18S ribosomal DNA to confirm Plasmodium species. Binomial probabilities were calculated to identify non-random results of the P. falciparum-infected anopheline findings.ResultsThe overall proportion of anophelines naturally infected with P. falciparum was 4.4% (21/480) and only 0.8% (4/480) with P. vivax. All of the infected mosquitoes were found in intermixed natural and human-modified environments and most were Anopheles cruzii (22/25 = 88%, 18 P. falciparum plus 4 P. vivax). Plasmodium falciparum was confirmed by sequencing in 76% (16/21) of positive mosquitoes, whereas P. vivax was confirmed in only 25% (1/4). Binomial probabilities suggest that P. falciparum actively circulates throughout the region and that there may be a threshold of the forested over human-modified environment ratio upon which the proportion of P. falciparum-infected anophelines increases significantly.ConclusionsThese results show that P. falciparum actively circulates, in higher proportion than P. vivax, among Anopheles mosquitoes of fragments of the southeastern Brazilian Atlantic forest. This finding challenges the classical bromeliad-malaria paradigm, which considers P. vivax circulation as the driver for the dynamics of residual malaria transmission in this region.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-015-0680-9) contains supplementary material, which is available to authorized users.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Plasmodium falciparum in the southeastern Atlantic forest: a challenge to the bromeliad-malaria paradigm?

Laporta

Burattini

Levy

et al. 2015

Malar J

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“…Initial studies of ITWL using insecticide-treated plastic sheeting (ITPS) demonstrated high mosquito mortality and reductions in malaria incidence in temporary labour shelters and refugee camps [ 17 – 20 ]. Subsequent, experimental hut trials of both pyrethroid and non-pyrethroid ITPS compared with LLINs have presented more equivocal results, which have been attributed to varying levels of insecticide resistance among vector populations [ 21 – 27 ]. The only community-level trial to evaluate carbamate-treated ITPS in combination with LLINs in an area of pyrethroid resistance in Benin reported no additional protection against malaria, potentially due to limited wall coverage and residual activity of the carbamate applied [ 28 ].…”

Section: Introductionmentioning

confidence: 99%

The effectiveness of non-pyrethroid insecticide-treated durable wall lining to control malaria in rural Tanzania: study protocol for a two-armed cluster randomized trial

et al. 2016

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BackgroundDespite considerable reductions in malaria achieved by scaling-up long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), maintaining sustained community protection remains operationally challenging. Increasing insecticide resistance also threatens to jeopardize the future of both strategies. Non-pyrethroid insecticidetreated wall lining (ITWL) may represent an alternate or complementary control method and a potential tool to manage insecticide resistance. To date no study has demonstrated whether ITWL can reduce malaria transmission nor provide additional protection beyond the current best practice of universal coverage (UC) of LLINs and prompt case management.Methods/designA two-arm cluster randomized controlled trial will be conducted in rural Tanzania to assess whether non-pyrethroid ITWL and UC of LLINs provide added protection against malaria infection in children, compared to UC of LLINs alone. Stratified randomization based on malaria prevalence will be used to select 22 village clusters per arm. All 44 clusters will receive LLINs and half will also have ITWL installed on interior house walls. Study children, aged 6 months to 11 years old, will be enrolled from each cluster and followed monthly to estimate cumulative incidence of malaria parasitaemia (primary endpoint), time to first malaria episode and prevalence of anaemia before and after intervention. Entomological inoculation rate will be estimated using indoor CDC light traps and outdoor tent traps followed by detection of Anopheles gambiae species, sporozoite infection, insecticide resistance and blood meal source. ITWL bioefficacy and durability will be monitored using WHO cone bioassays and household surveys, respectively. Social and cultural factors influencing community and household ITWL acceptability will be explored through focus-group discussions and in-depth interviews. Cost-effectiveness, compared between study arms, will be estimated per malaria case averted.DiscussionThis protocol describes the large-scale evaluation of a novel vector control product, designed to overcome some of the known limitations of existing methods. If ITWL is proven to be effective and durable under field conditions, it may warrant consideration for programmatic implementation, particularly in areas with long transmission seasons and where pyrethroid-resistant vectors predominate. Trial findings will provide crucial information for policy makers in Tanzania and other malaria-endemic countries to guide resource allocations for future control efforts.Trial registrationNCT02533336 registered on 13 July 2014.

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“…In the 2001–2004 study [ 4 ], it was used a multiplex PCR described by Rubio et al [ 27 ]. As the use of multiplex PCR may have affected the specificity of the test, the finding of P. falciparum DNA in this region may represent artifacts of the technique, indicating the presence of a species that is not in fact part of the transmission chain [ 28 ]. Nevertheless, in a recent study in fragments of Atlantic Forest in the southeast of Brazil, Laporta et al [ 29 ] identified anophelines naturally infected with P. falciparum and P. vivax , the latter in a smaller proportion of the infected mosquitoes.…”

Section: Discussionmentioning

confidence: 99%

Reassessment of asymptomatic carriers of Plasmodium spp. in an endemic area with a very low incidence of malaria in extra-Amazonian Brazil

Alencar

Malafronte

Cerutti

et al. 2017

Malar J

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BackgroundRegions with residual transmission are potential obstacles to the elimination of malaria. It is, therefore, essential to understand the factors associated with the maintenance of endemic malaria in these areas. The objective was to investigate whether the status of asymptomatic carriers of Plasmodium spp. DNA is maintained in the long term in an extra-Amazonian region of Brazil with low incidence, residual malaria transmission.MethodsAsymptomatic carriers of Plasmodium DNA detected in a survey carried out between 2001 and 2004 were reassessed between 2010 and 2011 using questionnaires, PCR and thick and thin blood smear tests three times at 3-month intervals.ResultsOf the 48 carriers detected between 2001 and 2004, 37 were located. Of these, only two had positive PCR results and, as in the first survey, Plasmodium malariae DNA was detected.ConclusionThe findings suggest that untreated dwellers from this extra-Amazonian region, who initially harbour malaria parasites, may become negative without ever developing apparent symptoms of the disease. Although the possibility of re-infection cannot be ruled out, the finding of two individuals harbouring P. malariae, both in the first and in the second survey, may be compatible with a long-term carrier state for this parasite. Since most clinical cases of malaria in the region are a consequence of infection by Plasmodium vivax, the epidemiological impact of such long-term carriage would be limited.

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Unexpected detection of Plasmodium vivax and Plasmodium falciparum DNA in asymptomatic blood donors: fact or artifact?

Cited by 10 publications

References 18 publications

Plasmodium falciparum in the southeastern Atlantic forest: a challenge to the bromeliad-malaria paradigm?

Plasmodium falciparum in the southeastern Atlantic forest: a challenge to the bromeliad-malaria paradigm?

The effectiveness of non-pyrethroid insecticide-treated durable wall lining to control malaria in rural Tanzania: study protocol for a two-armed cluster randomized trial

Reassessment of asymptomatic carriers of Plasmodium spp. in an endemic area with a very low incidence of malaria in extra-Amazonian Brazil

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