Assessment of asymptomatic Plasmodium spp. infection by detection of parasite DNA in residents of an extra-Amazonian region of Brazil
Abstract Background The hypotheses put forward to explain the malaria transmission cycle in extra-Amazonian Brazil, an area of very low malaria incidence, are based on either a zoonotic scenario involving simian malaria, or a scenario in which asymptomatic carriers play an important role. Objectives...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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BMC
2018-03-01
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| Series: | Malaria Journal |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s12936-018-2263-z |
| _version_ | 1819041123832692736 |
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| author | Filomena E. C. de Alencar Rosely dos Santos Malafronte Crispim Cerutti Junior Lícia Natal Fernandes Julyana Cerqueira Buery Blima Fux Helder Ricas Rezende Ana Maria Ribeiro de Castro Duarte Antonio Ralph Medeiros-Sousa Angelica Espinosa Miranda |
| author_facet | Filomena E. C. de Alencar Rosely dos Santos Malafronte Crispim Cerutti Junior Lícia Natal Fernandes Julyana Cerqueira Buery Blima Fux Helder Ricas Rezende Ana Maria Ribeiro de Castro Duarte Antonio Ralph Medeiros-Sousa Angelica Espinosa Miranda |
| author_sort | Filomena E. C. de Alencar |
| collection | DOAJ |
| description | Abstract Background The hypotheses put forward to explain the malaria transmission cycle in extra-Amazonian Brazil, an area of very low malaria incidence, are based on either a zoonotic scenario involving simian malaria, or a scenario in which asymptomatic carriers play an important role. Objectives To determine the incidence of asymptomatic infection by detecting Plasmodium spp. DNA and its role in residual malaria transmission in a non-Amazonian region of Brazil. Methods Upon the report of the first malaria case in 2010 in the Atlantic Forest region of the state of Espírito Santo, inhabitants within a 2 km radius were invited to participate in a follow-up study. After providing signed informed consent forms, inhabitants filled out a questionnaire and gave blood samples for PCR, and thick and thin smears. Follow-up visits were performed every 3 months over a 21 month period, when new samples were collected and information was updated. Results Ninety-two individuals were initially included for follow-up. At the first collection, all of them were clearly asymptomatic. One individual was positive for Plasmodium vivax, one for Plasmodium malariae and one for both P. vivax and P. malariae, corresponding to a prevalence of 3.4% (2.3% for each species). During follow-up, four new PCR-positive cases (two for each species) were recorded, corresponding to an incidence of 2.5 infections per 100 person-years or 1.25 infections per 100 person-years for each species. A mathematical transmission model was applied, using a low frequency of human carriers and the vector density in the region, and calculated based on previous studies in the same locality whose results were subjected to a linear regression. This analysis suggests that the transmission chain is unlikely to be based solely on human carriers, regardless of whether they are symptomatic or not. Conclusion The low incidence of cases and the low frequency of asymptomatic malaria carriers investigated make it unlikely that the transmission chain in the region is based solely on human hosts, as cases are isolated one from another by hundreds of kilometers and frequently by long periods of time, reinforcing instead the hypothesis of zoonotic transmission. |
| first_indexed | 2024-12-21T09:20:00Z |
| format | Article |
| id | doaj.art-c353e29129be441db34c5a913b405ede |
| institution | Directory Open Access Journal |
| issn | 1475-2875 |
| language | English |
| last_indexed | 2024-12-21T09:20:00Z |
| publishDate | 2018-03-01 |
| publisher | BMC |
| record_format | Article |
| series | Malaria Journal |
| spelling | doaj.art-c353e29129be441db34c5a913b405ede2022-12-21T19:09:03ZengBMCMalaria Journal1475-28752018-03-0117111110.1186/s12936-018-2263-zAssessment of asymptomatic Plasmodium spp. infection by detection of parasite DNA in residents of an extra-Amazonian region of BrazilFilomena E. C. de Alencar0Rosely dos Santos Malafronte1Crispim Cerutti Junior2Lícia Natal Fernandes3Julyana Cerqueira Buery4Blima Fux5Helder Ricas Rezende6Ana Maria Ribeiro de Castro Duarte7Antonio Ralph Medeiros-Sousa8Angelica Espinosa Miranda9Graduate Programme in Infectious Diseases, Federal University of Espírito SantoProtozoology Laboratory, Institute of Tropical Medicine, University of São PauloGraduate Programme in Infectious Diseases, Federal University of Espírito SantoProtozoology Laboratory, Institute of Tropical Medicine, University of São PauloGraduate Programme in Infectious Diseases, Federal University of Espírito SantoGraduate Programme in Infectious Diseases, Federal University of Espírito SantoEntomology and Malacology Unit, Espírito Santo State Department of Health (SESA)Superintendency for the Control of Endemic Diseases (SUCEN), São Paulo State Department of HealthFaculty of Public Health, University of São PauloGraduate Programme in Infectious Diseases, Federal University of Espírito SantoAbstract Background The hypotheses put forward to explain the malaria transmission cycle in extra-Amazonian Brazil, an area of very low malaria incidence, are based on either a zoonotic scenario involving simian malaria, or a scenario in which asymptomatic carriers play an important role. Objectives To determine the incidence of asymptomatic infection by detecting Plasmodium spp. DNA and its role in residual malaria transmission in a non-Amazonian region of Brazil. Methods Upon the report of the first malaria case in 2010 in the Atlantic Forest region of the state of Espírito Santo, inhabitants within a 2 km radius were invited to participate in a follow-up study. After providing signed informed consent forms, inhabitants filled out a questionnaire and gave blood samples for PCR, and thick and thin smears. Follow-up visits were performed every 3 months over a 21 month period, when new samples were collected and information was updated. Results Ninety-two individuals were initially included for follow-up. At the first collection, all of them were clearly asymptomatic. One individual was positive for Plasmodium vivax, one for Plasmodium malariae and one for both P. vivax and P. malariae, corresponding to a prevalence of 3.4% (2.3% for each species). During follow-up, four new PCR-positive cases (two for each species) were recorded, corresponding to an incidence of 2.5 infections per 100 person-years or 1.25 infections per 100 person-years for each species. A mathematical transmission model was applied, using a low frequency of human carriers and the vector density in the region, and calculated based on previous studies in the same locality whose results were subjected to a linear regression. This analysis suggests that the transmission chain is unlikely to be based solely on human carriers, regardless of whether they are symptomatic or not. Conclusion The low incidence of cases and the low frequency of asymptomatic malaria carriers investigated make it unlikely that the transmission chain in the region is based solely on human hosts, as cases are isolated one from another by hundreds of kilometers and frequently by long periods of time, reinforcing instead the hypothesis of zoonotic transmission.http://link.springer.com/article/10.1186/s12936-018-2263-zMalariaPlasmodium vivaxPlasmodium malariaeAsymptomatic carrierPCR |
| spellingShingle | Filomena E. C. de Alencar Rosely dos Santos Malafronte Crispim Cerutti Junior Lícia Natal Fernandes Julyana Cerqueira Buery Blima Fux Helder Ricas Rezende Ana Maria Ribeiro de Castro Duarte Antonio Ralph Medeiros-Sousa Angelica Espinosa Miranda Assessment of asymptomatic Plasmodium spp. infection by detection of parasite DNA in residents of an extra-Amazonian region of Brazil Malaria Journal Malaria Plasmodium vivax Plasmodium malariae Asymptomatic carrier PCR |
| title | Assessment of asymptomatic Plasmodium spp. infection by detection of parasite DNA in residents of an extra-Amazonian region of Brazil |
| title_full | Assessment of asymptomatic Plasmodium spp. infection by detection of parasite DNA in residents of an extra-Amazonian region of Brazil |
| title_fullStr | Assessment of asymptomatic Plasmodium spp. infection by detection of parasite DNA in residents of an extra-Amazonian region of Brazil |
| title_full_unstemmed | Assessment of asymptomatic Plasmodium spp. infection by detection of parasite DNA in residents of an extra-Amazonian region of Brazil |
| title_short | Assessment of asymptomatic Plasmodium spp. infection by detection of parasite DNA in residents of an extra-Amazonian region of Brazil |
| title_sort | assessment of asymptomatic plasmodium spp infection by detection of parasite dna in residents of an extra amazonian region of brazil |
| topic | Malaria Plasmodium vivax Plasmodium malariae Asymptomatic carrier PCR |
| url | http://link.springer.com/article/10.1186/s12936-018-2263-z |
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