Parturientes adolescentes em Cruzeiro do Sul, Acre, Brasil: características socioeconômicas e obstétricas / Adolescent pregnancy in Cruzeiro do Sul, Acre, Brazil: socioeconomic characteristics, prenatal and obstetric care

Resumo O objetivo do estudo foi investigar as características socioeconômicas e obstétricas de parturientes adolescentes e suas complicações sobre a saúde materna e neonatal. Trata-se de uma análise de dados da linha de base da coorte de nascimentos MINA-Brasil conduzida no município de Cruzeiro do Sul, estado do Acre. Utilizou-se teste qui-quadrado para comparar características das puérperas adolescentes com as adultas e modelos múltiplos de regressão de Poisson com variância robusta para avaliar fatores associados. Entre as puérperas estudadas, 26,2% (IC95%: 24,0-28,4) eram adolescentes. Os fatores associados ao parto na adolescência foram ter nove anos ou menos de estudo (RPaj:1,36; IC95%: 1,14-1,61), pertencer aos menores quartis do índice de riqueza (1° quartil: RPaj:1,40; IC95%: 1,08-1,80) (2° quartil: RPaj:1,37; IC95%: 1,08-1,74), ser primigesta (RPaj:3,69; IC95%: 2,98-4,57), baixo IMC pré-gestacional (RPaj:1,28; IC95%: 1,04-1,57), infecção urinária na gravidez (RPaj:1,25; IC95%: 1,07-1,46) e menos de seis consultas de pré-natal (RPaj:1,42; IC95%: 1,21-1,66). Pobreza, baixa escolaridade, primigestação, baixo IMC pré-gestacional, infecção urinária na gestação e menor número de consultas de pré-natal foram associados ao parto na adolescência em município da região Norte do Brasil.

Abstract The present study aimed to investigate the socioeconomic and obstetric characteristics of adolescent mothers and the complications they cause to maternal and neonatal health. This baseline data analysis of the MINA-Brazil birth cohort was conducted in the municipality of Cruzeiro do Sul, state of Acre, Brazil. The chi-square test was used to compare characteristics of adolescent and adult postpartum women, and multiple Poisson regression models with robust variance were used to assess associated factors. Among the postpartum women, 26.2% (95%CI: 24.0-28.4) were adolescents. Factors associated with childbirth in adolescence included: nine years or less of schooling (adjPR:1.36; 95%CI: 1.14-1.61), belongs to the lowest quartiles of the wealth index (1st quartile: adjPR:1.40; 95%CI: 1.08-1.80) (2nd quartile: adjPR:1.37; 95%CI: 1.08-1.74), primigravidae (adjPR:3.69; 95%CI: 2.98-4.57), low pre-pregnancy BMI (adjPR:1.28; CI95%: 1.04-1.57), urinary tract infection during pregnancy (adjPR:1.25; CI95%: 1.07-1.46) and less than six prenatal consultations (adjPR:1.42; 95%CI: 1.21-1.66). Poverty, little schooling, primigravidae, low pre-pregnancy BMI, urinary tract infection during pregnancy and few prenatal consultations were associated with childbirth during adolescence in a municipality in the Northern region of Brazil.

Clinically silent Plasmodium vivax infections in native Amazonians of northwestern Brazil: acquired immunity or low parasite virulence?

BACKGROUND Malaria remains common among native Amazonians, challenging Brazil′s elimination efforts. OBJECTIVES We examined the epidemiology of malaria in riverine populations of the country′s main hotspot - the upper Juruá Valley in Acre state, close to the Brazil-Peru border, where Plasmodium vivax accounts for > 80% of cases. METHODS Participants (n = 262) from 10 villages along the Azul River were screened for malaria parasites by microscopy and genus-specific, cytochrome b (cytb) gene-based polymerase chain reaction. Positive samples were further tested with quantitative TaqMan assays targeting P. vivax- and P. falciparum-specific cytb domains. We used multiple logistic regression analysis to identify independent correlates of P. vivax infection. FINDINGS Microscopy detected only one P. vivax and two P. falciparum infections. TaqMan assays detected 33 P. vivax infections (prevalence, 11.1%), 78.1% of which asymptomatic, with a median parasitaemia of 34/mL. Increasing age, male sex and use of insecticide-treated bed nets were significant predictors of elevated P. vivax malaria risk. Children and adults were similarly likely to remain asymptomatic once infected. MAIN CONCLUSIONS Our findings are at odds with the hypothesis of age-related clinical immunity in native Amazonians. The low virulence of local parasites is suggested as an alternative explanation for subclinical infections in isolated populations.

A Retrospective Survey of Rodent-borne Viruses in Rural Populations of Brazilian Amazon

Abstract INTRODUCTION: The Amazon tropical rainforest has the most dense and diverse ecosystem worldwide. A few studies have addressed rodent-borne diseases as potential hazards to humans in this region. METHODS: A retrospective survey was conducted using enzyme-linked immunosorbent assay for detecting mammarenavirus and orthohantavirus antibodies in 206 samples collected from rural settlers of the Brazilian Western Amazonian region. RESULTS: Six (2.91%) individuals in the age group of 16 to 36 years were found to possess antibodies against mammarenavirus. CONCLUSION: Evidence of previous exposure to mammarenavirus in the rural population points to its silent circulation in this region.

Emerging Plasmodium vivax resistance to chloroquine in South America: an overview

The global emergence of Plasmodium vivax strains resistant to chloroquine (CQ) since the late 1980s is complicating the current international efforts for malaria control and elimination. Furthermore, CQ-resistant vivax malaria has already reached an alarming prevalence in Indonesia, East Timor and Papua New Guinea. More recently, in vivo studies have documented CQ-resistant P. vivax infections in Guyana, Peru and Brazil. Here, we summarise the available data on CQ resistance across P. vivax-endemic areas of Latin America by combining published in vivo and in vitro studies. We also review the current knowledge regarding the molecular mechanisms of CQ resistance in P. vivax and the prospects for developing and standardising reliable molecular markers of drug resistance. Finally, we discuss how the Worldwide Antimalarial Resistance Network, an international collaborative effort involving malaria experts from all continents, might contribute to the current regional efforts to map CQ-resistant vivax malaria in South America.

Molecular markers and genetic diversity of Plasmodium vivax

Enhanced understanding of the transmission dynamics and population genetics for Plasmodium vivax is crucial in predicting the emergence and spread of novel parasite phenotypes with major public health implications, such as new relapsing patterns, drug resistance and increased virulence. Suitable molecular markers are required for these population genetic studies. Here, we focus on two groups of molecular markers that are commonly used to analyse natural populations of P. vivax. We use markers under selective pressure, for instance, antigen-coding polymorphic genes, and markers that are not under strong natural selection, such as most minisatellite and microsatellite loci. First, we review data obtained using genes encoding for P. vivax antigens: circumsporozoite protein, merozoite surface proteins 1 and 3α, apical membrane antigen 1 and Duffy binding antigen. We next address neutral or nearly neutral molecular markers, especially microsatellite loci, providing a complete list of markers that have already been used in P. vivax populations studies. We also analyse the microsatellite loci identified in the P. vivax genome project. Finally, we discuss some practical uses for P. vivax genotyping, for example, detecting multiple-clone infections and tracking the geographic origin of isolates.

Naturally acquired antibodies to merozoite surface protein (MSP)-1(19) and cumulative exposure to Plasmodium falciparum and Plasmodium vivax in remote populations of the Amazon Basin of Brazil

To infer recent patterns of malaria transmission, we measured naturally acquired IgG antibodies to the conserved 19-kDa C-terminal region of the merozoite surface protein (MSP)-1 of both Plasmodium vivax (PvMSP-1(19)) and Plasmodium falciparum (PfMSP-1(19)) in remote malaria-exposed populations of the Amazon Basin. Community-based cross-sectional surveys were carried out between 2002 and 2003 in subjects of all age groups living along the margins of the Unini and Jaú rivers, Northwestern Brazil. We found high prevalence rates of IgG antibodies to PvMSP-1(19) (64.0 - 69.6 percent) and PfMSP-1(19) (51.6 - 52.0 percent), with significant differences in the proportion of subjects with antibodies to PvMSP-1(19) according to age, place of residence and habitual involvement in high-risk activities, defining some groups of highly exposed people who might be preferential targets of malaria control measures. In contrast, no risk factor other than age was significantly associated with seropositivity to PfMSP-1(19). Only 14.1 percent and 19.3 percent of the subjects tested for antibodies to PvMSP-1(19) and PfMSP-1(19) in consecutive surveys (142 - 203 days apart) seroconverted or had a three fold or higher increase in the levels of antibodies to these antigens. We discuss the extent to which serological data correlated with the classical malariometric indices and morbidity indicators measured in the studied population at the time of the seroprevalence surveys and highlight some limitations of serological data for epidemiological inference.

Child health and nutrition in the Western Brazilian Amazon: population-based surveys in two counties in Acre State

The article presents prevalence rates for malnutrition, intestinal parasitic infections, anemia, and iron deficiency in under-five children in a population-based cross-sectional survey performed in the urban area of two counties in the Western Brazilian Amazon, Assis Brasil (n = 200) and Acrelandia (n = 477). Available data included: (a) weight and height measurements, standardized as z-scores using the 1977 NCHS reference population, (b) diagnosis of current intestinal parasitic infection, (c) blood hemoglobin levels, and (d) plasma ferritin and soluble transferrin receptor levels. Overall prevalence rates of low weight-for-height, low weight-for-age, and low height-for-age were 3.7 percent, 8.7 percent, and 7.5 percent, respectively, with similar figures in the two towns. Intestinal parasites were detected in 32.5 percent children; helminths were uncommon. Anemia and iron deficiency were diagnosed in 30.6 percent and 43.5 percent of the children, respectively. Evidence of anemia was found in only 47.6 percent of the children with depleted iron reserves, indicating that hemoglobin measurement alone would severely underestimate the magnitude of iron deficiency in this population. In both towns, anemia and malnutrition were significantly more prevalent among children in the lowest socioeconomic stratum.

As prevalências de desnutrição, parasitoses intestinais, anemia e deficiência de ferro foram avaliadas, por meio de inquéritos transversais de base populacional, em pré-escolares na área urbana de dois municípios das Amazônia Ocidental Brasileira, Assis Brasil (n = 200) e Acrelândia (n = 477). Os índices antropométricos peso/estatura (P/E), peso/idade (P/I) e estatura/idade (E/I) foram calculados como escores z, com base na população de referência do National Center for Health Statistics de 1977. Diagnosticaram-se déficits nutricionais segundo índices P/E, P/I e E/I em 3,7 por cento, 8,7 por cento e 7,5 por cento das crianças, respectivamente. Encontraram-se parasitas intestinais em 32,5 por cento das 554 amostras examinadas, sendo raras as infecções por helmintos. Com base nos níveis de hemoglobina sangüínea e níveis plasmáticos de ferritina e receptor solúvel de transferrina, diagnosticaram-se anemia e deficiência de ferro em 30,6 por cento e 43,5 por cento das crianças, respectivamente. Somente 47,6 por cento das crianças com deficiência de ferro tinham anemia, indicando que a medida isolada de hemoglobina sangüínea subestima a magnitude da deficiência de ferro nesta população. Nos dois municípios, a anemia e a desnutrição foram significantemente mais prevalentes entre as crianças de famílias dos estratos sócio-econômicos mais baixos.

Prevalence and spatial distribution of intestinal parasitic infections in a rural Amazonian settlement, Acre State, Brazil / Prevalência e distribuição espacial de parasitoses intestinais em assentamento agrícola na Amazônia rural, Acre, Brasil

A population-based survey of the prevalence and spatial distribution of intestinal parasitism was carried out in an agricultural settlement in the Amazon Basin of Brazil (Granada, Acre State). More than half (53.4 percent) of the 429 stool specimens from subjects in all age groups, living in 113 households, had cysts, ova, or larvae of intestinal parasites. The most prevalent parasites were Giardia duodenalis (19.6 percent) and soil-transmitted helminths (12.7 percent); 105 (24.5 percent) subjects were infected with more than one species of parasite. Significant age-related differences in prevalence were only found for G. duodenalis (children < 1 year and adults > 30 years were less affected). Six households (5.3 percent), situated within a radius of 690m, comprised 48.1 percent of all subjects harboring soil-transmitted helminths in our study area. Households within this cluster were poorer and more crowded than those outside the cluster. The observed spatial clustering of infections with soil-transmitted helminths provides valuable information for the spatial targeting of sanitary interventions in this area.

Estudo de base populacional sobre a prevalência e distribuição de parasitoses intestinais foi realizado em assentamento agrícola na Amazônia Brasileira (Granada, Acre). Mais da metade (53,4 por cento) das 429 amostras analisadas de indivíduos de todas as idades, moradores de 113 domicílios, continha cistos, ovos ou larvas de parasitas intestinais. Os parasitas intestinais de maior prevalência foram Giardia duodenalis (19,6 por cento) e os geo-helmintos (12,7 por cento); 105 (24,5 por cento) indivíduos apresentavam co-infecção por mais de uma espécie de parasita. Houve diferença significativa em relação à idade na prevalência somente de G. duodenalis (crianças < 1 ano e adultos > 30 anos foram menos afetados). Seis domicílios (5,3 por cento), localizados num raio de 690m, concentraram 48,1 por cento de todos os indivíduos infectados por geo-helmintos na área de estudo. Domicílios incluídos nesse agregado (cluster) eram mais pobres e com maior número de habitantes do que os domicílios localizados fora do agregado. A distribuição espacial dos agregados de casos de infecção por geo-helmintos fornece informações valiosas para intervenções sanitárias na comunidade da área de estudo.

The Acre Project: the epidemiology of malaria and arthropod-borne virus infections in a rural Amazonian population

The authors describe the baseline malaria prevalence and arbovirus seroprevalence among 467 subjects in an ongoing cohort study in rural Amazonia. Most subjects (72.2 percent) reported one or more previous episodes of malaria, and 15.6 percent had been hospitalized for malaria, but only 3.6 percent of individuals five years or older had malaria parasites detected by microscopy (10 with Plasmodium vivax and 4 with P. falciparum). Antibodies to Alphavirus, Orthobunyavirus, and/or Flavivirus were detected by hemagglutination inhibition (HI) in 42.6 percent of subjects aged five years or older, with a higher seropositivity rate among males (49.2 percent) than females (36.2 percent). Since 98.9 percent of subjects had been immunized for yellow fever, the presence of cross-reactive antibodies to dengue and other Flaviviruses cannot be ruled out, but at least 12 subjects (3.3 percent) with IgM antibodies to dengue virus detected by ELISA had a putative recent exposure to this virus.

Tendência secular das parasitoses instestinais na infância na cidade de Säo Paulo (1984-1996) / Secular trends in child intestinal parasitic diseases in S. Paulo city, Brazil (1984-1996)

Objetivo: Estimar a prevalência e a distribuiçäo social das parasitoses intestinais na infância, estabelecer a tendência secular dessas enfermidades e analisar sua determinaçäo com base em dois inquéritos domiciliares realizados na cidade de Säo Paulo, SP, em 1984/85 e 1995/96. Métodos: Os inquéritos estudaram amostras probabilísticas da populaçäo residente na cidade com idades entre zero e 59 meses (1.016 em 1984/85 e 1.280 em 1995/96). Amostras de fezes foram coletadas nos dois inquéritos e submetidas a exame parasitológico pela técnica de sedimentaçäo, realizando-se leituras de preparaçöes simples e de preparaçöes coradas com lugol para exame de cistos de protozoários. O estudo da distribuiçäo social das parasitoses levou em conta tercis da renda familiar per capita em cada um dos inquéritos. A estratégia analítica para estudar os determinantes da evoluçäo da prevalência das parasitoses na populaçäo empregou modelos hierárquicos de causalidade, análises multivariadas de regressäo e procedimentos análogos aos utilizados para calcular riscos atribuíveis populacionais. Resultados/Conclusöes: Houve entre os inquéritos reduçöes expressivas na prevalência das parasitoses em geral (de 30,9 por cento para 10,7 por cento), das helmintoses (de 22,3 por cento para 4,8 por cento), da giardíase (de 14,5 por cento para 5,5 por cento) e do poli-parasitismo intestinal (de 13,1 por cento para 0,5 por cento). Embora declínios intensos tenham sido observados em todos estratos sociais, manteve-se inalterada no período a forte relaçäo inversa entre nível de renda e ocorrência de parasitismo. Mudanças positivas em determinantes distais (renda familiar e escolaridade materna) e intermediários (moradia, saneamento do meio e acesso a serviços de saúde) das helmintoses justificaram parte substancial da reduçäo de sua prevalência. A reduçäo da giardíase foi atribuída a melhorias na escolaridade materna e nas condiçöes de moradia e saneamento. A duplicaçäo da freqüência a creches refreou o declínio da giardíase no período

How prevalent is Plasmodium malariae in Rondônia, Western Brazilian Amazon? / Qual é a prevalência de Plasmodium malariae em Rondônia, Amazônia Ocidental Brasileira?

Comparam-se neste trabalho resultados de identificaçäo de espécie de Plasmodium obtidos com a microscopia convencional de gotas espessas coradas pelo Giemsa, realizada no local, e um protocolo semi-aninhado de reaçäo em cadeia da polimerase (PCR) em 96 pacientes maláricos de Rondônia, Amazônia Ocidental Brasileira. Infecçöes envolvendo mais de uma espécie foram detectadas através de PCR em 30 por cento dos pacientes, mas nenhum caso havia sido encontrado pelo exame de gotas espessas. Além disso, encontraram-se infecçöes gor P. malariae por PCR em 9 dos 96 pacientes (10 por cento), mas nenhuma havia sido encontrada pelos microscopistas locais. Discute-se o potencial impacto de erros de identificaçäo de espécie sobre o tratamento e o controle da malária

Allelic diversity at the Merozoite surface protein-1 (MSP-1) locus in natural Plasmodium falciparum populations: a brief overview

The merozoite surface protein-1 (MSP-1) locus of Plasmodium falciparum codes for a major asexual blood-stage antigen currently proposed as a major malaria vaccine candidate. The protein, however, shows extensive polymorphism, which may compromise its use in sub-unit vaccines. Here we compare the patterns of allelic diversity at the MSP-1 locus in wild isolates from three epidemiologically distinct malaria-endemic areas: the hypoendemic southwestern Brazilian Amazon (n=54), the mesoendemic southern Vietnam (n=238) and the holoendemic northern Tanzania (n=79). Fragments of the variable blocks 2, 4a, 4b and 6 or 10 of this single-copy gene were amplified by the polymerase chain reaction, and 24 MSP-1 gene types were defined as unique combinations of allelic types in each variable block. Ten different MSP-1 types were identified in Brazil, 23 in Vietnam and 13 in Tanzania. The proportion of genetically mixed infections (isolates with carrying more one MSP-1 version) ranged from 39 per cent in Brazil to 44 per cent in Vietnam and 60 per cent in Tanzania. The vast majority (90 per cent) of the typed parasite populations from Brazil and Tanzania belonged to the same seven most frequent MSP-1 gene types. In contrast, these seven types corresponded to only 61 per cent of the typed parasite populations from Vietnam. Non-random associations were found between allelic types in blocks 4a and 6 among Vietnamese isolates, the same pattern being observed in independent studies performed in 1994, 1995 and 1996. These results suggest that MSP-1 is under selective pressure in the local parasite population. Nevertheless, the finding that similar MSP-1 type frequencies were found in 1994 and 1996 argues against the prominence of short-term frequency-dependent immune selection of MSP-1 polymorphisms. Non-random associations between MSP-1 allelic types, however, were not detected among isolates from Brazil and Tanzania. A preliminary analysis of the distribution od MSP-1 gene types per host among isolates from Tanzania, but not among those from Brazil and Vietnam, shows significant deviation from that expected under the null hypothesis of independent distribution of parasites carrying different gene types in the human hosts. Some epidemiological consequences of these findings are discussed.

Diversidade antigênica na proteína principal da superfície de merozoítos (MSP-1) de palsmodium falciparum: implicações para o desenvolvimento de vacinas antimaláricas / Antigenic diversity in the major merozoite surface protein (MSP-1) of palsmodium falciparum: implications for malaria vaccine developmemt

Considera-se ataulamente a proteína principal de merozoítos (merozoite surface protein-1 ou MSP-1) um dos principais antígenos de fase assexuada sangüinea de Plasmodium falciparum, mas seu extenso polimorfismo pode comprometer seu uso em vacinas antimaláricas. Este trabalho examina os padrões de diversidade alélica do gene que codifica a MSP-1 em isolados de pacientes sintomáticos provenientes de três regiões malarígena. As implicações desses achados são discutidos no contexto da biologia populacional de p. falciparum e do desenvolvimento de vacinas anti-maláricas

Diversidade alélica da proteína principal da superfície de merozoítos(MSP-1) em populaçöes naturais de Plasmodium falciparum / Allelic diversity in the merozite surface protein-1(MSP-1)in natural Plasmodium falciparum populations

Considera-se atualmente a proteína principal de merozoítos (merrozoite surface protein-1 ou MSP-1) de Plasmodium falciparum um dos principais antígenos de fase assexuada sanguínea, mas seu extenso polimorfismo pode comprometer seu uso em vacinas antimaláricas. Este trabalho examina os padröes de diversidade alélica do gene que codifica a MSP-1 em isolados de pacientes sintomáticos provenientes de três regiöes malarígenas: em área hipoendêmica no sudoeste da Amazônia brasileira (n=54), um área holoendêmica no norte da Tânzania (n=79). Amplificaram-se fragmentos dos blocos variâveis 2,4a, 4b e 6 ou 10 desse gene de cópia única através de reaçäo de polimerase em cadeia (PCR). Vinte e quatro tipos principais de MSP-1 foram definidos como combinaçöes identificados no Brasil, 23 no Vietnam e 13 na Tanzânia...

Prevalence and levels of IgG and IgM antibodies against Plasmodium falciparum and P. vivax in blood donors from Rondônia, Brazilian Amazon

Antibodies of IgG and IgM isotopes reacting with Plasmodium falciparum and P. vivax thick-smear antigens were searched for by the indirect fluorescent antibody test (IFAT) in a random sample of 230 blood donors at the transfusion centre of Porto Velho (HEMERON), Rondônia State, western Brazilian Amazon. A high prevalence of IgG seropositivity (32% against P. falciparum, 24% against P. vivax and 37% against either P. falciparum or P. vivax antigens) was detected among them, despite the fact that candidates reporting recent (<12 months) malaria attacks were not elegible. Only a small proportion of them had also detectable IgM antibodies to these antigens. These data suggest an intense, relatively recent exposure to malaria in such an urban population sample. However, parasitaemia (as detected by microscopical examination of Giemsa-stained thick smears) was patent in only one prospective donor. The antibody profile of blood donors was compared with that of healthy subjects of all age groups, living in a close endemic area (Candeias village, 21 km east of Porto Velho). The villagers were classified into two groups according to their history of a recent (<12 months) or a remote (>12 months) past malaria attack due to either P. falciparum or P. vivax. Extensive overlapping was observed when the distribution of antibody titres of healthy subjects from Candeias village with a recent and remote malaria history was compared. In conclusion, subjects with a recent or a remote malaria history could not be distinguished by sorological criteria alone