[Control of malaria transmission in a gold-mining area in Amapá State, Brazil, with participation by private enterprise]. / Controle da transmissão da malária em área de garimpo no Estado do Amapá com participação da iniciativa privada.

This paper reports on the epidemiological characterization of malaria following implementation of a program to control the endemic in a gold-mining area in northern Amapá State. The study focuses on total malaria cases in Amapá and the impact of the disease on the population, as represented by the Mineração Novo Astro S/A company and its employees as well as the community of Vila de Lourenço in the municipality of Calçoene, and adjacent gold miners. The effect of control measures in the program area is indicated by a significant reduction in malaria incidence and malaria-related morbidity and mortality. The importance of participation by private enterprise is emphasized, particularly in large projects for the control of endemic diseases (notably malaria) in the Amazon Region.

[Plasmodium vivax malaria in children and adolescents - epidemiological, clinical and laboratory features] / Malária por Plasmodium vivax em crianças e adolescentes - aspectos epidemiológicos, clínicos e laboratoriais.

OBJECTIVE: Evaluation of epidemiological, clinical and laboratory features of Plasmodium vivax malaria in children and adolescents. METHODS: This study was carried out in the Malaria Program of the Evandro Chagas Institute (Belém, Pará), from January 1995 to November 1996. 100 children and adolescents with the diagnosis of P. vivax malaria (thick blood film) were randomly enrolled. A protocol was created to assess epidemiological, clinical and laboratory parameters of this pathology. RESULTS: Malaria occurred in both sexes, and had a prevailing incidence among adolescents (37%). Most of the children and adolescents (92%) had been infected in the State of Pará. Autochthonous cases in the metropolitan area of Belém accounted for 34 % of the sample. Primary infection was seen in 80% of the patients. Fever was the major onset clinical symptom (88%). A history of typical febrile paroxysm was recorded in only 25% of the casuistic. In the first day of treatment (D0) fever (97%), chills (91%), pallor (85%), splenomegaly (46%) and hepatomegaly (29%) were some of the clinical features observed. Pallor (clinical signal) was found to be significantly (p=0.0004) associated with anemia (hemoglobin rate). There was a high significant negative correlation (p=0.0001) between delay of diagnosis (mean 12,5 days) and hemoglobin values. Regarding parasitological examination, just children and adolescents with positive results to hookworms were significantly (p=0.0133, p=0.0075) more anemic than those who had a positive parasitological examination to other helminths and/or protozoa species. CONCLUSIONS: Malaria affected children and adolescents from both sexes. An emphasis on epidemiological and clinical data is an important tool to the precocious diagnosis of the disease. Delay on diagnosis made anemia worse.

[Clinical efficacy of four schemes for vivax malaria treatment in children] / Eficácia de quatro esquemas terapêuticos para malaria vivax em crianças.

OBJECTIVES: In the treatment of vivax malaria, an important factor affecting the occurrence of relapse is the duration of treatment. In Belém, a number of patients with vivax malaria were found to be cured despite failure to complete the standard course of treatment. In Belém, a number of patients with vivax malaria were found to be cured despite failure to complete the standard course of treatment. This observation suggested the present study, investigating more practicable courses of treatment for children with vivax malaria.METHODS: A randomized prospective clinical trial was conducted in 200 outpatient children with vivax malaria. Parasite clearance time and response to four therapeutic schedules were investigated: a) chloroquine*, 10 mg/kg in a single dose (chloroquine SD) + primaquine, 0.50 mg/kg/dose for 7 days; b) chloroquine SD + primaquine, 0.25 mg/kg/dose for 7 days; c) chloroquine SD + primaquine, 0.50 mg/kg/dose for 5 days; d) chloroquine SD + primaquine, 0.25 mg/kg/dose for 5 days. Fisherss Exact test was used to compare the responses to the schedules.RESULTS: All 144 children who completed the study had clearance of asexual parasitemia by the fourth day of treatment. Significant differences were observed between schedules A/D (p= 0.022) and C/D (p= 0.005). A doubled dose of primaquine (schedules A and C) proved to be significantly more effective (p=0.0042) than the standard dose (B and D). However, duration of treatment had no significant effect (p = 0.6104).CONCLUSIONS: In this study, complete cure of vivax malaria was better achieved with a doubled dose of primaquine than with standard doses. Effectiveness of the doubled dose was independent of the duration of treatment. Treatment schedule D is not recommended.

[The evolution over time of the in-vitro resistance of Plasmodium falciparum to antimalarial drugs in 2 areas of the Brazilian Amazonia with distinct socioeconomic and geographic characteristics]. / Evolução temporal da resistência in vitro do Plasmodium falciparum às drogas antimaláricas em duas áreas da Amazônia Brasileira com distintas características sócio-econômicas e geográficas.

We evaluated the temporal progression of in vitro P. falciparum resistance to chloroquine, amodiaquine, quinine and mefloquine in two areas with distinct socioeconomical and geographical characteristics: Lourenço, in Amapá state and Paragominas, in Pará state. The former region is essentially an "open" gold mining camp, whereas the latter is one currently undergoing a colonization settlement process, in addition to expanding economical activities which mainly include cattle raising and wood exploitation. Our results show high resistance rates to chloroquine in the two study areas: 79.8% and 68.4% in Lourenço and Paragominas, respectively. Variations in the response of P. falciparum to both amodiaquine and quinine were recorded throughout the study period. On the other hand, no mefloquine P. falciparum resistant strains could be identified, despite the tact we had noted a decrease in sensitivity to this antimalarial drug throughout the study period.

Evoluçäo da resistência in vitro do Plasmodium falciparum a antimaláricos em área de prospecçäo de ouro no estado do Amapá, entre 1983-1990 / The evolution of in vitro resistance in Plasmodium falciparum to antimalarials in a gold-prospecting area in the state of Amapá between 1983 and 1990

Este estudo avalia a evoluçäo da sensibilidade in vitro do Plasmodium falciparum em uma área de prospecçäo de ouro no Estado do Amapá no período de 1983 a 1990. Foram efetuados 75 testes para cloroquina e quinino, 74 para amodiaquina e 76 para nefloquina. Os resultados revelaram 81 por cento de resistência à cloroquina e 27 por cento para a amodiaquina, enquanto que para quinino e mefloquina näo foram evidenciadas cepas resistentes. Contudo, para estas duas últimas drogas identificou-se uma crescente perda da sensibilidade ao longo do tempo. Aparentemente observa-se uma associaçäo entre resistência à cloroquina e a diminuiçäo da sensibilidade ao quinino

[The evolution of in-vitro resistance in Plasmodium falciparum to antimalarials in a gold-prospecting area in the state of Amapá between 1983 and 199)]. / Evolução da resistência in vitro do Plasmodium falciparum a antimaláricos em area de prospecção de ouro no Estado do Amapá, entre 1983 e 1990.

This study evaluates the sensitivity of P. falciparum in vitro to antimalarial drugs in an area of gold mining exploration in Amapá State during the period of 1983 to 1990. The following tests were done, 75 in vitro studies with chloroquine and quinine, 74 with amodiaquine and 76 with mefloquine. The results showed 81% of resistance to chloroquine and 27% to amodiaquine while resistant strains to quinine and mefloquine were found. Also for these two quinolinomethanols a loss of sensitivity was noticed in the period of study. An association between resistance to chloroquine and decrease of sensitivity to quinine was also evident with the same strains.

Resistência in vitro de cepas do Plasmodium falciparum isolodas no sul do estado do Pará, em diferentes períodos: emergência de casos de multirresistência / In vitro resistence of Plasmodium falciparum strains isolated in the south of the Pará state, in different periods: occurrence of cases of multiple resistence

O presente estudo avalia a resposta de cepas de Plasmodium falciparum às drogas antimaláricas, através de testes in vitro, isoladas em 7 municípios do sul do Estado do Pará. Foram efetuados 69 testes para cloroquina e mefloquina, 62 para amodiaquina e 61 para quinino. Os resultados mostram elevada resistência para cloroquina (71 por cento) relativamente baixa resistência para amodiaquina com (25,8 por cento) e para o quinino apenas 8,2 por cento. Mefloquina revela ampla sensibilidade (100 por cento), mas demonstrando perda da mesma quando comparada em dois períodos distintos. Evidenciou-se também cepas multirresistentes em dois dos municípios estudados

[In vitro resistance of Plasmodium falciparum strains isolated in the south of the Pará state, in different periods: occurrence of cases of multiple resistance]. / Resistência in vitro de cepas do Plasmodium falciparum isoladas no sul do Estado do Pará, em diferentes períodos: emergência de casos de multirresistência.

The responses of Plasmodium falciparum to antimalarial drugs were evaluated through the in vitro test using blood sample collected from patients of 7 municipalities of the south of Pará State. Sixty nine microtests for chloroquine and mefloquine, 62 for amodiaquine and 61 for quinine were performed. The results showed a high resistance for chloroquine (71%), a relatively low resistance level for amodiaquine (25.8%) and little resistance to quinine (8.2%). For mefloquine 100% of sensitivity was found.

Prevalence of the dihydrofolate reductase Asn-108 mutation as the basis for pyrimethamine-resistant falciparum malaria in the Brazilian Amazon.

Pyrimethamine resistance in cultivated laboratory isolates of Plasmodium falciparum is linked to the dihydrofolate reductase mutation Asn-108, a mutation that acts by interrupting drug binding within the active site of the enzyme. To determine the prevalence of this mutation in endemic regions harboring pyrimethamine-resistant malaria, we used a mutation-specific polymerase chain reaction assay to survey P. falciparum strains from a wide section of the Brazilian Amazon. Mutations were identified directly from blood samples without intervening steps of in vitro cultivation. Of 42 samples collected from four states in Brazil, 38 (90%) contained the Asn-108 codon AAC that confers pyrimethamine resistance, four samples contained only the wild-type Ser-108 codon AGC, and none contained the Thr-108 codon ACC found in cycloguanil-resistant pyrimethamine-sensitive strains. These findings indicate that a very high incidence of the Asn-108 DHFR mutation is responsible for pyrimethamine resistance in the Amazon, and they are consistent with recent failure rates reported for Fansidar (pyrimethamine-sulfadoxine). We suggest that limited use of proguanil be evaluated as an alternative to pyrimethamine.