Alvaro Augusto Couto

Duffy blood group gene polymorphisms among malaria vivax patients in four areas of the Brazilian Amazon region

BackgroundDuffy blood group polymorphisms are important in areas where Plasmodium vivax predominates, because this molecule acts as a receptor for this protozoan. In the present study, Duffy blood group genotyping in P. vivax malaria patients from four different Brazilian endemic areas is reported, exploring significant associations between blood group variants and susceptibility or resistance to malaria.MethodsThe P. vivax identification was determined by non-genotypic and genotypic screening tests. The Duffy blood group was genotyped by PCR/RFLP in 330 blood donors and 312 malaria patients from four Brazilian Amazon areas. In order to assess the variables significance and to obtain independence among the proportions, the Fishers exact test was used.ResultsThe data show a high frequency of the FYA/FYB genotype, followed by FYB/FYB, FYA/FYA, FYA/FYB-33 and FYB/FYB-33. Low frequencies were detected for the FYA/FYX, FYB/FYX, FYX/FYXand FYB-33/FYB-33 genotypes. Negative Duffy genotype (FYB-33/FYB-33) was found in both groups: individuals infected and non-infected (blood donors). No individual carried the FYX/FYB-33 genotype. Some of the Duffy genotypes frequencies showed significant differences between donors and malaria patients.ConclusionThe obtained data suggest that individuals with the FYA/FYB genotype have higher susceptibility to malaria. The presence of the FYB-33 allele may be a selective advantage in the population, reducing the rate of infection by P. vivax in this region. Additional efforts may contribute to better elucidate the physiopathologic differences in this parasite/host relationship in regions endemic for P. vivax malaria, in particular the Brazilian Amazon region.

Malária em região extra-Amazônica: situação no Estado de Santa Catarina

This study aimed to evaluate the malaria epidemiological aspects in Santa Catarina State, Brazil, by using National Health Foundation data from 1996 to 2001. From 4,707 thick smears analyzed 5.5% were positive. Plasmodium vivax was found in 69.0%; Plasmodium falciparum in 25.6%, mixed infection with both in 5%, and Plasmodium malariae in only 0.4%. It was observed that 67.4% were heterochthonous cases and 32.6% autochthonous cases. In recent years, the incidence of heterochthonous cases has increased. The majority of these cases come from the Brazilian Amazon region and the remainder from African countries. However, the municipalities of Joinville, Blumenau, Sao Francisco do Sul and Florianopolis registered higher rates of autochthonous cases in 1996/1997. Control and epidemiological surveillance are necessary to prevent the reintroduction of Plasmodium in this region. It would be useful to investigate each epidemiological setting in order to prevent the reappearance of the disease in areas currently considered under control.

Plasmodium vivax circumsporozoite variants and Duffy blood group genotypes in the Brazilian Amazon region

The circumsporozoite protein (CSP) of the Plasmodium vivax infective sporozoite is considered to be a major target for the development of recombinant malaria vaccines. The Duffy blood group molecule acts as the red blood cell receptor for P. vivax. We review the frequency of P. vivax CSP variants and report their association with the Duffy blood group genotypes from Brazilian Amazon patients carrying P. vivax malaria. Peripheral blood samples were collected from 155 P. vivax-infected individuals from five Brazilian malaria-endemic areas. The P. vivax CSP variants and the Duffy blood group genotypes were assessed using PCR/RFLP. In single infections, the VK210 variant was the commonest followed by the P. vivax-like variant. The typing of P. vivax indicated that the frequency of variants among the study areas was significantly different from one to another. This is the first detection of the VK247 and P. vivax-like variant in single infections in endemic areas of Brazil. Association of the CSP P. vivax variants with the heterozygous Duffy blood group system genotype was significant for VK210 single infection. These observations provide additional data on the Plasmodium-host interactions concerning the Duffy blood group and P. vivax capability of causing human malaria.

Frequencies of ABO, MNSs, and Duffy Phenotypes Among Blood Donors and Malaria Patients from Four Brazilian Amazon Areas

ABSTRACT We compared the serological phenotypic frequencies of ABO, MNSs, and Duffy in 417 blood donors and 309 malaria patients from four Brazilian Amazon areas. Our results suggest no correlation between ABO phenotype and malaria infection in all areas studied. We observed significant correlation between the S+s+, S+s−, and S−s+ phenotypes and malaria infection in three areas. Some of the Duffy phenotypes showed significant correlation between donors and malaria patients in different areas. These data are an additional contribution to the establishment of differential host susceptibility to malaria.

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.

Evolução da resistencia in vitro do Plasmodium falciparum a antimaláricos em área 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 ofgold mining exploration in Amapa State during theperiod ofl983 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 % ofresistance 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.

Evaluation of an immunochromatography test for malaria diagnosis under different storage conditions

This study aimed to evaluate the second-generation OptiMal test for malaria diagnosis under various storage conditions. It detected all the positive samples, except for two Plasmodium malariae samples. Further research evaluating diverse environmental conditions are important for ICT test applicability in Brazilian malaria areas.

Resistência in vitro de cepas do Plasmodium falciparum isoladas no sul do estado do Pará, em diferentes períodos: emergência de casos de multirresistência

O presente estudo avalia a resposta de cepas de Plasmodium falciparum as drogas antimalaricas, atraves de testes in vitro, isoladas em 7 municipios do sul do Estado do Para. Foram efetuados 69 testes para cloroquina e mefloquina, 62 para amodiaquina e 61 para quinino. Os resultados mostram elevada resistencia para cloroquina (71%), relativamente baixa resistencia para amodiaquina com (25,8%) e para o quinino apenas 8,2%. Mefloquina revela ampla sensibilidade (100%), mas, demonstrando perda da mesma quando comparada em dois periodos distintos. Evidenciou-se tambem cepas multirresistentes em dois dos municipios estudados.

In vitro studies on the levels of Plasmodium falciparum drug resistance from 1983 to 1986

Drug resistance tests were performed with 171 strains of P. falciparum obtained from the Amazon Region, using chloroquine, mefloquine, amodiaquine and quinine. Tests lasted about 24 hours and the drug solutions were prepared just before use. Results show high percentage of resistance to chloroquine (83%) whereas nearly all strains were shown to be sensitive to mefloquine (97.7%). For both amodiaquine and quinine sensitivities were of 51.0% and 56.5% respectively. The present study demonstrates that resistance to mefloquine may be starting in Tucurui, Para.

Characterization of P. falciparum strains obtained from recrudescent patients

Characterization of Plasmodium falciparum strains obtained from three patients interned in the Clinico-Pharmalogical Testing Centre of the Barros Barreto Hospital, Belem, Para, Brazil, was carried out using cellulose acetate electrophoresis for the two enzymes glucose phosphate isomerase EC.5.3.1.9 (GPI) and adenosine diaminase EC.3.5.4.4 (ADA) and sensibility tests for the two antimalarial drugs, chloroquin and mefloquine. This characterization showed an enzyme variant in one of the patients, and a modification in the chloroquine sensibility level in another; not only in the strains from the original infections, but also in those from each of the relapses.