Natural infection of Plasmodium brasilianum in humans: Man and monkey share quartan malaria parasites in the Venezuelan Amazon.

BACKGROUND: The quartan malaria parasite Plasmodium malariae is the widest spread and best adapted human malaria parasite. The simian Plasmodium brasilianum causes quartan fever in New World monkeys and resembles P. malariae morphologically. Since the genetics of the two parasites are nearly identical, differing only in a range of mutations expected within a species, it has long been speculated that the two are the same. However, no naturally acquired infection with parasites termed as P. brasilianum has been found in humans until now. METHODS: We investigated malaria cases from remote Yanomami indigenous communities of the Venezuelan Amazon and analyzed the genes coding for the circumsporozoite protein (CSP) and the small subunit of ribosomes (18S) by species-specific PCR and capillary based-DNA sequencing. FINDINGS: Based on 18S rRNA gene sequencing, we identified 12 patients harboring malaria parasites which were 100% identical with P. brasilianum isolated from the monkey, Alouatta seniculus. Translated amino acid sequences of the CS protein gene showed identical immunodominant repeat units between quartan malaria parasites isolated from both humans and monkeys. INTERPRETATION: This study reports, for the first time, naturally acquired infections in humans with parasites termed as P. brasilianum. We conclude that quartan malaria parasites are easily exchanged between humans and monkeys in Latin America. We hypothesize a lack of host specificity in mammalian hosts and consider quartan malaria to be a true anthropozoonosis. Since the name P. brasilianum suggests a malaria species distinct from P. malariae, we propose that P. brasilianum should have a nomenclatorial revision in case further research confirms our findings. The expansive reservoir of mammalian hosts discriminates quartan malaria from other Plasmodium spp. and requires particular research efforts.

Conocimientos, actitudes y prácticas del personal de salud y de una muestra reducida de pacientes relacionados con la adherencia al tratamiento antimalárico, Municipio Atures, Estado Amazonas, Venezuela / Knowledge, attitudes and practices of health staff and a reduced sample of patients associated with adherence to antimalarial treatment in Atures Municipality, Amazonas State, Venezuela

El propósito de este trabajo fue estudiar los factores asociados con el sistema de salud y con los pacientes, que determinan la adherencia al tratamiento antimalárico en el municipio Atures, estado Amazonas. Se utilizó el Método Comparativo Constante como técnica cualitativa para el análisis de los datos recogidos mediante la observación participante y las entrevistas semi-estructuradas. Los resultados mostraron que las deficiencias del Programa de Control de Malaria, como errores en el diagnóstico, registro y seguimiento de los casos maláricos y suministro del tratamiento son factores que afectan negativamente la adherencia al tratamiento antimalárico. Por otro lado, las actitudes positivas de los pacientes ante el Programa de Control de Malaria y sus conocimientos sobre la enfermedad son factores que determinan una adherencia positiva. Sin embargo, la muestra reducida de pacientes no permite que los resultados concernientes a estos actores sean conclusivos.

The aim of this study was to investigate the factors that determine adherence to antimalarial treatment associated with the Malaria Control Program and patients in the Atures municipality, Amazonas state. The Constant Comparative Method was used as a qualitative technique for analyzing data collected through participant observation and semi-structured interviews. The results showed that deficiencies in the Malaria Control Program, such as misdiagnosis, mistakes in record keeping and monitoring of malaria cases, and treatment supply are all factors that negatively affect adherence to antimalarial treatment. On the other hand, patients´ positive attitudes to the control programme and their knowledge about the disease positively affected adherence to treatment. The small sample of patients meant, however, that the results obtained remain inconclusive.

Naturally acquired immune responses to malaria vaccine candidate antigens MSP3 and GLURP in Guahibo and Piaroa indigenous communities of the Venezuelan Amazon.

BACKGROUND: Malaria transmission in most of Latin America can be considered as controlled. In such a scenario, parameters of baseline immunity to malaria antigens are of specific interest with respect to future malaria eradication efforts. METHODS: A cross-sectional study was carried out in two indigenous population groups in Amazonas/Venezuela. Data from the regional malaria documentation system were extracted and participants from the ethnic groups of the Guahibo (n = 180) and Piaroa (n = 295) were investigated for the presence of Plasmodium parasites and naturally acquired antibodies to Plasmodium falciparum antigens in serum. The GMZ2 vaccine candidate proteins MSP3 and GLURP were chosen as serological markers. RESULTS: The incidence of P. falciparum in both communities was found to be less than 2%, and none of the participants harboured P. falciparum at the time of the cross-sectional. Nearly a quarter of the participants (111/475; 23,4%) had positive antibody titres to at least one of the antigens. 53/475 participants (11.2%) were positive for MSP3, and 93/475 participants (19.6%) were positive for GLURP. High positive responses were detected in 36/475 participants (7.6%) and 61/475 participants (12.8%) for MSP3 and GLURP, respectively. Guahibo participants had significantly higher antibody titres than Piaroa participants. CONCLUSIONS: Considering the low incidence of P. falciparum, submicroscopical infections may explain the comparatively high anti-P. falciparum antibody concentrations.

A rapid malaria appraisal in the Venezuelan Amazon.

BACKGROUND: While the federal state of Amazonas bears the highest risk for malaria in Venezuela (2007: 68.4 cases/1000 inhabitants), little comprehensive information about the malaria situation is available from this area. The purpose of this rapid malaria appraisal (RMA) was to provide baseline data about malaria and malaria control in Amazonas. METHODS: The RMA methodology corresponds to a rapid health impact assessment (HIA) as described in the 1999 Gothenburg consensus. In conjunction with the actors of the malaria surveillance system, all useful data and information, which were accessible within a limited time-frame of five visits to Amazonas, were collected, analysed and interpreted. RESULTS: Mortality from malaria is low (< 1 in 105) and slide positivity rates have stayed at the same level for the last two decades (15% +/- 6% (SD)). Active case detection accounts for ca. 40% of slides taken. The coverage of the censured population with malaria notification points (NPs) has been achieved in recent years. The main parasite is Plasmodium vivax (84% of cases). The proportion of Plasmodium falciparum is on the decline, possibly driven by the introduction of cost-free artemisinin-based combination therapy (ACT) (1988: 33.4%; 2007: 15.4%). Monitoring and documentation is complete, systematic and consistent, but poorly digitalized. Malaria transmission displayed a visible lag behind rainfall in the capital municipality of Atures, but not in the other municipalities. In comparison to reference microscopy, quality of field microscopy and rapid diagnostic tests (RDTs) is suboptimal (kappa < 0.75). Hot spots of malaria risk were seen in some indigenous ethnic groups. Conflicting strategies in respect of training of community health workers (CHW) and the introduction of new diagnostic tools (RDTs) were observed. CONCLUSION: Malaria control is possible, even in tropical rain forest areas, if the health system is working adequately. Interventions have to be carefully designed and the features of the particular local Latin American context considered.