Aldina Gonçalves

The importance of sensitive detection of malaria parasites in the human and insect hosts in epidemiological studies, as shown by the analysis of field samples from Guinea Bissau

A method based on the polymerase chain reaction (PCR) for highly sensitive detection and identification of human malaria parasites was applied to blood and mosquito samples obtained from a village in Guinea Bissau. The prevalence of parasites in the human population was shown to be greatly underestimated by microscopical examination. In particular, a high incidence of Plasmodium malariae and P. ovale parasites was revealed only by the PCR assay. Preliminary evidence was obtained to show that the distribution of P. malariae infections within the village was non-random. This was supported by analysis of the parasite species infecting the mosquito vector. The implication of these results for the design and interpretation of epidemiological surveys is discussed.

AIDS-related stigma and attitudes towards AIDS-infected people among adolescents.

Abstract This research examined the co-occurrence of accurate and inaccurate knowledge about HIV transmission among adolescents. Analyses were also conducted to examine the way in which variables related to demographic factors, personal characteristics, parent and peer relationships, and school involvement are associated with attitudes towards HIV/AIDS-infected people. Social and psychological processes that contribute to AIDS-related stigma are also described. Methods. Data were collected from the Portuguese sample of the ‘Health Behaviour in School-Aged Children – 2002 – a collaborative WHO study’. The study provided data representative of 6137 Portuguese adolescents at national level. Based on these results, we conducted 14 focus groups discussions. Results. Adolescents presented high levels of knowledge about HIV transmission. However, the proportion of young people who hold misperceptions is also high. A multiple regression analysis identified several associations with attitudes towards HIV-infected persons. The focus groups showed that adolescents believe that people with AIDS experienced discrimination and social exclusion. Adolescents’ opinions for HIV-infected persons were mostly positive and tolerant, although some adolescents showed an ambivalent attitude and undefined fears. Conclusion. These findings have significant implications to implement and design comprehensive interventions with impact in adolescents’ attitudes towards people with HIV/AIDS.

The epidemiology of malaria in prabis, Guinea, Bissau

This article reports upon a community survey of malaria in Prábis, Guinea-Bissau. A house to house census of the population was initially carried out from August to December 1991 (rainy season). After completing the census of each village, the population was invited to come, a week later, to a central point, where they were medically examined and finger-prick blood samples were collected for epidemiological characterization of the malaria situation in the area. The blood films of the one single village were used to compare the sensitivity and specificity of Polymerase Chain Reaction (PCR) with optical microscopy detection of parasites. In another village, the occurrence of parasitaemia was compared in children with and without fever. During the dry season, from March to June 1992, the population in each village was again invited to come to a central point. Some of the field procedures were repeated. The study revealed Prábis as an administrative Sector of Guinea-Bissau with endemic malaria, mostly due to Plasmodium falciparum, but with a significant rate of mixed infections. Active transmission occurred throughout the year, but it was more intensive during the rainy season and in the northwestern quadrant of the Sector. The level of endemicity of the village varied from hypo to holoendemic. The factors associated with the differences among villages included village size and predominant economic activity (closeness to rice fields). The transmission paradigm was, most likely, a mixture of malaria of the African wet Savannah and malaria associated with irrigated paddy fields. PCR proved to be a sensitive method with low specificity during the dry season. Pyraexia of 37.4 degrees C or higher in children aged 2-9 years is not a sensitive indicator of parasitaemia but, it is highly specific and it has a clinically useful predictive value.