Background: The changing epidemiology of malaria in Sub-Saharan Africa over the last decade needs further understanding. A longitudinal project on the epidemiology of malaria was set up in the Nyamisati village, Rufiji District, Tanzania in 1985. Cross-sectional surveys have revealed a gradual decrease in parasite prevalence over the last 25 years, from >90% to 13% (by PCR), despite the absence of large scale control interventions. Although PCR improves the detection of low-level parasitemia, assessment of parasite prevalence alone may not fully reflect the level of exposure in a population. In order to further understand the long-term dynamics of malaria transmission in this setting, we combined an assessment of parasite prevalence with analyses of IgG antibodies against antigens of the P. falciparum parasite and a salivary antigen of the Anopheles vector. Methodology: The study included children 1-16 years old participating in cross-sectional surveys in Nyamisati village in 1995, 1999 and 2010. Parasite prevalence was established by microscopy and PCR. Detection and quantification of IgG antibodies against P. falciparum whole schizont extract (PfSE) and Anopheles gambiae salivary gland protein 6 (gSG6) were performed with enzyme-linked immunosorbent assay (ELISA). Levels of IgG antibodies against merozoite surface protein 1-19 (MSP-119) and merozoite surface protein 2 (MSP-2) were assessed using a multiplexed bead-based immunoassay. Results and conclusions: The prevalence of anti-PfSE IgG as well as the levels of IgG antibodies against MSP-119 and MSP-2 decreased between 1995 and 2010, with the most marked reduction among the youngest children (1-4 years of age). The levels of anti-gSG6-IgG were, however, relatively stable over time. These findings suggest a substantially decreased intensity of malaria transmission in the Nyamisati area over the past 15 years, without an equally evident decrease in the population level of exposure to the malaria vector.
Understanding changing malaria transmission in a rural village, in coastal Tanzania, by assessment of IgG antibodies against Plasmodium falciparum and Anopheles gambiae antigens / Yman, V; Rono, J; Sandlund, J; Faraja, L; Johansson, M; Troye Blomberg, M; Boström, S; Ronca, R; Arca', Bruno; Homann, Mv; Osier, F; Premji, Z; Rooth, I; Färnert, A.. - STAMPA. - (2013), pp. 215-215. (Intervento presentato al convegno Ninth Annual BioMalPar Conference on the Biology and Pathology of the Malaria Parasite tenutosi a Heidelberg nel 13-15 May 2013).
Understanding changing malaria transmission in a rural village, in coastal Tanzania, by assessment of IgG antibodies against Plasmodium falciparum and Anopheles gambiae antigens.
ARCA', Bruno;
2013
Abstract
Background: The changing epidemiology of malaria in Sub-Saharan Africa over the last decade needs further understanding. A longitudinal project on the epidemiology of malaria was set up in the Nyamisati village, Rufiji District, Tanzania in 1985. Cross-sectional surveys have revealed a gradual decrease in parasite prevalence over the last 25 years, from >90% to 13% (by PCR), despite the absence of large scale control interventions. Although PCR improves the detection of low-level parasitemia, assessment of parasite prevalence alone may not fully reflect the level of exposure in a population. In order to further understand the long-term dynamics of malaria transmission in this setting, we combined an assessment of parasite prevalence with analyses of IgG antibodies against antigens of the P. falciparum parasite and a salivary antigen of the Anopheles vector. Methodology: The study included children 1-16 years old participating in cross-sectional surveys in Nyamisati village in 1995, 1999 and 2010. Parasite prevalence was established by microscopy and PCR. Detection and quantification of IgG antibodies against P. falciparum whole schizont extract (PfSE) and Anopheles gambiae salivary gland protein 6 (gSG6) were performed with enzyme-linked immunosorbent assay (ELISA). Levels of IgG antibodies against merozoite surface protein 1-19 (MSP-119) and merozoite surface protein 2 (MSP-2) were assessed using a multiplexed bead-based immunoassay. Results and conclusions: The prevalence of anti-PfSE IgG as well as the levels of IgG antibodies against MSP-119 and MSP-2 decreased between 1995 and 2010, with the most marked reduction among the youngest children (1-4 years of age). The levels of anti-gSG6-IgG were, however, relatively stable over time. These findings suggest a substantially decreased intensity of malaria transmission in the Nyamisati area over the past 15 years, without an equally evident decrease in the population level of exposure to the malaria vector.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
