RESUMEN
OBJECTIVE: To investigate the nutritional status of individuals from a rural area of Brazil, and associations with helminth infections in an age-stratified sample. METHOD: A total of 1113 individuals aged from 6 months to 83 years from the rural community of Americaninhas in Minas Gerais were investigated. Assessments comprised anthropometric measurements of weight, height and body composition, examining faecal samples for helminth eggs, and peripheral blood assays for albumin, haemoglobin and ferritin concentrations. RESULTS: Ten percent of the participants were underweight, 12.8% were overweight and 28.3% of the children and adolescents were stunted. 11.6% had low lean body mass and 28.8% had low fat body mass. Hypoalbuminaemia was seen in 5.5%, anaemia in 12.5% and iron deficiency in 13.1%, although the prevalence of these two indices increased with age. Multivariate analysis showed that, after controlling for age, sex and socio-economic status, stunting was significantly associated with Ascaris lumbricoides infection among children and adolescents, whereas low body mass was significantly associated with hookworm infection among adults and the elderly. CONCLUSIONS: Helminth infections are associated with undernutrition in endemic populations, with important differences between the effects of hookworm and A. lumbricoides on age-related nutritional status.
Asunto(s)
Ascariasis/epidemiología , Tamaño Corporal , Infecciones por Uncinaria/epidemiología , Parasitosis Intestinales/epidemiología , Desnutrición/epidemiología , Estado Nutricional , Adolescente , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Anemia Ferropénica/epidemiología , Anemia Ferropénica/parasitología , Animales , Ascaris lumbricoides , Brasil/epidemiología , Niño , Preescolar , Femenino , Ferritinas/deficiencia , Humanos , Hipoalbuminemia/epidemiología , Hipoalbuminemia/parasitología , Lactante , Masculino , Desnutrición/parasitología , Persona de Mediana Edad , Salud RuralRESUMEN
Surprisingly few detailed age-stratified data exist on the epidemiology of hookworm and iron status, especially in Latin America. We present data from a cross-sectional survey examining 1332 individuals aged 0-86 years from a community in south-east Brazil for hookworm, anaemia and iron deficiency. Sixty-eight percent of individuals were infected with the human hookworm Necator americanus. The force of infection (lambda=0.354) was similar to estimates from other areas of high hookworm transmission. Individuals from poorer households had significantly higher prevalence and intensity of infection than individuals from better-off households. The prevalence of anaemia, iron deficiency and iron-deficiency anaemia was 11.8%, 12.7% and 4.3%, respectively. Anaemia was most prevalent among young children and the elderly. Univariate analysis showed that haemoglobin and serum ferritin were both significantly negatively associated with hookworm intensity among both school-aged children and adults. Multivariate analysis showed that, after controlling for socio-economic status, iron indicators were significantly associated with heavy hookworm infection. Our results indicate that, even in areas where there is a low overall prevalence of anaemia, hookworm can still have an important impact on host iron status, especially in school-aged children and the elderly.
Asunto(s)
Anemia Ferropénica/epidemiología , Necatoriasis/epidemiología , Adolescente , Adulto , Distribución por Edad , Anciano , Anciano de 80 o más Años , Animales , Brasil/epidemiología , Niño , Preescolar , Estudios Transversales , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Necator americanus , Prevalencia , Análisis de Regresión , Distribución por SexoRESUMEN
Marked heterogeneity exists in the patterns of parasitic infection between individuals, households and communities. Analysis of parasite distributions within populations is complicated by the fact that parasite distributions are highly aggregated and few studies have explicitly incorporated this distribution when investigating small-scale spatial heterogeneities. This study aimed to quantify the small-scale (within- and between-household) heterogeneity of helminth infection in an area of Minas Gerais State, Brazil, with rural and urban sectors. Parasitological data from a cross-sectional survey of 1,249 individuals aged 0-86 years from 242 households were analysed. Within-household clustering of infection was assessed using random effect logistic regression models and between-household spatial heterogeneity was assessed using a Bayesian negative binomial spatial model. The overall prevalence of hookworm (Necator americanus) was 66.9%, the prevalence of Schistosoma mansoni was 44.9% and the prevalence of Ascaris lumbricoides was 48.8%. Statistical analysis indicated significant (within) household and (between household) spatial clustering of hookworm in both rural and urban areas and of S. mansoni in rural areas. There was no evidence of either household or spatial clustering of S. mansoni in urban areas. The spatial correlation of S. mansoni was estimated to reduce by half over a distance of 700 m in the rural area. Rural hookworm had a much smaller half-distance (28 m) and urban hookworm showed an even smaller half-distance (12 m). We suggest that such species-specific differences in patterns of infection by environment are primarily due to variation in exposure and parasite life cycle, although host genetic factors cannot be ruled out.
Asunto(s)
Helmintiasis/epidemiología , Parasitosis Intestinales/epidemiología , Población Rural , Población Urbana , Adolescente , Adulto , Distribución por Edad , Anciano , Anciano de 80 o más Años , Animales , Ascariasis/epidemiología , Ascaris lumbricoides , Brasil/epidemiología , Niño , Preescolar , Estudios Transversales , Composición Familiar , Heces/parasitología , Femenino , Infecciones por Uncinaria/epidemiología , Humanos , Lactante , Recién Nacido , Estadios del Ciclo de Vida , Masculino , Persona de Mediana Edad , Recuento de Huevos de Parásitos , Prevalencia , Esquistosomiasis/epidemiología , Esquistosomiasis mansoni , Distribución por Sexo , Medio SocialRESUMEN
OBJECTIVE: To identify possible synergistic associations of hookworm and other helminths. METHOD: Cross-sectional survey of all households within 10 km2 of Americaninhas, a rural community in Minas Gerais, Brazil. We determined the prevalence and intensity of single and multiple helminth species infection in an age-stratified sample of 1332 individuals from 335 households. RESULTS: Hookworm was the most prevalent helminth infection (68.2%), followed by Ascaris lumbricoides (48.8%) and Schistosoma mansoni (45.3%). Overall, 60.6% of individuals harboured mixed helminth infections. Multivariate analysis indicated significant positive associations for co-infection with hookworm and S. mansoni and for co-infection with hookworm and A. lumbricoides. Co-infections with hookworm and A. lumbricoides resulted in higher egg counts for both, suggesting a synergistic relationship between these species, although, we found important age differences in this relationship. However, the intensity of S. mansoni or A. lumbricoides co-infection did not differ from that of mono-infection. CONCLUSION: These results have implications for the epidemiology, immunology and control of multiple helminth infections. More research is needed to examine the rates of re-infection and immune responses after chemotherapy, and to what extent the effects of polyparasitism are altered by chemotherapy.