Intestinal parasites in children of urban areas of the Cordillera province (Bolivia)

The World Health Organization estimates that over 3.5 billion people worldwide are infected with intestinal parasites responsible for malnutrition and anaemia, particularly in poor communities of developing countries, where children are the most vulnerable subjects. In this study we report the results of a survey (MAE project ‘‘Fortalecimiento de la red de salud del Chaco Boliviano: una perspectiva comunitaria’’) carried out to detect intestinal parasites in children living in some municipalities of the Cordillera province (Bolivia), where control programs started about 25 years ago. People and Methods – During 2011 a coproparasitological survey was carried out on 267 apparently healthy children 3-12-year-old, living in the municipalities of Cabezas, Lagunillas, Charagua, Cuevo, Camiri, Boyuibe and Gutierrez. Fecal samples were submitted to microscopic examination directly and after Ridley concentration. Parasites were identified on the basis of their morphological features, and samples positive to Blastocystis and Entamoeba histolytica complex were further analysed to identify the subtype and species, respectively, involved. Molecular diagnostics (PCR followed by sequencing, and nested PCR, respectively) were performed following protocols described by Bohm-Gloning et al (1997, Trop Med Int Health, 2: 771-8) and by Solaymani et al (2006, J Clin Microbiol, 44: 2258-61), Results - Intestinal protozoa and/or helminths were recovered in 69.7% of the samples, and multiple infections were observed in 39.7% of the subjects. No significant differences were observed between males and females, whereas a significant higher infection rate was recorded in 4-8-year-old children. The protozoon most commonly found was Giardia intestinalis (38.5%), followed by Entamoeba coli (37.8%) and Blastocystis spp. (15.7%). Other protozoa as Endolimax nana, Entamoeba hartmanni, E. histolytica/dispar/moskowskii, Iodamoeba butschlii and Chilomastix mesnili were also identified in 3.7%, 2.6%, 2.6%, 1.1% and 0.7% of the subjects, respectively. Coinfections E.coli-Giardia, E.coli-Blastocystis, E.coli-Blastocystis-Giardia were detected in 15.3%, 4.8%, and 2.9% of the children, respectively. Helminth eggs more often identified were those of Hymenolepis nana (5.6%), followed by those of Taenia spp (1.1%), Ascaris lumbricoides (0.7%), and hookworms (0.3%). A total of 15/42 (35.7%%) Blastocystis-microscopically positive samples yielded the expected amplicon of 1,100bp. Preliminary sequences obtained from 9 purified amplicons showed high identity (98%-100%) to homologous sequences of Blastocystis sp. subtypes 4 (n=3) and 5 (n=6) deposited in GenBank. Nested PCR identified 2 infections due to E. histolytica and 2 to E.dispar. Conclusions – Our findings, even if only based on children, indicate that implemented control programs (sanitary education included) resulted successful, as evidenced by the infection rate significantly lower than that observed in the same area in 1988 by Cancrini et al (Parassitologia, 30: 263-9). Geohelminths are almost absent, zoonotic opportunistic species like Balantidium coli and Cryptosporidium disappeared, and parasites like H. nana are strongly reduced, indicating a lower exposure to contamination with human faeces. The high prevalence of water/vegetable-transmitted protozoa suggests that hygienic conditions, mainly water supply, should be further improved. As for Blastocystis, subtype 4 we found is usually reported in humans, whereas subtype 5, yet found also in Italian population (Mattiucci et al, 2010, Parassitologia 52: 207), is thought to be specific to pig and cattle (Noel et al., 2005, J Clin Microbiol, 43:348-355). Unfortunately, E. histolytica is present and may represent a serious sanitary problem.