Michele Spinicci1, Fabio Macchioni2, Antonia Mantella1, Simona Gabrielli3, Mimmo Roselli1, David Rojo Mayaregua4, Joaquín Monasterio Pinckert5, Herlan Gamboa Barahona6, Grover Adolfo Paredes7, Percy Halkyer8, Gabriella Cancrini3, Piero Olliaro9, Antonio Montresor10, Alessandro Bartoloni1. 1. Dipartimento di Medicina Sperimentale e Clinica, Università degli Studi di Firenze, Firenze, Italy. 2. Dipartimento di Scienze Veterinarie, Università degli Studi di Pisa, Pisa, Italy. 3. Dipartimento di Sanità Pubblica e Malattie Infettive, Università di Roma Sapienza, Roma, Italy. 4. Escuela de Salud del Chaco Tekove Katu, Gutierrez, Plurinational State of Bolivia. 5. Servicio Departamental de Salud (SEDES) de Santa Cruz, Santa Cruz, Plurinational State of Bolivia. 6. Facultad Integral del Chaco, Universidad Autonoma Gabriel René Moreno, Camiri, Plurinational State of Bolivia. 7. Ministerio de Salud, Programa Nacional de Zoonosis, La Paz, Plurinational State of Bolivia. 8. Immunization, Pan-American Health Organization, La Paz, Plurinational State of Bolivia. 9. Special Programme for Research and Training in Tropical Diseases (WHO/TDR), WHO, Geneva, Switzerland. 10. Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland.
Abstract
OBJECTIVES: The prevalence of Strongyloides stercoralis infections is grossly underestimated because infections go mostly undetected, although they can persist for a lifetime due to the auto-infective cycle. In the Bolivian Chaco, the prevalence of soil-transmitted nematodes dropped dramatically in the past 25 years, but the mebendazole used for preventive chemotherapy has no effect on S. stercoralis. Meanwhile, the prevalence of intestinal protozoan infections remains unchanged. We compared S. stercoralis seroprevalence in rural communities of the Bolivian Chaco from 1987 to 2013. METHODS: Sera collected during two previous serosurveys, conducted in the Chaco region in 1987 and 2013, were tested for S. stercoralis using a commercial assay (Bordier-ELISA, Bordier Affinity Products, Switzerland). RESULTS: Overall, 355 sera were analysed, 122 from the 1987 survey and 233 from the 2013 survey. Seropositivity for S. stercoralis was significantly more prevalent in 1987 (19/122, 16% in 1987 vs. 15/233, 6% in 2013, P = 0.006), accounted for by a drop from 17% to 3% in people under 26 years of age. Multivariate analysis showed a significant association between seropositivity for S. stercoralis and age in the 2013 population (OR 1.03 for each one-year increase, 95%CI 1.00-1.05, P = 0.04), but none in 1987. CONCLUSIONS: The significant reduction in S. stercoralis seroprevalence in Bolivian Chaco cannot be explained by preventive chemotherapy or improved social-sanitary conditions. As the drop is seen in younger generations, it is consistent with little transmission occurring. However, the risk of transmission still exists, as prevalence is persistently high in older individuals, who present a potential reservoir due to the lifelong nature of S. stercoralis infections.
OBJECTIVES: The prevalence of Strongyloides stercoralis infections is grossly underestimated because infections go mostly undetected, although they can persist for a lifetime due to the auto-infective cycle. In the Bolivian Chaco, the prevalence of soil-transmitted nematodes dropped dramatically in the past 25 years, but the mebendazole used for preventive chemotherapy has no effect on S. stercoralis. Meanwhile, the prevalence of intestinal protozoan infections remains unchanged. We compared S. stercoralis seroprevalence in rural communities of the Bolivian Chaco from 1987 to 2013. METHODS: Sera collected during two previous serosurveys, conducted in the Chaco region in 1987 and 2013, were tested for S. stercoralis using a commercial assay (Bordier-ELISA, Bordier Affinity Products, Switzerland). RESULTS: Overall, 355 sera were analysed, 122 from the 1987 survey and 233 from the 2013 survey. Seropositivity for S. stercoralis was significantly more prevalent in 1987 (19/122, 16% in 1987 vs. 15/233, 6% in 2013, P = 0.006), accounted for by a drop from 17% to 3% in people under 26 years of age. Multivariate analysis showed a significant association between seropositivity for S. stercoralis and age in the 2013 population (OR 1.03 for each one-year increase, 95%CI 1.00-1.05, P = 0.04), but none in 1987. CONCLUSIONS: The significant reduction in S. stercoralis seroprevalence in Bolivian Chaco cannot be explained by preventive chemotherapy or improved social-sanitary conditions. As the drop is seen in younger generations, it is consistent with little transmission occurring. However, the risk of transmission still exists, as prevalence is persistently high in older individuals, who present a potential reservoir due to the lifelong nature of S. stercoralis infections.
Authors: Rubén Mercado; Maria Isabel Jercic; Sergio Alcayaga; Fabiana M de Paula; Marlene T Ueta; Julia M Costa-Cruz Journal: Rev Inst Med Trop Sao Paulo Date: 2007 Jul-Aug Impact factor: 1.846
Authors: Zeno Bisoffi; Dora Buonfrate; Antonio Montresor; Ana Requena-Méndez; Jose Muñoz; Alejandro J Krolewiecki; Eduardo Gotuzzo; Maria Alejandra Mena; Peter L Chiodini; Mariella Anselmi; Juan Moreira; Marco Albonico Journal: PLoS Negl Trop Dis Date: 2013-05-09
Authors: Dora Buonfrate; Ana Requena-Mendez; Andrea Angheben; Jose Muñoz; Federico Gobbi; Jef Van Den Ende; Zeno Bisoffi Journal: BMC Infect Dis Date: 2013-02-08 Impact factor: 3.090