Interruption of Onchocerca volvulus transmission in Northern Venezuela

Particle and Fibre Toxicology

María E Grillet⁴  Hortencia Frontado³  Alfredo Domínguez-Vázquez¹  Vimerca Olivero²  Rafael Borges²  Harland Schuler²  Jacinto Convit² 

[1] Onchocerciasis Elimination Program for the Americas, Guatemala City, Guatemala;Servicio Autónomo Instituto de Biomedicina & Servicio Regionales de Dermatología Sanitaria, Ministerio del Poder Popular para la Salud, Caracas, Venezuela;Instituto de Altos Estudios “Dr. Arnoldo Gabaldón”, Ministerio del Poder Popular para la Salud, Maracay, Venezuela;Laboratorio de Biología de Vectores y Parásitos, Instituto de Zoología y Ecología Tropical, Facultad de Ciencias, Universidad Central de Venezuela, Apartado Postal 47072, Caracas 1041-A, Venezuela

关键词: Venezuela;    Ivermectin;    Interruption;    Simulium metallicum;    Onchocerciasis;   

Others  :  1225300
DOI  :  10.1186/1756-3305-6-289

 received in 2013-08-07, accepted in 2013-10-02,  发布年份 2013

【 摘 要 】

Background

Onchocerciasis is caused by Onchocerca volvulus and transmitted by Simulium species (black flies). In the Americas, the infection has been previously described in 13 discrete regional foci distributed among six countries (Brazil, Colombia, Ecuador, Guatemala, Mexico and Venezuela) where more than 370,000 people are currently considered at risk. Since 2001, disease control in Venezuela has relied on the mass drug administration to the at-risk communities. This report provides empirical evidence of interruption of Onchocerca volvulus transmission by Simulium metallicum in 510 endemic communities from two Northern foci of Venezuela, after 10–12 years of 6-monthly Mectizan® (ivermectin) treatment to all the eligible residents.

Methods

In-depth entomologic and epidemiologic surveys were serially conducted from 2001–2012 in selected (sentinel and extra-sentinel) communities from the North-central (NC) and North-east (NE) onchocerciasis foci of Venezuela in order to monitor the impact of ivermectin treatment.

Results

From 2007–2009, entomological indicators in both foci confirmed that 0 out of 112,637 S. metallicum females examined by PCR contained L₃ infection in insect heads. The upper bound of the 95% confidence intervals of the infective rate of the vector reached values below 1% by 2009 (NC) and 2012 (NE). Additionally, after 14 (NC) and 22 (NE) rounds of treatment, the seasonal transmission potential (±UL CIs) of S. metallicum was under the critical threshold of 20 L₃ per person per season. Serological analysis in school children < 15 years-old demonstrated that 0 out of 6,590 individuals were harboring antibodies to Ov-16. Finally, epidemiological surveys made during 2010 (NC) and 2012 (NE) showed no evidence of microfilariae in the skin and eyes of the population.

Conclusions

These results meet the WHO criteria for absence of parasite transmission and disease morbidity in these endemic areas which represent 91% of the population previously at-risk in the country. Consequently, the two Northern foci are currently under post-treatment onchocerciasis surveillance status in Venezuela.

【 授权许可】

   
2013 Convit et al.; licensee BioMed Central Ltd.

【 图 表 】

Figure 1.

Figure 2.

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