Sustaining communicable disease elimination efforts in the Americas in the wake of COVID-19.

The COVID-19 pandemic has disrupted implementation of health interventions and set back priority programs aiming to control and eliminate communicable diseases. At the same time, the pandemic has opened up opportunities to expedite innovations in health service delivery to increase effectiveness and position health on the development and political agendas of leaders and policy makers. In this context, we present an integrated, sustainable approach to accelerate elimination of more than 35 communicable diseases and related conditions in the region of the Americas. The Elimination Initiative promotes a life-course, person-centred approach based on four dimensions - preventing new infections, ending mortality and morbidity, and preventing disability - and four critical lines of action including strengthening health systems integration and service delivery, strengthening health surveillance and information systems, addressing environmental and social determinants of health, and furthering governance, stewardship, and finance. We present key actions and operational considerations according to each line of action that countries can take advantage of to further advance disease elimination in the region.

Prevalencia e intensidad de la infección por geohelmintos y prevalencia de la malaria en escolares de El Salvador / Prevalence and intensity of infection by soil-transmitted helminths and prevalence of malaria among schoolchildren in El Salvador

Introducción. El Salvador no cuenta con datos actualizados de prevalencia en menores de 15 años de la infección por helmintos transmitidos por contacto con el suelo. Además, al ser uno de los países en las Américas que reporta un número bajo de casos de malaria, se considera que su eliminación allí es factible. Objetivo. Determinar la prevalencia y la intensidad de la infección por geohelmintos y la prevalencia de Plasmodium spp. en escolares de 8 a 10 años de El Salvador. Materiales y métodos. Se hizo un estudio de corte transversal en las cinco zonas eco-epidemiológicas del país (planicie costera, depresión central, cadena volcánica, cadena costera y zona montañosa). La presencia de geohelmintiasis se estudió en 1.325 estudiantes y, la de malaria, en 152. Se utilizó la técnica de Kato-Katz para la detección de geohelmintos, y para el diagnóstico de la malaria, una prueba rápida, el estudio mediante microscopía y la prueba de reacción en cadena de la polimerasa. Resultados. La prevalencia total de geohelmintiasis fue de 7,9 % (IC 95% 6,6-9,5). En la planicie costera fue de 14,9 % (IC 95% 10,9-19,7); en la depresión central, de 9,4 % (IC 95% 6,5-13,3); en la cadena volcánica, de 6,6 % (IC 95% 4,2-10,5); en la cadena costera, de 5,9 % (IC 95% 3,8-9,4), y en la cadena montañosa, de 2,6 % (IC 95% 1,4-5,7). La proporción de infección de gran intensidad debida a cualquiera de las especies de geohelmintos fue de 0,3 %. No se encontraron escolares infectados con Plasmodium spp. Conclusión. La prevalencia de geohelmintos fue baja y la especie más prevalente fue Trichuris trichiura . La intensidad de la infección debida a cualquiera de las especies de geohelmintos fue leve (<1 %). Los factores de riesgo asociados a la infección por geohelmintos fueron la defecación al aire libre, no usar calzado y vivir en la planicie costera.

Introduction: El Salvador does not have recent data on the prevalence of infection with soil-transmitted helminths among children aged under 15 years of age. As one of the countries in the Americas that reports few malaria cases, eradication of this disease from El Salvador is considered to be feasible. Objective: To determine the prevalence and intensity of infection by soil-transmitted helminths, as well as the prevalence of Plasmodium spp. in schoolchildren aged 8-10. Materials and methods: A cross-sectional study was carried out in each of the five eco-epidemiological zones of the country (coastal plain, central basin, volcanic range, coastal range and mountain zone). In all 1,325 students we studied the presence of geohelminthiasis, with 152 of them also being tested for malaria. The Kato-Katz technique was used to detect geohelminths while diagnosis of malaria was performed using the rapid diagnostic test, microscopy and polymerase chain reaction. Results: The overall prevalence of geohelminthiasis was 7.9% (95%CI 6.6-9.5%). Values for the five eco-epidemiological zones were as follows: coastal plain, 14.9% (95%CI 10.9-19.7%); central plateau, 9.4% (95%CI 6.5-13.3%); volcanic range, 6.6% (95%CI 4.2-10.5%); coastal range, 5.9% (95%CI 3.8-9.4%), and mountain zone, 2.6% (95%CI 1.4-5.7%). The overall rate of high intensity infection with any of the geohelminth species was 0.3%. No schoolchildren were found infected with Plasmodium spp. by any of the three diagnostic techniques used. Conclusion: Prevalence of geohelminths was low and Trichuris trichiura was the predominant species. Intensity of infection with any of the species of geohelminths was light (<1%). The risk factors associated with infection by soil-transmitted helminths were defecation in the open air, being barefoot and living in coastal areas.

[Prevalence and intensity of infection by soil-transmitted helminths and prevalence of malaria among schoolchildren in El Salvador]. / Prevalencia e intensidad de la infección por geohelmintos y prevalencia de la malaria en escolares de El Salvador.

INTRODUCTION: El Salvador does not have recent data on the prevalence of infection with soil-transmitted helminths among children aged under 15 years of age. As one of the countries in the Americas that reports few malaria cases, eradication of this disease from El Salvador is considered to be feasible. OBJECTIVE: To determine the prevalence and intensity of infection by soil-transmitted helminths, as well as the prevalence of Plasmodium spp. in schoolchildren aged 8-10. MATERIALS AND METHODS: A cross-sectional study was carried out in each of the five eco-epidemiological zones of the country (coastal plain, central basin, volcanic range, coastal range and mountain zone). In all 1,325 students we studied the presence of geohelminthiasis, with 152 of them also being tested for malaria. The Kato-Katz technique was used to detect geohelminths while diagnosis of malaria was performed using the rapid diagnostic test, microscopy and polymerase chain reaction. RESULTS: The overall prevalence of geohelminthiasis was 7.9% (95%CI 6.6-9.5%). Values for the five eco-epidemiological zones were as follows: coastal plain, 14.9% (95%CI 10.9-19.7%); central plateau, 9.4% (95%CI 6.5-13.3%); volcanic range, 6.6% (95%CI 4.2-10.5%); coastal range, 5.9% (95%CI 3.8-9.4%), and mountain zone, 2.6% (95%CI 1.4-5.7%). The overall rate of high intensity infection with any of the geohelminth species was 0.3%. No schoolchildren were found infected with Plasmodium spp. by any of the three diagnostic techniques used. CONCLUSION: Prevalence of geohelminths was low and Trichuris trichiura was the predominant species. Intensity of infection with any of the species of geohelminths was light (<1%). The risk factors associated with infection by soil-transmitted helminths were defecation in the open air, being barefoot and living in coastal areas.

Prevalence and intensity of soil-transmitted helminthiasis, prevalence of malaria and nutritional status of school going children in honduras.

BACKGROUND: Many small studies have been done in Honduras estimating soil-transmitted helminthiasis (STH) prevalence but a country-wide study was last done in 2005. The country has the highest burden of malaria among all Central American countries. The present study was done to estimate country-wide STH prevalence and intensity, malaria prevalence and nutritional status in school going children. METHODS AND FINDINGS: A cross-sectional study was conducted following PAHO/WHO guidelines to select a sample of school going children of 3rd to 5th grades, representative of ecological regions in the country. A survey questionnaire was filled; anthropometric measurements, stool sample for STH and blood sample for malaria were taken. Kato-Katz method was used for STH prevalence and intensity and rapid diagnostic tests, microscopy, and polymerase chain reaction (PCR) were used for malaria parasite detection. A total of 2554 students were studied of which 43.5% had one or more STH. Trichuriasis was the most prevalent (34%) followed by ascariasis (22.3%) and hookworm (0.9%). Ecological regions II (59.7%) and VI (55.6%) in the north had the highest STH prevalence rates while IV had the lowest (10.6%). Prevalence of one or more high intensity STH was low (1.6%). Plasmodium vivax was detected by PCR in only 5 students (0.2%), all of which belonged to the same municipality; no P. falciparum infection was detected. The majority of children (83%) had normal body mass index for their respective age but a significant proportion were overweight (10.42%) and obese (4.35%). CONCLUSIONS: Biannual deworming campaigns would be necessary in ecological regions II and VI, where STH prevalence is >50%. High prevalence of obesity in school going children is a worrying trend and portends of future increase in obesity related diseases. Malaria prevalence, both symptomatic and asymptomatic, was low and provides evidence for Honduras to embark on elimination of the disease.

Update on the mapping of prevalence and intensity of infection for soil-transmitted helminth infections in Latin America and the Caribbean: a call for action.

It is estimated that in Latin America and the Caribbean (LAC) at least 13.9 million preschool age and 35.4 million school age children are at risk of infections by soil-transmitted helminths (STH): Ascaris lumbricoides, Trichuris trichiura and hookworms (Necator americanus and Ancylostoma duodenale). Although infections caused by this group of parasites are associated with chronic deleterious effects on nutrition and growth, iron and vitamin A status and cognitive development in children, few countries in the LAC Region have implemented nationwide surveys on prevalence and intensity of infection. The aim of this study was to identify gaps on the mapping of prevalence and intensity of STH infections based on data published between 2000 and 2010 in LAC, and to call for including mapping as part of action plans against these infections. A total of 335 published data points for STH prevalence were found for 18 countries (11.9% data points for preschool age children, 56.7% for school age children and 31.3% for children from 1 to 14 years of age). We found that 62.7% of data points showed prevalence levels above 20%. Data on the intensity of infection were found for seven countries. The analysis also highlights that there is still an important lack of data on prevalence and intensity of infection to determine the burden of disease based on epidemiological surveys, particularly among preschool age children. This situation is a challenge for LAC given that adequate planning of interventions such as deworming requires information on prevalence to determine the frequency of needed anthelmintic drug administration and to conduct monitoring and evaluation of progress in drug coverage.

Soil-transmitted helminthiasis in Latin America and the Caribbean: modelling the determinants, prevalence, population at risk and costs of control at sub-national level.

We present an example of a tool for quantifying the burden, the population in need of intervention and resources need to contribute for the control of soil-transmitted helminth (STH) infection at multiple administrative levels for the region of Latin America and the Caribbean (LAC). The tool relies on published STH prevalence data along with data on the distribution of several STH transmission determinants for 12,273 sub-national administrative units in 22 LAC countries taken from national censuses. Data on these determinants was aggregated into a single risk index based on a conceptual framework and the statistical significance of the association between this index and the STH prevalence indicators was tested using simple linear regression. The coefficient and constant from the output of this regression was then put into a regression formula that was applied to the risk index values for all of the administrative units in order to model the estimated prevalence of each STH species. We then combine these estimates with population data, treatment thresholds and unit cost data to calculate total control costs. The model predicts an annual cost for the procurement of preventive chemotherapy of around US$ 1.7 million and a total cost of US$ 47 million for implementing a comprehensive STH control programme targeting an estimated 78.7 million school-aged children according to the WHO guidelines throughout the entirety of the countries included in the study. Considerable savings to this cost could potentially be made by embedding STH control interventions within existing health programmes and systems. A study of this scope is prone to many limitations which restrict the interpretation of the results and the uses to which its findings may be put. We discuss several of these limitations.

The Pan American Health Organization's role and perspectives on the mapping and modeling of the neglected tropical diseases in Latin America and the Caribbean: an overview.

The Pan American Health Organization (PAHO), which functions as the regional office for the Americas of the World Health Organization, is committed to provide technical cooperation to countries to update the epidemiological information available for mapping and modelling of the neglected tropical diseases (NTDs), a set of diseases mainly caused by parasites affecting people living in low socioeconomic and favourable environmental conditions. This communication discusses PAHO's role and perspectives in the use of mapping and modelling of these diseases with a view to promote its use in the development and implementation of integrated, inter-programmatic and inter-sectoral plans for the prevention, control or elimination of the NTDs and other infectious diseases related to poverty.

Self-avoiding walks and connective constants in small-world networks.

Long-distance characteristics of small-world networks have been studied by means of self-avoiding walks (SAW's). We consider networks generated by rewiring links in one- and two-dimensional regular lattices. The number of SAW's u(n) was obtained from numerical simulations as a function of the number of steps n on the considered networks. The so-called connective constant, mu=lim(n-->infinity)u(n)/u(n-1), which characterizes the long-distance behavior of the walks, increases continuously with disorder strength (or rewiring probability p). For small p, one has a linear relation mu=mu(0)+ap, mu(0) and a being constants dependent on the underlying lattice. Close to p=1 one finds the behavior expected for random graphs. An analytical approach is given to account for the results derived from numerical simulations. Both methods yield results agreeing with each other for small p, and differ for p close to 1, because of the different connectivity distributions resulting in both cases.