Browsing by Subject "Peru"

American cutaneous leishmaniasis (CL) is a severely understudied and neglected“disease of poverty” widespread throughout Peru. Transmission dynamics of CL are complex, requiring sandfly vectors and mammalian reservoir hosts to maintain the pathogen in a local environment whereby incidental hosts (people) can become infected. We employed a One-Health approach to understand CL transmission in rapidly changing region of northern Peru. We describe the characteristics of 529 CL positive patients from four participating clinics. Using conditional logistic regression, we assessed risk factors of CL for residents of small urban areas through a matched case-control study with 63 patients who had visited one of the same clinics for CL (cases) or other medical reasons (controls). We later enrolled 343 households as part of a community based study occurring in 15 urban and rural areas of Soritor. We found 256 positive humans (n= 914) as tested via the Montenegro Skin Test; we found 11 positive dogs (n = 236) via an immunofluorescence antibody test. Our results suggest that most- if not all- of CL transmission is occurring in rural areas and that urban women and urban children engage in many high risk activities typically attributed to men. We find evidence that prevalence of past infection is highest among rural residents and men. We believe dogs are unlikely Leishmania reservoirs in either rural or urban settings. It remains unknown if the high number of MST positive children in rural areas is a result of peridomestic or intradomestic transmission.

Background: Understanding the multifactorial causes of anemia on a population level is important for creating effective interventions that mitigate poor health outcomes associated with anemia, particularly in regions where these rates are highly elevated. This study aims to quantify the relative prevalence of iron deficiency anemia, anemia of inflammation, and micronutrient deficiency anemia within 2 – 11 year olds in Madre de Dios (MDD), Peru, where anemia rates are estimated to be between 40 and 50%. It further aims to assess varying risk factors for given etiologies by community type, particularly as many communities in this region experience varied exposure to gold-mining related methylmercury. Methods: Eight communities along the Madre de Dios River, within the Peruvian Amazon, were selected in order to screen 2 – 11 year olds for anemia. Those qualifying as anemic were invited to provide venous blood samples for iron level, inflammation, and nutrition biomarker analyses in order to differentiate between these anemia etiologies. Health history and household characteristics were gathered in survey format, and analyzed in relation to gathered biomarkers. Results: Overall anemia prevalence (18.5%) was significantly decreased from previous studies. 14.9% were iron deficient, 12.8% showed signs of inflammation, and 12.8% were Vitamin B12 deficient. Anemia prevalence varied significantly by sex. Risk factors for anemia did not vary significantly by community type, other than increased annual income in urban and mining communities, and a reduced likelihood for having been born prematurely within mining communities. Conclusions: Peru’s multi-sectoral approach to reducing anemia has shown promising results in MDD. Health determinant variations have proven largely insignificant for anemia outcomes within the screened communities.

Cervical cancer is the second leading cause of death for women worldwide with 85% of deaths occurring in low and middle-income countries, despite being both preventable and treatable if detected early enough. The burden of disease persists primarily due to a lack of access to early diagnostics and significant proportion lost to follow-up. In Peru specifically, the mortality rates of cervical cancer are among the highest in the world with an annual incidence of 48.2 per 100,000.

To provide low-cost and accessible colposcopy while maintaining image quality, the point of care tampon like (Pocket) digital colposcope is being developed in the Tissue Optical Spectroscopy (TOpS) Lab at Duke University. As part of the ongoing Pocket colposcope development and validation, the Generation 3 Pocket colposcope was tested for concordance to the standard-of-care Goldway SLC-2000 digital colposcope in a pilot study conducted in Lima, Peru. The goal of this study is to demonstrate equivalence in clinical diagnostic performance of the Generation 3 Pocket colposcope versus the standard-of-care digital colposcope.

100 patients were enrolled under the IRB approved study protocol Pro00052865. Paired images of cervices were collected with the standard digital colposcope and the Pocket colposcope for each patient using acetic acid and Lugol’s iodine as contrast agents. Biopsies were taken as part of standard-of-care whenever required. The paired images were blinded by device, randomized, and sent with an electronic survey to three Duke affiliated physicians who are highly trained in colposcopy.

The primary outcome measured was level of agreement using an unweighted kappa statistic between 1) overall diagnosis and 2) Reid Colposcopic Index scores for the Generation 3 Pocket colposcope and Goldway colposcope. The secondary outcome measured was sensitivity, specificity, positive predictive value, and negative predictive value.

The percent agreement for all physicians combined between systems for the overall diagnosis was 83.78% with a kappa of 0.5786 and p-value of <0.0000, and the percent agreement for the Reid Colposcopic Index score comparison was 72.3% with a kappa of 0.4366 and p-value of <0.0000 indicating strong concordance. Both systems performed similarly when compared to gold-standard pathology, with level of agreement ~66% and a kappa statistic of ~0.3, and p-values <0.0000.

The Generation 3 Pocket colposcope performed similarly to the standard Goldway colposcope and can be used to increase access to colposcopy, thereby reducing the burden of cervical cancer morbidity and mortality in Peru and around the world.

Mercury (Hg) is a globally circulating heavy metal released through both natural and anthropogenic sources. The largest anthropogenic source of mercury to the global atmosphere is artisanal and small-scale gold mining (ASGM). During the ASGM process, miners add elemental mercury to large quantities of sediment or soil in order to create gold-mercury amalgams that separate alluvial gold from the remaining geological host material. Miners then heat the amalgam using a blowtorch or similar device to separate the mercury and gold, exposing themselves to mercury vapor and releasing mercury to the environment. Following amalgam heating, mercury can deposit into aquatic ecosystems. There, anaerobic microorganisms can convert mercury to methylmercury (MeHg), a potent neurotoxin that rapidly accumulates in aquatic food webs. A high concentration of MeHg in fish poses serious human health risks, especially to pregnant women and children.

In Peru’s Region of Madre de Dios (MDD), mercury use for ASGM is widespread due to increasing global demand for gold. This region in the tropical Amazon is one of the world’s most biodiverse ecosystems and home to more than 150,000 Indigenous and non-Indigenous people, 40% of whom live below the poverty level. Recently, people living in the region have become more aware of negative impacts of Hg pollution through popular press. However, there is lack of controlled scientific studies to examine the environmental impacts of Hg from ASGM and subsequent exposures to surrounding communities.

This dissertation addresses four questions in order to better understand how mercury from ASGM impacts environmental health in Madre de Dios: (1) How is mercury distributed along the Madre de Dios River in areas of active ASGM activity, and what is the risk for mercury exposure to downstream communities? (2) How does land use change associated with ASGM activity affect soil-mediated mercury transport in the Colorado River, Madre de Dios, Peru? (3) Can sulfurized carbon be manufactured in a feasible way for developing countries and used to capture mercury during ASGM amalgam burning? (4) What is the mercury methylation potential of easy-to-manufacture spent, sulfurized carbon sorbents?

Despite significant information on the direct health impacts of mercury to ASGM miners, the impact of mercury contamination on downstream communities has not been well characterized, particularly in Madre de Dios. In this area, ASGM has increased significantly since 2000 and has led to substantial political and social controversy. The second chapter of this dissertation examines the spatial distribution and transport of mercury through the Madre de Dios River with distance from ASGM activity. It also characterizes risks for dietary mercury exposure to local residents who depend on fish from the river. River sediment, suspended solids from the water column, and fish samples were collected in 2013 at 62 sites near 17 communities over a 560 km stretch of the Madre de Dios River and its major tributaries. In areas downstream of know ASGM activity, mercury concentrations in sediment, suspended solids and fish within the Madre de Dios River were elevated relative to locations upstream of mining. Fish tissue mercury concentrations were observed at levels representing a public health threat, with greater than one-third of carnivorous fish exceeding the international health standard of 0.5 mg/kg. This research demonstrates that communities located hundreds of kilometers downstream of ASGM activity, including children and indigenous populations who may not be involved in mining, are at risk of dietary mercury exposure that exceed acceptable body burdens.

This research involved extensive field sampling in an active mining region and indicated suspended particulate transport may be an important source of mercury from mining areas to downstream communities. Chapter three of this research focused on understanding how land use changes can influence soil and sediment transport from mining regions. Within the MDD, a large portion of mining in concentrated within the Colorado River watershed. In the Colorado River watershed, mining and deforestation have increased dramatically since the 1980s, largely concentrated in the Puquiri subwatershed. Field sampling in Feb 2015 identified a strong correlation between Hg and suspended solids concentrations, with especially high suspended solids concentrations downstream of ASGM activity. This supported the hypothesis that Mercury transport in this region is facilitated by soil mobilization and runoff. In order to understand how ASGM activity in the Puquiri affects sediment mobilization from the watershed over time, we employed a watershed-scale soil mobilization model using satellite imagery from 1986 to 2014. The model estimated that soil mobilization in the Colorado River watershed increased by 2.5 times during the time period, and increased by six times in the Puquiri subwatershed, leading to between 10 and 60 kg of mercury mobilized in 2014. If deforestation continues at its current exponential rate through 2030, soil and heavy metal mobilization may increase by five times. This research shows that deforestation associated with ASGM in the Colorado River watershed can exacerbate soil mobilization and mercury contamination. While the impacts of mercury and deforestation are often considered separately, here we studied how deforestation associated with ASGM in the Madre de Dios region can significantly increase soil mobilization and mercury transport to downstream communities.

With a substantial portion of mercury releases coming from a non-industrialized process in developing countries, low-cost and low-tech mercury capture is becoming increasingly necessary. While impregnated activated carbon sorbents are well studied for mercury-capture in developed countries and large industrialized settings, there exist few suitable low-cost alternatives for mercury capture from artisanal and small-scale gold mining (ASGM) in developing countries. Chapter four sought to develop an easy-to-manufacture carbon sorbent using elemental sulfur and activated carbon or hardwood-based biochar for potential use during ASGM gold-amalgam heating. Consumer-grade sulfur powder was melted on granular activated carbon or hardwood biochar in a process feasible for a cook stove setting. Activated carbon and biochar were successfully sulfurized to more than 5% sulfur by weight using powdered, elemental sulfur. The sorbent products were tested for elemental mercury sorption from an air gas stream at room temperature. The sulfurized activated carbon achieved higher elemental mercury adsorption capacity in air stream (500 μg Hg m-3, 2 L min-2) relative to unsulfurized activated carbon and sulfurized biochar. Sorption isotherms were used to examine the sorption mechanism, and indicated that likely a pseudo first order reaction was occurring. This research provides a possible option for mercury control by modifying established mercury capture technologies to be easy to manufacture, locally available, and less hazardous to produce.

In Chapter 5 of this research, the sulfurized sorbents were examined further to understand methylation potential in sediment slurries. Anaerobic sediment slurries were constructed to examine methylmercury (MeHg) production of spent sorbents. Five sorbent types with approximately 10 mg/kg Hg each were added to slurries at 5 % by mass. Dissolved mercury was used as a control to simulate atmospheric deposition or highly reactive mercury. After a 5 d incubation at room temperature, MeHg production was ten times greater with low-technology sulfurized sorbents as compared to activated carbon or biochar alone. Sulfurized sorbents leached significantly more mercury than their non-sulfurized counterparts during desorption experiments and led to greater dissolved mercury concentrations. This research shows that low-cost mercury-contaminated sorbents can have unintended consequences with increased MeHg production and potential for more harm to local communities than atmospheric release.

Mercury releases from ASGM are expected to grow, leading to higher concentrations of mercury in the atmosphere that may affect ecosystems throughout the globe. Understanding the importance of mercury from ASGM to toxicity and accumulation requires in depth research on mercury transformations and MeHg production associated with ASGM. This research examines mercury distribution and transport from ASGM active regions. It identifies that deforestation, erosion, and particulate transport play important roles in overall mercury transport, leading to hazardous mercury concentrations downstream of ASGM activity. Effective point-of-use mercury capture technologies would dramatically decrease the mass of mercury released to the environment. The final chapters of this research serve as a proof of concept for using sulfurized activated carbon for mercury capture in developing countries.

Our research team has built strong relationships with several governmental and non-governmental organizations in Peru who will aid in distributing information. This research will provide invaluable environmental health information to residents, inform political intervention, and reveal a new potential avenue for low-cost mercury control.

Non-essential trace metals (lead, mercury, arsenic, and cadmium) are ubiquitous in our environment and have overlapping routes of exposure, yet mixed trace metal exposures are rarely considered in epidemiological studies. Instead, research often follows a single research question that focuses on a single trace metal of concern and does not incorporate potential co-exposures. The published literature of artisanal small-scale mining in the Amazon is a prime example as it has predominantly focused on mercury exposure, due to its use in the mining process. Once exposures of concern are identified, further studies evaluate health outcomes; however, the health effects cannot be accurately determined without accounting for co-exposures. This verification is becoming more important as there is a growing recognition that mixed trace metal exposures are more common than previously believed.To address the prevalence of mixed trace metal exposures and their health effects in the Peruvian Amazon region of Madre de Dios, I use epidemiological data from the COhorte de NAcimiento de MAdre de Dios (CONAMAD) birth cohort study (2018-Present), and two cross-sectional epidemiological studies (Amarakaeri Communal Reserve study (ACR, 2015), and Etiology and Toxic Metals study (EATM, 2018)). CONAMAD collected survey data along with maternal and cord blood samples at birth, which were processed for minerals and trace metals. The cross-sectional studies collected venous blood for trace metal analysis and hair samples for total hair mercury. Blood samples from the ACR were also processed for amino acids. In-depth demographic and health survey data were collected in all three studies. Structural equation models and random mixed effect models were used to evaluate research questions. The cross-sectional studies demonstrate a high correlation of lead and mercury exposure in communities that rely on wild fish and wild game as protein sources, which is prevalent throughout the Amazon. Consuming a meal of wild game resulted in an estimated lead dose of 500 µg, with those who eat wild game (Yes/No) associated with 1.41 µg/dL (95% CI: 1.20 – 1.70) higher blood lead levels compared to those who do not. This furthers the notion that mixed exposures are likely more common than previously believed. Mixed exposures target the same toxicological pathway, which may lead to synergistic or antagonistic effects. My research found that lead disrupts the arginine pathway and is associated with increased blood pressure. Mercury exposure was a modifier of the arginine pathway, with high blood mercury levels changing the effect of global arginine bioavailability from 17.16 (95% CI: 9.09 – 25.84) to -14.17 (95% CI: -31.88 - -0.33) on systolic blood pressure. Interestingly, mercury was not directly associated with the arginine pathway. Results from the birth cohort demonstrate the importance of nutrition and prenatal care for fetal development, which had a large positive effect on birthweight and gestational age. However, even low maternal lead exposure had detrimental effects on fetal health. A 1% increase in maternal blood lead was associated with a shorter gestational age of 0.05 days (β: -0.75, 95% CI: -1.51 - -0.13), even with the CONAMAD birth cohort having lower blood lead levels than other birth cohorts. There is a need for an integrated approach of nutritional and exposure assessments to better understand neonatal health outcomes.

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Background: Peru had more COVID-related deaths per capita than any other country. Given its relative wealth as an Upper Middle Income Country, Peru did not receive many COVID vaccine donations through COVAX, and challenges directly negotiating for vaccines with pharmaceutical companies delayed Peru’s initial response. However, once vaccines were procured, Peru successfully initiated wide-spread vaccination campaigns. This study was done to understand Peru’s unique COVID challenges and successes and aims to explore barriers and enablers of Peru’s pandemic response to offer lessons for the scale-up of vaccinations, health innovations, and pandemic response capacity in Peru, Latin America, and globally. Methods: 31 semi-structured in- depth interviews were conducted in Lima, Peru with 35 individuals from public, private, academia, healthcare, and civil society sectors that worked in diverse geographies across Peru. Participants were recruited through purposeful and snowball sampling via WhatsApp, based on the inclusion criteria of being involved in Peru’s COVID-19 pandemic response and preparedness (i.e., with vaccine procurement and distribution, emergency health innovations, and community responses). Ethics approval was received from the Duke University Campus Institutional Review Board. Written and verbal consent was obtained from participants before each interview. A qualitative content analysis is currently being done on the interview transcripts. Afterwards a force field analysis will be applied to understand which factors most negatively and positively impacted Peru’s pandemic response capacity. Results: Preliminary findings from the 31 interviews indicate political instability, cross-sector competition, a fragmented health system, and limited medical resource manufacturing and regulations limited Peru’s pandemic response. However, previous experience with vaccination campaigns, community-based support, and cross-sector collaboration influenced effective COVID vaccine distribution and vaccination levels. Conclusion: Peru experienced some small-scale effective COVID response measures, but these were overshadowed by large-scale systemic and political issues, hindering Peru’s pandemic response. This study explores economic, cultural, political, and social factors that impacted Peru’s COVID response, and includes diverse perspectives from various sectors and geographies, increasing the validity and generalizability of findings. However, future studies should include equal representation of sectors and geographies, as most participants represent the public sector and worked in Lima.

While the Madre de Dios department of Peru has the nation's highest leishmaniasis incidence, limited research on the disease and its sand fly vector exists in the region. Considering the diverse and adaptive nature of sand flies, understanding vector ecology is essential to directing leishmaniasis control efforts. This study addresses this need by investigating the following aims: 1) describe sand fly abundance and biodiversity in communities along the Madre de Dios River; 2) identify environmental and socio-demographic factors associated with sand fly abundance and biodiversity in these communities; and 3) examine ecological risk factors associated with leishmaniasis in the communities. In order to accomplish these aims, the research team collected sand flies, obtained leishmaniasis case data, conducted community and household surveys, measured soil samples and studied land cover data in communities along the Madre de Dios River. We compared sand fly abundance, sand fly biodiversity and leishmaniasis incidence with soil chemistry, socio-demographic and land cover measures. We ran negative binomial regressions and Poisson regressions to investigate bivariate relationships between dependent and independent variables. We developed a multivariate model that predicts greater potential vector and non-vector abundance in areas with greater forest coverage, lower infrastructure indices and lower soil pH. This study provides an important overview of endemic sand fly fauna in Madre de Dios and presents an initial description of factors associated with sand fly populations in the region.

A multilevel analysis of malaria risk factors was conducted using data gathered from community-wide surveillance along the Iquitos-Mazan Road and Napo River in Loreto, Peru. In total, 1650 individuals nested within 338 households nested within 18 communities were included in the study. Personal travel (Odds Ratios [OR] 2.48; 95% Confidence Interval [CI] = 1.46, 4.21) and other house member's malaria statuses (OR = 2.54; 95% CI = 1.49, 4.32) were all associated with increased odds in having a malaria episode. Having a large household (>5 individuals) (OR = 0.33; 95% CI = 0.12, 0.93), presence of a community health post / secondary school (OR =0.26; 95% CI = 0.08, 0.80) and church (OR = 0.33; 95% CI = 0.30, 0.78) were associated with lower odds of having a malaria episode. Malaria clustering was evident as 54% of the malaria burden occurred in only 6% of the households surveyed.

Background: Plasmodium vivax and Plasmodium falciparum contribute a high burden of disease in the Peruvian Amazon. Migration is an important risk factor for malaria, as travel along the river systems accounts for the vast majority of movement within this region. This travel creates networks of transmission that allows individuals who travel to contract malaria as well as generating transmission across communities by repeatedly reintroducing the parasite into different areas, which can complicate control efforts.

Methods: Surveyors visited homes of participants three times a week to carry out active surveillance between July 2006 and October 2009. For participants returning from travel, data were collected on destination and duration away, which was used to define a typology for migrant populations. Incidence rates of malaria and migration typology characteristics were assessed through Negative Binomial regression models and migration rates with hydrological factors by logistic regression models.

Results: A cohort of 2,202 participants from 402 families were followed for three years and categorized by the average number of annual trips taken. High-frequency and low-frequency migrant populations reported 9.7 (IRR 7.59 (95% CI:.381, 13.160)) and 4.1 (IRR 2.89 (95% CI: 1.636, 5.099)) times more P. vivax cases than those considered non-migrants and 30.7 (IRR 32.42, (95% CI: 7.977, 131.765)) and 7.4 (IRR 7.44 (95% CI: 1.783, 31.066)) times more P. falciparum cases, respectively. Among high frequency migrants, males were at a 1.20 (95% CI: 0.872, 1.641) increased risk compared to female high frequency migrants. Working in agriculture, logging, and fishing were at 1.02, 1.36, 1.93 increased risk for P. vivax and 2.46, 2.35, 2.03 times increased risk of P. falciparum compared to those in non-migrant positions. However, the greatest occupation related risk was attributed to high frequency migrants employed in manual labor within their community. This group was at 2.45 (95% CI: 1.113, 5.416) times higher risk than non-employed low frequency migrants. Travel to lakes, rivers, and streams were 2.36, 1.81, and 1.95 times as many P. vivax and 1.36, 1.34, and 2.08 P. falciparum cases, respectively, compared to travel to communities. More migration episodes were recorded in the dry season, however, the seven day rolling mean streamflow was positively correlated with migration events (OR 1.25 (95% CI: 1.138, 1.368)).

Conclusions: Migration is a key risk factor for malaria; however, it alone does not characterize the distribution on risk within the migrant community. This study gives information about particular population groups to target control efforts.