A Critical Assessment of Officially Reported Chagas Disease Surveillance Data in Mexico

OBJECTIVE

Chagas disease, a disease caused by Trypanosoma cruzi, disproportionately affects poor people throughout Latin America. In Mexico, assessments of officially reported burden have not been previously reported. To evaluate discontinuity between surveillance data and data from other sources, we used data from the Mexican Ministry of Health to describe the distribution of reported Chagas disease over time in Mexico and compare it with estimates from the literature.

METHODS

We summarized age and sex differences for Chagas cases and mortality for 1995-2013 and 1982-2010, respectively. We examined the spatial distribution of Chagas disease over time with respect to disease burden. We further compared officially reported figures with estimates from the literature.

RESULTS

Among 6,494 officially reported cases, rates of Chagas disease were highest in adults aged 25-44 years (47.3%). Mortality was highest in adults aged ≥45 years (423/495, 85.5%). The data indicated increasing temporal trends for incidence and mortality. The greatest burden occurred in southern states, with increasing spatial distribution over time. Fewer than 900 cases and 40 deaths were officially reported annually, in contrast to estimates from the literature of approximately 69,000 new cases and 25,000 deaths annually.

CONCLUSION

While increasing trends in officially reported data have been observed, large discrepancies in case estimates compromise our understanding of Chagas disease epidemiology. Reported cases based on current practices are not enough to correctly assess the Chagas disease burden and spatial distribution in Mexico. Understanding the true epidemiology of this disease will lead to more focused and successful control and prevention strategies to decrease disease burden.

Population-based prevalence of malaria among pregnant women in Enugu State, Nigeria: the Healthy Beginning Initiative

BACKGROUND

Malaria adversely affects pregnant women and their fetuses or neonates. Estimates of the malaria burden in pregnant women based on health facilities often do not present a true picture of the problem due to the low proportion of women delivering at these facilities in malaria-endemic regions.

METHODS

Data for this study were obtained from the Healthy Beginning Initiative using community-based sampling. Self-identified pregnant women between the ages of 17-45 years were recruited from churches in Enugu State, Nigeria. Malaria parasitaemia was classified as high and low based on the malaria plus system.

RESULTS

Of the 2069 pregnant women for whom malaria parasitaemia levels were recorded, over 99 % tested positive for malaria parasitaemia, 62 % showed low parasitaemia and 38 % high parasitaemia. After controlling for confounding variables, odds for high parasitaemia were lower among those who had more people in the household (for every one person increase in a household, OR = 0.94, 95 % CI 0.89-0.99).

CONCLUSION

Results of this study are consistent with hospital-based estimates of malaria during pregnancy in southeastern Nigeria. Based on the high prevalence of malaria parasitaemia in this sample, education on best practices to prevent malaria during pregnancy, and resources in support of these practices are urgently needed.

Awareness and support of release of genetically modified "sterile" mosquitoes, Key West, Florida, USA

After a dengue outbreak in Key West, Florida, during 2009–2010, authorities, considered conducting the first US release of male Aedes aegypti mosquitoes genetically modified to prevent reproduction. Despite outreach and media attention, only half of the community was aware of the proposal; half of those were supportive. Novel public health strategies require community engagement.

Risk of Mortality According to Body Mass Index and Body Composition Among Postmenopausal Women

Obesity, often defined as a body mass index (BMI; weight (kg)/height (m)(2)) of 30 or higher, has been associated with mortality, but age-related body composition changes can be masked by stable BMI. A subset of Women's Health Initiative participants (postmenopausal women aged 50-79 years) enrolled between 1993 and 1998 who had received dual-energy x-ray absorptiometry scans for estimation of total body fat (TBF) and lean body mass (LBM) (n = 10,525) were followed for 13.6 (standard deviation, 4.6) years to test associations between BMI, body composition, and incident mortality. Overall, BMI ≥35 was associated with increased mortality (adjusted hazard ratio (HR) = 1.45, 95% confidence interval (CI): 1.16, 1.82), while TBF and LBM were not. However, an interaction between age and body composition (P < 0.001) necessitated age stratification. Among women aged 50-59 years, higher %TBF increased risk of death (HR = 2.44, 95% CI: 1.38, 4.34) and higher %LBM decreased risk of death (HR = 0.41, 95% CI: 0.23, 0.74), despite broad-ranging BMIs (16.4-69.1). However, the relationships were reversed among women aged 70-79 years (P < 0.05). BMI did not adequately capture mortality risk in this sample of postmenopausal women. Our data suggest the clinical utility of evaluating body composition by age group to more robustly assess mortality risk among postmenopausal women.

Sociocultural and Victimization Factors That Impact Attitudes Toward Intimate Partner Violence Among Kenyan Women

This study investigates the association between acceptance of intimate partner violence (IPV) and reported IPV victimization among Kenyan women, taking into consideration select sociocultural factors that may also influence acceptance of IPV. Data from a nationally representative, cross-sectional, household survey conducted between November 2008 and February 2009 in Kenya were analyzed. Hierarchical multiple regression was conducted to estimate the effect of select sociodemographic characteristics and reported IPV victimization on acceptance of IPV. The results showed that while both sociodemographic characteristics and reported IPV victimization were significantly associated with IPV acceptance, sociocultural factors had a greater impact. Programs aimed at empowering women and culturally competent IPV prevention strategies may be the key elements to reducing IPV.

Post Outbreak Review: Dengue Preparedness and Response in Key West, Florida

Dengue is the most prevalent mosquito-borne viral infection. Recent outbreaks in the southern United States illustrate the risk of reemergence. The first autochthonous cases since 1934 in Key West, FL, occurred in 2009-2010. We conducted a survey in 2012 with decision makers instrumental to the control of the outbreak to 1) determine their awareness of the multiple strategies used to control the outbreak and 2) assess their perceptions of the relative effectiveness of these strategies. An online survey was delivered to a predefined list of decision makers from multiple sectors to better understand dengue preparedness and response. Thirty-six out of 45 surveys were returned for an 80% response rate. Results indicate the need to focus prevention strategies on educational campaigns designed to increase population awareness of transmission risk. Respondents remain concerned about future dengue transmission risk in Key West and lack of resources to respond.

Knowledge and Beliefs about Dengue Transmission and Their Relationship with Prevention Practices in Hermosillo, Sonora

Background

Dengue is an emerging threat in the U.S.-Mexico border region. Transmission has regularly occurred in Sonora, MX since 1982 but it was not until 2014 that cities directly on the Arizona-Sonora border had local transmission. One of the closest urban areas to have regular seasonal transmission is Hermosillo, SN, MX. Developing a better understanding of the knowledge and perceptions of dengue in close geographic proximity to the border can identify areas to target for prevention and control measures.

Methods

We conducted focus groups in six neighborhoods in Hermosillo, SN, MX; three with high-dengue transmission and three with lower transmission. Awareness of dengue and experience with dengue was common.

Results

In all focus groups, discussants reported knowing someone personally who had past dengue infection. We further identified several key ways that the perceptions of dengue transmission could influence the effectiveness of dengue control campaigns. First, there was confusion about how dengue is transmitted. While people associated dengue with mosquitoes, multiple modes of transmission were perceived including direct person-to-person transmission. In one focus group, discussants indicated a stigma surrounding dengue infection. The necessity to maintain cleanliness in their households was identified as a primary strategy to fight dengue; however, participants also noted the limited impact and their actions may have on transmission if there is lack of community support or governmental infrastructure to control neighboring and public spaces.

Conclusion

As dengue risk increases in the border region, more efforts should be made to clearly convey the single mode of transmission of dengue to avoid the development of stigma. More coordinated efforts should be made to not only control but also prevent dengue.

The role of ethnicity and travel on Hepatitis A vaccination coverage and disease incidence in Arizona at the United States-Mexico Border

BACKGROUND

Hepatitis A (HAV) incidence has decreased in the United States, yet regional disparities persist. The role of international travel has become increasingly important in HAV transmission. We compared the relative burden of HAV in border and non-border regions in Arizona and examined the role of travel in sustaining HAV transmission.

METHODS

HAV vaccination coverage was calculated by age and region, using Arizona State Immunization Information System data. Incidence, demographics, and risk factors of cases reported through Arizona's infectious disease surveillance system between 2006 and 2011 were analyzed.

RESULTS

Hepatitis A incidence was higher in the border region of Arizona. Compared with the rest of Arizona, one-dose coverage in children<15 years was lower in the border region until 2008. Second dose coverage was lower in the border region, particularly among Spanish speakers. International travel among cases was generally high; however, in the border region cases were more likely to visit Mexico or South/Central America (94% vs. 80%, P value = 0.01) and be Hispanic (68% vs. 42%, P value = 0.0003).

CONCLUSIONS

Rates of HAV continue to be higher in the Arizona border region; the risk appears particularly high among Hispanics with recent travel in the Americas. Border surveillance should be emphasized, along with vaccination of all travelers, to continue to decrease and control HAV.

A country bug in the city: urban infestation by the Chagas disease vector Triatoma infestans in Arequipa, Peru

BACKGROUND

Interruption of vector-borne transmission of Trypanosoma cruzi remains an unrealized objective in many Latin American countries. The task of vector control is complicated by the emergence of vector insects in urban areas.

METHODS

Utilizing data from a large-scale vector control program in Arequipa, Peru, we explored the spatial patterns of infestation by Triatoma infestans in an urban and peri-urban landscape. Multilevel logistic regression was utilized to assess the associations between household infestation and household- and locality-level socio-environmental measures.

RESULTS

Of 37,229 households inspected for infestation, 6,982 (18.8%; 95% CI: 18.4 - 19.2%) were infested by T. infestans. Eighty clusters of infestation were identified, ranging in area from 0.1 to 68.7 hectares and containing as few as one and as many as 1,139 infested households. Spatial dependence between infested households was significant at distances up to 2,000 meters. Household T. infestans infestation was associated with household- and locality-level factors, including housing density, elevation, land surface temperature, and locality type.

CONCLUSIONS

High levels of T. infestans infestation, characterized by spatial heterogeneity, were found across extensive urban and peri-urban areas prior to vector control. Several environmental and social factors, which may directly or indirectly influence the biology and behavior of T. infestans, were associated with infestation. Spatial clustering of infestation in the urban context may both challenge and inform surveillance and control of vector reemergence after insecticide intervention.

Development of clinical immunity to malaria in highland areas of low and unstable transmission

In highland areas of unstable, low malaria transmission, the extent to which immunity to uncomplicated malaria develops with age and intermittent parasite exposure has not been well characterized. We conducted active surveillance for clinical malaria during April 2003-March 2005 in two highland areas of western Kenya (Kapsisiywa and Kipsamoite). In both sites, annual malaria incidence was significantly lower in persons ≥ 15 years of age than in persons < 5 years of age (Kapsisiywa: incidence = 382.9 cases/1,000 persons among persons < 1-4 years of age versus 135.1 cases/1,000 persons among persons ≥ 15 years of age; Kipsamoite: incidence = 233.0 cases/1,000 persons in persons < 1-4 years of age versus 43.3 cases/1,000 persons in persons ≥ 15 years of age). In Kapsisiywa, among persons with malaria, parasite density and axillary body temperature were also significantly lower in persons ≥ 15 years of age than in persons < 5 years of age. Even in highland areas of unstable and low malaria transmission, age is associated with development of clinical immunity to malaria.

The changing epidemiology of hepatitis A in Arizona following intensive immunization programs (1988-2007)

INTRODUCTION

Arizona had the highest hepatitis A incidence of any U.S. state during 1987-1997. In 1995, the first hepatitis A vaccines became available in the U.S. A series of hepatitis A vaccination policies and recommendations were implemented in 1996-2006. Our objective was to examine the shifting epidemiologic patterns in hepatitis A in Arizona from 1988 to 2007.

METHODS

Passive surveillance reports to the Arizona Department of Health Services were used to compare hepatitis A rates by age, race/ethnicity and geographic area, before and after widespread vaccination. Reported risk factors and possible sources of infection were compared for two time periods. Age-adjusted incidence during three periods was mapped.

RESULTS

Overall hepatitis A incidence in Arizona fell from 58 cases per 100,000 in 1988 to 2 per 100,000 in 2007. The proportion of reported cases among children dropped from 62% in 1994-1995 to 32% in 2006-2007. Racial/ethnic disparities between American Indians and non-Hispanic White populations have been eliminated. The geographic distribution of cases within the state has shifted. Earlier cases were likely to report contact with another hepatitis A case or childcare facilities, while later cases indicated recent international travel.

CONCLUSION

A major shift in the overall burden of hepatitis A and hepatitis A transmission has occurred in Arizona since the widespread implementation of immunization policies and the concomitant rise in vaccination rates in the state. Current transmission has shifted to older age groups and disparities by race/ethnicity are now highest in Hispanic populations. Future strategies to further reduce hepatitis A transmission may require broadening recommendations to include general adult populations without previous vaccination history.

The effect of policy changes on hepatitis A vaccine uptake in Arizona children, 1995-2008

OBJECTIVE

In 1995, the first hepatitis A vaccines became available for use. At that time, Arizona had the highest hepatitis A incidence of all 50 states. During that same time period, the Arizona State Immunization Information System (ASIIS) was created to collect information on all immunizations given in the state. Four state-level hepatitis A vaccination policies were enacted according to Centers for Disease Control and Prevention recommendations and local initiatives from 1996 to 2005. Our primary objective was to assess the impact of these policies on vaccine uptake in children.

METHODS

Immunization records from ASIIS were used to calculate yearly coverage of children with at least one reported hepatitis A vaccination between 1995 and 2008. Proportions vaccinated were calculated by age group (12-23 months, 24-59 months, 5-9 years, 10-14 years, and 15-19 years) for three regions: Maricopa County; Apache and Navajo counties; and the remaining 12 Arizona counties, which were grouped as one to reflect different target groups for the four policies examined. We calculated percent changes from before and after each policy implementation.

RESULTS

Significantly different percent changes were detected among the three regions that related to the four policies implemented. Percent change in uptake was consistently higher in the regions that were targeted for that specific policy.

CONCLUSIONS

Analysis of ASIIS data revealed a major effect of hepatitis A policy recommendations on vaccine uptake in Arizona. Targeting high-risk populations through vaccine recommendations and child care entry requirements was highly successful in achieving higher vaccination coverage.

Health status of southern Arizona border counties: a Healthy Border 2010 midterm review

OBJECTIVE

The region on the United States (US) side of the US-Mexico border consists of 44 counties in four states; populations on both sides of the border have similar health problems. Healthy Border 2010: An Agenda for Improving Health on the US-Mexico Border (HB 2010) is a binational agenda of health promotion and disease prevention for individuals in the region. This study reports on the health status of the four southern Arizona border counties.

METHODS

Data on health indicators for Cochise, Pima, Santa Cruz, and Yuma Counties were collected from the Arizona Department of Health Services Vital Records and Statistics. Progress was calculated as a percentage made toward or away from the 2010 target. Comparisons were made between the border counties and Arizona.

RESULTS

Progress toward the HB 2010 targets varied among the border counties. All border counties made progress toward the targets with the cervical cancer, hepatitis A, and teenage birthrate objectives. Most border counties moved toward the goals for breast cancer, diabetes mortality, tuberculosis, motor vehicle crashes, infant mortality from congenital abnormalities, and prenatal care. Border counties moved away from the target with the human immunodeficiency virus and infant mortality objectives.

CONCLUSIONS

Assessment of the HB 2010 objectives provided a comprehensive description of the health status of the population. Although the southern Arizona border counties have shown improvement in some areas, monitoring is still needed to identify the disparities that remain.

Environmental, socio-demographic and behavioural determinants of malaria risk in the western Kenyan highlands: a case-control study

OBJECTIVE

To identify risk factors for uncomplicated malaria in highland areas of East Africa at higher risk of malaria epidemics, in order to design appropriate interventions.

METHODS

Prospective, population-based, case-control study in the Nandi Hills, a highland area of western Kenya, to identify environmental, sociodemographic and behavioural factors associated with clinical malaria. Data were collected using field observation, a structured questionnaire, and a global positioning system device.

RESULTS

We interviewed 488 cases of slide-confirmed malaria and 980 age-matched controls. Multivariate analyses associated higher malaria risk with living <250 m of a forest [OR = 3.3 (95% CI 1.5, 7.1)], <250 m of a swamp [2.8 (1.3, 5.9)], <200 m of maize fields [2.0 (1.2, 3.4)], in the absence of trees <200 m [1.6 (1.2, 2.2)], on flat land [1.6 (1.2, 2.2)], in houses without ceilings [1.5 (1.1, 2.2)], in houses with a separate kitchen building [1.8 (1.4, 2.3)] and in households where the female household head had no education [1.9 (1.1, 3.1)]. Travelling out of the study site [2.2 (1.2, 4.1)] was also associated with increased risk. CONCLUSIONS; In this East African highland area, risk of developing uncomplicated malaria was multifactorial with a risk factor profile similar to that in endemic regions. Households within close proximity to forest and swamp borders are at higher risk of malaria and should be included in indoor residual spraying campaigns.

Microscopy underestimates the frequency of Plasmodium falciparum infection in symptomatic individuals in a low transmission highland area

In an area with unstable malaria transmission, detection of Plasmodium falciparum infection in 379 symptomatic individuals was assessed by microscopy and three polymerase chain reaction (PCR) methodologies. P. falciparum infection was detected in 25% of patients by microscopy, 37% by nested PCR, 41% by merozoite surface protein-2 (MSP-2) PCR, and 45% by a ligase detection reaction-fluorescent microsphere assay (LDR-FMA). Of the 64 individuals who were LDR-FMA positive, microscopy negative and did not receive treatment, 8 (12.5%) had persistent symptoms and returned for treatment. Malaria attributable fraction (MAF) in symptomatic individuals was 14.6% by microscopy (95% confidence interval [CI] = 6.6-21.8%) and 28.2% by nested PCR (95% CI = 17.9-37.2%). In this highland area, P. falciparum infection in symptomatic individuals is detected more frequently by PCR than microscopy, and most frequently by LDR-FMA. P. falciparum infection appears to resolve without treatment in most LDR-FMA-positive, microscopy-negative individuals, but is persistent in a subset of these individuals and requires treatment.

Topography-derived wetness indices are associated with household-level malaria risk in two communities in the western Kenyan highlands

BACKGROUND

Transmission of Plasmodium falciparum generally decreases with increasing elevation, in part because lower temperature slows the development of both parasites and mosquitoes. However, other aspects of the terrain, such as the shape of the land, may affect habitat suitability for Anopheles breeding and thus risk of malaria transmission. Understanding these local topographic effects may permit prediction of regions at high risk of malaria within the highlands at small spatial scales.

METHODS

Hydrologic modelling techniques were adapted to predict the flow of water across the landscape surrounding households in two communities in the western Kenyan highlands. These surface analyses were used to generate indices describing predicted water accumulation in regions surrounding the study area. Households with and without malaria were compared for their proximity to regions of high and low predicted wetness. Predicted wetness and elevation variables were entered into bivariate and multivariate regression models to examine whether significant associations with malaria were observable at small spatial scales.

RESULTS

On average, malaria case households (n = 423) were located 280 m closer to regions with very high wetness indices than non-malaria "control" households (n = 895) (t = 10.35, p < 0.0001). Distance to high wetness indices remained an independent predictor of risk after controlling for household elevation in multivariate regression (OR = 0.93 [95% confidence interval = 0.89-0.96] for a 100 m increase in distance). For every 10 m increase in household elevation, there was a 12% decrease in the odds of the house having a malaria case (OR = 0.88 [0.85-0.90]). However, after controlling for distance to regions of high predicted wetness and the community in which the house was located, this reduction in malaria risk was not statistically significant (OR = 0.98 [0.94-1.03]).

CONCLUSION

Proximity to terrain with high predicted water accumulation was significantly and consistently associated with increased household-level malaria incidence, even at small spatial scales with little variation in elevation variables. These results suggest that high wetness indices are not merely proxies for valley bottoms, and hydrologic flow models may prove valuable for predicting areas of high malaria risk in highland regions. Application in areas where malaria surveillance is limited could identify households at higher risk and help focus interventions.

Malaria hotspot areas in a highland Kenya site are consistent in epidemic and non-epidemic years and are associated with ecological factors

Background

Malaria epidemics in highland areas of East Africa have caused considerable morbidity and mortality in the past two decades. Knowledge of "hotspot" areas of high malaria incidence would allow for focused preventive interventions in resource-poor areas, particularly if the hotspot areas can be discerned during non-epidemic periods and predicted by ecological factors.

Methods

To address this issue, spatial distribution of malaria incidence and the relationship of ecological factors to malaria incidence were assessed in the highland area of Kipsamoite, Kenya, from 2001–2004.

Results

Clustering of disease in a single geographic "hotspot" area occurred in epidemic and non-epidemic years, with a 2.6 to 3.2-fold increased risk of malaria inside the hotspot, as compared to outside the area (P < 0.001, all 4 years). Altitude and proximity to the forest were independently associated with increased malaria risk in all years, including epidemic and non-epidemic years.

Conclusion

In this highland area, areas of high malaria risk are consistent in epidemic and non-epidemic years and are associated with specific ecological risk factors. Ongoing interventions in areas of ecological risk factors could be a cost-effective method of significantly reducing malaria incidence and blunting or preventing epidemics, even in the absence of malaria early warning systems. Further studies should be conducted to see if these findings hold true in varied highland settings.