A decade of vector control activities: Progress and limitations of Chagas disease prevention in a region of Guatemala with persistent Triatoma dimidiata infestation.

INTRODUCTION: Chagas disease, a neglected tropical disease that affects millions of Latin Americans, has been effectively controlled in Guatemala after multiple rounds of indoor residual insecticide spraying (IRS). However, a few foci remain with persistent Triatoma dimidiata infestation. One such area is the municipality of Comapa, Department of Jutiapa, in the southeastern region of Guatemala, where control interventions appear less effective. We carried out three cross sectional entomological and serological surveys in Comapa to evaluate a decade of vector control activities. Baseline serological (1999) and entomological (2001-2) surveys were followed by three rounds of insecticide applications (2003-2005) and intermittent focal spraying of infested houses, until approximately 2012. Household inspections to determine entomological indices and construction materials were conducted in 2001, 2007 and 2011. Seroprevalence surveys were conducted in school-age children in 1999, 2007 and 2015, and in women of child bearing age (15-44 years) only in 2015. After multiple rounds of indoor residual sprayings (IRS), the infestation index decreased significantly from 39% (2001-2) to 27% (2011). Household construction materials alone predicted <10% of infested houses. Chagas seroprevalence in Comapa declined in school-aged children by 10-fold, from 10% (1999) to 1% (2015). However, seroprevalence in women of child bearing age remains >10%. CONCLUSION: After a decade of vector control activities in Comapa, there is evidence of significantly reduced transmission. However, the continued risk for vector-borne and congenital transmission pose a threat to the 2022 Chagas disease elimination goal. Systematic integrated vector control and improved Chagas disease screening and treatment programs for congenital and vector-borne disease are needed to reach the elimination goal in regions with persistent vector infestation.

A Knowledge, Attitudes and Practices Survey Conducted Three Years after Halting Ivermectin Mass Treatment for Onchocerciasis in Guatemala.

BACKGROUND: Mass drug administration (MDA) with ivermectin for onchocerciasis was provided in Guatemala's Central Endemic Zone (CEZ) over a 24 year period (1988-2011). Elimination of Onchocerca volvulus transmission was declared in 2015 after a three year post MDA surveillance period (2012-2014) showed no evidence of recrudescence. The purpose of the present study was to evaluate the knowledge, attitudes and practices (KAP) towards onchocerciasis and ivermectin among residents in the post endemic CEZ. A major interest in this study was to determine what community residents thought about the end of the ivermectin MDA program. METHODOLOGY/PRINCIPAL FINDINGS: A total of 148 interviews were conducted in November 2014 in four formerly hyperendemic communities using a standard questionnaire on smart phones. The majority (69%) of respondents knew that the MDA program had ended because the disease was no longer present in their communities, but a slight majority (53%) was personally unsure that onchocerciasis had really been eliminated. Sixty-three percent wanted to continue to receive ivermectin because of this uncertainty, or because ivermectin is effective against intestinal worms. Eighty-nine percent of respondents said that they would seek medical attention immediately if a family member had symptoms of onchocerciasis (especially the presence of a nodule), which is a finding very important for ongoing surveillance. CONCLUSIONS/SIGNIFICANCE: Many respondents wanted to continue receive ivermectin and more than half did not believe onchocerciasis had been eliminated. The ministry of health outreach services should be prepared to address ongoing concerns about onchocerciasis in the post endemic CEZ.

Culture and Dehydration: A Comparative Study of Caída de la Mollera (Fallen Fontanel) in Three Latino Populations.

A sunken soft-spot or fontanel is a sign for dehydration in infants. Around the world, folk illnesses, such as caída de la mollera in some Latin American cultures, often incorporate this sign as a hallmark of illness, but may or may not incorporate re-hydration therapies in treatment strategies. This report describes a study of lay descriptions of causes, symptoms, and treatments for caída de la mollera in three diverse Latin American populations. A mixed-methods approach was used. Representative community-based samples were interviewed in rural Guatemala, Guadalajara, Mexico, and Edinburgh, Texas, with a 132 item questionnaire on the causes, susceptibility, symptoms, and therapies for caída de la mollera. Cultural consensus analysis was used to estimate community beliefs about caída. Interviews conducted in rural Guatemala (n = 60), urban Mexico (n = 62), and rural Texas on the Mexican border (n = 61) indicated consistency in thematic elements within and among these three diverse communities. The high degree of consistency in the illness explanatory models indicated shared beliefs about caída de la mollera in each of the communities and a core model shared across communities. However, an important aspect of the community beliefs was that rehydration therapies were not widely endorsed. The consistency in explanatory models in such diverse communities, as well as the high degree of recognition and experience with this illness, may facilitate communication between community members, and health care providers/public health intervention planners to increase use of rehydration therapies for caída de la mollera. Recommendations for culturally informed and respectful approaches to clinical communication are provided.

Exposure of seasonal migrant workers to Onchocerca volvulus on coffee plantations in Guatemala.

Onchocerciasis (river blindness), which is close to being eliminated from Guatemala through semiannual administration of ivermectin, is still transmitted in one area of the country that coincidentally receives an annual influx of migrant workers to harvest coffee. Migrant workers generally are not included in semiannual ivermectin treatments, but if infected could serve as a reservoir. We report on two studies undertaken to measure the exposure to onchocerciasis (presence of IgG4 antibodies to a recombinant Onchocerca volvulus antigen, OV-16) among migrant workers. During two coffee harvest seasons, 170 migrant workers with a history of working in the disease-endemic area were tested and 1 (0.6%, 95% confidence interval = 0-3.2%) was seropositive. This low rate of exposure in migrant workers indicates that they are unlikely to play a significant role in transmission of onchocerciasis and may indicate that transmission in the last remaining disease-endemic area of Guatemala is decreasing significantly.

Women and war. What physicians should know.

Most of today's 1.7 million women veterans obtain all or most of their medical care outside the VA health care system, where their veteran status is rarely recognized or acknowledged. Several aspects of women's military service have been associated with adverse psychologic and physical outcomes, and failure to assess women's veteran status, their deployment status, and military trauma history could delay identifying or treating such conditions. Yet few clinicians know of women's military history--or of military service's impact on women's subsequent health and well being. Because an individual's military service may be best understood within the historical context in which it occurred, we provide a focused historical overview of women's military contributions and their steady integration into the Armed Forces since the War for Independence. We then describe some of the medical and psychiatric conditions associated with military service.

Population Biology of Pseudoperonospora humuli in Oregon and Washington.

Pseudoperonospora humuli populations from Oregon and Washington were analyzed for genetic variation using random amplified polymorphic DNA (RAPD) and DNA amplification fingerprinting (DAF) markers. The genetic structure of the Oregon and Washington populations differed considerably. There was little genetic diversity in Washington, with only five RAPD and six DAF groups detected among 40 isolates tested. One genotype was predominant in Washing-ton. In contrast, 18 RAPD and 34 DAF groups were found among the 40 isolates tested from Oregon. No unique band profile associated with host cultivar was observed. It is suggested that the distinct difference in population structure between the two geographic regions might be due to climatic differences resulting in a higher frequency of sexual reproduction of P. humuli in Oregon than in Washington.

A cross-cultural approach to the study of the folk illness nervios.

To systematically study and document regional variations in descriptions of nervios, we undertook a multisite comparative study of the illness among Puerto Ricans, Mexicans, Mexican Americans, and Guatemalans. We also conducted a parallel study on susto (Weller et al. 2002, Culture, Medicine and Psychiatry 26(4): 449-472), which allows for a systematic comparison of these illnesses across sites. The focus of this paper is inter- and intracultural variations in descriptions in four Latino populations of the causes, symptoms, and treatments of nervios, as well as similarities and differences between nervios and susto in these same communities. We found agreement among all four samples on a core description of nervios, as well as some overlap in aspects of nervios and susto. However, nervios is a much broader illness, related more to continual stresses. In contrast, susto seems to be related to a single stressful event.

Seroprevalence of Trypanosoma cruzi infection among school-age children in the endemic area of Guatemala.

In support of the National Program for Chagas Disease Control, we conducted a cross-sectional study to estimate the seroprevalence rate of Trypanosoma cruzi infection across the five Departments (Chiquimula, Jalapa, Zacapa, Jutiapa, and Santa Rosa) that are believed to comprise the entire principal endemic area in Guatemala. Also, so that the results could be used to identify areas of active transmission, we conducted the survey in school-aged children. We used an experimental enzyme-linked immunosorbent assay with blood samples obtained by finger prick to estimate the seroprevalence of T. cruzi. This assay has been previously tested and showed good sensitivity and specificity. Overall, the seropositivity rate for T. cruzi infection was 5.28% (235 of 4,450). Of 173 communities evaluated, 35 (20.23%) had a seropositive rate ranging from 10% to 45%. A number of parameters, including but not limited to living conditions, were examined for possible association with seropositivity. While there are several associations, the strongest association with seropositivity is living in a house with a thatch roof. The survey results will permit the Ministry of Health to stratify T. cruzi-endemic communities, enabling local health authorities to efficiently focus on vector control operations.

Regional variation in Latino descriptions of susto.

Susto, a folk illness not recognized by biomedical practitioners as a disease, is now formally part of the diagnostic classification system in psychiatry as a "culture-bound syndrome." Susto has been reported among diverse groups of Latin Americans, but most of those reports are several decades old and many were conducted in Indian communities. This study focuses on contemporary descriptions of susto and uses a cross-cultural, comparative design to describe susto in three diverse Latino populations. Mestizo/ladino populations were interviewed in Guatemala, Mexico, and south Texas. An initial set of open-ended interviews was conducted with a sample of "key" informants at each site to obtain descriptive information about susto. A structured interview protocol was developed for use at all three sites, incorporating information from those initial interviews. A second set of structured interviews was then conducted with a representative sample at each site. Results indicate a good deal of consistency in reports of what susto is: what causes it, its symptoms, and how to treat it. There appear to be, however, some notable regional variations in treatments and a difference between past descriptions and contemporary reports of etiology.

Incidence and Spatial Distribution of Viruses in Hop Gardens of Washington State.

The incidences of Hop latent virus (HpLV), Hop mosaic virus (HpMV), and American hop latent virus (AHLV), members of the genus Carlavirus, and Prunus necrotic ringspot virus and Apple mosaic virus, members of the genus Ilarvirus, were assessed for two hop cultivars, Horizon and Nugget, in Washington State. The spatial distribution of plants infected by the carlaviruses was assessed in two Horizon gardens in 2000 and one Nugget garden in 1993, 1994, and 1995. In the first Horizon garden (garden 1) and the Nugget garden, plants were separated by 2.1 m within and between rows. In these gardens, cultivation and the wide plant spacing discouraged contact between plants in either direction. In the second Horizon garden (garden 2), plants were separated by 4.3 m between rows and 1.0 m within rows. In all gardens, mechanical operations operated predominantly along rows; however, the closer plant spacing within rows in garden 2 permitted contact between adjacent plants within rows. In both Horizon gardens, the distribution of plants infected with HpMV was aggregated within rows. However, the distribution of plants infected with HpLV and AHLV was strongly influenced by contact between plants. In the Nugget garden, the distribution of plants infected by all three carlaviruses was autocorrelated within rows by 1995.

Efectos de los mosquiteros impregnados con permetrina sobre los vectores de la malaria en el norte de Guatemala / Effects of permethrin-impregnated bed nets on malaria vectors of Northern Guatemala

En un estudio con controles efectuado durante 16 meses en cuatro comunidades del norte de Guatemala, se evaluaron los efectos causados en los vectores de la malaria por mosquiteros impregnados con permetrina. Anopheles albimanus y An. vestitipennis son los vectores conocidos de la malaria en la zona. Cada casa se asignó a uno de tres grupos experimentales: las que recibieron mosquiteros impregnados con 500 mg de permetrina/m2, las que recibieron mosquiteros no tratados y aquellas en las que no se aplicaron medidas de intervención. El efecto de los mosquiteros tratados y no tratados sobre la abundancia, el comportamiento y la mortalidad de los mosquitos se determinó mediante recolecciones en el interior y el exterior de las viviendas de mosquitos que pican de noche, recoleciones matutinas con rociamientos de piretrina, inspección de la superficie de los mosquiteros para determinar la cantidad de mosquitos muertos y estudios mediante captura, liberación y recaptura. Se estimó la duración del efecto residual del insecticida en los mosquiteros tratados usando una forma modificada del ensayo biológico con conos de la OMS para empleo sobre el terreno. El contenido de piretrina en los mosquiteros se calculó mediante cromatografía de gases y líquidos. La observación más importante fue que se encontraron menos mosquitos reposando en las casas con mosquiteros tratados. Los mosquiteros tratados probablemente actuaban repeliendo y matando a los mosquitos vectores. Los estudios mediante captura, liberación y recaptura revelaron que los porcentajes de salida de las casas con mosquiteros tratados fueron más altos (94 por ciento) que los observados en las casas controles (72 por ciento), lo cual indica un efecto de repelencia. Sin embargo no se encontraron diferencias significativas entre las recolecciones de mosquitos que pican de noche en las casas con y sin mosquiteros tratados. Fue casi 20 veces más probable encontrar mosquitos anofelinos muertos en las superficies horizontales de los mosquiteros tratados que en las superficies similares de los mosquiteros no tratados. Los ennsayos biológicos indicaron que los mosquiteros impregnados con permetrina que no se lavaron retuvieron su acción onsecticida durante los 6 meses posteriores al tratamiento (AU)

Effects of Permethrin-impregnated bed nets on malaria vectors of northern Guatemala

8The authors evaluated the effects on malaria vectors of bed nets impregnated with permethrin over the course of a 16-month controlled study in four communities of Northern Guatemala. Anopheles albimanus and An. vestitipennis were the known malaria vectors in the area. Households were allocated to one of three experimental groups: those receiving bed nets impregnated with 500 mg/m2 of permethrim, those receiving untreated bed nets, and those where no intervention measures were taken. The impact of the treated and untreated bed nets on mosquito abundance, behavior, and mortality was determined by indoor/outdoor night-bite mosquito collections, morning pyrethrum spray collections, inspection of bed net surfaces for dead mosquitoes, and capture-release-recapture studies. The duration of the treated nets' residual insecticide effect was assessed by modified WHO cone fiel bioassays, and their pyrethrin content was estimated by gas-liquid chromatography analysis. The most important observation was that fewer mosquitoes were found to be resting in the households with treated bed nets. The treated nets probably functioned by both repelling and killing vector mosquitoes. Capture-release-recapture studies showed exit rated from houses with treated nets were higher (94 percent) than those from control houses (72 percent), a finding that suggests repellency. However, no significant differences were noted between the indoor night-bite mosquito collections at houses with and without treated nets. The horizontal surfaces of treated bed nets were nearly 20 times more likely to contain dead anopheline mosquitoes than were the comparable surfaces of untreated nets. The bioassays indicated that unwashed permethrin-impregnated bed nets retained their insecticidal activity for 6 months after treatment

Effects of Permethrin-impregnated bed nets on malaria vectors of northern Guatemala

8The authors evaluated the effects on malaria vectors of bed nets impregnated with permethrin over the course of a 16-month controlled study in four communities of Northern Guatemala. Anopheles albimanus and An. vestitipennis were the known malaria vectors in the area. Households were allocated to one of three experimental groups: those receiving bed nets impregnated with 500 mg/m2 of permethrim, those receiving untreated bed nets, and those where no intervention measures were taken. The impact of the treated and untreated bed nets on mosquito abundance, behavior, and mortality was determined by indoor/outdoor night-bite mosquito collections, morning pyrethrum spray collections, inspection of bed net surfaces for dead mosquitoes, and capture-release-recapture studies. The duration of the treated nets' residual insecticide effect was assessed by modified WHO cone fiel bioassays, and their pyrethrin content was estimated by gas-liquid chromatography analysis. The most important observation was that fewer mosquitoes were found to be resting in the households with treated bed nets. The treated nets probably functioned by both repelling and killing vector mosquitoes. Capture-release-recapture studies showed exit rated from houses with treated nets were higher (94 percent) than those from control houses (72 percent), a finding that suggests repellency. However, no significant differences were noted between the indoor night-bite mosquito collections at houses with and without treated nets. The horizontal surfaces of treated bed nets were nearly 20 times more likely to contain dead anopheline mosquitoes than were the comparable surfaces of untreated nets. The bioassays indicated that unwashed permethrin-impregnated bed nets retained their insecticidal activity for 6 months after treatment

This article will also be published in Spanish in the BOSP. Vol. 117, 1994

Efectos de los mosquiteros impregnados con permetrina sobre los vectores de la malaria en el norte de Guatemala / Effects of permethrin-impregnated bed nets on malaria vectors of Northern Guatemala

En un estudio con controles efectuado durante 16 meses en cuatro comunidades del norte de Guatemala, se evaluaron los efectos causados en los vectores de la malaria por mosquiteros impregnados con permetrina. Anopheles albimanus y An. vestitipennis son los vectores conocidos de la malaria en la zona. Cada casa se asignó a uno de tres grupos experimentales: las que recibieron mosquiteros impregnados con 500 mg de permetrina/m2, las que recibieron mosquiteros no tratados y aquellas en las que no se aplicaron medidas de intervención. El efecto de los mosquiteros tratados y no tratados sobre la abundancia, el comportamiento y la mortalidad de los mosquitos se determinó mediante recolecciones en el interior y el exterior de las viviendas de mosquitos que pican de noche, recoleciones matutinas con rociamientos de piretrina, inspección de la superficie de los mosquiteros para determinar la cantidad de mosquitos muertos y estudios mediante captura, liberación y recaptura. Se estimó la duración del efecto residual del insecticida en los mosquiteros tratados usando una forma modificada del ensayo biológico con conos de la OMS para empleo sobre el terreno. El contenido de piretrina en los mosquiteros se calculó mediante cromatografía de gases y líquidos. La observación más importante fue que se encontraron menos mosquitos reposando en las casas con mosquiteros tratados. Los mosquiteros tratados probablemente actuaban repeliendo y matando a los mosquitos vectores. Los estudios mediante captura, liberación y recaptura revelaron que los porcentajes de salida de las casas con mosquiteros tratados fueron más altos (94 por ciento) que los observados en las casas controles (72 por ciento), lo cual indica un efecto de repelencia. Sin embargo no se encontraron diferencias significativas entre las recolecciones de mosquitos que pican de noche en las casas con y sin mosquiteros tratados. Fue casi 20 veces más probable encontrar mosquitos anofelinos muertos en las superficies horizontales de los mosquiteros tratados que en las superficies similares de los mosquiteros no tratados. Los ennsayos biológicos indicaron que los mosquiteros impregnados con permetrina que no se lavaron retuvieron su acción onsecticida durante los 6 meses posteriores al tratamiento (AU)

Se publica en inglés en el Bull. PAHO. Vol. 28(2), 1994