INVESTIGACIÓN ORIGINAL ORIGINAL RESEARCH
Conocimientos y prácticas relacionados con el síndrome pulmonar por hantavirus en un conglomerado de comunidades japonesas en Argentina
Kuniaki Suzuki1; Luciano E. Mutinelli
Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, Argentina
OBJECTIVES: To provide information on hantavirus pulmonary syndrome (HPS) knowledge and practices among a cluster of the rural Japanese communities near La Plata in central Ar gentina, an area with confirmed HPS cases. Particular emphasis was placed on testing the hy pothesis that there would be differences between household use of HPS prevention measures based on the head-of-household's knowledge of HPS.
METHODS: A questionnaire was designed in three sections: (1) household demographic char acteristics, (2) HPS knowledge, and (3) HPS preventive measures. Questionnaires were given to the household head or other adult representing the household at an HPS prevention semi nar sponsored by the Japanese Association of La Plata in February 2007. Total HPS knowl edge scores were dichotomized into high (equal to or more than the median knowledge score) and low (less than the median). Differences between the two household groups were catego rized, according to the degree of HPS knowledge, and analyzed.
RESULTS: The 86 households that responded accounted for about 72% of the total study households in the area. The median knowledge score of 5 (range: 0-9, of 10) divided the study households into two groups: high knowledge score group (n = 40) and low knowledge score group (n = 46). The findings suggest an association between a household's accurate HPS knowledge and its respective use of HPS preventive measures.
CONCLUSION: The findings of the study have important implications for taking further steps toward improved HPS management and prevention strategies.
Key words: Hantavirus pulmonary syndrome, rodentia, ethnic group and health, Argentina.
OBJETIVOS: Documentar los conocimientos y las prácticas relacionadas con el síndrome pulmonar por hantavirus (SPH) en un conglomerado de comunidades rurales japonesas cerca de La Plata, en la parte central de Argentina, una zona con casos confirmados de SPH. Se hizo hincapié especial en probar la hipótesis de que habría diferencias en el empleo de medidas preventivas contra el SPH en los hogares según el nivel de conocimientos del jefe de familia sobre este síndrome.
MÉTODOS: Se diseñó un cuestionario con tres secciones: a) características demográficas del núcleo familiar, b) conocimientos sobre el SPH y c) medidas preventivas contra el SPH. Los cuestionarios se aplicaron a los jefes de familia o a algún adulto que representara al núcleo familiar durante un seminario sobre prevención del SPH patrocinado por la Asociación Japonesa de La Plata en febrero de 2007. El conocimiento sobre el SPH se clasificó según su puntuación total en alto (igual o mayor que la mediana de las puntuaciones) y bajo (menor que la mediana). Se analizaron las diferencias entre los dos grupos según el grado de conocimientos sobre el SPH.
RESULTADOS: Respondieron representantes de 86 hogares, aproximadamente 72% del total de la zona. La mediana de la puntuación fue de 5 (entre 0 y 9 en una escala de 10) y permitió clasificar los hogares en dos grupos: 40 tenían un nivel de conocimientos alto y 46, bajo. Los resultados indicaron una asociación entre los conocimientos correctos sobre el SPH en un hogar y el empleo de medidas preventivas contra el SPH en ese hogar.
CONCLUSIONES: Estos resultados tienen implicaciones importantes para emprender acciones dirigidas a mejorar el control y la prevención del SPH.
Palabras clave: Síndrome pulmonar por hantavirus, roedores, etnia y salud, Argentina.
Hantavirus pulmonary syndrome (HPS), a viral disease with a 40-60% mortality rate, is caused by the genus Hantavirus, family Bunyaviridae (1). It has a long-time association with its typical reservoir, the New World rodents of the family Muridae, subfamily Sigmodontinae. The reservoir host is usually asymptomatically infected. Transfer of the virus can occur when either a human enters the host's habitat or the host settles in the proximity of humans (2). People in contact with rodents or their excreta are at risk of hantavirus infection. Certain occupational groups, such as farmers, are at greater risk of infection and also exhibit higher hantavirus antibody prevalence than control groups. Certain activities, such as hand cultivating, woodcutting, reopening of unventilated rooms, and cleaning near infected rodent habitats, have been indicated as high-risk for HPS infection (3, 4).
In Argentina, the first cases of HPS were reported 1995 in the southwestern region. Since then, Argentina has been the South American country with the highest number of officially confirmed cases (5). Current cases are clustered in three geographically-separate areas, i.e., the north (Jujuy Province), the center (Buenos Aires Province-where the study communities are located) and in the southwest (Río Negro Province). The virus responsible for HPS cases in Argentina, the Andes virus, was described in 1995 as a new kind of hantavirus, capable of person-to-person transmission (6, 7).
There are an estimated 100 000 to 200 000 cases of hantavirus infection worldwide per year (8). In Argentina, the total number of HPS cases from 1993- 2004 was 592 (9). Public concern and fears are focused on rodents as the source of HPS. Especially those who work outdoors, such as farmers in hantavirusaffected areas, fear contracting and dying of the disease. Being a country of immigrants, Argentina has many firstgeneration citizens from foreign countries, such as Japan, that are especially concerned with obtaining precise information on HPS prevention, but are dealing with a language barrier (personal communication, Japanese Association, La Plata, 2007).
Although the results of actual condition surveys of medical staff, patients, and their families in relation to HPS have been publicized (10, 11), data focusing on population groups at high-risk for HPS infection are few (12). Researchers in Argentina have made positive efforts to further understanding of the molecular biology and epidemiology of hantaviruses and have discovered new ones, such as the Andes virus (13-18). On the other hand, additional research regarding the inhabitants of epidemiologically high-risk areas and those at risk due to their occupation is required to improve management and prevention strategies. Surveys of community-based knowledge, attitudes, behaviors, and practices (KABP) of a wide range of health issues, such as avian influenza, epilepsy, and HIV/AIDS, have been used successfully to gather information and develop systems and activities (19-21). However, there are no previous studies, as far as the authors know, on HPS knowledge and practices among any high-risk population groups in the world.
The objective of this study was to provide information on the knowledge and practices of HPS among a cluster of the rural Japanese communities in Argentina in which HPS cases have occurred in recent years. Particular emphasis was placed on testing the hypothesis that there must be differences between households relative to the degree of knowledge regarding HPS and the use of recommended preventive measures.
MATERIALS AND METHODS
La Plata is the capital of the Providence of Buenos Aires, located in the central part of Argentina (34º55' S, 57º17' W). The city is about 60 km southeast of the federal capital, the city of Buenos Aires, and is a separate administrative entity (Figure 1). Most of the area is fertile plains at 10 m above sea level. The city has a temperate climate, with a mean annual temperature of 16 ºC and rainfall of 1 000 mm. The mean annual humidity is 78% and a prevailing wind blows from the southeast for four months a year. The total land area is about 940 km2. The population is estimated to be 600 000 (22).
Of the 308 HPS cases registered in Argentina from 1998-2001, about 30% occurred in the Buenos Aires Province (23). Of the 58 HPS cases registered in Buenos Aires Province from 1997 through the first quarter of 2000, more than 50% occurred in La Plata and its neighboring localities. The two lineages of Andes virus (AND Cent Buenos Aires and AND Cent Plata) causing HPS in the province, were found to co-circulate only in La Plata (24). In 2002, Buenos Aires Province recorded more than twice the usual number of HPS cases (52 vs. 20-25); 40 of these occurred in La Plata (25). Colonia Urquiza, home to the Japanese communities that were studied, lies in the suburbs of La Plata. There are 120 Japanese households with approximately 500 Japanese residents, as well as an unknown number of households of various European origins (26). The first 10 Japanese families settled the area in the early 1960s (27). Three major Japanese communities formed in the area based on the time period in which the immigrants arrived (26). Of the study area, 724 hectares are dedicated to agriculture. The location is suitable for floriculture and 60% of the Japanese households engage in this activity.
In Colonia Urquiza, the first HPS cases were confirmed in 1998, including one case (recovered) from the Japanese communities. The first Japanese victim of HPS was confirmed in the communities in 2002. The communities had the second victim of HPS in January 2007, while nine HPS cases (not including Japanese) occurred in Buenos Aires Province in December 2006 (25).
Review articles focusing on HPS were used to design the framework for the questionnaire (1-4, 8, 28). HPS prevention materials designed by public health institutions for use at the household- and community-level were also consulted (29, 30). These were used in conjunction with the biological and epidemiological knowledge currently available to create questions. The questionnaire was designed for anonymous self-completion and organized into three sections: (1) household demographics, (2) HPS knowledge, and (3) HPS preventive measures in use. The questionnaire was written in English and then translated into Spanish and pre-tested, after which a small number of changes were made to improve clarity of questions.
Demographic data collected were as follows: selected characteristics for household head, household members, and the house itself, respectively. Responses to some demographic questions were designed to allow comparison with the results of a field study by other researchers in 2002 (27).
There were 10 questions regarding knowledge of hantavirus transmission and HPS treatment. A summary score was developed from these 10 questions, assigning one point for each correct response and zero for each incorrect or uncertain response. Another 10 basic questions were asked in order to identify HPS preventive techniques common among respondents.
Questionnaires were distributed at the HPS prevention seminar sponsored by the Japanese Association at its meeting hall in Colonia Urquiza on 23 February 2007. Each head-of-household, or if absent, another household adult in attendance, received a questionnaire. In addition, prior to beginning the seminar, an oral presentation in Japanese, designed especially for the newest immigrants, explained the purpose of the questionnaire and asked each head-of-household to complete it. The time allotted to complete the questionnaire was 20 minutes. All the completed questionnaires were then collected by the staff of the association. Any duplicates-from the same household-were eliminated by face-toface assessment. Assistance was given to those who could not read the Spanish language questionnaire.
The data collected from the questionnaires were entered into a database using the OpenOffice.org 2.2 (Sun Microsystems, Santa Clara, California, United States of America). The statistical analyses were performed using the MCA package (31), Stata SE 9.2 (Stata Corporation, College Station, Texas, United States). Maps were produced using the geographical information system software ArcGIS 9.0 (ESRI Incorporated, Redlands, California, United States).
Univariate and multivariate analyses were used to describe the differences between two household groups categorized according to the degree of HPS knowledge. Total HPS knowledge score dichotomized into high (equal to or more than the median knowledge score) and low (less than the median), and univariate analyses were conducted using Fisher's exact test for categorical variables, to identify the variables significantly associated with the HPS preventive measures in use.
Following the univariate analyses, an exploratory multivariate analysis was conducted using multiple correspondence analysis (MCA) to better understand the relationships among a set of categorical variables.
A disadvantage of the univariate analysis was that a set of variables, of which each is weakly associated with the outcome, can become important predictors when they are taken together. To prevent this, a significance level that was relatively safe (P < 0.45) was selected for MCA (32). One of the main objectives of correspondence analysis is to create a visual summary (two-dimensional) of the complicated associations that exist among a set of categorical variables (both predictors and the outcome). The two axes are factorial axes that indicate the most inertia (variability) in the original predictor variables. The result is a scatter-plot that determines clusters of closely-related predictors, with clusters farther from the intersection of the axes having stronger associations. The values of the outcome variable (also categorical) can also be projected on the same axes to identify which clusters of predictor variable values are associated with the outcomes of interest (33).
The 86 households that completed the questionnaire accounted for about 72% of the total Japanese households in the study area. The survey achieved 100% participation among the households attending the seminar, according to the staff of Japanese Association in La Plata, which was charged with collecting the completed questionnaires.
The demographic characteristics of the study households are shown in Table 1. The median number of household members and children was in broad agreement with the results of the field study mentioned above (three or four members, including one or two children in many families). Twelve percent of them responded that at least one family member had been diagnosed, clinically or serologically, with HPS during the preceding decade.
The percentage of the respondents' answers that reflected accurate HPS knowledge varied greatly between questions (Table 2). The percentage of questions that were answered correctly regarding the hantavirus-affected area, population at high risk, mortality, disinfection, and path of infection was relatively low (< 30%). The median knowledge score of 5 (range: 0-9, of 10) divided the study households into two groups: highknowledge score group (n = 40) and lowknowledge score group (n = 46). Table 3 represents the relationship between selected HPS preventive measures and the knowledge score categories. The percentages for each preventive measure variable of the low-score group (range: 17-93) were more variable than those of the high-score group (range: 45-95). The low-score group had lower percentages for each preventive measure variable, except for one regarding the cleanliness of outdoor garbage cans (no statistical significance) compared to those of the high-score group.
Of the 10 preventive measures shown in Table 3, six variables were selected for MCA (Figure 2). The two dimensions presented in the plot explain 55% of inertia. The first dimension distinguishes between use of various preventive measures, whereas the second separates according to the knowledge score category. Except for the preventive measure indicators "cleaning up the outdoor grill/barbeque" and "use of soap when washing hands," all the plots, including outcome variable points (knowledge score category), were clustered into two areas. On visual assessment in Figure 2, the cluster of the five variables coded 1 are more closely associated than the cluster of those coded 0.
This survey represents a first attempt to understand perceptions regarding HPS knowledge and practices among a cluster of the rural Japanese communities in an epidemiologically high-risk area in Argentina. The fact that more than 70% of the study households attended the HPS prevention seminar reflects high public interest in the disease. The seminar sessions organized both in Japanese and Spanish were well received by the first and younger generation settlers. More than half of the respondents had obtained hantavirus knowledge through face-to-face communication, although the information may not always have been accurately interpreted. This might be explained by the fact about two-thirds of the study households used Japanese at home as the primary language, while HPS information was being disseminated in Spanish by the mass media. Educational materials, especially for the first generation settlers, were needed. Consequently, an informative leaflet on HPS prevention was produced in Japanese in order to improve the HPS knowledge of inhabitants (Japanese Association in La Plata, 2007, unpublished).
It is clear that for community-based disease prevention programs to be successful in the short-term and sustainable in the long-term, inhabitants have to receive a perceived benefit from the program, one that does not necessarily have to be measurable on purely economic grounds (8, 12). Therefore, it is important to create a trusting relationship between the general public and officials. In the seminar sessions, municipal officials in charge of HPS management and prevention gave a lecture and emphasized strengthening collaboration with the Japanese communities.
The findings in Figure 2 in conjunction with Table 3 suggest an association between the knowledge background of individual households and their respective attitudes and the measures they take to prevent HPS. As the authors hypothesized, knowledge influences practices. The current study indicates a significant association between those who practice these preventive measures: (1) store animal feed properly, (2) use rubber gloves when cleaning, and (3) use rat traps, and the accurate knowledge that these are standard hygienic practices that reduce the risk of contracting hantavirus. In addition, it is notable that the main source of information was the person-to-person communication (54%) and not the media or governmental publicity. These findings support the importance of media campaigns to implement educational and policy strategies.
Preventing exposure to rodents and their excreta lessens the risk of infection. Efforts should include the removal of rodent food sources from inside the home, measures to inhibit rodents access to the home, and elimination of possible nesting sites and food sources from the area surrounding the home. When cleaning up areas that are possibly rodent-infested, proper safeguards should be taken (aeration of the room before entering, use of rubber gloves and disinfectant, avoidance of stirring up and inhaling dust). Rodents should be managed by traps; use of gloves and masks is recommended during manipulation of traps and carcasses (8). For a more general prevention of human infections, especially in risk groups such as the Japanese communities in the study area, the development of a hantavirus vaccine is necessary (1).
Climatic and other environmental factors may govern the population size and migration pattern of relevant hosts. It is essential to pay attention to the consequences of land use changes, especially those that increase human contact with potential reservoirs, such as rodents living in wetlands. In recent years, for example, there was an increase in the number of sites near La Plata that were being used for soil extraction to support brick fabrication. These sites were then abandoned and converted into artificial wetlands with typical flora and fauna (34). The study communities have also expressed concerns over the municipal government's plans to build a city dump near the communities. A dump would likely become another breeding ground for rodents.
Another challenge lies in the fact that the reservoir of the two HPS-causing lineages of Andes virus in La Plata have not yet been identified (24). Detailed knowledge of rodent species distribution and their role as hantavirus reservoirs is needed.
When the potential respondents who were absent from the seminar were taken into account, it was apparent that the sample was not totally representative of the communities in general. The responses obtained are likely to represent inhabitants who are more motivated and interested in the topic. In addition, the questionnaire did not include questions regarding the educational level of respondents or their knowledge of warning signs and symptoms. This angle needs additional research. A lack of detailed demographics and HPS case statistics for the area, which is not a single administrative area, but rather straddles the border between districts, hampers the comparison of HPS cases among different ethnic groups (e.g., between those of Japanese descent vs. those of European descent).
Rodent control in and around the home remains the primary strategy for preventing hantavirus infection. From the public health point of view, the recommended measures that need to be used in concert are: (1) prevent rodents from entering the home by repairing gaps inside and outside the house, (2) trap rodents around the home to help reduce the population, (3) clean up rodent food sources and nesting sites, and (4) take precautions when cleaning rodent-infested areas. It is important to consider that dissemination and widespread adoption of preventive measures require education. Designing and implementing HPS educational programs and measuring their effectiveness should be priorities to incent the communities to take a more active role.
Acknowledgements. The study was carried out as part of the project for the capacity development for improvement of livestock hygiene in southern part of South America through regional cooperation (Proyecto de Desarrollo Profesional Continuo para los Veterinarios del Sur- PROVETSUR), funded by the Japan International Cooperation Agency. We wish to thank the staff of the Japanese Association (Asociación Japonesa La Plata) for their support. We are extremely grateful to the respondents who allowed us to work with them. Valuable and insightful comments by the reviewers and editor are gratefully acknowledged. We declare that we have no competing interests.
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Manuscript received on 28 October 2007.
Revised version accepted for publication on 14 July 2008.