Hirayama disease: three cases.

Hirayama disease is a rare, lower cervical myelopathy affecting young adults. It is responsible for pure distal motor impairment of the upper limbs, with slow progressive development in the metameric territories of C7 to T1. It is thought to be caused by movements involved in flexing the neck. Neutral position magnetic resonance imaging (MRI) looks for abnormal cervical curvature, atrophy with flattening of the cervical spine, anterior cord hyperintensity and especially a lack of posterior apposition of the dural sac. If the condition is suspected, an MRI in flexion should be performed to show anterior displacement of the cord and dural sac, enlargement of the posterior epidural space, an increase in flattening of the cord and congestion of the epidural veins. These dynamic abnormalities tend to disappear after evolving for 10 years. We report two confirmed cases and a probable case of Hirayama disease and discuss its physiopathology.

Control of cystic echinococcosis/hydatidosis: 1863-2002.

Echinococcosis/hydatidosis, caused by Echinococcus granulosus, is a chronic and debilitating zoonotic larval cestode infection in humans, which is principally transmitted between dogs and domestic livestock, particularly sheep. Human hydatid disease occurs in almost all pastoral communities and rangeland areas of the underdeveloped and developed world. Control programmes against hydatidosis have been implemented in several endemic countries, states, provinces, districts or regions to reduce or eliminate cystic echinococcosis (CE) as a public health problem. This review assesses the impact of 13 of the hydatid control programmes implemented, since the first was introduced in Iceland in 1863. Five island-based control programmes (Iceland, New Zealand, Tasmania, Falklands and Cyprus) resulted, over various intervention periods (from <15 to >50 years), in successful control of transmission as evidenced by major reduction in incidence rates of human CE, and prevalence levels in sheep and dogs. By 2002, two countries, Iceland and New Zealand, and one island-state, Tasmania, had already declared that hydatid disease had been eliminated from their territories. Other hydatid programmes implemented in South America (Argentina, Chile, Uruguay), in Europe (mid-Wales, Sardinia) and in East Africa (northwest Kenya), showed varying degrees of success, but some were considered as having failed. Reasons for the eventual success of certain hydatid control programmes and the problems encountered in others are analysed and discussed, and recommendations for likely optimal approaches considered. The application of new control tools, including use of a hydatid vaccine, are also considered.

Porcine and rodent infection with Trichinella, in the Sierra Grande area of Rio Negro province, Argentina.

In 2000, two cases of human trichinellosis were detected in the Sierra Grande area of Rio Negro province, Argentina. As part of an investigation of the aetiology of these cases, 300 pigs slaughtered for consumption in the area between 2000 and 2002 were checked for Trichinella infection, by artificial digestion of a muscle sample. Twelve (5.6%) - four (7.3%) of the 55 checked in 2000, five (4.8%) of the 105 investigated in 2001, and three (2.1%) of the 140 investigated in 2002 - were found infected. Blood samples were collected from other pigs aged > 6 months old, so that sera could be tested, in ELISA and by western blotting, for anti- Trichinella antibodies. Of the 181 animals checked in the initial serological survey, 36 (19.9%) were found seropositive for Trichinella. When 35 of the seronegative pigs were re-checked 6 months later, three (8.6%) were found to have seroconverted. Four (15.4%) of 26 local rodents, caught in Sherman-type traps, were also found positive when checked for infection by artificial digestion. It appears that about 20% of pigs in the study area are infected each year, this high level of transmission being sustained by a high prevalence of infection in the local rodent populations.

Vigilancia epidemiológica de enfermedades transmitidas por alimentos en la Provincia de Río Negro, Argentina, 1993-2001 / Surveillance of foodborne diseases in the province of Rio Negro, Argentina, 1993-2001

A total of 39 outbreaks of foodborne diseases affecting 958 people in the province of Rio Negro, Argentina between 1993 and 2001 are described and evaluated. The main causal agents were identified involving food, sites of occurrence, risk factors and notification system used. Salmonella spp (38%), Trichinella spiralis (15%), Escherichia coli (13%) and Staphylococcus aureus (15%) were the most frequent agents present in outbreaks. Salmonella spp produced the largest number of cases (52%). Food involved were cooked meat (36%), cheese (10%), sandwiches (10%), deserts (10%) and ice cream (8%). Indeed, ice creams were involved in the largest number of cases and of people affected. In relation to the source of food, 41% of outbreaks were caused by homemade meals, 23% by catering or ice cream parlor, 13% in family parties, 8% in county fairs and 8% in hotel restaurants. In 28% of the outbreaks the etiological agent was identified exclusively by epidemiological analysis, in 64% isolation of the agent was carried out, and in 8% of the cases, a final diagnosis could not be obtained. Validity of epidemiological studies in foodborne disease, the necessity of strengthening the notification system of outbreaks, and the importance of good practices in food handling are analyzed.(AU)

Se describen 39 brotes de enfermedades transmitidas por alimentos que afectaron a 958 personasen la provincia de Río Negro, Argentina, en el período 1993- 2001. Se identifican los agentes causales, los alimentos involucrados, los sitios de ocurrencia, los factores de riesgo involucrados y los mecanismosde notificación empleados. Salmonella spp (38%), Trichinella spiralis (15%), Escherichia coli (13%) y Staphylococcus aureus (15%) resultaron los agentes más frecuentes en los brotes. Salmonella spp. tambiénprodujo el mayor número de casos (52%). Los principales alimentos involucrados resultaron cárneos (36%),quesos (10%), fiambres y sándwiches (10%), postres (10%) y helados (8%). El mayor número de casos, por suparte, fue causado por la ingestión de helados (37%). Con relación al origen de los alimentos, 41% de los brotesfueron causados por comidas elaboradas en los domicilios, 23% en establecimientos comerciales, 13% enfiestas familiares, 8% en fiestas comunitarias y 8% en restaurantes de hoteles. En el 28% de los brotes fueidentificado el agente etiológico por análisis epidemiológico exclusivamente, en el 64% se logró el aislamientodel agente, mientras que en el 8% de los casos no se logró el diagnóstico definitivo. Se analiza el valor de laencuesta epidemiológica en los estudios de enfermedades transmitidas por alimentos, la necesidad de fortalecerel sistema de notificación médica de casos y brotes y la importancia de las buenas prácticas en la manipulaciónde alimentos.(AU)

Vigilancia epidemiológica de enfermedades transmitidas por alimentos en la Provincia de Río Negro, Argentina, 1993-2001 / Surveillance of foodborne diseases in the province of Rio Negro, Argentina, 1993-2001

A total of 39 outbreaks of foodborne diseases affecting 958 people in the province of Rio Negro, Argentina between 1993 and 2001 are described and evaluated. The main causal agents were identified involving food, sites of occurrence, risk factors and notification system used. Salmonella spp (38%), Trichinella spiralis (15%), Escherichia coli (13%) and Staphylococcus aureus (15%) were the most frequent agents present in outbreaks. Salmonella spp produced the largest number of cases (52%). Food involved were cooked meat (36%), cheese (10%), sandwiches (10%), deserts (10%) and ice cream (8%). Indeed, ice creams were involved in the largest number of cases and of people affected. In relation to the source of food, 41% of outbreaks were caused by homemade meals, 23% by catering or ice cream parlor, 13% in family parties, 8% in county fairs and 8% in hotel restaurants. In 28% of the outbreaks the etiological agent was identified exclusively by epidemiological analysis, in 64% isolation of the agent was carried out, and in 8% of the cases, a final diagnosis could not be obtained. Validity of epidemiological studies in foodborne disease, the necessity of strengthening the notification system of outbreaks, and the importance of good practices in food handling are analyzed.

Se describen 39 brotes de enfermedades transmitidas por alimentos que afectaron a 958 personasen la provincia de Río Negro, Argentina, en el período 1993- 2001. Se identifican los agentes causales, los alimentos involucrados, los sitios de ocurrencia, los factores de riesgo involucrados y los mecanismosde notificación empleados. Salmonella spp (38%), Trichinella spiralis (15%), Escherichia coli (13%) y Staphylococcus aureus (15%) resultaron los agentes más frecuentes en los brotes. Salmonella spp. tambiénprodujo el mayor número de casos (52%). Los principales alimentos involucrados resultaron cárneos (36%),quesos (10%), fiambres y sándwiches (10%), postres (10%) y helados (8%). El mayor número de casos, por suparte, fue causado por la ingestión de helados (37%). Con relación al origen de los alimentos, 41% de los brotesfueron causados por comidas elaboradas en los domicilios, 23% en establecimientos comerciales, 13% enfiestas familiares, 8% en fiestas comunitarias y 8% en restaurantes de hoteles. En el 28% de los brotes fueidentificado el agente etiológico por análisis epidemiológico exclusivamente, en el 64% se logró el aislamientodel agente, mientras que en el 8% de los casos no se logró el diagnóstico definitivo. Se analiza el valor de laencuesta epidemiológica en los estudios de enfermedades transmitidas por alimentos, la necesidad de fortalecerel sistema de notificación médica de casos y brotes y la importancia de las buenas prácticas en la manipulaciónde alimentos.

A case-control study of the risk factors for cystic echinococcosis among the children of Rio Negro province, Argentina.

In 1984 the prevalence of cystic echinococcosis (CE) in Rio Negro province in central Argentina reached alarming levels, with almost 6% of children aged 7-13 years infected with the causative agent, Echinococcus granulosus. Although the control activities developed between 1980-2000 have now lowered the prevalence of infection in this age-group to 1.1%, transmission of E. granulosus has clearly not ceased. The aim of the present study was to identify possible flaws in the control programme and the risk factors associated with CE. The 24 cases and 66 controls used were identified during a survey of the 1,070 schoolchildren attending 12 schools in Ingeniero Jacobacci, Rio Negro province. In interviews based around a standardized questionnaire, the adult female with responsibility for each subject (usually the mother but sometimes a grandmother or guardian) was asked 70 questions about the child and his or her immediate family, their contact with dogs and relevant environmentmental factors, and their level of contact with the control programme. Univariate and multivariate analyses were used to determine odds ratios (OR) and their 95% confidence intervals (CI). The main risk factors found to be significantly associated with CE were having a family member with the disease (OR = 3.11; CI = 0.92-10.47), spending the first years of life surrounded by a large number of dogs (OR = 2.11; CI = 1.2-3.5), and having a father who slaughtered sheep at his workplace (OR = 1.14; CI = 1.04-1.24). Obtaining drinking water from a tap (OR = 0.28; CI = 0.08-1.01) also remained in the final model, as a protective factor.

Seasonal variation in prevalence of antibody to hantaviruses in rodents from southern Argentina.

We conducted a small mammal trapping study to investigate temporal variation in prevalence of infection in hantavirus reservoir populations in the Patagonian Andes mountain range, Rio Negro province, Argentina. Rodent blood samples collected in natural and periurban habitats and at the home of an hantavirus pulmonary syndrome (HPS) case patient were analysed by enzyme-linked immunosorbent assay. Organ tissue samples were tested by polymerase chain reaction (PCR) and nucleotide sequence analysis. Eight species of 1032 rodents were captured in 15 551 trap nights, giving an overall trap success of 6.6%. Hantavirus antibody was detected in 30 of 555 Oligoryzomys longicaudatus (reservoir of Andes virus), three of 411 Abrothrix longipilis, and one of 10 Loxodontomys micropus. Antibody prevalences in O. longicaudatus were 13.7% in spring 1996, 59.3% in summer 1996, 2.1% in autumn 1997, 12.4% in winter 1997 and 3.1% in spring 1997. A much higher antibody prevalence (33%) was found during trapping around the residence of an HPS case patient. Higher prevalences were found in older male O. longicaudatus. There was no apparent correlation of antibody prevalence with rodent population density, or of rodent population density or antibody prevalence with numbers of human cases. For an HPS case that occurred in our study area in 1997, we identified the probable rodent reservoir and likely site of exposure by matching the genetic sequences of virus obtained from a rodent and the HPS case patient.

Ovine Echinococcus granulosus transmission dynamics in the province of Rio Negro, Argentina, 1980-1999.

In this work, the impact of a hydatidosis control programme for dogs on the intermediate ovine host was specifically analysed to determine the levels of prevalence achieved and the dynamics of parasite transmission, as well as to evaluate the quality of diagnostic systems in slaughterhouses. A field study was conducted in four slaughterhouses (Valcheta, Los Menucos, Jacobacci, Bariloche) that process animals coming from all the departments within the work area. The control programme for dogs entailed treating dogs with 5 mg/kg praziquantel at 2-month intervals for 20 years. Sample size was determined with a 10% error margin and a 95% significance level. Harvested viscera (liver, lungs, kidneys) were preserved in 5% formaldehyde and sent to the laboratory for diagnostic confirmation of both positive and negative specimens. The 61% initial prevalence dropped to 18.3% at the end of the 10-year period, observed differences proving significant (Chi-square=15.454, P=0.00). There were statistically significant increases in infection prevalence with age (Pearson's Chi-square=133.61, P=0.00). Overall, 37.2% of hydatidosis cases diagnosed in slaughterhouses were considered non-hydatid by histological study. On the other hand, 1.1% of those diagnosed as healthy were found to be infected with hydatidosis. The number of hydatid cysts per animal increased with age: 0.04 in lambs and 1.22 in adults (linear regression equation, -0.0539+0.0127 x age), whereas the average for the whole period was 3.7% in lambs and 20.5% in adults. Viability studies indicated that 63.8% of parasitised animals had viable cysts, out of which 53.3% were fertile. Diagnosis of infection in sheep made by means of an adjusted statistical design and with histological confirmation of the presumptive diagnosis made in slaughterhouses demonstrated the flaws of the official systems for epidemic surveillance of hydatidosis. However, there was no overall significant difference in slaughterhouse and laboratory data.Ro was 0.53 and could imply a decrease in reproductive capacity of the parasite and steady state extinction.

Epidemiological surveillance of human hydatidosis by means of ultrasonography: its contribution to the evaluation of control programs.

Epidemiological surveillance for hydatidosis is based on initial determination and follow-up of the infestation rate in man, sheep and dogs. The use of ultrasonography (US) as a screening method has demonstrated its usefulness in detecting asymptomatic human carriers of abdominal hydatidosis. To evaluate the contribution of US to epidemiological surveillance within the framework of disease control programs, we performed 719 US studies in school children from 7 to 13 years of age, in rural areas of Río Negro, Argentina, subjected to canine deparasitization during 1984/1986 and 1997/1998. In the first period, 15/268 (5.6%), while in the second, 5/451 (1.1%) carriers were detected (P < 0.0004). The average diameter of the cysts was 4.71 cm in 1984/1986 and 2.14 in 1997/1998. US as a mass screening method allows evaluation of early changes in human prevalence rates, closely related to infestation rates in sheeps and dogs, thus providing a sensitive indicator of the evaluation of control programs.

Human cystic echinococcosis: contributions to the natural history of the disease.

In areas where human cystic echinococcosis (CE) is endemic, the results of ultrasonographic or X-ray examinations have revealed a surprisingly high prevalence of abdominal cysts in asymptomatic individuals. The results of preliminary studies indicate that the ratio of liver infection:lung infection (LI:LU) is much higher in the asymptomatic individuals (9:1 or 7:1) than is usual among symptomatic cases of liver CE (2:1). This difference may indicate that, compared with lung cysts, liver cysts rarely cause morbidity, perhaps because they grow at a slower rate than those in the lungs. In an attempt to explore this possibility, the published results of ultrasonographic and radiological surveys on general populations and the records of autopsies and hospital-based investigations of symptomatic cases of liver CE were reviewed. In general populations, the overall prevalence of cysts in the liver (2.5%) was found to be much higher than that of cysts in the lungs (0.3%), giving a LI:LU ratio of 8.3:1. In the symptomatic cases, however, LI:LU ratios were only 2.5:1 (based on hospital records) or 4.1:1 (based on autopsy records). In addition, the estimated mean growth rate of the cysts in 53 surgical cases of CE from the province of Río Negro in Argentina was found to be significantly higher than that of the cysts in 89 asymptomatic cases detected during ultrasonographic surveys in the same area.

Rate of infection and of reinfection by Echinococcus granulosus in rural dogs of the province of Rio Negro, Argentina.

Hydatidosis (cystic echinococcosis) constitutes a serious public health problem in the Province of Rio Negro, Argentina. In the present work it was intended to evaluate the prevalence of the canine echinococcosis in rural areas of the Province of Rio Negro and studied the reinfection rate in dogs after treatment with Praziquantel during the period 1980-1997. A total of 496 dogs were studied in 18 canine concentrations in order to establish the initial prevalence rate which was 42.3%. From 1980 onward dogs should have been systematically treated with anthelmintic every 2 months in rural areas and every 6 months in urban areas. We estimated that approximately 65% of dogs were treated. To determine the reinfection rate, 476 dogs (1984) and 598 dogs (1996) were studied after anthelmintic treatment during two sequential time periods (0-45; 46-90 days). In both cases treated animals were compared with untreated dogs. Prevalences were 3.5%, 6.7% and 21.3% in 1984 and 0.8%, 4.0% and 10.0% in 1996. For the purpose of surveillance a total number of 21,444 dogs were studied during 18 years. Prevalence of Echinococcus granulosus decreased significantly in the first year from 42.3% to 6.1%.

[Asymptomatic carriers of hydatidosis: epidemiology, diagnosis, and treatment]. / Portadores asintomáticos de hidatidosis: epidemiología, diagnóstico y tratamiento.

Until a short time ago, hydatidosis was considered a pathology that could only be resolved surgically. However, in recent years progress has been made with the epidemiology, diagnosis, and treatment of the disease, and new information on the natural history of hydatidosis has helped define new criteria for its treatment. It is now known that as many as 67% of the carriers of liver cysts who are asymptomatic remain so throughout their lives. This situation produces special results in immunologic testing. Enzyme-linked immunosorbent assay (ELISA) has a sensitivity of 63% and a specificity of 97% with asymptomatic carriers, while the double diffusion arc 5 test (DD5) achieves a sensitivity of only 31% with the same population. On the other hand, imaging studies based on ultrasonography have become the method of choice to detect asymptomatic carriers. Ultrasonography studies are 49% to 73% more sensitive than serological tests, and they can even be used as a part of epidemiological surveillance systems and to monitor control programs. Treatment schemes have also been modernized. Treating asymptomatic carriers chemotherapeutically with albendazole produces favorable results in as many as 69% of cases, while such minimally invasive surgical treatments as puncture-aspiration-injection-reaspiration (PAIR) reduce average cyst volume by as much as 66%. These factors have made it possible for hospital services in the province of Río Negro, Argentina, to establish a treatment scheme for asymptomatic carriers. It is based on the monitoring of small cysts (type Ia on the modified Gharbi scale); initial treatment with albendazole, followed by PAIR if there is no response, in larger or more complex cysts (types Ib, II, and III); and follow-up of inviable or dead cysts (types IV and V).

Diagnosis of human hydatidosis. Predictive value of a rural ultrasonographic survey in an apparently healthy population.

The usefulness of ultrasonography (US) in the early diagnosis of hydatidosis, applied in large-scale surveys to populations lacking clinical symptoms of the disease, has been amply documented. However, the rate of false positive and negative results is poorly described. Due to this, the present paper is aimed to evaluate the sensitivity, specificity and predictive value of a conventional rural ultrasonographic survey in comparison with higher imaging complexity. Accordingly, during 1997 and 1998 a total of 1054 children from 7 to 14 years of age were evaluated by means of US, in the town of Ingeniero Jacobacci, Province of Rio Negro, Argentina, employing a portable device for population studies. All detected cases were referred to a high complexity center specialized in imaging diagnosis for their re-evaluation with US, CT scanning and X-rays. A control group comprising 3 children negative by US for each positive case in the mass screening survey was selected and reexamined by US and X-rays and CT scanning in doubtful situations. Twenty-seven asymptomatic carriers were referred with images compatible with hydatid cysts, while 66 were classified as disease free. At reexamination, 24 of those diagnosed as carriers and the totality of those classified as healthy were confirmed. On the basis of our results, a sensitivity of 100%, a specificity of 95.6% and a global test value of 96.7% were estimated.

Diagnosis of human hydatidosis. Predictive value of a rural ultrasonographic survey in an apparently healthy population.

The usefulness of ultrasonography (US) in the early diagnosis of hydatidosis, applied in large-scale surveys to populations lacking clinical symptoms of the disease, has been amply documented. However, the rate of false positive and negative results is poorly described. Due to this, the present paper is aimed to evaluate the sensitivity, specificity and predictive value of a conventional rural ultrasonographic survey in comparison with higher imaging complexity. Accordingly, during 1997 and 1998 a total of 1054 children from 7 to 14 years of age were evaluated by means of US, in the town of Ingeniero Jacobacci, Province of Rio Negro, Argentina, employing a portable device for population studies. All detected cases were referred to a high complexity center specialized in imaging diagnosis for their re-evaluation with US, CT scanning and X-rays. A control group comprising 3 children negative by US for each positive case in the mass screening survey was selected and reexamined by US and X-rays and CT scanning in doubtful situations. Twenty-seven asymptomatic carriers were referred with images compatible with hydatid cysts, while 66 were classified as disease free. At reexamination, 24 of those diagnosed as carriers and the totality of those classified as healthy were confirmed. On the basis of our results, a sensitivity of 100

, a specificity of 95.6

and a global test value of 96.7

were estimated.

Long-term outcome of asymptomatic liver hydatidosis.

BACKGROUND/AIMS: The aim of this study was to determine the outcome of asymptomatic liver hydatid cysts in a cohort of 33 out of 59 carriers by evaluating clinical and ultrasonographic (US) changes 10-12 years after initial diagnosis. METHODS: We compared US features and cyst size with the original descriptions from 1984-1986. Patients were questioned about hydatid-related symptoms and signs. RESULTS: Thirty-three of the 59 carriers could be reevaluated, five (15.2%) of whom had undergone surgery without presenting symptoms, while of 28 unoperated cases, 21 (75%) remained asymptomatic. Of the unoperated cases evaluated by US, in 8/14 (57.1%) there were no modifications in cyst size during the 10-12-year period, in five (35.7%) growth was slight (<3 cm) and in one (7.1%) the cyst grew 4 cm. Mean cyst growth in all 14 cases was 0.7 cm. CONCLUSIONS: Despite the limited number of cases, our results show that most asymptomatic liver hydatid cases (75%) remain symptom-free for more than 10 years, regardless of cyst size or type. We believe that such carriers are at low risk of developing complications, so that it is difficult to establish specific rules for their therapy, if any. Longitudinal follow-up of larger series of asymptomatic hepatic hydatidosis cases is essential to gain a deeper insight into the natural history of such patients, and to draw up comprehensive guidelines for treatment.

[Treatment of hepatic hydatid cysts by percutaneous aspiration and hypertonic saline injection: results of a cooperative work]. / Tratamiento de quistes hidatídicos hepáticos por aspiración percutánea e inyección de solución salina hipertónica: resultados de un trabajo cooperativo.

Percutaneous puncture-aspiration-injection-reaspiration (PAIR) of hydatid liver cysts, was performed in 38 patients 14-80 years old, with a total of 60 liver hydatid cysts. After aspiration under computed tomography guidance, hypertonic saline was injected into the cystic cavities of patients as a scolecidal agent. No major complications were associated with the procedures. In the follow-up period of 18 months, control CT scans of 35 cysts revealed a gradual decrease in cyst size with a mean volume reduction of 66%. Complications included two cases of urticaria, one case of anaphylaxis and one subcapsular hematoma. No mortality occurred. It is concluded that percutaneous aspiration and hypertonic saline injection for liver hydatid cysts appears to be an effective form of treatment and may eventually prove to be an alternative to surgical intervention.

Hydatidosis in the province of La Pampa, Argentina, 1998.

Echinococcus granulosus is the agent that causes the classical hydatidosis or cystic echinococcosis. The most spread cycle in South America is the sheep-dog cycle, and offers favorable conditions for the development of the parasite. As the province of La Pampa shows an endemic presence with notification of cases and infected dogs, the present work has the aim of contributing to the study of the distribution and prevalence of the disease in the district of Maracó, La Pampa, Argentina. Dogs of 36 farms that had ovines, were dosed with arecoline hydrobromide at a dose of 3.5 mg/kg. Dogs from 27 (75%) farms resulted positive to Tenia sp. and 3 (8.3%) to E. granulosus. Blood samples were taken to all the people living in all the inquired farm and were processed by the ELISA test for hydatidosis. A retrospective survey on cases of human hydatidosis attended in the Hospital of General Pico, head if the sanitary region, and in two private clinics was performed. Analysis of clinical records indicated 11 cases operated during the period 1996/1997 (annual incidence rate of 6.8 per 100,000 inhabitants). It is of public health interest to fulfill epidemiologic investigations in other districts of the Province of La Pampa with the aim of delimitating the endemic distribution within the province and also organizing surveillance systems on human hydatidosis.

Hantavirus pulmonary syndrome in the Province of Rio Negro, Argentina, 1993-1996.

Early in 1995 the first case of Hantavirus Pulmonary Syndrome was serologically confirmed in El Bolsón (Province of Río Negro, Argentina), corresponding to the third outbreak reported in Argentina. A total of 26 cases of HPS related to the Andean region of Rio Negro Province, were reported from 1993 to 1996, 17 in El Bolsón, 4 in San Carlos de Bariloche, and 5 in Buenos Aires. The incidence rate was 5.03 x 100,000 with a mortality rate of 51.85 x 100. The occurrence of cases was mainly seasonal, with a significantly greater number in the spring, and the persons affected mainly lived in urban or periurban areas. In four cases, the affected individuals were members of a couple, spouses or live-in contacts. Seven cases were Health workers (physicians, nurses or administrative staff). Twelve cases were related among them, due to an outbreak of 80 days. Two of them did not visit the Andean region. A total of 139 rodents were captured and seven of them, Olygoryzomys longicaudatus, were found to be serologically positive. The possibility of infection by contact with rodents or fecal matter is being analyzed and also hypothesis related with interhuman transmission.