Abstract. Between November 1993 and March 1994, a cluster 6 pediatric patients with acute febrile illnesses associated with rashes was identified in Jujuy Province, Argentina. Immunohistochemical staining of tissues confirmed spotted fever group rickettsial infection in a patient with fatal disease, and testing of serum of a patient convalescing from the illness by using an indirect immunofluorescence assay (IFA) demonstrated antibodies reactive with spotted fever group rickettsiae. A serosurvey was conducted among 16 households in proximity to the index case. Of 105 healthy subjects evaluated by IFA, 19 (18%) Between November 1993 and March 1994, 6 children presented to medical practitioners in Jujuy Province in northwestern Argentina with illnesses characterized by fever, headache, purpuric rash, and a history of tick bite 1-2 weeks preceding the illness. This cluster included two fatal cases occurring in a family residing in Saladillo in the Santa Barbara Department of Jujuy Province (Figure 1). The clinical and epidemiologic findings common to each case suggested a rickettsial etiology. In this report, we describe evidence for spotted fever group rickettsial infections in northern Argentina, including laboratory-confirmed infections in patients with acute disease, and serologic evidence of past rickettsial and ehrlichial infections among healthy persons residing in Jujuy Province. METHODSDescription of the area. Jujuy Province is situated in northwestern Argentina (Figure 1) and is a relatively warm (20-22ЊC) subtropical region located at 2,200 feet (670 meters) elevation. The average annual rainfall is 32 in (80 cm), and most precipitation occurs between December and March. The province has a stable population of approximately 560,000 inhabitants. The study area of Palma Sola and surroundings (which includes the town of Saladillo) has a population of approximately 2,000 persons. It is located in the Department of Santa Barbara, with a population of 15,540 persons. The terrain consists of partially forested rolling hills that support a diverse collection of birds, small, medium, and large mammals, as well as many domesticated animals including dogs, cattle, pigs, and horses. Adult A. cajennense have been collected from dogs and horses in the region.Serosurvey. Healthy persons from 16 households in Saladillo were interviewed and a peripheral blood specimen was collected from each person. The interview included questions on prior tick bites and on illnesses at any time, specifically illnesses with signs and symptoms compatible with rickettsial spotted fever. Informed consent was obtained for the survey following guidelines of the U.S. Department of Health and Human Services and those of the Jujuy Provincial Ministry of Social Welfare for clinical studies.Immunohistochemistry. Sections of formalin-fixed, paraffin-embedded tissues obtained at autopsy from a patient with fatal disease were evaluated for spotted fever group rickettsial infection using an indirect immunoalkaline phosphatase staining technique. 9 ...

Five species of sigmodontine rodents have been identified in Argentina as the putative reservoirs of six circulating hantavirus genotypes. Two species of Oligoryzomys are associated with the genotypes causing hantavirus pulmonary syndrome, Oligoryzomys flavescens for Lechiguanas and O. longicaudatus for Andes and Oran genotypes. Reports of human cases of hantavirus pulmonary syndrome prompted rodent trapping (2,299 rodents of 32 species during 27,780 trap nights) at potential exposure sites in three disease-endemic areas. Antibody reactive to Sin Nombre virus was found in six species, including the known hantavirus reservoir species. Risk for peridomestic exposure to host species that carry recognized human pathogens was high in all three major disease-endemic areas.

The purpose of this study was to characterize the hantaviruses circulating in northwestern Argentina. Human and rodent studies were conducted in Yuto, where most cases of hantavirus pulmonary syndrome (HPS) occur. Partial virus genome sequences were obtained from the blood of 12 cases of HPS, and from the lungs of 4 Calomys callosus and 1 Akodon simulator. Phylogenetic analysis showed that three genotypes associated with HPS circulate in Yuto. Laguna Negra (LN) virus, associated with C. laucha in Paraguay, was identified for the first time in Argentina; it was recovered from human cases and from C. callosus samples. The high sequence identity between human and rodent samples implicated C. callosus as the primary rodent reservoir for LN virus in Yuto. The genetic analysis showed that the Argentinian LN virus variant differed 16.8% at the nucleotide level and 2.9% at the protein level relative to the Paraguayan LN virus. The other two hantavirus lineages identified were the previously known Bermejo and Oran viruses.

We initiated a study to elucidate the ecology and epidemiology of hantavirus infections in northern Argentina. The northwestern hantavirus pulmonary syndrome (HPS)–endemic area of Argentina comprises Salta and Jujuy Provinces. Between 1997 and 2000, 30 HPS cases were diagnosed in Jujuy Province (population 512,329). Most patients had a mild clinical course, and the death rate (13.3%) was low. We performed a serologic and epidemiologic survey in residents of the area, in conjunction with a serologic study in rodents. The prevalence of hantavirus antibodies in the general human population was 6.5%, one of the highest reported in the literature. No evidence of interhuman transmission was found, and the high prevalence of hantavirus antibody seemed to be associated with the high infestation of rodents detected in domestic and peridomestic habitats.

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