Hantavirus pulmonary syndrome (HPS), a severe respiratory disease with high mortality caused by rodent-borne hantaviruses, has previously been identified in the United States and Canada as well as central and southern South America. In late 1999 and early 2000, an outbreak of acute illness compatible with HPS was reported in Los Santos, Panama, with the death of 3 of the 12 (25%) suspected cases. Hantavirus-specific antibodies were detected in patient sera, and virus RNA was detected by reverse transcriptase-polymerase chain reaction. Sequence analysis of virus genome N-, G1-, and G2-encoding fragments showed this to be a novel hantavirus, Choclo virus. Serologic and virus genetic analyses of rodents trapped in the area showed Oligoryzomys fulvescens to be the likely reservoir for the HPS-associated Choclo virus. In addition, Zygodontomys brevicauda rodents were shown to harbor another genetically unique hantavirus, Calabazo virus.
Human T-lymphotropic virus type I (HTLV-I) is associated with adult T-cell leukemia/lymphoma and with a chronic degenerative myelopathy. However, another major type of HTLV, HTLV-H, has been isolated only sporadically, and little is known of disease associations, transmission routes, and risk factors for HTLV-II infection. Recent studies indicate that a high percentage of-certain groups of i.v. drug users and blood donors are infected with HTLV-II.Seroepidemiologic studies have found an elevated rate of seroreactivity to HTLV among Guaymi Indians from Bocas del Toro Province, Panama. To identify the cause of seroreactivity among this unique population we used HTLV-II-specific polymerase chain reaction techniques to detect HTLV genetic sequences from blood leukocytei of three seropositive Guaymi Indians. The HTLV-H primer-amplified polymerase chain reaction products from two of these, subjects were partially sequenced and matched published HTLV-H nucleotide sequences in both p24 gag (94% of 107 bases) andpol (98% of 112 bases) regions. A CD4+ T-lymphocyte line established from one of these same subjects produced HTLV-I1-speciflc proteins when tested in antigen-capture and immunoblot assays, as well as mature HTLV particles. The demonstration of HTLV-ll infection in this geographically and culturally isolated Central American Indian population without' typical risk factors of HTLV infection suggests that HTLV-H infection is endemic in this population and provides an important clue to a potential natural reservoir for this virus.
Hantavirus cardiopulmonary syndrome (HCPS), which is caused by infection with Choclo virus, is uncommon in Panama, yet seropositivity among rural residents is as high as 60%. To clarify the environmental risk factors favoring rodent-to-human transmission, we tested serum from 3,067 rodents captured over a five-year period for antibodies against recombinant N protein of hantavirus by enzyme immunoassay and strip immunoblot. Among 220 seropositive rodents, Oligoryzomys fulvescens, the reservoir of Choclo virus, had the highest overall seroprevalence (23.5%); more abundant rodents (Zygodontomys brevicauda and Sigmodon hirsutus) had lower seroprevalences. In the mixed (combined modern and traditional) productive agroecosystem, the highest seroprevalence was among O. fulvescens captured in residences and in crops grown within 40 meters of a residence, with significantly lower seroprevalence in adjacent pasture and non-productive vegetation. Thus, crop habitats may serve as refugia for invasion into adjacent human residences and suggests several interventions to reduce human infection.
The first identified outbreak of hantavirus pulmonary syndrome in Central America is described.
The first outbreak of hantavirus pulmonary syndrome (HPS) in Central America was documented on the Azuero peninsula of Panama in late 1999 and 2000. Reverse transcriptase-polymerase chain reaction evidence implicated only Choclo virus in symptomatic HPS with a mortality rate of 20%, although two rodent-borne hantaviruses (Choclo virus and Calabazo virus) were identified in the peridomestic habitat. Neighborhood serosurveys around case households found seroprevalence rates as high as 30%, the highest in the Americas except for western Paraguay. We report here population-based serosurveys for 1,346 adults and children in four communities, three on the Azuero peninsula and one in adjacent central Panama. Overall seroprevalence ranged from 33.2% in a population engaged in farming and fishing on Isla de Cañas, to 16.3% and 21.2% in two mainland agricultural communities, to 3.1% in central Panama, with a modest male predominance of 1.2:1. Nine percent of children 4-10 years old were seropositive, and seroprevalence increased with age in all communities, with highest levels of 52% in those 41-50 years old cohort on Isla de Cañas. Univariate analysis identified correlations between seroprevalence and multiple agricultural and animal husbandry activities. However, stepwise logistic regression models identified only raising animals (cows, pigs, goats, poultry) and fishing as significant independent variables. Human infection with hantavirus on the Azuero peninsula, either with Choclo virus or combined with Calabazo virus, is frequent but rarely results in hospitalization due to respiratory illnesses resembling HPS.
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