High seroprevalence of hantavirus infection on the Azuero peninsula of Panama.

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.

Serosurvey of wild rodents for hantaviruses in Panama, 2000-2002.

Five hundred fifty-six samples representing 24 species of small mammals (two species of marsupials and 22 rodents) were collected in Panama between February 2000 and July 2002. The samples were examined for antibodies to hantaviruses by means of enzyme-linked immunosorbent assay or immunoblot assays. The serologic results indicated that several rodent species might act as hantaviral reservoirs in Panama: Costa Rican pygmy rice rat (Oligoryzomys fulvescens costaricensis), four positive of 72 tested (5.6%); Cherrie's cane rat (Zygodontomys brevicauda cherriei), five of 108 (4.6%); Mexican deer mouse (Peromyscus mexicanus), one of 22 (5%); Mexican harvest mouse (Reithrodontomys mexicanus), one of seven (14%); Chiriquí harvest mouse (Reithrodontomys creper), one of two (50%); and Sumichrast's harvest mouse (Reithrodontomys sumichrasti), three of four (75%). Hantavirus infection in Peromyscus mexicanus and the three species of Reithrodontomys was caused by Rio Segundo hantavirus, a species of virus not previously reported from Panama. At least three hantaviruses, therefore, are known to infect populations of wild rodents in the country. However, given the total number of animals tested, the role of these rodent species in the epidemiology and epizootiology of hantavirus infections remains unclear.