Highly Endemic, Waterborne Toxoplasmosis in North Rio de Janeiro State, Brazil

Lílian Maria Garcia Bahia-Oliveira, Jeffrey L. Jones, Juliana Azevedo-Silva, Cristiane C.F. Alves, Fernando Oréfice, David G. Addiss


Emerging Infectious Diseases. 2003;9(1) 

In This Article

Abstract and Introduction

In Campos dos Goytacazes, northern Rio de Janeiro state, Brazil, reports of uveitis consistent with toxoplasmosis led to a survey of the prevalence and risk factors for Toxoplasma gondii infection in 1997-1999. The survey population was selected randomly from schools, randomly chosen communities, and an army battalion. Serum samples from 1,436 persons were tested. With results adjusted for age, 84% of the population in the lower socioeconomic group was seropositive, compared with 62% and 23% of the middle and upper socioeconomic groups, respectively (p<0.001). When multivariate analysis was performed, drinking unfiltered water was found to increase the risk of seropositivity for the lower socioeconomic (odds ratio [OR]: 3.0, 95% confidence interval [CI] 1.3 to 6.9) and middle socioeconomic (OR: 1.7, 95% CI 1.2 to 2.3) populations. We also found a high T. gondii seroprevalence in this Brazilian community. Drinking unfiltered water increased the risk of T. gondii seropositivity, indicating the potential importance of oocyst transmission in water in this region.

Toxoplasmosis, a zoonotic protozoal disease caused by Toxoplasma gondii, is horizontally transmitted to humans by the accidental ingestion [1]of oocysts in cat feces or by eating raw or undercooked meat containing cysts[1]. The infection is prevalent throughout the world, affecting a large proportion of adults who usually have no symptoms. Vertical transmission of toxoplasmosis from an acutely infected pregnant woman can cause serious disease in the fetus[2]. In immunocompromised persons, a previously acquired T. gondii infection can be reactivated and result in severe illness, including encephalitis[3]. In some areas of Brazil, the serologic prevalence of T. gondii infection ranges from 50% to 80% of the adult population; the highest values are found in some northern and southern states[4]. In 1987, a survey of public school students in the capital of Rio de Janeiro State (Rio de Janeiro City) showed that the prevalence increased with age, reaching 71% for persons 16-20 years old[5]. However, in the rest of Rio de Janeiro State, little information exists on the epidemiology of toxoplasmosis.

Water has been identified as a source of T. gondii infection in outbreaks[6,7], but it has not been well studied as a risk factor in toxoplasmosis-endemic areas. We report the results of a seroprevalence survey in northern Rio de Janeiro State in which we assessed exposure to known sources of T. gondii infection, as well as exposure to various types of water.