Toxoplasma gondii, Brazil

We thank Dr Gomez-Marin for his letter regarding our article on recently acquired Toxoplasma gondii infection in Brazil (1). Dr Gomez-Marin states that perhaps age could account for our finding that having had children was a risk factor for recent T. gondii infection among women. Studies have shown that age is a risk factor for prevalent T. gondii infection; i.e., infection prevalence increases with age (2). However, age is not necessarily a risk factor for recent (incident) infection. 
 
Our study of risk factors for T. gondii infection was a case-control design to evaluate recent infection, not a cross-sectional study of T. gondii infection prevalence in a population. In our study, case-patients with recent infection were similar in age to T. gondii–negative control-patients, although among women the mean age of case-patients (33 years) differed slightly from that of control-patients (29 years) (p = 0.03, t-test). In addition, multivariate analysis comparing the case-patients with control-patients showed that age was not a significant factor. However, when we kept age in the multivariate model for women (p = 0.87 for age in the model), the odds ratio for having had children changed little, from 14.94 (95% confidence interval [CI] 3.68–60.73) to 14.01 (95% CI 2.88–68.08). Therefore, we do think that, in this study population, having had children is a risk factor for T. gondii infection among women. 
 
Dr Gomez-Marin also states that we did not evaluate drinking water–related factors. However, in our methods section (1), we indicated that our questionnaire asked about a comprehensive set of risk factors related to drinking water. Specifically, the questionnaire asked about the types of water (city, private well, and others, including bottled water); chlorination; filtering of water; and ingestion of water from streams, lakes, rivers, ponds, or other sources. Although we evaluated numerous water-related factors, we did not find them to be significant in this study, which applies to 1 area of Brazil. In other areas of Brazil, however, studies in which 1 of our authors (J.L.J.) has been involved have found water to be a risk factor or a source of infection (2,3).

(H5N1) virus, suggestive of a cohort effect or otherwise, have yet to be published, although anecdotal reports of completed surveys point to a lack of widespread human infection with the virus (8). Current evidence indicates that pandemic influenza of humans since 1918 has been restricted to 3 influenza A virus subtypes: H1 (1918-57 and 1977-present); H2 (1957-68); and H3 (1968-present) (9,10). If an element of immunity to avian influenza A (H5N1) does exist in older populations, its possible association with geographically widespread (intercontinental) influenza A events before the late 1960s merits further investigation. The (1). They did not, however, control for age. Previous seroepidemiologic studies have shown that age is a main confounding variable in analysis of risk factors for toxoplasmosis (2). Age can explain why mothers with more children are at higher risk for toxoplasmosis; the longer persons live in areas with high toxoplasmosis prevalence, the higher their risk for infection.
Also not explored were drinking water-related factors. Our recent study of pregnant women in Quindio, Colombia, found factors that explained attributable risk percent for infection to be eating rare meat (0.26%) and having contact with a cat <6 months of age (0.19%) (3). Drinking bottled water was more significantly protective for the group that did not consume undercooked or raw meat (odds ratio 0.06, 95% confidence interval 0.006-0.560, p = 0.008). We think that drinking water-related factors could explain up to 50% of toxoplasmosis infections in our region.
In response: We thank Dr Gomez-Marin for his letter regarding our article on recently acquired Toxoplasma gondii infection in Brazil (1). Dr Gomez-Marin states that perhaps age could account for our finding that having had children was a risk factor for recent T. gondii infection among women. Studies have shown that age is a risk factor for prevalent T. gondii infection; i.e., infection prevalence increases with age (2). However, age is not necessarily a risk factor for recent (incident) infection.
Our study of risk factors for T. gondii infection was a case-control design to evaluate recent infection, not a cross-sectional study of T. gondii infection prevalence in a population. In our study, case-patients with recent infection were similar in age to T. gondii-negative control-patients, although among women the mean age of case-patients (33 years) differed slightly from that of control-patients (29 years) (p = 0.03, t-test). In addition, multivariate analysis comparing the case-patients with control-patients showed that age was not a significant factor. However, when we kept age in the multivariate model for women (p = 0.87 for age in the model), the odds ratio for having had children changed little, from 14.94 (95% confidence interval [CI] 3.68-60.73) to 14.01 (95% CI 2.88-68.08). Therefore, we do think that, in this study population, having had children is a risk factor for T. gondii infection among women.
Dr Gomez-Marin also states that we did not evaluate drinking water-related factors. However, in our methods section (1), we indicated that our questionnaire asked about a comprehensive set of risk factors related to drinking water. Specifically, the questionnaire asked about the types of water (city, private well, and others, including bottled water); chlorination; filtering of water; and ingestion of water from streams, lakes, rivers, ponds, or other sources. Although we evaluated numerous water-related factors, we did not find them to be significant in this study, which applies to 1 area of Brazil. In other areas of Brazil, however, studies in which 1 of our authors (J.L.J.) has been involved have found water to be a risk factor or a source of infection (2,3).
Again, we thank Dr Gomez-Marin for his letter. We sincerely appreciate his interest and work with toxoplasmosis.

CTX-M Extendedspectrum β β-Lactamases, Washington State
To the Editor: The CTX-M-type β-lactamases are non-TEM and non-SHV plasmid-mediated, class A, extended-spectrum β-lactamases (ESBLs). The CTX-M-type β-lactamases have recently emerged as the most common type of ESBLs, with a global distribution (1). In contrast, the CTX-M-type ESBLs are rarely reported in the United States and have not been identified in pathogens iso-lated from infected patients with gastroenteritis.
We screened 637 Salmonella and 126 Shigella isolates, collected in the state of Washington during 2003-2004, for CTX-M-type β-lactamases. Of these, 60 Salmonella isolates that exhibited an ESBL phenotype were further characterized by PCR for TEV, SHV, CTM-X, and CMY. All were positive for the CMY-2 or TEM-1 β-lactam genes. One Shigella sonnei isolate (WA7593), cultured from a fecal specimen in August 2004, tested positive with an ESBL confirmatory disk diffusion panel (ceftazidime 24 mm, ceftazidime/clavulanate 32 mm, cefotaxime 14 mm, and cefotaxime/clavulanate 34 mm; [2]). The patient had recently traveled to Pakistan and likely became ill there and returned to the United States while still sick. The transfer of extended-spectrum cephalosporin resistance was tested by conjugation to Escherichia coli J53 azi R (3). The MIC for S. sonnei WA7593 and its transconjugant, WA7593TC1, were tested by using the E-test (AB Biodisk, Solna, Sweden). Both strains were resistant to cefotaxime and susceptible to ceftazidime and showed almost the same antimicrobial susceptibility patterns as β-lactam antimicrobial drugs (Table).
The type of ESBL produced by these strains was determined by using PCR specific for TEM and CTX-M (4,5). Both strains were PCR positive for TEM and CTX-M. The TEM type PCR products were then sequenced and identified as TEM-1; no variation was found on the promoter region of bla TEM-1 . The entire sequence of bla CTX-M from WA7593 was then sequenced (1), and the product showed 100% homology with bla CTX-M-15 (GenBank accession no. AY960984). The mobile element associated with the transfer of bla CTX-M-15 was investigated by sequencing the flanking regions.