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Drinking water contamination is a frequent problem in developing countries and could be associated with bacterial pathogen carriage in feces. We evaluated the association between the risk of drinking water and bacterial carrier status in children younger than 5 years in a cross-sectional study conducted in 199 households from three Peruvian rural communities. Fecal samples from children were screened for pathogenic Aeromonas, Campylobacter, and Vibrio species, as well as for Enterobacteriaceae, including pathogenic Escherichia coli. The drinking water risk was determined using E. coli as an indicator of contamination. Nineteen (9.5%) children were colonized with pathogens and classified as carriers, all without diarrhea symptoms. Of 199 drinking water samples, 38 (19.1%) were classified as very high risk because of high fecal contamination (> 100 E. coli/100 mL). Shared-use water sources, daily washing of containers, and washing using only water were associated with higher prevalence of bacterial carriage, whereas there was no association between households reporting boiling and chlorination of water and carrier status. The prevalence of carriage in children exposed to very high-risk water was 2.82 (95% CI: 1.21-6.59) times the prevalence of those who consumed less contaminated water, adjusted by the water source and daily washing. Our results suggest that household drinking water plays an important role in the generation of carriers with diarrheal pathogens. Our findings also highlight the importance of interventions to ensure the safety of drinking water. Further studies are needed to validate the observed association and determine its significance with respect to diarrhea in the community.

Rickettsia and Leptospira spp. are under-recognized causes of acute febrile disease worldwide. Rickettsia species are often placed into the spotted fever group rickettsiae (SFGR) and typhus group rickettsiae (TGR). We explored the antibody prevalence among humans for these two groups of rickettsiae in four regions of Peru (Lima, Cusco, Puerto Maldonado, and Tumbes) and for Leptospira spp. in Puerto Maldonado and Tumbes. We also assessed risk factors for seropositivity and collected serum samples and ectoparasites from peri-domestic animals from households in sites with high human seroprevalence. In total, we tested 2,165 human sera for antibodies (IgG) against SFGR and TGR by ELISA and for antibodies against Leptospira by a microscopic agglutination test. Overall, human antibody prevalence across the four sites was 10.6% for SFGR (ranging from 6.2% to 14.0%, highest in Tumbes) and 3.3% for TGR (ranging from 2.6% to 6.4%, highest in Puerto Maldonado). Factors associated with seroreactivity against SFGR were male gender, older age, contact with backyard birds, and working in agriculture or with livestock. However, exposure to any kind of animal within the household decreased the odds ratio by half. Age was the only variable associated with higher TGR seroprevalence. The prevalence of Leptospira was 11.3% in Puerto Maldonado and 5.8% in Tumbes, with a borderline association with keeping animals in the household. We tested animal sera for Leptospira and conducted polymerase chain reaction (PCR) to detect Rickettsia species among ectoparasites collected from domestic animals in 63 households of seropositive participants and controls. We did not find any association between animal infection and human serostatus.

Here we report the first incidence of New Delhi metallo-β-lactamase (NDM-1)–producing Acinetobacter baumannii in Peru, identified via a strain-based nosocomial surveillance project carried out in Lima and Iquitos. The blaNDM-1 gene was detected by multiplex polymerase chain reaction (PCR) and confirmed by loci sequencing. Acinetobacter baumannii is a nearly ubiquitous and promiscuous nosocomial pathogen, and the acquisition of blaNDM-1 by A. baumannii may facilitate an increase in the prevalence of this important resistance marker in other nosocomial pathogens.

Leptospirosis is a neglected zoonotic disease with worldwide endemicity and continues to be a significant public health burden on resource-limited populations. Previously, we produced three highly purified recombinant antigens (rLipL32, rLipL41, and rLigA-Rep) and evaluated their performance of detecting Leptospira-specific antibodies in enzyme-linked immunosorbent assay (ELISA) as compared with the microscopic agglutination test (MAT). The overall sensitivity of this assay approached 90%. Recently, another recombinant antigen (rLigB-Rep) was prepared. We tested each individual antigen and a 1:1:1:1 mixture of these four antigens for the detection of Leptospira-specific antibodies in ELISA. The performance of these recombinant antigens was evaluated with a much larger febrile patient panel (337 MAT-confirmed positive sera and 92 MAT-negative sera from febrile patients). Combining the detection results of immunoglobulin M and immunoglobulin G from these four individual antigens, the overall sensitivity was close to 90% but the specificity was only 66%, based on the MAT reference method. The overall sensitivity and specificity of the four-antigen mixture were 82% and 86%, respectively. The mixture of four antigens also exhibited a broader reactivity with MAT-positive samples of 18 serovars from six major pathogenic Leptospira species. Given the limitations of MAT, the data were further analyzed by Bayesian latent class model, showing that ELISA using a 1:1:1:1 mixture still maintained high sensitivity (79%) and specificity (88%) as compared with the sensitivity (90%) and specificity (83%) of MAT. Therefore, ELISA using a mixture of these four antigens could be a very useful test for seroprevalence studies.

We produced three highly purified recombinant antigens rLipL32, rLipL41, and rLigA-Rep (leptospiral immunoglobulin-like A repeat region) for the detection of Leptospira-specific antibodies in an enzyme-linked immunosorbent assay (ELISA). The performance of these recombinant antigens was evaluated using 121 human sera. Among them, 63 sera were microscopic agglutination test (MAT)-confirmed positive sera from febrile patients in Peru, 22 sera were indigenous MAT-negative febrile patient sera, and 36 sera were from patients with other febrile diseases from Southeast Asia, where leptospirosis is also endemic. Combining the results of immunoglobulin M (IgM) and IgG detection from these three antigens, the overall sensitivity is close to 90% based on the MAT. These results suggest that an ELISA using multiple recombinant antigens may be used as an alternative method for the detection of Leptospira-specific antibodies.

We investigated the etiology of acute diarrhea among Peruvian military recruits undergoing three months of basic combat training near the Amazonian city of Iquitos. From January through September 2002, 307 of 967 recruits were seen at the Health Post for diarrhea (attack rate [AR] = 31.8%, incidence = 1.28 95% confidence interval [CI] = 1.14-1.43] episodes/person-year). Shigella spp. were the most common bacterial pathogen recovered from recruits experiencing diarrhea episodes. These bacteria were isolated from 89 (40%) of 225 diarrheal stools examined (AR = 7.6%, incidence = 0.30 [95% CI = 0.24-0.38] episodes/person-year). Most (83 of 90; 92%) of the Shigella isolates were S. flexneri, of which 57 (69%) were serotype 2a. Seventy-six percent of Shigella isolates were resistant to sulfamethoxazole/trimethoprim and all were sensitive to ciprofloxacin. Peruvian soldiers may be an excellent population in which to test the efficacy of S. flexneri vaccines in advanced development.

While studying chronic verruga peruana infections in Peru from 2003, we isolated a novel Bartonella agent, which we propose be named Candidatus Bartonella ancashi. This case reveals the inherent weakness of relying solely on clinical syndromes for diagnosis and underscores the need for a new diagnostic paradigm in developing settings.

Background Leptospirosis is a potentially lethal zoonosis mainly affecting low-resource tropical countries, including Peru and its neighbouring countries. Timely diagnosis of leptospirosis is critical but may be challenging in the regions where it is most prevalent. The serodiagnostic gold standard microagglutination test (MAT) may be technically prohibitive. Our objective in this study was to assess the sensitivity, specificity, and predictive value of an IgM antibody capture enzyme-linked immunoassay (MAC-ELISA) derived from the M20 strain of Leptospira interrogans serovar Copenhageni (M20) by comparison to MAT, which was used as the gold standard method of diagnosis. Methods Acute and convalescent sera from participants participating in a passive febrile surveillance study in multiple regions of Peru were tested by both IgM MAC-ELISA and MAT. The sensitivity, specificity, positive and negative predictive value (PPV, NPV) of the MAC-ELISA assay for acute, convalescent and paired sera by comparison to MAT were calculated. Results The sensitivity, specificity, PPV and NPV of the MAC-ELISA assay for acute sera were 92.3%, 56.0%, 35.3% and 96.6% respectively. For convalescent sera, the sensitivity, specificity, PPV and NPV of the MAC-ELISA assay were 93.3%, 51.5%, 63.6% and 89.5% respectively. For paired sera, the sensitivity, specificity, PPV and NPV of the MAC-ELISA assay were 93.6%, 37.5%, 59.2%, 85.7% respectively. Conclusions The M20 MAC-ELISA assay performed with a high sensitivity and low specificity in the acute phase of illness. Sensitivity was similar as compared with MAT in the convalescent phase and specificity remained low. Paired sera were the most sensitive but least specific by comparison to MAT serodiagnosis. NPV for acute, convalescent and paired sera was high. The limited specificity and high sensitivity of the MAC-ELISA IgM suggests that it would be most valuable to exclude leptospirosis in low-resource regions that lack immediate access to definitive reference laboratory techniques such as MAT.