Detection of Zika Virus in Oropharyngeal Swabs from Patients with Acute Febrile Illness.

The isolation of Zika virus (ZIKV) from serum of suspected human cases for diagnostic purposes can be challenging due to infrastructure constraints of laboratory testing technology. Therefore, as an alternative method, the objective of this study was to evaluate a random sample of oropharyngeal swabs for the diagnosis of ZIKV infection among patients with symptoms of arboviral and respiratory illness. The results revealed that ZIKV RNA could be detected by a reverse transcriptase polymerase chain reaction (RT-PCR) assay and isolated from oropharyngeal swabs from five of 38 samples, but serum samples from the same patients were negative for ZIKV by a variety of laboratory diagnostic approaches including RT-PCR and viral isolation followed by immunofluorescence assays. The findings suggested that the molecular detection and isolation of ZIKV in oropharyngeal swab warrants further study for consideration as an improved diagnostic procedure.

Individual and Spatial Risk of Dengue Virus Infection in Puerto Maldonado, Peru.

Dengue virus (DENV) affects more than 100 countries worldwide. Dengue virus infection has been increasing in the southern Peruvian Amazon city of Puerto Maldonado since 2000. We designed this study to describe the prevalence of past DENV infection and to evaluate risk factors. In 2012, we conducted a cross-sectional serosurvey and administered a knowledge, attitudes, and practices (KAP) questionnaire to members of randomly selected households. Sera were screened for antibodies to DENV by enzyme-linked immunosorbent assay and confirmed by plaque reduction neutralization test. We created indices for KAP (KAPi). We used SaTScan (Martin Kulldorff with Information Management Services Inc., Boston, MA) to detect clustering and created a multivariate model introducing the distance of households to potential vector and infection sources. A total of 505 participants from 307 households provided a blood sample and completed a questionnaire. Fifty-four percent of participants (95% confidence interval [CI]: 49.6; 58.5) had neutralizing antibodies to DENV. Higher values of KAPi were positively associated with having DENV antibodies in the multivariate analysis (odds ratio [ORII]: 1.6, 95% CI: 0.6, 2.4; ORIII: 2.7, 95% CI: 1.3, 5.5; and ORIV: 2.4, 95% CI: 1.2, 5.0). Older groups had lower chances of having been exposed to DENV than younger people (OR20-30: 0.5, 95% CI: 0.2, 0.8; OR31-45: 0.5, 95% CI: 0.3, 0.9; and OR>45: 0.6, 95% CI: 0.3, 1.3). Multivariate data analysis from the 270 households with location information showed male gender to have lower risk of past DENV infection (OR: 0.6, 95% CI: 0.4, 0.9). We conclude that risk of DENV infection in Puerto Maldonado is related to gender, age of the population, and location.

Endemic eastern equine encephalitis in the Amazon region of Peru.

Eastern equine encephalitis virus (EEEV) causes severe neurologic disease in North America, but only two fatal human cases have been documented in South America. To test the hypothesis that alphavirus heterologous antibodies cross-protect, animals were vaccinated against other alphaviruses and challenged up to 3 months later with EEEV. Short-lived cross-protection was detected, even in the absence of cross-neutralizing antibodies. To assess exposure to EEEV in Peru, sera from acutely ill and healthy persons were tested for EEEV and other alphavirus antibodies, as well as for virus isolation. No EEEV was isolated from patients living in an EEEV-enzootic area, and only 2% of individuals with febrile illness had EEEV-reactive IgM. Only 3% of healthy persons from the enzootic region had EEEV-neutralizing antibodies. Our results suggest that humans are exposed but do not develop apparent infection with EEEV because of poor infectivity and/or avirulence of South American strains.

Evidence of rickettsial and leptospira infections in Andean northern Peru.

Between May and October 2002, a cluster of acute febrile illnesses occurred in the subtropical Andean foothills of Peru. Serologic evidence in villages where disease had been documented showed that the prevalence of IgM antibody to Leptospira ranged from 6% to 52%, that of IgM antibody to spotted fever group (SFG) rickettsia ranged from 10% to 19%, and that of IgM antibody to Coxiella burnetii from 1% to 15%. Measurement of IgG antibodies for SFG rickettsiae suggested that this disease was endemic. In contrast, IgG antibodies against C. burnetii were largely absent. In humans, microagglutination tests identified pathogenic variants of Leptospira. The presence of an SFG rickettsial infection was confirmed in four febrile patients following polymerase chain reaction and sequencing of the conserved 17-kD common antigen gene (htrA). Collectively, these analyses indicated that Rickettsia sp., C. burnetii, and Leptospira sp. were circulating in the region during the time of disease outbreak and implicate the involvement of an as yet undetermined SFG rickettsia in northwestern Peru.