Outbreak of Febrile Respiratory Illness Associated with Adenovirus 11a Infection in a Singapore Military Training Camp▿

Outbreak cases of acute respiratory disease (ARD) associated with subspecies B2 human adenovirus 11a (HAdV-11a) infection were detected during 2005 in a military basic training camp in Singapore. The Singapore HAdV-11a strain is highly similar to other Asian strains of HAdV-11, including strain QS-DLL, which is responsible for the recently described 2006 outbreak of ARD in China

Adenovirus Microsatellite Reveals Dynamics of Transmission during a Recent Epidemic of Human Adenovirus Serotype 14 Infection▿

This study reveals diverse-length polymorphisms in long mononucleotide repeats (microsatellites) in several serotypes of epidemic human respiratory adenovirus. The length of one of these microsatellites, a homopolymeric thymidine [poly(T)] repeat, is measured in 68 isolates of adenovirus serotype 14. These isolates were collected during a series of sudden and sometimes fatal outbreaks among both military recruits and civilians as the virus emerged for the first time in the United States in 2006 and 2007. The results demonstrate the usefulness of adenoviral microsatellites as high-resolution molecular strain markers. The described homopolymer is hypervariable in length, varying from 12 to 17 bp in the analyzed sample set. All intermediate lengths were identified in at least one isolate. Furthermore, the specific length of the marker is stable for significant periods of time (up to 7 months) at individual sites where the virus is in consistent circulation. The microsatellite also can maintain specific length identity through site-to-site transmission events, as determined by the analysis of isolates from three advanced training sites that appeared to be subject to pathogen transfer from one of the affected recruit training installations. Public database searches revealed that the polymorphic nature of the microsatellite extends to other species B serotypes, and that other polymorphic microsatellites can be identified readily in a variety of epidemic respiratory adenovirus clades. This study shows that microsatellites are a ubiquitous source of polymorphic markers for human adenoviruses and demonstrates their use through an epidemiological analysis of isolates from a recent North American epidemic

Diagnostic Approach to Acute Diarrheal Illness in a Military Population on Training Exercises in Thailand, a Region of Campylobacter Hyperendemicity▿

High rates of Campylobacter fluoroquinolone resistance highlight the need to evaluate diagnostic strategies that can be used to assist with clinical management. Diagnostic tests were evaluated with U.S. soldiers presenting with acute diarrhea during deployment in Thailand. The results of bedside and field laboratory diagnostic tests were compared to stool microbiology findings for 182 enrolled patients. Campylobacter jejuni was isolated from 62% of the cases. Clinical and laboratory findings at the time of presentation were evaluated to determine their impact on the posttest probability, defined as the likelihood of a diagnosis of Campylobacter infection. Clinical findings, the results of tests for inflammation (stool occult blood testing [Hemoccult], fecal leukocytes, fecal lactoferrin, plasma C-reactive protein), and the numbers of Campylobacter-specific antibody-secreting cells in peripheral blood failed to increase the posttest probability above 90% in this setting of Campylobacter hyperendemicity when these findings were present. Positive results by a Campylobacter-specific commercial enzyme immunoassay (EIA) and, less so, a research PCR were strong positive predictors. The negative predictive value for ruling out Campylobacter infection, defined as a posttest probability of less than 10%, was similarly observed with these Campylobacter-specific stool-based tests as well the fecal leukocyte test. Compared to the other tests evaluated, the Campylobacter EIA is a sensitive and specific rapid diagnostic test that may assist with diagnostic evaluation, with consideration of the epidemiological setting, logistics, and cost

Differing influences of virus burden and immune activation on disease severity in secondary dengue-3 virus infections

Dengue hemorrhagic fever (DHF), the most severe form of illness following infection with a dengue virus, is characterized by plasma leakage, thrombocytopenia, and hepatic inflammation. The interrelationships among virus burden, immune activation, and development of DHF were examined in 54 children with secondary dengue-3 virus infections participating in a prospective, hospital-based study. DHF was associated with higher mean plasma viremia early in illness and earlier peak plasma interferon-gamma levels. Maximum plasma viremia levels correlated with the degree of plasma leakage and thrombocytopenia. Maximum plasma levels of interleukin (IL)-10 and soluble tumor necrosis factor receptor-II correlated with the degree of thrombocytopenia, independently of viremia levels. Hepatic transaminase elevation correlated with plasma soluble IL-2 receptor levels and not with viremia levels. Quantitative differences in virus burden and host immune responses, and the timing of type 1 cytokine responses, have differing influences on the severity of disease manifestations during secondary dengue-3 virus infections

Detection of Shigella by a PCR Assay Targeting the ipaH Gene Suggests Increased Prevalence of Shigellosis in Nha Trang, Vietnam

Shigella spp. are exquisitely fastidious gram-negative organisms which frequently escape detection by traditional culture methods. To get a more complete understanding of the disease burden caused by Shigella in Nha Trang, Vietnam, real-time PCR was used to detect Shigella DNA. Randomly selected rectal swab specimens from 60 Shigella culture-positive patients and 500 Shigella culture-negative patients detected by population-based surveillance of patients seeking care for diarrhea were processed by real-time PCR. The target of the primer pair is the invasion plasmid antigen H gene sequence (ipaH), carried by all four Shigella species and enteroinvasive Escherichia coli. Shigella spp. could be isolated from the rectal swabs of 547 of 19,206 (3%) patients with diarrhea. IpaH was detected in 55 of 60 (93%) Shigella culture-positive specimens, whereas it was detected in 87 of 245 (36%) culture-negative patients free of dysentery (P < 0.001). The number of PCR cycles required to detect a PCR product was highest for culture-negative, nonbloody diarrheal specimens (mean number of cycles to detection, 36.6) and was lowest for children with culture-positive, bloody diarrheal specimens (mean number of cycles, 25.3) (P < 0.001). The data from real-time PCR amplification indicate that the culture-proven prevalence of Shigella among patients with diarrhea may underestimate the prevalence of Shigella infections. The clinical presentation of shigellosis may be directly related to the bacterial load