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Respiratory infections are one of the most frequent reasons for medical consultations in children. In low resource settings such as in Lao People's Democratic Republic, knowledge gaps and the dearth of laboratory capacity to support differential diagnosis may contribute to antibiotic overuse. We studied the etiology, temporal trends, and genetic diversity of viral respiratory infections in children to provide evidence for prevention and treatment guidelines. From September 2014 to October 2015, throat swabs and nasopharyngeal aspirates from 445 children under 10 years old with symptoms of acute respiratory infection were collected at the Children Hospital in Vientiane. Rapid antigen tests were performed for influenza A and B and respiratory syncytial virus. Real‐time reverse‐transcription polymerase chain reactions (RT‐PCRs) were performed to detect 16 viruses. Influenza infections were detected with a higher sensitivity using PCR than with the rapid antigen test. By RT‐PCR screening, at least one pathogen could be identified for 71.7% of cases. Human rhinoviruses were most frequently detected (29.9%), followed by influenza A and B viruses combined (15.9%). We identify and discuss the seasonality of some of the infections. Altogether these data provide a detailed characterization of respiratory pathogens in Lao children and we provide recommendations for vaccination and further studies.

In Lao People's Democratic Republic (PDR), acute respiratory infections overburden the health care system, but viral etiology, genetic diversity, and seasonality, especially in light of the introduction of influenza vaccination in the country, are poorly understood. From August 2010 to April 2011, 309 outpatients were recruited at the Luang Prabang Provincial Hospital covering highland Lao communities. Nasopharyngeal swabs were screened for the presence of 13 respiratory viruses. At least one virus was detected in 69.6% and dual/triple viral infections in 12.9%/1.9% of the patients. Influenza A and B viruses combined were the most frequently detected pathogens, followed by human adenovirus and respiratory syncytial virus (RSV). The other viruses were detected in less than 10% of the patients. Phylogenetic analyses on a representative set of RSV strains revealed that, while otherwise very rare, the RSV-B CB1/THB genotype cocirculated with other common genotypes. A single wave of influenza virus and RSV activity was observed during the rainy season, providing further support to influenza vaccination before the onset of the rains. This study provides recommendations for influenza vaccination that still needs optimization and highlights the need for revised guidelines for treatment and prevention of respiratory infections in Lao PDR, as well as for increased surveillance efforts.

Between September 2014 and December 2015, 298 sera from rash and fever patients from all over Cuba were investigated for specific IgM antibodies against measles, rubella, dengue, human parvovirus B19 (B19V) and human herpesvirus 6 (HHV6) using a commercial enzyme-linked immunosorbent assay kits. B19V IgM positive and equivocal samples were investigated by a polymerase chain reaction and genotyping. No measles, rubella or dengue cases were detected. HHV6-IgM antibodies were confirmed in 5.7% and B19V-IgM antibodies in 10.7% of the patients. A total of 31.3% of the B19V cases were between 5 and 9 years old and 34.4% were 20 years and older. The only B19V sequence obtained belonged to genotype 1a. Diagnosis was established for only 16% of the rash and fever patients, suggesting that other diseases such as Zika or Chikungunya may play a role.

Institute of Immunology, Centre de Recherche Public-Sante´/National Public Health Laboratory, Luxembourg,LuxembourgHuman parvovirus B19 (B19V) infection in im-munocompetent patients usually has a mildclinical course, but during pregnancy it cancause serious and even fatal complications inthe fetus. The most common clinical presenta-tion of B19V infection is erythema infectiosumand in this case laboratory confirmation is re-quired for differentiation from other exanthem-atous diseases. Measles and rubella negativesera collected in Belarus between 2005 and2008 from 906 patients with a rash and feverwere screened for B19V infection by ELISA.More than 35% of the samples (322/906) werepositive for B19V. The proportion ranged from10.1% in 2008 to 53.2% in 2006 when anoutbreak took place in Minsk city. All B19Voutbreaks and cluster cases occurred duringthe winter–spring period, but sporadic caseswere recorded basically throughout the year.The majority of the cases (56.5%) occurredamong the 2 till 10 year old children, and 27.3%of the cases were observed in adults between19 and 53 years. All 104 B19V strainssequenced in the NS1/VP1u region belonged togenotype 1 with a maximal genetic distance of1.75%. The two phylogenetic clusters reflectedthe geographic origins of the viruses within thecountry. Forty-two unique nucleotide mutationsas compared to sequences downloadedfrom GenBank were found in the VP1u andNS1 regions; most of these changes werenonsynonymous. This report highlights theimportance of B19V infection in patients witha rash and fever in Belarus. J. Med. Virol.84:973–978, 2012.

In Western Africa, hepatitis B virus (HBV) genotype E predominates throughout a vast crescent spanning from Senegal to Namibia and at least to the Central African Republic to the East. Although from most of the eastern parts of sub-Saharan Africa only limited sets of strains have been characterized, these belong predominantly to genotype A. To study how far the genotype E crescent extends to the East, a larger number of HBV strains from Rwanda were analyzed. Phylogenetic analysis of 45 S fragment sequences revealed strains of genotypes A (n = 30), D (n = 10), C (n = 4), and B (n = 1). Twelve genotype A sequences formed a new cluster clearly separated from the reference strains of the known sub-genotypes. Thus, with four genotypes and at least six sub-genotypes and a new cluster of genotype A strains, HBV shows an exceptional genetic variability in this small country, unprecedented in sub-Saharan Africa. Despite this exceptional genetic variability, not a single genotype E virus was found indicating that this country does not belong to the genotype E crescent, but is east of an emerging African genotype E/A1 divide.

The nucleoprotein genes of 49 measles virus (MV) strains circulating in Russia between 2000 and 2006 and in Vietnam in 2003 were analyzed by genotype-specific PCR and the results were compared with their sequences. The sequences revealed the presence of genotypes H1 and H2 in the center (Nha Trang) and the north (Hanoi) of Vietnam, respectively. The relative diversity of the H2 strains suggested an endemic circulation of these viruses in the capital. In contrast genotype H1 strains from Nha Trang were homogenous genetically, which may indicate a recent importation. The strains obtained from 12 different regions of the Russian Federation were assigned to the genotypes H1, D4, and D6. Most strains (81.4%) were correctly genotyped by a multiplex PCR method which was sensitive to genotype-specific mutations [Kremer et al. (2004): J Clin Microbiol 42: 3017-3022]. Ambiguous or negative results for some clade H and genotype D6 strains were due to point mutations in the type-specific primer binding sites. After exchanging a single nucleotide in both the clade H- and the genotype D6-specific primers, all strains were assigned correctly to their genotype. A simplified procedure for use in Vietnam was developed to distinguish directly between genotypes H1 and H2 and any non-H genotype. These results demonstrate that our multiplex PCR method can be adapted easily to new sequence variants or specific epidemiological situations, and thus be very useful for rapid genotyping of large number of samples even in laboratories which do not have sequencing facilities.

Isolates of hepatitis B viruses were collected from 20 acute and chronic hepatitis patients in a highly endemic region of Nigeria. Sequencing classified the isolates to the ayw4, as they all contained the amino acid variations characteristic for that serotype. In the pre-S2 region of five isolates, three to seven amino acids were deleted, suggesting that immune escape mutations previously associated only with chronic HBV infection may be observed also in acute disease. Phylogenetic analysis of the complete pre-S2/S (large S) genes (831 nt) demonstrated that all the viruses belonged to the same genotype E. So far, no isolates of genotype E have been found in any other region of the world, including the Americas. This may suggest a relatively recent introduction of this genotype into humans and would explain the relatively low genetic diversity of viruses belonging to this genotype. One genotype E virus had been found previously in a chimpanzee, and viruses belonging to the CHIMP genotype are related to other genotype E viruses. These findings are compatible with a transmission of genotype E viruses from chimpanzees to humans. J. Med. Virol. 65:463–469, 2001. © 2001 Wiley-Liss, Inc.

The neutralization capacity of sera from Luxembourgian adolescent vaccinees and from Nigerian women with measles-induced immunity to a number of measles virus strains was compared. Although both cohorts were matched for their hemagglutination inhibition and standard neutralization titers, 12 of the 22 late convalescent sera, and only 6 of 24 vaccinees neutralized all viruses. Similarly, only 2 of 20 viruses were not neutralized by at least 75% of late convalescent sera, in comparison to 10 of 20 viruses that resisted neutralization by at least 75% of the vaccinees. The more resistant viruses were not limited to a certain clade. One Nigerian virus was resistant to neutralization by 30% of the late convalescent women and by 75% of vaccinees. These results suggest that qualitative differences in neutralizing antibodies may reduce further protection of infants by passively acquired immunity against wild-type viruses when vaccinated girls become mothers.

Serological evidence indicates that measles virus (MV) could circulate in seropositive, fully protected populations. Among individuals fully protected against disease, those prone to asymptomatic secondary immune response are the most likely to support subclinical MV transmission. The serological characteristics of protected subjects who developed secondary immune response after reexposure to measles have been described recently [Huiss et al. (1997): Clinical and Experimental Immunology 109:416-420]. On the basis of these data, a threshold of susceptibility was defined to estimate frequencies of secondary immune response competence in different populations. Among measles, late convalescent adults (n = 277) and vaccinated high school children (n = 368), 3.2-3.9% and 22.2-33.2%, respectively, were considered susceptible to secondary immune response. A second vaccination did not seem to lower this incidence. Even when estimates of symptomatic secondary immune response (e.g., secondary vaccine failure) were taken into account, susceptibility to subclinical secondary immune response was still 5-8 times higher after vaccination than after natural infection. Although viral transmission between protected individuals has never been directly demonstrated, the data describe a population in which protected but infectious persons could potentially be of epidemiological importance.