Rapid-Test Based Identification of Influenza as an Etiology of Acute Febrile Illness in Cambodia

Influenza can be manifested as an acute febrile illness, with symptoms similar to many pathogens endemic to Cambodia. The objective of this study was to evaluate the Quickvue influenza A+B rapid test to identify the etiology of acute febrile illness in Cambodia. During December 2006–May 2008, patients enrolled in a study to identify the etiology of acute febrile illnesses were tested for influenza by real-time reverse transcriptase PCR (RT-PCR) and Quickvue influenza A+B rapid test. The prevalence of influenza was 19.7% by RT-PCR. Compared with RT-PCR, the sensitivity and specificity of the rapid test were 52.1% and 92.5%, respectively. The influenza rapid test identified the etiology in 10.2% of enrollees and ≥ 35% during peak times of influenza activity. This study suggests that rapid influenza tests may be useful during peak times of influenza activity in an area where several different etiologies can present as an acute febrile illness

Infectious Etiologies of Acute Febrile Illness among Patients Seeking Health Care in South-Central Cambodia

The agents of human febrile illness can vary by region and country suggesting that diagnosis, treatment, and control programs need to be based on a methodical evaluation of area-specific etiologies. From December 2006 to December 2009, 9,997 individuals presenting with acute febrile illness at nine health care clinics in south-central Cambodia were enrolled in a study to elucidate the etiologies. Upon enrollment, respiratory specimens, whole blood, and serum were collected. Testing was performed for viral, bacterial, and parasitic pathogens. Etiologies were identified in 38.0% of patients. Influenza was the most frequent pathogen, followed by dengue, malaria, and bacterial pathogens isolated from blood culture. In addition, 3.5% of enrolled patients were infected with more than one pathogen. Our data provide the first systematic assessment of the etiologies of acute febrile illness in south-central Cambodia. Data from syndromic-based surveillance studies can help guide public health responses in developing nations

Genetic Characterization of Zika Virus Strains: Geographic Expansion of the Asian Lineage

Zika virus (ZIKV) is a mosquito-transmitted flavivirus found in both Africa and Asia. Human infection with the virus may result in a febrile illness similar to dengue fever and many other tropical infections found in these regions. Previously, little was known about the genetic relationships between ZIKV strains collected in Africa and those collected in Asia. In addition, the geographic origins of the strains responsible for the recent outbreak of human disease on Yap Island, Federated States of Micronesia, and a human case of ZIKV infection in Cambodia were unknown. Our results indicate that there are two geographically distinct lineages of ZIKV (African and Asian). The virus has circulated in Southeast Asia for at least the past 50 years, whereupon it was introduced to Yap Island resulting in an epidemic of human disease in 2007, and in 2010 was the cause of a pediatric case of ZIKV infection in Cambodia. This study also highlights the danger of ZIKV introduction into new areas and the potential for future epidemics of human disease

Little evidence of subclinical avian influenza virus infections among rural villagers in Cambodia.

In 2008, 800 adults living within rural Kampong Cham Province, Cambodia were enrolled in a prospective cohort study of zoonotic influenza transmission. After enrollment, participants were contacted weekly for 24 months to identify acute influenza-like illnesses (ILI). Follow-up sera were collected at 12 and 24 months. A transmission substudy was also conducted among the family contacts of cohort members reporting ILI who were influenza A positive. Samples were assessed using serological or molecular techniques looking for evidence of infection with human and avian influenza viruses. Over 24 months, 438 ILI investigations among 284 cohort members were conducted. One cohort member was hospitalized with a H5N1 highly pathogenic avian influenza (HPAI) virus infection and withdrew from the study. Ninety-seven ILI cases (22.1%) were identified as influenza A virus infections by real-time RT-PCR; none yielded evidence for AIV. During the 2 years of follow-up, 21 participants (3.0%) had detectable antibody titers (≥ 1:10) against the studied AIVs: 1 against an avian-like A/Migratory duck/Hong Kong/MPS180/2003(H4N6), 3 against an avian-like A/Teal/Hong Kong/w312/97(H6N1), 9 (3 of which had detectible antibody titers at both 12- and 24-month follow-up) against an avian-like A/Hong Kong/1073/1999(H9N2), 6 (1 detected at both 12- and 24-month follow-up) against an avian-like A/Duck/Memphis/546/74(H11N9), and 2 against an avian-like A/Duck/Alberta/60/76(H12N5). With the exception of the one hospitalized cohort member with H5N1 infection, no other symptomatic avian influenza infections were detected among the cohort. Serological evidence for subclinical infections was sparse with only one subject showing a 4-fold rise in microneutralization titer over time against AvH12N5. In summary, despite conducting this closely monitored cohort study in a region enzootic for H5N1 HPAI, we were unable to detect subclinical avian influenza infections, suggesting either that these infections are rare or that our assays are insensitive at detecting them

Pairwise comparisons of African and Asian Zika virus strains.^*

<p>*Lightface type = Percent nucleotide divergence; Boldface type = Percent amino acid divergence.</p>†<p>GenBank accession no. AY632535.</p

Zika virus nucleotide and amino acid alignments.

<p>Neighbor-joining phylogeny generated from open reading frame nucleotide sequences of Zika virus strains. The tree was rooted with Spondweni virus (GenBank accession number DQ859064). The scale at the bottom of the tree represents genetic distance in nucleotide substitutions per site. Numbers at the nodes represent percent bootstrap support values based on 1,000 replicates. Isolates are represented according to strain name, country of origin, and year of isolation. The lineage of each virus is indicated to the right of the tree. *Strains sequenced in this study.</p

Probable distribution of Zika virus based on virus isolation and seroprevalence.

<p>*Earliest report, indicates either the first virus isolation or the first report of seroprevalence.</p>†<p>Seroprevalence was either determined by one or more of the following methods: Haemagglution inhibition, neutralization, complement-fixation, IgG and/or IgM ELISA. Of note, it is possible due to antigenic cross-reactivity among flaviviruses that seropostive individuals may have been previously exposed to one or more flaviviruses and not to Zika virus.</p>‡<p>Viral RNA sequenced from four patients (Lanciotti et al. 2008).</p

Zika virus phylogeny.

<p>Nucleotide (top) and amino acid (bottom) sequences of the envelope protein/gene of Zika virus strains showing the deletions in the potential glycosylation sites of the MR 766 (Uganda, 1947) and the IbH 30656 (Nigeria, 1968) strains. Deletions are indicated by dashes. The “N” at position 467 of the P6-740 strain (Malaysia, 1966) represents an equally weighted double population of the nucleotides “C” and “T”. This translates to an “X” at position 165 of the amino acid alignment.</p

Viruses used in this study.

<p>AP61 = <i>Aedes pseudoscutellaris</i> cells, BHK = baby hamster kidney epithelial cells, C6/36 = <i>Aedes albopictus</i> cells, SM = suckling mouse, Vero = African green monkey kidney cells.</p><p>*The sequence of this isolate was determined by epidemic consensus (EC) from the viral RNA of four patients (Lanciotti et al. 2008).</p>†<p>SM-6 V-1 is a strain of Spondweni virus, all other viruses listed within the table are Zika virus strains.</p>‡<p>Sequenced in this study.</p