Serotype Distribution of Clinical Streptococcus pneumoniae Isolates before the Introduction of the 13-Valent Pneumococcal Conjugate Vaccine in Cambodia

Childhood vaccination with the 13-valent pneumococcal conjugate vaccine (PCV13) was introduced in Cambodia in January 2015. Baseline data regarding circulating serotypes are scarce. All microbiology laboratories in Cambodia were contacted for identification of stored isolates of Streptococcus pneumoniae from clinical specimens taken before the introduction of PCV13. Available isolates were serotyped using a multiplex polymerase chain reaction method. Among 166 identified isolates available for serotyping from patients with pneumococcal disease, 4% were isolated from upper respiratory samples and 80% were from lower respiratory samples, and 16% were invasive isolates. PCV13 serotypes accounted for 60% (95% confidence interval [CI] 52–67) of all isolates; 56% (95% CI 48–64) of noninvasive and 77% (95% CI 57–89) of invasive isolates. Antibiotic resistance was more common among PCV13 serotypes. This study of clinical S. pneumoniae isolates supports the potential for high reduction in pneumococcal disease burden and may serve as baseline data for future monitoring of S. pneumoniae serotypes circulation after implementation of PCV13 childhood vaccination in Cambodia.

Multiplex PCR analysis of clusters of unexplained viral respiratory tract infection in Cambodia

BACKGROUND

Fevers of unknown origin constitute a substantial disease burden in Southeast Asia. In majority of the cases, the cause of acute febrile illness is not identified.

METHODS

We used MassTag PCR, a multiplex assay platform, to test for the presence of 15 viral respiratory agents from 85 patients with unexplained respiratory illness representing six disease clusters that occurred in Cambodia between 2009 and 2012.

RESULTS

We detected a virus in 37 (44%) of the cases. Human rhinovirus, the virus detected most frequently, was found in both children and adults. The viruses most frequently detected in children and adults, respectively, were respiratory syncytial virus and enterovirus 68. Sequence analysis indicated that two distinct clades of enterovirus 68 were circulating during this time period.

CONCLUSIONS

This is the first report of enterovirus 68 in Cambodia and contributes to the appreciation of this virus as an important respiratory pathogen.

Genetic hemoglobin disorders, infection, and deficiencies of iron and vitamin A determine anemia in young Cambodian children

In Cambodia, many factors may complicate the detection of iron deficiency. In a cross-sectional survey, we assessed the role of genetic hemoglobin (Hb) disorders, iron deficiency, vitamin A deficiency, infections, and other factors on Hb in young Cambodian children. Data on sociodemographic status, morbidity, and growth were collected from children (n = 3124) aged 6 to 59 mo selected from 3 rural provinces and Phnom Penh municipality. Blood samples were collected (n = 2695) for complete blood count, Hb type (by DNA analysis), ferritin, soluble transferrin receptor (sTfR), retinol-binding protein (RBP), C-reactive protein, and α(1)-acid glycoprotein (AGP). Genetic Hb disorders, anemia, and vitamin A deficiency were more common in rural than in urban provinces (P < 0.001): 60.0 vs. 40.0%, 58.2 vs. 32.7%, and 7.4 vs. 3.1%, respectively. Major determinants of Hb were age group, Hb type, ferritin, sTfR, RBP, AGP >1.0 g/L (P < 0.001), and rural setting (P < 0.05). Age group, Hb type, RBP, elevated AGP, and rural setting also influenced ferritin and sTfR (P < 0.02). Multiple factors affected anemia status, including the following: age groups 6-11.99 mo (OR: 6.1; 95% CI: 4.3, 8.7) and 12-23.99 mo (OR: 2.7; 95% CI: 2.1, 3.6); Hb type, notably Hb EE (OR: 18.5; 95% CI: 8.5, 40.4); low ferritin (OR: 3.2; 95% CI: 2.2, 4.7); elevated AGP (OR: 1.4; 95% CI: 1.2,1.7); rural setting (OR: 2.3; 95% CI: 1.7, 3.1); low RBP (OR: 3.6; 95% CI: 2.2, 5.9); and elevated sTfR (OR: 2.1; 95% CI: 1.7, 2.7). In Cambodia, where a high prevalence of genetic Hb disorders exists, ferritin and sTfR are of limited use for assessing the prevalence of iron deficiency. New low-cost methods for detecting genetic Hb disorders are urgently required.

Isolation of Kaeng Khoi virus from dead Chaerephon plicata bats in Cambodia

A virus isolated from dead Chaerephon plicata bats collected near Kampot, Cambodia, was identified as a member of the family Bunyaviridae by electron microscopy. The only bunyavirus previously isolated from Chaerephon species bats in South-East Asia is Kaeng Khoi (KK) virus (genus Orthobunyavirus), detected in Thailand over 30 years earlier and implicated as a public health problem. Using RT-PCR, nucleotide sequences from the M RNA segment of several virus isolates from the Cambodian C. plicata bats were found to be almost identical and to differ from those of the prototype KK virus by only 2.6-3.2 %, despite the temporal and geographic separation of the viruses. These results identify the Cambodian bat viruses as KK virus, extend the known virus geographic range and document the first KK virus isolation in 30 years. These genetic data, together with earlier serologic data, show that KK viruses represent a distinct group within the genus Orthobunyavirus.

Antibodies to Nipah-like virus in bats (Pteropus lylei), Cambodia

Serum specimens from fruit bats were obtained at restaurants in Cambodia. We detected antibodies cross-reactive to Nipah virus by enzyme immunoassay in 11 (11.5%) of 96 Lyle's flying foxes (Pteropus lylei). Our study suggests that viruses closely related to Nipah or Hendra viruses are more widespread in Southeast Asia than previously documented.