Identification of Leptospira Species in Environmental Soil of Urban Settlements in Cambodia.

Background: Leptospirosis represents a major public health threat in Cambodia. To help establish preventive strategies for leptospirosis, we isolated and identified Leptospira from soil collected in Phnom Penh and its neighboring province during the dry and rainy seasons. Materials and Methods: Soil samples were collected from 15 sites in the Phnom Penh metropolitan area and Kandal Province in 2019 and 2020. A total of 120 soil samples were collected and analyzed after culturing. Cultured isolates were identified at the species level using 16S rRNA and gyrB gene sequencing analysis. Results: The positive culture rate for Leptospira was significantly higher for samples collected during the rainy season (31 out of 60 samples, 51.7%) than during the dry season (19 out of 60 samples; p < 0.05, chi-squared test). In terms of sampling area, 10 (35.7%) and 13 (46.9%) soil samples from Phnom Penh and 9 (28.1%) and 18 (56.3%) soil samples from Kandal Province were culture-positive when collected during the dry and rainy seasons, respectively. Three isolates from the Kandal samples collected during the dry season were categorized as pathogenic clade type P1 according to 16S rRNA and gyrB sequence analyses. In addition, samples collected during the rainy season from Phnom Penh and Kandal Province (three each) were categorized as clade type P1. The samples with isolates in clade type P1 were collected from riverbanks during both the dry and rainy seasons and from a hospital garden during the rainy season. Conclusions: This is the first report on the isolation of clade P1 Leptospira species in environmental soil samples from Cambodia. Environmental soil appears to be a reservoir for Leptospira in the capital city and surrounding areas of Cambodia. This study contributes to the understanding of Leptospira species distribution in Asian countries.

Pediatric hospitalizations attributable to rotavirus gastroenteritis among Cambodian children: Seven years of active surveillance, 2010-2016.

BACKGROUND: Each year, approximately 1,066 Cambodian children under five years old die of diarrhea, and 51% of these deaths are due to rotavirus gastroenteritis. Quantifying childhood hospitalizations caused by severe rotavirus infections is also important in demonstrating disease burden caused by this virus. The objective of this study is to update and confirm the current burden of pediatric hospitalizations attributable to rotavirus gastroenteritis among Cambodian children using seven years of continuous active, prospective surveillance from 2010 to 2016. We also characterize the circulating rotavirus genotypic strains during this period. METHODS: Active surveillance for rotavirus gastroenteritis was conducted from January 2010 through December 2016 at a national hospital in Phnom Penh, Cambodia. Children <60 months of age who were hospitalized for acute gastroenteritis (AGE) were consented and enrolled. Information on gender, age, clinical characteristics, and month of onset were collected. Stool specimens were collected and tested by enzyme immunoassay for the presence of rotavirus antigen, and genotyping was performed on rotavirus test-positive specimens to characterize predominant rotavirus strains during the surveillance period. RESULTS: Of 7007 children enrolled with AGE and having specimens collected, 3473 (50%) were attributed to rotavirus gastroenteritis. The majority of rotavirus hospitalizations occurred in children younger than two years old (92%). Year-round rotavirus transmission was observed, with seasonal peaks during the cooler, dry months between November and May. Genotypic trends in rotavirus were observed over the surveillance period; the predominant rotavirus strains changed from G1P[8] (2010-2012), to G2P[4] (2013-2014), the emergence of genotype G8P[8] in 2015, and G3P[8] in 2016. CONCLUSIONS: Rotavirus is the leading cause of severe acute gastroenteritis hospitalizations in Cambodian children under five years old, with 50% of such hospitalizations attributable to rotavirus. Over 90% of rotavirus hospitalizations occurred in children under 2 years of age. Changes in the predominant rotavirus strains occurred over time among these unvaccinated children. This information is important to understand and prioritize the current potential impacts upon child health that could be achieved through the introduction of rotavirus vaccines in Cambodia.

Molecular Epidemiological Survey of Leptospira Infection of Wild Rodents in the Urban Settlement of Cambodia.

INTRODUCTION: Leptospirosis remains a major public health threat in Cambodia. In this study, we aimed at facilitating the development of preventive strategies against leptospirosis in Cambodia by conducting molecular epidemiological surveys of Leptospira infection among wild rodents. MATERIALS AND METHODS: One hundred sixty-three wild rodents were captured in the capital Phnom Penh and surrounding areas, and their kidneys and bladders were collected for analysis. Identification of wild rodent species was determined by using the cytochrome c oxidase I gene. TaqMan PCR of the flagellin B gene (flaB) was performed to detect Leptospira, and species of the isolates were identified by flaB sequencing analysis. RESULTS: The species and respective number of rodents collected were as follows: Rattus norvegicus, 80 (49.1%); Rattus argentiventer, 53 (32.5%); Rattus exulans, 6 (3.7%); Rattus indica, 15 (9.2%); Maxomys surifer, 3 (1.8%); and Rattus sp., 6 (3.7%). Leptospira was detected in 20 out of the 163 rodents (12.3%) and was categorized as either Leptospira interrogans or Leptospira noguchii. R. norvegicus had the highest prevalence of Leptospira (17.5%), and R. argentiventer and Rattus sp. showed infection rates of 9.4% and 16.7%, respectively. CONCLUSIONS: Based on these results, wild rodents living in urban areas of Cambodia were found to be important reservoirs of highly virulent Leptospira. The flaB sequence results of our study provided information regarding the prevalence of Leptospira species, which was dependent on the rodent species. This study is the first study on leptospirosis in wild rodents in the urban areas of Cambodia, where there is limited information on leptospirosis.

Hospital-based surveillance for rotavirus diarrhoea in Phnom Penh, Cambodia, March 2005 through February 2007.

Globally rotavirus is the most common cause of severe gastroenteritis in children. From March 2005 through February 2007, a prospective hospital-based surveillance study was conducted at a national hospital in Phnom Penh, Cambodia, to estimate the burden of rotavirus hospitalizations among children aged <5 years old and to determine strain patterns. Children with diarrhoea underwent standard clinical evaluations. Parents were interviewed for demographic and family information. Faecal specimens were tested for rotavirus by enzyme immunoassay (EIA) and positive specimens were further characterized. Of 2817 hospitalized children with diarrhoea, 56% (n=1278) were positive for rotavirus antigen. The G1P[8] strain was the most common genotype (53%) followed by G2P[4] (10%). The findings suggest a need for improved prevention and control programs for rotavirus diarrhoea in Cambodia.