Epidemiologic analysis of respiratory viral infections among Singapore military servicemen in 2016.

BACKGROUND: Respiratory illnesses have been identified as a significant factor leading to lost training time and morbidity among Singapore military recruits. A surveillance programme has been put in place to determine etiological agents responsible for febrile, as well as afebrile respiratory illnesses in a military camp. The goal of the study is to better understand the epidemiology of these diseases and identify potential countermeasures to protect military recruits against them. METHODS: From Jan 2016 - Jan 2017, a total of 2647 respiratory cases were enrolled into the surveillance programme. The cases were further stratified into Febrile Respiratory Illness (FRI, with body temperature > 37.5 °C) or Acute Respiratory Illness (ARI, with body temperature < 37.5 °C). Nasal washes were collected and tested by multiplex PCR to detect 26 different pathogens. RESULTS: One thousand ninety five cases (41% of total cases) met the criteria of FRI in which 932 cases (85% of FRI cases) were screened positive for at least one virus. The most common etiological agents for FRI mono-infection cases were Adenovirus E and Rhinovirus. Recruits infected with H3N2 influenza, Influenza B and Adenovirus E viruses were most likely presented as FRI cases. Notably, H3N2 influenza resulted in the greatest rise in body temperature. The remaining 1552 cases (59% of total cases) met the criteria of ARI in which 1198 cases (77% of ARI cases) were screened positive for at least one virus. The most common etiological agent for ARI mono-infection was Rhinovirus. The distribution pattern for dual infections was different for ARI and FRI cases. Maximum number of pathogens detected in a sample was five for both groups. CONCLUSION: Previous studies on respiratory diseases in military focused largely on FRI cases. With the expanded surveillance to ARI cases, this study allows unbiased evaluation of the impact of respiratory disease pathogens among recruits in a military environment. The results show that several pathogens have a much bigger role in causing respiratory diseases in this cohort.

Molecular characterization of low pathogenic avian influenza viruses, isolated from food products imported into Singapore.

We have completed the genetic characterization of all eight gene segments for four low pathogenic avian influenza (LPAI) viruses. The objective of this study was to detect the presence of novel signatures that may serve as early warning indicators of the conversion of LPAI viruses to high pathogenic avian influenza (HPAI) viruses. This study included three H5N2 and one H5N3 viruses that were isolated from live poultry imported into Singapore as part of the national avian influenza virus (AIV) surveillance program. Based on the molecular criterion of the World Organisation for Animal Health (OIE), sequence analysis with the translated amino acid (aa) sequence of the hemagglutinin (HA) gene revealed the absence of multibasic aa at the HA cleavage site, identifying all four virus isolates as LPAI. Detailed phylogenetic tree analyses using the HA and neuraminidase (NA) genes clustered these isolates in the Eurasian H5 lineage, but away from the HPAI H5 subtypes. This analysis further revealed that the internal genes clustered to different avian and swine subtypes, suggesting that the four isolates may possibly share their ancestry with these different influenza subtypes. Our results suggest that the four LPAI isolates in this study contained mainly avian signatures, and the phylogenetic tree for the internal genes further suggests the potential for reassortment with other different circulating avian subtypes. This is the first comprehensive report on the genetic characterization of LPAI H5N2/3 viruses isolated in South-East Asia.

Pre- and post-exposure prophylaxis of experimental Burkholderia pseudomallei infection with doxycycline, amoxicillin/clavulanic acid and co-trimoxazole.

OBJECTIVES: Melioidosis, a potentially fatal disease of humans and animals, is caused by the gram-negative bacterium, Burkholderia pseudomallei. There is no approved vaccine or effective prophylaxis. Given its potential as a bioterrorism agent and a cause of serious laboratory-acquired infection, we studied the efficacy of pre- and post-exposure oral antibiotic prophylaxis in BALB/c mice infected with aerosolized B. pseudomallei through the inhalational route. METHODS: Amoxicillin/clavulanic acid, doxycycline or co-trimoxazole was administered 48 h before infection as pre-exposure prophylaxis, orally, twice daily and continued up to 10 days post-challenge. In the post-exposure prophylaxis regimen, the oral antibiotics were administered twice daily, at 0, 10, 24 and 48 h and continued for 10 days. Survival of all animals was observed until 21 days. RESULTS: All infected control animals developed infection between 24 and 48 h, and died within 5 days. Animals receiving amoxicillin/clavulanic acid as pre-exposure prophylaxis succumbed to the disease at day 7, whereas those in the co-trimoxazole and doxycycline groups had survival rate of 100% and 80%, respectively, at day 21. As post-exposure prophylaxis, all antibiotics were not effective when treatment was initiated 48 h post-challenge. However, animals receiving co-trimoxazole had a 100% survival rate when the antibiotic was started 0, 10 and 24 h post-infection, and amoxicillin/clavulanic acid was the least effective. CONCLUSIONS: Co-trimoxazole appears to be an effective oral antibiotic both as pre- and post-exposure prophylaxis to B. pseudomallei. Data derived from this study have important implications on the management of laboratory accidents or following an intentional release of B. pseudomallei, a potential bioterrorism agent.