A study of the probable transmission routes of MERS-CoV during the first hospital outbreak in the Republic of Korea

Infections caused by the Middle East respiratory syndrome coronavirus (MERS-CoV) are a serious health issue due to their prevalence and associated mortality. However, the transmission routes of the virus remain unclear, and thus, the current recommended control strategies are not evidence based. In this study, we investigated the transmission routes of MERS-CoV during the first nosocomial outbreak in the Republic of Korea in May 2015 using a multi-agent modeling framework. We identified seven hypothesized transmission modes based on the three main transmission routes (long-range airborne, close contact, and fomite). The infection risks for each hypothesis were estimated using the multi-agent modeling framework. Least-squares fitting was conducted to compare the distribution of the predicted infection risk in the various scenarios with that of the reported attack rates and to identify the hypotheses with the best fit. In the scenarios in which the index patient was a super-spreader, our model simulations suggested that MERS-CoV probably spread via the long-range airborne route. However, it is possible that the index patient shed an average viral load comparable to the loads reported in the literature, and that transmission occurred via a combined long-range airborne and close contact route.

Extensive Viable Middle East Respiratory Syndrome (MERS) Coronavirus Contamination in Air and Surrounding Environment in MERS Isolation Wards

BACKGROUND

The largest outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV) outside the Middle East occurred in South Korea in 2015 and resulted in 186 laboratory-confirmed infections, including 36 (19%) deaths. Some hospitals were considered epicenters of infection and voluntarily shut down most of their operations after nearly half of all transmissions occurred in hospital settings. However, the ways that MERS-CoV is transmitted in healthcare settings are not well defined.

METHODS

We explored the possible contribution of contaminated hospital air and surfaces to MERS transmission by collecting air and swabbing environmental surfaces in 2 hospitals treating MERS-CoV patients. The samples were tested by viral culture with reverse transcription polymerase chain reaction (RT-PCR) and immunofluorescence assay (IFA) using MERS-CoV Spike antibody, and electron microscopy (EM).

RESULTS

The presence of MERS-CoV was confirmed by RT-PCR of viral cultures of 4 of 7 air samples from 2 patients' rooms, 1 patient's restroom, and 1 common corridor. In addition, MERS-CoV was detected in 15 of 68 surface swabs by viral cultures. IFA on the cultures of the air and swab samples revealed the presence of MERS-CoV. EM images also revealed intact particles of MERS-CoV in viral cultures of the air and swab samples.

CONCLUSIONS

These data provide experimental evidence for extensive viable MERS-CoV contamination of the air and surrounding materials in MERS outbreak units. Thus, our findings call for epidemiologic investigation of the possible scenarios for contact and airborne transmission, and raise concern regarding the adequacy of current infection control procedures.

Extensive Viable Middle East Respiratory Syndrome (MERS) Coronavirus Contamination in Air and Surrounding Environment in MERS Isolation Wards

Background.  The largest outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV) outside the Middle East occurred in South Korea in 2015 and resulted in 186 laboratory-confirmed infections, including 36 (19%) deaths. Some hospitals were considered epicenters of infection and voluntarily shut down most of their operations after nearly half of all transmissions occurred in hospital settings. However, the ways that MERS-CoV is transmitted in healthcare settings are not well defined.

Methods.  We explored the possible contribution of contaminated hospital air and surfaces to MERS transmission by collecting air and swabbing environmental surfaces in 2 hospitals treating MERS-CoV patients. The samples were tested by viral culture with reverse transcription polymerase chain reaction (RT-PCR) and immunofluorescence assay (IFA) using MERS-CoV Spike antibody, and electron microscopy (EM).

Results.  The presence of MERS-CoV was confirmed by RT-PCR of viral cultures of 4 of 7 air samples from 2 patients' rooms, 1 patient's restroom, and 1 common corridor. In addition, MERS-CoV was detected in 15 of 68 surface swabs by viral cultures. IFA on the cultures of the air and swab samples revealed the presence of MERS-CoV. EM images also revealed intact particles of MERS-CoV in viral cultures of the air and swab samples.

Conclusions.  These data provide experimental evidence for extensive viable MERS-CoV contamination of the air and surrounding materials in MERS outbreak units. Thus, our findings call for epidemiologic investigation of the possible scenarios for contact and airborne transmission, and raise concern regarding the adequacy of current infection control procedures.

A Study on the Contaminant Dispersion from Isolation Ward under Abnormal Operation of Facilities

Due to the recent outbreaks of infectious diseases, such as severe acute respiratory syndrome (SARS), Influenza and Ebola, isolation facilities have played an important role to prevent infectious diseases from spreading at initial stage. An isolation ward is a facility to isolate patients physically and to care them safely. One way to isolate a patient physically is to build a negative pressure isolation facility. However, unexpected failure or misuse of such facility makes it difficult to maintain negative pressure and eventually causes secondary infection, leaking the infectious pathogen to outside of the isolation ward. This study identifies the amount and velocity of leakage air from a patient ward by tracer gas experiment under abnormal operations of an isolation facility. In addition, computational fluid dynamics (CFD) allowed us to observe the outflow mechanism of pollutant. The results show that abnormal operations of a facility spreads pathogens to neighboring areas immediately and timely actions should be prepared against them.

Epidemiologic features of the first MERS outbreak in Korea: focus on Pyeongtaek St. Mary's Hospital

OBJECTIVES:

This study investigated the epidemiologic features of the confirmed cases of Middle East Respiratory Syndrome (MERS) in Pyeongtaek St. Mary’s Hospital, where the outbreak first began, in order to identify lessons relevant for the prevention and control of future outbreaks.

METHODS:

The patients’ clinical symptoms and test results were collected from their medical records. The caregivers of patients were identified by phone calls.

RESULTS:

After patient zero (case #1) was admitted to Pyeongtaek St. Mary’s Hospital (May 15-May 17), an outbreak occurred, with 36 cases between May 18 and June 4, 2015. Six patients died (fatality rate, 16.7%). Twenty-six cases occurred in the first-generation, and 10 in the second-generation. The median incubation period was five days, while the median period from symptom onset to death was 12.5 days. While the total attack rate was 3.9%, the attack rate among inpatients was 7.6%, and the inpatients on the eighth floor, where patient zero was hospitalized, had an 18.6% attack rate. In contrast, caregivers and medical staff showed attack rates of 3.3% and 1.1%, respectively.

CONCLUSIONS:

The attack rates were higher than those of the previous outbreaks in other countries. The outbreak spread beyond Pyeongtaek St. Mary’s Hospital when four of the patients were moved to other hospitals without appropriate quarantine. The best method of preventing future outbreaks is to overcome the vulnerabilities observed in this outbreak, such as ward crowding, patient migration without appropriate data sharing, and the lack of an initial broad quarantine.

Spaceflight and hind limb unloading induce similar changes in electrical impedance characteristics of mouse gastrocnemius muscle

OBJECTIVE

To assess the potential of electrical impedance myography (EIM) to serve as a marker of muscle fiber atrophy and secondarily as an indicator of bone deterioration by assessing the effects of spaceflight or hind limb unloading.

METHODS

In the first experiment, 6 mice were flown aboard the space shuttle (STS-135) for 13 days and 8 earthbound mice served as controls. In the second experiment, 14 mice underwent hind limb unloading (HLU) for 13 days; 13 additional mice served as controls. EIM measurements were made on ex vivo gastrocnemius muscle. Quantitative microscopy and areal bone mineral density (aBMD) measurements of the hindlimb were also performed.

RESULTS

Reductions in the multifrequency phase-slope parameter were observed for both the space flight and HLU cohorts compared to their respective controls. For ground control and spaceflight groups, the values were 24.7±1.3°/MHz and 14.1±1.6°/MHz, respectively (p=0.0013); for control and HLU groups, the values were 23.9±1.6°/MHz and 19.0±1.0°/MHz, respectively (p=0.014). This parameter also correlated with muscle fiber size (ρ=0.65, p=0.011) for spaceflight and hind limb aBMD (ρ=0.65, p=0.0063) for both groups.

CONCLUSIONS

These data support the concept that EIM may serve as a useful tool for assessment of muscle disuse secondary to immobilization or microgravity.

COMPARING THE EFFECTIVENESS OF ONE- AND TWO-STEP CONDITIONAL LOGIT MODELS FOR PREDICTING OUTCOMES IN A SPECULATIVE MARKET

This paper compares two approaches to predicting outcomes in a speculative market, the horse race betting market. In particular, the nature of one-and two-step conditional logit procedures involving a process for exploding the choices et are outlined, their strengths and weaknesses are compared and the irrelative effectiveness is  evaluated by predicting winning probabilities for horse races at a UK racetrack. The models incorporate variables which are widely recognised as having predictive power and which should therefore be effectively discounted in market odds. Despite this handicap, both approaches produce probability estimates which can be used to earn positive returns, but the two-step approach yields substantially higher profits.