Transmission mode associated with coronavirus disease 2019: a review

OBJECTIVE

In late December 2019 in Wuhan (China), Health Commission reported a cluster of pneumonia cases of unknown etiology, subsequently isolated and named Severe Acute Respiratory Syndrome (SARS) Coronavirus 2 (CoV-2). In this review, the main transmission routes and causes of mortality associated with COVID-19 were investigated.

MATERIAL AND METHODS

A review was carried out to recognize relevant research available until 10 April 2020.

RESULTS

The main transmission routes of COVID-19 have been the following: animal to human and human-to-human pathways, namely: respiratory transmission; oro-fecal transmission; air, surface-human transmission. Transmission from asymptomatic persons, healthcare transmission, and interfamily transmission have been well documented.

CONCLUSIONS

SARS-CoV-2 possesses powerful pathogenicity and transmissibility. It is presumed to spread primarily via respiratory droplets and close contact. The most probable transmission pathway is definitely the inter-human one. Asymptomatic patients seem to play a crucial role in spreading the infection. Because of COVID-19 infection pandemic potential, careful surveillance is essential to monitor its future host adaptation, viral evolution, infectivity, transmissibility, and pathogenicity in order to gain an effective vaccine and flock immunity and reduce mortality as soon and as much as it is possible.

A case of imported Middle East Respiratory Syndrome coronavirus infection and public health response, Greece, April 2014

On 18 April 2014, a case of Middle East Respiratory Syndrome coronavirus (MERS-CoV) infection was laboratory confirmed in Athens, Greece in a patient returning from Jeddah, Saudi Arabia. Main symptoms upon initial presentation were protracted fever and diarrhoea, during hospitalisation he developed bilateral pneumonia and his condition worsened. During 14 days prior to onset of illness, he had extensive contact with the healthcare environment in Jeddah. Contact tracing revealed 73 contacts, no secondary cases had occurred by 22 April.

Influenza A/H1N1/2009 outbreak in a neonatal intensive care unit

BACKGROUND

Outbreaks of influenza A/H1N1/2009 in neonatal intensive care units (NICUs) have been reported only rarely. Annual vaccination of all healthcare workers (HCWs) against seasonal influenza is recommended but compliance is low and exposure to infected staff as the source of nosocomial outbreaks has been described.

AIM

To report an outbreak of influenza A/H1N1/2009 in a tertiary level NICU that resulted in considerable morbidity.

METHODS

When the first influenza case was identified, a prospective study was conducted and control measures were implemented to reduce the spread of infection throughout the NICU. Neonates who developed influenza were treated with oseltamivir, and exposed neonates were given prophylaxis with oseltamivir.

FINDINGS

Two infected infants who were immature by gestational age and birth weight developed pneumonitis requiring respiratory support, and a third full-term neonate had a mild uncomplicated illness. No significant adverse effects were noted during antiviral treatment or prophylaxis. The investigation identified infected HCWs as the likely source of the outbreak. There was a very low influenza vaccination rate of 15% among nursing staff.

CONCLUSION

Nosocomial influenza can cause considerable morbidity, especially in high risk neonates, and is readily transmissible in the NICU setting by unvaccinated staff members who contract influenza. To prevent outbreaks, in addition to infection control measures, the implementation of HCW vaccination is very important. Oseltamivir treatment was well-tolerated even among premature infants and appeared to be effective, because neonates with influenza had complete recovery and only one of those who received prophylaxis developed the infection.

KPC-2-producing Klebsiella pneumoniae infections in Greek hospitals are mainly due to a hyperepidemic clone

To verify the presence of Klebsiella pneumoniae carbapenemase-producing (KPC-producing) Klebsiella pneumoniae in Greece, we asked 40 Greek hospitals participating in the Greek System for the Surveillance of Antimicrobial Resistance (GSSAR) to apply a combination of the modified Hodge test plus EDTA synergy test on all K. pneumoniae clinical isolates obtained from February 2008 which displayed reduced susceptibility to carbapenems (MIC of imipenem > or = 1 mg/L). The presence of the blaKPC gene was confirmed by PCR and sequencing. This procedure revealed the presence of KPC-2 in isolates from 173 patients in 18 hospitals during a period of 11 months. Of these, 166 isolates belonged to a single pulsotype a fact consistent with possible epidemic spread, whereas the remaining seven isolates were further classified into four different pulsotypes. BlaKPC-2 gene was found to be transferable by conjugation in the four pulsotypes other than the prevailing one. The emergence of a new carbapenemase gene in Greece, where high resistance rates to carbapenems in K. pneumoniae due to the spread of the VIM type metalloenzyme have been observed, emphasises the urgent need for the implementation of public health measures in the field of infection control and antibiotic consumption. It also underlines the need to supplement surveillance systems based on susceptibility data with the surveillance of resistance mechanisms.

Cytomegalovirus disease in adult marrow transplant recipients receiving ganciclovir prophylaxis: a retrospective study

In a retrospective study, we compared the incidence and risk of mortality associated with CMV disease in adult allogeneic BMT and PBSC recipients who received ganciclovir prophylaxis three-times-per-week (78 patients) vs five-times-per-week (137 patients). Active CMV infection occurred in 28 (41%) and 26 (21%) in the three- vs five-times-per-week groups, respectively (P < 0.005). CMV disease developed in 11 (16%) and five (4%) patients who received ganciclovir prophylaxis in the three-times-per-week vs five-times-per-week groups (P < 0.004). The CMV-attributable mortality rate was 1.5% and 12% in the five- vsthree-times-per-week groups, respectively (P < 0.003). Risk factors for CMV disease, significant at the P < 0.05 level in the multivariate analysis, were ganciclovir prophylaxis at three-times-per-week, receiving a T cell-depleted (TCD) marrow, and tacrolimus as prophylaxis for GVHD. These data suggest that ganciclovir five-times-per-week significantly reduced the incidence and mortality of CMV disease in allogeneic BMT and PBSC recipients. However, ganciclovir five-times-per-week was less effective for the prevention of CMV disease in patients receiving TCD marrow or tacrolimus.