Thursday, March 19, 2020

In phase 2 airports and in phase 3 hospitals are the hot spots for infection?

In phase 2 airports and in phase 3 hospitals are the hot spots for infection?

Dr K K Aggarwal
President CMAAO, HCFI and Past National President IMA

In phase 2 airports are the hotspots

1. As on 19th March UAE has 113 cases only
2. But 15 people who entered Maharashtra from Dubai tested positive
3. They answer not infected in Dubai, aircraft, Indian Immigration. Then where did they get the infection.?? Dubai airport

One of the largest airports

Centrally air conditioned

Transit area for most airlines

Transit time is usually ion hours

Humid atmosphere

A typical cough starts with a deep breath, followed by a compression of air in the lungs and then a crackling burst as that air is forced out in a fraction of a second.

The cough begins with an initial gasp that draws air deep into the lungs. Next, the glottis snaps shut, putting a lid over the trachea, or windpipe. The third step is the forceful contraction of the muscles of the chest cage, abdomen, and diaphragm. In normal breathing, these muscles push air gently from the lungs up through the nose and mouth. But when the glottis is closed, the air can't move out, so tremendous pressure builds up in the air passages. Finally, the glottis swings open and the air rushes out. And it is quite a rush; in a vigorous cough, the air travels out at nearly the speed of sound, creating the barking or whooping noise that we call a cough. [Harvard health]

A cough can be a conscious, voluntary act or an uncontrollable, involuntary reflex. In the latter case, stimulation of nerves in the larynx ("voice box") and respiratory tract initiates the entire process. These nerves can be irritated by infections, allergies, cold air, tumours, chemical agents such as smoke, mechanical factors such as dust particles, or by normal body fluids such as nasal mucus or stomach acid. It's no wonder, then, that so many different things can trigger a cough.

The average human cough would fill about three-quarters of a two-litter soda bottle with air — air that shoots out of the lungs in a jet several feet long. Coughs also force out thousands of tiny droplets of saliva. About 3,000 droplets are expelled in a single cough, and some of them fly out of the mouth at speeds of up to 50 miles per hour. [, American Institute of Physics.]

Sneeze: It starts at the back of the throat and produces even more droplets — as many as 40,000 to 100,000— some of which rocket out at speeds greater than 100-200 miles per hour. The vast majority of the droplets are less than 100 microns across — the width of a human hair. Many of them are so tiny that they cannot be seen with the naked eye.

If a person is sick, the droplets in a single cough may contain as many as two hundred million individual virus particles. The number varies dramatically and changes over the course of an infection as the immune system clears out the virus. Generally, a sick person is most infectious as soon as the first symptoms appear and less infectious as his or her immune system clears the virus.

Airports and airplanes are notoriously germy given the high traffic and turnover. (Coronavirus “super spreader” businessman Steve Walsh likely contracted the virus at a conference in Singapore, then flew to France and travelled to Geneva, Switzerland, and finally flew England’s Gatwick Airport, for example.) Self‐service check‐in screens, gate bench armrests, water fountain buttons, door handles at airports, seats, tray tables and handles of lavatories in aircraft, tend to be bacteria hotspots. So, it’s extra important to wash your hands after touching these areas.
Researchers used epidemiological modelling to simulate how handwashing could impact the “diffusion of infections worldwide.” They calculated that if 60% of travellers had clean hands, it has the potential to slow a global disease by 69%. But even if just 30% of travellers kept their hands clean, it could reduce the impact of a disease by 24%.
Researchers also determined the airports that theoretically could have the most impact in spreading a virus, because they provide direct connections to “mega-hub airports,” offer in- and out-bound international flights and are located at “geographically conjunctive points.”

With those metrics, the airports that they deemed would have the “greatest impact” are London’s Heathrow, Los Angeles International Airport, John F. Kennedy International Airport in New York, Sydney Airport and Paris-Charles De Gaulle Airport. [Christos Nicolaides, study author and postdoctoral fellow at the MIT Sloan School of Management]
My opinion is Dubai airport will fit into the same. 

In phase 3 hospitals will be the hotspots
The evidence: NEJM Marc 18:  

1. “If protecting patients is difficult, so is protecting health care workers, including nurses, respiratory therapists, and those tasked to clean the rooms between patients. When we spoke, Dr. D. was one of six physicians in his division to have suspected Covid-19 infection. Given testing lags and the proportion of infected people who remain asymptomatic, it’s too soon to know the rate of infection among caregivers. And it is precisely these circumstances that make infection control so difficult. “The infection is everywhere in the hospital,” Dr. D. told me. “Although you wear protective gear and do the best you can, you cannot control it.”

2. The irony is that despite health workers’ being “the glue that holds the health system and outbreak response together,” per Tedros Ghebreyesus, director-general of the WHO, 41% of the Covid-19 cases in Wuhan resulted from hospital-related transmission.  Health care providers are at increased risk for developing the condition and spreading it. Work stress is believed to weaken their immune systems, and close, intimate care of patients can lead to exposure to a higher viral load. Despite performing selfless work on behalf of their communities, health care workers have faced social stigma during this outbreak. [Wu Z, McGoogan JM. Characteristics of and important lessons from the coronavirus disease 2019 (COVID-19) outbreak in China: summary of a report of 72 314 cases from the Chinese Center for Disease Control and Prevention. JAMA 2020 February 24; Chang D, Xu H, Rebaza A, Sharma L, Dela Cruz CS. Protecting health-care workers from subclinical coronavirus infection. Lancet Respir Med 2020;8(3): e13-e13.]

3. “We found that the stability of SARS-CoV-2 was similar to that of SARS-CoV-1 under the experimental circumstances tested. This indicates that differences in the epidemiologic characteristics of these viruses probably arise from other factors, including high viral loads in the upper respiratory tract and the potential for persons infected with SARS-CoV-2 to shed and transmit the virus while asymptomatic.3,4 Our results indicate that aerosol and fomite transmission of SARS-CoV-2 is plausible, since the virus can remain viable and infectious in aerosols for hours and on surfaces up to days (depending on the inoculum shed). These findings echo those with SARS-CoV-1, in which these forms of transmission were associated with nosocomial spread and super-spreading events,5 and they provide information for pandemic mitigation efforts.”

No comments:

Post a Comment