Droplets emitted by talking, coughing or sneezing as well as direct or indirect contact can transmit the disease.
Corona viruses and covid-19
This name has been given to viruses that have protrusions on their surface that resemble a crown.
What types of coronaviruses are there?
Corona viruses were discovered more than 50 years ago. Most are of veterinary interest, as they infect pigs, cats, mice, rats, cows, chickens, turkeys.
Humans are affected by the following strains, causing epidemics of light viruses of the common cold type every year around the world:
- 229E Common cold
- NL63 Common cold with laryngitis
- OC43 Respiratory infection and possibly gastroenteritis
- HKU1 Respiratory infection
229E and OC43 account for 25% of common colds annually, after rhinoviruses. The incubation time is about 2 days and the disease lasts 5-7 days. It is characterized by wheezing, sneezing, mild sore throat, sometimes accompanied by headache and general malaise.
Fever and cough are relatively rare in the common cold .
How is COVID-19 transmitted?
Droplets emitted by talking, coughing or sneezing as well as direct or indirect contact can transmit the disease.
Infections with coronaviruses HCoV 229E, OC43, and NL63 happen worldwide, starting early in childhood and recurring at all ages. These viruses offer no cross protection, meaning if someone gets sick from one coronavirus, they can get sick again from another. Also, the immunity a coronavirus leaves behind is short-lived, so a person can become sick again with the same virus after a few months.
Coronavirus epidemics are unpredictable, unlike influenza. For instance, 229E might cause 1% of respiratory infections one year and 35% the next.
What is the relationship between coronaviruses and multiple sclerosis?
In the past, it has been hypothesized that coronaviruses are related to the pathogenesis of multiple sclerosis, as genetic material of 229E and OC43 was found in brains of people suffering from the disease. Some animal coronaviruses administered to mice caused demyelination (the pathologic lesion in multiple sclerosis).
However, this hypothesis was not confirmed and the fact that genetic material of these viruses was also found in patients who died of non-neurological diseases, makes the association even more uncertain.
SARS type coronaviruses
Sometimes, viruses that previously only affected animals begin infecting humans. Experts often blame the practice in southern China of capturing and selling wild mammals for food, which may have helped a bat SARS-type precursor virus adapt to infect cats, raccoons, dogs, and then humans. The frequent discovery of SARS-type coronaviruses in bats suggests these animals are a natural reservoir for these viruses.
Human infections with the first SARS-CoV in 2002 ranged from asymptomatic to very mild, but the virus soon adapted for easy human-to-human transmission. When humans encounter a new coronavirus, they lack antibodies, leading to small or large-scale outbreaks.
SARS-CoV pandemic in 2003
An infected patient traveled to Hong Kong and stayed in a hotel for one day, during which they infected 15 others. Subsequently, these individuals traveled to Toronto, Singapore, Hanoi, and other cities, spreading the virus across 29 countries, resulting in 8,000 cases. Approximately 21% of these cases required hospital care, and 800 people died.
In response, joint efforts by various countries successfully halted the virus’s human-to-human transmission by July 2003. Additionally, it’s known that people can shed SARS-CoV in their feces, posing a potential transmission route.
Researchers have discovered that SARS-CoV remains infectious on smooth surfaces for longer periods compared to other coronaviruses. The virus has a mortality rate of 9.6%, primarily affecting elderly individuals with underlying health conditions.
MERS-CoV outbreaks. Middle East Respiratory Syndrome in 2012
This virus, originating from bats, may have camels acting as intermediaries and reservoirs. Experts recommend that individuals who interact with camels frequently wash their hands and avoid contact with sick animals. Additionally, they advise thoroughly cooking any food derived from camels.
Outbreaks of this disease have been reported in Saudi Arabia, the United Arab Emirates, and South Korea. The virus, which does not appear to be highly contagious, mainly spreads through close contact, such as interactions between caregivers and patients.
Mild symptoms of MERS
- Fever with chills
- Dry cough
- Rarely runny nose and sore throat
Severe MERS symptoms
- Respiratory failure (requires mechanical ventilation)
MERS Incubation – Transmission – Mortality
Incubation time: 2-14 days.
Appearance of first case of COVID-19
On December 26, 2020, in Wuhan, China, doctors admitted a 41-year-old man exhibiting rapidly worsening symptoms of fever, cough, chest tightness, and weakness.
Subsequently, they learned that the man was employed at a local seafood market in Wuhan. This market was notable for its trade in a wide variety of live wildlife, such as hedgehogs, badgers, snakes, and turtles, in addition to seafood.
Upon examining a lung sample from the patient, the doctors identified genetic material closely resembling the SARS-like bat virus SL-CoVZC45, which is known to infect bats.
Name of the novel coronavirus SARS-CoV and the disease
In February 2020, the International Committee on the Classification of Viruses designated the pathogen causing the current pandemic as SARS-CoV-2.
Following this, the World Health Organization named the disease COVID-19.
This effort in naming was focused on avoiding references to race, animals, nations, individuals, or geographical areas to prevent the stigmatization of any social group. The names selected are not only easy to pronounce but also apt for use in potential future outbreaks of this virus.
Epidemiological characteristics of the novel coronavirus SARS-CoV-2
Barriers to epidemiological research. Alternative methods
Recording the number of cases, including mild ones, is essential for monitoring the epidemiological response to the measures implemented.
However, this task is not always straightforward. In an epidemic, barriers often exist in accessing health services. Laboratories may struggle to handle a large volume of tests, leading to only seriously ill patients being referred for diagnostic tests.
An alternative strategy involves recording suspected cases and randomly sampling this population for testing. By using this approach, it’s possible to estimate the exact number of cases. This method was successfully applied during the 2009 influenza pandemic.
The Basic Reproduction Number R is a key epidemiological indicator. It represents the expected number of people an infected person will infect in an entirely susceptible population.
This number signifies the infectious agent’s potential to cause an outbreak.
An R value greater than 1 indicates an ongoing epidemic, while a value less than 1 suggests the epidemic is nearing its end.
For SARS-CoV-2, the estimated R value ranges between 2-3, meaning one patient typically infects 2 to 3 others.
The mortality rate stands at 3.7%.
Patients needing mechanical respiratory support face a 40-60% mortality rate.
How is it transmitted?
- With droplets emitted by a sufferer when he talks, sneezes or coughs. These droplets continue to float for up to 20 minutes after they are emitted, before settling. These can cause disease if they enter another person’s respiratory system.
- If someone touches a contaminated surface and then touches their nose, mouth or eyes. It is not considered the main mode of transmission, but there is still much we do not know about this particular virus.
- Shortness of breath
- Sore throat
- Decreased taste and smell
- Severe difficulty breathing
- Persistent chest pain or pressure
- Mental confusion or inability to get out of bed
- Cyanosis of the lips or face
How is the reduction of taste and smell explained?
Many COVID-19 patients report experiencing hypoosmia and hypogeusia, which involve reduced senses of smell and taste. French researchers have recognized these as common symptoms of COVID-19, suggesting the virus might attack the nervous system and olfactory mucosa, leading to these symptoms.
Since the virus often doesn’t cause upper respiratory tract symptoms, it might selectively target the olfactory nerve. Experts estimate that around 5% of COVID-19 patients exhibit anosmia and aguesia. However, this percentage could be an underestimate, as patients might not mention these symptoms unless specifically questioned.
In most cases the disease follows a mild course (flu-like) and is treated at home without treatment.
In some patients, severe deterioration of respiratory function is observed after 1 week. These patients should be supported with mechanical ventilation.
What is causing the rapid deterioration after the 1st week ?
It is impressive that the sharp deterioration of the disease occurs when the number of viruses in the respiratory system begins to decrease.
It appears that the deterioration is due to an outbreak of a pathological reaction, called a cytokine storm.
What are cytokines?
They are proteins that are produced by a wide variety of cells and aim to influence the function of other cells. Their mode of action is reminiscent of hormones, but they have many differences.
In the immune system, they are produced by defense cells (T-lymphocytes and macrophages), with the purpose of:
- To “call for help” other immune cells, to rally with them.
- To cause maturation of immature immune cells.
- To initiate and maintain an inflammation.
What is cytokine storm syndrome?
It involves a pathological, stormy production of cytokines, leading to intense diffuse inflammation. This situation strays from its original purpose of combating the pathogenic agent and instead evolves into the destruction of the organ.
Who are considered high risk?
The disease COVID-19 is still very new and the information we have about it is very limited. From our experience to date, we know that people who have:
- Age 65 or living in nursing homes or long-term care facilities
- Chronic lung disease, such as moderate to severe bronchial asthma
- Immunosuppression (chemotherapy, immunodeficiency, transplant, AIDS, corticoid therapy, etc.)
- Severe obesity (BMI>40)
- Chronic kidney failure
- Liver disease
Transmission from mother to fetus
Doctors generally regard the transmission of SARS-CoV-2 from mother to fetus as unlikely. Yet, following birth, there is a risk of others infecting the newborn. To date, only a small number of newborns have tested positive for SARS-CoV-2. However, it remains uncertain whether they contracted the virus before or after birth. Additionally, researchers have not detected the virus in amniotic fluid, breast milk, or other obstetric samples.
Breastfeeding from a mother with COVID-19
Breast milk protects against many diseases and is the best food for the infant. In a limited number of studies SARS-CoV-2 was not detected in breast milk. But further research is still needed to answer this question with certainty.
If you have COVID-19 and decide to breastfeed:
- Wear a mask
- Wash your hands before breastfeeding.
If you decide to express milk with a breast pump:
- You use your own personal pump
- Wash your hands every time before touching the pump and parts
- Carefully follow the instructions for disinfecting the pump and accessories
- Make sure there is someone healthy to administer the milk to the newborn
While no proven treatment for COVID-19 exists yet, doctors are experimenting with various antiviral and antimalarial drugs. Early studies in China suggest chloroquine might reduce fever, improve lung lesions visible in CT scans, and slow the disease’s progression. In France, studies indicate that hydroxychloroquine, particularly with azithromycin, could reduce viral loads in patients.
Coronaviruses, enveloped viruses with single-stranded RNA, belong to the Coronaviridae family. Six types cause human diseases: four usually cause common cold symptoms, while two, SARS-CoV and MERS-CoV, lead to more severe illnesses. In the past two decades, SARS-CoV and MERS-CoV have caused over 10,000 cases, with MERS-CoV having a 34% fatality rate and SARS-CoV 10%.
In December 2019, a novel coronavirus emerged in Wuhan, China, initially causing pneumonia. Scientists later identified this virus as SARS-CoV-2, capable of spreading between humans, even without symptoms, and leading to severe respiratory diseases.
The CDC states that SARS-CoV-2 symptoms can appear 2 to 14 days after exposure, commonly including fever, cough, myalgias, and shortness of breath. Less common symptoms are sore throat, headache, diarrhea, and vomiting, with older men more frequently affected.
For diagnosing SARS-CoV-2, the WHO recommends samples from the lower respiratory tract but suggests using upper respiratory specimens if lower tract collection isn’t possible.