Droplets emitted by talking, coughing or sneezing as well as direct or indirect contact can transmit the disease.
Corona viruses
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 are coronaviruses transmitted?
Droplets emitted by talking, coughing or sneezing as well as direct or indirect contact can transmit the disease.
Epidemiological data.
Infections with HCoV 229E, OC43 and NL63 occur worldwide. They begin very early in childhood and recur at all ages.
There is no cross protection. That is, if someone gets sick from one coronavirus, they can then get sick from someone else. Also, the immunity left by a coronavirus has a short duration. This means that he can get sick again from the same virus after a few months.
Epidemics of coronaviruses, unlike those of influenza, are not predictable. For example 229E may account for 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
It happens from time to time, that a virus that until then only affected animals, passes to humans and begins to cause human infection.
The habit of population groups in southern China to capture wild mammals and sell them alive for consumption in restaurants has been blamed. It is speculated that these tactics adapted the bat SARS-type precursor virus to be able to infect cats, raccoons, dogs and then humans. The isolation of many SARS-type coronaviruses in bats creates the hypothesis that these animals function as a natural reservoir of such viruses.
The first SARS-CoV infections of humans in 2002 ranged from asymptomatic to very mild. Soon the virus adapted to be easily transmitted from person to person.
Whenever humans are first confronted with a new coronavirus, they have not developed antibodies, resulting in outbreaks of small or large scale.
SARS-CoV pandemic in 2003
An infected patient traveled to Hong Kong, where he stayed in a hotel for one day. 15 patients were infected who then traveled to Toronto, Singapore, Hanoi and other cities, spreading the virus to 29 countries with 8,000 cases. 21% required hospital support and 800 died.
Coordinated actions by all states resulted in the cessation of human-to-human transmission of the virus in July 2003.
SARS-CoV is also shed in feces, through which transmission can occur.
SARS-CoV has been found to retain its infectivity on smooth surfaces for a longer time than other coronaviruses.
Mortality: 9.6% (mainly elderly people with underlying diseases).
MERS-CoV outbreaks. Middle East Respiratory Syndrome in 2012
And this virus comes from bats. Camels play an unclear intermediary role here and are thought to act as a reservoir of the virus.
People who come into contact with camels are advised to wash their hands frequently and not to touch sick animals. Foods that come from a camel must be cooked well.
The disease has caused outbreaks in Saudi Arabia, the United Arab Emirates and South Korea.
It doesn’t seem to be very contagious. It is mainly transmitted by close contact, such as that of the caregivers of the sufferers.
Mild symptoms of MERS
- Fever with chills
- Headaches
- Dry cough
- Diarrhea
- Rarely runny nose and sore throat
Severe MERS symptoms
- Tachypnea
- Respiratory failure (requires mechanical ventilation)
MERS Incubation – Transmission – Mortality
Incubation time: 2-14 days.
Mortality: 35%.
Novel coronavirus SARS-CoV
Appearance of first case
China, Wuhan city. December 26, 2020. A 41-year-old man was admitted with fever, cough, chest tightness, and weakness. His condition was rapidly deteriorating.
It was found that the man worked at a local seafood market, where apart from seafood, a wide variety of live wildlife such as hedgehogs, badgers, snakes and turtles were traded.
In a sample taken from the patient’s lungs, genetic material was found that was very similar to a SARS-like virus that infects bats, bat virus SL-CoVZC45.
Name of the novel coronavirus SARS-CoV and the disease
In February 2020, the International Committee on the Classification of Viruses gave the pathogenic cause of the current pandemic the name SARS- CoV-2 .
The World Health Organization gave the disease the name of COVID-19 .
An effort was made to give a name that would not refer to race, animal, nation, person, geographical area, would not stigmatize a social group, would be easily pronounced and could be used in future outbreaks of this virus.
Epidemiological characteristics of the novel coronavirus SARS-CoV-2
A basic epidemiological indicator is the Basic Reproduction Number R 0 . It is the expected number of people who will be infected by an infected person, in a population that is all susceptible.
This number indicates how likely the infectious agent is to cause an outbreak.
R 0 >1 means that the epidemic is ongoing, while R 0 <1 means that the epidemic is coming to an end.
For SARS-CoV-2 R 0 is estimated between 2-3. That is, one patient infects 2 to 3 others.
Mortality: 3.7%.
Those requiring mechanical respiratory support have a 40-60% mortality rate.
Barriers to epidemiological research. Alternative methods
Recording the number of cases, including mild cases, is necessary to monitor the epidemiological response of the measures taken.
But this is not always easy. In an epidemic there are often barriers to access to health services. Laboratories cannot handle a large number of tests and often only seriously ill patients are referred for diagnostic tests.
An alternative approach is to record suspected cases and randomly sample for testing this population. By reduction the exact number of cases can be calculated. The method was successfully applied during the 2009 influenza pandemic.
Diagnosis.
“Reading” a positive test is complicated by the fact that the molecular test detects viral RNA without being able to distinguish whether it is inside intact (and therefore infectious) copies of the virus or free.
In many infectious diseases such as SARS-CoV, MERS, Ebola, Zika, etc. it is proven that the RNA of the virus is detected long after the disappearance of infectious viruses. In the case of the measles virus RNA of the virus is detected up to 8 weeks after the viruses are completely destroyed.
Free genetic material theoretically cannot cause infection, but there is insufficient research data to rule it out.
Detection of intact viruses in the laboratory is done only with cell cultures. But these, in addition to being slow, also have very low sensitivity and specificity.
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.
General symptoms
- Fever
- Cough
- Shortness of breath
- Shudder
- Headaches
- Headache
- Sore throat
- Decreased taste and smell
Serious symptoms:
- 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?
One of the symptoms of the disease that many patients present is hypoosmia and hypogeusia (reduced sense of smell and taste). French researchers found that this is a common symptom that characterizes the disease COVID-19.
The ability of the virus to attack the nervous system as well as the olfactory mucosa are possible mechanisms for the appearance of the symptom.
However, the fact that the virus usually does not cause symptoms from the upper respiratory tract, raises the suspicion that the virus selectively attacks the olfactory nerve itself.
The incidence of anosmia and aguesia in patients with COVID-19 has been estimated to be 5%. But perhaps this percentage is underestimated, as these symptoms are probably not reported spontaneously by the sufferer, if they are not asked the appropriate questions.
Clinical course
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 is a pathological stormy production of cytokines, resulting in intense diffuse inflammation. The situation deviates from its original goal, which was to fight the pathogenic agent, and evolves into 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)
- Diabetes
- Chronic kidney failure
- Liver disease
Transmission from mother to fetus
It is not considered likely. After birth, however, the child can be infected by another person. To date only a very small number of newborns have tested positive for SARS-CoV-2, but it is unknown whether these newborns acquired the virus before or after birth.
The virus has not been detected 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
Treatment
There is no proven treatment for COVID-19.
Various anti-viral drugs have been tried, as well as anti-malarial drugs.
Early studies conducted in China showed that chloroquine may be associated with a reduction in fever, improvement in pulmonary lesions on CT scans, and slowing of disease progression. Two French studies showed that hydroxychloroquine could reduce the viral load in patients with the disease, especially in combination with the antibiotic azithromycin.
Coronaviruses (or coronaviruses) are enveloped viruses containing non-segmented single-stranded positive polarity RNA and belonging to the Coronaviridae family. There are six types of coronaviruses known to cause disease in humans. Four species (229E, OC43, NL63 and HKU1) cause the symptoms of the common cold while the other two (SARS-CoV* [Severe Acute Respiratory Syndrome Coronavirus] & MERS-CoV** (Middle East Respiratory Syndrome Coronavirus]) cause more serious conditions SARS-CoV and MERS-CoV have caused a combined total of more than 10,000 cases over the past two decades, with a case fatality rate of 34% for MERS-CoV and 10% for SARS-CoV.
In December 2019, some people living or working around the Huanan Seafood Market in Wuhan, Hubei Province, China, developed pneumonia of unknown etiology. Molecular analysis of samples from these patients pointed to a novel coronavirus as the cause, which was first named 2019 Novel Coronavirus (2019-nCoV) and then SARS-CoV-2.
Human-to-human transmission of SARS-CoV-2 has been confirmed, even during the asymptomatic incubation period, and the virus can cause severe respiratory diseases like those caused by SARS-CoV. Although pneumonia is the main disease, a few patients develop severe pneumonia, pulmonary edema, acute respiratory distress syndrome or multiple organ failure, and death.
The US Centers for Disease Control and Prevention (CDC) believes that symptoms of SARS-
CoV-2 can appear from 2 days to 14 days after exposure, with fever, cough, myalgias and shortness of breath being the most common symptoms. Less common symptoms are sore throat, headache, diarrhea and vomiting. Older men seem to be more affected.
The WHO recommends for the diagnosis of SARS-CoV-2 disease samples from the lower respiratory tract (sputum, endotracheal suction or bronchoalveolar lavage). However, if collection is not possible, upper respiratory tract specimens such as nasopharyngeal lavage or nasopharyngeal along with oropharyngeal swab should be used.
