Unais' web

Coronavirus disease (COVID-19)

Coronavirus disease (COVID-19) is an infectious disease caused by a newly discovered coronavirus.

Most people who fall sick with COVID-19 will experience mild to moderate symptoms and recover without special treatment.

How it spreads

The virus that causes COVID-19 is mainly transmitted through droplets generated when an infected person coughs, sneezes, or exhales. These droplets are too heavy to hang in the air, and quickly fall on floors or surfaces.

You can be infected by breathing in the virus if you are within close proximity of someone who has COVID-19, or by touching a contaminated surface and then your eyes, nose or mouth. 

Symptoms
COVID-19 affects different people in different ways. Most infected people will develop mild to moderate illness and recover without hospitalization.

Most common symptoms:
   • fever
   • dry cough
   • tiredness
Less common symptoms:
   • aches and pains
   • sore throat
   • diarrhoea
   • conjunctivitis
   • headache
   • loss of taste or smell
   • a rash on skin, or discolouration of fingers or toes

Serious symptoms:
   • difficulty breathing or shortness of breath
   • chest pain or pressure
   • loss of speech or movement
Seek immediate medical attention if you have serious symptoms. Always call before visiting your doctor or health facility.
People with mild symptoms who are otherwise healthy should manage their symptoms at home.
On average it takes 5–6 days from when someone is infected with the virus for symptoms to show, however it can take up to 14 days.

Prevention
Protect yourself and others around you by knowing the facts and taking appropriate precautions. Follow advice provided by your local public health agency.

To prevent the spread of COVID-19:
   • Clean your hands often. Use soap and water, or an alcohol-based hand rub.
   • Maintain a safe distance from anyone who is coughing or sneezing.
   • Don’t touch your eyes, nose or mouth.
   • Cover your nose and mouth with your bent elbow or a tissue when you cough or             sneeze.
   • Stay home if you feel unwell.
   • If you have a fever, cough and difficulty breathing, seek medical attention. Call in             advance.
   • Follow the directions of your local health authority.
Avoiding unneeded visits to medical facilities allows healthcare systems to operate more effectively, therefore protecting you and others.

Treatments
To date, there are no specific vaccines or medicines for COVID-19.
Treatments are under investigation, and will be tested through clinical trials.
If you feel sick you should rest, drink plenty of fluid, and eat nutritious food. Stay in a separate room from other family members, and use a dedicated bathroom if possible. Clean and disinfect frequently touched surfaces.
Everyone should keep a healthy lifestyle at home. Maintain a healthy diet, sleep, stay active, and make social contact with loved ones through the phone or internet. Children need extra love and attention from adults during difficult times. Keep to regular routines and schedules as much as possible.
It is normal to feel sad, stressed, or confused during a crisis. Talking to people you trust, such as friends and family, can help. If you feel overwhelmed, talk to a health worker or counsellor.                                                    https://www.google.com/covid19/#safety-tips

What is Ebola?

Ebola virus disease (EVD), Ebola hemorrhagic fever (EHF) or simply Ebola is a disease of humans and other mammals caused by an ebola virus. Signs and symptoms typically start between 2 days and 3 weeks after contracting the virus, with a fever, throat, muscle and headaches. Then, vomiting, diarrhea and rash usually follows, along with decreased function of the liver and kidneys. Around this time, infected people may begin to bleed both within the body and externally.  Death, if it occurs, is typically 6 to 16 days from the start of symptoms and is often due to low blood pressure from fluid loss.

The virus may be acquired upon contact with blood or other body fluids of an infected human or other animal.^[1] Spread through the air has not been documented in the natural environment. Fruit bats are believed to be the normal carrier in nature, able to spread the virus without being affected. Humans become infected by contact with the bats or a living or dead animal that have been infected by bats. Once human infection occurs, the disease may spread between people as well. Male survivors may be able to transmit the disease via semen for nearly two months. To diagnose EVD, other diseases with similar symptoms such as malaria, cholera and other viral hemorrhagic fevers are first excluded. Blood samples are tested for viral antibodies, viral RNA, or the virus itself to confirm the diagnosis.

Outbreak control requires a coordinated series of medical services, along with a certain level of community engagement. The necessary medical services include rapid detection and contact tracing, quick access to appropriate laboratory services, proper management of those who are infected, and proper disposal of the dead through cremation or burial. Prevention includes decreasing the spread of disease from infected animals to humans. This may be done by only handling potentially infected bush meat while wearing proper protective clothing and by thoroughly cooking it before consumption.  It also includes wearing proper protective clothing and washing hands when around a person with the disease. Samples of body fluids and tissues from people with the disease should be handled with special caution.

No specific treatment for the disease is yet available. Efforts to help those who are infected are supportive and include giving either oral rehydration therapy (slightly sweet and salty water to drink) or intravenous fluids. This supportive care improves outcomes. The disease has a high risk of death, killing between 25% and 90% of those infected with the virus (average is 50%). EVD was first identified in an area of Sudan (now part of South Sudan), as well as in Zaire (now the Democratic Republic of the Congo). The disease typically occurs in outbreaks in tropical regions of sub-Saharan Africa. From 1976 (when it was first identified) through 2013, the World Health Organization reported a total of 1,716 cases.  The largest outbreak to date is the ongoing 2014 West African Ebola outbreak, which is currently affecting Guinea, Sierra Leone, and Liberia.  As of 15 October 2014, 8,998 suspected cases resulting in the deaths of 4,493 have been reported. Efforts are under way to develop a vaccine; however, none yet exists.

Signs and symptoms

The time between exposure to the virus and the development of symptoms of the disease is usually 2 to 21 days.  Some have estimated that around 5% of cases may take greater than 21 days to develop.

Symptoms usually begin with a sudden influenza-like stage characterized by feeling tired, fever, and pain in the muscles and joints. The fever is usually greater than 38.3 °C (100.9 °F). This is than often followed by vomiting, diarrhea and abdominal pain.  Shortness of breath and chest pain may occur next along with swelling, headaches and confusion.  In about half of cases, the skin may develop amaculopapular rash (a flat red area covered with small bumps).

The bleeding phase typically begins five to seven days after first symptoms.  All people show some decreased blood clotting.  Bleeding from mucous membranes or from sites of needle punctures is reported in 40–50% of cases. This may result in the vomiting of blood, coughing up of blood or blood in stool. Bleeding into the skin may create petechiae, purpura, ecchymoses, hematomas (especially around needle injection sites). There may alos be bleeding into the whites of the eyes. Heavy bleeding is uncommon and is usually confined to the gastrointestinal tract.

Recovery may begin between 7 and 14 days after the start of symptoms.  While, death, if it occurs, is typically 6 to 16 days from the start of symptoms and is often due to low blood pressure from fluid loss. In general, the development of bleeding often indicates a worse outcome and this blood loss can result in death. People are often in a coma near the end of life. Those who survive often have ongoing muscle and joint pain, liver inflammation, and decreased hearing among other difficulties.

Cause

Ebola virus disease in humans is caused by four of five viruses in the genus Ebolavirus. The four are Bundibugyo virus (BDBV), Sudan virus (SUDV), Taï Forest virus (TAFV), and one called, simply, Ebola virus (EBOV, formerly Zaire Ebola virus). Ebola virus is the only member of the Zaire ebolavirus species and the most dangerous of the known EVD-causing viruses, as well as being responsible for the largest number of outbreaks. The fifth virus, Reston virus (RESTV), is not thought to cause disease in humans, but has caused disease in non-human primates.  These five viruses are closely related to marburg viruses.

Transmission

The spread of Ebola between people occurs only by direct contact with the blood or body fluids of a person after symptoms have developed.^[1] This includes embalming of an infected dead body or by contact with objects contaminated by the virus, particularly needles and syringes. Body fluids that may transmit ebola viruses include saliva, mucus, vomit, feces, sweat, tears, breast milk, urine, and semen. Entry points include the nose, mouth, eyes, or open wounds, cuts and abrasions.  Transmission from other animals to humans occurs only via contact with body fluids of, or consumption of, an infected mammal, such as a fruit bat, or ape. This is also believed to be the method that has led to human outbreaks. The potential for widespread EVD infections in countries with medical systems capable of observing the correct medical isolation procedures is considered low.

An infected individual with mild early stage symptoms may feel well enough to travel without assistance. At that stage however, that person's ability to spread the disease is often limited. As transmission via air is generally ruled out, the possibility of transmission between non-seat-mate airline passengers is unlikely. Because dead bodies are still infectious, traditional burial rituals may spread the disease. Nearly two thirds of the cases of Ebola infections in Guinea during the 2014 outbreak are believed to have been contracted via unprotected (or unsuitably protected) contact with infected corpses during certain Guinean burial rituals. EBOV and SUDV may be able to persist in the semen of survivors for up to seven weeks, which could give rise to infections and disease via sexual intercourse. It is not entirely clear how an outbreak is initially started.

One of the primary reasons for spread is that the health systems function poorly in parts of Africa where the disease mostly occurs. Medical workers who do not wear appropriate protective clothing may contract the disease. Hospital-acquired transmission has occurred in the United States and African countries due to the reuse of needles or lack of body substance isolation. Some healthcare centers caring for people with the disease do not have running water.

Airborne transmission has not been documented during EVD outbreaks. Transmission among rhesus monkeys via breathable 0.8–1.2 μm airborne droplets has been demonstrated in the laboratory.

Reservoir

Bats are considered the most likely natural reservoir of EBOV. Plants, arthropods, and birds have also been considered. In the wild, transmission may occur when infected fruit bats drop partially eaten fruits or fruit pulp, then land mammals such as gorillas and duikers may feed on these fallen fruits. This chain of events forms a possible indirect means of transmission from the natural host species to other animal species, which has led to research into viral shedding in the saliva of fruit bats. Fruit production, animal behavior, and other factors vary at different times and places that may trigger outbreaks among animal populations.

Bats were known to reside in the cotton factory in which the first cases of the 1976 and 1979 outbreaks were observed, and they have also been implicated in Marburg virus infections in 1975 and 1980. Of 24 plant species and 19 vertebrate species experimentally inoculated with EBOV, only bats became infected. The bats displayed no clinical signs and is evidence that these bats are a reservoir species of the virus. In a 2002–2003 survey of 1,030 animals including 679 bats from Gabon and the Republic of the Congo, 13 fruit bats were found to contain EBOV RNA fragments.  As of 2005, three types of fruit bats (Hypsignathus monstrosus, Epomops franqueti, and Myonycteris torquata) have been identified as being in contact with EBOV. They are now suspected to represent the EBOV reservoir hosts. Antibodies against Zaire and Reston viruses have been found in fruit bats in Bangladesh, thus identifying potential virus hosts and signs of the filoviruses in Asia.

Between 1976 and 1998, in 30,000 mammals, birds, reptiles, amphibians and arthropods sampled from outbreak regions, no Ebola virus was detected apart from some genetic traces found in six rodents (Mussetulosus and Praomys) and one shrew (Sylvisorex ollula) collected from the Central African Republic. Traces of EBOV were detected in the carcasses of gorillas and chimpanzees during outbreaks in 2001 and 2003, which later became the source of human infections. However, the high lethality from infection in these species makes them unlikely as a natural reservoir.

 

Virology

They contain single-strand, non-infectious RNA genomes. Ebolavirus genomes are approximately 19 kilobase pairs long and contain seven genes in the order 3'-UTR-NP-VP35-VP40-GP-VP30-VP24-L-5'-UTR. The genomes of the five different ebola viruses (BDBV, EBOV, RESTV, SUDV, and TAFV) differ in sequence and the number and location of gene overlaps. Like all filoviruses, ebola virions are filamentous particles that may appear in the shape of a shepherd's crook or in the shape of a "U" or a "6", and they may be coiled, toroid, or branched. In general, ebola virions are 80 nm in width, but vary somewhat in length. In general, the median particle length of ebola viruses ranges from 974 to 1,086 nm (in contrast to marburgvirions, whose median particle length was measured at 795–828 nm), but particles as long as 14,000 nm have been detected in tissue culture.

Their life cycle begins with virion attachment to specific cell-surface receptors, followed by fusion of the virion envelope with cellular membranes and the concomitant release of the virus nucleocapsid into the cytosol. Ebolavirus' structural glycoprotein (known as GP1,2) is responsible for the virus' ability to bind to and infect targeted cells. The viral RNA polymerase, encoded by the L gene, partially uncoats the nucleocapsid and transcribes the genes into positive-strand mRNAs, which are then translated into structural and nonstructural proteins. The most abundant protein produced is the nucleoprotein, whose concentration in the cell determines when L switches from gene transcription to genome replication. Replication results in full-length, positive-strand antigenomes that are, in turn, transcribed into negative-strand virus progeny genome copy. Newly synthesized structural proteins and genomes self-assemble and accumulate near the inside of the cell membrane. Virions bud off from the cell, gaining their envelopes from the cellular membrane they bud from. The mature progeny particles then infect other cells to repeat the cycle. The Ebola virus genetics are difficult to study due to its virulent nature.

Pathophysiology

Cells lining the inside of blood vessels (endothelial cells), macrophages, monocytes, and liver cells are the main targets of infection. After infection, a secreted glycoprotein, known as small soluble glycoprotein (sGP) or as the Ebola virus glycoprotein (GP), is synthesized. Ebola virus replication overwhelms protein synthesis of infected cells and host immune defenses. The GP forms a trimeric complex, which binds the virus to the endothelial cells. The sGP forms a dimeric protein that interferes with the signaling of neutrophils, a type of white blood cell, which allows the virus to evade the immune system by inhibiting early steps of neutrophil activation. These white blood cells also serve as carriers to transport the virus throughout the entire body to places such as the lymph nodes, liver, lungs, and spleen. The presence of viral particles and cell damage resulting from budding causes the release of chemical signals (TNF-α, IL-6, IL-8, etc.), which are molecular signals for fever and inflammation. The damage to human cells, caused by infection of the endothelial cells, decreases blood vessel integrity. This loss of vascular integrity is furthered with the synthesis of GP, which reduces specific integrins responsible for cell adhesion to the intercellular structure, and damage to the liver, which leads to improper clotting.

Filoviral infection is also known to interfere with proper functioning of the innate immune system. Ebola virus proteins have demonstrated the ability to blunt the human immune system's response to viral infections by interfering with cells' ability to produce and respond to interferon proteins such as interferon-alpha, interferon-beta, and interferon gamma. This interference is accomplished by the VP24 and VP35 ebola virus structural proteins. When cells are infected with ebola virus, receptors located in the cell's cytosol (such as RIG-I and MDA5) or outside of the cytosol (such as Toll-like receptor 3, Toll-like receptor 7, Toll-like receptor 8, and Toll-like receptor 9), recognize infectious molecules associated with the virus. After these receptors are activated, proteins including interferon regulatory factor 3 and interferon regulatory factor 7 start a signaling cascade that leads to the expression of type 1 interferons. Type 1 interferons are then released and bind to neighboring uninfected cells expressing the IFNAR1 and IFNAR2 receptors on their surface.^[52] Once interferon has bound to its receptors on the neighboring uninfected cell, the signaling proteins STAT1 and STAT2 are activated and move to the uninfected cell'snucleus. This triggers the expression of interferon-stimulated genes, which code for proteins that have antiviral properties. Ebola virus' V24 protein prevents the STAT1 signaling protein in the neighboring uninfected cells from entering the cell's nucleus and therefore prevents the creation of these antiviral proteins. A separate ebola virus protein, known as VP35, directly inhibits the production of interferon-beta.

Diagnosis

The travel and work history along with exposure to wildlife are important to consider when the diagnosis of EVD is suspected. The diagnosis is confirmed by isolating the virus, detecting its RNA or proteins, or detecting antibodies against the virus in a person's blood. Isolating the virus by cell culture, detecting the viral RNA by polymerase chain reaction (PCR) and detecting proteins by enzyme-linked immunosorbent assay (ELISA) works best early and in those who have died from the disease. Detecting antibodies against the virus works best late in the disease and in those who recover.

During an outbreak, virus isolation is often not feasible. The most common diagnostic methods are therefore real-time PCR and ELISA detection of proteins, which can be performed in field or mobile hospitals. Filovirions can be seen and identified in cell culture by electron microscopy due to their unique filamentous shapes, but electron microscopy cannot tell the difference between the various filoviruses despite there being some length differences.

Laboratory testing

Changes on laboratory tests as a result of Ebola virus disease include a low platelet count in the blood, an initially decreased white blood cell count followed by an increase in the white blood cell count, elevated levels of the liver enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and abnormalities in clotting often consistent with disseminated intravascular coagulation (DIC) such as a prolonged prothrombin time, partial thromboplastin time, and bleeding time.

Differential diagnosis

Early symptoms of EVD may be similar to those of other diseases common in Africa including malaria and dengue fever . The symptoms are also similar to those of Marburg virus disease and other viral hemorrhagic fevers.

The complete differential diagnosis is long and includes many other infectious diseases such as typhoid fever, shigellosis, rickettsial diseases, cholera, sepsis, borreliosis, EHEC enteritis, leptospirosis, scrub typhus, plague, Q fever, candidiasis, histoplasmosis, trypanosomiasis, visceral leishmaniasis, measles, and viral hepatitis among others. Non-infectious diseases that can be confused with EVD include acute promyelocytic leukemia, hemolytic uremic syndrome, snake envenomation, clotting factor deficiencies/platelet disorders, thrombotic thrombocytopenic purpura, hereditary hemorrhagic telangiectasia, Kawasaki disease, and warfarin poisoning among others.

Prevention

Infection control

The risk of transmission is increased amongst Ebola caregivers. Recommended measures when caring for people infected with Ebola include barrier-isolation, sterilizing equipment and surfaces, and wearing protective clothing including masks, gloves, gowns, and goggles. If a person with Ebola dies, direct contact with the body of the deceased patient should be avoided. The care of those individuals who have become infected with Ebola must be administered while carefully observing a very high-level of barrier-separation from the person infected, along with various certain cleaning and disinfection techniques. Education of those who provide care in these techniques, and the provision of such barrier-separation supplies has been a priority of the Doctors Without Borders organization. Successfully addressing one of the "biggest danger(s) of infection" faced by medical staff requires learning proper suit-up and removal of personal protective equipment. In Sierra Leone, the typical training period for the use of such safety equipment lasts approximately 12 days.

One step recommended by the World Health Organization is the education of the general public of the risk factors for Ebola infection and of the protective measures individuals can take. These include avoiding direct contact with infected people and regular hand washing using soap and water. Bushmeat, an important source of protein in the diet of some Africans, should be handled with appropriate protective clothing and thoroughly cooked before consumption. Some research suggests that an outbreak in the wild animals used for consumption may result in a corresponding human outbreak. Since 2003, such animal outbreaks have been monitored with the aim of predicting and preventing Ebola outbreaks in humans.

Older burial rituals, which might have included making any kind of direct contact with a corpse, require reformulation such that they consistently maintain a proper protective barrier between the corpse and the living. Risk of transmission does not end with a person's death, and thus it is recommended that the bodies of people who have died from Ebola be buried or cremated only with proper care. Social anthropologists may help find alternatives to traditional rules for burials. Airline crews are instructed to follow a certain isolation procedure should anyone exhibit symptoms resembling the Ebola virus disease.

Ebola viruses can be eliminated with heat (heating for 30 to 60 minutes at 60°C or boiling for 5 minutes). To disinfect surfaces, some lipid solvents such as some alcohol-based products, detergents, sodium hypochlorite (bleach) or calcium hypochlorite (bleaching powder), and other suitable disinfectants at appropriate concentrations can be used. As disinfectants.

In laboratories where diagnostic testing is carried out, biosafety level 4-equivalent containment is required, since ebola viruses are World Health Organization Risk Group 4 pathogens. Laboratory researchers must be properly trained in BSL-4 practices and wear proper personal protective equipment.

Quarantine

Quarantine, also known as enforced isolation, is usually effective in decreasing spread. Governments often quarantine areas where the disease is occurring or individuals who may transmit the disease outside of an initial area. In the United States, the law allows quarantine of those infected with ebola viruses. During the 2014 outbreak, Liberia closed schools. On October 16, 2014, some schools were closed in Ohio and Texas as a precaution after one of two nurses who contracted Ebola after caring for Dallas Ebola victim Thomas Eric Duncan, had returned to the Cleveland area and may have been on the same plane as some students, teachers and parents of students from those schools.

Contact tracing

Contact tracing is regarded as important to contain an outbreak. It involves finding everyone who had close contact with infected individuals and watching for signs of illness for 21 days. If any of these contacts comes down with the disease, they should be isolated, tested, and treated. Then repeat the process by tracing the contacts' contacts.

Treatment

Standard support

No ebola virus-specific treatment is currently approved. However, survival is improved by early supportive care with rehydration and symptomatic treatment. Treatment is primarily supportive in nature. These measures may include management of pain, nausea, fever and anxiety, as well as rehydration via the oral or by intravenous route. Blood products such as packed red blood cells, platelets or fresh frozen plasma may also be used. Other regulators of coagulation have also been tried including heparin in an effort to prevent disseminated intravascular coagulation and clotting factors to decrease bleeding. Antimalarial medications and antibiotics are often used before the diagnosis is confirmed, though there is no evidence to suggest such treatment is in any way helpful.

Intensive care

Intensive care is often used in the developed world. This may include maintaining blood volume and electrolytes (salts) balance as well as treating any bacterial infections that may develop. Dialysis may be needed for kidney failure while extracorporeal membrane oxygen at ion may be used for lung dysfunction.

Alternative medicine

The Food and Drug Administration (FDA) advises people to be careful of advertisements making unverified or fraudulent claims of benefits supposedly gained from various anti-Ebola products. The FDA has already sent out at least one letter of warning to a seller of colloidal silver who made unverified claims of Ebola related benefits, supposedly derived from the use of their products.

Prognosis

Ebola virus disease has a high risk of death in those infected which varies between 25 percent and 90 percent of those infected. As of September 2014, the average risk of death among those infected is 50%. The risk of death was 90% in the 2002–2003 Republic of the Congo outbreak.  There are indications based on variations between countries that early and effective treatment of symptoms (e.g., supportive care to prevent dehydration) may reduce the risk of death

If an infected person survives, recovery may be quick and complete. Prolonged cases are often complicated by the occurrence of long-term problems, such as inflammation of the testicles, joint pains, muscle pains, skin peeling, or hair loss. Eye symptoms, such as light sensitivity, excess tearing, iritis, iridocyclitis, choroiditis, and blindness have also been described.

 From Wikipedia