Classic Clock

Selasa, 13 Mei 2014

BELAJAR TENTANG VIRUS CORONA MERS PADA MANUSIA (HUMAN CORONAVIRUSES)


Berikut merupakan kutipan ilmiah kedokteran tentang virology corona yang sangat bermanfaat bagi Penulis sehingga disusun dan digunakan sebagai referensi pribadi.



MERS

A second patient in the U.S. has been identified as having the potentially deadly virus known as MERS (Middle East respiratory syndrome), the CDC announced today.
The patient, like the first one identified earlier this month, is also ahealth care worker who lives and works in Saudi Arabia. The patient was visiting family in the U.S. He is now in good condition in an Orlando-area hospital. "The patient is isolated and doing well," Tom Frieden, MD, director of the CDC, said at a news conference.
CDC and Florida public health officials declined to identify the new patient or to provide the patient's gender. The patient traveled by plane from Jeddah, Saudi Arabia, to London May 1, then on to Boston, Atlanta, and Orlando.
The patient went to the emergency room on May 8. The CDC confirmed the MERS tests results on Sunday evening.
Over the next few days, public health officials will notify roughly 500 passengers who were on the U.S. legs of the flights, alerting them to be aware of possible symptoms and to seek medical help if they notice any.
The general public is at low risk for contracting the virus, said Anne Schuchat, MD, director of the National Center for Immunization and Respiratory Diseases. She also spoke at the news conference. "The virus has not shown the ability to spread from person to person in a community setting. It has been really universally [found] in people who have had very close contact."
The first U.S. case, a patient visiting Indiana, was confirmed last week. The first patient has recovered and was released from an Indiana hospital May 9. No one in contact with that patient has come down with any MERS symptoms.

Increase in MERS Cases

MERS was first identified in Saudi Arabia in 2012. Symptoms include fevercough, and shortness of breath. There is no vaccine and no known cure.
The MERS virus is related to the SARS (severe acute respiratory syndrome) virus that infected more than 8,000 people worldwide in 2003, killing 774.
To date, 538 laboratory-confirmed cases of MERS have been identified worldwide, with 145 deaths, Schuchat said. Most of those cases, 450, have happened in Saudi Arabia, she said.
"Since March, there has been an increase in cases," she said. Public health officials are trying to determine why.
Worldwide, she said, about one-fifth of the MERS cases have occurred in health care workers.
After you're exposed to the virus, symptoms appear about 5 days later, Schuchat said, ''with an outer limit of 14." So most of those passengers on the same May 1 flights as the Orlando patient would be expected to have developed symptoms by now, she said.
The CDC does not suggest people change travel plans. It does advise that travelers going to countries with MERS closely watch their health and practice good hygiene. Wash your hands often and avoid people who are obviously ill.


About Coronavirus

Q:What are coronaviruses?

A: Coronaviruses are common viruses that most people get some time in their life. Human coronaviruses usually cause mild to moderate upper-respiratory tract illnesses.
Coronaviruses are named for the crown-like spikes on their surface. There are three main sub-groupings of coronaviruses, known as alpha, beta and gamma, and a fourth provisionally-assigned new group called delta coronaviruses.
Human coronaviruses were first identified in the mid 1960s. The five coronaviruses that can infect people are: alpha coronaviruses 229E and NL63 and beta coronaviruses OC43, HKU1, and SARS-CoV, the coronavirus that causes severe acute respiratory syndrome.
Coronaviruses may also infect animals. Most of these coronaviruses usually infect only one animal species or, at most, a small number of closely related species. However, SARS-CoV can infect people and animals, including monkeys, Himalayan palm civets, raccoon dogs, cats, dogs, and rodents.

Q: How common are human coronavirus infections?

A: People around the world commonly get infected with human coronaviruses. However, one exception is SARS-CoV. Since 2004, there have not been any known cases of SARS-CoV infection reported anywhere in the world.

Q: Who can get infected?

A: Most people will get infected with human coronaviruses in their life time. Young children are most likely to get infected. However, you can have multiple infections in your life time. 

Q: How do I get infected?

A: The ways that human coronaviruses spread have not been studied very much, except for SARS. However, it is likely that human coronaviruses spread from an infected person to others through—
  • the air by coughing and sneezing, and 
  • close personal contact, such as touching or shaking hands.
These viruses may also spread by touching contaminated objects or surfaces then touching your mouth, nose, or eyes.
In one case, the SARS virus was though to spread through infected stool that got into the air; people breathed this in and got infected.

Q: When can I get infected?

A: In the United States, people usually get infected with human coronaviruses in the fall and winter. However, you can get infected at any time of the year. 

Q: What are the symptoms?

A: Human coronaviruses usually cause mild to moderate upper-respiratory tract illnesses of short duration. Symptoms may include runny nose, cough, sore throat, and fever. These viruses can sometimes cause lower-respiratory tract illnesses, such as pneumonia. This is more common in people with cardiopulmonary disease or compromised immune systems, or the elderly.
SARS-CoV can cause severe illness. To learn more, see Symptoms of SARS.

Q: How can I protect myself?

A: There are currently no vaccines available to protect you against human coronavirus infection.  You may be able to reduce your risk of infection by—
  • washing your hands often with soap and water,
  • not touching your eyes, nose, or mouth, and
  • avoiding close contact with people who are sick.
For information about hand washing, see CDC’s Clean Hands Save Lives!

Q: What should I do if I get sick?

A: If you have an illness caused by human coronaviruses, you can help protect others by—
  • staying home while you are sick, 
  • avoiding close contact with others,
  • covering your mouth and nose when you cough or sneeze, and
  • keeping objects and surfaces clean and disinfected.

Q: How do I get diagnosed?

A: Laboratory tests can be done to confirm whether your illness may be caused by human coronaviruses. However, these tests are not used very often because people usually have mild illness. Also, testing may be limited to a few specialized laboratories.
Specific laboratory tests may include:
  • virus isolation in cell culture,
  • polymerase chain reaction (PCR) assays that are more practical and available commercially, and   
  • serological testing for antibodies to human coronaviruses.
Nose and throat swabs are the best specimens for detecting common human coronaviruses. Serological testing requires collection of blood specimens.

Q: Are there treatments?

A: There are no specific treatments for illnesses caused by human coronaviruses.
Most people with coronavirus illness will recover on their own. However, some things can be done to relieve your symptoms, such as—
  • taking pain and fever medications (Caution: Aspirin should not be given to children), and
  • using a room humidifier or taking a hot shower to help ease a sore throat and cough.
If you are sick, you should —
  • drink plenty of liquids, and
  • stay home and rest.
If you are concerned about your symptoms, you should see you healthcare provider.
Human coronaviruses (HCoVs) 229E, OC43, NL63, and HKU1, are associated most frequently with the common cold, an upper respiratory tract infection characterized by rhinorrhea, nasal congestion, sore throat, sneezing, and cough that may be associated with fever. Symptoms are self-limiting and typically peak on day 3 or 4 of illness. HCoV infections also may be associated with acute otitis media or asthma exacerbations. Less frequently, HCoVs have been associated with lower respiratory tract infections, including bronchiolitis, croup (especially HCoV-NL63), and pneumonia, primarily in infants and immunocompromised children and adults.
SARS-CoV, the HCoV responsible for the 2002–2003 global outbreaks of severe acute respiratory syndrome (SARS), is associated with more severe symptoms. It disproportionately affects adults, who typically present with fever, myalgia, headache, malaise, and chills followed by a nonproductive cough and dyspnea generally 5 to 7 days later. Approximately 25% of infected adults develop watery diarrhea. Twenty percent develop worsening respiratory distress requiring intubation and ventilation. The overall associated mortality rate is approximately 10%, with most deaths occurring in the third week of illness. The case fatality rate in people older than 60 years of age approaches 50%. Typical laboratory abnormalities include lymphopenia and increased lactate dehydrogenase and creatinine kinase concentrations. Most have progressive unilateral or bilateral ill-defined airspace infiltrates on chest imaging. Pneumothoraces and other signs of barotrauma are common in critically ill patients receiving mechanical ventilation.
SARS-CoV infections in children are less severe than adults; notably, no infants or children died from SARS-CoV infection in the 2002–2003 outbreaks. Infants and children younger than 12 years of age who develop SARS typically present with fever, cough, and rhinorrhea. Associated lymphopenia is less severe, and radiographic changes are milder and generally resolve more quickly than in adolescents and adults. Adolescents who develop SARS have clinical courses more closely resembling those of adult disease, presenting with fever, myalgia, headache, and chills. They also are more likely to develop dyspnea, hypoxemia, and worsening chest radiographic findings. Laboratory abnormalities are comparable to those in adult disease.

ETIOLOGY (See Images)

Coronaviruses are enveloped, nonsegmented, single-stranded, positive-sense RNA viruses named after their corona- or crown-like surface projections observed on electron microscopy that correspond to large surface spike proteins. Coronaviruses are classified in the Nidovirus family. Coronaviruses are host specific and can infect humans as well as a variety of different animals causing diverse clinical syndromes. Three serologically and genetically distinct groups of coronaviruses have been described. HCoVs 229E and NL63 belong to group I, and HCoVs OC43, -HKU1, and SARS-CoV belong to group II. Serogroups I and II have been isolated from mammals and serogroup III has been isolated from birds.

EPIDEMIOLOGY

Coronaviruses first were recognized as animal pathogens in the 1930s. Thirty years later, 229E and OC43 were identified as human pathogens, along with other coronavirus strains that were not investigated further and for which little is known regarding their prevalence and associated disease syndromes. In 2003, SARS-CoV was identified as a novel virus responsible for the 2002–2003 global outbreaks of SARS, which lasted for 9 months, infected 8096 people, and resulted in 774 deaths. Most experts believe SARS-CoV evolved from a natural reservoir of SARS-CoV-like viruses in bats through civet cats as intermediate hosts. Whether or not a large-scale reemergence of SARS will occur is debatable. Finding a novel HCoV sparked a renewed interest in HCoV research, and 2 years later, NL63 and HKU1 were identified as newly recognized HCoVs. One of the investigations has revealed that NL63 was present in archived human respiratory samples as early as 1981.
HCoVs other than SARS-CoV can be found worldwide. They cause most disease in the winter and spring months in temperate climates. Seroprevalence data suggest that exposure is common in early childhood, with approximately 90% of adults being seropositive for 229E, OC43, and NL63 and 60% being seropositive for HKU1. In contrast, SARS-CoV infection has not been detected in humans since early 2004, when 4 isolated cases of SARS with no associated transmission were identified in China and 2 isolated cases and a cluster of 11 cases (1 death) were identified in South East Asia related to breaches in biosafety practices in different laboratories culturing SARS-CoV.
The modes of transmission for HCoV other than SARS-CoV have not been well studied. However, on the basis of studies of other respiratory tract viruses, it is likely that transmission occurs primarily via a combination of droplet and direct and indirect contact spread. Which of these modes are most important remains to be determined, and the possible role of aerosol spread requires further study. For SARS-CoV, studies suggest that droplet and direct contact spread are likely the most common modes of transmission, although evidence of indirect contact spread and aerosol spread also exist. There is no evidence of vertical transmission of SARS-CoV.
HCoVs other than SARS-CoV are most likely to be transmitted during the first few days of illness, when symptoms and respiratory viral loads are at their highest. Further study is needed to confirm that this holds true for the NL63 and HKU1 viruses. SARS-CoV is most likely to be transmitted during the second week of illness, when both symptoms and respiratory viral loads peak.
The incubation period for HCoV infections, other than SARS-CoV, is estimated to be 2 to 5 days (median 3 days), primarily on the basis of studies with 229E. The incubation period for SARS-CoV is 2 to 10 days (median, 4 days).

DIAGNOSTIC TESTS

The 2002–2003 SARS outbreaks garnered renewed interest in better understanding the etiology of respiratory tract infections, and some clinical laboratories have since started offering comprehensive respiratory molecular diagnostic testing for non-SARS HCoVs using reverse transcriptase polymerase chain reaction assays. Diagnostic laboratory and clinical guidance for SARS is available on the Centers for Disease Control and Prevention Web site (www.cdc.gov/sars/index.html). Given the potential for false-positive test results and the associated public health implications, testing for SARS-CoV in the absence of known person-to-person transmission of SARS must be performed with caution and only in consultation with regional public health departments when there is a high degree of suspicion in a patient with no alternative diagnosis.
Specimens obtained from the upper and lower respiratory tract are the most appropriate samples for viral detection. Stool and serum samples also frequently are positive in patients with SARS-CoV. For 299E and OC43, specimens are most likely to be positive during the first few days of illness; whether this is also true for NL63 and HKU1 needs further study. For SARS-CoV, respiratory and stool specimens may not be positive until the second week of illness when symptoms and viral loads peak; serum samples are most likely positive in the first week of illness. Compared with adults, infants and children with SARS-CoV infections are less likely to have positive specimens consistent with the milder symptoms and presumed corresponding lower viral loads seen in this age group.

TREATMENT

Infections attributable to HCoVs generally are treated with supportive care. SARS-CoV infections are more serious. Steroids, type 1 interferons, convalescent plasma, ribavirin, and lopinavir/ritonavir all were used clinically to treat patients with SARS, albeit without benefit of controlled data documenting efficacy. No definitive conclusions regarding efficacy of any treatment can be made. There are reports of patients who were treated with supportive care only who recovered uneventfully. In the event that SARS-CoV reemerges, clarification of the effectiveness of treatments through controlled clinical trials is needed.

ISOLATION OF THE HOSPITALIZED PATIENT

Health care professionals should use Droplet and Contact Precautions in addition to Standard Precautions when examining and caring for infants and young children with signs and symptoms of a respiratory tract infection for the duration of their illness (www.cdc.gov/hicpac/2007IP/2007isolationPrecautions.html). Droplet Precautions may be discontinued when infectious agents that have been documented to be spread via the droplet route, such as influenza virus, adenovirus, rhinovirus, and SARS-CoV, have been ruled out. Airborne, Droplet, and Contact Precautions are recommended for patients with suspected SARS-CoV infection for the duration of illness plus 10 days after resolution of fever, provided respiratory symptoms are absent or improving.

CONTROL MEASURES

Practicing appropriate hand and respiratory hygiene likely is the most useful and easily implemented control measure to curb spread of all respiratory tract viruses, including HCoVs. For hospitalized patients, following additional infection control practices as described previously is recommended. The control of the 2002–2003 SARS outbreaks is credited to the rapid identification of cases and early implementation of infection control and public health measures, such as contact tracing and quarantine.
Coronaviruses, Including SARS Figure 1.
Microscopic appearance of control (A) and infected (B) Vero E6 cells, demonstrating cytopathic effects. The cytopathic effect of severe acute respiratory syndrome coronavirus on Vero E6 was evident within 24 hours after infection. Courtesy of Centers for Disease Control and Prevention
Coronaviruses, Including SARS Figure 2.
Electron micrograph of a coronavirus. Pleomorphic virions average 100 nm in diameter and are covered with club-shaped knobs.

Coronaviruses, Including SARS Figure 3.
Transmission electron micrograph of coronavirus OC43. Courtesy of Centers for Disease Control and Prevention
Coronaviruses, Including SARS Figure 4.
Coronaviruses are a group of viruses that have a halo or crown-like (corona) appearance when viewed in an electron microscope. Severe acute respiratory syndrome (SARS) coronavirus was the etiologic agent of the 2003 SARS outbreak. Additional specimens are being tested to learn more about this coronavirus and its etiologic link with SARS. Courtesy of Centers for Disease Control and Prevention
Coronaviruses, Including SARS Figure 5.
This scanning electron micrograph (SEM) revealed the thickened, layered edge of severe acute respiratory syndrome-infected Vero E6 culture cells. The thickened edges of the infected cells were ruffled and appeared to comprise layers of folded plasma membranes. Note the layered cell edge (arrows) seen by SEM. Virus particles (arrowheads) are extruded from the layered surfaces. Courtesy of Centers for Disease Control and Prevention.
Coronaviruses, Including SARS Figure 6.
This scanning electron micrograph (SEM) revealed the thickened, layered edge of severe acute respiratory syndrome-infected Vero E6 culture cells. The thickened edges of the infected cells were ruffled and appeared to comprise layers of folded plasma membranes. Note the layered cell edge (arrows) seen by SEM. Virus particles (arrowheads) are extruded from the layered surfaces. Courtesy of Centers for Disease Control and Prevention
Coronaviruses, Including SARS Figure 7.
Note the coronaviruses contained within cytoplasmic membrane-bound vacuoles, and cisternae of the rough endoplasmic reticulum. This thin section electron micrograph of an infected Vero E6 cell reveals coronavirus particles. Courtesy of Centers for Disease Control and Prevention
Coronaviruses, Including SARS Figure 8.
This scanning electron micrograph reveals the rosette-like appearance of the matured severe acute respiratory syndrome coronavirus particles (arrows). This scanning electron micrograph emphasizes the form and structure of the virus particle, or virion, made visible with negative staining (inset) under transmission electron microscopy. Short and stubby spikes are visible on the virus surface. Courtesy of Centers for Disease Control and Prevention.
Coronaviruses, Including SARS Figure 9.
Scanning electron microscopy (SEM) of Vero E6 cells infected with severe acute respiratory syndrome-associated coronavirus. (A) The cell surface is covered with extracellular progeny virus particles, and progeny virus particles are being extruded from or attached to numerous pseudopodia on the infected cell surface (arrows). (B) A higher magnification micrograph of the virus-clustered pseudopodia (arrows). (C) Rosette-like appearance of the matured virus particles (arrows). The SEM image complements the form and structure of the virus seen with negative staining (inset) under transmission electron microscopy. Short and stubby spikes are visible on the virus surface. (D) Arrows indicate virus particles being exported from the surfaces of the filopodia. Courtesy of Emerging Infectious Diseases.
Coronaviruses, Including SARS Figure 10.
Coronaviruses are a group of viruses that have a halo or crown-like (corona) appearance when viewed under an electron microscope. Courtesy of Centers for Disease Control and Prevention/C. S. Goldsmith and T. G. Ksiazek.
Coronaviruses, Including SARS Figure 11.
Using the NanoScope IV MultiMode atomic force microscope, the “knobby” virion surface structure was visualized (arrow). High magnification of the maturing virus particles showed a rosette appearance with short, knob-like spikes under both the scanning electron and atomic force microscopes. The spikes, which were 16-17 nm, seemed shorter than those of other coronaviruses. Courtesy of Centers for Disease Control and Prevention/Mary Ng Mah Lee, MD, National University of Singapore, Singapore.


Sumber : Ragaminformasi



Tidak ada komentar:

Poskan Komentar