Rapid and accurate detection of coronavirus is crucial to control the epidemic

Publicação: 11 de March de 2020

A study has demonstrated that Covid-19 was detected in the self-collected saliva of 11 of the 12 surveyed patients

Saliva is a promising non-invasive sample for diagnosis, monitoring and infection control in patients with Covid-19

To the moment, the virus known as Covid-19, previously called Chinese Coronavirus, has killed +5.800 and infected over 155 thousand people. Also, about 72 thousand patients recovered after contracting the infection, according to the interactive map from Johns Hopkins University. Rapid and accurate detection is crucial to control the outbreak in the population and in hospitals. A study published in the Oxford Journal, entitled “Consistent Detection of 2019 Novel Coronavirus in Saliva, reports that the live virus was detected in saliva by viral culture in 11 of the 12 patients with the new coronavirus infection. Saliva is a promising non-invasive sample for diagnosis, monitoring and control of infection in patients with Covid-19.

Clinical Associate Professor of the Department of Microbiology at the Hong Kong University School of Medicine (HKU), Dr. Kelvin Kai-Wang To, one of the authors of the research, explains that currently, nasopharyngeal aspirate or nasopharyngeal swab are the ideal types of samples for the detection of respiratory viruses. However, collecting nasopharyngeal samples is an uncomfortable procedure for the patient and is also a risk for healthcare professionals. “In recent years, we and others have found that there is a high correlation between saliva and nasopharyngeal samples in the detection of respiratory viruses. Therefore, during the current new coronavirus epidemic, we have chosen to use saliva for serial monitoring, in order to reduce patient discomfort and the risk of infections of healthcare professionals. We found that saliva was detected in 11 of the 12 patients with the new coronavirus infection. We also showed that saliva can be used for serial monitoring of patients with the new coronavirus infection”, he highlights. However, data on the use of saliva for the diagnosis of the new coronavirus are preliminary and should be interpreted with caution.

The survey tested the saliva of 12 patients in Hong Kong with confirmed Covid-19 infection (via RT-qPCR and viral culture), based on clinical and epidemiological criteria, as described by the Hong Kong Health Protection Center. Covid-19 was detected in the self-collected saliva of 91.7% (11/12) of the patients. The monitoring of the viral load of the serial saliva showed a decreasing trend. Viral cultures were positive in three patients and negative in two patients. Because saliva samples can be provided easily and invasive procedures are not required, saliva collection can greatly minimize the chance of exposing healthcare professionals to Covid-19.

New saliva test reveals Covid-19 in 15 minutes

A new exam with Israeli technology developed by Dr. Amos Danielli, from Bar-Ilan University, reveals the presence of the coronavirus in 15 minutes. The method, which uses genetic material from patients’ saliva, consists of detecting virus-specific RNA sequences and attaching their RNA to a fluorescent molecule that emits light when illuminated by a laser beam. However, very low concentrations of RNA in the patient’s genetic material can emit a signal so low that existing devices simply cannot pick it up, even if the sample is infected. The current diagnosis takes about an hour. The new method has been proven effective in identifying the Zika virus and is used in the central virology laboratory of the Israeli Ministry of Health.

App uses saliva and smartphone to detect Covid-19

Engineers at the University of Cincinnati, in the United States, have developed a mini portable laboratory that can be connected to a smartphone and diagnose infectious diseases, such as the coronavirus. A drop of blood or saliva deposited on the device’s own chip is enough for the diagnosis. The patient must put the chip in the mouth and then plug it into the custom slot. The device then automatically transmits the results to the physician through an application. The chip uses technology that observes the tendency for a liquid to stick to the surface to extract a two-channel sample. While one channel mixes the sample with lyophilized detection antibodies, the other contains lyophilized luminescent material to read the results when the split samples are combined again into three sensors. In addition to the coronavirus, it is possible to identify HIV, malaria and other diseases.

Early to predict end of epidemic

For Dr. Kelvin Kai-Wang To, an effective vaccine is very important for the new coronavirus for a few reasons. First, the new coronavirus can cause serious illness, especially among the elderly and people with chronic diseases. Second, this new virus spreads very quickly and can be difficult to eradicate. There is a possibility that this virus will continue to circulate for a long time. An effective vaccine will reduce the burden of infection in healthcare facilities. Third, the effectiveness of antiviral treatment is uncertain at this point. Most of the treatments being studied have side effects.

Among the main threats in relation to Covid-19, Dr. Kelvin Kai-Wang To points out that the virus can continue to circulate and spread to other places. “It is particularly worrying if it spreads to places where medical care is suboptimal. In addition, the outbreak has led to a sudden increase in the demand for surgical masks and other personal protective equipment, and there is currently a shortage of masks worldwide. Finally, the new virus is also a threat to economic and social activities. As observed in mainland China and Hong Kong, it has already caused serious disruptions in many economic and social activities”, he adds.

Still according to the professor at the University of Hong Kong, Covid-19’s main challenge is to identify effective treatments and vaccines. “This task may not be easy. For example, despite many years of research, there are still very few antivirals and vaccines to treat respiratory viral infections. In addition, during the epidemic, there are many uncertainties. There is panic and fear among the population. It is very difficult to predict what we can expect in relation to Covid-19 in the upcoming weeks and months. “Hopefully, with strict control measures, the epidemic can be controlled”, he concludes.

Brazil’s preparation for Covid-19

The Director of Immunization and Surveillance of Communicable Diseases of the Ministry of Health, Dr. Julio Croda, stressed that the disease caused by the new coronavirus (Covid-19) poses a great challenge in terms of public health. “Brazil’s preparation for the arrival of this new virus has been exemplary and shows the importance of the Unified Health System (SUS) in all its spheres in responding to public health emergencies. In January 2020, Brazil activated the Emergency Operation Center which, through a single command, has been guiding services and health professionals through epidemiological bulletins, SOPs, treatment manuals for the new coronavirus and daily press conferences”, he emphasizes. Still according to Dr. Croda, it is worth mentioning the transparency that the Ministry of Health has been showing to the media in press conferences, interviews and information platform (www.plataformasaude.com.br), daily updated with the number of suspected and confirmed cases from the world and Brazil .

In addition, a contingency plan was prepared and the portfolio assists the 27 states in the organization of the Health Care Network and in the preparation of the respective contingency plans, as well as training with the Pan American Health Organization (PAHO) for the three reference laboratories for carrying out the RT-PCR test for SARS-CoV2. “Currently, the average time for specific diagnosis is around three days and suspicious cases are being dismissed or confirmed quickly. We entered phase 3. States and municipalities are preparing their primary and specialized care services to reduce local transmission and, in the future, provide adequate assistance to the most serious cases and mitigate the number of deaths”, concludes the director of Immunization and Surveillance of Communicable Diseases of the Ministry of Health.

Covid-19 risks while traveling

The city of Wuhan is the largest city (11 million) in central China, it has characteristics that contributed to the important local transmission of Covid-19, it has an important transport center and a center for industry and commerce, it houses the largest railway station, the largest airport and the largest port in central China. About 30,000 passengers fly daily from Wuhan to destinations worldwide. In 2018, more than 24.5 million passengers passed through Wuhan airport.

The Infectologist Physician, Dr. Tânia Chaves, member of the Commission for Vaccines for Travelers of the Sociedad Latinoamericana deMedicina del Viajero (SLAMVI), recalls that emerging and reemerging pathogens represent an important challenge for global public health, the ease of human displacement, the size and reach of the network of international air travel contributes greatly to the rapid dispersion of new and old pathogens. Travelers are considered to be sentinel populations for the introduction and reintroduction of emerging and reemerging pathogens with the potential for rapid spread around the world.

In face of the current Covid-19 epidemic in China, and with local transmission already observed in other countries, SLAMVI considers the situation of high risk for acquiring the disease in travelers going to areas with local transmission. In a recent publication of SLAMVI’s expertise, it recommends that non-essential travel should be avoided to China and the affected countries (with defined local transmission) which, with the announced change of criteria for suspected cases, now also includes people from countries like; Japan, South and North Korea, Singapore, Vietnam, Thailand and Cambodia, in addition to China that was already on the alert, among other measures such as:

In case of symptoms such as fever, cough and breathing difficulties, use a face mask (surgical) and seek assistance from health services.

Follow other works published this year with the participation of Dr. Kelvin Kai-Wang To

Genomic characterization of the 2019 novel human-pathogenic coronavirus isolated from a patient with atypical pneumonia after visiting Wuhan

A familial cluster of pneumonia associated with the 2019 novel coronavirus indicating person-to-person transmission: a study of a family cluster

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