Coronavirus Disease 2019: Implications to the Field and Practice of Oral Pathology

Objective: To highlight the implications of COVID -19 disease to the field and practice of Oral Pathology. Materials and Methods: Extensive PubMed and Google Scholar search using relevant mesh terms for articles on the effects of COVID-19 on the practice of Oral Pathology. The relevant articles were thereafter reviewed, and the implications drawn. Results: The virus which is usually transmitted via droplet can survive for days on some materials which are commonly used in the laboratory; thereby constituting a potential source of infection to laboratory workers. In addition, the presence of the viral receptors in the oral mucosa has been established and so presenting the mouth as a possible route of entry. Viral particles are also shed heavily in the saliva. These observations have dual implications. First, it poses increased risk to the oral pathologists in handling oral tissue biopsy and secondly, it potentially makes the saliva an alternative medium of diagnosis. Furthermore, oral exfoliative cytology can be developed for viral detection especially in asymptomatic patients. Conclusion: Maintenance of social distance while attending to patients in the laboratory, regular disinfectant of the working surfaces and careful handling of tissue specimens are essential for preventing the spread of COVID-19 in the laboratory. Research works in the use of saliva and oral exfoliative cytology for screening and diagnosis of COVID-19 patients should be a new area of interest to the oral pathologists.


Introduction
Taxonomy of Viruses (ICTV) has renamed this novel infective virus Severe Acute Respiratory Syndrome The coronavirus disease 2019 simply called COVID- 4 Coronavirus-2 (SARS-CoV-2) . 19, is caused by a novel coronavirus, and was first reported in the city of Wuhan, Hubei Province, China Oral and maxillofacial pathology (called oral 1 pathology in some centres) is a speciality that is in December, 2019 . Since then, it has grown to involved with the diagnosis and study of the causes become a major global pandemic. On January 30, and effects of diseases affecting the oral and 2020, the World Health Organization (WHO) maxillofacial region (i.e. the mouth, the jaws, the face declared COVID-19 a public health emergency of and the associated structures). It can be considered a international concern which has affected millions of 2 people worldwide and causing several deaths . As at speciality of dentistry and pathology. Oral pathology July 2020, the total number of people infected is a close ally of oral and maxillofacial surgery and oral worldwide has exceeded fourteen million with over medicine specialities. In the process of making need to make close contact with the patients and /or workers and those in the clinic. In hospitalized cases, patients products which are potentials risk factors for aggravated conditions may give rise to pneumonia, the COVID-19 infections. Products from patients are multiple organs failure (mainly renal failure) and even also analysed in search for possible markers for death. The case fatality ratio declared by the WHO for 9 COVID-19 infection is about 4.5% . Currently, the screening and diagnosis of oro-facial lesions and development of vaccines and drugs is still on going, other related systemic diseases.
hence, the best strategy to limit this deadly infection In this article, a critical review of published articles on is social distancing, contact tracing and vigorous COVID-19 was done to determine the implications of testing to identify and quarantine the positive cases. the infection on the field and practice of oral For the health care provider, the use of personal pathology as well as potential role of the oral protective equipment and regarding all patients as pathologists in the screening, diagnosis and potential carrier will help to prevent the infection. management of the novel disease.

Oral manifestations of COVID-19 infection Pathogenesis of COVID-19 infection
Manifestation seen within the oral cavity of patients The aetiological agent of COVID-19 infection is a with COVID-19 infection may include the following; novel coronavirus known as SARS-CoV-2; a member oral ulceration, gingival bleeding, glossitis, oral pain, of the order Nidovirales, family Coronaviridae, and halitosis. A recent publication suggested that genus, Betacoronavirus (β-CoV). Its nucleotide is recurrent oral ulcers may be the initial symptom of 80% similar to SARS-CoV and 50% similar to MERS- 11 this infection . Xerostomia has also been reported CoV which are other coronaviruses known to cause 5 in a relatively high proportion of patients with COVIDepidemics in humans . SARS-CoV-2 structure 12 19 . Hence, it may sometimes become necessary to consists of a nucleocapsid with a single stranded RNA perform oral examination and intervention in patients core and a lipoprotein envelope with numerous with COVID-19. spikes with which it attaches to angiotensin converting enzyme 2 (ACE 2) receptors on human Diagnosis of COVID-19 infection cells to exert its effect.
The main strategy for identification of COVID-19 is Transmission of COVID-19 is usually through Reverse Transcription quantitative Polymerase Chain inhalation of respiratory droplets from infected Reaction (PCR), which is commonly used to extract individuals. These droplets can be generated through viral RNA from oropharyngeal and nasopharyngeal coughing, sneezing and talking. COVID-19, like other 13 swabs or sputum samples . Also, serological testing coronaviruses, can also be contracted from infected 0 aimed at detecting antibodies to the virus in the surfaces. It is known that at 24 C, coronaviruses can blood of the patients has been suggested as a survive for about 5 days in the sputum and faeces, 10 14 possible means of diagnosis . days in urine and blood. Thus, the possibility of faeco-oral transmission is very high. At room Use of saliva in the diagnosis of COVID-19 temperature, it could survive for about 3-5 days on The use of PCR technique is very expensive and is not the surfaces of filter paper, gauze, plastic, ceramic readily available in a resource limited area like and glass which are often present in the laboratories, 6 Nigeria. Serological test is also not very reliable thereby putting the laboratory works at risk . Also, because antibody may not be detected in all patients through contact with infected surfaces and aerosols, that have the infection. Taking the oropharyngeal or mucosa infection can occur. This is made possible nasopharyngeal swab is very irritating and because of the presence of ACE 2 receptors on 7 discomforting to most individuals and some patients mucosae epithelia including the oral mucosa .
may not be able to tolerate the procedure. Thus, Once it finds a human host, the incubation period of some authors have suggested the use of saliva this virus has been reported to be 2-14 days, but it 12,13.15 8 because the virus can be detected in medium . It can extend up to 24 days . The common symptoms has been documented that thus far, three methods of of COVID-19 are fever, chills, fatigue, shortness of sample taking capture saliva: saliva swabs, coughing breath and dry cough. Other uncommon symptoms out, and directly sample from the salivary gland duct. are sore throat, muscle pain, diarrhoea, As regards clinical applications where a strong conjunctivitis, loss of taste or smell, headache, skin 9 positive rate of virus identification is required, saliva rashes on the fingers and or toes . Most of the from deep throat provides the strongest positive infected individuals show mild or no symptoms and 10 rate, which could enhance early-diagnosis of COVIDare known as carriers . These people are potential 12 19 . Saliva extracted from salivary gland ducts is sources of infection to unsuspecting laboratory consistent for detecting acute COVID-19, thus may Implications of COVID-19 to Oral Pathology likely be a reliable and non-invasive test for acute efficient tool for the detection of asymptomatic 18 cases . This method is less time consuming, cheaper patients. The benefits of salivary diagnostic tests 18 are:-being economical, non-invasive, healthier to and very reliable . The oral pathologists are expected apply than serum sampling, diagnostic values in realto be in the fore front of researches using saliva and time, no requirement for specialized healthcare exfoliative cytology as a better alternative to the workers, numerous samples are simple to obtain, current method of diagnosis and screening. collecting and monitoring are achievable at home, Implications to the field and practice of oral minimizing the possibility of cross-infection, better pathology shipping and storage than serum sampling, much less agitation during the diagnostic process, screening The main route of spread of the infection through assays are commercially available, more so, saliva droplets infection implies that those working in the does not clot and can be handled more efficiently laboratory are also potentially exposed to being than blood. Thus, salivary diagnostic testing can offer infected by patients and other carrier visitor to the a convenient and cost-effective mechanism for earlylaboratory as well as co-workers. Also, the fact that 16 diagnosis of COVID-19 . the virus particles can survive on paper gauze, plastic, ceramic and glass for days means they can serve as Use of exfoliative cytology in the diagnosis of potential reservoir for infecting laboratory workers COVID- 19 because these materials are commonly used in oral pathology laboratory. Thus, the need to observe the The use of PCR as stated earlier is very expensive and prescribed preventive procedures such as is not readily available in resource limited areas and maintaining social distancing, wearing of face mask thus cannot be used to test every suspected cases.
by both the workers and visitors to the laboratory Also, asymptomatic patients which form about 80% alongside with regular cleaning of the work surfaces of cases may not come forward for testing even when with potent disinfectants is recommended. the test is available. Thus, it is important to develop a method of screening for COVID-19 which can be The incubation period of the virus is 2-14 days, the deployed for the whole population. ACE 2 receptor implication of this is that laboratory and oral has been identified as the attachment domain for diagnosis clinic workers exposed to suspected or 7 spike receptors on COVID-19 virus . Furthermore, diagnosed cases need to self-isolate for 14 days. If attachment of spike receptor also causes depletion they develop symptoms during this period, they will of ACE2 receptors, which leads to various morbidities need to take the diagnostic test to determine their 17 of the infection . Thus, due to changes in the status. Those that do not develop symptom would expressivity, ACE 2 expression can be exploited for also be encouraged to take the test if available 18 the detection or screening of COVID 19 . ACE 2 considering they could become asymptomatic receptors are readily available on oral epithelium and carriers, so potential spreader of the infection. 7 can be the route of COVID 19 infection . Exfoliative The dentist including the oral pathologist especially cytology is routinely used in oral pathology practice those working in the oral diagnosis clinic need to be for obtaining oral epithelial cells for investigation.
familiar with the oral manifestation of the infection. With this technique, it is possible to retrieve cells This may aid in the diagnosis of suspected cases or from the deeper basilar and supra-basilar location. some asymptomatic carriers. Currently, the Hence, it is possible to retrieve COVID-19 positive development of possible vaccine for this infection is epithelial cells from infected patients. This still far from being concluded, yet, oral pathologists knowledge can be exploited for early detection of have to continue to see patients both in the clinics infection. Apart from routine haematoxylin and eosin and in the laboratories. Therefore, the need to treat stain, immunohistochemistry can be used on the all patients as possible carriers and observe all exfoliated cells to identify and quantify various preventive protocols is imperative. Personal 19 proteins . Protein structures are better preserved in protective equipment should be used at all time to exfoliated cells as compared to formalin-fixed protect the health workers and the patients alike. paraffin-embedded tissues. Hence, better sensitivity and specificity can be achieved on exfoliative Conclusion cytology immunohistochemistry. Immunohisto-COVID-19 is highly infective and the spread is chemistry compatible anti-ACE2 antibodies are through droplet contamination. It is currently readily available with the reputed biotechnology diagnosed by identifying the causative agent in companies. Therefore, identification and oropharyngeal or nasopharyngeal swab using PCR quantification of the ACE2 receptor on exfoliated method. The oral pathologist can champion cells using immunohistochemistry could be an researches using saliva and oral exfoliative cytology in