Article
Following on from the paper ‘Orofacial Viral Infections – an Update for Clinicians’ by RG Nair et al in the July/August issue (Dent Update 2014; 41: 518–524), an interesting overview, for completeness it is important to point out that some of these infections can be more serious than mentioned and that others, unmentioned, are increasingly encountered.
For example, the enteroviruses which, in addition to Coxsackieviruses, can cause hand-foot and mouth disease (HFMD) can be dangerous. Human enterovirus species A (HEV-A) consists of at least 16 members of different serotypes that are known to be the causative agents of HFMD and herpangina, but also other diseases, such as respiratory disease and polio-like flaccid paralysis. Enterovirus 71 (EV71) and Coxsackievirus A16 (CVA16) are Picornaviridae, genus Enterovirus, species A and are the major causative agents of HFMD. Infections involving EV71, but not CVA16, can progress to severe neurological disease, including aseptic meningitis, encephalitis, acute flaccid paralysis and neurogenic pulmonary oedema. EV71 is thus considered to be a neuropathogenic virus and EV71 outbreaks have become a major public health concern. Not only can EV71 HFMD on occasions rapidly progress to cardiopulmonary failure, but so can cases associated with adenoviruses.1
CVA5, CVA6, CVA10 and CVA12 mainly cause herpangina or are occasionally involved with sporadic cases of HFMD. Various genetic types respond differently to these viruses.2,3 For example, the human scavenger receptor class B, member 2 (SCARB2) is a cellular receptor for EV71 and CVA16; HEV-A viruses can be divided into at least two groups, depending on their use of SCARB2, and the receptor usage plays an important role in developing the specific diseases for each group.
There are also other viral infections not mentioned that, although most common in the resource-poor world, are being encountered by travellers and, in the resource-rich world and, with continually increasing global travel, are appearing or will appear in the most unexpected places, including the UK.
Ebola virus disease (EVD), formerly termed Ebola haemorrhagic fever, is a severe, often fatal (up to 90%), viral illness caused by one of five species of the filovirus. Fruit bats are considered to be the natural host and the virus is transmitted to humans and spreads through human-to-human transmission. EVD outbreaks have primarily been in remote villages in Central and West Africa and Ebola has not, at time of writing (2014, August 1), appeared in the UK. EVD presents with the sudden onset of high fever, chills, headache, myalgia, anorexia, nausea, abdominal pain, sore throat and profound prostration. In some cases, on around the fifth day of the acute phase, an exanthematous rash appears on the trunk with widespread haemorrhagic manifestations, such as haemorrhagic conjunctivitis, bleeding ulcers in the mouth and on the lips and from the gingiva, haematemesis, melaena, epistaxis, ear bleeding, and haematuria.4,5 Most haemorrhagic cases have had a fatal outcome within about a week. No specific treatment or vaccine is available.
Dengue fever (DF) is an acute mosquito-borne disease caused by the DF virus of the family Flaviviridae, and is globally the most common cause of arboviral disease. It is endemic in more than 110 countries, predominantly in the tropics. Clinical manifestation of dengue range from fever, headaches, arthralgia, myalgia and rashes to severe haemorrhagic shock and death.6 Oral manifestations may include acute gingival7 or post-extraction8 bleeding, and patients with dengue neurological sequelae (taste abnormalities) have been reported from the UK.9 There are no cures or specific drug treatments.
O'nyong-nyong refers to a disease seen in Africa, not (yet) in the UK, resulting from infection by an alphavirus, a togavirus, transmitted by anopheline mosquitoes causing joint pains, lymphadenopathy, and fever. Lesions have been noted on the oral mucous membranes but there are no formal descriptions in the literature.10 There are no cures or specific drug treatments but no fatalities due to infection are known.
Chikungunya fever, caused by a togavirus transmitted by the Asian Tiger mosquito (Aedes albopictus) is endemic mainly around the Indian Ocean and has been found in Africa, the Indian subcontinent and Southeast Asia, particularly the Philippines, Thailand, Cambodia, Vietnam, Mauritius, Taiwan and Sri Lanka, as well as southern Europe, Ireland, Australia, the Caribbean and Venezuela, and the United States. With an incubation of 2–4 days, it may cause a fever to 39 degrees and a central maculopapular rash, with headache, malaise and arthralgia and thus is similar to dengue and O'nyong-nyong. Oral features reported include ulceration and candidosis.11,12 There are no cures or specific drug treatments but fatalities are uncommon.
The above infections are not uncommon in some areas of the world and can sometimes have orofacial lesions. Early medical intervention can be crucial. Thus the continuing awareness of dental professionals to these issues; the taking of a travel/contact history; and prompt referral are important. One has only to recall the past devastation from infections such as diphtheria, plague, poliomyelitis, rabies, smallpox and tuberculosis to be conscious of the threats from the worldwide movement of people which are surely only increasing. Finally, we need to be prepared with appropriate prophylaxis and healthcare facilities; falling immunizations have already resulted in epidemics across the world of infections such as diphtheria and plague; polio has not gone away and tuberculosis is not uncommon – indeed, one third of the world population is infected! Closing facilities can be a dangerous road. My training at the Royal Free Hospital (RFH) London, 40 years ago, included treating the first UK patient with Lassa fever (like Ebola, a potentially lethal acute viral haemorrhagic fever emanating in West Africa), in a single High Level Isolation Unit (HLIU) bed in a specialized hospital with half a dozen wards for infectious diseases (one of several hospitals in the UK with this remit); we are told there is now only one HLIU for such dangerous infections in the UK, and this is at RFH (https://www.royalfree.nhs.uk/services/services-a-z/infectious-diseases/high-level-isolation-unit/), and the number of beds according to the media is in single figures – possibly two only. (I hope this is wrong!).
If these infections continue to spread, as seems likely, let us show no surprise if health cuts have serious implications.
NHS says there is very low chance of Ebola in the UK, an epidemic even more so due to the way Ebola spreads to read more visit http://www.theguardian.com/world/2014/oct/08/ebola-gearing-up-uk-unlikely