Introduction
Hepatitis B virus (HBV) was identified over 40 years ago, but has probably evolved with humans over the last 35 000 years.Reference Allain and Candotti1 Two billion people have been exposed to HBV, 5 million cases of acute HBV infection occur annually and over 350 million people have a chronic infection.Reference Rimšelienė, Nilsen, Kløvstad, Blystad and Aavitsland2, Reference Hou, Liu and Gu3 Approximately 75 per cent of chronic carriers live in Asia and the Western Pacific region.Reference Hou, Liu and Gu3
Hepatitis B virus is transmitted parenterally by contaminated blood or other body fluids through blood vessels, skin or mucous membranes. The virus can be detected in all human body fluids: the virus concentration is highest in blood or serous exudates, and is relatively low in saliva, semen and vaginal fluids.Reference Kwon and Lee4
Some authors have suggested that cerumen can be a potential source for the transmission of HBV and human immunodeficiency virus (HIV).Reference Goh, Son, Kong, Chon and Cho5 However, there is little information available in the current literature on the potential role of cerumen in HBV transmission.
This study aimed to investigate the presence of HBV DNA in the cerumen of HBV-infected patients.
Materials and methods
The study group consisted of 30 adult patients with chronic hepatitis B, who were admitted to our hospital between August 2010 and July 2011. Chronic HBV infection was confirmed by the presence of hepatitis B surface antigen and the absence of hepatitis B surface antibodies in serum over a period longer than six months.
Samples of serum and cerumen were obtained on the same day and were examined simultaneously. All patient serum samples were tested for HBV serological markers. Hepatitis B surface antigen and hepatitis B surface antibodies were detected with enzyme immunoassay systems (Architect i2000; Abbott Diagnostics, Abbott Park, Illinois, USA). The cerumen samples were collected by an expert otolaryngologist, who used an otological microscope: this was to avoid any trauma to the ear canal and possible contamination of it with patients' blood. Cerumen samples were collected in sterile Eppendorf tubes containing 0.5 ml saline. Hepatitis B virus DNA was detected in cerumen using a polymerase chain reaction test (Roche Diagnostics, Indianapolis, Indiana, USA).
Results
There were 5 female and 25 male patients. Patients' ages ranged from 24 to 68 years, with an average patient age of 45.6 ± 13.2 years. All patients were positive for hepatitis B surface antigen and negative for hepatitis B surface antibodies.
Hepatitis virus DNA was detected in the cerumen samples of 2 out of the 30 patients (6.6 per cent).
Discussion
Hepatitis B virus infection is a major global public health problem.Reference Lavanchy6 According to the European Association for the Study of the Liver, about one-third of the world's population have serological evidence of past or present HBV infection, and more than 350 million people worldwide may be affected by chronic HBV infection.Reference Ocana, Casas, Buhigas and Lledo7 Hepatitis B virus is a ‘silent killer’ disease of the liver, and many carriers of the disease do not realise that they are infected.Reference Khan, Shams, Qureshi, Israr, Khan and Sarwar8 It is a primary cause of cirrhosis and hepatic cellular carcinoma, and is among the top 10 causes of death.Reference Torbenson and Thomas9 In fact, 73 per cent of all liver cancer deaths worldwide are due to hepatitis viruses, with much higher proportions in low and middle income countries.Reference Ott, Stevens, Groeger and Wiersma10 Hepatitis B virus infection is a more communicable disease than HIV or hepatitis C virus infection (HCV). The risk of HBV infection is 50–100 times higher than HIV and 10 times higher than HCV.Reference Khan, Shams, Qureshi, Israr, Khan and Sarwar8
Hepatitis B virus is present in body fluids such as blood, saliva, semen, vaginal secretions and the menstrual blood of infected individuals. As HBV is resistant to breakdown outside of the body, it is readily transmitted from person to person via contact with infected body fluids.Reference Tsai, Lin, Lin and Liou11
Goh et al. analysed 30 cerumen and 5 otorrhoea samples of 30 patients with chronic hepatitis B; HBV DNA was detected in 20 samples of cerumen (66.7 per cent) and in all 5 otorrhoea samples (100 per cent).Reference Goh, Son, Kong, Chon and Cho5 Kalcioglu et al. examined 40 patients with HBV (indicated by positive serum samples); HBV DNA was found in 11 of the 40 cerumen specimens (27.5 per cent).Reference Kalcioglu, Durmaz, Ozturan, Bayindir and Direkel12 In our study, HBV DNA was detected in the cerumen samples of 2 out of 30 patients (6.6 per cent). Hence, the results of this study and those of previous studies indicate that cerumen can be a potential source of transmission of HBV.Reference Goh, Son, Kong, Chon and Cho5, Reference Kalcioglu, Durmaz, Ozturan, Bayindir and Direkel12
Variations in the results of these studies (i.e. the lower percentage of HBV DNA in cerumen samples in the present study) may be due to the different methods of sampling used. In the studies by Goh et al. and Kalcioglu et al. the method of cerumen collection was not clearly described and we do not know whether this was done by an otolaryngologist using a microscope or not. In our survey, the cerumen samples were collected by an expert otolaryngologist using an otological microscope. This avoided any trauma to the ear canal and possible contamination of it with patients' blood, thereby preventing false positive results.
• This study investigated hepatitis B virus (HBV) DNA in the cerumen of infected patients
• The results indicate that cerumen can potentially transmit HBV
• Otologic patients must be managed with appropriate precautions, to avoid virus transmission
Hepatitis B virus infection depends on the level of infection and the immunocompetence of the host. The mere presence of HBV DNA in cerumen does not indicate a considerable risk of infection in immunocompetent persons. The more important factor is the titre of HBV DNA in cerumen. We recommend carrying out a quantitative analysis of HBV DNA in cerumen; this is a more expensive but sophisticated approach. In 2008, the European Association for the Study of the Liver defined occult HBV infection as the presence of HBV DNA in the liver (with detectable or undetectable HBV DNA in the serum) of individuals who test negative for HBV surface antigen using currently available assays.Reference Raimondo, Allain, Brunetto, Buendia, Chen and Colombo13 If we add these hidden cases to the cases of known and unknown HBV carriers, the role of precautions (for infection control) when managing otologic patients will be much more important.
