Date Published: March 17, 2017
Publisher: Public Library of Science
Author(s): Ronaldo Bragança Martins, Lucas Penna Rocha, Mirela Moreira Prates, Talita Bianca Gagliardi, Balduino Biasoli, Marcelo Junqueira Leite, Guilherme Buzatto, Miguel Angelo Hyppolito, Davi Casale Aragon, Edwin Tamashiro, Fabiana Cardoso Pereira Valera, Eurico Arruda, Wilma Terezinha Anselmo-Lima, Oliver Schildgen.
Respiratory viruses are frequently detected in association with chronic tonsillar hypertrophy in the absence of symptoms of acute respiratory infection (ARI). The present analysis was done in follow-up to a previous clinical study done by this same group. Nasopharyngeal washes (NPWs) were obtained from 83 of 120 individuals at variable times post adenotonsillectomy, in the absence of ARI symptoms. A look back at virus detection results in NPWs from the same 83 individuals at the time of tonsillectomy revealed that 73.5% (61/83) were positive for one or more viruses. The overall frequency of respiratory virus detection in post-tonsillectomy NPWs was 58.8%. Rhinovirus (RV) was the agent most frequently detected, in 38 of 83 subjects (45.8%), followed by enterovirus in 7 (8.4%), human metapneumovirus in 6 (7.2%), human respiratory syncytial virus in 3 (3.6%) and human coronavirus in 1 (1.2%). Remarkably, there was no detection of adenovirus (HAdV) or human bocavirus (HBoV) in asymptomatic individuals in follow-up of adenotonsillectomy. In keeping with persistence of respiratory DNA viruses in human tonsils, tonsillectomy significantly reduces asymptomatic shedding of HAdV and HBoV in NPWs.
A wide range of respiratory viruses can be detected in human adenoids and palatine tonsils [1, 2, 3, 4]. A previous cross-sectional study of hypertrophic tonsils and nasopharyngeal secretions from patients undergoing adenotonsillectomy revealed very high frequencies of detection of respiratory viruses by PCR . Overall, 97% of 120 individuals without symptoms of acute respiratory infection (ARI) had at least one respiratory virus detected by RT-PCR in either adenoid, palatine tonsil, or nasopharyngeal washes (NPWs). Considering only NPWs, 78.5% were positive for one or more viruses . Those results prompted us to assess whether asymptomatic shedding of respiratory viruses is also frequent in asymptomatic individuals whose tonsils were removed. To address that question, NPWs collected from asymptomatic subjects in follow-up of adenotonsillectomy  were tested for a comprehensive respiratory virus panel.
The study was conducted according to the principles expressed in the Declaration of Helsinki and was approved by the Ethics Review Committee of the Hospital das Clínicas de Ribeirão Preto (Number 10466/2008) and a written informed consent was obtained from all parents and guardians prior to enrollment.
A look back to the previous results of virus detection obtained for the same 83 patients  revealed that at least one virus had been detected in 73.5% of the NPWs collected immediately prior to tonsillectomy. At that time, respiratory viruses were detected in 90.3% of adenoids and 77.1% of palatine tonsils from the same 83 patients. The overall frequency of virus detection in the NPWs from the same individuals a few years after adenotonsillectomy was 58.8%, and all patients were free of symptoms of acute respiratory infections for at least one month prior to sample collection. The overall rate of viral detection in samples from 20 control individuals was 14/20 (70%).
Asymptomatic respiratory shedding of HAdV and HBoV is significantly reduced by tonsillectomy, which agrees with persistence of respiratory DNA viruses in human tonsils.