**5.13. Zoonotic viral pneumonias**

**5.11. Rhinovirus**

200 Contemporary Topics of Pneumonia

with CAP [58].

**5.12. Varicella-zoster virus**

Many reports from the literature report that rhinovirus accounts for approximately 30% of cases of all virus-related pneumonia. Rhinovirus is considered the second most frequently recognized agent associated with pneumonia and bronchiolitis in the young. The virus is

Rhinovirus is genetically diverse with more than 100 serotypes identified. In addition to common colds, reports have suggested that rhinovirus is associated with bronchiolitis, bronchitis, pneumonia and acute asthma exacerbation. Rhinovirus has been detected by molecular methods in 10–30% of hospitalized children with lower respiratory tract infections. Rhinovirus is also considered to be the second most common cause of bronchiolitis after respiratory syncytial virus (RSV) [57]. Rhinoviruses have long been known to cause common colds and exacerbations of Chronic obstructive pulmonary disease (COPD), but because rhinoviruses grow poorly at 37°C lower respiratory tract infections were thought to be rare. However, it has been demonstrated that rhinoviruses can replicate at body temperature and infect cells of the lower respiratory tract. Molecular studies have consistently identified rhinoviruses in nasopharyngeal or pharyngeal specimens from children and adults with lower respiratory tract infections. Rhinovirus has also been detected in 2–17% of adults and 4–45% of children

Varicella-zoster virus (VZV) is a highly contagious herpes virus and primary infection manifests as chickenpox. The reactivation in later life results in zoster (shingles). It is spread by the respiratory route or direct contact with skin lesions. This pneumonia is rare in otherwise healthy children but does occur in immunocompromised children causing life-threatening complications [59]. VZV-related community-acquired pneumonia (VZV-CAP) has become increasingly recognized as a very serious and life-threatening complication invasive mechanical ventilation in more than half of the cases. Complications include secondary bacterial infections, encephalitis, hepatitis, and, with concomitant aspirin use, Reye syndrome. VZV pneumonia also tends be more severe in individuals who smoke. In fatal cases of pneumonia, laboratory findings include extensive alveolar hemorrhage, pulmonary edema and mononuclear cell infiltration with histological evidence of intranuclear inclusion bodies.

Varicella-zoster virus pneumonia is a serious complication of disseminated varicella-zoster virus infection with mortality rates of 9–50%. In adults prevalence of varicella-zoster virus pneumonia has varied from 5 to 50% of all varicella infections. Varicella-zoster virus is a self-limited benign disease in children known as chickenpox. But in adults it causes significant complications such as varicella-zoster virus pneumonia and over 90% of cases occur in patients with lymphoma and immunocompromised patients. Patients exhibit diffuse alveolar damage, spherical nodules are seen throughout the lung parenchyma. The nodules are

composed of an outer fibrous capsule enclosing areas of necrotic tissue [60].

associated with asthma hospitalizations in both old and young patients [56].

Zoonotic viral pneumonias include those caused by avian influenza, hantavirus, severe acute respiratory syndrome (SARS), and H1N1 (swine) influenza. In 1997, an influenza virus (H5N1 virus) which normally only infects only birds was found to infect humans In Hong Kong. Manifestations included pneumonia, which in some cases led to fatal acute respiratory distress syndrome (ARDS) or multisystem organ failure. The rising incidence and widespread reporting of disease from H5N1 influenza viruses can probably be attributed to the increasing spread of the virus from existing reservoirs in domestic waterfowl and live bird markets, leading to greater environmental contamination [61]. Recombinations of viruses in animals are a global concern. The H5N1 outbreak in Southeast Asia, H3N2 variant in the USA in 2012, and H7N9 avian cases in China 2013 are examples of such new threats. Effective surveillance is required to monitor such developments [62].

There is a growing danger that in the future avian influenza, a subtype of influenza A, may result in a worldwide pandemic. A/H5N1 exhibits several serious characteristics, such as increased virulence and human-to-human transmission in some cases, rather than bird-to-human transmission. The disease causes high morbidity and mortality due to pneumonia and respiratory failure [63].

H1N1 was first reported in Mexico and spread to the United States. The infection from a novel swine-origin influenza A (H1N1) virus rapidly spread to become a worldwide pandemic in 2009. Virus-associated hemophagocytic syndrome may play an important role in development of multiorgan failure and ensuing death in H1N1 infection [64].

SARS is a respiratory infection caused by a coronavirus, which appears to have jumped from animals to humans. The disease was first reported in China in 2003 and rapidly spread from to the rest of the world in a 1 year period. It resulted in more than 8000 patients in 29 countries causing 774 deaths [65].
