HMPV in Immunocompromised Patients: Frequency and Severity in Pediatric Oncology Patients

Abstract

Cancer is the first cause of death by disease in childhood globally. The most frequent types of cancers in children and adolescents are leukemias, followed by brain and central nervous system tumors and lymphomas. The recovery rate of cancer in children is around 80% in developed countries and up to 30% in developing countries. Some of the main causes of complications in children and adolescents with cancer are respiratory viral infections, mainly in bone marrow-transplanted patients. Respiratory viruses have been detected in the bronchoalveolar lavage or nasal wash specimens from cancer patients with or without respiratory illness symptoms. Human metapneumovirus (HMPV) is within the ten most common viruses that are encountered in samples from pediatric patients with underlying oncology conditions. In most of cases, HMPV is found as the only viral agent, but co-infection with other viruses or with bacterial agents has also been reported. The discrepancies between the most prevalent viral agents may be due to the different populations studied or the range of viral agents tested. Some of the cases of infection with HMPV in cancer patients have been fatal, especially in those who have received a hematopoietic stem cell transplant. This review seeks to show a general view of the participation of HMPV in respiratory illness as a complication of cancer in childhood and adolescence. Keywords: pediatric cancer infections; HMPV; fatal cases in HSCT patients Childhood Cancer Global SituationCancer is the first cause of death by disease in children around the world. The five-year rate of survival of children who have cancer is up to 80% in developed countries, but for developing countries, the survival rate is less than 30% [1].According to a study based in cancer registries from 52 countries, the types of cancer in childhood (0-19 years old) during 2001-2010 were leukemia, lymphoma, central nervous system tumors, sympathetic nervous system tumors, retinoblastoma, renal tumors, hepatic tumors, bone tumors, soft tissue sarcomas, germ cell and gonadal tumors, epithelial tumors, and melanomas. The most frequent cancers in children of 0-14 years are leukemia, followed by lymphoma; meanwhile, for the ages of 15-19, the most prevalent is lymphoma, followed by leukemia [2].Cancer in childhood comprises only 1% of the total cancer cases worldwide; however, it has a dramatic impact. Recently the years of life lost due to cancer in childhood (0-19 years old) were calculated with global cancer registries in 2017, with a result of more than 11 million years [3].

Viral Respiratory Infections in Hematological Patients

“…Human metapneumovirus is a major cause of infection in children worldwide [37]. Since it was discovered, several international studies have highlighted how primary infection occurs before 5 years of age and that all children are potentially infected at 10 years of life.…”

“…Another more recent review highlighted that 7% of all children with cancer who developed a respiratory infection were positive for hMPV. Of this 7%, about 1% died; 2.3% of pediatric patients who received a transplant and were hMPV positive died as well [37].…”

Respiratory Viral Pathogens in Solid Organ and Hematopoietic Stem Cell Transplant Recipients

“…Mortality rates at 100 days in some studies have been high (reported as high as 43%), and mortality has been associated with steroid therapy, oxygen requirement >2 L, or mechanical ventilation, and bone marrow as stem cell source [137]. Reports also suggest higher attack rates in pediatric and adolescent HSCT populations [138].…”

Human Metapneumovirus (hMPV) Infection and MPV467 Treatment in Immunocompromised Cotton Rats Sigmodon hispidus

“…Children younger than 6 months of age are about three times more likely to be hospitalized because of hMPV infection than children from 6 months to 5 years [ 6 ]. Other susceptible populations include children with underlying high-risk conditions [ 6 ], the elderly [ 7 ], and immunocompromised individuals [ 8 , 9 ].…”