Excerpt from Polymicrobial Diseases
Chapter 19 – Virus-induced Immunosuppression
http://www.ncbi.nlm.nih.gov
“MV infection produces an immune system paradox. MV infection, while inducing lifelong immunity, also suppresses the immune system leading to an increase in susceptibility to other, secondary infections (24, 67, 91). In vitro research has shown that MV infection of cell cultures makes the cells more susceptible to a secondary bacterial invasion (13). The immune suppression appears coincident with the marked activation of the immune system, in the form of MV-specific responses, which in turn is coincident with the onset of clinical disease, i.e., rash. Immune suppression can continue for many weeks after the apparent recovery from measles (47). Therefore, MV infection results in both immune activation and immune suppression at the same time. Immune suppression is apparent in vivo in such forms as the loss of the DTH skin test response, the impairment of the production of antibody and cellular immune responses to new antigens, reactivity of tuberculosis, and remission of immune mediated diseases such as juvenile rheumatoid arthritis (15, 16, 84, 95). Immune suppression is apparent in vitro in such forms as suppressed lymphoproliferative responses to mitogens, abnormal lymphokine production, and inhibition of antigen-specific proliferation of T lymphocytes (9, 40, 87).
Secondary bacterial, protozoal, or viral infections occur because of immunosuppression by MV infection. These infections can result in pneumonia, chronic pulmonary disease, otitis media, laryngotracheobronchitis, adult respiratory distress syndrome, hepatitis and diarrhea (7, 29). Secondary infections are more common in underdeveloped countries. These secondary infections account for most of the morbidity and mortality associated with acute measles (7). Much research has been done to determine whether a correlation exists between malnutrition and/or overcrowding, which in turn results in a more intensive exposure to measles, and measles mortality (1, 2, 4, 5, 28). A natural epidemic of measles virus in a rhesus monkey colony showed that enteric organisms normally carried in healthy individuals became serious pathogens during the viral infection (58). Some of the bacteria that can be involved in superinfections in measles patients are Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Morganella morganii, Pseudomonas aeruginosa, Chlamydia trachomatis, and Streptococcus pyogenes (7, 56, 94). Some of the viruses that can be involved in superinfections include adenovirus and herpes simplex virus (7, 88, 92). Although acute measles infection causes a relatively high mortality, there was no increase in mortality of those who survived a measles infection found in the postmeasles period as compared with uninfected community controls (6).”