Although first cultured in human and monkey kidney cell cultures in 1954, the measles virus has been recognized as a clinical entity for centuries, dating as far back as 600 B. C. The very first scientific description of measles is credited to Persian physician Ibn Razi, who published a book entitled Kitab fi al-jadari wa-al-hasbah. Razi’s study of measles was significant because its attempt to definitively distinguish it from smallpox.
In the past century, measles has been estimated to have killed about 200 million people worldwide, and a significant gain was made in the battle against it when in 1963, an attenuated vaccine was made available to the public. Since that time the number of measles cases in the United States has dropped sharply. In less well-developed counties, however, the morbidity and mortality from measles infection remain at high levels.
Speaking geographically, measles does not vary much in incident areas between North America and areas outside of it. In 2005, almost all of confirmed measles cases were import-associated and 50% of all measles cases occurred among 5 to 19 years old children. After measles cases hit a record low in 2004, measles morbidity increased by 79%. This morbidity increase is attributed to an initial outbreak in Indiana, which originated from an unvaccinated U. S. resident who had acquired an infection while traveling in Romania.
Measles is an enveloped, spherical RNA virus belonging to Paramyxoviridae family and measures approximately 150 nanometers in diameter, measuring approximately 150 nm in diameter and contains hemagglutinin peplomers but unlike many other paramyxoviruses, it does not carry neuraminidase. The respiratory system is the means by which the measles virus is spread within the infected host, and as a highly contagious virus can be transmitted through respiratory secretions. As such, it passes from person to person via aerosol droplets that are expelled by coughing.
Once transmitted, the virus infects the epithelial cells of its new host, and can replicate in blood vessels, the central nervous system, the conjunctivae, the lymphatic system and/or the urinary tract. Humans are the only known hosts of measles. Diagnosis of measles relies on the identification of specific clinical features suchas Koplik’s spots and rush. This is however, not entirely reliable, as in many cases Koplik’s spots are not detected and the measles rash may be misdiagnosed.
In any case, upon infection the virus induces the formation of multinucleate giant cells about half a week to a week after the disappearance of the rash. Detection of these multinucleate giant cells is possible through the use of a technique known as indirect fluorescent antibodies, which is most effective on the nasopharyngeal cells. Also, complement-fixing, neutralizing, and hem agglutination-inhibiting antibodies develop in the serum at the rash and thus, the hem agglutination inhibition test is most useful in determining a patient’s immunity status.
There is however, no specific treatment or antiviral therapy for uncomplicated measles, but fortunately most patients with uncomplicated measles will recover with rest and supportive treatment. The best preventive means of addressing measles is vaccination and is permissible for anyone above 15 months of age. In the early 60s, an inactivated vaccine prepared from the cell cultures obtained from chick embryos was utilized and since then numerous refinements have been made to succeeding vaccines.
However, administering vaccines to those who have previously received inactivated vaccine does not always provide protection. It is believed that this is because the immune response generated by the inactivated vaccine interferes with that generated from live vaccine. Additionally, vaccines should not be administered to pregnant women or to anyone with a febrile illness. There is also the immune serum globulin (ISG) which provides short-term protection if given less than 6 days before exposure to the virus.
However, vaccines should not be given at the time of ISG administration. In 2006, the Council of State and Territorial Epidemiologists, approved a modifications to case classification for measles. This means that in the immediate future, the epidemiology of the United States will reflect global epidemiology, which will therefore recognize that measles is no longer endemic to the United States. This case classification modification will help define the impact of imported cases in U. S. by clearly identifying the origin of each case.