Emerging Infections

Newly Emerging Infections

Newly emerging infections are diseases that have not previously appeared in humans. One such disease is HIV/AIDS, which is believed to have made the leap from animals to humans between 60 and 70 years ago, possibly as a result of contact with infected chimpanzees. To date, human immunodeficiency virus (HIV), the virus that causes AIDS, has infected more than 60 million people worldwide, most living in developing countries, and 70% living in subSaharan Africa. With as much as 25% to 30% of the adult population infected, life expectancies have fallen dramatically in many of these countries. Since the appearance of the first recognized case in December 1981, more than 25 million have died of the disease, causing socioeconomic devastation in many populations. While antiretroviral drugs have been developed, there is no cure for the disease, and most of its victims have no access to the treatment.

Reemerging Infections

Reemerging infections are ones that have existed in the past but are undergoing a rapid resurgence in incidence or geographical and host range. Among the most deadly is the tuberculosis (TB). Recognized among humans as far back as 4000 BCE, it was an incurable disease that, in the 19th and early 20th centuries, struck especially hard at the urban poor population. It was not until 1906 that an immunizing agent was developed, and only in 1921 was it used successfully in humans. The development of the antibiotic streptomycin in 1946 provided a treatment for those already suffering from the disease, replacing sanatoria and often draconian surgical interventions.

With the availability of vaccine and treatment, many hoped that tuberculosis could finally be eradicated. However, in the 1980s, drug-resistant strains began to appear, aided in part by failure of patients to complete the full course of drugs. The resulting reemergence of the disease has led to the infection of as many as one third of the world's population. Factors such as the prevalence of HIV/AIDS make entire populations more susceptible to infection with TB. Of special concern is the emergence of multiple drugresistant strains of TB.

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