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Submodule 9: Social Impacts
Impacts on Human Health and Public Health Concerns
Pathogens
Collecting birds to test for bird flu (photo courtesy State
Department)
Many of the most feared human diseases are invasive species, including smallpox, HIV/AIDS, and “bird flu.” In the U.S., human and monetary cost from non-indigenous diseases has been especially high for influenza and AIDS. Other significant non-indigenous diseases include syphilis and cholera. In the U.S., there are currently about 53,000 cases of syphilis reported each year, and the cost just to treat newborn children (who contract the disease from infected mothers) was estimated to be over $18 million. The CDC (Centers for Disease Control) reports that about 36,000 Americans die from influenza and related secondary infections each year.
Emerging diseases sporadically appear as outbreaks at locations around the world. Two such diseases, SARS (Severe Acute Respiratory Syndrome) and Ebola (a type of hemorrhagic fever of the Filoviridae family) have, fortunately, not yet reached the U.S. Several of these diseases are animal-borne, which when mutated can become capable of infecting humans. This is the case with “bird flu”, which is normally found only in birds. The overriding concern is for a subtype of bird flu called Influenza A (H5N1) virus. This virus is commonly found in birds, but it has also been responsible for infecting humans who have no natural immunity to the virus. For this reason, an epidemic (local outbreaks), or even a pandemic (worldwide outbreak) of epic proportions is possible if H5N1 mutates into a virus that is easily transmissible from person to person. To make matters worse, human infections can be particularly deadly as a result of secondary pneumonia and organ failure. Most viruses have a high mutation rate which is why, for example, “flu” shots need to be administered annually – human influenza viruses rapidly mutate, too.
Smallpox virus (photo
courtesy CDC)
Smallpox (variola), an especially deadly viral infection once found around the world, is commonly thought to have originated in Africa and then spread to India and China, although there is some evidence that it first existed in the Middle East over 10,000 years ago. Throughout written human history there is mention of the disease with the first epidemic reported in 1350 BCE during the Egyptian-Hittite war. Between the 5th and 7th centuries CE smallpox reached Europe and was prevalent in major European cities by the 1700s. European explorers brought it to the New World, wiping out many native populations who had never been exposed to the disease. It was the fact that those who had the disease did not become infected a second time that lead to, thus far, the only successful virus eradication in history and vaccinations. Currently, the only viable virus exists in research labs; it is feared as a potential biological weapon.
Non-indigenous diseases also inflict a high monetary cost. A 1999 report stated that they cost the U.S. economy about $6.5 billion. In 2000, it was reported that the cost of treating AIDS patients in the U.S. was reported as between $7 and $8 billion. On a year-to-year basis, influenza costs are estimated to be $4.6 billion for patient care plus an additional $7 billion for lost work and productivity.
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