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Emerging or re-emerging bacterial diseases are shown on a world map. Multidrug-resistant tuberculosis is emerging in North America, Europe, and Asia. Vancomycin-resistant Staphylococcus aureus and E. coli O157:H7 are emerging in North America and East Asia. Lyme disease is spreading in North America. Cholera is emerging in Africa and South America. Diptheria and typhoid fever are re-emerging in Asia.
The map shows regions where bacterial diseases are emerging or reemerging. (credit: modification of work by NIH)

Some of the present emerging diseases are not actually new, but are diseases that were catastrophic in the past ( [link] ). They devastated populations and became dormant for a while, just to come back, sometimes more virulent than before, as was the case with bubonic plague. Other diseases, like tuberculosis, were never eradicated but were under control in some regions of the world until coming back, mostly in urban centers with high concentrations of immunocompromised people. The WHO has identified certain diseases whose worldwide re-emergence should be monitored. Among these are two viral diseases (dengue fever and yellow fever), and three bacterial diseases (diphtheria, cholera, and bubonic plague). The war against infectious diseases has no foreseeable end.

Part A shows the red, bullseye-shaped rash of a person infected with Borrelia. Part B shows a micrograph of Borrelia, which look like tiny corkscrews. Part C shows the life cycle of the bacteria, which begins when Borrelia infect a tick egg. The egg hatches into larva, which feeds on a mouse, then into a nymph, which also feeds on a mouse. The nymph feeds again, this time on a deer, or sometimes a human.
Lyme disease often, but not always, results in (a) a characteristic bullseye rash. The disease is caused by a (b) Gram-negative spirochete bacterium of the genus Borrelia . The bacteria (c) infect ticks, which in turns infect mice. Deer are the preferred secondary host, but the ticks also may feed on humans. Untreated, the disease causes chronic disorders in the nervous system, eyes, joints, and heart. The disease is named after Lyme, Connecticut, where an outbreak occurred in 1995 and has subsequently spread. The disease is not new, however. Genetic evidence suggests that Ötzi the Iceman, a 5,300-year-old mummy found in the Alps, was infected with Borrelia . (credit a: James Gathany, CDC; credit b: CDC; scale-bar data from Matt Russell)

Biofilms and disease

Recall that biofilms are microbial communities that are very difficult to destroy. They are responsible for diseases such as infections in patients with cystic fibrosis, Legionnaires’ disease, and otitis media. They produce dental plaque and colonize catheters, prostheses, transcutaneous and orthopedic devices, contact lenses, and internal devices such as pacemakers. They also form in open wounds and burned tissue. In healthcare environments, biofilms grow on hemodialysis machines, mechanical ventilators, shunts, and other medical equipment. In fact, 65 percent of all infections acquired in the hospital (nosocomial infections) are attributed to biofilms. Biofilms are also related to diseases contracted from food because they colonize the surfaces of vegetable leaves and meat, as well as food-processing equipment that isn’t adequately cleaned.

Biofilm infections develop gradually; sometimes, they do not cause symptoms immediately. They are rarely resolved by host defense mechanisms. Once an infection by a biofilm is established, it is very difficult to eradicate, because biofilms tend to be resistant to most of the methods used to control microbial growth, including antibiotics. Biofilms respond poorly or only temporarily to antibiotics; it has been said that they can resist up to 1,000 times the antibiotic concentrations used to kill the same bacteria when they are free-living or planktonic. An antibiotic dose that large would harm the patient; therefore, scientists are working on new ways to get rid of biofilms.

Questions & Answers

how the kidney functions as osmoregulatory organ
Sam Reply
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Banda
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Ibrahim Reply
Simple term of science
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gopal
it's means what do u know about biology?
Phathu
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Melysa
the action of making a person immune to infections ,for immunisation
Kalia
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Phathu Reply
biology is the study of living organisms, divided into many specialized fields that cover their morphology, physiology, anatomy, behavior, origin, and distribution.
Julia
The study of all aspects of life. The study of all living organisms (such as animal cells and plant cells) in greater detail (their structure and how they function). It's a very broad science.
juanita
what is prokaryotic
Bhaskar Reply
what is pathogens
Bhaskar
transistion metals....
Wasik Reply
Why study ecology
Amos Reply
What name is given to group 8metals on a periodic table
Amos
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Elia Reply
Is the gradual change of something it can be either organisms
Amos
which of the following statements about the moss life cycle is false?
Israel Reply
posterior lobe of pitutary contains what?
MR Reply
What if vincristine and colchicibe disrupt mitosis by binding to tubulin
Rohith Reply
A plant in the understory of a forest displays a segmented stem and slender leaves arranged in a whorl. It is probably....
Israel Reply
How did the development of a vascular system contribute to the increase in size of plants?
Israel
If a flower lacked a megasporangium and microsporangium, what type of gametes would not form?
Israel
Seed plants are.. A. all homosporous B. mostly homosporous with some heterosporous C. mostly heterosporous with some homosporous D. all heterosporous
Israel
Besides the seed, what other major structure diminishes a plant's reliance on water for reproduction?
Israel
what role did the adaptations of seed and pollen play in the development and expansion of seed plants?
Israel
Some cycads are considered endangered species and their trade is severely restricted. Customs officials stop suspected smugglers who claim that the plants in their possession are palm trees, not cycads. How would a botanist distinguish between the two types of plants?
Israel
What are the two structures that allow angiosperms to be the dominant form of plant life in most terrestrial ecosystems?
Israel
how are carbohydrates,proteins and fats formed from triose phosphate
fonyuy Reply
Why does the actin filament only move in one direction? Describe in great detail.
Lashonda Reply
Two events happen when calcium binds to troponin.
Lashonda
which of the following statements about plant division is false?
Israel Reply
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esther

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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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