Why infectious disease

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Clinical Trials. Article: Yee-Sin Leo: a leader in Singapore's fight against infectious diseases. Article: Serum leptin level as a diagnostic and prognostic marker in infectious Infectious Diseases -- see more articles. Find an Expert. When a new version of the influenza virus arises that has either never circulated in the human population or has not circulated for a very long time so that most people do not have immunity against the virus , a pandemic can occur.

The H5N1 virus caused concern because it was so deadly more than half of the cases were fatal , but it did not spread easily from person to person. Additional novel versions will continue to emerge.

The greatest danger would come from a version of the flu virus that is very deadly but is also transmitted readily from one individual to another. Despite significant advances in infectious disease research and treatment, the control and eradication of these diseases faces major challenges. A WHO report released in warns that infectious diseases are spreading more rapidly than ever before and that new infectious diseases are being discovered at a higher rate than at any time in history.

In just the past five years, the WHO has identified over epidemics of infectious diseases including avian flu, swine flu, polio, and cholera.

With greatly increased human mobility, infectious diseases have the potential to swiftly become global epidemics and pandemics. The sections on Emerging Infectious Diseases and Bioterrorism Agents further explore these challenges. Learn more about some of the technical terms found on this page by visiting our glossary of terms.

Department of Molecular Virology and Microbiology. Media Component. Influenza Historically, there have been about three to four influenza pandemics each century. Many organisms live in and on our bodies. They're normally harmless or even helpful. But under certain conditions, some organisms may cause disease. Some infectious diseases can be passed from person to person. Some are transmitted by insects or other animals.

And you may get others by consuming contaminated food or water or being exposed to organisms in the environment. Signs and symptoms vary depending on the organism causing the infection, but often include fever and fatigue. Mild infections may respond to rest and home remedies, while some life-threatening infections may need hospitalization. Many infectious diseases, such as measles and chickenpox, can be prevented by vaccines.

Frequent and thorough hand-washing also helps protect you from most infectious diseases. Each infectious disease has its own specific signs and symptoms. General signs and symptoms common to a number of infectious diseases include:. An easy way to catch most infectious diseases is by coming in contact with a person or an animal with the infection. Infectious diseases can be spread through direct contact such as:. Person to person. Infectious diseases commonly spread through the direct transfer of bacteria, viruses or other germs from one person to another.

This can happen when an individual with the bacterium or virus touches, kisses, or coughs or sneezes on someone who isn't infected. These germs can also spread through the exchange of body fluids from sexual contact. The person who passes the germ may have no symptoms of the disease, but may simply be a carrier. Disease-causing organisms also can be passed by indirect contact.

Many germs can linger on an inanimate object, such as a tabletop, doorknob or faucet handle. Limitations of current expertise were illustrated with influenza A H1N1 swine flu, as the standard concept based on historic precedent is that new influenza epidemics come from Asia in the wintertime, but this one came in the eastern hemisphere in the summertime [ 27 ].

Both show high mortality rates, but little evidence so far of that single critical mutation permitting attachment to the hemagglutinin antigen to permit sustained person-to-person transmission [ 26 ]. Middle East respiratory syndrome MERS coronavirus: This coronavirus is a major global concern with analogies to the SARS coronavirus in terms of its perceived potential to become a global epidemic with high mortality and no apparent treatment [ 31 , 32 ]. Of immediate importance in the United States is recognition of risk with appropriate diagnostic testing, isolation, and management of persons with severe, unexplained pneumonia associated with recent travel to the Arabian Peninsula MERS [ 32 ].

Foodborne disease: Widespread foodborne epidemics are now a common consequence of the massive food distribution system that permits contaminated beef or lettuce from Mexico to reach stomachs in distant multistate areas, with medical consequences involving hundreds or thousands of people. This includes the more recent emergence of the GII.

These outbreaks seem likely to continue, with unpredictable pathogens in unpredictable places [ 33—35 ]. Heartland virus: A recently encountered tick-borne disease in Tennessee and Missouri with 10 cases and 2 deaths [ 36 ]. Polio-like virus infection with extremity paralysis has been recently reported in 5 and possibly 25 children in California [ 37 ].

Ebola virus: WHO has reported an outbreak in Guinea involving a new clade of this usually fatal infection [ 38 ]. This listing could continue almost indefinitely. The point is that epidemics are the domain of infectious diseases and public health, with the expectation for management or prevention of outbreaks with requirements for detection, reporting, isolation, and case management.

The listing here includes diverse pathogens, some life-threatening diseases, infections with important public health implications, an upsurge of pediatric infections in adults, many travel-related infections, multiple public health threats, and the continuous concerns for influenza and foodborne disease. The major weaponry of the infectious disease catalog includes antibiotics, vaccines, and public health.

These categories are remedial reading, but some facets are worthy of emphasis. The value of antibiotics seems obvious. She received penicillin intravenously starting 14 March , promptly recovered, and survived to age 90 years [ 39 ]. The more recent experience with bacterial resistance and sparse pipeline threatens this miracle, but antiviral development is quite different, primarily for HIV and hepatitis C virus HCV. It now appears that patients with HIV can achieve near-normal longevity [ 41 ].

HCV infection is even more impressive in terms of speed of progress and ability to cure. The HCV treatment story reflects the efficiency of basic science to define targets, pharmaceutical skills of industry, well-organized trial networks, and a regulatory agency US Food and Drug Administration [FDA] that facilitated product development [ 42 ].

The impact of vaccines is also impressive. A recent report concluded that the global total for lives saved by vaccines exceeds million [ 43 ]. The impact could be substantially greater with more global access, fewer refusals, and a better pertussis vaccine.

This illustrates the challenge and the priorities [ 44 ]. The epidemic was finally halted, but the toll was 18 cases and 6 fatalities over 6 months [ 45 , 46 ].

Another KPC epidemiologic investigation showed widespread distribution of this microbe from a long-term acute-care facility in the Chicago area [ 47 ], and others have demonstrated distribution of KPC by air travel from India to Europe [ 48 ].

There is no specialty field in medicine that demonstrates shifting priorities like infectious diseases. Note that the year interval resulted in a completely new agenda for what was considered timely and important in the field based on rapid changes in topical microbes, new epidemics, and new diagnostics, but not new antimicrobials.

It is impossible to predict the menu for It is now known that genes for resistance to antimicrobial agents were well established in bacteria at least 3 million years before evidence of human life [ 49 ]. The use of antibiotics has selected for these genes by Mendelian laws, making it increasingly difficult to control previously treatable infections. The microbes are educated to resist penicillin and a host of penicillin-fast organisms is bred out which can be passed to another individual and perhaps from there to others until they reach someone who gets a septicemia or a pneumonia which penicillin cannot save.

In such a case, the thoughtless person playing with penicillin treatment is morally responsible for the death of the man who finally succumbs to an infection with penicillin-resistant organisms. It now appears that Fleming's prediction is a harsh reality and evolutionary microbial resistance genes are gaining the upper hand, reflecting the combination of massive antibiotic use and lack of new pharmacologic agents.

A disturbing observation in the United States is the conspicuous absence of a national plan to deal with resistance, including the lack of a living record of antibiotic consumption and resistance correlated by location and trajectory. This is in sharp contrast to the European Union, which includes 28 countries with 24 official languages and diverse cultures, but has systematically collected data on antibiotic consumption and microbial resistance patterns for 15 years [ 52 , 53 ].

This has resulted in multiple publications with data reviews, studies of interventions, messages to consumers such as an eBug Internet program for students, a European Antibiotic Awareness Day, standardized methods to collect data [ 54 ] and a recent point plan with budget to address the issue [ 55 ]. Their data are striking in showing the dramatic association between per capita antibiotic use and national resistance patterns. For example, antibiotic consumption in Greece is nearly 4 times that of the Netherlands, so we expect more resistance problems in Greece, but the magnitude of this difference is alarming: Bacteremic carbapenemase strains among all bacteremic K.

The European Union appears to have a mature and substantive model to learn from, with the important caveat that it functions well because there is no claimed ownership, as there are 28 equal partners. There are also some good national programs that have successfully addressed specific problems to learn from:. EU data for showed that France had embarrassingly high antibiotic use rates, accompanied by increasing resistance by S.

This prompted a national campaign targeting prescribers and consumers on antibiotic abuse and its consequences. A recent report from Israel showed a national campaign to reduce the incidence of KPC. Analysis of their results with a prevention bundle showed a reduction from 55 per patient-days to 4. The 3 examples given are based on national data addressing major challenges with impressive results. In the United States, this remains a unanswered challenge, but is also an opportunity for the skills of the infectious disease discipline in terms of data collection, evaluation, interventional trials, and policy implementation into practice, primarily in the form of antibiotic stewardship.

Recent reports using gene sequencing suggest that conventional methods of infection control could substantially improve this effort. Examples: 1 Results from the United Kingdom have largely disproven conventional teaching regarding the epidemiology of C. It seems clear that as this technology gets faster and cheaper, it will be embraced as an infection control standard [ 61 ], although there needs to be caution and skill in interpreting results [ 62 ].

Some of this is direct patient care, but possibly very attractive targets for impact are the development and implementation of innovative programs that deal with the vast need combined with minimal resources [ 63 ]. The new healthcare system should value infectious disease expertise based on its important role in addressing resistance and costs associated with nosocomial infections. Nevertheless, it is feared that the current structure and payment system are not constructed as a good fit to prioritize infectious disease skills.

Specifically, there is no code for preventing infections, conserving antibiotic use, or preventing resistant pathogens. This might be an erroneous conclusion, or the situation may change as the system matures and becomes serious about addressing the crisis.