Microbiology and Immunology

Seroconversion WORLD OF MICROBIOLOGY AND IMMUNOLOGY

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through came when his fellow physician, Jakob Kolletschka

(1803–1847), died of blood poisoning after cutting his finger

while performing an autopsy. Semmelweis noticed that the

pathological features of the autopsy on Kolletschka’s body

matched those of the autopsies of the puerperal fever victims.

Semmelweis then only suspected, and did not prove, that the

fever was a septicemia, an intrusion of microorganismsfrom

a local infection into the bloodstream, but he instantly took

action. In May 1847, he ordered all personnel under his

authority to wash their hands between patients. This was a

novel, radical, and unpopular rule, but in just a month the

maternal death rate at the Vienna General Hospital dropped

from twelve to two percent.

Even though Semmelweis had solid results and statistics

on his side, many physicians simply refused to believe that

washing their hands, which they considered undignified, could

save lives. Resistance to his rule stiffened. Semmelweis made

many powerful enemies, and in March 1849, he was demoted

from his supervisory role. He served at St. Rochus Hospital in

Pest from 1851 to 1857, but never achieved his former profes-

sional status.

Holmes was facing a similar crisis in America. In 1843,

Holmes first claimed in print that puerperal fever was conta-

gious. Semmelweis first published his findings in 1848. Now

having heard of Semmelweis, Holmes in 1855, expanded his

original article into a small book that explicitly praised

Semmelweis. Likewise, having now heard of Holmes,

Semmelweis published Die Aetiologie, der Begriff, und die

Prophylaxis des Kindbettfiebers[The Etiology, Concept, and

Prophylaxis of Childbed Fever] in 1861. The book was not

well received. Semmelweis was a poor prose stylist, and his

lack of writing skill adversely affected his campaign. Holmes,

on the other hand, an accomplished essayist and poet as well

as a first-rate physician, proved more persuasive, although it

would still be thirty years before sanitary and hygienic meth-

ods became standard in American and European hospitals.

While no one ridiculed Holmes, who had enough charm

and grace to forestall such attacks, Semmelweis became sub-

ject of mockery in the central European medical community.

In 1863, the frustration he had long felt finally took its toll on

his spirit. He became chronically depressed, unpredictably

angry, socially withdrawn, and increasingly bitter. In July

1865, a coalition of colleagues, friends, and relatives commit-

ted him to the Niederösterreichische Heil-und Pflegeanstalt,

an insane asylum in Döbling, near Vienna. He died there a

month later, on August 13, 1865, from bacteremia due to an

infected cut on his finger, with symptoms markedly akin to

those of puerperal fever.

See alsoBacteria and bacterial infection; Contamination, bac-

terial and viral; Germ theory of disease; Hygiene; Infection

control; Streptococci and streptococcal infections;

Transmission of pathogens; Viruses and responses to viral

infection

SERILITY•seeREPRODUCTIVE IMMUNOLOGY

SSeroconversionEROCONVERSION

Seroconversion is a term that refers to the development in the

blood of antibodies to an infectious organism or agent.

Typically, seroconversion is associated with infections caused

by bacteria, viruses, and protozoans. But seroconversion also

occurs after the deliberate inoculation with an antigenin the

process of vaccination. In the case of infections, the develop-

ment of detectable levels of antibodies can occur quickly, in

the case of an active infection, or can be prolonged, in the case

of a latent infection. Seroconversion typically heralds the

development of the symptoms of the particular infection.

The phenomenon of seroconversion can be important in

diagnosing infections that are caused by latent viruses.

Examples of viruses include hepatitisB and C viruses, the

Epstein Barr virus, and the Human Immunodeficiency Virus

(HIV). When these viruses first infect people, the viral nucleic

acid can become incorporated into the genome of the host. As

a result, there will not be an immune response mounted

against the virus. However, once viral replication has com-

menced antibodies to viral proteins can accumulate to

detectable levels in the serum.

Seroconversion is am important aspect of Acquired

ImmunodeficiencySyndrome (AIDS). Antibodies to HIV can

sometimes be detected shortly after infection with the virus,

and before the virus becomes latent. Symptoms of infection at

this stage are similar to the flu, and disappear quickly, so treat-

ment is often not sought. If, however, diagnosis is made at this

stage, based on presence of HIV antibodies, then treatment can

begin immediately. This can be important to the future outlook

of the patient, because often at this stage of the infection the

immune systemis relatively undamaged. If seroconversion

occurs following activation of the latent virus, then immune

destruction may already be advanced.

The presence of antibodies in the serum occurs much

earlier in the case of infections that occur very soon after the

introduction of the infectious microorganism. The type of anti-

bodypresent can be used in the diagnosis of the infection.

Additionally, seroconversion in the presence of symptoms but

in the absence of detectable microorganisms(particularly bac-

teria) can be a hallmark of a chronic infection caused by the

adherent bacterial populations known as biofilms. Again, the

nature of the antibodies can help alert a physician to the pres-

ence of a hitherto undetected bacterial infection, and treatment

can be started.

See alsoAntibiotic resistance, tests for; Antibody and antigen;

Antibody-antigen, biochemical and molecular reactions;

Antibody formation and kinetics; Immunity, active, passive

and delayed; Immunochemistry; Immunodeficiency disease

syndromes; Serology

SSerologyEROLOGY

Serology is the study of antigen-antibody reactions outside of

a living organism (i.e., in vitro, in a laboratory setting). The

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