NEW BACTERIA DEPLETING FISH POPULATION IN CHESAPEAKE BAY
A new species of bacteria is the cause of a disease that is depleting the striped bass population in the Chesapeake Bay, say researchers at the University of Maryland College of Veterinary Medicine. They report their findings in the February 2001 issue of the Journal of Clinical Microbiology. In the early 1980s the Chesapeake Bay suffered a collapse of some of its fish stocks including the striped bass. Restrictions on fishing activity improved the fish populations in the early 1990s, but by the end of the decade there was again a noticeable decline in the striped bass population. After closely monitoring the health of the striped bass population, officials discovered that many of the fish suffered from systemic mycobacteriosis.
"This was the first time that mycobacteriosis had been detected in the Chesapeake Bay and represents the first reported case of mycobacteriosis in wild fish on the Atlantic coast," say the researchers, who have isolated the bacterium responsible and suggest that it is a new species of mycobacterium, the family of bacteria that is also responsible for tuberculosis in humans.
In fish, mycobacteriosis is a chronic, progressive disease and may take years to develop. Affected fish may lose their appetite and have impaired growth. In some cases skin lesions in the form of blisters or ulcers may develop. Although mycobacteriosis is an old disease and exists worldwide, there have been very few reports of its occurrence in the wild and very little is known about its prevalence and impact on wild fisheries.
"With the knowledge of the unique sequences in this new isolate, PCR assays can be designed for the specific identification of this isolate of Mycobacterium," say the researchers. This will enable investigation of future outbreaks as well as epidemiological studies to determine reservoirs of infection and possible routes of transmission.
(R.A. Heckert, S. Elankumaran, A. Milani and A. Baya. 2001. Detection of a new Mycobacterium species in wild striped bass in the Chesapeake Bay. Journal of Clinical Microbiology, 39: 710-715.)
BORNAVIRUS NOT LINKED TO PSYCHOSIS
A recent study in Japan suggests that despite recent research suggesting a link between Borna disease virus infection and some psychiatric disorders, the virus may not be responsible after all. The results of the study appear in the February 2001 issue of the Journal of Clinical Microbiology.
Borna disease virus (BDV) affects the central nervous system and can infect a variety of animals including humans. The appearance of sometimes severe behavior disturbances in animals infected with BDV and preliminary studies on patients with schizophrenia have suggested that BDV may play a role in human psychiatric disorders.
In the study, the researchers compared the prevalence of BDV in patients with mood disorders and schizophrenia with healthy blood donors in Japan. They found a relatively low incidence (less than 10 percent) of the virus in all groups.
"Previous seroepidemiological studies by Western blot analysis have suggested a possible association between BDV infection and human psychiatric diseases with a higher prevalence of BDV antibodies in psychiatraic patients, ranging from 12 to 38 percent. However, our results did not support these previous reports."
Despite their results, the researchers still believe that some psychiatric disorders may be associated with BDV infection and suggest that further studies with a larger number of subjects may be necessary.
(K. Fukuda, K. Takahashi, Y. Iwata, N. Mori, K. Gonda, T. Ogawa, K Osonoe, M. Sato, S.-I. Ogata, T. Horimoto, T. Sawada, M. Tashiro, K. Yamaguchi, S.-I. Niwa, and S. Shigeta. 2001. Immunological and PCR analyses for Borna disease virus in psychiatric patients and blood donors in Japan. Journal of Clinical Microbiology, 39: 419-429.)
FIGHTING CAMPYLOBACTER WITH CAMPYLOBACTER
In the battle against foodborne disease it may make sense to fight fire with fire. Researchers at the USDA Agricultural Research Service in Athens, Georgia suggest one way to fight Campylobacter bacteria contamination of chickens is with Campylobacter itself. They report their results in the February 2001 issue of the journal Applied and Environmental Microbiology. The researchers have discovered that infecting baby chicks with a chicken-specific (one that does not cause disease in humans) strain of the bacterium Campylobacter jejuni just days after hatching results in the animals becoming colonized with that strain, crowding out any strains potentially harmful to humans.
"Our results suggest that it is possible to use combinations of C. jejuni chicken isolates as a defined bacterial preparation for the competitive exclusion of human-pathogenic C. jejuni in poultry," say the researchers.
Campylobacter jejuni is one of the most common causes of bacterial gastroenteritis in the United States and poultry consumption is a significant risk factor.
H.-C. Chen and N.J. Stern. 2001. Competitive exclusion of heterologous Campylobacter spp. in chicks. Applied and Environmental Microbiology, 67: 848-851.)
Copies of the following journal articles can be accessed online at http://www.asmusa.org/pcsrc/tip.htm
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.