Phosphatase activity in avian mycoplasmas.

Fifty-four strains of avian mycoplasma representing 11 species or serotypes were examined for their phosphatase activity using two different methods. Both methods gave similar results. All of four strains of Mycoplasma anatis and six of M meleagridis and the type strain of serotype L were phosphatase positive. The other species gave variable reactions between strains and on different occasions of testing.     

Demonstration in live chickens of the carrier state in infectious laryngotracheitis

Two separate groups of nine-week-old specific pathogen free cockerels maintained in isolation were infected with a field strain of infectious laryngotracheitis (ILT) virus, either by intratracheal or combined intranasal and supraconjunctival inoculation. Birds were monitored for virus shedding from five sites on alternate days during the acute phase and three times weekly until week 17. They were then treated with cyclophosphamide on three consecutive days and thereafter swabbed daily. During the acute phase clinical signs were observed and virus was recovered from ocular and nasal sites for up to six to eight days. Initially after the acute phase no virus could be detected. However, from the seventh week after infection intermittent, apparently spontaneous shedding was detected in four of five birds in each group. There was no clear effect of cyclophosphamide treatment on re-excretion patterns, possibly because of the high levels of virus shedding already occurring. Thus, a carrier state for ILT virus has been demonstrated experimentally in live clinically recovered birds.     

Bacterial Diseases of Cassava

Abstract

Recent developments on the identities of the causal agents of bacterial diseases of cassava throughout the world are discussed.     

Enterovirulence of enterotoxigenic Bacteroides fragilis in gnotobiotic pigs.

A porcine isolate of enterotoxigenic Bacteroides fragilis colonized the intestinal tract and caused watery, nonhemorrhagic diarrhea when given orally to 12, 1- to 2-day-old gnotobiotic pigs. Diarrhea occurred 2 to 3 days post-inoculation and continued throughout the 4 to 6 day post-inoculation period. Diarrheic pigs became mildly anorexic and dehydrated. They developed intestinal lesions characterized by swelling, vacuolation, and exfoliation of enterocytes, and crypt hyperplasia throughout the large intestine and, to a lesser extent, in the distal small intestine. Bacterial adherence to, or invasion of, the intestinal mucosa was not detected. A porcine isolate of nonenterotoxigenic B. fragilis was administered orally to six control pigs. The isolate colonized the intestinal tract, but the pigs did not develop clinical disease or intestinal lesions. The pathogenetic mechanism of the disease may involve mediation by a soluble enterotoxin (or toxins) elaborated by B. fragilis.     

Coral reefs under rapid climate change and ocean acidification

Atmospheric carbon dioxide concentration is expected to exceed 500 parts per million and global temperatures to rise by at least 2 degrees C by 2050 to 2100, values that significantly exceed those of at least the past 420,000 years during which most extant marine organisms evolved. Under conditions expected in the 21st century, global warming and ocean acidification will compromise carbonate accretion, with corals becoming increasingly rare on reef systems. The result will be less diverse reef communities and carbonate reef structures that fail to be maintained. Climate change also exacerbates local stresses from declining water quality and overexploitation of key species, driving reefs increasingly toward the tipping point for functional collapse. This review presents future scenarios for coral reefs that predict increasingly serious consequences for reef-associated fisheries, tourism, coastal protection, and people. As the International Year of the Reef 2008 begins, scaled-up management intervention and decisive action on global emissions are required if the loss of coral-dominated ecosystems is to be avoided.     

Survey of field outbreaks of avian infectious laryngotracheitis in England and Wales.

Field outbreaks of infectious laryngotracheitis in commercial chicken flocks in England and Wales between 1985 and 1988 were investigated. Material from 49 outbreaks was submitted to Liverpool University, and virus was isolated from 17 of them. The results of a questionnaire on each outbreak are described. Generally, the disease was of moderate severity, and mainly affected laying flocks; it occurred in birds of a wide age range but most of the outbreaks were in birds between 10 and 20 weeks of age. The disease was not seen more frequently at any particular time of the year, and there was no evidence of a common source of infection. Three of the affected flocks had recently been moved and were beginning to lay; these stresses may have caused the re-excretion of latent virus.     

Cost-benefit analysis and investment appraisal in relation to pest control measures

A distinction is drawn between cost-benefit analysis and investment appraisal. Both are methods for evaluating projects, with cost-benefit analysis looking at proposals from the angle of the larger community in contrast to investment appraisal which looks at them from the individual, or firm, point of view. The time value of money is examined and also the treatment by cost-benefit analysis of social values and other elements outside the purview of investment appraisal, the so-called externalities or spillovers. Cost-benefit analysis of pest control measures is shown to depend heavily on analysis of the complexities and interactions of the biological/biochemical systems involved. This leads to the conclusion that the main thrust of cost-benefit studies in the pesticide field is to improve our understanding of pest problems and thereby to improve the efficiency of pest control measures, to the benefit of both the industry and the public.