Suchergebnisse

The age-structures of rabbit populations at 4 climatically different sites in South Australia were found to have altered significantly since the introduction of Spilopsyllus cuniculi (Dale) as a vector of myxomatosis. The ratio of young of the year to older rabbits in summer was greatly reduced. There was evidence of decreases in size of all observed populations and (for 1 population) in ability to increase rapidly in favourable years. The ratio of young of the year to older rabbits was a convenient and sensitive index of changes in population structure; for analytical purposes, the log transformation (ln [ratio] or ln [ratio + 1]) was biologically and statistically sound. Since the fleas became established, field-strain viruses may have become more virulent and morbidity rates may have increased, but the factors enabling rabbit fleas to enhance myxomatosis as a cause of mortality are unknown. The apparent virulence may have increased because of selection for viruses of high virulence, which are best suited for transmission by S. cuniculi, and possibly because the dose of virus transmitted by fleas is considerably greater than that by mosquitoes or other agents.

Rabbits given an excess of air-dry food but only small amounts of drinking water had a lower food intake and lost more weight than those given food and water freely. They lost weight because they had less digesta in the gut and less water in the skin, and had catabolized more tissue. Their response to water shortage was similar to that seen in other grazing mammals. With low food intake, gut contents fell and the digestibility of food rose, while the daily mass of and water loss in faeces fell; the moisture content in faeces remaining the same. Dehydrated rabbits produced relatively small amounts of urine, up to 1.9 M urea, which was twice as concentrated as that of rabbits given water freely. The rabbits were not able to reduce their requirement for water to less than 55% of their total intake of food and water. As pasture species in mediterranean-type environments become relatively dry in summer and contain only 10 to 5% water, a shortage of water in natural pastures in those areas may, therefore, limit the amount of food which rabbits can use, and the ability of rabbits to survive in summer would, therefore, depend upon the availability of succulent, drought-resistant perennial vegetation.

Shortage of water in natural pastures led to a sharp decline in a large rabbit population in arid, northeastern
South Australia. The pastures were dry and some rabbits drank at springs and water troughs.
Further from water, rabbits climbed trees and shrubs to obtain succulent leaves and twigs. Rabbits
provided with water maintained their weight and apparently survived better than those which did not
drink. It seems unlikely that the rabbits lost weight because the water shortage reduced the amount of dry
food they could eat. In caged rabbits, water shortage limits food intake but also results in low gut fill;
whereas the wild rabbits had the normal amount of digesta in their guts. It is more likely that, as the
pastures became dry, rabbits ate woody twigs and bark which were moist enough to meet their water
requirements but contained too little digestible energy for maintenance. The water shortage apparently
arose because rabbits were numerous and had eaten out the succulent pasture plants. Normally, it takes a
long drought to reduce arid-zone plants to dry straw, and overgrazing is probably the usual cause of a
lack of adequate water for rabbits.

Rabbits could be controlled by various combinations of warren ripping, poisoning and fumigation, without the need for clearing roadside Eucalyptus spp.

The health and nutritional status of a population of the hairy-nosed wombat Lasiorhinus latifrons
inhabiting the Blanche Town region of South Australia was assessed over a period of 18 months, 12 of
which were during a drought. Measurements were made of body morphology, haematological and
biochemical constituents and vitamin and trace element status of animals in the field: these were
examined in relation to the chemical composition of stomach contents and of faeces. During the study
period, changes in body weight, body condition and selected haematological and chemical constituents
were closely associated with changes in the quantity and quality of food, as measured by faecal nitrogen
and organic matter and by a plant growth index. It appears that wombats in the Blanche Town region
survived a drought of 12 months duration with minimal loss of body tissues and maintained
physiological functions.

Background: Dengue is an emerging public health problem in Tarai Region of Nepal. The most affected are among the poorest populations living in remote, rural areas and urban slums who have even no access for medical treatment. This study was carried out with the objective of the determining the serodiagnosis of dengue in symptomatic individuals and comparing it to IgM ELISA. Methods: One hundred eighty three samples were collected from the suspected cases having clinical symptoms of dengue in the Tarai region of Nepal during September to October 2007. Particle Agglutination (PA) assays was performed and it was compared with IgM capture ELISA. Results: Out of the total of 183 serum samples that 55(30%) samples were positive by PA assay. When compared with IgM-capture ELISA, a 50 of 55 were positive (sensitivity of 98% and specificity of 96%; a positive prediction value of 90% and negative prediction value of 99%). Conclusions: The finding of this study showed that dengue is firmly established in low endemic Tarai region of Nepal. The sensitivity and specificity of PA assay is acceptably high and will be useful in rural areas of Nepal. Key words: Dengue, Tarai region, Particle agglutination test, IgM capture ELISA DOI: 10.3126/jnhrc.v7i1.2276 Journal of Nepal Health Research Council Vol. 7, No. 1, 2009 April 29-32