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PubMedDate not supplied

Rat bites support need for in-home control: an epidemiologic study of rat bites in New York City, 1974-1978.

Rat bite reports in New York City during the years 1974-1978 were analyzed by time, place and person characteristics. Rat bites showed a general decline over the five-year period, from 226 reported bites in 1974 to 162 reports in 1978 (2/100,000 population). The decrease in reported bites from areas with active rodent control programs was twice the decrease from areas without such programs. The highest rates were reported from the health districts of the Lower East Side of Manhattan and the Williamsburg-Greenpoint section of Brooklyn. Rat bite rates in reported incidents are highest in children under age five, with no significant difference between sexes. Of the 1069 reported rat bites for the five-year period, 41.4% occurred on the hand, particularly the fingers, and 87.9% occurred indoors. The use of rat bite reports is a mechanism to identify high risk groups and areas of rodent infestation as well as indicating the success of rodent control programs.

Age Factors↗
PubMed1980

Nutritional adequacy and quality control of rodent diets.

One of the most often neglected variables in experimental investigations using rodents is the diet. Recent observations that diets can influence the response of a rodent to the drug, chemical or other factors under study, with biased interpretation of results, have drawn great interest. In order to be assured that the biologic response observed is a reflection of the material or condition under study, it is imperative that the diet provide essential nutrients in the proper proportions and that contaminants be kept to a minimum. Quality control is the key to these requirements; rodent diets can provide adequate nutrition, free of significant contamination. The diets which can be provided vary according to the degree of refinements; the three major types are (1) natural product, (2) semipurified and (3) chemically defined diets. Natural product diets may be open or closed formula, depending on the amount of information that the label reveals. Guaranteed analyses of proximate nutrients are provided but are of little use in assessing the nutrient value of the formulation. The National Academy of Sciences, National Research Council publications on laboratory animal nutrient requirements should be available to all investigators using experimental animals to help them evaluate the nutritional adequacy of the diets they use. Rats and mice may be considered together under some circumstances relative to crude dietary needs, but the Syrian golden hamster should be treated separately for purposes of diet. This species appears to digest foods more like a ruminant. An ideal diet for rodents is not on the horizon because of variable needs relative to different types of research and holding. Storage and shelf life of rodent diets also play important roles in providing adequate nutrition. Variations in moisture, temperature and exposure to other chemicals can affect the quality of the feed and research results. In addition, a number of chemical and biological contaminants have been found in rodent diets, and surveillance over such variables must be a part of all laboratory animal diet quality control. Federal regulatory mandates now require that investigators assure that nutrient requirements of animals are met and that diets are reasonably free from contamination. Accepted practices in good management, formulation, shipping and storage will help achieve these commendable goals.

Animal Feed↗
PubMed1972

Biological and behavioural studies of rodents as a basis for control.

Domestic rodents, particularly those living in urban populations, represent a serious public health problem, and effective control measures are required to deal with this threat to human health. Because of the characteristic interactions between individual animals, certain behaviour patterns occur in rodent populations that are of particular concern to control biologists. The genus Rattus is an extremely diverse group whose ecological requirements are variable and flexible, while the genus Mus, on account of its small size, limited range, and modest requirements in terms of food and water, is also very difficult to control. For any control operation a knowledge of the growth dynamics of domestic rodent populations is needed; after a period of logarithmic growth, population increases cease when the habitat is fully exploited. Consequently, control operations that merely remove some animals lead only to renewed population growth. Trapping, poisoning, and predation are traditional control measures of this kind. Environmental modification is a more certain, but more difficult, approach. The use of chemosterilants offers some hope of radical control in the future, but at present, although some field trials have been made, these substances are not available for general use, one reason being their lack of specificity. Another problem connected with the use of chemosterilants is that, on account of the sexual behaviour and physiology of domestic rodents, it would be necessary to reach nearly 100% of the population to obtain effective control.

Animals↗
PubMed1987

Transplantation of insulin-like growth factor-II-secreting tumors into nude rodents.

Restricted supplies of insulin-like growth factor II (IGF-II) have severely limited investigation of the in vivo actions of this hormone. To circumvent this problem, we have developed an in vivo rodent model in which rat (r) IGF-II-secreting cells (18, 54-SF) are transplanted into congenitally immunodeficient (nude) rats and mice. These cells proliferate and form discrete tumors that contain rIGF-II and abundant IGF-II receptors. The tumors also secrete rIGF-II into the circulation, resulting in plasma rIGF-II concentrations many-fold greater than those in control rodents (81 +/- 19 vs. less than 10 ng/ml, rats; 159 +/- 28 vs. 18 +/- 5 ng/ml, mice; P less than 0.05, both groups). There was no significant difference between the tumor-bearing and control rodents in either body weight or tail length. The tumor-bearing rodents did have significantly lower concentrations of IGF-I (296 +/- 23 vs. 527 +/- 67 ng/ml, rats; 300 +/- 26 vs. 482 +/- 70 ng/ml, mice; P less than 0.05, both groups), suggesting that the increased concentrations of rIGF-II may have inhibited IGF-I production or secretion. This animal model may be used to explore the biological effects of increased plasma IGF-II concentrations.

Adenoma↗
PubMed1999

The Norway rat as a reservoir host of Cryptosporidium parvum.

The potential of Norway rats (Rattus norvegicus) to spread the parasite Cryptosporidium parvum was investigated by examining parasite prevalence in relation to the structure and movements of three permanent rat populations living on farmland in Warwickshire (UK) from October 1994 to March 1997. One population lived among a group of farm buildings housing cattle, while the other two had no contact with livestock, one living around a pond and its outflowing stream and the other on a rubbish tip. Overall, parasite occurrence was 24% (n = 438), but it varied according to body weight (age) with 40% of juveniles (< or =100 g) infected decreasing to 12% for adults >400 g, suggesting that actively breeding populations are potentially more likely to spread the parasite than non-breeding populations. There was no difference in prevalence between the three populations. The parasite was detected in more males (29%) than females (19%). Seasonally, on the livestock farm, prevalence was significantly lower in autumn (10%), but varied little (31-36%) from winter to summer. In contrast, on the arable farm, prevalence peaked in summer (50%) with a trough in winter (6%). Infection in rats appeared to last <67 days. Rats living on the livestock farm had home ranges largely confined to the cattle sheds, thereby maintaining a potential source of infection for livestock if rodent control was not part of a decontamination program. Equally, rats living around the pond on the arable farm provided a source of oocysts to contaminate the pond water, as well as being able to carry the parasite to nearby farm buildings or even to neighboring farms.

Age Factors↗
PubMed2004

Endogenous ghrelin in pancreatic islets restricts insulin release by attenuating Ca2+ signaling in beta-cells: implication in the glycemic control in rodents.

Ghrelin, isolated from the human and rat stomach, is the endogenous ligand for the growth hormone (GH) secretagogue receptor, which is expressed in a variety of tissues, including the pancreatic islets. It has been shown that low plasma ghrelin levels correlates with elevated fasting insulin levels and type 2 diabetes. Here we show a physiological role of endogenous ghrelin in the regulation of insulin release and blood glucose in rodents. Acylated ghrelin, the active form of the peptide, was detected in the pancreatic islets. Counteraction of endogenous ghrelin by intraperitoneal injection of specific GH secretagogue receptor antagonists markedly lowered fasting glucose concentrations, attenuated plasma glucose elevation, and enhanced insulin responses during the glucose tolerance test (GTT). Conversely, intraperitoneal exogenous ghrelin GH-independently elevated fasting glucose concentrations, enhanced plasma glucose elevation, and attenuated insulin responses during GTT. Neither GH secretagogue receptor antagonist nor ghrelin affected the profiles of the insulin tolerance test. In isolated islets, GH secretagogue receptor blockade and antiserum against acylated ghrelin markedly enhanced glucose-induced increases in insulin release and intracellular Ca2+ concentration ([Ca2+]i), whereas ghrelin at a relatively high concentration (10 nmol/l) suppressed insulin release. In single beta-cells, ghrelin attenuated glucose-induced first-phase and oscillatory [Ca2+]i increases via the GH secretagogue receptor and in a pertussis toxin-sensitive manner. Ghrelin also increased tetraethylammonium-sensitive delayed outward K+ currents in single beta-cells. These findings reveal that endogenous ghrelin in islets acts on beta-cells to restrict glucose-induced insulin release at least partly via attenuation of Ca2+ signaling, and that this insulinostatic action may be implicated in the upward control of blood glucose. This function of ghrelin, together with inducing GH release and feeding, suggests that ghrelin underlies the integrative regulation of energy homeostasis.

Animals↗
PubMed1991

An experience in the control of plague in Botswana.

In October 1989, cases of human plague started to occur in Boteti district of Botswana. One hundred and seventy cases were recorded in total from 15 October 1989 to 6 April 1990. There were 12 deaths, giving a case fatality rate of 7%. All cases were of the bubonic type. A concerted control strategy based on sentinel surveillance, involving public education, flea and rodent control, chemotherapy and chemoprophylaxis controlled the epidemic.

Adolescent↗
PubMedDate not supplied

[Guidelines for the organization and management of disinfection and disinfestation from rodents and mosquitoes].

Two recent legislative acts (D.P.C.M. 29.11.2001 and D.G.R. Veneto n. 2093, issued 02.08.2002) give to Local Health Authorities responsibility over surveillance of disinfestations activities. Authority over the implementation of these actions remains with the municipalities. Another legislative act (D.G.R. Veneto 3015) established the creation of a task force in order to define guidelines regarding new managerial methods toward disinfections, disinfestations and rodent control for public administration. The "Guidelines for the organization and management of disinfection and of rodent and mosquito control" redefine the roles for the public administration units involved, propose a new organizational model and an innovative managerial approach to activities, provides technical recommendations for the preparation of specific contracts and for the implementation of disinfestation actions. Finally, the guidelines include a proposal for the development of regulations supporting the technical propositions.

Animals↗
PubMed1993

Use of an oestrogen, androgen or gestagen as a potential chemosterilant for control of rat and mouse populations.

Three synthetic steroids were evaluated as potential chemosterilants for rodent control. Ethinyl oestradiol, methyl testosterone or Org 5933, a synthetic gestagen, were incorporated into paraffin blocks containing cereal grains and offered to laboratory rats and mice in addition to their standard laboratory diet. Ethinyl oestradiol (50 mg kg-1 paraffin block) was highly unpalatable to female rats, and the amount of steroid ingested was not sufficient to interfere with their oestrous cycles or inhibit ovulation. Methyl testosterone (5000 mg kg-1 paraffin block), although not as palatable as untreated blocks, was effective in inducing almost immediate infertility in female rats and mice at an ingested dose of about 35 micrograms g-1 body weight day-1. This infertility persisted throughout the duration of treatment, and lasted for several weeks after the cessation of treatment. Male rats became infertile after 3 months of treatment owing to suppression of spermatogenesis. Female rats developed a specific aversion to methyl testosterone when they were pregnant or lactating; it was therefore not possible to masculinize the brains of their female offspring. In mice, the androgen treatment induced high levels of aggression in the females so that they fought with males and with one another. One female died of her wounds. Org 5933 (4 mg kg-1 paraffin block) was highly palatable to female rats and mice, and at doses of about 420 ng g-1 body weight day-1 was effective in inhibiting ovulation in rats within 3 to 4 days after the start of treatment. This infertility persisted throughout the duration of treatment, and the animals conceived within 5 days of cessation of treatment. A dose of about 930 ng g-1 body weight day-1 was not completely effective in inhibiting ovulation in mice, but females that became pregnant during treatment gave birth to dead young. When the gestagen was given to female rats and mice in the last few days of pregnancy, the duration of gestation was significantly prolonged, and most young were born dead; some of the females also died in labour. The gestagen did not appear to inhibit lactogenesis, since the few animals that gave birth to live young reared them normally for the first 5 days of life. These results show that either methyl testosterone or Org 5933 in paraffin blocks could perhaps be used as a chemosterilant for the control of rat and mouse populations.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗