The spatio-temporal dynamics of a post-vaccination resurgence of rabies in foxes and emergency vaccination planning.

We used a simulation model to study the spatio-temporal dynamics of a potential rabies outbreak in an immunized fox population after the termination of a long-term, large-scale vaccination program with two campaigns per year one in spring and one in autumn. The 'worst-case' scenario of rabies resurgence occurs if rabies has persisted at a low prevalence despite control and has remained undetected by a customary surveillance program or if infected individuals invade to the control area. Even if the termination of a vaccination program entails such a risk of a subsequent new outbreak, prolonged vaccination of a wild host population is expensive and the declining cost-benefit ratio over time eventually makes it uneconomic. Based on the knowledge of the spatio-temporal dynamics of a potential new outbreak gained from our modelling study, we suggest "terminating but observing" to be an appropriate strategy. Simulating the decline of population immunity without revaccination, we found that a new outbreak of rabies should be detected by customary surveillance programs within two years after the termination of the control. The time until detection does not depend on whether vaccination was terminated within the fourth, fifth or sixth years of repeated biannual campaigns. But it is faster if the program was completed with an autumn campaign (because next-year dispersal then occurs after a noticeable decrease in population immunity). Finally, if a rabid fox is detected after terminating vaccination, we determine a rule for defining a circular hazard area based on the simulated spatial spread of rabies. The radius of this area should be increased with the time since the last vaccination campaign. The trade-off between the number of foxes potentially missed by the emergency treatment and the cost for the emergency measures in an enlarged hazard area was found.

Chance and risk of controlling rabies in large-scale and long-term immunized fox populations.

The large-scale immunization of European fox populations against rabies is currently under the microscope for reducing the considerable expenditure without putting public health at risk. Empirical knowledge is inadequate to interpret the lasting sporadic incidences and, therefore, to verify the final success of the immunization campaigns. By using a proven simulation model we show that rabies can persist on a very low level in the form of spatio-temporal moving infection clusters within a highly immunized fox population. We found further: (i) the existence of a threshold after which the chance of eradicating the disease by vaccination increases clearly, and (ii) that at least six years of 70% mean immunization rate are required to guarantee a likely success.

[New answers to the questions of continued rabies control in Germany]. / Neue Antworten auf die Frage der weiteren Tollwutbekämpfung in Deutschland.

With the assistance of a computer simulation model changed rabies spreading in immunised fox populations is examined. The influence of long-time and large-scale vaccination on the virus-host-system is analysed and new effects and their causes are shown. Rabies can persist for many years despite continuous vaccination with high immunisation rates. Because of the characteristic low-level prevalence the disease is provable by random only without using untreatable surveillance measures. Therefore one has to keep in mind the possibility of continued rabies within areas suspected rabies-free by surveillance. Consequences for emergency programs after termination of the vaccination will be discussed.

[The complication incidence after surgical treatments of mouth, jaw and facial tumors in patients over 70]. / Zur Komplikationsdichte nach operativen Behandlungen von Mund-Kiefer-Gesichtstumoren bei Patienten jenseits des 70. Lebensjahres.

After operative therapy of tumors of mouth, jaws and face by patients older 70 years the frequency of complications were 26%. Local and systemic disturbances had nearly similar frequencies. Preexistent diseases, therapeutic concepts and methods of anaesthesia influenced as well frequencies of complications as postoperative lethality. In the analysed group of elderly patients the lethality was unexpected low (2,4%).

[Implications of the reclassification study of tumors of the salivary glands of the head]. / Konsequenzen aus Studien zur Reklassifizierung von Geschwülsten der Kopfspeicheldrüsen.

A reclassification of 272 tumors of the salivary glands of the head resulted in a high proportion of new allocations, particularly among adenocarcinomas, adenoid cystic carcinomas, and pleomorphic adenomas, sometimes even involving a different assessment of the tumors' benign or malignant character. The implications for clinical practice and for prognostic studies are discussed.

[Monocentric retrospective study on the prognosis of adenoid cystic carcinoma]. / Monozentrische retrospektive Studie zur Prognose des adenoidzystischen Karzinoms.

Studies on 26 patients confirm the relevance of the factors tumour size and histological subtype for the prognosis of adenoid cystic carcinoma. For high risk tumours (tumour size over 3 cm, solid or tubular subtype) a postoperative adjuvant radiologic therapy is recommendable. The rate of wrong diagnoses found by reclassification is surprisingly high.

[Studies on the quality of leukoplakias of the oral mucosa and lips]. / Studien zur Dignität der Leukoplakien von Mundschleimhaut und Lippen.

Clinical and histological studies of 671 leukoplakias and 591 carcinomas of the oral mucosa and lips confirm that only inhomogenous leukoplakias may be qualified as precancerous lesions. Compulsory registration of inhomogenous leukoplakias as preneoplastic conditions is recommended.

[Retrospective multicenter study on carcinomas of the lips and oral cavity. The role of multiple malignancies]. / Multizentrische retrospektive Studie zum Lippen- und Mundhöhlenkarzinom. Untersuchung zur Rolle von Mehrfachmalignomen.

In a retrospective multicenter study the role of multiple cancer has been assessed in 2481 patients with carcinomas of the lips and oral cavity. In 3.2% of the cases the malignancies developed outside the maxillofacial area. In the majority of cases two malignant neoplasms were found. Most of them were histologically carcinomas. The bronchi and stomach were common localizations in patients with lip carcinomas, whereas patients with oral carcinomas exhibited mainly cancers of the breast, stomach and uterus. Sex-limited multiple cancers associated with oral carcinoma occurred predominantly in women. Surgery is the most common form of treatment. The prognosis for patients with lip carcinomas is significantly poorer when multiple cancers are present.

[Multicentric retrospective study on the carcinoma of lips and oral mucosa. Analysis of coherence between pre- and posttherapeutical categories of classification]. / Multizentrische retrospektive Studie zum Lippen- und Mundschleimhautkarzinom. Zusammenhangsanalyse zwischen prä- und posttherapeutischen Klassifizierungskategorien.

The coherence between prae- and posttherapeutical TNM findings had been checked up in a multicentrically registered patient material of 2,481 non-praetreated plate epithelium carcinomas of the lips and oral mucosa. Whereas the extension of the tumour has in the main been the same, the findings on lymph nodes had a trend showing essential deviations. In a two-dimensional examination of 851 histologically prepared preparations of lymph nodes, a prognostic relevance acc. to metastases had been registered for the characteristics palpation finding of the lymph node, tumour extension, tumour infiltration. Multidimensional analyses have to be realized.