Study of the dog population and the rabies control activities in the Mirigama area of Sri Lanka.

The national health authorities of Sri Lanka have adopted a combined strategy of rabies vaccination and stray dog removal to control endemic dog rabies. Despite the control efforts, an increase of animal and human rabies cases has occurred since 1994. As a consequence, a project to evaluate the national rabies control program has been started and a study focussing on the dog population and rabies control activities in a limited area of Mirigama was conducted. Information on canine abundance and the accessibility of dogs for rabies vaccination was obtained by a household survey, vaccination of dogs against rabies at several vaccination points, collar-marking, and transect line recapture. The number of unvaccinated dogs was estimated by using Bayesian methodology. The estimated number of dogs per square kilometre was 87 (95% credibility interval: 80, 93) for owned dogs and 108 (100, 116) for owned and ownerless dogs. Coverage after the immunisation campaign was 57.6% (53.3, 61.9%) if vaccination at the vaccination points was considered and 66% (60.4, 72.0%) if recently provided vaccination by private veterinarians was also taken into account. The proportion of households with at least one dog vaccinated varied between 59.1 and 94.2% within the catchment area of the different vaccination points. Unvaccinated dogs were puppies (12%), ownerless dogs (57%), and owned dogs, which were not presented for vaccination (31%). In order to improve the rabies immunisation coverage among dogs and to achieve complete elimination of rabies it was recommended that the 95% catchment area of each vaccination point be assessed, the distribution of vaccination points in the vaccination area be redefined if necessary, a system for the vaccination of dogs missing the vaccination campaign for dog owner-specific reasons be established, and an inexpensive marking system be used for vaccinated dogs.

Pertussis surveillance in Switzerland, 1992 to 1997 - a large epidemic in 1994. What next?

Cases of whooping cough have been recorded by the Swiss Sentinel Surveillance Network Sentinella (SSSN) since June 1991 to monitor pertussis trends in Switzerland and to assess the current vaccination strategy. The Sentinella network consists of a sampl

The epidemiology of bite and scratch injuries by vertebrate animals in Switzerland.

Pet and wildlife populations are a potential source of various public health problems, and injuries and complications due to animal bites and scratches are the most obvious. As no population based data on the frequency of animal bites were available at a national level in Switzerland, a study was conducted by the Swiss Sentinel Surveillance Network. The objectives of this study were to estimate the incidence of medical consultations due to bite and scratch injuries in humans caused by vertebrate animals, to identify possible risk factors, and to assess bite management habits in primary health care. An annual bite and scratch incidence rate of 325 per 100,000 population was estimated. Consultations peaked during the summer months and geographical differences in the reported incidence were observed. Dogs accounted for more than 60% and cats for about 25% of all cases reported. Animal bites and scratches were frequent in persons under 20 years of age. In most ages, the incidence was higher among women than among men, but not in children under the age of ten years. The incidence of cat bites was especially high in adult women. Bites to the head and neck were most frequent in infants and young children and accounted for approximately one third of the reported cases in this age group. Patients sought medical care principally for primary wound care (52.0%) and for vaccination advice (29.6%). Rabies postexposure prophylaxis was initiated in 1.1% of patients. Wound infection was reported in 10.9% of cases, with cat bites/scratches being more often infected than injuries due to dogs. Hospitalization was reported in 0.3 % of patients. Data from the emergency department of two district hospitals showed that head and neck injuries were more frequent in out-patients and a higher proportion of persons presented with wound infections (14.1%). The hospitalization rate for emergency department visits was 4.7%. Animal bites and scratches are common events in Switzerland. They represent a public health issue of growing importance due to the steadily increasing pet population. A practice based sentinel surveillance system may be an appropriate tool to monitor national trends in animal bites and scratches.

Field evaluation of a dog owner, participation-based, bait delivery system for the oral immunization of dogs against rabies in Tunisia.

We evaluated a dog owner, participation-based, bait delivery system for the oral immunization of dogs against rabies. In a field study in a semirural area of northern Tunisia, dog owners were asked to come to temporary bait delivery sites. A total of 314 baits were given to 178 dog owners in four sites. The experimental baits used consisted of a freeze-dried core unit containing sulfadimethoxine (SDM) as a biological marker and an aromatized paraffin envelope. No vaccine was used. Preliminary tests had shown that by using a rapid commercial card test, positive SDM serum levels were detected in more than 95% of dogs up to two days after bait ingestion. During the two days following bait delivery, we visited more than 95% of all households in the study area and took blood samples from as many owned dogs as possible. Unconsumed baits were recovered and human contacts with the bait matrix were recorded. The campaign required 7.6 person-min per bait and 13.5 person-min per dog owner for providing baits, gloves, and instructions. The estimated average cost effectiveness ratio per dog accepting a bait was 1.7 US dollars. From the indications given by the dog owners and the results of the SDM test, it was concluded that 85-90% of the owned dogs in the study area had consumed a bait at least partially. Of 314 baits delivered, 78.7% were fully consumed by dogs and 4.1% were recovered during the household survey. The remaining baits (17.2%) that were not recovered were either not consumed or only partially consumed by the target dogs (3.7 baits per 100 inhabitants). These baits probably remained within the highly populated areas and were potentially accessible to other domestic animals and other nontarget species, including humans. Twenty-five unprotected human contacts with baits were recorded (1.7% of all inhabitants). Our study has demonstrated the potential of dog owner based bait delivery. This technique is simple and efficient, particularly if the human population is accustomed to mass immunization in defined centers. Before applying this method on a large scale with live vaccine loaded baits, further studies should focus on minimizing the number of human contacts with the vaccine bait, systematizing contact identification and establishing structures in ensuring proper treatment if exposure to vaccine should occur.

Field evaluation of two bait delivery systems for the oral immunization of dogs against rabies in Tunisia.

Two bait delivery systems for the oral immunization of dogs against rabies were tested in small scale field trials in a semi-rural area in Tunisia: bait delivery to owned dogs during door to door visits of households (door to door baiting) and distribution of baits on transect lines (transect line baiting). A prototype bait (DBL2) configured for industrial production and containing either sulfadimethoxine (SDM) as a systemic marker or Rhodamine B as a topical marker was used. The overall proportion of dogs which took a bait and presented topical marker staining after door to door baiting was 59.1%. The total time and costs spent per bait accepting dog averaged 34 person minutes and US$4, respectively. Unconsummated baits were readily recovered. No unprotected human contacts with baits were recorded. Door to door baiting is a very specific but time-consuming method that enables a safe administration of vaccine baits to owned dogs. For transect line baiting, baits were distributed at a density of ca 3000 baits per km2 along double transect lines. Baits were recovered after 20 h. According to the proportion of SDM positive serum samples, 24.1% of owned dogs in the baiting area had consumed baits. Of all owned and ownerless dogs, presumably free-roaming during transect line baiting, > 40% had consumed baits. The total time and costs spent per bait accepting dog averaged 48 person minutes and ca US$20, respectively. The household census revealed 32 direct human contacts with the bait matrix which corresponds to 1.4% of inhabitants. Placing baits on transect lines gives the possibility to vaccinate dogs not accessible by vaccination systems which base on dog owner participation. However, the method is not specific, less safe than other systems, not easily accepted by the human population, and costly.

Impact of polymerase chain reaction on clinical pertussis research: Finnish and Swiss experiences.

Since April 1993 in Finland and March 1994 in Switzerland, polymerase chain reaction (PCR) has been used routinely nationwide for the diagnosis of pertussis. Nasopharyngeal specimens from 3794 patients suspected of having pertussis and 1125 controls were tested. Finnish and Swiss assays found 23% and 36% of clinical specimens positive, respectively. PCR showed a higher incidence of pertussis infection among 1- to 6-year-old children in Switzerland than in Finland (P < .001). This difference may be due to the booster dose of vaccine given at 2 years of age in Finland but not in Switzerland. In Finland, PCR-confirmed asymptomatic cases were more common among children <7 years old than in older children (P < .001), whereas older children tended to have symptomatic infection. The use of PCR markedly improves the diagnosis of pertussis and opens new perspectives for epidemiologic and vaccine efficacy studies.

[Monitoring of a whooping cough epidemic 1994/95 in Switzerland using the sentinel notification system. Sentinella Registry]. / Erfassung einer Keuchhusten-epidemie 1994/95 in der Schweiz durch das Sentinella-Meldesystem. Sentinella-Arbeitsgemeinschaft.

Since June 1991 pertussis cases have been reported in the Swiss Sentinel Network (Sentinella). A total of 150-200 general practitioners, physicians specialized in internal medicine, and pediatricians participate in this system on a voluntary basis. Of the three specialties involved, this non-randomized sample represents 3.0%-3.5% of all physicians registered in Switzerland. The objective of this surveillance system is to monitor clinical pertussis over time. The case definition included all patients with a cough illness lasting at least 14 days with one of the following: paroxysms of cough, inspiratory "whoop", post-tussive vomiting (sporadic cases), or an epidemiological link to a pertussis case (epidemic cases). A laboratory diagnosis based on the polymerase chain reaction technique (PCR) was available for 82.7% of cases reported in 1994 and 1995. Of these, 27.7% had a positive PCR result. Reports of epidemic pertussis tested for Bordetella pertussis by PCR were confirmed by the laboratory in 46.5% of cases. The laboratory confirmation rate was more than twice as high among epidemic cases than among sporadic cases (20.7%). The crude incidence rate of whooping cough was 70 cases per 100,000 population per year in 1992 and 1993. Compared to previous years, pertussis incidence was significantly higher in 1994 and 1995 (370 cases per 100,000 population and 280 cases per 100,000 population respectively). The increase in reports was especially marked between July and October 1994 and whooping cough became epidemic in the third trimester of 1994 and at the beginning of 1995. In these 2 years, Switzerland experienced an estimated 40,000 clinical pertussis cases. Based on the proportion of PCR-positive pertussis cases in the sentinel sample, 12,500 of these would have been laboratory-confirmed. Most cases were observed in infants and in children up to 6 years of age. Assuming a vaccination coverage of 90%, the global efficacy of vaccination (3 or more doses versus less than 3) for 1994 and 1995 among children aged 12 to 47 months and not born before 1991 was 0.74 (0.59 and 0.88 for a vaccination coverage of 85% and 95% respectively). Vaccine efficacy was higher in PCR-positive cases (0.87; 0.79; 0.94) than in PCR-negative cases (0.54; 0.27; 0.78). Vaccination efficacy estimates on the basis of surveillance data are certainly less precise than those inferred from clinical trials. However, our results indicate that the efficacy of vaccination in children significantly declined with increasing age. Whooping cough still has the potential to cause epidemics in Switzerland in spite of a high vaccination coverage. With the introduction of acellular pertussis vaccines and new vaccination schemes in Switzerland, the Swiss Sentinel Network fulfills an important task as a monitoring system and contributes to the evaluation of new vaccination strategies.

Measles, mumps, and rubella: monitoring in Switzerland through a sentinel network, 1986-94. Sentinella Arbeitsgemeinschaft.

STUDY OBJECTIVES: Since 1986, the national sentinel network in Switzerland (Sentinella) has collected reports of measles, mumps, and rubella cases in order to evaluate the impact of the Swiss MMR vaccination campaign (started in 1987) on disease frequency. DESIGN: Passive surveillance of clinical measles, mumps, and rubella cases through a voluntary physician based sentinel network in Switzerland. SETTING: Each year between June 1986 and May 1994, 150 to 200 general practitioners, specialists in internal medicine, and paediatricians in private practice covering the whole country have reported weekly numbers of consultations. PATIENTS: Every patient who fulfilled the case definition and consulted a physician participating in the Sentinella network was reported. MAIN RESULTS: Since 1986, the annual number of reported measles cases per physician has fallen--from 1.3 (95% confidence interval (CI) 1.11, 1.50) in 1986-87 to 0.4 (95% CI 0.30, 0.50) in 1993-94. A decreasing trend, although less pronounced, was also observed for rubella. An initial decrease in mumps cases was reported--from 1.8 (95% CI 1.57, 2.03) annually reported cases per physician in 1986-87 to 0.7 (95% CI 0.55, 0.83) in 1989-90. This was followed, however, by a net and sustained increase. In 1993-94, the mean annual number of reported mumps cases per practitioner reached 4.7 (95% CI 4.34, 5.01) which was the highest level since surveillance had started. Over the whole eight year period, reported mumps cases, in terms of the percentage of consultations, were four times more frequent in the French speaking part of Switzerland than in the rest of the country. The proportion of mumps cases in people reported to have been vaccinated also increased--from 10% in 1986-87 to 60% in 1993-94. CONCLUSIONS: Reductions in cases of measles and rubella but an appreciable increase in mumps cases have been observed in the past three years in Switzerland. This findings, combined with increasing vaccination coverage and the fact that 60% of mumps cases are reported in vaccinated people, suggests that the overall efficacy of the mumps vaccines used in Switzerland is probably below 80%. Under these conditions the goal of eliminating mumps will probably not be reached. Further studies are needed to evaluate the efficacy of the different mumps vaccines used.

Test of three bait types for oral immunization of dogs against rabies in Tunisia.

Chicken heads and two types of artificial bait were tested in Tunisia during two field trials in a waste disposal site carried out in 1988 and 1989 to compare their effectiveness as vehicles for the oral administration of antirabies vaccine to free-roaming dogs. Baits were made available for 36 hr and those that disappeared or were consumed were replaced on several occasions. In 1988, an artificial bait composed of fat and fishmeal (artificial bait type I) was tested. In the second trial, chicken heads and an artificial bait composed of polymerized fishmeal and wax (artificial bait type II) were compared. The vaccine containers were loaded with a topical marker (rhodamine B or methylene blue) to identify animals that had consumed baits. The artificial type I bait tested in 1988 was poorly accepted, but in the second trial, the number of chicken-head baits probably taken by dogs was more than seven times greater than the number of artificial type II baits taken. Thirteen dogs observed during the day showed topical marker staining. In both trials, most baits were taken during the night when dog activity in the waste disposal site was at its maximum. Artificial baits were characterized either by their lack of thermostability (type I, melting) or a certain attractiveness for cats (type II, fish flavor). Chicken heads fulfill established requirements for baits for vaccine delivery. They are well-accepted by free-roaming dogs, inexpensive, usually easily available at local markets, unattractive to humans, relatively easy to store in large quantities, and easy to handle.

[The Sentinella reporting system in Switzerland exemplified by pertussis monitoring from 1991 to 1993. Sentinel Work Group]. / Das Meldesystem "Sentinella" in der Schweiz am Beispiel des Pertussismonitorings von 1991 bis 1993. Sentinella-Arbeitsgemeinschaft.

Since 1986, 150 to 180 general practitioners, internists and pediatricians in private practises have reported morbidity data to the Swiss Federal Office of Public Health within the Sentinella network. Data on a certain number of infectious diseases, some noninfectious diseases and other reasons for consultation are collected through this reporting system. The number of participating physicians corresponded to 2.3 to 3.1% of all family practitioners for each of the three specialties. They also covered approximately 2.7% of the total annual number of consultations in Switzerland. In 1992/93, all cantons and all half-cantons except Nidwalden and the two half-cantons of Appenzell were represented by at least one physician who reported during 75% or more of the total reporting period. When compared to other countries, the network density of the Swiss Sentinel network is high. Since 1986, several infectious diseases have been continuously monitored by the Sentinella system (measles, mumps, rubella, influenza). Surveillance of pertussis, which was started in 1991, will be continued for several years. According to these data, an annual pertussis incidence rate of 60 out of 100,000 population and 100 out of 100,000 population was estimated in 1991/92 and 1992/93, resp. More than 55% of cases were children aged between one and eight years. Of these children, 70.4% were reported to be vaccinated, and 62.6% had a well-documented vaccination status (based on a vaccination certificate). In 95.6% of these cases, at least three vaccine doses were given.(ABSTRACT TRUNCATED AT 250 WORDS)

[Mumps epidemiology in Switzerland: results from the Sentinella surveillance system 1986-1993. Sentinella Work Group]. / Mumps-Epidemiologie in der Schweiz: Ergebnisse der Sentinella-Uberwachung 1986-1993. Sentinella-Arbeitsgemeinschaft.

UNLABELLED: Since 1990, there have been reports of an increasing number of mumps cases in Switzerland, in particular among vaccinated children, and of local outbreaks of mumps. Using data from the Sentinella reporting system, a network of voluntary participating doctors (general practitioners, internists and paediatricians, yearly average: n = 141), trends and factors influencing mumps incidence in the general population were assessed during the last seven years. Following an initial decline in mumps reports, since 1990, there has been a continuous and marked increase in reports from a minimum of 0.7 cases per physician and year in 1989/90 to a near five-fold increase of 3.3 cases in the last reporting period from June-December 1993 (calculated for one year). Half of this increase, which is reflected in a doubling of the number of cases reported in 1986/87, is explained by an increase in cases among vaccinated children. The trend in mumps cases contrasts with that of measles and rubella, where there has been a clear decline in these reports since 1986 (approximately 70-80%). Complications were reported in 75 (4.0%) of the total number of mumps patients (n = 1894); in 2/5 of the cases this was a meningitis, in 1/3 an orchitis. Based on available data on vaccination coverage, the estimated efficacy of the mumps vaccines against parotitis is between 47-77%; this is clearly lower than the corresponding figure for measles (91-97%) and rubella (89-97%) vaccines. The relatively low efficacy against parotitis is mainly due to a protective level of 13-73% of the vaccines containing the Rubini strain. The estimated efficacy of the Rubini vaccines against complications is 50-81%; it is nearly 60-90% if a possible reporting bias is taken into consideration. CONCLUSIONS: 1. The Rubini strain vaccines, which are the most commonly used in Switzerland, seem to have played an important role in the clear increase in mumps cases since 1990. 2. The situation seems more favourable concerning the efficacy against complications of the vaccines used. 3. Our data support the high efficacy of all measles and rubella vaccines. 4. The surveillance of MMR by the Sentinella reporting system provides a useful and effective manner to evaluate the MMR vaccination programme.

The ecology of dogs and canine rabies: a selective review.

Although dogs are the most widespread and abundant of all carnivores, the role of the dog in human cultures and its impact on the environment have rarely been studied. These subjects are reviewed in the context of canine rabies. To understand the epizootiology of canine rabies, the ecology and population biology of the dog must be considered. Information on dog populations (in relation to different habitats, cultures, social strata of human populations and epizootiological situations) was collected in Nepal, Sri Lanka, Switzerland and Tunisia. In Switzerland (and Western Europe in general), rabies is maintained and spread by red foxes. The low prevalence of rabies in dogs may be explained by restrictive practices of dog-keeping and high rates of vaccination. In the other areas examined, dogs are poorly supervised and their population densities are high enough to support rabies, although it is questionable whether canine rabies exists independently of a wildlife reservoir. Dog-keeping practices, high rates of exposure and various cultural factors may lead to a high human rabies mortality rate. Nevertheless, dogs in these areas remain sufficiently accessible for vaccination and well-executed control programmes could prove successful.