Rabies, an emerging disease in Korea

Since the first rabies case was reported in a dog in 1907, the disease was enzootic up to 1975 in Korea. After a steady decrease in the number of rabies cases from 1976 to 1984, no case was reported for 8 years from 1985 to 1992. Then, a resurgence of the disease was noted in 1993, and a continuous increase of rabies cases was observed during the following years. This report provides information on rabies in South Korea during the reemerging period 1993-2003. A total of 364 rabies cases in five different animal species and five deaths in human beings as a result of rabies were reported. Cattle and dogs accounted for 46.4% and 40.4% of total animal cases, respectively, and raccoon dogs commanded an overwhelming majority (44/48) of rabies cases in wildlife animal species. All animal and human rabies cases occurred only in two provinces, Gyeonggi and Gangwon; majority of them in two counties of Gyeonggi and one county of Gangwon province that border the demilitarized zone. From the three counties, the disease continued to expand to the other areas of the two provinces. The average monthly frequency of animal rabies cases during the 11-year period peaked in January, and the incidence was highest during winter. There were three major rabies outbreaks in animals and the number of animal rabies cases increased with time. Data indicate that the temporal patterns were attributable to the ethology of raccoon dogs in the areas of outbreak.     

Raccoon dog rabies surveillance and post-vaccination monitoring in Lithuania 2006 to 2010

Background

Oral rabies vaccination (ORV) in rabies infected regions should target the primary rabies vector species, which in Lithuania includes raccoon dogs as well as red foxes. Specific investigations on ORV in raccoon dogs are needed e.g. evaluation of vaccine effectiveness under field conditions. The objective of the current study was to investigate the efficacy of the ORV programme 2006-2010 in Lithuania by examining the number of rabies cases and estimating the prevalences of a tetracycline biomarker (TTC) and rabies virus antibodies in raccoon dogs.

Methods

From 2006 to 2010, 12.5 million rabies vaccine-baits were distributed by aircraft. Baiting occurred twice per year (spring and autumn), targeting raccoon dogs and red foxes in a 63,000 km² area of Lithuania. The mandibles of raccoon dogs found dead or killed in the vaccination area were analyzed by fluorescence microscopy for the presence of the TTC. Rabies virus sera neutralizing anti-glycoprotein antibody titres were determined using an indirect ELISA method and seroconversion (> 0.5 EU/ml) rates were estimated.

Results

During the study period, 51.5% of raccoon dog mandibles were positive for TTC. 1688 of 3260 tested adults and 69 of 175 tested cubs were TTC positive. Forty-seven percent of raccoon dog serum samples were positive for rabies virus antibodies. 302 of 621 investigated adults and 33 of 95 investigated cubs were seropositive. In the same time 302 of 684 and 43 of 124 tested samples were TTC and ELISA positive in spring; whereas 1455 of 2751 and 292 of 592 tested samples were TTC and ELISA positive in autumn. There was a positive correlation between the number of TTC and antibody positive animals for both adult and cub groups.

Conclusions

ORV was effective in reducing the prevalence of rabies in the raccoon dog population in Lithuania. The prevalence of rabies cases in raccoon dogs in Lithuania decreased from 60.7% in 2006-2007 to 6.5% in 2009-2010.     

Epidemiological characteristics of rabies in South Korea from 1993 to 2001

In the nine years from 1993 to 2001, 210 cases of rabies were recorded in domestic animals in South Korea; 115 cattle, 94 dogs and one farmed deer were affected. The annual incidence of rabies cases increased to a peak of 64 in 1998, and then decreased to about 30 cases per year. The cases were confined to the northern part of Kyounggi and Kangwon provinces. One hundred and forty-six cases (69.5 per cent) occurred in Kyounggi and 64 cases (30.5 per cent) in Kangwon province, and about 82 per cent of them were confined to two counties in Kyounggi province (29 per cent in Paju and 28.1 per cent in Younchun) and to Chulwon county in Kangwon province (25.2 per cent). However, over several years the outbreaks gradually moved south and east in both Kyounggi and Kangwon provinces. There were more rabies cases in cattle than in dogs, suggesting that the disease is transmitted by the sylvatic cycle. To investigate the relationship between rabies in domestic animals and wild animals, 107 wild animals, including Korean raccoon dogs, badgers, weasels and feral cats, were tested for rabies; 21 of the 67 Korean raccoon dogs tested (31 per cent) were infected. The cases in domestic animals were most common in winter, from December to February, and least common in summer, from June to September.     

An epidemic of sylvatic rabies in Finland--descriptive epidemiology and results of oral vaccination.

When rabies reappeared in Finland in April 1988, the country had been rabies free since 1959. Soon a picture of sylvatic rabies become evident, its main vector and victim being the raccoon dog (Nyctereutes procyonoides). Between 8 April 1988 and 16 February 1989, 66 virologically verified cases were recorded (48 raccoon dogs, 12 red foxes, 2 badgers, 2 cats, 1 dog and 1 dairy bull) in an area estimated at 1700 km2 in south-eastern Finland. The greatest distance between recorded cases was 67 km. A positive reaction with monoclonal antibody p-41 indicated that the virus was an arctic-type strain. A field trial on oral immunization of small predators was initiated in September 1988 using Tübingen fox baits according to the Bavarian model of bait distribution. Each bait contained 5*10(7) TCID50/ml modified live rabies virus (SAD-B19). The 6 months' surveillance indicate a seroconversion rate of 72% (N = 126) in the raccoon dog population, 67% (N = 56) in the red foxes and 13% (N = 16) in the badgers, when titers greater than or equal to 1.0 IU/ml are considered seropositive. In the whole follow-up period, no statistically significant difference could be detected between the raccoon dogs and red foxes in the rate of seroconversion or in the uptake of tetracycline from the baits. Notably high antibody levels were recorded in both raccoon dogs and red foxes within 4-5 months after vaccination. Of the seropositive animals, the proportion of animals with titers 3.0 IU/ml or greater was higher in raccoon dogs (73%) than in red foxes (51%) (x2 = 5.29, p less than 0.05). The trial shows that raccoon dogs can be immunized against rabies in the field with vaccine baits originally developed for controlling sylvatic rabies in foxes.     

Efficient distribution of oral vaccines examined by infrared triggered camera for advancing the control of raccoon dog rabies in South Korea

The field distribution of the oral rabies vaccine is effective in controlling the spread of rabies. The present study aimed to investigate efficient distribution locations based on the environment, contact rate, and consumption by target wildlife species in South Korea. The target species (Korean raccoon dogs, domestic dogs, and feral cats) accounted for 945 contacts (52.2%), in total 1,808 contacts. There were 863 (47.8%) contacts by non-target species. Raccoon dogs, a main reservoir of rabies in South Korea, had the highest contact rate (34.1%) among all species. The contact rate by target species was highest at riparian sites and bushy mountainous vegetation, where raccoon dogs are abundant. There was remarkable contact by raccoon dogs in mountainous areas below 150 m with bushy vegetation. Our results indicate that these locations are efficient areas for vaccine distribution, especially targeting the raccoon dog. Vaccines were continuously contacted with intervals ranging from one hour to one day. Vaccines at 94.4% of the distribution points were completely consumed within two weeks. The mean consumption rate was 95.2 ± 1.93% during the overall study period. These findings suggest that the oral rabies vaccine attracts wildlife including domestic dogs and feral cats. Our results suggest that low sections of mountainous areas with bushy vegetation and/or neighboring riparian areas are rich in target wildlife species (especially raccoon dogs) and are efficient locations for vaccine distribution to control rabies in South Korea.     

Radiographic evaluation of congenital vertebral anomalies in Korean raccoon dogs (Nyctereutes procyonoides koreensis)

BackgroundThe normal vertebral anatomy of Korean raccoon dogs and their variants require research attention as a prerequisite for identifying pathologies and anomalies.ObjectivesThis retrospective study aimed at describing the vertebral formula and congenital vertebral anomalies in Korean raccoon dogs (Nyctereutes procyonoides koreensis).MethodsRadiographs of 82 raccoon dogs (42 males, 40 females) acquired from May 2013 to June 2020 in the Gangwon Wildlife Medical Rescue Center were reviewed to evaluate the cervical, thoracic, and lumbar vertebrae of the spine.ResultsNormal morphology of all vertebrae was observed in 50 of the 82 raccoon dogs, and the vertebral formula was cervical 7, thoracic 13, and lumbar 7. Congenital vertebral anomalies were found in 32 raccoon dogs: transitional vertebrae (TV) in 31 and block vertebrae in 2. Two raccoon dogs had 2 types of vertebral anomalies: one had TV and block vertebra, and the other had 2 types of TV. Twenty-nine raccoon dogs had thoracolumbar TV (TTV) and 3 had lumbosacral TV. TTV was morphologically classified into 4 different types: unilateral extra-rib in 5 raccoon dogs, bilateral extra-ribs in 14, bilateral elongated transverse processes in 4, and an asymmetric mixed formation of extra-rib with elongated transverse process in 6.ConclusionsThis study showed that TTV is common in Korean raccoon dogs, and that the vertebral formula is relatively diverse. The bilateral extra-ribs type TTV is the most common variant, which is almost similar to normal rib to be confused the radiographic evaluation.     

Comparative immunogenicity and efficacy studies with oral rabies virus vaccine SAD P5/88 in raccoon dogs and red foxes.

A comparative study of immunogenicity and efficacy of the oral rabies virus vaccine SAD P5/88 in raccoon dogs and foxes was conducted. The raccoon dogs received 10(6.9) (n = 6), 10(6.3) (n = 6) or 10(5.7) FFU SAD P5/88 (n = 5) by direct oral application, and subsequently all animals seroconverted. The foxes received 10(7.2) (n = 4), 10(6.2) (n = 4), 10(5.2) (n = 4) and 10(4.2) FFU SAD P5/88 (n = 5) by the same route. On days 106 and 196 post vaccination 10 raccoon dogs and 16 foxes were challenged with a relevant street virus, respectively. All 10 raccoon dogs vaccinated with 10(6.3) (n = 5) or 10(5.7) FFU SAD P5/88 (n = 5) survived the challenge, whereas all control animals (n = 5) died of rabies. Two foxes vaccinated with 10(4.2) FFU and one fox vaccinated with 10(5.2) FFU died of rabies on day 7, 17 and 12 post infection, respectively. Also all control foxes succumbed to rabies. Our findings demonstrate that SAD P5/88 is not only an effective vaccine for oral vaccination of foxes but also for that of raccoon dogs.     

Epidemiological situation of rabies in Lithuania from 1990 to 2000

The epidemiological situation of rabies was investigated in Lithuania. Over the last decade, 2277 cases of rabies were registered among wild and domestic animals (mean number of cases per districts was 44). The highest distribution of rabies was found in the districts of Lazdijai and Utena (116 and 81 cases, respectively), and the lowest in the Svencioniai and Zarasai districts (one and eight cases, respectively). It was found that rabies among wildlife comprised 54% with the majority of cases being registered in foxes (626 cases, 27%) followed by raccoon dogs (470 cases, 21%). Within the last 3 years, cases of rabies among foxes and raccoon dogs increased significantly (three and six times, respectively), compared with the period from 1990 to 1997. Among domestic animals, 46% cases of rabies were registered, with cattle comprising 27%, and the cases among cats and dogs at 9 and 8%, respectively. During the period from 1993 to 1997 in Lithuania, 11,385 of humans were attacked by domestic and wild animals, and 21,173 humans were vaccinated against rabies for prophylactic reasons. Our survey has shown that, during the period from 1997 to 2000, the number of people attacked has increased drastically-31,348 (60%), but only 8021 (18%) of them were vaccinated.     

Maternal immunity against rabies in raccoon dogs.

The objective of the study was to examine possible maternally transferred antibodies (maAb) against rabies in raccoon dogs. Ten cubs born from a rabies-immune animal were bled on days 31, 36, 43, 50, 57 and 64 post partum. The geometric mean titres of the cubs were 1.19, 1.18, 0.45, 0.25, 0.25 and 0.16 IU/ml, respectively. Up to 36 days post partum maAb were detected in all cubs at levels > or = 0.5 IU/ml and at day 56 post partum all animals had maAb levels < 0.5 IU/ml. Based on the results of this study, it is suggested that vaccine baits should not be distributed before July if the vaccination campaign is aimed at immunizing young raccoon dogs as well.     

成都市区犬猫狂犬病病毒和弓形虫感染的调查

为了解四川省成都市区家养犬、猫狂犬病病毒及弓形虫的感染情况,采用商品化狂犬病病毒和弓形虫抗原快速检测试纸卡,对2010年8～10月间来自成都市区的103份家养犬以及75份家猫的唾液和血液样品进行检测;同时采用文献报道的PCR方法对家养犬血液样品中的弓形虫核酸进行检测。结果显示,103份家养犬唾液样品狂犬病病毒抗原均为阴性,而75份家猫唾液样品中,检出阳性样品5份(阳性率6.7%),可疑样品7份;103份家养犬血液样品弓形虫抗原阳性样品33份(32.0%),可疑样品22份,75份家猫血液样品中,检出阳性样品2份(阳性率2.7%),可疑样品3份。弓形虫核酸PCR检测结果显示,96份家养犬血液样品弓形虫核酸阳性样品57份(阳性率59.4%),与弓形虫抗原阳性和可疑样品总和所占比例基本一致(53.4%)。提示应重视源于家猫的狂犬病病毒和家养犬弓形虫对人的威胁。     

Risk-based cost modelling of oral rabies vaccine interventions for raccoon rabies

Distribution of oral rabies vaccine (ORV) is an effective but costly strategy to control raccoon rabies. Because of high costs, ORV for raccoon rabies in the U.S. has been limited primarily to epizootic areas, leaving extensive raccoon rabies regions without any ORV intervention. Several cost scenarios for ORV application in raccoon rabies enzootic and epizootic regions were modelled in New York State to obtain estimated costs of ORV baits per scenario and potential savings compared with a uniform ORV baiting strategy. These cost scenarios modelled at the census tract, level the application of ORV baits at different densities according to levels of risk defined by the observed number of raccoon rabies cases per km2 and the expected number of cases per km2 estimated with a Poisson regression model. Bait purchase costs were lower using the modelled cost scenarios than a uniform baiting strategy, for both the NYS enzootic region and the Long Island epizootic zone. The proportion of savings for the NYS enzootic region was 29.57%, and the proportion of savings for the Long Island epizootic zone was 38.9%. Use of these cost scenarios to determine bait distribution by rabies risk level should be considered to maximize efficacy and reduce costs of ORV interventions.     

鼬獾群体中狂犬病中和抗体调查与分析

采用荧光抗体病毒中和试验（FAVN）即固定病毒一稀释血清的中和试验方法,对从我国浙江、江西、安徽和广东地区采集的外观健康鼬獾的215份血清进行了狂犬病中和抗体的检测。结果显示,鼬獾体内存在比例较高（38％）的狂犬病中和抗体,但是自不同地区或群体采集的血清样品,狂犬病中和抗体阳性率不同,有些群体样品中完全没有抗体,有些群体样品中狂犬病中和抗体阳性比例100％,但是中和抗体的水平普遍不高,说明鼬獾种群感染狂犬病几率较高,并可能存在狂犬病的一过性或隐性感染。     

Rabies surveillance in the United States during 2004

During 2004, 49 states and Puerto Rico reported 6,836 cases of rabies in nonhuman animals and 8 cases in human beings to the CDC, representing a 4.6% decrease from the 7,170 cases in nonhuman animals and 3 cases in human beings reported in 2003. Approximately 92% of the cases were in wildlife, and 8% were in domestic animals (compared with 91% and 9%, respectively, in 2003). Relative contributions by the major animal groups were as follows: 2,564 raccoons (37.5%), 1,856 skunks (27.1%), 1,361 bats (19.9%), 389 foxes (5.7%), 281 cats (4.1%), 115 cattle (1.7%), and 94 dogs (1.4%). Compared with the numbers of reported cases in 2003, cases in 2004 decreased among all groups, except bats, cattle, human beings, and "other domestics" (1 llama). Decreases in numbers of rabid raccoons during 2004 were reported by 12 of the 20 eastern states in which raccoon rabies was enzootic. In the East, Massachusetts reported the first cases of raccoon rabies detected beyond the Cape Cod oral rabies vaccine barrier. Along the western edge of the raccoon rabies epizootic (Ohio in the north and Tennessee in the south), cases of rabies were reported from unexpected new foci beyond oral rabies vaccine zones. On a national level, the number of rabies cases in skunks during 2004 decreased by 12.1% from the number reported in 2003. Once again, Texas reported the greatest number (n = 534) of rabid skunks and the greatest overall state total of rabies cases (913). Texas reported only 1 case of rabies in a dog that was infected with the dog/coyote rabies virus variant and only 22 cases associated with theTexas gray fox rabies virus variant (compared with 61 cases in 2003). The total number of cases of rabies reported nationally in foxes and raccoons declined 14.7% and 2.7%, respectively, during 2004. The 1,361 cases of rabies reported in bats during 2004 represented a 12.3% increase over the previous year's total of 1,212 cases for this group of mammals. Cases of rabies reported in cats, dogs, horses and mules, and sheep and goats decreased 12.5%, 19.7%, 31.8%, and 16.7%, respectively, whereas cases reported in cattle increased 174%. In Puerto Rico, reported cases of rabies in mongooses decreased 4.1% and rabies in dogs (9 cases) remained unchanged from those reported in 2003. Among the 8 cases of rabies in human beings, 1 person from Oklahoma and 3 from Texas died following receipt of infected organs and tissues from an Arkansas donor. In California, a person originally from El Salvador and, in Florida, a person originally from Haiti both died of canine rabies infections acquired outside the United States. In Wisconsin, a teenager contracted rabies from a bat bite and became the first known person to survive rabies despite not having received rabies vaccine prior to symptom onset.     

Molecular characterization of Korean rabies virus isolates

The nucleoprotein (N) and glycoprotein (G) of 11 Korean rabies virus (RABV) isolates collected from animals diagnosed with rabies between 2008 and 2009 were subjected to molecular and phylogenetic analyses. Six isolates originated from domestic animals (cattle and dogs) and five were obtained from wild free-ranging raccoon dogs. The similarities in the nucleotide sequences of the N gene among all Korean isolates ranged from 98.1 to 99.8%, while those of the G gene ranged from 97.9 to 99.3%. Based on the nucleotide analysis of the N and G genes, the Korean RABV isolates were confirmed as genotype I of Lyssavirus and classified into four distinct subgroups with high similarity. Phylogenetic analysis showed that the Korean isolates were most closely related to the non-Korean NeiMeng1025B and 857r strains, which were isolated from rabid raccoon dogs in Eastern China and Russia, respectively. These findings suggest that the Korean RABV isolates originated from a rabid raccoon dog in Northeastern Asia. Genetic analysis of the Korean RABV isolates revealed no substitutions at several antigenic sites, indicating that the isolates circulating in Korea may be pathogenic in several hosts.     

Rabies surveillance in the United States during 2002

During 2002, 49 states and Puerto Rico reported 7,967 cases of rabies in nonhuman animals and 3 cases in human beings to the Centers for Disease Control and Prevention, an increase of 7.2% from the 7,436 cases in non-human animals and 1 case in a human being reported in 2001. More than 92% (7,375 cases) were in wild animals, whereas 7.4% (592) were in domestic species (compared with 93.3% in wild animals and 6.7% in domestic species in 2001). Compared with cases reported in 2001, the numbers of cases reported in 2002 increased among all major reporting groups with the exception of swine and rodents and lagomorphs. The relative contributions of the major groups of animals were as follows: raccoons (36.3%; 2,891 cases), skunks (30.5%; 2,433), bats (17.2%; 1,373), foxes (6.4%; 508), cats (3.8%; 299), dogs (1.2%; 99), and cattle (1.5%; 116). Thirteen of the 19 states in which the raccoon-associated variant of the rabies virus has been enzootic reported increases in the numbers of rabid raccoons during 2002. Among those states that have engaged in wildlife rabies control programs, Ohio reported 1 case of raccoon rabies associated with the epizootic of rabies in raccoons and 1 case in an equid that was infected with a bat variant of the rabies virus, compared with 2 cases reported in terrestrial animals during 2001. Texas reported no cases of rabies associated with the dog/coyote variant of the rabies virus (compared with 1 case in 2001) and 65 cases associated with the gray fox variant of the virus (an increase of 225% from 20 cases reported in 2001). In Massachusetts and Rhode Island, states with enzootic raccoon rabies, reports of rabid skunks again exceeded those of rabid raccoons (the sixth consecutive year, although in Rhode Island, this difference decreased to only 7 more skunks than raccoons [38/31]). Tennessee reported a single case of raccoon rabies in a pet raccoon from the central part of the state; the captive animal had been transported toTennessee from northern Georgia. Nationally, the number of rabies cases in skunks during 2002 increased by 6.6% over those reported in 2001. Texas reported the greatest number (740) of rabid skunks and the greatest overall state total of rabies cases (1,049) during 2002. The 1,373 cases of rabies reported in bats during 2002 surpassed the previous year's record (1,281 cases) as the largest number of reported cases ever recorded for this group of mammals. Cases of rabies reported in cats (299), cattle (116), and dogs (99) increased by 10.7%, 41.5%, and 11.24%, respectively, from 2001 to 2002. Rabies among sheep and goats increased 400% from 3 cases in 2001 to 15 in 2002, and cases among horses and mules increased 13.7% (51 cases in 2001 to 58 in 2002). Reported cases of rabies in mongooses in Puerto Rico decreased 4.3% from the previous year (70 cases in 2001 to 67 cases in 2002), while cases of rabies in dogs increased 77% (13 to 14). California, Tennessee, and Iowa each reported a case of rabies in a human being during 2002. All cases of rabies in humans were the result of infection with bat variants of the rabies virus.     

Use of infrared thermography to detect signs of rabies infection in raccoons (Procyon lotor).

Infrared thermography was evaluated as a technique to determine if raccoons (Procyon lotor) experimentally infected with rabies virus could be differentiated from noninfected raccoons. Following a 10-day adjustment period, raccoons (n = 6) were infected with a virulent rabies street strain raccoon variant by injection into the masseter muscle at a dose of 2 x 10(4) tissue-culture infectious dose (TCID50) in 0.2 ml (n = 4) or 10(5) TCID50 in 1 ml (n = 2). Five of the six raccoons developed prodromal signs of rabies 17 to 22 days postinoculation (PI) and distinctive clinical signs of furious rabies between 19 and 24 days PI. At the time of euthanasia, which occurred 2 days after the onset of clinical signs of rabies, these five raccoons tested positive for rabies virus in brain tissue. Infrared thermal images of each raccoon were recorded twice daily during the preinoculation and PI periods. No apparent differences were identified among thermal temperatures compared among days for the eye, average body surface, and body temperature recorded from subcutaneous implants throughout the experiment for any of the six raccoons. However, increases in infrared surface temperature of the noses and differences in the visual thermal images of the noses were detected when animals began showing clinical signs of rabies. Differences were detected among the mean infrared nose temperatures for the disease progression intervals (F3.12 = 70.03, P < 0.0001). The mean nose temperature in the clinical rabies stage (30.4 +/- 3.5 degrees C) was significantly elevated over the prodromal stage (F1,12 = 151.85, P < 0.0001). This experiment provides data indicating that infrared thermography can be used in an experimental setting to detect raccoons in the infectious stage and capable of exhibiting clinical signs of rabies.     

Assessing a landscape barrier using genetic simulation modelling: implications for raccoon rabies management

Landscape barriers influence movement patterns of animals, which in turn, affect spatio-temporal spread of infectious wildlife disease. We compare genetic data from computer simulations to those acquired from field samples to measure the effect of a landscape barrier on raccoon (Procyon lotor) movement, enabling risk assessment of raccoon rabies disease spread across the Niagara River from New York State into Ontario, an area currently uninfected by rabies. An individual-based spatially explicit model is used to simulate the expansion of a raccoon population to cross the Niagara River, for different permeabilities of the river to raccoon crossings. Since the model records individual raccoon genetics, the genetic population structure of neutral mitochondrial DNA haplotypes are characterised in the expanding population, every 25 years, using a genetic distance measure, phi ST, Mantel tests and a gene diversity measure. The river barrier effect is assessed by comparing genetic measures computed from model outputs to those calculated from 166 raccoons recently sampled from the same landscape. The "best fit" between modelled scenarios and field data indicate the river prevents 50% of attempts to cross the river. Founder effects dominated the colonizing genetic population structure, and, as the river barrier effect increased, its genetic diversity decreased. Using gene flow to calibrate the effect of the river as a barrier to movement provides an estimate of the effect of a river in reducing the likelihood of cross-river infection. Including individual genetic markers in simulation modelling benefits investigations of disease spread and control.     

Rabies surveillance in the United States during 2007

SUMMARY: During 2007, 49 states and Puerto Rico reported 7,258 cases of rabies in animals and 1 case in a human to the CDC, representing a 4.6% increase from the 6,940 cases in animals and 3 cases in humans reported in 2006. Approximately 93% of the cases were in wildlife, and 7% were in domestic animals. Relative contributions by the major animal groups were as follows: 2,659 raccoons (36.6%), 1,973 bats (27.2%), 1,478 skunks (20.4%), 489 foxes (6.7%), 274 cats (3.8%), 93 dogs (1.3%), and 57 cattle (0.8%). Compared with numbers of reported cases in 2006, cases in 2007 increased among dogs, bats, foxes, and skunks while decreases were reported among cattle, cats, and skunks. Increases in numbers of rabid raccoons during 2007 were reported by 11 of the 20 eastern states where raccoon rabies was enzootic, and reported cases increased by 1.7% overall, compared with 2006. On a national level, the number of rabies cases in skunks during 2007 decreased by 1.1% from the number reported in 2006. Texas reported the greatest number (n = 362) of rabid skunks and the greatest overall state total of animal rabies cases (969). No cases of rabies associated with the dog/coyote rabies virus variant were reported. The United States remains free of dog-to-dog transmission of canine rabies virus variants. The total number of cases of rabies reported nationally in foxes increased 14.5%, compared with 2006. Increases in the number of reported rabid foxes were attributable to greater numbers of foxes reported with the Arctic fox rabies virus variant in Alaska, the Texas gray fox rabies virus variant in Texas, and the raccoon rabies virus variant in Virginia. The 1,973 cases of rabies reported in bats represented a 16.6% increase over numbers reported in 2006. Cases of rabies in dogs and in sheep and goats increased 17.7% and 18.2%, respectively, whereas cases reported in cattle, cats, and horses and mules decreased 30.5%, 13.8%, and 20.8%, respectively. In Puerto Rico, reported cases of rabies in mongooses decreased 51.5%, and rabies in domestic animals, presumably attributable to spillover infection from mongooses, increased 25%. One human rabies case was reported from Minnesota during 2007. Although typing of the rabies virus variant in this case was not possible, an investigation of this case indicated a bat as the most likely source of exposure.     

Prevalence and intensity of Echinococcus multilocularis in red foxes (Vulpes vulpes schrencki) and raccoon dogs (Nyctereutes procyonoides albus) in Otaru City, Hokkaido, Japan

A survey was done in an attempt to investigate the epidemiological status of Echinococcus multilocularis in red foxes and raccoon dogs in Otaru city from June to September 1999. Sixty-seven red foxes (Vulpes vulpes schrencki) and 13 raccoon dogs (Nyctereutes procyonoides albus) were captured, and postmortem examinations were conducted with them. Thirty-eight red foxes (56.7%) and 3 raccoon dogs (23.1%) were found to be infected with E. multilocularis. The total biomass of E. multilocularis in all infected red foxes and raccoon dogs were 2,817,000 and 1,515 worms, respectively. Nine of the infected red foxes harboring more than 100,000 worms accounted for 90.6% of the total biomass. No significant differences in the prevalence were observed between male and female, and juvenile and adult. However, the worm burden was higher in juvenile than in adult foxes. In one of the infected raccoon dogs, mature worms and eggs of E. multilocularis were found in the intestine and fecal sample, respectively. This result suggested that the raccoon dogs are probably playing a small role in the egg contamination of the environment. The validity of coproantigen ELISA for diagnosis of foxes was confirmed by comparing the results of autopsy, egg examination and coproantigen ELISA using rectal fecal samples.     

Estimating the incubation period of raccoon rabies: a time-space clustering approach

We used a time-space clustering approach to estimate the incubation period of raccoon rabies in the wild using data from the 1999-2001 invasion of raccoon rabies into eastern Ontario from northern New York State. The time differences and geographical distances between all possible pairs of rabies cases were computed, classified and assembled into a time-space matrix. The rows of that matrix represented differences in cases in weeks and the columns represent distances between cases in kilometers and the values in the cells of the matrix represent the counts of cases at specific time and distance intervals. There was a significant cluster of pairs 5 weeks apart with apparent harmonics at additional 5-week intervals. These results are explained by assuming the incubation period of raccoon rabies had a mode of 5 weeks. The time clusters appeared consistently at distance intervals of 5 km. We discuss the possibility that the spatial intervals were influenced by the 5 km radius of the point infection control depopulation process used in 1999 and the 10-15 km radial areas used in 2000. With the practical limits of those radii, there was an intensive effort to eliminate raccoons. Our procedure is easy to implement and provides an estimate of the shape of the distribution of incubation periods for raccoon rabies.