Epidemiological studies on the background of the endemic occurrence of tsutsugamushi disease in Toyama Prefecture. I. Epidemiology of infection with Rickettsia tsutsugamuchi among field rodents in endemic and nonendemic areas

In order to clarify the epidemiological background of the endemic occurrence of tsutsugamushi disease in Toyama Prefecture, Japan, since 1978, comparative surveys have been carried out between endemic and nonendemic areas. Rickettsia tsutsugamushi (Rt) was isolated at a rate of about 36% (158/439) from field rodents in the endemic area while it was not isolated from any of 280 in nonendemic areas. In all of six stations in the endemic area, a significantly high proportion of rodents were found to be Rt carriers. However, no Rt was isolated from rodents captured from July to September. The organism was isolated from rodents captured in the other months, especially in a high proportion in November when infestation of rodents with Leptotrombidium pallidum was at its peak. When the rodents were examined by indirect immunofluorescence staining, the rate of anti-Rt antibody-positive animals was about 55% (157/287) and about 17% (62/368) in endemic and nonendemic areas, respectively. Larvae of mites collected from the rodents were found to belong to four genera and 11 species. Among them L. pallidum was the only mite that had been known to be a vector of Rt. L. pallidum was found most frequently and in abundance from rodents in the endemic area, whereas it was present in very small numbers in rodents in nonendemic areas. The infestation of rodents with L. pallidum showed a seasonal variation, i.e. two peaks per year, in spring and autumn, and the number of mites detected was markedly greater in November than in spring. Rt was isolated from L. pallidum on rodents captured in the endemic area.     

Epidemiological studies on echovirus type 18 infection in Toyama Prefecture

Echovirus type 18 (echo 18) was isolated from six aseptic meningitis children in Fukumitsu-machi, Toyama Prefecture, from July to August, 1980. This was the first virologically-confirmed epidemic of aseptic meningitis due to echo 18 in Japan. Epidemiological studies on the prevalence of this virus among the inhabitants in Toyama Prefecture were also performed. The results are summarized as follows. (1) Significant increases in neutralizing antibody titers against echo 18 were observed in all the paired sera of aseptic meningitis patients from whom echo 18 was isolated. (2) In October, 1980, echo 18 was also isolated from healthy children or from infants suffering from gastroenteritis in other areas of Toyama Prefecture. (3) Among the sera collected from 50 children (aged smaller than or equal to 12) in Fukumitsumachi in December, 1980, neutralizing antibodies against echo 18 were detected only in the younger groups (aged smaller than or equal to 8), 58.9% of these age groups showing a titer of 4 or higher. (4) Another epidemic around 1963 by echo 18 in Toyama Prefecture was retrospectively suggested by the examinations of sera collected in 1978 and 1981 from inhabitants in various areas of Toyama Prefecture. (5) Neutralizing antibody titers against the strain isolated, No. 35'80, were significantly higher than those against strain 'Metcalf,' the prototype of echo 18, in most sera including both aseptic meningitis patients and healthy inhabitants.     

Epidemiological studies on host animals of tsutsugamushi disease in Korea

Epidemiological studies on host rodents of tsutsugamushi disease were carried out during the period of July-September 1990 at nine localities of central Korea. Among total 111 wild rodents trapped by the modified Sherman live traps, 103 were Apodemus agrarius (92.8%), seven were Crocidura lasiura (6.3%) and one was Microtus fortis (0.9%), showing 24.0% of trapping rate in winter, 11.7% in spring, 11.2% in summer and 12.0% in autumn. Out of 103 A. agrarius 84 were parasitized by chiggers, showing 81.6% of the infestation rate and 43.0 of the chigger index. The antibody positive rate of A. agrarius sera to Rickettsia tsutsugamushi was significantly variable by locality, being in the range of 0-78.6%. The seasonal change of the antibody positive rate at Dorai 5-ri, Goyang-gun was 75.8% in average during November-March, decreased to 30.3% in April and further decreased to 13.3% in average during May-August. Among 33 antibody positives, 31 were Karp strain and two were Gilliam. Seven Crocidura lasiura sera showed all negative. R. tsutsugamushi organisms were isolated from three A. agrarius out of 94 mice tested, showing 3.2% of the infection rate.     

Ecological studies on reovirus pollution of rivers in Toyama Prefecture

Reoviruses (reos) were isolated from river water in various areas of Toyama Prefecture. The frequency of reo isolation was higher in the river water, the basin of which has a larger human population. The degree of river contamination with reo paralleled that with the Escherichia coli group of organisms, and reos were frequently isolated from sewage, too. The high antibody-positive (greater than or equal to 1:8 or greater than or equal to 1:10) rates against reos in humans and other animals tested (swine, cattle, and field rodents) indicated their wide-spread infection with reos. These results suggested that the major source of reos present in the river water may be the excretion by humans and other animals, especially the former. Survival experiments in which reos were added into the filtered or centrifuged river water and kept at various temperatures, revealed that reos survived for more than 3 years at 5 C. In the field experiment where reos suspended in cellophane tubes were kept in an agricultural water stream in winter (water temperatures below 10 C), they survived for 6 months until the water temperature rose above 20 C in summer.     

Ecological Studies on Reovirus Pollution of Rivers in Toyama Prefecture. II. Molecular Epidemiological Study of Reoviruses Isolated from River Water

In order to clarify the source of reovirus pollution in river water, comparative surveys have been carried out between reovirus isolates from river water and those from sewage, human or animal, by making use of the analysis of genomic RNA-migration pattern of reovirus in polyacrylamide gel electrophoresis (electropherotype). The strains of reovirus serotype 1 and 2 isolated from river water were classified into 3 and 9 electropherotypes, respectively, and 8 out of these 12 types were also found among strains isolated from sewage or human. When the monthly distribution of the river isolates classified by electropherotypes was compared with that of the sewage isolates, there were cases in which strains of the same electropherotype were simultaneously isolated from both sources. The electropherotypes of 3 isolates from pig and field rodents were different from those of the other isolates. The electropherotype of an oyster isolate coincided with that of some of the isolates from humans and river water. These results indicate that the major sources of reoviruses polluting river water may be the human excretion.     

Epidemiological status of Chagas disease in the endemic area from Region II of Antofagasta]

During 1997 a seroepidemiological study on Chagas' disease was carried out in 18 localities of three provinces (Tocopilla, El Loa and Antofagasta) of Region II (20 degrees 56'-26 degrees South Lat.; 70 degrees 38'-67 degrees West Long.), in order to assess the impact of the control program against Triatoma infestans launched in 1988, based on insecticide spraying of dwellings. By means of ELISA and an indirect hemagglutination test for Chagas' disease blood samples from 1,034 children under 10 years of age were examined, arising a 0.5% (3 cases) positivity. Test resulted positive in 2 (0.9%) children from the locality of San Pedro de Atacama and 1 (0.4%) from Calama city, all in the age group 6-10 year-old. However, none of their dwellings were found infested with T. infestants. These results indicate that the control program has a good possibility to prevent new human infections. It is advisable to continue the seroepidemiological and entomological vigilance and remark the necessity of increasing the effort in the study of transmission through other routes, to adopt or reinforce the pertinent preventive measures.     

Epidemiological characteristics of tsutsugamushi disease in Oita Prefecture, Japan: yearly and monthly occurrences of its infections and serotypes of its causative agent, Orientia tsutsugamushi, during 1984--2005.

Using indirect immunofluorescence assay, we examined the sera of 561 patients from November 1984 to February 2005 to determine the incidence of tsutsugamushi disease (scrub typhus) in Oita Prefecture, Japan. The results obtained were positive in 384 individuals (68.4%). Municipalities where patients were presumed to have been infected with Orientia tsutsugamushi were Taketa City (41.7%), Oyama Town (13.5%), and Ogi Town (8.3%). Infections occurred most often in October, November, and December. A small number of cases occurred from January to May. The serotypes Kuroki (47.5%), Kawasaki (42.5%), and Karp (10.0%) were detected by genetic analysis of O. tsutsugamushi DNA extracted from the blood of 120 patients. The gene sequences of the Kuroki type were highly homologous to that of the Nishino strain. The gene sequences of the Kawasaki type were identical to that of the Kawasaki strain. The gene sequence of the Karp type was highly homologous to that of the JP-2 type. To determine the distribution of vector mites, 558 wild rodents were captured and 72010 mites attached to these rodents were collected from 1982 to 1998. Six genera and 16 species of trombiculid mites were collected. Leptotrombidium pallidum and L. scutellare, which are known to be mite vectors for tsutsugamushi disease, accounted for 20.5% and 5.9%, respectively, of all trombiculid mites collected. The geographical distribution of cases roughly coincided with the distribution of L. scutellare. In Oita Prefecture, L. scutellare is presumed to primarily transmit tsutsugamushi disease. In addition, our results also suggest that L. pallidum transmits the Karp type of the causative rickettsia in some municipalities.     

Epidemiological characteristics of tsutsugamushi disease in Oita Prefecture, Japan: Yearly and monthly occurrences of its infections and serotypes of its causative agent, Orientia tsutsugamushi, during 1984–2005

Using indirect immunofluorescence assay, we examined the sera of 561 patients from November 1984 to February 2005 to determine the incidence of tsutsugamushi disease (scrub typhus) in Oita Prefecture, Japan. The results obtained were positive in 384 individuals (68.4%). Municipalities where patients were presumed to have been infected with Orientia tsutsugamushi were Taketa City (41.7%), Oyama Town (13.5%), and Ogi Town (8.3%). Infections occurred most often in October, November, and December. A small number of cases occurred from January to May. The serotypes Kuroki (47.5%), Kawasaki (42.5%), and Karp (10.0%) were detected by genetic analysis of O. tsutsugamushi DNA extracted from the blood of 120 patients. The gene sequences of the Kuroki type were highly homologous to that of the Nishino strain. The gene sequences of the Kawasaki type were identical to that of the Kawasaki strain. The gene sequence of the Karp type was highly homologous to that of the JP-2 type. To determine the distribution of vector mites, 558 wild rodents were captured and 72 010 mites attached to these rodents were collected from 1982 to 1998. Six genera and 16 species of trombiculid mites were collected. Leptotrombidium pallidum and L. scutellare , which are known to be mite vectors for tsutsugamushi disease, accounted for 20.5% and 5.9%, respectively, of all trombiculid mites collected. The geographical distribution of cases roughly coincided with the distribution of L. scutellare . In Oita Prefecture, L. scutellare is presumed to primarily transmit tsutsugamushi disease. In addition, our results also suggest that L. pallidum transmits the Karp type of the causative rickettsia in some municipalities.     

Epidemiological and linkage studies on Huntington's disease in Italy

Summary The results of an epidemiological survey on Huntington's disease in the Lazio Region, Central Italy, and of linkage studies in a subset of families are reported. From a total of 99 ascertained families and 491 patients, a prevalence of 25.6 × 10–6 was obtained, with distributions of age at onset and age at death similar to those described in the literature. No relationship with the sex of the transmitting parent was observed. Analysis of 10 chromosome 4 restriction fragment length polymorphisms in 11 families showed consistent linkage between the genetic loci D4S10, D4S43 and D4S95, and the disease. A recombination rate of 0.08 for D4S10 markers was obtained in this sample. Allelic frequencies of DNA markers in the general population are also reported.     

Epidemiological survey of Orientia tsutsugamushi distribution in field rodents in Saitama Prefecture, Japan, and discovery of a new type

There are various antigenic variants of Orientia tsutsugamushi which are distinguished by immunological and molecular genetic methods targeted at the antigenic diversity of 56-kDa type-specific antigen proteins. The present study was performed to analyze 15 strains successfully isolated from rodents in Saitama Prefecture, Japan, by 56-kDa gene sequence homologies, reactivities with type-specific monoclonal antibodies and polymerase chain reaction (PCR) using type-specific primer-pairs. We demonstrated the presence of a new type of O. tsutsugamushi among the isolates. This new type, designated as the Saitama type, was located in the branch of Karp type in the phylogenetic tree based on 56-kDa gene sequences, but distant from the known Karp types, such as Karp, JP-1 and JP-2, showing less than 90% homology. Strains of this type could not be distinguished by immunological methods from Karp type strains, but a new primer-pair for PCR which specifically amplifies the DNA of this new type strain was designed. This primer-pair may serve to find this strain type in future studies.     

Epidemiological studies on the stunt disease of highbush blueberry

Population levels of Scaphytopius spp., possible sharpnosed leafhopper vectors of blueberry stunt disease (BBSD), were monitored during 1989,1990 and 1991, using yellow sticky traps and a D-Vac power aspirator. Scaphytopius magdalensis (Prov.), S. frontalis (Van D.) and 5. acutus (Say) had two population peaks, one after the petal fall stage and a larger second peak in late Summer to early Autumn. Healthy cv. Bluecrop highbush blueberry (Vaccinium corymbosum L.) plants were placed under stunt-diseased bushes in the field for 2-wk periods during 1989 and 1990. These plants and some of the leafhoppers trapped during 1990 and 1991 were tested for mycoplasma-like organism (MLO) infection with a DNA probe that detected BBSD-associated MLO. The percentage of plants and the number of Scaphytopius spp. that were MLO-positive tended to follow the same bimodal distribution found in the population studies. BBSD transmission tests were performed with Scaphytopius spp. collected from the field. Stunt-related MLO transmission was achieved with S. magdalensis, S. acutus and 5. frontalis.     

Roadblocks in Chagas disease care in endemic and nonendemic countries: Argentina,Colombia, Spain,and the United States. The NET-Heart project

BackgroundChagas disease (CD) is endemic in Latin America; however, its spread to nontropical areas has raised global interest in this condition. Barriers in access to early diagnosis and treatment of both acute and chronic infection and their complications have led to an increasing disease burden outside of Latin America. Our goal was to identify those barriers and to perform an additional analysis of them based on the Inter American Society of Cardiology (SIAC) and the World Heart Federation (WHF) Chagas Roadmap, at a country level in Argentina, Colombia, Spain, and the United States, which serve as representatives of endemic and nonendemic countries.Methodology and principal findingsThis is a nonsystematic review of articles published in indexed journals from 1955 to 2021 and of gray literature (local health organizations guidelines, local policies, blogs, and media). We classified barriers to access care as (i) existing difficulties limiting healthcare access; (ii) lack of awareness about CD and its complications; (iii) poor transmission control (vectorial and nonvectorial); (iv) scarce availability of antitrypanosomal drugs; and (v) cultural beliefs and stigma. Region-specific barriers may limit the implementation of roadmaps and require the application of tailored strategies to improve access to appropriate care.ConclusionsMultiple barriers negatively impact the prognosis of CD. Identification of these roadblocks both nationally and globally is important to guide development of appropriate policies and public health programs to reduce the global burden of this disease.     

Pilot studies on the occurrence of some infectious diseases in two different areas in south Yemen (Aden) (part II. Microbiology).

This paper is the second part of the article dealing with intestinal bacteria. The findings are relatively poor in comparing with the frequency of intestinal protozoa. Among 83 stool specimens taken for bacteriological examination 14 isolations of different bacteria were proved. One S. muenchen was isolated from a 3 year old boy with fever, diarrhoea. Five cases of Alkalescens dispar 05 manit negative and 05 manit positive were identified. Two of these cases were without clinical symptoms. All were males aged 10-17 years. One isolation of E. coli EPEC 086 K6 H11 was in a 10 year-old boy with diarrhoea, four watery stools daily and cramps. Six cases of other E. coli were of different types, all with clinical symptoms. Of them three were males and three females at the age from 3-46 years. One case had a mixed infection of Citrobacter, E. coli and Klebsiella with diarrhoea, about 5 watery stools daily and abdominal pain. The frequency of intestinal bacteria in males was nearly three times higher than in females. The occurrence in age groups 10-20 was almost equal 20.0-22.2%, in 0-4 it was 42.9% and surprisingly low in 5-9 years old--3.4% only.     

Spatial variation in abundance of the junin virus hosts in endemic and nonendemic Argentine haemorrhagic fever zones

Abstract Argentine haemorrhagic fever (AHF) is caused by Junin (JUN) virus, which is hosted by the drylands vesper mouse (Calomys musculinus). In this work we monitored population abundance of C. musculinus and rodent assemblages for 3 years in and outside the AHF endemic zones (northern Buenos Aires, southern Córdoba and Santa Fe Provinces, Argentina). The study area was divided into endemic and nonendemic zones. In the endemic zone epidemic sites were recognized, characterized by recent emergence and maintenance of AHF cases, and also historical sites, characterized by decreased incidence or disappearance of AHF human cases. In the nonendemic zone AHF has never been recognized. Although differences were statistically significant only during some periods, population abundance of C. musculinus was usually lower in the nonendemic sites. The pattern and magnitude of seasonal fluctuations in C. musculinus populations were also distinct in the nonendemic sites as compared to endemic sites. The relative abundance of C. musculinus in rodent assemblage was lower in nonendemic sites than in the endemic sites. The lower population densities and dampened seasonal dynamics may be at least partly responsible for the absence of AHF cases in the nonendemic zone. It is suggested that the balance between intra and interspecific interactions might be the cause of the pattern of incidence and prevalence of pathogens in the host species.     

Studies on the enteropathogenic mechanism of non-O 1 Vibrio cholerae isolated from the environment and fish in Toyama Prefecture

Enteropathogenic mechanisms of non-O 1 Vibrio cholerae were investigated using strains from the environment and those from fish in Toyama Prefecture. None of the 93 non-O 1 V. cholerae strains produced a detectable level of choleratoxin-like-enterotoxin (CT-like-enterotoxin) in Syncase medium, while 23 strains showed a distinct fluid accumulation in the rabbit ileal loop test (RIL). These RIL-positive strains neither produced CT-like-enterotoxin in vitro in the other four kinds of media which are considered suitable for CT production, nor in vivo in the ligated ileal loop. Approximately one-third of RIL-positive strains produced a fluid accumulating factor (FAF) which was not neutralized with anti-CT serum. FAF of a representative strain (Strain 79-9-2) was inactivated by heating at 100 C for 10 min, and has a molecular weight within the range of 50,000 to 100,000 daltons. Most accumulated fluids in RIL after inoculation with whole cultures of RIL-positive strains contained both hemolytic and cytotoxic principles. Desquamation of epithelial cells, inflammatory edema, neutrophile infiltration, loss of goblet cells and frequent hemorrhages were observed in sections of ligated ileal loop inoculated with whole cultures or concentrated culture filtrates of CT-like-enterotoxin-negative but RIL-positive strains. In contrast, neither desquamation of epithelial cells nor hemorrhage was observed in sections after inoculation with those of a CT-like-enterotoxin positive strain (Strain E 8498). These results indicated that most RIL-positive non-O 1 V. cholerae strains from the environment and fish isolated in Toyama Prefecture produce little CT-like-enterotoxin, but some of them produce FAF with cytotoxic activities.     

高寒民族地区居民的旅游支持度及影响因素——以甘南藏族自治州为例

旅游业是当前高寒民族地区实现乡村振兴的重要举措,辨明居民的旅游支持度及其影响因素有利于精准制定旅游发展政策。以甘南藏族自治州为研究区,突出该区民族文化特征,建立了以文化整合、地方感、旅游机构信任、旅游事件依恋为自变量的居民旅游支持度模型,并分析了影响该区居民旅游支持度的关键因素。结果表明:(1)藏族居民旅游支持度最高,回族次之,汉族最低;牧民、僧侣、家庭主妇、学生、私营业主、公务员的旅游支持度呈递减趋势;"易地搬迁型"乡村社区居民旅游支持度最高,"民宿开发型"次之,"寺院景区门户型"社区居中,"寺院僧舍型"社区较低,"景区边缘型"社区最低。(2)旅游收益感知对居民旅游支持度产生积极影响,旅游成本感知对居民旅游支持度产生负向影响;居民对旅游机构的信任与居民对旅游事件依恋均对旅游收益感知产生积极影响、对旅游成本感知产生负向影响,从而影响居民旅游支持度;文化整合与居民对旅游事件依恋除对旅游支持度产生直接影响外,还通过增强旅游收益感知、降低旅游成本感知而对旅游支持度产生显著正向作用。