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1.
Epidemiology of trichinellosis in Mexico, Central and South America   总被引:6,自引:0,他引:6  
Trichinella species are widely distributed throughout the world and are found in a large number of carnivorous animals, humans and incidental hosts. The data presented in this review show that Trichinella infection has been reported in both humans and animals in Mexico, Argentina and Chile since the end of the 19th century, and more recently in Bolivia. This parasitic infection is still a public health problem in countries such as Argentina and Chile. Although efforts have focused on the control and prevention of trichinellosis in these countries, there were still human cases and outbreaks of trichinellosis reported. Diagnosis of infection in animals such as pigs still includes, in many endemic areas, the use of trichinoscopy. In Argentina, however, artificial digestion has been recently introduced in slaughterhouses to detect Trichinella infection in pigs. In some endemic areas in Mexico, the use of serological assays for human trichinellosis and pig infections have resulted in improved detection. Most of the outbreaks of human trichinellosis in Mexico, Argentina and Chile have occurred as a result of the consumption of undercooked pork or pork products from animals raised under poor hygienic conditions and which are clandestinely slaughtered. In several studies, rats, dogs and cats have been found to be infected with Trichinella and may be considered a risk for transmission of the infection to pigs or other animals intended for human consumption. Another potential source of transmission of Trichinella to humans is horsemeat; however, information related to horse trichinellosis in Latin-American countries is scarce. In most cases the etiological agent of human trichinellosis in Central and South America has been reported to be Trichinella spiralis; however, only in a few cases has the parasite species been properly identified. Based on the reports available, it is clear that there is a need to carry out better controlled epidemiological studies to determine the true prevalence of the infection in this region of the world. Also, more sensitive methods of diagnosis and improvements in conditions for pig production as well as better sanitary inspection systems, are needed for controlling and preventing transmission of trichinellosis in these countries.  相似文献   

2.
New patterns of Trichinella infection   总被引:3,自引:0,他引:3  
Human and animal trichinellosis should be considered as both an emerging and reemerging disease. The reemergence of the domestic cycle has been due to an increased prevalence of Trichinella spiralis, which has been primarily related to a breakdown of government veterinary services and state farms (e.g., in countries of the former USSR, Bulgaria, Romania), economic problems and war (e.g., in countries of the former Yugoslavia), resulting in a sharp increase in the occurrence of this infection in swine herds in the 1990s, with a prevalence of up to 50% in villages in Byelorussia, Croatia, Latvia, Lithuania, Romania, Russia, Serbia, and the Ukraine, among other countries. The prevalence has also increased following an increase in the number of small farms (Argentina, China, Mexico, etc.) and due to the general belief that trichinellosis was a problem only until the 1960s. The sylvatic cycle has been studied in depth at both the epidemiological and biological level, showing the existence of different etiological agents (Trichinella nativa, Trichinella britovi, Trichinella murrelli, Trichinella nelsoni) in different regions and the existence of "new" transmission patterns. Furthermore, the role of game animals as a source of infection for humans has greatly increased both in developed and developing countries (Bulgaria, Canada, Lithuania, some EU countries, Russia, USA, etc.). The new emerging patterns are related to non-encapsulated species of Trichinella (Trichinella pseudospiralis, Trichinella papuae, Trichinella sp.), infecting a wide spectrum of hosts (humans, mammals including marsupials, birds and crocodiles) and to encapsulated species (T. spiralis, T. britovi, and T. murrelli) infecting herbivores (mainly horses). The existence of non-encapsulated species infecting mammals, birds and crocodiles had probably remained unknown because of the difficulties in detecting larvae in muscle tissues and for the lack of knowledge on the role of birds and crocodiles as a reservoir of Trichinella. On the other hand, it is not known whether horse and crocodile infections existed in the past, and their occurrence has been related to improper human behavior in breeding. The problem of horse-meat trichinellosis is restricted to France and Italy, the only two countries where horse-meat is eaten raw, whereas mutton and beef have been found to be infected with Trichinella sp. only in China.  相似文献   

3.
The epidemiology of animal trichinellosis in China   总被引:2,自引:0,他引:2  
The epidemiology of animal trichinellosis in China based mainly upon original Chinese literature published between 1937 and 2004 is reviewed. The seroprevalence of Trichinella infection in herbivores was 0.7% (2/300) in cattle and 0.8% (4/500) in sheep. The prevalence of trichinellosis in naturally infected cattle was 1.2% (2/163). Trichinella larvae were detected in 1.4% (3/215) of sheep and in 2.1% (1/47) of beef cattle sold at markets. Canine trichinellosis was recorded in 13 Provinces, Autonomous Regions or Municipalities (P/A/M) and the average prevalence of the infection in dogs slaughtered in abattoirs was 16.2% (5654/34,983) ranging from 1.2% to 44.8%, with the highest prevalence located in northeast China. The prevalence in dog meat sold at markets was 3.5% (988/27,898) in 5 P/A. Feline Trichinella infection was reported in 10 P/A/M. The prevalence of Trichinella infection in rats varied from 1.1% (51/459) to 15.1% (50/332). Trichinella larvae were detected in 1.5% (9/587) of house rats (Rattus norvegicus) as well as in 0.8% (3/369) of wild rats (Apodemus chevrieri), and the infection was recorded also in other wildlife (foxes, bears, wild boar, weasels, raccoon dogs, muntjak and bamboo rats). Trichinella larvae were detected in 2.6% (4/156) of weasels (Mustela sibirica), 1.5% (2/135) of shrews (Tupaia belangeri) and 7.7% (1/13) of moles (Parascapter leucurus). All Trichinella isolates from domestic pigs were identified as T. spiralis. Some Trichinella isolates from dogs in north-eastern China were identified as T. nativa, which has muscle larvae that are highly resistant to freezing. Twenty-seven outbreaks of human trichinellosis associated with mutton, dog and game meat occurred in China between 1964 and 2004, but the quarantine of Trichinella larvae in such meat is not mandatory in China at present.  相似文献   

4.
World distribution of Trichinella spp. infections in animals and humans   总被引:5,自引:0,他引:5  
The etiological agents of human trichinellosis show virtually worldwide distribution in domestic and/or wild animals, with the exception of Antarctica, where the presence of the parasite has not been reported. This global distribution of Trichinella and varying cultural eating habits represent the main factors favouring human infections in industrialised and non-industrialised countries. Human trichinellosis has been documented in 55 (27.8%) countries around the world. In several of these countries, however, trichinellosis affects only ethnic minorities and tourists because the native inhabitants do not consume uncooked meat or meat of some animal species. Trichinella sp. infection has been documented in domestic animals (mainly pigs) and in wildlife of 43 (21.9%) and 66 (33.3%) countries, respectively. Of the 198 countries of the world, approximately 40 (20%) are small islands far from the major continents, or city-states where Trichinella sp. cannot circulate among animals for lack of local fauna (both domestic and wild). Finally, information on the occurrence of Trichinella sp. infection in domestic and/or wildlife is still lacking for 92 countries.  相似文献   

5.
In Argentina, there are three known species of genus Trichinella; however, Trichinella spiralis is most commonly associated with domestic pigs and it is recognized as the main cause of human trichinellosis by the consumption of products made with raw or insufficiently cooked pork meat. In some areas of Argentina, this disease is endemic and it is thus necessary to develop a more effective programme of prevention and control. Here, we developed a quantitative risk assessment of human trichinellosis following pork meat sausage consumption, which may be used to identify the stages with greater impact on the probability of acquiring the disease. The quantitative model was designed to describe the conditions in which the meat is produced, processed, transported, stored, sold and consumed in Argentina. The model predicted a risk of human trichinellosis of 4.88 × 10?6 and an estimated annual number of trichinellosis cases of 109. The risk of human trichinellosis was sensitive to the number of Trichinella larvae that effectively survived the storage period (r = 0.89), the average probability of infection (PPinf) (r = 0.44) and the storage time (Storage) (r = 0.08). This model allowed assessing the impact of different factors influencing the risk of acquiring trichinellosis. The model may thus help to select possible strategies to reduce the risk in the chain of by‐products of pork production.  相似文献   

6.
The zoonotic disease trichinellosis is considered one of the re-emerging diseases with surveillance and control methods constantly gaining more importance worldwide. Recent change in European Union (EU) legislation introduces Trichinella-free production, and the possibility of risk-based monitoring for Trichinella in pigs. This has increased the role of wildlife surveillance programmes and their impact on protecting human health as well as highlighted the need for harmonised surveillance protocols and test methods for these infections. A modified digest method, based on the EU reference method for Trichinella testing of pig meat, was used to screen foxes present in Great Britain (England, Scotland and Wales) for trichinellosis. The method was validated using batched pools of 10 g foreleg muscle from up to 20 foxes (maximum amount 200 g). The method gave an average trichinae recovery rate of 71% for spiked samples. Assuming this recovery rate applies to all contaminated samples, then the test sensitivity would be 70% for all tissue samples with 0.1 trichinae per 10 g of foreleg muscle, 99.9% for samples with 1 trichinae per 10 g, and 100% for samples with 2 or more trichinae per 10 g. In two separate studies, conducted between 1999 to 2001 (Smith et al., 2003) and 2003 to 2007, over 3500 wild foxes have been screened for Trichinella with negative results. In the second study reported here, foxes were collected from locations throughout Great Britain using a stratified sampling method based on fox population densities. All work was conducted in compliance with appropriate quality assurance systems, latterly under ISO 9001. Results to date indicate the national prevalence of trichinellosis in foxes is <0.001 based on a 10 g individual sample size, an infection level of 1 larva per gram (l pg) and 95% confidence interval. This, together with no reports of trichinellosis in domesticated pigs, suggests that Britain can be considered a region of negligible risk of trichinellosis.  相似文献   

7.
The prevention of human trichinellosis by proper meat inspection is a classic example of successful veterinary public health measures. The microscopic methods which have been used for more than a century to test pigs for trichinae were intended to prevent human disease. However, the value of these relatively insensitive direct detection methods, including trichinoscopy and pooled sample digestion, was debated as soon as more sensitive indirect (serological) methods became available. Two issues related to testing were discussed. First, should public health authorities endeavour to prevent all infections of humans rather than simply prevent the occurrence of disease, and second, would epidemiological surveillance and monitoring of the pig population on farms not provide a better control system to prevent human infection. This latter issue is of particular importance for those countries in the world where human trichinellosis acquired from farmed animals is absent and examination of pigs at the abattoir only results in negative findings. In countries where domestic pig infections are virtually non-existent, monitoring of Trichinella infection in wildlife could also contribute to understanding the infection pressure from nature to livestock. Trichinella-free pig farming is a feasible option for controlling this zoonosis, even in endemic areas. This approach provides an opportunity to combine good veterinary practice, in order to prevent animal diseases, with the prevention of Trichinella infection. All animals with access to the environment, or animals which are fed with potentially Trichinella-infected feed (swill, carcasses) will always constitute a public health threat, and must be inspected individually at slaughter (swine, horses, wild boars). Finally, it is important to recognize that trichinellosis is a world-wide problem that needs continuous public health attention. If no control system exists, for whatever reason, the public should be educated not to consume improperly cooked meat.  相似文献   

8.
The aim of the present work was to determine the presence of human and porcine trichinellosis in an area of Argentina historically regarded as Trichinella-free. Human blood donors (n = 216) and swine destined for consumption (n = 57) were evaluated by serological techniques (ELISA, immunofluorescence, and/or Western Blot). Muscle tissues from 26 of the pigs were evaluated for the presence of Trichinella larvae by the artificial digestion method. A questionnaire was used to collect and evaluate data on eating habits of the human population under study and on swine-raising conditions. The survey showed that 98.1% of the individuals (n = 212) were regular consumers of pork in the form of stuffed products such as sausages produced by local butchers. The seroprevalence (positive sera by at least two of the three methods) was 8.3% (n = 18) for human trichinellosis and 24.5% (n = 14) for porcine trichinellosis. Trichinella spiralis larvae were found in 2 of the 26 pigs (7.7%) with parasite loads of 0.33 and 2.4 muscle larvae per gram. Twelve swine found positive by serological and/or parasitological tests were raised under poor sanitary conditions (presence of rubbish in the surroundings, with cannibalism and scavenging behaviors, presence of rodents, etc.). Our study confirms the existence of porcine trichinellosis in an area regarded as Trichinella-free, provides supporting serological evidence of human infection in this area, and indicates that failure to report cases of trichinellosis based on inadequate surveillance can result in incorrect prevalence classification of an area.  相似文献   

9.
Recently, there has been interest in programs that certify pork production practices that minimize the risk of exposure of pigs to Trichinella spiralis. Certification might be useful for reducing the risk of human trichinellosis from pork in Argentina, but more information is needed on pig production practices and sources of Trichinella infection in Argentinian pigs. In this study, 21 pig farms were assessed for Trichinella infection including some farms using total and partial confinement management, and others with pigs raised exclusively outdoors. A total of 3224 muscle samples were collected from pigs raised on these farms and tested to determine the presence of T. spiralis larvae by artificial digestion. Serum samples from the same 3224 pigs were tested for antibodies to T. spiralis by ELISA. For each farm, a questionnaire was completed summarizing information about management factors and this information was used to assess risk factors for exposure of T. spiralis. Based on the results, pigs raised outdoors were more likely to be infected than pigs raised in total or partial confinement (p  0.05). Pigs fed waste products containing meat were 12.5 times more likely to be infected than pigs not fed waste containing meat (p < 0.01). The role played by rats in transmission of Trichinella is unclear; however, on farms with evidence of wild animals and access of pigs to wildlife carcasses, the prevalence of Trichinella infection was significantly higher. All pigs raised under good hygienic and sanitary conditions were negative for Trichinella infection by both artificial digestion and ELISA.  相似文献   

10.
The main source of trichinellosis in Romania is insufficiently cooked pork infected with Trichinella spiralis. Timis, the largest Romanian county, is located in the western part of the country where pork and traditional food prepared from pork are extensively consumed. The objective of the present study was to conduct a retrospective investigation of the incidence of human trichinellosis in Timis County over a period of 16 years (1990–2005). The medical records of 521 patients were used as the source of data. Patients were hospitalized at “Victor Babes” Hospital of Infectious Diseases from Timisoara during the period 1990–2005. The highest number of cases was recorded in 1994 (16.90%) and most of the patients were in the age group of 20–29 (23.22%). Males and females were almost equally affected by trichinellosis. The clinical pattern was mainly characterised by myalgia (72.55%) and edema (54.12%). Laboratory investigations included mainly elevated eosinophil and leucocyte values. In 52.02% of the patients, the hospitalization period ranged between 8 and 14 days. Most of the patients were from urban areas, but often the source of infection was found in rural areas. Hospitalization of the affected patients required considerable health care resources. The decreasing incidence of trichinellosis in Romania over the last decade has been due to sanitary education programmes for both swine breeders and consumers.  相似文献   

11.
Trichinoscopic examination, pepsin-hydrogen chloride digestion and the ELISA assay were used in an epidemiological survey for the presence of Trichinella spiralis in slaughterhouse pigs over a period of 12 months. The first two methods failed to detect any cases of trichinellosis in sows aged between two to three years. The ELISA assay, however, detected a 2.5% prevalence amongst the 2046 blood specimens tested. Foci of T. spiralis are localized in certain regions only. The discrepancy between the results obtained is likely to be due to the low infection density, undetectable by conventional methods. It is postulated that pigs which are not confined indoors came in contact with the sylvatic strain of Trichinella which is known for low muscle invasiveness.  相似文献   

12.
Evidence of the status of trichinellosis in Canada's national swine herd is provided from data acquired through national surveillance programs and from a prevalence study of Trichinella in wild boar and domestic swine. More than 500,000 swine tested at abattoirs in ongoing animal health surveys since 1980 and 2 national swine serological surveys (1985 and 1990) showed no evidence of Trichinella infection, except for 3 occurrences in a small infected zone in Nova Scotia. The prevalence study of domestic swine and wild boar was conducted for the prevalence of Trichinella after an epidemiological investigation of a 1993 outbreak of human trichinellosis in Ontario showed that the disease was linked to the consumption of wild boar meat originating from 2 farms in the province. Sera and tissues were collected from 391 wild boar and 216 domestic swine originating from 228 farms in Quebec, Ontario, Manitoba and Saskatchewan. The survey examined approximately 37% of the wild boar slaughtered in Canada in 1994. A pepsin-HCl digestion test of the tissues and an ELISA performed on the sera did not yield any positive results. These findings and the lack of human cases of Trichinella from the consumption of Canadian pork for nearly 2 decades suggest that the parasite has been rare in domestic swine and wild boar raised in Canada. Trichinella spiralis has only been found sporadically in swine in a small region within Nova Scotia.  相似文献   

13.
Trichinellosis is a food-borne, zoonotic disease caused by a parasitic organism. Pork containing muscle larvae represents the most important source of human trichinellosis. In Germany, each slaughtered domestic swine is systematically sampled and examined for Trichinella spp. European Union legislation (EC (No.) 2075/2005) condones the approach of a risk-oriented meat inspection for Trichinella in pigs which is accompanied by monitoring programmes for pig holdings and reservoir animals. Here we discuss the current epidemiological situation of Trichinella in the sylvatic cycle in Germany and the implications for the implementation of risk-based sampling.  相似文献   

14.
The identification of Trichinella infection in pigs in Croatia has traditionally been done by inspection of individual carcasses. In response to outbreaks of human trichinellosis in the last decade, the Croatian Ministry of Agriculture and Forestry instituted compulsory trichinelloscopic examination of tissue from both commercially and privately slaughtered swine. The purpose of this study was to compare trichinelloscopy and artificial digestion for use in samples containing low numbers of larvae. Each assay was used to test 1,769 field positive samples, 290 of which contained 6 or less larvae per gram of muscle tissue. The sensitivity and specificity of trichinelloscopy with 6 or less l pg was 43.4 and 88%, respectively. kappa-Value as a measure of agreement between trichinelloscopy and artificial digestion was 0.27%. It is noteworthy that a considerable number of the 103 (52%) negative animals on trichinelloscopy contained>or=6l pg which is enough to cause clinical trichinellosis. These findings support other studies that indicate trichinelloscopy is not a method of choice and that it is necessary to implement more sensitive procedures such as artificial digestion.  相似文献   

15.
Trichinellosis: a worldwide zoonosis   总被引:39,自引:0,他引:39  
Trichinella spp. are some of the most widespread parasites infecting people and other mammals all over the world, regardless of climate. This paper attempts to describe the present status of trichinellosis worldwide and to determine if and why trichinellosis is emerging or re-emerging. The global prevalence of the disease is difficult to evaluate but as many as 11 million people may be infected. More than 10000 cases of human trichinellosis were reported by the International Commission on Trichinellosis from 1995 to June 1997 and about 10000 porcine infections were reported by the Office International des Epizooties in 1998. The disease is particularly worrisome in the Balkans, Russia, the Baltic republics, in some parts of China and Argentina. Horsemeat-related outbreaks have been reported in France and Italy and have involved about 3000 patients in the past 25 years. The emergence of trichinellosis in some countries is explained by a better knowledge of the disease (formerly often misdiagnosed as influenza), modifications of consumer habits, re-forestation in Europe and increase of wild game, importation of meats from countries where trichinellosis is endemic and failure of veterinary control due to human error or to social upheavals. This disease linked to meat-consumption which is theoretically easy to prevent by adequate cooking, freezing and veterinary controls, should deserve the attention of all persons involved in public health and it could be eradicated at least from domestic pigs.  相似文献   

16.
Epidemiology of trichinellosis in Asia and the Pacific Rim   总被引:4,自引:0,他引:4  
The epidemiology of trichinellosis, species of Trichinella present and the food and eating habits of people affected in Asia and the Pacific Rim are reviewed with emphasis on Japan, China and Thailand. Trichinella seems to be prevalent throughout this region although outbreaks of trichinellosis have not been reported in some areas. Major outbreaks of the disease have been reported primarily in China and Thailand. This is the result of three factors: (1) China and Thailand are highly endemic areas for this parasite; (2) the two countries are well-organized and there is a public health system that enables precise reporting of disease outbreaks and (3) culinary habits provide many opportunities to eat undercooked meats. Trichinella found in Asia and the Pacific Rim includes both encapsulated species (Trichinella spiralis, Trichinella britovi, Trichinella nativa) and noncapsulated species (Trichinella pseudospiralis, Trichinella papuae). T. britovi, isolated in Japan, is a different genotype from the European strain. Therefore, the Japanese strain of T. britovi is designated Trichinella T9. Human trichinellosis caused by T. pseudospiralis has occurred in New Zealand and Thailand. Tasmania has had animal cases of T. pseudospiralis infection and animals with T. papuae infection have been found in Papua New Guinea. Economic losses due to Trichinella infection are not negligible in China, where there have been more than 500 outbreaks of human trichinellosis, affecting more than 20,000 people and causing more than 200 deaths. In Thailand, over the past 27 years, 120 outbreaks were reported involving nearly 6700 patients and 97 deaths. Japan has had fewer outbreaks and some sporadic cases have been attributed to imported infection.  相似文献   

17.
The Inuit population of the Arctic has always been at risk of acquiring trichinellosis and severe outbreaks have been recorded in Alaska and Canada. In West Greenland, a number of large outbreaks took place during the 1940s and 1950s; they involved total 420 cases including 37 deaths. Since then only sporadic cases have been reported. Here, we describe an outbreak of infection with Trichinella spp. after consumption of infected meat presumably from walrus or polar bear caught in western Greenland. Six persons who had eaten of the walrus and polar bear meat were two males and four females, age range 6--47 years. Using ELISA and Western blot analysis (Trichinella-specific IgG antibodies against excreted/secreted antigen and synthetic tyvelose antigen, respectively) four of these persons were found to be sero-positive for Trichinella antibodies, with three of these having clinical symptoms compatible with trichinellosis. On re-test, 12--14 months later one of the two sero-negative persons had sero-converted, probably due to a new, unrelated infection. This study demonstrates that acquiring Trichinella from the consumption of marine mammals remains a possibility in Greenland, and that cases may go undetected. Trichinellosis in Greenland can be prevented by the implementation of public health measures.  相似文献   

18.
Serological evidence of Trichinellosis in local pigs of Nepal   总被引:1,自引:0,他引:1  
In Nepal, animal husbandry is a major source of income. Pig husbandry is practiced in rural, peri-urban, and urban communities. Free ranging "back yard" pigs and the practice of feeding offal is a very common management practice which potentially allows for the transmission of trichinellosis; however, this zoonosis has never been reported from this region. A total of 425 serum samples were collected from local pigs. These were initially screened by ELISA after which positive samples were examined by Western blot. This procedure identified two samples which had clear specific bands for Trichinella; however, muscle samples tested by HCL-pepsin digestion were found to be negative. If these highly specific serological analyses are confirmed, this would be the first report of trichinellosis in Nepal and a prevention program should be initiated to limit the access of pigs to open garbage dumps which exist both in towns and on farms.  相似文献   

19.
Over the years, the opinions of clinicians on the existence of the so-called chronic trichinellosis or late sequelae of infection have differed. However, the persistence of a humoral immune response against Trichinella in these late-stage patients has been confirmed using specific tests such as the competitive inhibition assay (CIA). We evaluated sera from late-stage trichinellosis patients (2--8 years from acute infection), for their reactivity against Trichinella spiralis antigens. The following tests were carried out: (i) indirect immunofluorescence assay (IFA), performed on muscle sections from mice, 30 days following synchronous infection by intramuscular injection with T. spiralis newborn larvae (NBL); (ii) enzyme immunoassay, employing a synthetic beta-tyvelose antigen conjugated to bovine serum albumin (BSA-Ag); and (iii) western blot (WB) with both an "in house" kit and a commercial kit. The results of IFA obtained by confocal laser microscopy showed that sera reacted against both surface and internal structures of L(1) larvae but at varying levels. Employing the synthetic antigen, EIA showed that 50% of sera tested were positive for the presence of specific antibodies against beta-tyvelose. By WB, all sera were reactive with the 45 k Da glycoprotein (45 gp). These data suggest that reactivity against the beta-tyvelosylated 45 gp persists even in very late stages of human trichinellosis.  相似文献   

20.
Trichinella sp. infection has been documented in both humans and animals in most Mediterranean countries, yet in the past 60 years no infections have been reported on the Mediterranean islands. We describe the first outbreak of Trichinella sp. infection to have been reported on the island of Sardinia. The outbreak occurred in two villages in 2005 and involved 11 persons who had eaten raw sausages made from the same free-ranging sow. All 11 persons developed signs and symptoms of trichinellosis and seroconverted within 48 days of consuming the infected meat. The etiological agent was Trichinella britovi. Sardinia, like all Mediterranean islands, had been considered to be Trichinella-free. The present report, together with a recent report of T. britovi infection in animals on the nearby island of Corsica (France), raises questions as to the validity of the concept of Trichinella-free areas or regions.  相似文献   

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