Venereal Route Research Articles

Characterization of the cervicovaginal microbiota of female beef cattle harboring Campylobacter fetus subsp. venerealis using 16S rDNA gene sequencing.

Bovine genital campylobacteriosis (BGC) is a leading cause of return to estrus in cows. The etiologic agent, Campylobacter fetus subsp. venerealis (Cfv) is transmitted by venereal route. Hence, the surrounding reproductive tract microenvironment could play a role in return to estrus in cows. The presence of Cfv in cervicovaginal mucus of Angus breed females provide three experimental groups, which were subject to bacteriome analyses: 10 Cfv-positive cows (CVP), 10 Cfv-negative cows (CVN), and 10 nonsexually active heifers (NSA). Cows with return to estrus showed higher bacterial richness than NSA. Beta diversity analysis showed a significant difference (P = 0.006) in bacterial composition among the three groups analyzed (CVP, CVN, and NSA). However, no significant difference was found when comparing the CVP versus CVN groups. Ureaplasma and Pseudomonas were the genera most frequently observed in NSA, being Ureaplasma the predictor genus to that group, whereas Alistipes, Bacteroides, Rikenellaceae_RC9_gut_group, UCG-005, and UCG-10 were both significantly more abundant and predictors genera in cows with return to estrus. Our results provide an overview of the cervicovaginal bacterial microbiota in cows harboring Cfv and improve the knowledge of the pathogenesis of BGC.

Molecular detection of vector-borne pathogens in semen from dogs in southeastern Brazil.

Vector-borne pathogens (VBPs) are primarily transmitted by arthropod vectors, but secondary ways of transmission have been described, including via venereal route. Nonetheless, there is still limited research on possible sexual transmission of VBPs in dogs. We molecularly investigated the presence of vector-borne pathogens in semen from dogs living in an area where these agents are endemic. Upon PCR testing, seven out of 22 (31.8%) semen samples tested positive for at least one VBP, whereas simultaneous positivity to two or more pathogens was detected in three (13.6%) dogs. Among pathogens detected in semen, Trypanosoma cruzi (n=1) and Leishmania infantum (n=3) were identified to species level by restriction fragment length polymorphism analysis. Attempts to sequence PCR products from other pathogens were unsuccessful, but coupled epidemiological and molecular data suggest the presence of Anaplasma platys (n=5), Babesia vogeli (n=1) and Ehrlichia canis (n=1) in semen from dogs. Further experimental studies would be needed to confirm the sexual transmission hypothesis for these VBPs and also the possible implications of these findings for canine reproduction.

Plant-Mediated Horizontal Transmission of Asaia Between White-Backed Planthoppers, Sogatella furcifera.

Asaia is a bacterial symbiont of sugar-feeding insects that has been shown to be vertically transmitted by maternal transmission and paternal transmission mechanism, and to be horizontally transmitted via co-feeding artificial diet and venereal routes. Here, the first case of plant-mediated horizontal transmission of Asaia between white-backed planthoppers (WBPH), Sogatella furcifera, was reported. In Asaia-infected WBPH, Asaia was detected mostly in salivary glands and to a less extent in stylets. The rice leaf sheaths fed by Asaia-infected WBPH for 12 h were all positive with Asaia, where Asaia persisted for at least 30 d but was localized in the feeding sites only. When confined to Asaia-infected leaf sheaths for 7 d at the sites pre-infested by the Asaia-infected WBPH, all Asaia-free WBPH became infected with Asaia and the acquired Asaia could be vertically transmitted to their offspring. Phylogenetic analysis confirmed an identical Asaia strain in the Asaia-infected donor WBPH, the Asaia-infected leaf sheaths, and the newly infected recipient WBPH. Our findings provide direct evidence for the first time that rice plant can mediate horizontal transmission of Asaia between WBPH, which may contribute to the spread of Asaia in the field WBPH populations.

Update on Trichomoniasis

In recent years diagnostic surveillance for bovine trichomoniasis has increased since most states require testing prior to interstate movement of non-virgin bulls. However, bovine trichomoniasis continues to be an economically significant disease, particularly in beef cattle, in much of the United States. The disease produces no clinical signs in bulls but can have devastating reproductive consequences on females resulting in reduced calf crops and extended calving seasons. The organism is efficiently transmitted via the venereal route. Although prevalence may be highest in older bulls it has been documented to occur in non-virgin bulls of any age. Bulls are believed to be persistently infected but females develop short lived immunity and naturally clear the infection within 3-22 months. Diagnosis is made by culture in selective media and/or by PCR identification of the organism in smegma samples collected by preputial scraping. Samples of reproductive or fetal fluids obtained from females can also be tested. Readers should consult their state veterinary diagnostic labs for instructions on sample preparation and shipment.
 Control of trichomoniasis is primarily through testing and culling of positive bulls. There are no approved, effective treatments available. However, vaccination of females will, in most cases, improve reproductive indices in infected herds.

Preliminary investigation on feline coronavirus presence in the reproductive tract of the tom cat as a potential route of viral transmission.

ObjectivesFeline infectious peritonitis (FIP) is an immune-mediated disease initiated by feline coronavirus (FCoV) infection. To date, the only proven route of transmission is the faecal–oral route, but a possible localisation of FCoV in the reproductive tract of tom cats is of concern, owing to the involvement of the male reproductive tract during FIP and to the presence of reproduction disorders in FCoV-endemic feline catteries. The aim of the study was to investigate the presence and localisation of FCoV in semen and/or in the reproductive tract of tom cats, and its possible association with seroconversion and viraemic phase.MethodsBlood, serum, semen and/or testicle samples were obtained from 46 tom cats. Serology was performed on 38 serum samples, nested reverse transcriptase PCR (nRT-PCR) and reverse transcriptase quantitative PCR (RT-qPCR) were performed on 39 blood samples and on 17 semen samples, and histology, immunohistochemistry and nRT-PCR were performed on 39 testicles.ResultsTwenty-four of 38 serum samples were positive on serology. Semen samples were negative on RT-PCR and RT-qPCR for FCoV, while all blood samples were negative at both molecular methods, except for one sample positive at RT-qPCR with a very low viral load. All testicles were negative at immunohistochemistry, while six were positive at nRT-PCR for FCoV. Serology and blood PCR results suggest that the virus was present in the environment, stimulating transient seroconversion. FCoV seems not to localise in the semen of tom cats, making the venereal route as a way of transmission unlikely. Although viral RNA was found in some testicles, it could not be correlated with the viraemic phase.Conclusions and relevanceIn the light of these preliminary results, artificial insemination appears safer than natural mating as it eliminates the direct contact between animals, thus diminishing the probability of faecal–oral FCoV transmission.

Evidence of porcine epidemic diarrhea virus (PEDV) shedding in semen from infected specific pathogen-free boars

In 2013, PED emerged for the first time in the United States (US). The porcine epidemic diarrhea virus (PEDV) spread quickly throughout North America. Infection with PEDV causes watery diarrhea and up to 100% mortality in piglets, particularly for highly pathogenic non-InDel strains circulating in the US. PEDV is mainly transmitted by the fecal–oral route. Transmission via the venereal route has been suspected but not previously investigated. The aim of the study was to determine if PEDV could be detected in semen from infected specific pathogen-free (SPF) boars inoculated with a PEDV US non-InDel strain suggesting venereal transmission may occur. Two boars orally inoculated with PEDV showed clinical signs and virus shedding in feces. Transient presence of the PEDV genome was detected by RT-qPCR in the seminal (5.06 × 102 to 2.44 × 103 genomic copies/mL) and sperm-rich fraction of semen (5.64 × 102 to 3.40 × 104 genomic copies/mL) and a longer duration of viral shedding was observed in the sperm-rich fraction. The evidence of PEDV shedding in semen raises new questions in term of disease spread within the pig population with the use of potentially contaminated semen.

Changing clinical scenario in Chandipura virus infection

Chandipura virus (CHPV) (Vesiculovirus: Rhabdoviridae) garnered global attention as an emerging neurotropic pathogen inflicting high mortality in children within 24 h of commencement of symptoms. The 2003-2004 outbreaks in Central India witnessed case fatality rates ranging from 56-75 per cent in Andhra Pradesh and Gujarat with typical encephalitic symptoms. Due to the acute sickness and rapid deterioration, the precise mechanism of action of the virus is still unknown. Recent studies have shown increased expression of CHPV phosphoprotein upto 6 h post infection (PI) demonstrating CHPV replication in neuronal cells and the rapid destruction of the cells by apoptosis shed light on the probable mechanism of rapid death in children.Phlebotomine sandflies are implicated as vectors due to their predominance in endemic areas, repeated virus isolations and their ability to transmit the virus by transovarial and venereal routes. Significant contributions have been made in the development of diagnostics and prophylactics, vaccines and antivirals. Two candidate vaccines, viz. a recombinant vaccine and a killed vaccine and siRNAs targeting P and M proteins have been developed and are awaiting clinical trials. Rhabdomyosarcoma and Phlebotomus papatasi cell lines as well as embryonated chicken eggs have been found useful in virus isolation and propagation. Despite these advancements, CHPV has been a major concern in Central India and warrants immediate attention from virologists, neurologists, paediatricians and the government for containing the virus.

Abortogenic viruses in horses

SummaryViral causes of abortion include equine viral arteritis (EVA) and infection with equine herpesviruses‐1 and ‐4 (EHV‐1 and EHV‐4). Transmission of equine arteritis virus (EAV) occurs through respiratory, venereal or transplacental routes. Horizontal respiratory transmission of EAV results from exposure to infective nasopharyngeal secretions from acutely infected horses. For this transmission to occur, direct and close contact between horses is necessary. Venereal infection is an efficient method of transmission, with seroconversion of 85 to 100% of seronegative mares bred to virus shedding stallions. Asymptomatic carrier stallions are the essential natural reservoir of equine arteritis virus. Equine herpesviruses‐1 and ‐4 infect a susceptible host, replicate and establish a lifelong latent infection without any associated clinical signs. Reactivation of latent infections can result from factors such as stress and intercurrent disease. The control of these diseases is by implementation of appropriate management and hygiene measures, supplemented by vaccination and, in the case of EVA, by the identification of persistently infected stallions, which can be removed from breeding or continue to be bred to if managed under controlled conditions to prevent the risk of an outbreak of the disease.

Transmission, Host Specificity, and Seasonal Occurrence ofCyrtosomum penneri(Nematoda: Atractidae) in Lizards from Florida

Experimental infections and field-collected lizards were used to investigate issues of transmission, host specificity, and seasonal occurrence in the nematode Cyrtosomum penneri (Cosmocercoidea: Atractidae). Anolis sagrei (87 males, 42 females) were captured from the Florida Southern College campus, Polk County, Florida, from October 2010 to September 2011, and 8,803 C. penneri were collected from their intestines. During the breeding season all sexually mature (SVL ≥ 34 mm) A. sagrei were infected, whereas juvenile lizards (SVL <34 mm) were never infected. Experimental infections, using A. sagrei , found that worms were transferred to new hosts venereally, but not during oral exposures. Mating trials confirmed that worms were consistently transferred between hosts during copulation under natural conditions. Experimental exposures found that land snails and crickets do not serve as transport or intermediate hosts, which supports the idea that C. penneri is transferred only during host copulation. Experimental infections to test host specificity in C. penneri successfully infected A. sagrei , Hemidactylus turcicus , and Sceloporus undulatus , but not Anolis carolinensis or Plestiodon inexpectatus. Overall, this is the first study to fully elucidate the life cycle of any atractid nematode, and we suggest a venereal route of transmission for all atractid worms that infect reptilian hosts. Our findings also have implications for the host's reproductive and behavioral biology, e.g., support for covert or satellite males in the A. sagrei mating system.

Detection of Leishmania parasites in the testis of a dog affected by orchitis: case report

BackgroundTransmission of canine leishmaniasis (CanL), a severe infection caused by L. infantum, usually occurs through the sand fly bite to the vertebrate host. A venereal route of transmission has also been suggested, but this issue is still controversial.FindingsHere, we report a case of a dog affected by orchitis showing a clinical profile of L. infantum infection. By exploiting a real-time PCR assay, we detected a significantly higher DNA load of the parasite in the lymph node and testis than in blood and urine samples collected from the dog.ConclusionsOur results suggest that: 1) L. infantum infection can be associated with testicular lesions in naturally infected dogs; 2) genital involvement could result in shedding of the parasites in the semen, favoring venereal transmission of the disease.

Transmission of the caprine arthritis–encephalitis virus through artificial insemination

The objective of present study was to evaluate the transmissibility of the caprine arthritis–encephalitis virus (CAEV) through artificial insemination (AI), and to assess the influence of viral load on this probable transmission. It also aims to verify whether the inflammatory process caused by the use of intravaginal sponges would facilitate virus entry in the female reproductive tract. For this purpose, 30 undefined breed goats were used, all serologically negative for CAEV. One Anglo-Nubian buck, also seronegative, was used to artificially inseminate females in this study. His semen was contaminated with the standard CAEV-Cork virus strain, with two distinct infective titres, one 106TCID50/mL, for high viral load (HVL), and another of 102TCID50/mL, for low viral load (LVL). Females had estrus synchronised by using two protocols, intravaginal sponges in Group 1 (G1, N=15) and auricular subcutaneous implants in Group 2 (G2, N=15). For inseminations, the goats were divided into three groups of 10 animals each. One group was inseminated with HVL, another with LVL and the third with semen from the same virus-free buck, as a negative control. The experiment was conducted in accordance to the ethical principles for animal experimentation. Statistical analyses were performed by the chi-square test (P<0.05). Thirty days after insemination, the experimental infection was confirmed, when 12 out of the 20 (60%) inseminated goats had seroconverted. Sixty days after insemination, all females from the HVL and LVL groups presented anti-CAEV antibodies. There was no statistical difference (P>0.05) among groups regarding viral loads nor between the two estrus synchronisation protocols. Goats from the control group remained seronegative throughout the experiment (12months). Concerning reproductive parameters, no difference was found between the control group and the infected groups. Based on these results, it is possible to conclude that the virus can be transmitted through artificial insemination with infected semen. Therefore, the venereal route is a potential route of infection.

Horizontal transmission of the symbiotic bacterium Asaia sp. in the leafhopper Scaphoideus titanus Ball (Hemiptera: Cicadellidae)

BackgroundBacteria of the genus Asaia have been recently recognized as secondary symbionts of different sugar-feeding insects, including the leafhopper Scaphoideus titanus, vector of Flavescence dorée phytoplasmas. Asaia has been shown to be localized in S. titanus gut, salivary glands and gonoducts and to be maternally transmitted to the progeny by an egg smearing mechanism. It is currently not known whether Asaia in S. titanus is transmitted by additional routes. We performed a study to evaluate if Asaia infection is capable of horizontal transmission via co-feeding and venereal routes.ResultsA Gfp-tagged strain of Asaia was provided to S. titanus individuals to trace the transmission pathways of the symbiotic bacterium. Co-feeding trials showed a regular transfer of bacterial cells from donors to recipients, with a peak of frequency after 72 hours of exposure, and with concentrations of the administrated strain growing over time. Venereal transmission experiments were first carried out using infected males paired with uninfected females. In this case, female individuals acquired Gfp-labelled Asaia, with highest infection rates 72-96 hours after mating and with increasing abundance of the tagged symbiont over time. When crosses between infected females and uninfected males were conducted, the occurrence of “female to male” transmission was observed, even though the transfer occurred unevenly.ConclusionsThe data presented demonstrate that the acetic acid bacterial symbiont Asaia is horizontally transmitted among S. titanus individuals both by co-feeding and venereal transmission, providing one of the few direct demonstrations of such a symbiotic transfer in Hemiptera. This study contributes to the understanding of the bacterial ecology in the insect host, and indicates that Asaia evolved multiple pathways for the colonization of S. titanus body.

Promiscuous mating in feral pigs (Sus scrofa) from Texas, USA

Context Feral pigs represent a significant threat to agriculture and ecosystems and are disease reservoirs for pathogens affecting humans, livestock and other wildlife. Information on the behavioural ecology of feral pigs might increase the efficiency and effectiveness of management strategies. Aims We assessed the frequency of promiscuous mating in relation to oestrous synchrony in feral pigs from southern Texas, USA, an agroecosystem with a widespread and well established population of feral pigs. An association between multiple paternity of single litters and synchrony of oestrous may indicate alternative mating strategies, such as mate-guarding. Methods We collected gravid sows at nine sites in southern Texas during 2005–07. We used a panel of DNA microsatellite markers to estimate frequency of multiple paternity and the distribution of male mating among litters of feral pigs. Conception dates were determined by fitting average fetal crown–rump measurements within litters to expected fetal development relative to gestation time. Key results We found evidence of multiple paternity in 21 of 64 litters (33%) from seven of nine sites sampled. Synchrony of oestrous did not influence promiscuous mating, as we found multiple paternity at sites with synchronous and asynchronous oestrous. Males sired from 8 to 11 offspring at three sites where &gt;10 litters were sampled. Mean litter size (5.4) was less than the best-fit value for the number of offspring, indicating that some males sired offspring with ≥ 2 females. Key conclusions Feral pigs in Texas appear to be promiscuous under a range of demographic conditions, unlike wild boar and feral pigs in other regions. The ecological and behavioural factors affecting multiple paternity are not clear, but may include male–male competition, harassment avoidance, genetic benefits for offspring, response to macro-habitat conditions, or selection. Implications A high incidence of sexual contact among individuals may increase the opportunity for diseases transmitted by oral or venereal routes, such as swine brucellosis and pseudorabies. In addition, fertility-control methods targeting males only are likely to be inefficient if female promiscuity is high; methods targeting females or both sexes jointly may be more effective.

Porcine brucellosis (Brucella suis)

Porcine brucellosis (Brucella suis)

Detection of Neospora caninum in semen of bulls

In cattle, transplacental infection is the main route of Neospora caninum transmission, but postnatal transmission by the oral uptake of sporozoite-containing oocysts shed by dogs may also be possible. Other routes of horizontal transmission, such as the venereal route, have not been investigated. In this study, we evaluated the presence of N. caninum DNA by a nested-PCR in fresh non-extended semen and frozen extended semen straws of five Holstein–Friesian bulls with naturally-acquired neosporosis. The infection status was assessed by an immunofluorescent antibody test (IFAT) and confirmed by immunoblotting (IB). Because of inhibitory components of semen, a protocol was developed to purify N. caninum DNA from bovine semen. Sporadically, N. caninum DNA was detected in non-extended fresh semen samples and frozen extended semen straws of the five seropositive bulls. In all positive samples, specific DNA was consistently found in the cell fraction of semen and not in seminal plasma. The parasite mean load in positive fresh semen samples determined by a real-time PCR was low oscillating between 1 and 2.8 parasites/ml of semen (maximum parasite load detected in one sample was 7.5 parasites/ml of semen). In parallel, another three similar but uninfected bulls acted as controls and no N. caninum DNA was amplified in any of their fresh and straw semen samples assayed. Whether venereal transmission plays a role in the spread of bovine neosporosis needs to be determined.

Venereal transmission of pseudorabies viruses indigenous to feral swine.

Between 1995 and 1998, we designed a series of studies in which we attempted to determine the main routes of transmission involved in the natural infection of pseudorabies virus (PRV) indigenous to free-ranging feral swine (Sus scrofa). Naturally infected feral sows transmitted the infection to uninfected feral boars, with which they had been commingled for a 6-wk period. Pseudorabies virus was isolated from boar preputial swabs, but not from nasal swabs. Three of the same PRV-infected feral sows did not transmit the infection to domestic boars during a 16 wk commingling period, despite the fact that they became pregnant. Feral boars, naturally infected with PRV transmitted the virus to domestic gilts while penned together during 6 wk. Pseudorabies virus was isolated from vaginal swabs, but not from nasal swabs of gilts, after 2 and 3 wk of commingling. When the same infected boars were commingled with either feral or domestic boars for 13 wk, PRV transmission did not occur. None of the exposed boars developed neutralizing antibodies or yielded virus from their preputial or nasal swabs. Our results indicate that PRV indigenous to feral swine is preferentially transmitted to feral or domestic swine of the opposite sex by the venereal route. This mode of transmission differs from that seen in the natural transmission of PRV prevalent in domestic swine, where contaminated secretions, excretions and aerosols are responsible for the spread of the virus. Based on these results, we feel that as long as feral swine do not come into direct contact with domestic swine, PRV-infected feral swine probably pose only a limited risk to the success of the National Pseudorabies Eradication Program. The fact that PRV is usually transmitted from feral to domestic swine at the time of mating would indicate that the isolation of domestic herds by the use of a "double fence," should be adequate protection against reinfection with PRV.

Equine viral arteritis

Equine viral arteritis is reviewed with specific reference to clinical features, etiology, transmission, diagnosis, epidemiology, and current methods for the control of this disease. There is evidence of variation in pathogenicity among strains of equine arteritis virus. Virus transmission occurs primarily by the respiratory and venereal routes during the acute phase of the infection. The long-term carrier stallion appears to play a major epidemiological role in dissemination and perpetuation of the virus. Unlike the stallion, the carrier state has yet to be demonstrated in the mare or foal. A commercial modifiedlive equine arteritis virus vaccine has been shown to be safe and efficacious for stallions and mares. The disease can be controlled by identification and isolation of carrier stallions, immunization of seronegative stallions, and by restricting the breeding of equine arteritis virus-shedding stallions to equine arteritis virus vaccinated or seropositive mares.

The dangers of disease transmission by artificial insemination and embryo transfer

This review summarizes the major infectious diseases of the three major agricultural species (cattle, sheep and pigs) and horses, and presents the evidence for and against the possibility of infectious agents being transmitted between animals via the venereal route or by the use of semen or early embryos in commercial artificial insemination (AI) or embryo transfer (ET). Cattle feature most prominently in the widespread distribution of frozen semen, and national and international organizations have set out guidelines to work towards disease-free bull studs with semen free from potential pathogens. With the control of major epizootic diseases, attention has been focused on such diseases as IBR, BVD and blue tongue, where clinical signs are rarely evident but the detection of virus in semen is of great importance. New information on the relevance of bacterial disease such as Mycobacterium paratuberculosis, campylobacteriosis and leptospirosis is reviewed, along with details of the mycoplasma and ureaplasma species of the bull's genital tract. Bovine spongiform encephalopathy (BSE) has attracted much research and semen is not regarded as a source of infection. New work on the pathogenesis of a number of diseases and the use of new biotechnology in diagnosis is included. The International Embryo Transfer Society (IETS) has encouraged a great deal of experimental work--much originating in Canada--on the risk of transmission of disease from donors to recipients via a 7-day-old blastocyst. There has been much success in demonstrating that with an approved protocol of handling the embryos, to date there is very little danger in disease transmission with both viruses and bacteria. The mycoplasma group appear more intractable and the role of BSE is still being evaluated. In sheep, scrapie, Brucella ovis infection and blue tongue feature in current work. In the pig there is a surge in international movement of pig semen, and Aujeszky's disease and the new so-called Blue Ear disease feature prominently. Much work is in progress on infectious agents likely to be found in the semen of stallions, with an expanding trade in the international movement of chilled and frozen semen. Equine embryo transfer experiments are hampered by the very limited number of embryos available. Reference is also made to the further risk of disease transmission by in vitro manipulated embryos.

Venereal Transmission of St. Louis Encephalitis Virus by Culex quinquefasciatus Males (Diptera: Culicidae)

Uninfected, virgin, colonized Culex quinquefasciatus Say females became infected when caged with males that had been infected with St. Louis encephalitis (SLE) virus by inoculation. When these females were assayed 7 or 28 d after first exposure to infected males, 23% and 25%, respectively, were infected with SLE virus. Fifty-eight percent (n = 83) of the inseminated females were infected with SLE virus, whereas only 23% (n = 23) of virgin females were infected. These data show that at least some of the horizontal transmission demonstrated was by a venereal route. This study indicates that if Cx. quinquefasciatus males were infected vertically with SLE virus in nature, they could infect their female mates horizontally.

Contagious equine metritis—epidemiology and control

Summary Since 1977, when contagious equine metritis (CEM) was first described and etiologically defined as a previously unrecognized venereal disease of the horse, the disease has been reported from countries in Europe, Asia, Australia, North and South America. The potential for spread of CEM through the international movement of horses was realized early, with the introduction of the disease into some countries following the importation of a carrier animal. The carrier state has been confirmed in both the mare and the stallion, with such animals providing a focus for initiating fresh outbreaks of the disease by dissemination of the causal organism primarily by the venereal route. Successful control of CEM within an equine population requires the identification and treatment of culture-positive mares and stallions. Although such a control program is based primarily on the bacteriologic screening of both stallion and mare populations to detect clinical and carrier animals, it also necessitates the prompt diagnosis of CEM and implementation of the requisite standards of stud management hygiene if spread of the disease is to be prevented. Removal of the clitoral sinuses and topical antimicrobial treatment of the clitoral area have been additional control measures required of certain mares imported into the United States from countries in which CEM has been reported. The number of outbreaks of the disease has been greatly reduced if not eliminated in those countries in which a code of practice for the control of CEM has been in force for several years.