Serotype diversity and antimicrobial susceptibility profiles of Actinobacillus pleuropneumoniae isolated in Italian pig farms from 2015 to 2022.

Actinobacillus pleuropneumoniae (APP) is a bacterium frequently associated with porcine pleuropneumonia. The acute form of the disease is highly contagious and often fatal, resulting in significant economic losses for pig farmers. Serotype diversity and antimicrobial resistance (AMR) of APP strains circulating in north Italian farms from 2015 to 2022 were evaluated retrospectively to investigate APP epidemiology in the area. A total of 572 strains isolated from outbreaks occurring in 337 different swine farms were analysed. The majority of isolates belonged to serotypes 9/11 (39.2%) and 2 (28.1%) and serotype diversity increased during the study period, up to nine different serotypes isolated in 2022. The most common resistances were against tetracycline (53% of isolates) and ampicillin (33%), followed by enrofloxacin, florfenicol and trimethoprim/sulfamethoxazole (23% each). Multidrug resistance (MDR) was common, with a third of isolates showing resistance to more than three antimicrobial classes. Resistance to the different classes and MDR varied significantly depending on the serotype. In particular, the widespread serotype 9/11 was strongly associated with florfenicol and enrofloxacin resistance and showed the highest proportion of MDR isolates. Serotype 5, although less common, showed instead a concerning proportion of trimethoprim/sulfamethoxazole resistance. Our results highlight how the typing of circulating serotypes and the analysis of their antimicrobial susceptibility profile are crucial to effectively manage APP infection and improve antimicrobial stewardship.

Community-acquired pleuropneumonia in children: Bacteriological and therapeutic challenges.

Background Community-acquired pleuropneumonia (CPP) is a common complication of pneumonia in children. It is serious given its high morbidity and significant mortality. Aim To study clinical and paraclinical features of CPP in children and to establish a common therapeutic strategy. Methods Our retrospective study included patients who were hospitalized for CPP between 2004 and 2012. All data were collected from patients' medical files. Statistical analysis was made by Epi-Info 6. Results One hundred and sixty four patients were registered. The mean age was 32 months (15 days - 14.5 years). The hospital incidence of CPP doubled between 2004 and 2012. The symptomatology was dominated by fever (93.9%), cough (56.7%) and dyspnea (48.1%). The pleural effusion was frequently moderately abundant and loculated. Pleural sample, performed in 53.6% of cases, was the most beneficial bacteriological examination (p=10-6 ). The bacteriological confirmation was attained in 44.5% of cases with the predominance of Staphylococcus aureus (59%) followed by Streptococcus pneumoniae (26%). The S. aureus occurred basically in most young infants (p=0.04) and was responsible for the most severe cases (p=0.01). The CPP management included heterogeneous intravenous antibiotics associated with a pleural drainage in 40% of cases. The quarter of our patients were transferred to an intensive care unit. Six patients died. Conclusion The bacteriological confirmation is difficult. Pleural aspiration is the key tool. S. aureus is the first microorganism followed by S. pneumoniae. A therapeutic strategy is proposed based on large spectrum intravenous antibiotics. The pleural drainage indication is limited.

Abattoir surveillance demonstrates contagious bovine pleuropneumonia is widespread in Tanzania.

A study was conducted to investigate the presence of contagious bovine pleuropneumonia (CBPP) in the slaughter facilities in 10 regions of Tanzania that reported pathological lesions suggestive of CBPP during meat inspection. The aim was to ascertain if slaughter facilities can be used to monitor the occurrence and spread of CBPP in the country. The study involved a questionnaire survey, clinical examination of animals for CBPP symptoms prior to slaughter and postmortem examination of the respiratory system in slaughtered cattle. A total of 12 slaughterhouses and 31 animal markets were involved in the study. A total of 2736 cattle were slaughtered comprising 1978 and 758 in slaughterhouses and animal markets, respectively. Of the total slaughtered stock, 351 of 2736 (12.8 %) had lesions suggestive of CBPP and of these, 236 (8.6 %) were from slaughterhouses and 115 (4.2 %) from animal markets. Acute CBPP cases were observed in 192 of the 236 (81.4 %) and 71 of the 115 (61.7 %) of the animals inspected in the slaughterhouses and markets, respectively. Chronic cases were encountered in 24 (10.2 %) of the animals slaughtered in the slaughterhouses and 19 (16.5 %) at animal markets. This work has confirmed that targeted monitoring for CBPP lesions through meat inspection can be a useful tool for CBPP surveillance in endemic countries like Tanzania.

An international collaborative study to determine the prevalence of contagious caprine pleuropneumonia by monoclonal antibody-based cELISA.

BACKGROUND: Few serological tests are available for detecting antibodies against Mycoplasma capricolum subsp. capripneumoniae, the causal agent of contagious caprine pleuropneumonia (CCPP). The complement fixation test, the test prescribed for international trade purposes, uses a crude antigen that cross-reacts with all the other mycoplasma species of the "mycoides cluster" frequently infecting goat herds. The lack of a more specific test has been a real obstacle to the evaluation of the prevalence and economic impact of CCPP worldwide. A new competitive ELISA kit for CCPP, based on a previous blocking ELISA, was formatted at CIRAD and used to evaluate the prevalence of CCPP in some regions of Kenya, Ethiopia, Mauritius, Tajikistan and Pakistan in an international collaborative study. RESULTS: The strict specificity of the test was confirmed in CCPP-free goat herds exposed to other mycoplasma species of the "mycoides cluster". Prevalence studies were performed across the enzootic range of the disease in Africa and Asia. Seroprevalence was estimated at 14.6% in the Afar region of Ethiopia, whereas all the herds presented for CCPP vaccination in Kenya tested positive (individual seroprevalence varied from 6 to 90% within each herd). In Mauritius, where CCPP emerged in 2009, nine of 62 herds tested positive. In Central Asia, where the disease was confirmed only recently, no positive animals were detected in the Wakhan District of Afghanistan or across the border in neighboring areas of Tajikistan, whereas seroprevalence varied between 2.7% and 44.2% in the other districts investigated and in northern Pakistan. The test was also used to monitor seroconversion in vaccinated animals. CONCLUSIONS: This newly formatted CCPP cELISA kit has retained the high specificity of the original kit. It can therefore be used to evaluate the prevalence of CCPP in countries or regions without vaccination programs. It could also be used to monitor the efficacy of vaccination campaigns as high-quality vaccines induce high rates of seroconversion.

Characterization of nonencapsulated Actinobacillus pleuropneumoniae serovar K12:O3 isolates.

Three Actinobacillus pleuropneumoniae isolates from clinical cases of porcine pleuropneumonia were positive by capsular serovar 12-specific PCR assay, but not reactive to antiserum prepared against serovar 12 using the rapid slide agglutination (RSA) test. The isolates were positive for apxIICA, apxIIICA, apxIBD, apxIIIBD, and apxIVA in the PCR toxin gene assay, which is the profile seen in serovars 2, 4, 6, 8, and 15, and reacted with antisera against serovars 3, 6, 8, 15, and 17. Nucleotide sequence analysis revealed that genes involved in the biosynthesis of capsular polysaccharide of the 3 isolates were identical or nearly identical to those of serovar 12. However, genes involved in the biosynthesis of O-polysaccharide of the 3 isolates were highly similar to those of reference strains of serovars 3, 6, 8, 15, 17, and 19. In agreement with results from the RSA test, transmission electron microscopic analysis confirmed the absence of detectable capsular material in the 3 isolates. The existence of nonencapsulated A. pleuropneumoniae serovar K12:O3 would hamper precise serodetection.

[Present Situation of Contagious Bovine Pleuropneumonia in Central African Republic]. / Situation Actuelle de la Péripneumonie Contagieuse Bovine en République Centrafricaine.

Aims: The aim of this study was to analyse the current situation of Contagious Bovine Pleuropneumonia (CBPP) in the Central African Republic (CAR) by seroprevalence analysis, as well as isolation and characterization of strains of the etiologic agent, Mycoplasma mycoides mycoides (Mmm), circulating in livestock breeding regions. Material and methods: The strains obtained were subjected to whole genome sequencing by Illumina technology and genotyped using the eMLST technique based on 62 genes of the Mmm core genome. Their sensitivity to tetracycline was assessed by determination of the minimum inhibitory concentration (MIC) on agar. A seroprevalence analysis by competitive ELISA was conducted in livestock breeding regions (West, Centre and East CAR), including both zebu and taurine cattle breeds, and both males and females. Results: The three strains isolated in the three regions of the CAR shared exactly the same genomic sequence. Phylogenetic analysis showed that they were closely related to a strain isolated in the CAR in 1991, also sequenced in this study, and clustered with Mmm strains originating from East and Central Africa. The recent isolates presented increased MIC values, though they were still sensitive to tetracycline. The global CBPP prevalence in the CAR was estimated at 12.5% with no significant differences observed between cattle breeding regions, nor between males and females. However, a significantly higher prevalence was observed in zebu compared to taurine cattle, most likely in relation to their herding system based on cattle transhumance and nomadic pastoralism. Conclusion: CBPP is enzootic in the CAR in spite of control campaigns based on use of the live T1 vaccines, which have shown little efficacy due to poor implementation in the field. New strategies combining controlled use of antibiotics and inactivated vaccines, with increased thermostability, should be well received by livestock keepers and allow a better control of CBPP in the region. The fact that the recent Mmm isolates are still resistant to tetracycles is encouraging.

The first isolation and molecular characterization of Mycoplasma capricolum subsp. capripneumoniae Pakistan strain: A causative agent of contagious caprine pleuropneumonia.

PURPOSE: Mycoplasma capricolum subsp. capripneumoniae (Mccp) causes a severe, usually fatal disease in goats known as Contagious Caprine Pleuropneumonia (CCPP). CCPP is listed by OIE as a notifiable animal diseases, causing economic losses in terms of high morbidity and mortality. Thus far, very limited information is available on the molecular characterization of the unique Mccp strains prevalent in Pakistan. The study was aimed to isolate Mccp local strain for the development of diagnostics and vaccines. METHODS: Samples were collected during November 2017-December 2018 at Northern areas of Pakistan from 10 goat flocks each in Gilgit-Baltistan, Chitral, Swat, Buner, and Hazara. 900 samples were collected; nasal swabs (n = 400), tracheal swabs (n = 150) from naturally infected goats showing clinical signs of CCPP, and lungs tissue (n = 200), pleural fluid (n = 150) from goats at necropsy. RESULTS: The clinical signs recorded were mucopurulent nasal discharges, cough, abdominal respiration and hyperthermia. The post-mortem revealed, pulmonary consolidation, fibrinous pleuropneumonia, and accumulation pleural fluid. The fried egg like growth was observed on agar in 16 (4%), 11 (7.3%), 38 (19%), and 24 (16%) nasal swab, tracheal swabs, lungs and pleural fluid samples, respectively. PCR targeting 16S rRNA gene revealed isolates, belongs to Mycoplasma mycoides cluster, in 72 (8%) samples. Forty one (4.5%) isolates were Mccp by specie specific PCR generating an amplicon of 316 bp. CONCLUSIONS: We successfully isolated local strain of Mccp for the first time in Pakistan. This Mccp strain could be further utilized for the development of diagnostics and control measures against Mccp infection in goats.

Disseminated Mycobacterium kansasii infection in a white-tailed deer and implications for public and livestock health.

We document a case of Mycobacterium kansasii, a rare, zoonotic bacterium, in a white-tailed deer (WTD; Odocoileus virginianus) in East Baton Rouge Parish, Louisiana. Grossly, the deer had fibrinous pleuropneumonia with yellow, mineralized nodules scattered throughout the lungs and extending to the pleura. The kidneys were enlarged and had numerous pale foci in the cortex. Microscopically, the pulmonary architecture was replaced by variably sized, multifocal-to-coalescing granulomas with peripheral histiocytes and fewer multinucleate giant cells, and necrotic centers with mineralization and hemorrhage. The latter rarely contained one to a few acid-fast, slender, 7-µm long bacteria, for which beaded morphology was sometimes evident. Similar acid-fast bacteria were also within histiocytes in the kidney. PCR assay of fresh lung sample and subsequent sequencing revealed a non-tuberculosis mycobacterium, M. kansasii. These lesions were similar to those that result from infection with M. bovis in WTD. Both M. bovis and M. kansasii are zoonotic. WTD are a reservoir of M. bovis, which is a major concern in regions in which WTD and cattle can come into close contact.

Isolation rates, serovars, and toxin genotypes of nicotinamide adenine dinucleotide-independent Actinobacillus pleuropneumoniae among pigs suffering from pleuropneumonia in Spain.

Actinobacillus pleuropneumoniae is the etiologic agent of swine pleuropneumonia, a major production-limiting disease in the pig industry. In the current study, 2,171 lung specimens obtained from pigs housed in 870 Spanish pig farms in regions of substantial pig production were examined. Conventional microbiology, coupled with species-specific polymerase chain reaction, identified 127 biovar 2 isolates, accounting for 25.3% of all A. pleuropneumoniae (n = 502) detected. Most isolates (79%) were recovered as pure primary cultures or as the predominant bacteria from lungs exhibiting lesions typical of acute swine pleuropneumonia. Coagglutination testing identified the isolates as belonging to serovars 2 (4.7%), 4 (4.7%), 7 (68.5%), and 11 (1.6%); however, 26 isolates were nontypeable. All biovar 2 isolates showed genes of the apxII operon alone, which encodes the corresponding ApxII exotoxin, leading to a different gene pattern for isolates in serovars 2, 4, and 11 compared with those of biovar 1. From this survey, it can be concluded that A. pleuropneumoniae biovar 2 infections are common in pigs in Spain, and they may be a common cause of respiratory disease in swine.

Prevalence of granulomatous pleuropneumonia associated with Actinobacillus pleuropneumoniae serotype 2 in slaughter pigs.

A total of 14,818 slaughtered pigs were examined macroscopically. Of these, 25 pigs with porcine pleuropneumonia were collected and the relations among Actinobacillus spp. and granulomatous lesions in organs (lungs and tonsils) were evaluated. In the lungs, only Actinobacillus pleuropneumoniae serotype 2 was isolated from 20 of the pigs. Histologically, granulomatous pneumonia with A. pleuropneumoniae antigen was detected in 8 of the pigs. The antigen was visible in the centers of the lesions along with asteroid bodies, epithelioid cells and multinucleated giant cells. In the tonsils, granulomatous lesions were not detected, although A. pleuropneumoniae serotype 2 (5 pigs), serotype 7 (1 pig), Actinobacillus porcitonsillarum (1 pig) and Actinobacillus minor (1 pig) were isolated. The present survey suggests that multifocal granulomatous pneumonia in slaughter pigs could be highly associated with A. pleuropneumoniae serotype 2 infection.

Contagious caprine pleuropneumonia - a comprehensive review.

Contagious caprine pleuropneumonia (CCPP) is a serious disease of goats, occasionally sheep and wild ruminants, caused by Mycoplasma capricolum subspecies capripneumoniae (Mccp). The disease is characterized by severe serofibrinous pleuropneumonia, very high morbidity (∼100%), and mortality (80-100%). CCPP affects goats in more than 40 countries of the world thereby posing a serious threat to goat farming around the globe. The characteristic clinical signs of CCPP are severe respiratory distress associated with sero-mucoid nasal discharge, coughing, dyspnea, pyrexia, pleurodynia, and general malaise. In later stages, severe lobar fibrinous pleuropneumonia, profuse fluid accumulation in pleural cavity, severe congestion of lungs and adhesion formation is observed. Mycoplasmal antigen interactions with host immune system and its role in CCPP pathogenesis are not clearly understood. CCPP is not a zoonotic disease. Diagnosis has overcome cumbersome and lengthy conventional tests involving culture, isolation, and identification by advanced serological (LAT, cELISA) or gene-based amplification of DNA (PCR, RFLP, and hybridization) and sequencing. The latex agglutination test (LAT) is rapid, simple, and better test for field and real-time diagnosis applicable to whole blood or serum and is more sensitive than the CFT and easier than the cELISA. Moreover, the studies on antibiotic sensitivity and exploration of novel antibiotics (fluoroquinolones, macrolides) can help in better therapeutic management besides preventing menace of antibiotic resistance. Re-visiting conventional prophylactic measures focussing on developing novel strain-based or recombinant vaccines using specific antigens (capsular or cellular) should be the most important strategy for controlling the disease worldwide.

Update on Actinobacillus pleuropneumoniae-knowledge, gaps and challenges.

Porcine pleuropneumonia, caused by the bacterial porcine respiratory tract pathogen Actinobacillus pleuropneumoniae, leads to high economic losses in affected swine herds in most countries of the world. Pigs affected by peracute and acute disease suffer from severe respiratory distress with high lethality. The agent was first described in 1957 and, since then, knowledge about the pathogen itself, and its interactions with the host, has increased continuously. This is, in part, due to the fact that experimental infections can be studied in the natural host. However, the fact that most commercial pigs are colonized by this pathogen has hampered the applicability of knowledge gained under experimental conditions. In addition, several factors are involved in development of disease, and these have often been studied individually. In a DISCONTOOLS initiative, members from science, industry and clinics exchanged their expertise and empirical observations and identified the major gaps in knowledge. This review sums up published results and expert opinions, within the fields of pathogenesis, epidemiology, transmission, immune response to infection, as well as the main means of prevention, detection and control. The gaps that still remain to be filled are highlighted, and present as well as future challenges in the control of this disease are addressed.

Isolation and molecular characterization of a urease-negative Actinobacillus pleuropneumoniae mutant.

An atypical urease-negative mutant of Actinobacillus pleuropneumoniae serovar 2 was isolated in Japan. Nucleotide sequence analysis of the urease gene cluster revealed that the insertion of a short DNA sequence into the cbiM gene was responsible for the urease-negative activity of the mutant. Veterinary diagnostic laboratories should be watchful for the presence of aberrant urease-negative A. pleuropneumoniae isolates.

New trends in innovative vaccine development against Actinobacillus pleuropneumoniae.

Actinobacillus pleuropneumoniae is the etiological agent of porcine pleuropneumonia, a respiratory disease leading to severe economic losses in the swine industry. The most widely used commercial vaccines are bacterins comprising inactivated whole cells of A. pleuropneumoniae but these have only been partially effective in preventing disease. Innovative immuno-prophylactic preparations of A. pleuropneumoniae based on ApxI, ApxII, ApxIII, ApxIV toxins and outer membrane proteins, among others (i.e. RnhB, GalU, GalT, HflX, ComL, LolB, LppC), have high protective efficacy in mice and pigs. Some vaccine preparations have efficacy against homologous and heterologous A. pleuropneumoniae serovars, which constitute an important advance to control porcine pleuropneumonia. In this arena, subunit vaccines based on toxins are one of the most advanced and promising developments. Many research groups have focussed on the development of live attenuated vaccines comprising strains with inactivated Apx toxins and/or other virulence factors, their protective efficacy being determined in mouse and/or swine models. Other innovative approaches such as bacteria, yeast and plants as production and oral delivery platforms have been explored in animal models and the definitive host with encouraging results. In addition, further research into A. pleuropneumoniae-based DNA and nano-vaccines, as well as bioencapsulation of antigens in plants, is envisaged. Here, the recent findings and future trends in innovative vaccine development against A. pleuropneumoniae are reviewed and placed in perspective.

Listeria monocytogenes-associated respiratory infections: a study of 38 consecutive cases.

OBJECTIVES: Listeria monocytogenes (Lm) is a foodborne human pathogen responsible for severe infections, including septicaemia, neurolisteriosis, and maternal-foetal and focal infections. Little is known about Lm-associated respiratory tract or lung infections. METHODS: We conducted a retrospective study of culture-proven cases of Lm pleural infections and pneumonia reported to the French National Reference Centre for Listeria from January 1993 to August 2016. RESULTS: Thirty-eight consecutive patients with pleural infection (n = 32), pneumonia (n = 5), or both (n = 1) were studied; 71% of these were men. Median age was 72 (range 29-90). Two patients presented with concomitant neurolisteriosis. All patients but one reported at least one immunosuppressive condition (97%), with a median number of 2 (range 0-5), including 29% (8/28) with current exposure to immunosuppressive therapy and 50% (17/34) with ongoing neoplasia; 75% (21/28) reported previous pleural or pulmonary disease. Antibiotic therapy mostly consisted in amoxicillin (72%) associated with aminoglycoside in 32%. Chest-tube drainage was performed in 7/19 patients with empyema (37%); 25% of the patients (7/30) required intensive care management. In-hospital mortality reached 35% and occurred after a median time interval of 4 days (range 1-33 days). Three patients had recurrence of empyema (time interval of 1 week to 4 months after treatment completion). Altogether, only 13/31 patients (42%) diagnosed with Lm respiratory infection experienced an uneventful outcome at 2-year follow-up. CONCLUSION: Lm is a rare but severe cause of pneumonia and pleural infection in older immunocompromised patients, requiring prompt diagnosis and adequate management and follow-up.

Retrospective study of fatal pneumonia in racehorses.

Respiratory diseases have a major impact on racehorses in training and are often cited as the second most common reason of horses failing to perform. Cases were submitted by the California Horse Racing Board to the California Animal Health and Food Safety laboratory for postmortem examination between January 1, 2005 and December 31, 2014. We determined the demographics of racehorses with fatal pneumonia, characterized the pathologic findings in animals with a postmortem diagnosis of respiratory infection, and determined the most significant pathogens associated with lower respiratory tract disease. We analyzed autopsy reports from 83 horses with a diagnosis of pneumonia, bronchopneumonia, and/or pleuropneumonia. The most common presentation was pleuropneumonia (71% of cases), with extensive areas of lytic necrosis and abscesses of the pulmonary parenchyma. Streptococcus equi ssp. zooepidemicus, a normal mucosal commensal of the upper respiratory tract of healthy horses, was the most commonly isolated organism (72% of cases), either in pure culture or accompanied by other aerobic or anaerobic bacteria. Its presence in the pulmonary parenchyma is associated with severe and extensive damage to the lung. Furthermore, this agent has zoonotic potential, which stresses the importance of early detection and proper management of cases of pneumonia in racehorses.

[Varicella: previously healthy children sometimes develop complications]. / Waterpokken: soms complicaties bij voorheen gezonde kinderen.

Three healthy boys, 3.5, 5 and 1.5 years of age, were admitted to hospital with a severe bacterial skin infection, cerebellar ataxia, and pneumonia, respectively, one week after the onset of varicella. They recovered completely after treatment. Studies in Europe report complications from varicella in 2.5% of healthy children. Most of these are neurological complications and secondary bacterial infections of skin and soft tissue. Last year, a European consensus was published that recommended that all healthy children be vaccinated against chickenpox. In The Netherlands, routine varicella zoster virus (VZV) vaccination has not (yet) been implemented. We propose a new discussion on the possible inclusion of VZV vaccination in the national vaccination programme.

Coinfection by Ureaplasma spp., Photobacterium damselae and an Actinomyces-like microorganism in a bottlenose dolphin (Tursiops truncatus) with pleuropneumonia stranded along the Adriatic coast of Italy.

A case of pleuropneumonia is reported in an adult male bottlenose dolphin (Tursiops truncatus) found stranded in 2014 along the Central Adriatic coast of Italy. A severe pyogranulomatous pneumonia and thoracic lymphadenopathy were present at necropsy. Numerous Splendore-Hoeppli bodies were found microscopically scattered throughout the lung. Histochemical evidence of Actinomyces-like organisms was obtained from the pulmonary parenchyma, with a strain of Photobacterium damselae subsp. piscicida and Ureaplasma spp. being also isolated from the same tissue. For the latter, a genome fragment of approximately 1400 bp from the 16s rDNA was amplified and sequenced. BLAST analysis revealed 100% identity with an uncultured Ureaplasma spp. (JQ193826.1).

Streptococcus equi subsp zooepidemicus pleuropneumonia and peritonitis in a dromedary camel (Camelus dromedarius) calf in North America.

CASE DESCRIPTION: A 12-week-old female dromedary camel (Camelus dromedarius) calf was evaluated because of acute (< 24 hours) inappetence and lethargy. The calf was being bottle-fed because of maternal rejection. CLINICAL FINDINGS: Physical examination revealed decreased bronchovesicular sounds and absent borborygmi. The rectal temperature was 38.9°C (102.0°F). A CBC indicated leukopenia with a degenerative left shift suggestive of a systemic infection. Results of abdominal and thoracic ultrasonography showed severe bicavitary effusion, peripheral lung consolidation, and intestinal hypomotility. Pleural and peritoneal fluid analysis confirmed a diagnosis of septic pleuritis and peritonitis. Results of aerobic bacterial culture of venous blood, peritoneal fluid, and pleural fluid samples indicated Streptococcus equi subsp zooepidemicus septicemia as the etiology for the polyserositis (ie, alpaca fever). TREATMENT AND OUTCOME: Treatment with IV broad-spectrum antimicrobials, an NSAID, and pleural drainage was initiated. Clinical signs of pleuropneumonia, peritonitis, and systemic infection improved rapidly 24 hours after initiation of medical treatment. The calf was discharged from the hospital after 11 days, and antimicrobial treatment continued for 2 weeks after discharge. At follow-up approximately 4 weeks after hospital discharge (6 weeks after the initial examination), there were no clinical signs suggestive of relapse or any reported complications. CLINICAL RELEVANCE: S equi subsp zooepidemicus may cause polyserositis in Old World camelids (eg, dromedary camels) with signs similar to those seen in New World camelids (eg, alpaca and llama). The rapid response to medical treatment for the patient described suggested that S equi subsp zooepidemicus-induced polyserositis (alpaca fever) in dromedary camels may respond favorably to appropriate treatment. Reducing stress, reducing overcrowding, and separate housing of equids and camelids are suggested. Further studies are needed to better assess the epidemiology of alpaca fever in dromedary camels in North America.