Increased Serum Antibody Titers Research Articles

Borrelia-like organism in heart capillaries of patient with Lyme-disease seen by electron microscopy

A case of a patient who developed an acute myocarditis due to Lyme disease is reported. An increased serum antibody titer to Borrelia burgdorferi suggested a diagnosis and in addition of basic clinical methods, endomyocardial biopsy performed and analyzed by transmission electron microscopy. The lumen of myocardial capillaries was founded mostly filled with detritus and fibrin precipitate, between them several bacterial fragments were identified. The electron-microscopic characteristics of the microorganisms in this specimen, revealing irregularly coiled appearance and consistent thickness of 0.2 μm, correspond to the spiral-like structure of Lyme disease borrelia. The presence of fibrin deposits on the capillary endothelium and necrosis of myocardiocytes, suggests that the cardiopathy in our patient was represent borrelia-mediated damage of the heart microcirculation.

Prevention of Symptomatic Seasonal Influenza in 2005–2006 by Inactivated and Live Attenuated Vaccines

The efficacy of influenza vaccines may vary annually. In 2004-2005, when antigenically drifted viruses were circulating, a randomized, placebo-controlled trial involving healthy adults showed that inactivated vaccine appeared to be efficacious, whereas live attenuated vaccine appeared to be less so. In 2005-2006, we continued our trial, examining the absolute and relative efficacies of the live attenuated and inactivated vaccines in preventing laboratory-confirmed symptomatic influenza. A total of 2058 persons were vaccinated in October and November 2005. Studywide influenza activity was prolonged but of low intensity; type A (H3N2) virus was circulating, which was antigenically similar to the vaccine strain. The absolute efficacy of the inactivated vaccine was 16% (95% confidence interval [CI], -171% to 70%) for the virus identification end point (virus isolation in cell culture or identification through polymerase chain reaction) and 54% (95% CI, 4%-77%) for the primary end point (virus isolation or increase in serum antibody titer). The absolute efficacies of the live attenuated vaccine for these end points were 8% (95% CI, -194% to 67%) and 43% (95% CI, -15% to 71%), respectively. With serologic end points included, efficacy was demonstrated for the inactivated vaccine in a year with low influenza attack rates. The efficacy of the live attenuated vaccine was slightly less than that of the inactivated vaccine, but not statistically greater than that of the placebo.

Diagnosis and treatment of Q fever: attempts to clarify current problems in Japan

"Q fever" is a generic term for infection caused, mostly in the form of pneumonia or bronchitis, by Coxiella burnetii (Q-fever Coxiella), a pathogen closely related to Rickettsia and Legionella. Q fever is an influenza-like, transient febrile infectious disease that is common to humans and animals; it develops after the transmission of the infectious agent from livestock or pet animals, but person-to-person transmission is rare. In Europe and the United States, it is ranked fourth or fifth as an underlying cause of community-acquired pneumonia. Many patients with Q fever have a good prognosis, and their mortality is about 1%-2% when left untreated. However, because some patients may take a long time to be cured or may have a chronic condition with poor prognosis, patients with definitely diagnosed Q fever or those strongly suspected of having Q fever are strongly recommended to receive treatment. The definite diagnosis of Q fever is made based on a significant increase in serum antibody titers, the determination of which often requires considerable time, and therefore patients must be monitored for a certain period. Q-fever Coxiella, an obligate intracellular parasite, is basically not susceptible to beta-lactam antibiotics, which barely permeate into the cells, but the parasite is susceptible to tetracyclines, macrolides, and quinolones, with these agents being sufficiently permeable into the cells. However, there are many cases of spontaneous cure, and it is likely that beta-lactam treatment may have been involved in these cases. Vaccination against Q fever is not common in Japan.

Vaccinating Calves

For decades, veterinarians have believed that young animals with circulating maternally-derived antibody cannot be effectively vaccinated. However, many investigators have shown that young animals vaccinated in the face of maternal antibody (IFOMA), while not showing evidence of an increase in serum antibody titer typically seen in older animals responding to vaccination, will show evidence of T cell activation or, better yet, protection from disease when they are exposed to infection after maternal antibodies have disappeared. Successful priming for a memory immune response by vaccination IFOMA has repeatedly been shown to be possible in calves. In general, successful vaccination of calves with moderate levels of maternal antibody requires two doses of modified-live vaccine given at least 2-4 weeks apart, but exceptions to this rule have been identified. While two doses are more likely to be successful, in some cases it has been possible to protect calves from disease months later by vaccination with a single dose of modified-live vaccine given intranasally or parenterally when they are within two months of age. However, these findings are not consistent; occasionally young animals vaccinated IFOMA fail to develop a protective immune response to later challenge. Reasons that calves are often but not always successfully protected when vaccinated IFOMA are not completely defined, but are likely related to age of the animal at vaccination, amount of maternal antibody present, type of vaccine the calf receives, virulence of the challenging pathogen, and the outcome used to define success of vaccination. While more research is needed before consistently reliable recommendations for successful vaccination of calves IFOMA can be made, ample evidence suggests that vaccination IFOMA can protect calves from disease when they are exposed to infectious agents after maternal antibodies have disappeared in at least some cases. Thus, vaccination IFOMA may be worthwhile and cost effective practice when young calves are at reasonably high risk of disease due to agents for which effective vaccines are available.

InactivatedFrancisella tularensisLive Vaccine Strain Protects against Respiratory Tularemia by Intranasal Vaccination in an Immunoglobulin A-Dependent Fashion

Francisella tularensis is a gram-negative intracellular bacterium that is considered to be a potential category A biological weapon due to its extreme virulence. Although vaccination with the attenuated live vaccine strain (LVS) of F. tularensis can protect against lethal challenge, use of inactivated or subunit forms as vaccine candidates for induction of protective antibody responses has not been fully evaluated. In the present study, we examined whether immune protection in the lung could be stimulated by intranasal administration of inactivated LVS together with interleukin-12 (IL-12) as an adjuvant. LVS was inactivated by heat, paraformaldehyde treatment, or exposure to UV, and inactivation of the preparations was confirmed by assessing bacterial growth and the survival of mice after direct inoculation. We found that mucosal vaccination with inactivated LVS provided 90 to 100% protection in mice after lethal intranasal challenge with 10(4) CFU of LVS, and this protection was dependent on inclusion of exogenous IL-12 during vaccine administration. Survival of vaccinated mice after live bacterial challenge was correlated with reduced bacterial burden, decreased pulmonary inflammation, increased serum antibody titers, and lower levels of gamma interferon (IFN-gamma), tumor necrosis factor alpha, and IL-6 in the lungs, livers, and spleens. Whereas NK cells were primarily responsible for the production of IFN-gamma in unvaccinated, challenged animals, vaccinated mice had increased levels of lung IFN-gamma+ CD4+ T cells after challenge. Significantly, mice genetically deficient in immunoglobulin A (IgA) expression were unable to survive lethal challenge after vaccination. These results are the first results to demonstrate that IgA-mediated protection against lethal respiratory tularemia occurs after mucosal vaccination with inactivated F. tularensis LVS.

LEE-encoded regulator (Ler) mutants elicit serotype-specific protection, but not cross protection, against attaching and effacing E. coli strains

We previously showed that single dose orogastric immunization with an attenuated regulatory Lee-encoded regulator ( ler) mutant of the rabbit enteropathogenic Escherichia coli (REPEC) strain E22 (O103:H2) protected rabbits from fatal infection with the highly virulent parent strain. In the current study we assessed the degree of homologous (serotype-specific) and heterologous (cross-serotype) protection induced by immunization with REPEC ler mutant strains of differing serotypes, or with a prototype strain RDEC-1 (O15:H-) which expresses a full array of ler up-regulated proteins. We constructed an additional ler mutant using RDEC-1 thus, permitting immunization with a ler mutant of either serotype, O15 or O103, followed by challenge with a virulent REPEC strain of the same or different serotypes. Consistent with our previous data, the current study demonstrated that rabbits immunized with a RDEC-1 ler mutant were protected from challenge with virulent RDEC-H19A (RDEC-1 transduced with Shiga toxin-producing phage H19A) of the same serotype. Rabbits immunized with RDEC-1 or E22 derivative ler mutants demonstrated significant increase in serum antibody titers to the respective whole bacterial cells expressing O antigen but not to the LEE-encoded proteins. However, immunization with the ler mutants of either E22 or RDEC-1 failed to protect rabbits from infections with virulent organisms belonging to different serotypes. In contrast, rabbits immunized with the prototype RDEC-1 were cross protected against challenge with the heterologous E22 strain as shown by normal weight gain, and the absence of clinical signs of disease or characteristic attaching and effacing (A/E) lesions. Immunization with RDEC-1 induced significantly elevated serum IgG titers to LEE-encoded proteins. We thus, demonstrated homologous protection induced by the REPEC ler mutants and heterologous protection by RDEC-1. The observed correlation between elevated immune responses to the LEE-encoded proteins and the protection against challenge with heterologous virulent REPEC strain suggests that serotype-non-specific cross protection requires the expression of, and induction of antibody to, LEE-encoded virulence factors.

Oral immunization of Carassius auratus with modified recombinant A-layer proteins entrapped in alginate beads

This study was focused on the utilization of a recombinant expression system to produce a unique modified subunit vaccine possessing a self-contained delivery system which could potentially improve the uptake and delivery of vaccine products as well their immunogenic potential. For this purpose the A-layer protein (At-R) associated with the fish pathogen atypical Aeromonas salmonicida was cloned and modified by the genetic fusion of the protein transduction domain (MTS) derived from Kaposi fibroblast growth factor (At-MTS). The potential for these proteins to be employed as antigens for oral immunization of goldfish was examined by encapsulation of At-R, At-MTS and the control, BSA, into biodegradable alginate gel macrospheres which were fed to goldfish in place of standard pellet fish feed. The bead physical properties were modified only in the presence of At-R and the temporal release of proteins was significantly less when At-MTS was employed. Western blot analysis of serum samples collected from fish following intubation with the recombinant proteins determined that the rate of protein uptake from the digestive tract into the blood system improved considerably when MTS was fused to At-R. Experimental fish were fed one of three protein–alginate formulae on a schedule of 3 days/week or 5 days/month for a period of 2 months. After 1 month, animals fed on the 5-day protocol demonstrated increased serum antibody titers while following an additional month of feeding this level decreased and titers were found to be higher in fish maintained on the 3-day regime. Fish fed At-MTS maintained the highest titer at the end of 2-month period. To determine whether the diminished antibody titers were a result of oral tolerance fish were injected intraperitoneally with the At-R antigen. Only experimental groups which had been fed At-R or At-MTS demonstrated increased antibody titers which paralleled a typical secondary humoral response. In spite of the presence of an increased titer to A-protein, vaccinated fish did not demonstrate resistance to infection with atypical A. salmonicida.

Recombinant Streptococcus equi proteins protect mice in challenge experiments and induce immune response in horses.

Horses that have undergone infection caused by Streptococcus equi subspecies equi (strangles) were found to have significantly increased serum antibody titers against three previously characterized proteins, FNZ (cell surface-bound fibronectin binding protein), SFS (secreted fibronectin binding protein), and EAG (alpha2-macroglobulin, albumin, and immunoglobulin G [IgG] binding protein) from S. equi. To assess the protective efficacy of vaccination with these three proteins, a mouse model of equine strangles was utilized. Parts of the three recombinant proteins were used to immunize mice, either subcutaneously or intranasally, prior to nasal challenge with S. equi subsp. equi. The adjuvant used was EtxB, a recombinant form of the B subunit of Escherichia coli heat-labile enterotoxin. It was shown that nasal colonization of S. equi subsp. equi and weight loss due to infection were significantly reduced after vaccination compared with a mock-vaccinated control group. This effect was more pronounced after intranasal vaccination than after subcutaneous vaccination; nearly complete eradication of nasal colonization was obtained after intranasal vaccination (P < 0.001). When the same antigens were administered both intranasally and subcutaneously to healthy horses, significant mucosal IgA and serum IgG antibody responses against FNZ and EAG were obtained. The antibody response was enhanced when EtxB was used as an adjuvant. No adverse effects of the antigens or EtxB were observed. Thus, FNZ and EAG in conjunction with EtxB are promising candidates for an efficacious and safe vaccine against strangles.

Effects of vaccination prior to transit and administration of florfenicol at time of arrival in a feedlot on the health of transported calves and detection of Mannheimia haemolytica in nasal secretions.

To determine effects of vaccination prior to transit and prophylactic administration of florfenicol at time of arrival at a feedyard on health of cattle and colonization of the nasopharynx by Mannheimia haemolytica (MH). 121 steers from Tennessee and 84 steers from New Mexico. Half of the steers were vaccinated before transport to a feedyard. Steers from Tennessee were vaccinated with MH bacterin-toxoid, and steers from New Mexico were vaccinated intranasally with modified-live leukotoxin-deficient MH. Half of the vaccinates and nonvaccinates were randomly selected to receive florfenicol on arrival at the feedyard. Steers were observed daily for respiratory tract disease (RTD). Administration of florfenicol at time of arrival reduced the incidence of RTD, delayed the interval before onset of RTD, and reduced the incidence of MH colonization of the nasopharynx for at least 4 days, but vaccination did not have any effect. Vaccination elicited an increase in serum antibody titers to MH. Administration of florfenicol at time of arrival reduced the development of serum antibody titers in intranasally vaccinated steers and both groups of nonvaccinated steers, but intranasal vaccination did not affect colonization by wild-type MH. Administration of florfenicol at time of arrival decreased the incidence of MH organisms in the nasopharynx and delayed the onset of RTD. Prophylactic use of suitable antibiotics is likely to reduce the incidence of acute RTD in calves for several days after arrival at feedyards, which is the period when they are most susceptible to infectious organisms.

Formation of morphine tolerance in offspring of morphine-tolerant animals: neurochemical and neuroimmune correlates.

We carried out a complex physiological, neurochemical, and neuroimmunologic study of the formation of tolerance to analgetic effect of morphine and analyzed enkephalinase A activity in different brain structures and serotonin antibodies in the serum. More early development of morphine tolerance and a sharp increase in serum antibody titer was found in the offspring of morphine-tolerant rats. This points to an imbalance in the neurotransmitter system and can serve as a diagnostic marker of endogenous opioid system pathology.

Effects of vaccinating beef dams precalving and calves preweaning with a Pasteurella haemolytica vaccine (2001)

Our objective was to determine if vaccinating dams precalving and calves preweaning for Pasteurella haemolytica could effect serum antibody titers in dams, and the pre- and post-weaning health and performance of their calves. Vaccination increased serum antibody titers in multiparous cows, but not first-calf heifers. Precalving vaccination had minimal effects on mortality and morbidity of calves before or after weaning. Subsequent steer feedlot gains were unaffected by precalving and preweaning vaccinations and carcasses were not affected. However, heifers' weight gains were greater from weaning to one year of age when reared by vaccinated dams.

Acute Q fever in adult patients: report on 63 sporadic cases in an urban area.

We report here 63 sporadic urban cases of acute Q fever diagnosed in 1985-1997. Fifty-eight men and five women were included; the mean age (+/- SD) was 35.6 (+/- 10.2) years. Twenty-six patients had pneumonia, 30 had hepatitis, and 7 had a self-limited febrile illness. The most frequent radiological abnormalities were lobar or segmental alveolar opacities involving right lower lobes. Chronic bronchitis was significantly more frequent among patients with pneumonic Q fever (P = .01). Thirty-two patients' illnesses were diagnosed through seroconversion, 12 by a fourfold increase in serum antibody titer, and 19 by initial high titers. Patients who initially received doxycycline had a significantly shorter duration of fever than those treated with erythromycin or other antibiotics (P = .0001 and P = .0004, respectively). No patient died. Acute Q fever affects mainly urban men, most frequently causing hepatitis, except in those with chronic bronchitis, who more frequently develop pneumonia. Hepatic Q fever presented with more pronounced increases in liver function test values than did pneumonic Q fever. Treatment with doxycycline caused a significant reduction in the duration of fever.

Serologic responses of young colostrum fed dairy calves to antigens of Pasteurella haemolytica A1

The potential and limitations of early calfhood vaccination to induce active immunity to Pasteurella haemolytica A1 in conventional colostrum fed calves were investigated. Holstein dairy calves ( n = 29) were vaccinated at 2 and 4 weeks of age, or at 6 and 8 weeks of age with a commercial culture supernatant vaccine (Presponse ®, Langford Inc., Guelph, Ont., Canada), or remained unvaccinated as controls. Serum antibody titres were measured using an indirect bacterial agglutination assay, a leukotoxin neutralization assay, and enzyme immunoassays for antibodies of the IgM, IgG1, and IgG2 isotypes binding purified capsular polysaccharide of P. haemolytica A1. Seroconversion (fourfold or greater increase in serum antibody titre) rates were compared using Fisher's exact test. The effects of passive antibody titres and age on response to vaccination were assessed by linear modelling. Vaccination at 2 and 4 weeks of age was associated with 40%, and 0% of calves seroconverting on the basis of agglutinating antibody titres, and leukotoxin neutralizing titres respectively, and 50%, 0%, and 0% seroconverting on the basis of IgM, IgG1 and IgG2 antibodies to capsular polysaccharide, respecitively. Agglutinating antibody responses were not related to prevaccination antibody titres, or to age at vaccination. Higher responses ( p = 0.08) to leukotoxin were observed in older calves (after taking differences in prevaccination titres into account). Statistical analyses of responses to capsular polysaccharide among calves with comparable prevaccination IgG1 antibody titres revealed significantly higher IgM, IgG1 and IgG2 responses in older calves. Rising titres of IgM antibodies in nonvaccinated calves after 5 weeks of age suggest natural exposure to P. haemolytica A1 or antigens which result in serologic cross-reactions as a means of priming immune responses.

A murine model of accelerated periodontal disease in diabetes.

Diabetes is a risk factor for periodontal disease in humans. In hyperglycemia, glycoxidation of proteins and lipids results in the formation of advanced glycation endproducts, or AGEs. The accumulation of AGEs in the plasma and tissues, and their interaction with their cellular receptor for AGE (RAGE), has been implicated in diabetic complications. In order to establish a model with which to delineate the specific host response factors that underlie the development of periodontal disease in diabetes, male C57BL/6J mice were rendered diabetic with streptozotocin. One month after documentation of diabetes or control state, mice were inoculated with the human periodontal pathogen Porphyromonas gingivalis, strain 381 (P. gingivalis) or treated with vehicle. Infection with P. gingivalis was achieved, as demonstrated by infiltration of gingival tissue with granulocytes, presence of DNA specific for P. gingivalis as well as increased serum antibody titer to P. gingivalis. At 2 and 3 months after infection, increased alveolar bone loss was demonstrated in P. gingivalis-inoculated diabetic vs. non-diabetic mice, along with enhanced tissue-destructive capacity, as demonstrated by increased collagenolytic activity in gingival extracts. Consistent with an important role for AGE-RAGE interaction, increased AGE deposition and expression of vascular and monocyte RAGE were demonstrated in diabetic gingiva compared with non-diabetic controls. Taken together, these data indicate that we have established a murine model of enhanced periodontal disease in diabetes. This model will serve to delineate molecular mechanisms which account for the increased susceptibility of diabetic patients to periodontal disease.

Serum and skin surface antibodies and their associations with sheep biting lice, Bovicola ovis, on experimentally infested sheep.

The sheep biting louse (Bovicola ovis) feeds superficially on the skin of sheep but appears to stimulate an immune response. In this study we examined the association between louse infestation and serum and skin surface antibodies. Louse numbers were monitored on experimentally infested Polypay and Columbia ewes for two years and on their lambs in the second year. Serum and skin wash samples were tested for antibodies to soluble extracts of B. ovis, Stomoxys calcitrans and Musca autumnalis by enzyme linked immunosorbent assay (ELISA). In addition, the effects of skin wash extracts on B. ovis were examined in vitro. The titre of anti-B. ovis antibodies in the serum did not differ significantly between infested and naive ewes. However, there was an increase in serum antibody titre which coincided with periods of high louse density in ewes with high louse counts. Infested lambs had higher serum antibody levels than naive lambs. Substantial cross reactivity was evident among extracts of the different insects. Densities of lice on the ewes during population decline were negatively related to the titre of skin surface antibodies. Skin washings collected from sheep during B. ovis population decline reduced the number of louse progeny when incorporated into louse diet. These results indicate that B. ovis stimulates an immune response in sheep and suggest that compounds on the skin surface may play a role in the regulation of louse populations.

Molecular characterization of two Bordetella bronchiseptica strains isolated from children with coughs.

During a surveillance program associated with the Italian clinical trial for the evaluation of new acellular pertussis vaccines, two bacterial isolates were obtained in cultures of samples from immunocompetent infants who had episodes of cough. Both clinical isolates were identified as Bordetella bronchiseptica by biochemical criteria, although both strains agglutinated with antisera specific for Bordetella parapertussis, suggesting that the strains exhibited some characteristics of both B. bronchiseptica and B. parapertussis. Both children from whom these strains were isolated exhibited an increase in serum antibody titer to pertussis toxin (PT), a protein that is produced by Bordetella pertussis but that is not thought to be produced by B. bronchiseptica. We therefore examined whether the clinical isolates were capable of producing PT. Neither strain produced PT under laboratory conditions, although both strains appeared to contain a portion of the ptx region that encodes the structural subunits of PT. In order to determine whether the ptx genes may encode functional proteins, we inserted an active promoter directly upstream of the ptx region of one of these strains. Biologically active PT was produced, suggesting that this strain contains the genetic information necessary to encode an active PT molecule. Sequence analysis of the ptx promoter region of both strains indicated that, while they shared homology with the B. bronchiseptica ATCC 4617 sequence, they contained certain sequence motifs that are characteristic of B. parapertussis and certain motifs that are characteristic of B. pertussis. Taken together, these findings suggest that variant strains of B. bronchiseptica exist and might be capable of causing significant illness in humans.

Population dynamics of bovine herpesvirus 1 infection in a dairy herd

An induced outbreak of a bovine herpesvirus 1 (BHV1) infection in a dairy herd is described. The outbreak was induced by injecting three BHV1 seropositive cows with dexamethasone. Within 7 weeks all seronegative cows had seroconverted. Also some seropositive animals showed a significant increase in serum antibody titre. Using these data, parameters of population dynamics such as R 0, the basic reproduction ratio, could be estimated. The basic reproduction ratio is a threshold value describing infection dynamics in a population. This parameter is defined as the average number of secondary cases generated by one primary case in a wholly susceptible population of defined density. In this population R 0 was estimated to be at least 7. The importance of these findings, and implications for eradication of BHV1 are discussed.

Diagnosis of respiratory virus infections using GACELISA of urinary antibodies

Sensitive and specific methods are needed to diagnose respiratory virus infections using body fluids such as urine that, unlike blood samples, are readily obtained by non-invasive means. Immunoglobulin G antibody capture enzyme-linked immunosorbent assays were developed for detection of antibody rises to respiratory syncytial virus and influenza A/Taiwan 3H1N1) after initial quantification and adjustment of urinary IgG concentration. Of 24 elderly subjects whose sera were assayed by the complement fixation test for antibody to RSV, seven had convalescent titres ≥ 32, and five had ≥ 4-fold rises in titre. Acute and convalescent urines for six of these seven subjects were tested for virus-specific urinary IgG by GACELISA. Four of four persons with ≥ 4-fold rises in CFT had urine ELISA convalescent to acute ratios of ≥ 1.8 whereas two subjects with convalescent CF titres > 16, but no increase in serum antibody titre, had urine convalescent/acute ratios of 1.0. Ten subjects with ≥ 4-fold rises in CFT or HI antibodies to influenza A/Taiwan had urine ELISA ratios of ≥ 1.4 when samples taken on the day of influenza vaccination and 16 days later were compared. These preliminary observations demonstrate clinically significant rises in respiratory pathogen antibody levels between acute and convalescent urine samples, provided that total urinary IgG concentrations are quantified and then standardised.

Preparturient vaccination to enhance passive immunity to the capsular polysaccharide of Pasteurella haemolytica A1

The potential to increase passive serum antibody titres to a polysaccharide antigen in neonates, by preparturient vaccination of the dams was investigated. Dairy cows in five private herds were vaccinated with a commercial Pasteurella haemolytica culture supernatant vaccine (Presponse 09, Langford Inc.), at 6 and 3 weeks before their calculated due dates. Dams' sera, colostral whey, and post-colostral calf sera were assayed for antibodies of the IgG1 isotype binding purified capsular polysaccharide of P. haemolytica A1, using an enzyme immunoassay. Antibody titres were analyzed using the General Linear Model procedure (Statistical Analysis Systems Institute Inc.). Vaccinated dams had a significant increase in serum antibody titre after vaccination compared with non-vaccinates ( P < 0.01), and their antibody titres in colostral whey were significantly higher ( P < 0.05). Calves of vaccinated dams had significantly higher passive antibody titres than those of non-vaccinates ( P < 0.01) in all herds.

Rickettsialpox in a New York City hospital, 1980 to 1989.

Rickettsialpox is caused by Rickettsia akari, which is transmitted from rodents to humans by bloodsucking mites. The initial skin lesion forms an eschar and is followed by the development of fever, malaise, myalgia, and 5 to 40 maculopapules and papulovesicles. The disease, which responds to tetracycline, can be mistaken for chickenpox. The diagnosis has been based on an increase in serum antibody titers against R. akari over a period of three to eight weeks. We discuss a more rapid technique that uses direct immunofluorescence to identify R. akari in paraffin-embedded tissue, and we describe the histopathological findings of lesional skin. We studied 13 patients (age, 11 months to 58 years) who were seen at Lincoln Hospital in New York City from 1980 to 1989 and were suspected of having rickettsialpox. In nine patients serum samples were obtained during the acute and convalescent phases of the illness for indirect fluorescent-antibody testing. Punch-biopsy specimens of skin lesions were examined by microscopy and by direct fluorescent-antibody testing with an anti-R. rickettsii globulin conjugated with fluorescein isothiocyanate. The diagnosis was confirmed in all 13 patients by indirect or direct fluorescent-antibody techniques. Direct fluorescent-antibody testing of eschars from seven patients was positive in five patients, but negative in two patients who had serologically confirmed rickettsialpox. In contrast, direct fluorescent-antibody testing of papulovesicles from nine patients was positive in only one patient. Histopathological analysis of the eschars revealed extensive necrosis and inflammation. In biopsy specimens of papulovesicles, dermal edema, subepidermal vesicles, and vascular changes were present. The combination of direct fluorescent-antibody testing of an eschar from the presumed site of inoculation and histopathological examination of papulovesicles for distinctive features represents an improved method of diagnosing rickettsialpox.