Trends in clinical diagnoses of typhus group rickettsioses among a large U.S. insurance claims database

Typhus group rickettsioses (TGRs) are vector‐borne diseases that include murine typhus (Rickettsia typhi) and epidemic typhus (R. prowazekii). Twentieth‐century public health interventions led to dramatic decreases in incidence; little is known about the contemporary TGR prevalence because neither disease is nationally notifiable. We summarized administrative claims data in a commercially insured population to examine trends in TGR medical encounters. We analysed data from 2003 to 2016 IBM® MarketScan® Commercial Databases to identify persons with inpatient or outpatient visits with an International Classification of Diseases, Ninth or Tenth Revision, Clinical Modification TGR‐specific code. We summarized epidemiologic characteristics associated with incident diagnosis. We identified 1,799 patients diagnosed with a TGR. Patients resided in 46 states, and most were female (n = 1,019/1,799; 56.6%); the median age was 42 years (range: 0–64 years). Epidemic typhus (n = 931/1,799; 51.8%) was the most common TGRs, followed by murine typhus (n = 722/1,799; 40.1%). The majority of TGR patients were diagnosed in an outpatient setting (n = 1,725/1,799; 95.9%); among hospitalized patients, the majority received a murine typhus diagnosis (n = 67/74; 90.5%). TGRs are rarely diagnosed diseases. More patients were diagnosed with epidemic than murine typhus, even though R. prowazekii transmission requires body louse or flying squirrel exposure. Patients from all geographic regions were diagnosed with murine and epidemic typhus, despite historically recognized ranges for these diseases. The epidemiologic misalignment of insurance claims data versus historic TGRs data highlights the challenges of finding appropriate alternative data sources to serve as a proxy when national surveillance data do not exist.     

Serologic evidence of avian influenza H9N2 and paramyxovirus type 1 infection in emus (Dromaius novaehollandiae) in India

An avian influenza (AI) surveillance was undertaken in Maharashtra state, India during the period 2010-2011. There are no reports of AI surveillance in emus from India. A total of 202 blood samples and 467 tracheal and cloacal swabs were collected from eight emu farms. A hemagglutination inhibition (HI) assay was performed for detection of antibodies against AI H5N1, H7N1, H9N2, and avian paramyxovirus type 1 (APMV-1) viruses. A microneutralization (MN) assay was performed to confirm the presence of neutralizing antibodies against AI H9N2 and to compare with HI assays. A total of 28.2% and 28.7% of samples were positive for antibodies against AI H9N2 by HI and MN assays, respectively, using > or = 1:40 as a cut-off titer; 15.3% samples were positive for APMV-1 by HI assay using a > or = 1:10 cut-off titer. Seropositivity of AI H9N2 was nil in the grower (<1 yr) age group and highest (78%) in the breeder (2-3 yr) age group, whereas seropositivity against APMV-1 was observed in all age groups. Performance of both HI and MN assays was similar, suggesting the utility of using the MN assay along with HI assay for surveillance studies. This is the first report of the seroprevalence of AI H9N2 and APMV-1 in emus in India.     

Prevalence of Bartonella henselae antibodies in serum of cats with and without clinical signs of central nervous system disease

Bartonella henselae is occasionally associated with neurological dysfunction in people and some experimentally infected cats. The purpose of this study was to determine whether B henselae seroprevalence or titer magnitude varies among cats with neurological disease, cats with non-neurological diseases, and healthy cats while controlling for age and flea exposure. There was no difference in B henselae seroprevalence rates between cats with seizures and cats with other neurological diseases. Cats with non-neurological disease and healthy cats were more likely than cats with neurological disease to be seropositive. While the median B henselae antibody titer was greater in cats with seizures than in cats with other neurological disease, the median B henselae antibody titer was also greater in healthy cats than cats with seizures. The results suggest that titer magnitude cannot be used alone to document clinical disease associated with B henselae infection and that presence of B henselae antibodies in serum of cats with neurological disease does not prove the clinical signs are related to B henselae.     

Serological survey of vector-borne zoonotic pathogens in pet cats and cats from animal shelters and feral colonies

Although cats and their arthropod parasites can sometimes be important sources of zoonotic diseases in humans, the extent of exposure among various cat populations to many potential zoonotic agents remains incompletely described. In this study, 170 domestic cats living in private homes, feral cat colonies, and animal shelters from California and Wisconsin were evaluated by serology to determine the levels of exposure to a group of zoonotic vector-borne pathogens. Serological positive test results were observed in 17.2% of cats for Rickettsia rickettsii, 14.9% for R akari, 4.9% for R typhi, 11.1% for R felis, and 14.7% for Bartonella henselae. Although vector-borne disease exposure has been documented previously in cats, the evaluation of multiple pathogens and diverse cat populations simultaneously performed here contributes to our understanding of feline exposure to these zoonotic pathogens.     

Surveys of rodent‐borne disease in Thailand with a focus on scrub typhus assessment

The epidemiology of many rodent‐borne diseases in South‐East Asia remains ill‐defined. Scrub typhus and lep‐tospirosis are common and medically significant, while other zoonotic diseases, such as spotted fever group Rickettsiae have been identified, but their overall medical significance is unknown. Rodent surveillance was conducted from June 2002 to July 2004 in 18 provinces from Thailand. Traps were set up for one to three nights. Blood and serum samples and animal tissue samples (liver, spleen, kidney and urinary bladder) were collected. Chiggermites, ticks and fleas were removed from captured rodents. A total of 4536 wild‐caught rodents from 27 species were captured over two years of animal trapping. Rattus rattus was the dominant species, followed by Rattus exulans and Bandicota indica. Almost 43 000 ectoparasites were removed from the captured animals. Approximately 98% of the ectoparasites were chigger‐mites, of which 46% belonged to the genus Leptotrombidium (scrub typhus vector). Other genera included Schoengastia and Blankaartia. Tick and flea specimens together comprised less than 1% of the sample. Among the five species of ticks collected, Haemaphysalis bandicota was the predominant species caught, followed by Ixodes granulatus other Haemaphysalis spp., Rhipicephalus spp. and Dermacentor spp. Only two species of fleas were collected and Xenopsylla cheopis (rat flea) was the predominant species. Using both commercial diagnostic kits and in‐house molecular assays, animal tissue samples were examined and screened for zoonotic diseases. Seven zoonotic diseases were detected: scrub typhus, leptospirosis, murine typhus, tick typhus, bartonella, babesiosis and trypanosomiasis. Most samples were positive for scrub typhus. Other zoonotic diseases still under investigation include borrelosis, ehrlichiosis, the plague, and other rickettsial diseases. Using geographic information systems, global positioning systems and remote sensing technology, epidemiological and environmental data were combined to assess the relative risk in different biotopes within highly endemic areas of scrub typhus in Thailand.     

Ovine anti-rabies antibody production and evaluation

In view of the disadvantages of human and equine rabies immunoglobulin still there is urgent needs for safe and cost-control anti-rabies immunoglobulins especially for person who have been severely exposed (categories III) to the virus. Our attempt to produce a less immunogenic and cheaper anti-rabies immunoglobulin affordable for those people living in developing countries, has been harnessed the ovine as a bioreactor instead the horse. The animals have been intramuscular immunized, and the plasma processed with 5% caprylic acid to yield IgG with purity of 95%. Moreover, antibody apparently indicated that the titer and neutralizing indexes were harmonized, especially at higher antibody dilution. The results showed that three immunized sheep were produced about 7000 IU of purified anti-rabies antibody. Sheep's IgG has low immunogenic effect than human and horse antibodies when injected into the mouse. Pure concentrated ovine antibody may serve as a possible alternative to currently available anti-rabies human or equine immunoglobulin.     

Adaptation of enzyme-linked immunoassay for detection of avian and murine antibodies to Eimeria

The enzyme-linked immunosorbent assay (ELISA) was adapted to detect antibodies to Eimeria. Avian serum antibodies were easily demonstrated and were comparable in titer to indirect fluorescent-antibody (IFA) test levels reported by others. Hybridoma-produced murine antibodies were also detected by ELISA.     

Determination of IgM and IgG antibodies to Toxoplasma using the IFA test, ELISA, and Dot-ELISA procedures

The dot enzyme-linked immunosorbent assay (Dot-ELISA) and the enzyme-linked immunosorbent assay (ELISA) were compared with the immunofluorescent antibody test (IFA) for detection of IgM- and IgG-specific antibodies to human toxoplasmosis. Reciprocal titers were determined in all three assays using sera from 56 patients with suspected toxoplasmosis or with symptoms and diseases requiring exclusion of toxoplasmosis and control sera from 56 healthy persons. Using the Dot-ELISA, six patient sera (10.7%) were positive at titers of greater than equal to 1024 for IgM antibodies (titer range 1024-16 384) and 47 sera (84%) were positive for IgG antibodies (titer range 16-262 144) at a titer of greater than or equal to 16. One control serum was reactive for IgM (titer 1024) and 10 control sera (18%) were positive for IgG in the Dot-ELISA. In the ELISA, at titers of greater than or equal to 128, five sera (9%) were reactive for IgM (titer range 128-512) and 52 sera (92.8%) were reactive for IgG (titer range 32-8192) at a titer of greater than or equal to 32; no control sera gave positive reactions for IgM while 10 sera (18%) were positive for IgG in the ELISA. Using the IFA test at reciprocal titers of greater than or equal to 16, four sera (7.1%) were positive for IgM (titer range 32-512), and 51 sera (91%) were positive for IgG (titer range 16-8192). None was reactive for IgM, and eight sera (14%) were positive for IgG (titer range 32-128) in the IFA test. The Dot-ELISA correlated well with the IFA test (correlation coefficient = 0.895) and the ELISA correlated slightly higher with the IFA test (correlation coefficient = 0.910) for detection of IgG antibodies to Toxoplasma gondii.     

Stability of attenuated live virus rabies vaccine in baits targeted to wild foxes under operational conditions

The viability of an attenuated live virus rabies vaccine in a bait targeted to red foxes was examined under various operational conditions in a series of experiments in Ontario. The virus was relatively stable over a 28-day period in the field, losing a mean 0.5, s = 0.2 log10 of virus titer. The micro-environment into which the bait was placed (open cultivated field, grassy meadow, wooded grove, sun or shade) did not make an appreciable difference in the viability of the virus. There was no significant difference (P < or = 0.05) between mean ambient temperatures and the temperature of fluids in blister packs of baits placed in sun or shade. Sixty-three percent of foxes fed baits exposed to sun and shade conditions for 21 days (titer 10(6.2) tissue culture infective doses per 1 mL) developed rabies virus-neutralizing antibodies. Storage of vaccine baits at -30 degrees C prior to bait distribution was important in maintaining virus viability.     

A Cross‐Sectional Study of Hepatitis E Virus Infection in Healthy People Directly Exposed and Unexposed to Pigs in a Rural Community in Northern Thailand

A cross‐sectional study of the association between occupational pig exposure and hepatitis E virus (HEV) infection in adult pig farmers and the general population who were not directly exposed to pigs was conducted in Nan Province, Thailand, from November 2010 to April 2011. All participants were interviewed to provide information on their job history, eating habits and other potential confounders. The prevalence of anti‐HEV immunoglobulin G antibodies (IgG) among 513 subjects was 23.0%. Hand washing with water and soap was associated with a lower seroprevalence of HEV infection, whereas living in an area with frequent flooding (OR 1.64, 95% CI: 1.00–2.68) and consuming internal pig organs more than twice per week (OR 3.23, 95%CI: 1.15–9.01) were both associated with a higher seroprevalence of anti‐HEV IgG. There was no association between HEV seroprevalence and frequent, direct occupational pig contact.     

Pronghorn Winter Resource Selection Before and After Wind Energy Development in South-Central Wyoming

Few studies have evaluated the response of ungulate populations to wind energy development. Recent demand for wind-generated electricity coupled with a tendency for wind-energy facilities to be sited within suitable pronghorn (Antilocapra americana) winter range make this a critical issue for conservation of this icon of western North America. We evaluated pronghorn response to wind energy development at the winter home range scale, as well as within individual winter home ranges using data collected from 47 adult female pronghorn equipped with Global Positioning System transmitters. At both scales, we developed separate resource selection models for pronghorn before (winter 2010) and after (winters 2011 and 2012) development of the Dunlap Ranch wind energy facility in south-central Wyoming to evaluate the potential impacts of wind energy infrastructure on pronghorn winter resource selection. In general, pronghorn winter resource selection was correlated with greater sagebrush (Artemisia spp.) cover, lower snow depth, and lower slopes before and after wind energy development at both scales. At the larger scale, pronghorn selected home ranges closer to wind turbines during all winters. Within home ranges, pronghorn selected areas closer to future locations of wind turbines at Dunlap Ranch during 2010 before turbine erection. However, we found evidence that pronghorn avoided wind turbines in winters after development within their winter home ranges. This relationship was most evident during winter 2011, which coincided with the most severe winter of our study. Long-term replicated studies will be necessary to make inferences for pronghorn populations exposed to wind energy development in different environments and scales than we evaluated. Nonetheless, in the absence of additional information on how ungulates respond to wind energy development, our finding that pronghorn avoided wind turbines within their winter home ranges has important implications for future wind development projects, particularly in areas known to fulfill important seasonal requirements of pronghorn populations.     

Louse- and flea-borne rickettsioses: biological and genomic analyses

In contrast to 15 or more validated and/or proposed tick-borne spotted fever group species, only three named medically important rickettsial species are associated with insects. These insect-borne rickettsiae are comprised of two highly pathogenic species, Rickettsia prowazekii (the agent of epidemic typhus) and R. typhi (the agent of murine typhus), as well as R. felis, a species with unconfirmed pathogenicity. Rickettsial association with obligate hematophagous insects such as the human body louse (R. prowazekii transmitted by Pediculus h. humanus) and several flea species (R. typhi and R. felis, as well as R. prowazekii in sylvatic form) provides rickettsiae the potential for further multiplications, longer transmission cycles and rapid spread among susceptible human populations. Both human body lice and fleas are intermittent feeders capable of multiple blood meals per generation, facilitating the efficient transmission of rickettsiae to several disparate hosts within urban/rural ecosystems. While taking into consideration the existing knowledge of rickettsial biology and genomic attributes, we have analyzed and summarized the interacting features that are unique to both the rickettsiae and their vector fleas and lice. Furthermore, factors that underlie rickettsial changing ecology, where native mammalian populations are involved in the maintenance of rickettsial cycle and transmission, are discussed.     

No Serologic Evidence for Zoonotic Canine Respiratory Coronavirus Infections among Immunocompetent Adults

Zoonotic diseases continue to emerge and threaten both human and animal health. Overcrowded shelters and breeding kennels create the perfect environment for amplified infectious disease transmission among dogs and present a critical opportunity for zoonotic pathogens to emerge and infect people who work in close contact with dogs. Coronaviruses’ widespread prevalence, extensive host range, various disease manifestations and increased frequency of recombination events all underline their potential for interspecies transmission (Methods Mol. Biol. 2008, 454, 43). The objectives of this study were to determine whether people with occupational contact with dogs were more likely to have antibodies against canine respiratory coronavirus (CRCoV) compared to persons with no dog exposure. A seroepidemiological cohort study was completed, for which 302 canine‐exposed and 99 non‐canine‐exposed study subjects enrolled in the study by providing a serum sample and completing a self‐administered questionnaire. A competitive enzyme‐linked immunosorbent assay (ELISA) was developed to detect human antibodies against CRCoV while controlling for cross‐reacting antibodies against the human coronavirus OC43. All study subjects were negative for antibodies against CRCoV by this competitive ELISA. This study supports the premise that humans are not at risk for CRCoV infections; however, infrequent cross‐species transmission of CRCoV cannot be ruled out.     

Antibodies to bovine parvovirus acquired by neonatal pigs through ingestion of virus and antibody in the diet

The ability of pigs to respond immunologically to ingestion of bovine parvovirus (BPV) was tested by feeding 4 cesarean-derived, colostrum-deprived (CDCD) pigs a live virus-contaminated, liquid diet for the first 4 weeks of life. Virus-neutralizing (VN) antibodies were detected in the serum of 2 of the 4 pigs when they were 4 weeks old. Antibody titer remained at about the same level for several weeks, then decreased during the remainder of the 29-week interval of testing. The relative reactivity of these sera based on results of indirect immunofluorescence paralleled the corresponding VN titer. Neither of the other 2 pigs exposed to BPV had any appreciable immune response. The potential for passive acquisition of antibody from the diet was tested by feeding 4 other CDCD pigs bovine colostrum containing antibodies to BPV and bovine viral diarrhea virus (BVDV) for the first 2 days of life. All had serum VN antibodies for both viruses when they were tested at 2 days of age. The decay rate of the heterologous, passively acquired antibody was approximately linear; however, antibody half-life was relatively short, about 3.5 days, and titers were no longer detectable when pigs were 4 weeks (BPV) and 6 weeks (BVDV) old. An additional 4 CDCD pigs fed a liquid diet without virus or antibody remained free of any appreciable serum reactivity for either BPV or BVDV. Results supported the hypothesis that antibodies for BPV previously detected in the serum of pigs and people may reflect ingestion of virus-contaminated bovine milk or milk products.     

Acetone-treated agglutinin against Yersinia pseudotuberculosis in free-living rats

Retrospective investigation was done on Yersinia pseudotuberculosis infection in barn rat populations living in an Yersinia endemic area and in zoo rat populations living in a nonendemic area. The OH agglutinins against Y pseudotuberculosis were normally distributed within both populations. Most of the OH agglutinin titers and many O agglutinin titers were reduced by treatment of sera with acetone. Sera with O and OH agglutinin titers were assigned to 2 groups, one with a titer less than 1:8 and the other with a titer of greater than or equal to 1:8. Rats harboring the organism did not possess O or OH agglutinin titers greater than 1:8 in acetone-treated sera. In most nontreated sera, OH agglutinin titers were higher than were the O agglutinin titers. However, in most acetone-treated sera, O agglutinin titers were equivalent to OH agglutinin titers. Differences by region and age were observed in acetone-treated O agglutinin titers of greater than or equal to 1:8 against Y pseudotuberculosis. Therefore, it is recommended that to detect antibody against Y pseudotuberculosis in rats, sera should be treated with acetone before the test and O antigen should be used.     

Seroprevalence of five arboviruses in sentinel cattle as part of nationwide surveillance in South Korea, 2009?2012

To investigate the possible circulation of arboviruses in South Korea, nationwide surveillance of five arbovirues was conducted in sentinel calves during 2009−2012. We used serum neutralization tests to investigate the presence of antibodies for the Aino virus, Akabane virus, bovine ephemeral fever virus, Chuzan virus and Ibaraki virus. In 2009, 2011 and 2012, the seropositive rates for these five arboviruses were all less than 14.1%. In 2010, however, the seropositive rates for Aino virus and Akabane virus were 33.2% and 40.2%, respectively. High seropositive rates were also associated with a large-scale outbreak of Akabane viral encephalomyelitis in cattle in southern Korea in 2010. Continued seroprevalence surveillance will be useful for monitoring natural arboviral diseases.     

Antibodies to Borrelia spirochetes in sera from Swedish cattle and sheep

In the southern parts of Sweden a Borrelia infection transmitted by the tick Ixodes ricinus may affect man, In the present study antibodies to Borrelia spirochetes were studied in sera from 58 cows, 68 calves and 13 lambs from areas in southern Sweden where Ixodes ricinus occurs. For comparison, serologic studies were also performed on 88 cows and 10 lambs from the northern parts of Sweden.Serum titers of > 80 were found in 14 of the calves and 23 of the cows from southern Sweden but in only 1 of the cows from northern Sweden. In 11 of the lambs from the south a serum titer of > 40 developed. None of the lambs from the north had a serum titer of > 40. The results indicate that cattle and sheep in certain areas of Sweden are exposed to Ixodes ricinus-borne Borrelia spirochetes.In 9 of the lambs from southern Sweden: an endemically occurring arthritis had developed. The possibility that this arthritis may be caused by Borrelia spirochetes is discussed.     

Pitfalls in immunofluorescence testing in canine dermatology

Indirect immunofluorescence testing for pemphigus-like antibodies was performed on 100 dogs: 50 dogs with various nonpemphigus dermatologic diseases, 25 dogs with various nondermatologic diseases, and 25 normal dogs. One dog (generalized demodicosis) was positive for pemphigus-like antibodies at a titer of 1:10. It was concluded that canine pemphigus-like antibodies are a potential source of misinterpretation and misdiagnosis in indirect immunofluorescence testing. Direct immunofluorescence testing for IgG, IgA, IgM, and C3 was performed on the footpads of 11 normal dogs. Granular deposition of IgM at the basement membrane zone was demonstrated in 5 of the 11 dogs. It was concluded that direct immunofluorescence testing of canine footpads using only polyvalent immunoglobulin antisera or anti-IgM antisera may lead to misinterpretation and misdiagnosis in up to 45% of all dogs tested.     

Serological relationships among subgroups in bovine viral diarrhea virus genotype 1 (BVDV-1)

Bovine viral diarrhea virus (BVDV) has various economic impacts associated with diarrhea, poor performance, an increase in the frequency of other infections and lethal outcomes. Both genotypes, namely BVDV-1 and BVDV-2, as well as different subgroups within these genotypes have been reported worldwide. Understanding the serological differences among the BVDV subgroups is important for disease epidemiology and prevention as well as vaccination programs. The aim of this study was to determine the serological relatedness among the subgroups in BVDV-1. For that purpose, sheep hyperimmune sera were collected against representative strains from 6 of the subgroups of BVDV-1 (BVDV-1a, -1b, -1d, -1f, -1h and -1l). The serum samples that gave the peak antibody titer to the homologous strains were used to perform cross neutralization assays. The highest homologous antibody titer (1:5160) was obtained against BVDV-1h. Regarding the cross neutralizing (heterologous) antibodies, the lowest titer (1:20) was produced by the BVDV-1f antiserum against the BVDV-1a and BVDV1-b viruses. The highest cross neutralizing titer (1:2580) achieved by the BVDV-1h antiserum was against the BVDV-1b strain. The cross neutralization results indicated particular serological differences between the recently described subgroup (BVDV-1l) and BVDV-1a/-1b, which are widely used in commercial vaccines. Considering the cross neutralization titers, it is concluded that selected BVDV-1l and BVDV-1h strains can be used for the development of diagnostic and control tools.