Avian hosts of St. Louis encephalitis virus in Pine Bluff, Arkansas, 1991

An investigation of the extent of St. Louis encephalitis (SLE) virus activity in the avian population in Pine Bluff, Arkansas was conducted from August 30, 1991 through September 5, 1991, following an SLE epidemic that resulted in 25 human cases. A total of 363 birds of 33 species were captured with ground-level mist nets at four sites along the northern edge of the city. No viruses were isolated from the serum of these birds, but 91 birds (25%) of 11 species had detectable neutralizing antibody against the TBH-28 strain of SLE virus in the constant-virus, serum-dilution, plaque-reduction neutralization test in Vero cell culture. No antibody to eastern equine encephalitis virus was detected. The prevalence of antibody to SLE virus varied among the sites from 11% to 44%, but the prevalence at each site was influenced by the avian species composition. The two most abundant species captured in the city, the American robin (43%) and house sparrow (42%), also had the highest prevalence of antibody. Nine other bird species were serologically positive but at significantly lower rates than for the abundant species. The antibody prevalence was higher in immature birds (27%) than in adult birds (15%), but the antibody titers were higher in adult birds than in immature ones. The overall SLE antibody prevalence and the prevalence for house sparrows were significantly higher than the average prevalence for avian hosts studied during previous SLE epidemics. Therefore, house sparrows would be a good choice for a local sentinel species.

Serologic analysis of white-tailed deer sera for antibodies to Borrelia burgdorferi by enzyme-linked immunosorbent assay and western immunoblotting

White-tailed deer serum samples were collected in the Minneapolis-St. Paul, Minn., metropolitan area during the fall and winter months from 1989 to 1992 and analyzed for antibodies to Borrelia burgdorferi, the etiologic agent of Lyme borreliosis. Ninety-eight percent of the serum samples were collected from regions where currently the vector tick, Ixodes dammini, is nonexistent. Antibodies to B. burgdorferi were detected in 2.2% of 508 samples by enzyme-linked immunosorbent assay, and their presence was confirmed by Western immunoblot analysis. Western immunoblotting yielded mean numbers of reactive bands of 0.1 and 6.0 for samples that were negative and positive for antibodies by enzyme-linked immunosorbent assay, respectively. The molecular weights of the antigens in many of the reactive bands from positive samples were similar to the molecular weights of antigens reactive with samples from humans with Lyme borreliosis. An antibody response to the major outer surface proteins A and B was not detected. Serologic analysis of deer sera may provide a valuable method for surveillance programs designed to monitor the spread of B. burgdorferi in nature.

Ecology of porcupines (Erethizon dorsatum) and Colorado tick fever virus in Rocky Mountain National Park, 1975-1977

The involvement of porcupines, Erethizon dorsatum (L.), in the ecology of Colorado tick fever (CTF) virus in Rocky Mountain National Park was investigated from 1975 to 1977. Porcupine dens and feeding activity were found mostly on rocky knolls or on south-facing slopes within open stands of the montane coniferous forest, and 20 adult porcupines were trapped or captured by hand at those locations. An average of 24.6 +/- 5.4 adult Dermacentor andersoni Stiles ticks were found per animal (annual range, 17.5-31.4 ticks). The minimum CTF virus infection rate of the ticks removed from porcupines varied from 129 to 257, whereas for questing adult D. andersoni ticks from the same geographic area was 205 in 1976. No virus was isolated from the 20 animals, but 85% had neutralizing antibody against CTF virus. Porcupines utilize the same habitats described for the CTF ecosystem in Rocky Mountain National Park and appear to be an important host for adult D. andersoni.

Susceptibility parameters of Aedes albopictus to per oral infection with eastern equine encephalitis virus

Aedes albopictus (Skuse) mosquitoes were fed on snowy egrets, Egretta thula (Thayer and Bangs), that had been infected by subcutaneous inoculation of eastern equine encephalitis (EEE) virus. Freshly fed mosquitoes were frozen and tested to determine how much virus they had ingested. Other fed mosquitoes from the same lots were incubated for 7 d at 27 degrees C before testing. Seven lots of Ae. albopictus fed on viremic birds. Based on average amounts of virus ingested and day 7 virus infection rates in mosquitoes from the same lots, the amount of virus required to infect 50% of the mosquitoes was calculated to be 10(2.8) Vero cell plaque-forming units (PFU). The infection threshold (i.e., the amount of virus required to infect from 1 to 5% of mosquitoes) was determined to be < or = 10 PFU per blood meal. These parameters indicate that Ae. albopictus is sufficiently susceptible to infection with EEE virus to enable it to acquire infectious doses from a wide variety of viremic birds and possibly from equines.

Oral colon transit scintigraphy using indium-111 DTPA: variability in healthy subjects

Oral colon transit scintigraphy using indium-111 diethylene-triamine-pentaacetic acid was performed in 41 healthy subjects (22 females, 19 males) to determine variability with age and sex and to define normal ranges. Repeat studies were performed in 10 females and 9 males to assess intra-subject variability. Females showed slightly but significantly slower colonic transit than men and slightly greater intra-subject variability. There was no correlation between age and colonic transit. The results have implications for the definition of normal ranges.

Experimental inoculation of three arboviruses in black-bellied whistling ducks (Dendrocygna autumnalis)

Wild-caught, immature black-bellied whistling ducks (Dendrocygna autumnalis) were inoculated with eastern equine encephalitis (EEE), St. Louis encephalitis (SLE), or western equine encephalitis (WEE) virus. Susceptibility, duration and titer of viremia, and antibody response to these arboviruses were determined. Birds from all inoculated groups became viremic. Higher virus titers occurred in the EEE group but overall mean titers were not significantly different among experimental groups. All birds inoculated with EEE and SLE viruses developed antibodies, and six of seven ducks receiving WEE virus were seropositive. All seropositive ducks had antibodies for at least 59 days, when the study was terminated. The EEE group had significantly more seropositive ducks during more days than the WEE and SLE groups. Geometric mean antibody titers were significantly smaller in the WEE group when compared to the EEE and SLE groups. Control ducks did not develop viremia or antibodies. Gross and histopathologic lesions compatible with viral encephalitis were absent in all of nine ducks necropsied. Black-bellied whistling ducks can develop low and short-term levels of viremia sufficient to infect mosquitoes, but probably cannot contribute significantly to the transmission of EEE and SLE. They may serve as good indicators of virus activity.

Serologic survey for selected arboviruses and other potential pathogens in wildlife from Mexico

During 1988 and 1989, a serologic survey of wildlife was conducted in northeastern Mexico to determine the presence, prevalence, and distribution of arboviruses and other selected disease agents. Eighty mammal specimens were tested. Antibodies to vesicular stomatitis-Indiana, Venezuelan equine encephalitis-Mena II, Rio Grande virus, and vesicular stomatitis-New Jersey were detected predominantly in small mammals. Deer and mouflon (Ovis musimon) had antibodies to bluetongue and epizootic hemorrhagic disease. Two species had serologic evidence of recent exposure to Francisella tularensis. A white-tailed deer (Odocoileus virginianus) had antibodies to Anaplasma marginale. All specimens tested for antibodies against Yersinia pestis and Brucella abortus were negative. Sera from 315 birds were tested for antibody against five equine encephalitis viruses and six avian pathogens. During 1988, antibodies to Venezuelan equine encephalitis-Mena II, Venezuelan equine encephalitis-TC83, St. Louis encephalitis, eastern equine encephalitis, and western equine encephalitis were detected in birds of several species. Antibodies to Pasteurella multocida and Newcastle disease virus were also detected. Birds from five species presented antibodies to Mycoplasma meleagridis. Specimens tested for M. gallisepticum, M. synoviae, and Chlamydia psittaci were negative. To the best of our knowledge, this survey represents the first serologic evidence of bluetongue, Cache Valley virus, epizootic hemorrhagic disease, Jamestown Canyon virus, vesicular stomatitis-Indiana, vesicular stomatitis-New Jersey, Rio Grande virus, and tularemia reported among wildlife in Mexico.

Borrelia burgdorferi infection in white-footed mice (Peromyscus leucopus) in hemlock (Tsuga canadensis) habitat in western Pennsylvania

White-footed mice (Peromyscus leucopus) were captured and their tissues sampled from 27 sites in seven counties of western Pennsylvania in 1990 for isolation and identification of Borrelia burgdorferi. Two hundred sixty mice were captured from which there were 27 isolations. Significantly more mice were captured and significantly more isolations made from hemlock (Tsuga canadensis) habitat than from deciduous species forest. Hemlock habitat is sparse and focal but evidently increases winter survival of mice, and thus possibly results in increased infection rates in mice.

Cloacal flora isolated from wild black-bellied whistling ducks (Dendrocygna autumnalis) in Laguna La Nacha, Mexico

Cloacal swabs from 110 adult black-bellied whistling ducks trapped at Laguna La Nacha, Tamaulipas, Mexico, were cultured to determine the prevalence of normal and potentially pathogenic bacteria. Twenty-five gram-negative enterobacteria and four gram-positive cocci were isolated. The most common isolates included Escherichia coli (54%), Staphylococcus spp. (29%), Streptococcus spp. (22%), Aeromonas hydrophila (15%) Enterobacter cloacae (14%), and Micrococcus sp. (14%). The implications of whistling ducks as possible reservoirs of pathogenic bacteria are discussed.

Comparison of oral iodine-131-cellulose and indium-111-DTPA as tracers for colon transit scintigraphy: analysis by colon activity profiles

In 11 normal subjects and 11 patients with a clinical diagnosis of constipation, oral 131I-cellulose and 111In-DTPA were compared simultaneously as tracers for radionuclide colon transit scintigraphy. Visual assessment of the images revealed no differences between tracers. Quantitation was performed using total and segmental percent retention and the derived value of clearance half-time. In addition, profiles of the activity distribution along the length of the colon were generated and the mean position of the activity in the colon calculated. For all indices, the results were similar in both normal subjects and constipated patients when comparing tracers, although marked differences were present between normal subjects and constipated patients for each tracer. Indium-111-DTPA was easy to administer and dosimetry was more acceptable than for 131I-cellulose, especially in constipated patients. It is concluded that 111In-DTPA is the preferred tracer for oral colon transit scintigraphy.

Isolation of Tete serogroup bunyaviruses from Ceratopogonidae collected in Colorado

Two viruses were isolated from ceratopogonid midges collected in northern Colorado. Electron microscopy indicated that both isolates were bunyavirus-like. Indirect fluorescent antibody and serum dilution-plaque reduction neutralization tests showed that these isolates were members of the Tete serogroup, most closely related antigenically to Tete and Batama viruses but distinguishable from both and from each other. We suggest the name Weldona virus for these isolates. Antibody in both waterfowl and passerine birds in northern Colorado indicates the enzootic presence of these viruses in northern Colorado and raises unanswered questions about the introduction and establishment of Tete serogroup viruses in the Americas.

Colon transit scintigraphy in health and constipation using oral iodine-131-cellulose

The purpose of the study was to assess if a new scintigraphic method for noninvasive assessment of colonic transit could differentiate between subjects with normal bowel transit and those with constipation. Eleven normal subjects and 29 constipated patients were given 4 MBq iodine-131-cellulose (131I-cellulose) orally and sequential abdominal scans were performed at 6, 24, 48, 72, and 96 hr from which total and segmental percent retentions were calculated. There were clear differences between the normal subjects and the constipated patients for the total percent retention at all time intervals, on a segmental basis in the right colon at 24 hr, and in all segments at 48 and 72 hr. Three-day urinary excretion of radioiodine was minimal; 2.4% +/- 1.2% (mean +/- s.d.) in constipated patients and 3.1% +/- 0.8% in normals, with approximately 75% occurring in the first day. The use of oral radiotracers in the investigation of constipation appears promising.

Western equine encephalitis in avian populations in North Dakota, 1975

The involvement of wild birds in western equine encephalitis (WEE) and St. Louis encephalitis (SLE) virus activity in the Red River valley area of North Dakota (USA) during a WEE epidemic was investigated in August 1975. Free-ranging birds were captured with mist nets and nestlings by hand. Virologic and serologic results indicated that a similar rate of WEE virus activity occurred throughout Richland County and between permanent and summer resident birds. The rate of SLE virus activity in the birds of Richland County was lower than for WEE virus, but the SLE antibody prevalence was greater in rural areas than within urban locations. Seven of the nine WEE virus isolations were from nestling birds of four different species; the remaining two from adults of two different species. Overall prevalence of neutralizing (N) antibody against WEE virus was 5% in nestling and 14% in adult birds but was the opposite for N antibody against SLE virus, 17% in nestling and 5% in adult birds. Differences between the two viruses in the presence and persistence of maternal N antibody or differential mortality in nestling birds may have caused the disparity in antibody prevalences.

Characterization of five new phleboviruses recently isolated from sand flies in tropical America

Five new phlebotomus fever virus serotypes (Bunyaviridae: Phlebovirus) are described. These viruses, designated Ambe, Ixcanal, Mariquita, Armero, and Durania, were isolated from sand flies (Diptera: Psychodidae) collected in Brazil, Colombia, and Guatemala. Two of the agents were recovered from pools of male sand flies. The new viruses are antigenically related to other members of the phlebotomus fever serogroup by immunofluorescence, but are distinct from the other 39 members of this serogroup by plaque reduction neutralization test.

Co-circulation of multiple Colorado tick fever virus genotypes

Colorado tick fever (CTF) virus, family Reoviridae, genus Orbivirus, contains 12 genes distinguishable by polyacrylamide gel electrophoresis (PAGE). Multiple genotypes of CTF virus were isolated at 3 field sites in Colorado in 1985. Five genotypes were found at Campos Cabin, 2 at Drake, and 6 at Rocky Mountain National Park. Virus isolations were made in 1985 from 6 patients with CTF. These isolates were distinct from each other and the field isolates. Although the CTF isolates were different by PAGE profile, the majority of the 12 genes were highly conserved among the 1985 isolates and a Florio isolate (FMA). Only genes 4 and 6 were variant among the 1985 CTF isolates and FMA, and no unique genes were identified. In 1986, a follow-up field survey was done at the Campos Cabin site. Of the 3 CTF PAGE genotypes obtained, 2 exhibited PAGE profiles which were different from the 1985 isolates. One isolate may have resulted from the reassortment of genes from 2 of the isolates circulating at Campos Cabin in 1985.

The ecology of Colorado tick fever in Rocky Mountain National Park in 1974. III. Habitats supporting the virus

Ecologic studies of small mammals in Rocky Mountain National Park (RMNP) were conducted in 1974 in order to identify the specific habitats within the Lower Montane Forest that support Colorado tick fever (CTF) virus. Data was collected on the abundance and distribution of 4 primary rodent species, tick infestation, CTF virus, and neutralizing antibody prevalence. Rodents were captured along transects crossing different habitats. Open stands of ponderosa pine and shrubs on dry, rocky surfaces were found to be important for maintaining CTF virus.

A plague epizootic in the white-tailed prairie dogs (Cynomys leucurus) of Meeteetse, Wyoming

Surveillance for sylvatic plague (Yersinia pestis) was conducted near Meeteetse, Wyoming (USA) from 24 May to 14 June 1985. Ten species of fleas were collected from white-tailed prairie dogs (Cynomys leucurus), and from their burrows and associated rodents. Five of these flea species and two adult prairie dogs were positive for plague. The progression of this plague epizootic appeared to be slower and the intensity was less than in previous epizootics in other prairie dog colonies. The plague epizootic occurred within the only known colony of black-footed ferrets (Mustela nigripes) and was a potential threat to the food source of this endangered species.

Isolation of Cache Valley virus and detection of antibody for selected arboviruses in Michigan horses in 1980

Blood samples collected in September and November 1980 from 87 horses in southwestern Michigan were examined for virus isolation and for plaque-reduction neutralizing antibody against selected arboviruses. Cache Valley virus was isolated from the blood of a clinically normal horse in St Joseph County in September. The age-specific antibody prevalence for Cache Valley virus indicated enzootic transmission in the study area. The high antibody prevalence and the lack of age-specific antibody prevalence indicated sporadic, but intense, exposure to Jamestown Canyon virus. Low prevalences of antibody were detected for Highlands J, snowshoe hare, St Louis encephalitis, and trivittatus viruses.

Epizootic vesicular stomatitis in Colorado, 1982: some observations on the possible role of wildlife populations in an enzootic maintenance cycle

Sera obtained from wild ungulates, carnivores, and rodents in Colorado were tested for neutralizing (N) antibody against vesicular stomatitis, New Jersey serotype (VSNJ), virus to determine their involvement in the 1982 Colorado VSNJ epizootic in domestic animals. Viremic and N antibody responses of two local rodent species to a 1982 Colorado isolate of VSNJ were determined in the laboratory. The rodents produced only weak viremias, but all developed N antibody. N antibody prevalences for VSNJ in sera from wild ungulates was sufficiently high to indicate their involvement during the epizootic. In addition, the demonstration of N antibody in elk (Cervus elaphus) and mule deer (Odocoileus hemionus) prior to the epizootic in cattle and horses suggests that an enzootic cycle may exist in Colorado.

Viremic enhancement due to transovarially acquired antibodies to St. Louis encephalitis virus in birds

Adult house sparrows (Passer domesticus) were captured and experimentally inoculated with St. Louis encephalitis (SLE) virus to produce high concentrations of circulating antiviral antibody. Nestlings, 5-7 and 14-16 days of age, from SLE immune adult females and challenged with SLE virus, exhibited viremic enhancement by producing viremias of greater duration and magnitude than did controls. Nestlings possessing maternal antibody and challenged with SLE virus between 8 and 13 days of age did not produce viremias differing significantly from controls in magnitude, duration, or temporal appearance. Experimental nestling sparrows possessed detectable amounts of maternally derived passive antibody to SLE virus prior to challenge with this virus. Passive geometric mean antibody titers ranged from a high of 1:34.5 in nestlings tested 5-7 days posthatching, to a low of 1:11.2 in 14-16-day-old birds. Results presented imply that enhancement of SLE virus infections could lead to increased viral amplification and dissemination rates during natural disease cycles.

Prognostic value of axillary lymphoscintigraphy in breast carcinoma patients

Axillary lymphoscintigraphy (AxLS) with bilateral interdigital injection of [99mTc]antimony sulfide colloid carried out concurrently with internal mammary lymphoscintigraphy in 488 patients with breast carcinoma was evaluated. Patterns of radiocolloid distribution within the ipsilateral axilla and supraclavicular fossa were compared with similar features on the contralateral side to determine whether image characteristics are significantly disrupted by prior surgery, reflect the presence of metastases, and can predict treatment failure. Interpretive criteria for AxLS were refined after correlation of the identified image components with clinical parameters including axillary surgery, lymph node histology and relapse within a follow-up period of 2 years from the study. Results indicate that AxLS is at least as accurate as clinical assessment and provides data predictive of relapse to complement axillary lymph node status although the technique cannot presently replace lymph node sampling for patient staging.

Distribution of Bunyamwera serogroup viruses in North America, 1956-1984

We attempted to tabulate all Bunyamwera serogroup (family Bunyaviridae, genus Bunyavirus) isolates from North America. By summarizing information from the laboratories of the Centers for Disease Control, data generously shared by other laboratories, and the published literature, we were able to accumulate data regarding 1,372 Bunyamwera serogroup viruses. These were: Tensaw (664, including 8 from vertebrates), Cache Valley (396, including 6 from vertebrates), Main Drain (160, including 14 from vertebrates), Lokern (69, including 8 from vertebrates), Northway (13, including 5 from vertebrates), Tlacotalpan (7), Santa Rosa (2), Santa Cruz (1 from a horse), and 60 of undetermined serotype. Virus isolation rates by month of collection were correlated with collection efforts, but associations of viruses and arthropod vectors varied by location, vertebrate host, and arthropod distribution. Tensaw virus was isolated principally from Anopheles crucians mosquitoes (466/656 isolates from arthropods) in the southeastern United States; Cache Valley virus principally from An. quadrimaculatus (94), Coquillettidia perturbans (59), Culiseta inornata (45), Aedes sollicitans (30), Psorophora columbiae (23), An. punctipennis (18), and Ae. vexans and trivittatus (18 each) mosquitoes (total = 305/382 isolates from arthropods from all of the United States and Canada, except the southeastern United States); Main Drain virus from Culicoides variipennis (31), Culicoides (Selfia) sp. (65), and Psorophora (23) and Aedes (21) species mosquitoes in the western United States; Lokern virus from Culicoides species (55/61 isolates from arthropods) in the western United States. Relationships between vector and vertebrate host distributions are discussed briefly in regard to geographic distribution of the Bunyamwera serogroup viruses.

Late cardiac, thyroid, and pulmonary sequelae of mantle radiotherapy for Hodgkin's disease

Cardiac, thyroid and pulmonary function were evaluated in 25 patients aged 35 years or under, treated for Hodgkin's disease by mantle radiotherapy 5-16 years previously. No patient had symptoms of heart disease. Although thallium myocardial perfusion scintigraphy was normal in all patients, abnormalities of myocardial function were detected in 6 (24%) patients using gated equilibrium rest and exercise radionuclide ventriculography. Resting left ventricular ejection fraction (LVEF) was abnormal in 1 patient, and in 3 patients there was an abnormal LVEF response to exercise. All 6 patients had right ventricular dilatation. Apical hypokinesia was present in 4 of these patients. A small asymptomatic pericardial effusion was detected by M-Mode echocardiography in only 2 (8%) patients. Twenty-three (92%) patients had evidence of abnormal thyroid function. Two (8%) patients had become clinically hypothyroid. Serum TSH was elevated in 13 (52%) patients and TRH stimulation test was abnormal in a further 10 (40%) patients in whom TSH was normal. Pulmonary function studies showed a moderate decrease in diffusing capacity (72% of predicted) and a minor reduction in lung volume. Although a high incidence of cardiac, thyroid and pulmonary abnormalities was detected, only the 2 patients who had become hypothyroid were symptomatic. Modification of the irradiation technique may reduce the incidence of cardiac abnormalities, but is unlikely to alter significantly the thyroid or pulmonary sequelae.