Inpatient and outpatient health care demand in Cairo, Egypt.

This paper uses the results of a household survey conducted in Cairo, Egypt in 1992 to examine the factors that influence the demand for inpatient and outpatient health services. Multi-stage discrete choice models of the demand for health care, which identify the importance of individual, household, and facility level variables on each treatment decision, are estimated separately for outpatients and inpatients. Consumers are assumed to decide whether to seek any treatment and then choose between three categories of providers: a large public hospital (Embaba Hospital), all other public providers, and private/charitable providers. The results confirm that more affluent consumers prefer the higher cost, higher quality private and charitable hospitals. Age, sex, education, and insurance are also found to strongly impact the use of medical services. The results are suggestive but do not conclusively show that inpatient care is less price responsive than outpatient care. Price responsiveness of inpatient and outpatient demand are imprecisely estimated because price is highly correlated with quality, and the available data on facility quality do not permit us to adequately control for quality variations across facilities.

Vaccines against coxiellosis and Q fever. Development of a chloroform:methanol residue subunit of phase I Coxiella burnetti for the immunization of animals.

We have demonstrated the safety, immunogenicity, and efficacy of the WC and CMR vaccines in guinea pigs. Vaccination of guinea pigs with either WC or CMR protects animals against challenge with virulent C. burnetii. A total of 2 micrograms of either WC or CMR vaccine was a significant priming dose. A total of 20 micrograms gave complete protection against lethal challenge. Detection of antibodies to phase II cells by microaglutination, after vaccination with either WC or CMR and before lethal challenge, correlated with the ability of guinea pigs to mount a protective immune response. The PD50 values for WC and CMR vaccines, administered as a single dose, were 0.3 and 1.4 micrograms per animal, respectively. In contrast, the PD50 values for the WC and CMR vaccines, administered as two doses, were 0.83 and 0.72 micrograms per animal, respectively. Although the PD50 values for the two vaccines are similar, the CMR vaccine is preferred over the WC vaccine because it induces significantly fewer adverse reactions, and repeat injections can be given. Unvaccinated guinea pigs do not clear infectious microorganisms after challenge infection. Vaccination before challenge infection reduces the infectious load of C. burnetti in the blood and in various organs of the animals. When vaccinated animals were challenge infected and treated with rifampicin, the microorganisms were not eliminated from various organs. However, the combination of vaccination, challenge, and rifampicin treatment is effective in reducing the number of infectious microorganisms in some of these sites. We have demonstrated the safety and immunogenicity of the CMR vaccine in sheep and goats. Animals that were seropositive for one or more antigens developed significant levels of antibodies to alternate antigens, but no adverse reactions were observed at the site of s.c. injection of the CMR vaccine. This demonstrates that seropositive animals can be successfully immunized with this vaccine. These results also indicate that a long-term vaccination program using the CMR vaccine has the potential for producing animals with significant antibody titers to C. burnetii and perhaps lifelong immunity. The goal of a Q fever vaccination program is to produce immunized animals that are able to clear completely the infectious microorganisms. The appropriate vaccination schedule to render adult animals and their offspring "Q fever-free" should now be thoroughly investigated.

Efficacy of a commercial bacterin in protecting strain 13 guineapigs against Bordetella bronchiseptica pneumonia.

Bordetella bronchiseptica is known to be endemic in many guineapig (Cavia porcellus) colonies, and periodically is the aetiological agent of fatal epizootics of bronchopneumonia. A commercial, non-adjuvant B. bronchiseptica bacterin, which is approved for use in canines, was evaluated for induction of a protective immune response in Strain 13/N guineapigs against an airborne challenge of virulent B. bronchispeptica in small-particle aerosol. Seronegative animals were vaccinated on days 0 and 21 with intramuscular injections of 0.2 ml of bacterin. Humoral antibody titres of the vaccinated animals, as determined by ELISA, ranged from 128-1024 on day 49. On day 30 following the second dose of bacterin (study day 51), 12 vaccinated and 12 PBS sham-vaccinated animals were exposed to an inhaled dose of 4.3 x 10(5) CFU of B. bronchiseptica (325 LD50). Vaccinated, challenged animals remained clinically normal, although each guineapig did develop a localized upper respiratory infection. The rate of weight gain as well as rectal temperature of these animals were analogous to those exhibited by the control groups. Examination of 4 of the vaccinated, challenged animals on day 7 after exposure showed bacteria present in moderate to high numbers in the larynx and trachea but only minimally detectable in the lungs; by 30 days after exposure, the numbers of bacteria in the larynx and trachea were diminished, with none being detected in the lungs. Pathological alterations induced by B. bronchiseptica were not detected at either day 7 or day 30 after challenge in any of the vaccinated, challenged animals. Protection induced in Strain 13/N guineapigs by the commercial canine bacterin was sufficient to preclude the development of pulmonary disease, even in animals presented with a massive challenge of virulent bacteria in a small-particle aerosol.

Aerosol transmission of Hantaan and related viruses to laboratory rats.

Hantaan, Seoul, and Puumala viruses were transmitted to 12-16-week-old female Wistar Rattus norvegicus by inhalation. The rodent infectious dose for each virus by intramuscular inoculation and by inhalation was determined, as was the infectious dose for Vero E-6 cells by direct plaque assay.

Nose-only versus whole-body aerosol exposure for induction of upper respiratory infections of laboratory mice.

The effectiveness of two aerosol delivery systems, nose-only and whole-body, were compared using Swiss-Webster mice and two pathogens, Klebsiella pneumoniae and Venezuelan equine encephalitis (VEE) virus. With K. pneumoniae the median lethal dose (LD50) and the mean time to death correlated with the inhaled dose. An LD50 value of 335 colony forming units (cfu) for nose-only exposure was significantly less than the LD50 value of 3741 cfu obtained for whole-body exposure. The LD50 values obtained with VEE virus for nose-only exposure [8 plaque forming units (pfu)] and whole-body exposure (11 pfu) were similar to each other. Following a 10-min nose-only exposure, concentrations of K. pneumoniae approximating 10(4)/g were present after 24 hr in the upper respiratory tract (URT) and lungs. The numbers of bacteria reached a peak at 72 hr, when resolution of the infection began. Detectable levels of bacteria in the blood and tissues were delayed in mice given whole-body exposure, plus there was a decreased concentration of bacteria per gram of tissue. Major pathological lesions induced by K. pneumoniae were mild suppurative rhinitis and minimal suppurative bronchopneumonia. Viremia was greatest at 96 hr following aerosol exposure to VEE. Virus concentrations in the URT, lungs, cerebrum, spleen and mesenteric lymph nodes reached maximum titers earlier for mice exposed by nose-only than for mice exposed to whole-body aerosols.(ABSTRACT TRUNCATED AT 250 WORDS)

Airborne-induced experimental Bordetella bronchiseptica pneumonia in strain 13 guineapigs.

To evaluate the efficacy of a commercial bacterial vaccine in protecting Strain 13 guineapigs against fatal Bordetella bronchiseptica pneumonia, it was necessary to establish the infectivity and disease pathogenesis induced by virulent organisms. When guineapigs were exposed to small-particle aerosols of varying concentrations of virulent B. bronchiseptica, a spectrum of disease was produced that ranged from inapparent illness to fulminant bronchopneumonia. Clinical signs began by day 4 after exposure, and were evidenced by anorexia, weight loss, respiratory distress and serous to purulent nasal discharge. Pathological alterations were limited to the respiratory system. Moribund animals exhibited a suppurative necrotizing bronchopneumonia and necrotizing tracheitis. In animals that survived the challenge, the bacteria were eliminated from the lungs by day 28 but continued to persist in the laryngeal area and the trachea. The median infectious dose and the median lethal dose were estimated to be 4 colony-forming units (CFU) and 1314 CFU respectively. These data suggest that the guineapig will be a valuable model system in which to study interactions between Bordetella species and host cells as well as to evaluate potential B. bronchiseptica immunogens.

Animal models in Q fever: pathological responses of inbred mice to phase I Coxiella burnetii.

The susceptibility of inbred strains of mice to infection by phase I Coxiella burnetii, the aetiological agent of Q fever, was investigated by evaluating morbidity, mortality, antibody production and in vitro proliferative responses of splenic lymphocytes. Among the 47 strains of mice tested for morbidity and mortality to C. burnetii infection, 33 were resistant, 10 were of intermediate sensitivity, and four were sensitive. A/J mice exhibited the highest mortality, and surviving mice of this strain yielded high concentrations of viable rickettsiae from essentially all organs for more than 3 weeks after inoculation. However, A/J mice developed a protective immune response after vaccination with inactivated C. burnetii cells. Induction of gross pathological responses and antibody production were similar in sensitive mice (strain A/J) and resistant mice (strain C57BL/6J). The LD50 of phase I C. burnetii for A/J mice was about 1000-fold lower than that for the more resistant C57BL/6J mice. Mice of both strains developed antibody titres against phase I cells, phase II cells, and phase I lipopolysaccharide after the injection of one or more viable phase I organisms of C. burnetii; five or more rickettsiae caused splenomegaly that was almost proportional to the infecting dose. Suppression of in vitro proliferative responses of splenic lymphocytes to concanavalin A, a T-cell mitogen, was apparent after infection of sensitive A/J mice with as few as one to five phase I micro-organisms. However, suppression of proliferation of splenic lymphocytes from resistant C57BL/6J mice required 10(7) phase I C. burnetii.

Q fever vaccination of sheep: challenge of immunity in ewes.

Adult ewes (17 months of age) were vaccinated against Coxiella burnetii, using a formalin-inactivated whole cell (WC) phase I Henzerling strain vaccine or a chloroform methanol residue (CMR) vaccine. Nineteen pregnant ewes were placed in 3 categories [(i) unvaccinated, (ii) WC vaccine, and (iii) CMR vaccine] and were challenge exposed at approximately the 100th day of gestation with 210,000 plaque-forming units of C burnetii inoculated subcutaneously. Shedding of rickettsiae was measurably reduced, but was not prevented in vaccinated groups, as shown by inoculating ewes' placental tissues, amniotic fluid, and colostrum into mice, as well as by histopathologic lesions of placental tissues. The rickettsiae were shed in the placenta, amniotic fluid, or colostrum in 6 nonvaccinated ewes. In comparison, rickettsiae were detected in placental inoculations from 2 of 6 ewes in the WC vaccine group and 1 of 6 in the CMR group. In contrast to those in the vaccinated ewes, placentitis, high concentrations of rickettsiae in microscopic preparations, and weak lambs were typical for the nonvaccinated ewes.

A negative search for four infectious agents in inflammatory bowel disease.

Diseased resected portions of intestine from patients with inflammatory bowel disease were examined by chicken embryo inoculation for the presence of chlamydia and histologically for the presence of chlamydia, intracellular campylobacters, Tyzzer's bacilli, and cryptosporidia. Chlamydia were not isolated from any of the seven colon specimens tested and chlamydia, intracellular campylobacters, Tyzzer's bacilli, and cryptosporidia were not demonstrated in 39 sections of colon and ileum from 16 IBD patients.

Genetic heterogeneity among isolates of Coxiella burnetii.

Chromosomal and plasmid DNA have been extracted from six isolates of Coxiella burnetii, the aetiological agent of Q fever. Restriction fragment length polymorphisms detected after HaeIII digestions of chromosomal DNA revealed four different patterns that distinguished the American from the European isolates, and the Nine Mile phase I prototype strain from a spontaneously derived, isogenic phase II nonrevertant variant. At least one of the HaeIII fragments visible in the pattern from Nine Mile phase I and not in that from Nine Mile phase II could not be detected by DNA-DNA hybridization, and thus may have been deleted during the phase transition. Comparison of Nine Mile phase II, which does not survive animal passage, with Grita M44 phase II, which does, indicated that the HaeIII fragment was present in the Grita strain. These results suggest that this HaeIII fragment may be concerned with functions necessary to survive the cellular immune response in vivo. Isolates from two human endocarditis cases showed the greatest divergence from all the other isolates, having at least five fragments of unique mobility in the HaeIII digestion pattern of their chromosomal DNA. Also, a plasmid obtained from these two isolates was 2 to 3 kb larger than the plasmid present in the other five isolates, and its restriction pattern could be distinguished from that of the other plasmids by several endonucleases. Detection of chromosomal and plasmid restriction fragment length polymorphisms among strains of phase I or phase II C. burnetii from various geographical locations and environmental sources will facilitate Q fever diagnosis and strain identification.

Protective efficacies of live attenuated and formaldehyde-inactivated Venezuelan equine encephalitis virus vaccines against aerosol challenge in hamsters.

Although two investigational vaccines are used to immunize humans against Venezuelan equine encephalomyelitis virus, neither had previously been tested for protective efficacy against aerosol exposure. Live attenuated vaccine (TC-83) protected all hamsters challenged by either aerosol or subcutaneous routes with 4.7 to 5.2 log10 PFU of virulent Venezuelan equine encephalomyelitis virus. Formaldehyde-inactivated vaccine (C-84) failed to protect against aerosol challenge but did protect against subcutaneous challenge. Protection elicited by TC-83 vaccine did not depend solely on serum-neutralizing antibody. These studies suggest that TC-83 vaccine is preferable to C-84 vaccine for protecting laboratory workers at risk to aerosol exposure.

Effect of environmental factors on aerosol-induced Lassa virus infection.

Previous studies suggested that the most frequent means of transmission of Lassa virus was by either direct or indirect contact with infectious material. Aerosol stability and respiratory infectivity of the Josiah strain of Lassa virus were assessed to determine the effect of environmental factors on aerosol-induced infection. The stability of the virus in aerosol, particularly at low relative humidity (30% RH), plus the ability of the virus to infect guinea pigs and monkeys via the respiratory route emphasize the potential for aerosol transmission of Lassa virus. Biological half-lives at both 24 and 32 degrees C ranged from 10.1 to 54.6 min, and were sufficient for aerosol dispersion of virus to considerable distances in natural situations. Infectivity of Lassa virus in small particle aerosol was demonstrated in outbred guinea pigs and cynomolgus monkeys using dynamic aerosol equipment. Monkeys exposed to inhaled doses to 465 PFU were infected and died. The median infectious dose (ID50) for guinea pigs was 15 PFU, yet a definitive median lethal aerosol dose (LD50) could not be established. Organ tropism of aerosol-induced Lassa virus infections in outbred guinea pigs was similar to that previously reported for inbred guinea pigs infected by subcutaneous inoculation.

Rocky Mountain spotted fever in areas of high and low prevalence: survey for canine antibodies to spotted fever rickettsiae.

Antibodies to Rickettsia rickettsii were detected by indirect immunofluorescence in sera from 149 of 467 dogs (32%) examined from 4 military installations located in Kentucky, North Carolina, Pennsylvania, and Virginia. The prevalence at individual installations ranged from 4.3% at Fort Knox, Ky, to 63.4% at Fort Bragg, NC. Most of the seropositive dogs were in the working and sporting groups of dogs. The difference in antibody prevalence between sexes was not significant. Serologic responses were related to R rickettsii infection, although antibodies to R montana also were detected in a few of the sera. Comparison of serodiagnostic methods indicated that the indirect fluorescent antibody test was more sensitive than was the indirect hemagglutination test for obtaining survey data on the prevalence of Rocky Mountain spotted fever in the area.

Establishment of a canine cell line: derivation, characterization, and viral spectrum.

A cell line, designated A-72, for virus studies was established from a tumor surgically removed from a female, 8-year-old Golden Retriever dog. Following explant culture, the cells were serially passaged 135 times. The A-72 cells maintained a fibroblastic appearance and, at the 123rd passage, had a population doubling time of approximately 27 hours. Karyotypic analysis of the high passage cells showed the modal 2n chromosome number was 92 to 93. Using starch gel electrophoresis for enzyme characterization, the electrophoretic mobilities of enzymes extracted from A-72 cells were identical with those of canine peritoneal fibroblasts and primary canine kidney cells. The A-72 cells were susceptible to infection with infectious canine hepatitis virus, canine adenovirus type II, canine herpesvirus, canine parainfluenza virus, and canine coronavirus, but were not susceptible to canine distemper virus or the minute virus of canines. These cells have been particularly useful for studies of the fastidious canine coronaviruses, as the commonly used primary canine kidney cells exhibit varied susceptibility to these viruses.

Gamma-irradiated scrub typhus immunogens: analysis for residual, replicating rickettsiae.

Scrub typhus immunogens that received inadequate gamma radiation contained residual, viable rickettsiae. The presence of these organisms in the host was masked by the rapid immune response elicited by the large number of inactivated rickettsiae. Transfer of homogenized spleen cells from immunized mice to normal syngeneic recipients provided a sensitive technique for the detection of these viable, replicating organisms.

Cell-mediated and humoral immune responses of German Shepherd Dogs and Beagles to experimental infection with Ehrlichia canis.

The cell-mediated and the humoral immune responses of 12 German Shepherd Dogs and 5 Beagles inoculated with Ehrlichia canis were evaluated. Results indicated that specific and nonspecific immunosuppression due to E canis occurred in the German Shepherd Dogs. Canine leukocyte migration-inhibition factor was successfully isolated and shown to be physically and functionally similar to human and guinea pig migration inhibition factor. Of the German Shepherd Dogs, 58% developed positive cell-mediated responses; 80% of the Beagles became positive. German Shepherd Dogs that developed severe chronic ehrlichiosis did not respond to as great a degree as did the German Shepherd Dogs and Beagles with mild chronic disease. The cell-mediated responses decreased with time and disappeared by 147 days after inoculation. Humoral antibody titers in all inoculated dogs increased with time and remained at increased concentrations. Treatment of four inoculated dogs with antilymphocyte serum did not modify the course of the disease. The findings indicated that cell-mediated immunity may have a significant role in determining the course of disease in dogs infected with E canis.

Somatic cell hybrids of canine peritoneal macrophages and SV40-transformed human cells: derivation, characterization, and infection with Ehrlichia canis.

Somatic cell hybrids were obtained by fusion of canine peritoneal macrophages and SV40-transformed human skin fibroblasts. A cell line (WRH-2) was established from a single isolated hybrid clone. The WRH-2 cell line has been serially passaged 60 times and has a population doubling time of approximately 24 hours. Karyotypic analysis showed the modal number of chromosomes to be 80, with a selective segregation of canine chromosomes. Expression of incorporated canine DNA was substantiated by cellular enzyme activities and antigen expression. The susceptibility of 5% to 7% of WRH-2 cells to Ehrlichia canis infection was associated with phagocytic properties of these cells. Magnetic separation of phagocytic cells after ingestion of carbonyl iron resulted in a significant enhancement of the phagocytic population with a concomitant increase in the percentage of cells susceptible to ehrlichial infection. Serial passage of the selected subpopulation of hybird cells, however, resulted in a rapid diminution in the percentage of phagocytic cells.