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Biomedical subjects

A L Bourgeois

Publications and source records attributed to A L Bourgeois.

At least 55 records · Page 3Linked to original sources
PubMed1986

Evaluation of febrile patients in Port Sudan, Sudan: isolation of dengue virus.

One hundred consecutive patients admitted to the Port Sudan Hospital with a temperature greater than or equal to 100 degrees F were evaluated. Enteric fever was diagnosed in 19 patients and malaria in 13. Virologic studies identified 21 cases of dengue infection. One dengue 1 and 17 dengue 2 infections were diagnosed by viral isolation. Three untyped dengue infections were identified serologically. The clinical presentation and course of patients infected with dengue virus were most consistent with classic dengue fever. There was no evidence of hemorrhagic phenomena or shock in any of the dengue-infected patients. Both dengue 1 and 2 must be considered causes of acute fever in East Africa.

Adolescent↗
PubMed1982

Population indices of chiggers (Leptotrombidium deliense) and incidence of scrub typhus in Chinese military personnel, Pescadores Islands of Taiwan, 1976-77.

Larval Leptotrombidium deliense were recovered from live-trapped Suncus murinus, Rattus rattus and R. norvegicus captured in the Pescadores Islands of Taiwan during 1976 and 1977. Weekly and monthly indices of chigger infestation expressed as a percentage of hosts infested and the number of chiggers per host for S. murinus and Rattus spp. were calculated. Close correlations were observed between monthly indices of L. deliense measured for S. murinus and Rattus spp. and the number of laboratory-confirmed cases of scrub typhus per month. Weekly indices from S. murinus correlated more closely with number of cases than did weekly indices from Rattus spp. The critical level of chigger infestation necessary for a single case of scrub typhus in a month was estimated at 0.69 chigger per S. murinus and 0.68 chigger per Rattus spp. The weekly index of chigger infestation necessary for a single case of scrub typhus during a week was calculated at 0.47 chiggers per shrew. Critical levels of chigger infestations expressed as percentages of hosts infested were not calculated.

Animals↗
PubMed1981

Cell wall modification resulting from in vitro induction of L-phase variants of Nocardia asteroides.

The chemical composition of the cell walls of several L-form revertants derived from Nocardia asteroides 10905 was determined at different stages of growth. It was observed that each L-form revertant had a cell well that differed from that of the parental strain when grown under identical conditions. In some strains the peptidolipid and mycolic acid components were affected the most, whereas in other strains the fatty acid, sugar, and mycolic acid moieties were altered. Shifts in mycolic acid size were prominent, whereas the basic peptidoglycan structure appeared to be affected the least. Both the method used to induce the L-form of N. asteroides 10905 and the length of time these organisms were maintained in the wall-less state affected the degree of cell wall modification during the reversion process. Thus, removal of the cell wall appeared to potentiate and select for mutational alterations within the cell envelope of N. asteroides, and these changes resulted in altered cellular and colonial morphology.

Amino Acids↗
PubMed1980

In vitro stimulation of human peripheral blood lymphocytes by soluble and membrane fractions of renografin-purified typhus group rickettsiae.

Cell-free extracts of disrupted Renografin-purified Rickettsia typhi and R. prowazekii were evaluated as antigens in lymphocyte transformation assays for cell-mediated immunity to typhus group rickettsiae in 19 individuals with and 9 without histories of exposure to these organisms. Exposure consisted of clinical disease, vaccination with epidemic typhus vaccine, or occupational exposure to these agents. Both the soluble and membrane fractions of disrupted purified rickettsiae were used, and transformation of peripheral blood lymphocytes (PBL) was determined in microcultures by incorporation of [(3)]thymidine. Of the antigen concentrations tested (1 to 400 mug/ml), 10mug/ml appeared to be the most satisfactory. At this concentration, PBL transformation was highly reproducible and correlated well with donor exposure and the presence of enzyme-linked immunosorbent assay anti-typhus group immunoglobulin G. At higher concentrations, PBL from both exposed and control donors often responded to a lipopolysaccharide-like component present in these preparations. Specific transformation responses to rickettsial fractions were detected in several individuals decades after infection or vaccination, indicating that both fractions contained antigens associated with persisting cell-mediated immunity in humans. Generally, stimulation indexes with the soluble fraction were slightly greater than those obtained with corresponding concentrations of the membrane preparation, and in three individuals transformation was observed only with the soluble fraction. PBL transformation to soluble fractions also appeared to have some species specificity, since PBL from individuals with documented R. typhi infections were more responsive to the homologous soluble preparation than to the soluble fraction of R. prowazekii. PBL transformation also correlated well with homologous but only poorly with heterologous enzyme-linked immunosorbent assay immunoglobulin G titers.

Antibodies, Bacterial↗
PubMed1980

Identification of mosquito blood meals by cellulose acetate and starch gel electrophoresis.

Cellulose acetate (CAE) and starch gel electrophoresis (SGE) were examined for their ability to identify species hemoglobins in mosquito blood meals. Blood meals analyzed serologically by the precipitin (PT) and passive hemagglutination inhibition (PHI) techniques served as standards for comparison. CAE, could not differentiate blood meals from divergent vertebrate hosts (man, rabbits, and mice) solely on the basis of the migratory properties of their respective hemoglobins. However, all could be differentiated when the migratory properties of both their hemoglobins and serum albumins were considered. CAE, like PT, was consistently able to identify blood meals for 18--24 hr post-ingestion. In contrast, PHI was able to identify blood meals for up to 48 hr post-feeding. SGE lacked the sensitivity of CAE, PHI and PT. SGE could only differentiate blood meals for 5--7 hr after ingestion. These results indicate that CAE has potential as a rapid technique for determining the origin of blood meals ingested by arthropod disease vectors.

Aedes↗
PubMed1980

Prevention of scrub typhus. Prophylactic administration of doxycycline in a randomized double blind trial.

We conducted a prospective randomized double blind study on the effects of doxycycline as a prophylactic antibiotic against scrub typhus. A total of 1,125 military subjects was followed for periods as long as 5 months of exposure in a hyperendemic focus in the Pescadores Islands of Taiwan. Oral 200 mg doses of doxycycline (Vibramycin) or placebo were given once each week throughout the trial. The incidence rate of scrub typhus in the placebo group was 2.5 times greater than that of the group taking doxycycline (P = 0.11). When subjects who failed to comply with scheduled administration of doxycycline were removed from the analysis, the incidence rate of scrub typhus in the control group was five times greater than that in the drug group (P = 0.04). The rates of infection with Rickettsia tsutsugamushi and of sick call reports were the same in experimental and control groups. The drug was well tolerated in pretrial tests and complaints were negligible during the conduct of the trial. Doxycycline appears to be an excellent antibiotic for the prevention of scrub typhus among personnel exposed to high risk of infection with R. tsutsugamushi.

Dose-Response Relationship, Drug↗
PubMed1979

Changing risk of scrub typhus in relation to socioeconomic development in the Pescadores islands of Taiwan.

Long term changes in risk of Rickettsia tsutsugamushi infection among civilian residents of the Pescadores Islands of Taiwan were associated with changing social conditions. Age specific incidence rates of scrub typhus in the Pescadores before 1940 were highest among children under 5 years of age. Rickettsiae can be demonstrated in vectors, wild animals continue to be infected and scrub typhus occurs in military personnel. A serologic survey for antibody to R. tsutsugamushi was conducted during 1975 and 1977 and failed to show evidence of previous infection among children. Two events appear to be associated with the decreased incidence of rickettsial infection in the young: increased urbanization and increased enrollment in schools. Both changes accompanied socioeconomic development which took place in the islands during the past 50 years. Prevalence of antibody to R. tsutsugamushi continues to be equal in the sexes and is undoubtedly due to similar occupational exposure of both sexes in fields and farms where vectors are numerous. The absence of apparent morbidity due to scrub typhus among the civilian populace was attributed to the mild nature of the disease caused by Pescadores strains, misdiagnosis and a lack of obligatory reporting.

Adolescent↗
PubMed1979

Sensitive microplate enzyme-linked immunosorbent assay for detection of antibodies against the scrub typhus rickettsia, Rickettsia tsutsugamushi.

A microtiter enzyme-linked immunosorbent assay (ELISA) has been developed for the titration of antibodies against scrub typhus in human and animal sera. Scrub typhus rickettsiae were grown in monolayers of irradiated mouse LM3 cells and separated from host cell materials by differential centrifugation, filtration through a glass filter (AP-20, Millipore Corp.), and isopycnic banding in Renografin density gradients. The scrub typhus ELISA antigens were obtained from the purified viable rickettsiae by French pressure cell disruption and addition of 0.2% Formalin to the soluble extract. Antisera prepared in rabbits against the prototype Karp, the Kato, and the Gilliam strains of scrub typhus were used to standardize the ELISA and to compare its sensitivity and specificity to that of the indirect fluorescent antibody test (IFA). ELISA titers were measured as the greatest serum dilution showing an optical density 0.25 above controls or by the optical density achieved at a fixed serum dilution. The IFA and ELISA end point titers were quite similar, and all three measures of titer had comparable specificity for the strains of scrub typhus. No cross-reactions between the typhus and scrub typhus wera were observed by ELISA. Both the immunoglobulin M (IgM) and IgG antibody titers of 12 sequential sera from four patients with scrub typhus were obtained by IFA and ELISA. The IFA and ELISA end point titers for IgM and IgG had correlation coefficients of 0.91 and 0.97, respectively, whereas the ELISA optical density values at a serum dilution of 1:100 had slightly lower correlations with IFA titers (0.80 and 0.94). Early rising IgM titers followed by rising IgG titers were demonstrated by ELISA in three patients with primary scrub typhus infections, whereas the IgG response predominated in a patient with a reinfection. It is concluded that the ELISA for scrub typhus is a very satisfactory alternative to the IFA test.

Animals↗
PubMed1977

Antibodies against murine typhyus in sera from Indonesians.

A sero-epidemiological study of human CF and indirect immunofluorescence antibodies against murine typhus was conducted in Indonesia. Antibody prevalences ranged from 10% to 20% in sera of Indonesians from Java and Sumatra to less than 2% in sera from islands east of Java.

Antibodies, Bacterial↗
PubMed1977

Epidemiological and serological study of scrub typhus among Chinese military in the Pescadores islands of Taiwan.

An outbreak of 69 cases of scrub typhus occurred among Chinese military personnel stationed in the Pescadores Islands, Taiwan Province, Republic of China between May and November 1975. A retrospective epidemiological study of this outbreak indicated that military personnel over 40 were more likely to have scrub typhus than those under 40. High risk groups included the Garrison Force (home guard), anti-aircraft gunners and infantry and armoured units stationed at Hsing-jen. The onset of symptoms in 69% occurred within one year of residence in the Pescadores. The clinical course of scrub typhus and the serological response to infection were also studied. Eschar formation, fever, headache chills and lymph node enlargement were the predominant clinical manifestations noted. The indirect immunofluorescent antibody test (IFAT) demonstrated diagnostic (four-fold) rises in antibody titres to Rickettsia tsutsugamushi reference strains in 36 of 41 paired sera tested. 11 of 19 patients from whom only single sera were obtained had IFA titres presumptive of scrub typhus (greater than or equal to 1:160). Of 19 patients experiencing possible primary infections, 13 (68%) responded with antibodies directed against more than one reference strain of R. tsutsugamushi. These results suggest that several antigenically diverse strains of R. tsutsugamushi may be active in the Pescadores.

Animals↗
PubMed1977

Rickettsia tsutsugamushi infection and scrub typhus incidence among Chinese military personnel in the Pescadores Islands.

Personnel assigned to infantry units of the army of the Republic of China (Taiwan) stationed in the Pescadores Islands experienced the highest incidence rate of scrub typhus (4%) and the highest rate of Rickettsia tsutsugamushi infection (12%) of the units studied during 1976. The ratio of scrub typhus to infection with R. tsutsugamushi was 30%. Non-immune personnel, when infected, were more likely to develop scrub typhus than were those who had previously been infected. There was a correlation between clinical illness and high antibody titers developed in response to the infection.

Humans↗
PubMed1977

Indirect immunofluorescence antibodies in natural and acquired Rickettsia tsutsugamushi infections of Philippine rodents.

Antibodies against Rickettsia tsutsugamushi detected by the indirect fluorescent-antibody test (IFAT) were present in most rats trapped from a human focus of scrub typhus in the Philippines. Rickettsiae were isolated only from rats with positive IFATs. Naturally acquired antibodies persisted for at least 11 months, and antibodies resulting from experimental infections of rats persisted for at least 7 months. A common Philippine rodent, Rattus mindanensis, tolerated experimental infections with both local and standard Karp strains of R. tsutsugamushi, and such infections always produced a positive IFAT.

Animals↗
PubMedDate not supplied

Penicillinase-producing Neisseria gonorrhoeae in various seaport cities of Latin America.

One hundred fifteen acute cases of gonorrhea were documented in U.S. military personnel during a five-month cruise in which 22 port cities of Latin America were visited in 1985. Penicillinase-producing Neisseria gonorrhoeae (PPNG) was isolated from 23 (20%) of the 115 cases. No penicillin-resistant, beta-lactamase-negative gonococci were encountered. None of the ten cases of gonorrhea acquired in the Caribbean region was due to PPNG. In South America, the PPNG infection rate was 35% (19/54) in ports along the Pacific Ocean and 8% (4/51) in those along the Atlantic. Infections incurred in four cities of three countries on the Pacific coast of the South American continent accounted for 78% of all PPNG isolates. Although the study did not deal directly with infections in the local populations, the data suggest that PPNG are common in coastal South America and that hyperendemic foci exist in some cities of the continent's western coast.

Anti-Bacterial Agents↗