Human immunodeficiency virus type 1 IgA antibody in breast milk and serum.

Breast-feeding plays a potentially significant role in mother to child transmission of human immunodeficiency virus type 1 (HIV-1). The additional transmission risk attributable to breast-feeding and the factors that enhance or inhibit transmission are presently unknown. One mechanism by which breast milk might inhibit HIV-1 transmission is the presence of specific antibodies directed against HIV-1 in breast milk of seropositive mothers. In this study serum and breast milk samples from women in Nairobi, Kenya, were tested to determine the prevalence of HIV-1 IgA antibodies. A Western blot test developed in our laboratory was used to detect anti-HIV-1 immunoglobulin A in serum and anti-HIV-1 secretory IgA (sIgA) in breast milk. Ninety-four percent of 63 HIV-1 seropositive women had anti-HIV-1 IgA in serum and 59% had anti-HIV-1 sIgA in their breast milk. No significant associations with maternal characteristics or serum anti-HIV-1 IgA or IgG banding patterns and the presence of anti-HIV-1 sIgA in breast milk were found. No protective effect of anti-HIV-1 sIgA was seen regarding mother to child transmission; however, further studies are necessary to determine the effect of these antibodies in maternal sera or in breast milk on the efficacy of HIV-1 transmission.

An epidemic of Mycoplasma pneumoniae in Manitoba: A serological report.

OBJECTIVES: To report an epidemic of Mycoplasma pneumoniae in Manitoba and to discuss the limitations of the serodiagnostic tests used. DESIGN: A retrospective analysis of the results of a province-wide serological testing for respiratory infections caused by M pneumoniae, using a complement fixation test and an indirect immunofluorescent antibody test for the detection of immunoglobulin (Ig) M antibodies. MATERIAL: From April 1, 1987, to March 31, 1991, 12,804 sera were tested and a serological diagnosis of recent M pneumoniae infections were established in 509 (3.97%). From April 1 to September 30, 1991, an additional 2088 persons were tested; the 158 (7.5%) recent cases of M pneumoniae were subjected to analysis. RESULTS: Compared with the previous three years, an increase in the number of recent cases of M pneumoniae was first noticed in July 1990 which persisted until September 1991. Of 856 single sera tested, 59 (6.8%) were recent M pneumoniae infections and 56 (96.1%) of these were positive for IgM antibodies. Of the 616 persons who submitted paired sera, 99 (16%) were recent infections, but only 46 (46.4%) had IgM antibodies. Primary infections (ie, positive for IgM antibodies) were detected in 102 (64.5%) and reinfections (ie, positive complement fixation test only) in the remaining 56 persons with recent M pneumoniae infections. Primary infections were detected more frequently in the 'under 16' than in the 'over 16' year age group (75% versus 55.8% of the recent cases of M pneumoniae in each age group). Reinfections were more common in the older age group. Of the 158 recent cases of M pneumoniae, 30.3% had a pneumonia; of these, 21 (55.2%) were under the age of 16 years. DISCUSSION: M pneumoniae is an important cause of morbidity. Serological tests are used for the diagnosis despite their limitations. The detection of IgM antibodies in acute serum establishes a diagnosis of primary M pneumoniae; however, their absence does not exclude M pneumoniae. A second (convalescent) blood test is required to diagnose all primary infections. To diagnose all reinfections, paired sera should be tested by complement fixation. SUMMARY: Manitoba experienced an epidemic of M pneumoniae in 1990-91. Properly selected serological tests can provide a specific and rapid diagnosis.

Increased risk of early measles in infants of human immunodeficiency virus type 1-seropositive mothers.

An increase in illness due to measles is one of the potential consequences of the human immunodeficiency virus (HIV) epidemic in Africa. During a study of perinatal HIV transmission conducted in Kenya, the risk of acquiring measles before vaccination (9 months of age) was found to be 3.8 times higher in infants born to HIV-seropositive mothers than in control infants (10 [9%] of 109 vs. 5 [3%] of 194 infants; P = .02; odds ratio, 3.8; 95% confidence interval, 1.2-13.2). The majority of infants who developed measles in this study had significant sequelae related to their measles infection. The increased risk of measles appeared to be related to relatively lower anti-measles antibody titers detected in cord blood samples of affected infants born to HIV-seropositive mothers. However, 94% of all infants were susceptible to measles on the basis of ELISA testing at age 6 months regardless of maternal HIV serology. These observations highlight the need for improved measles vaccination strategies in Africa and for studies to delineate the effects of HIV infection on the incidence, presentation, and sequelae of childhood infectious illnesses.

Human immunodeficiency virus as a sexually transmitted disease: Manitoba's HIV unlinked seroprevalence study.

OBJECTIVE: To determine the prevalence of human immunodeficiency virus (HIV)-1 infections. DESIGN: An unlinked seroprevalence study on all 'left over' blood submitted for syphilis testing during three consecutive six month periods (April 1, 1990 to September 30, 1991). After the capture of demographic data, sera to be tested for antibodies were stripped of all personal identifiers and assigned a random number. The study fulfilled Canadian ethical guidelines. PARTICIPANTS: Persons with a valid Manitoba Health Services Commission number were included only once in a study year. Persons were enrolled into one of five categories: infants, injection drug users, pregnant women, persons investigated for sexually transmitted diseases (STD) and routine testing. RESULTS: Of the 50,929 persons tested. 133 (0.26%) were positive, a low prevalence of HIV infections. A significant increase in positivity was noticed in the second study period. While 77.7% of those tested were women, only 10 (0.025%) were positive for HIV. The rate of positivity for pregnant women was 0.72 per 10,000 tested. Of the 11,314 males tested. 123 (1.08%) had antibodies. Most of the positives were males in the STD category residing in Winnipeg; for them, the rate of positivity increased by middle age, while the rate of testing decreased with each decade of age (from age 15 to 44 years). DISCUSSION/RECOMMENDATION: This is the first report from a sentinel laboratory in Canada of an unlinked seroprevalence study in persons with STD. Results suggest an urgent need to target strategies for the control of HIV for persons with STD, particularly males in urban centres, by routine HIV testing for STD patients.

Manitoba virus, a new rhabdovirus isolated from Culex tarsalis mosquitoes collected in Manitoba, Canada.

A rhabdovirus, Mn 936-77, was isolated from a pool of two Culex tarsalis collected on August 16, 1977, from Morris, Manitoba. Isolate Mn 936-77 was not pathogenic for suckling Swiss white mice inoculated by the intracerebral route. The virus propagated in three vertebrate cell lines (Vero, primary chick embryo, mouse neuroblastoma), but apparently not in Aedes albopictus C6/36 cells. Isolate Mn 936-77 did not react by amplified enzyme-linked immunosorbant assay with 230 viruses of proven or possible arbovirus etiology or by immunofluorescence with 88 members of the family Rhabdoviridae. Isolate Mn 936-77 appears to be a newly discovered virus for which the name Manitoba virus is proposed.

Impact of human immunodeficiency virus type 1 on tuberculosis in rural Haiti.

We conducted a case-control study to determine the relative and attributable risk of HIV seropositivity for bacillary-positive (smear and/or culture) pulmonary tuberculosis in Haiti. There were 274 patients with tuberculosis and an equal number of control subjects. Antibodies to HIV were present in 67 (24%) patients and eight (3%) control subjects. Odds ratios suggested that the risk of pulmonary tuberculosis was 15.7 times as great (95% confidence interval, 4.8 to 5.0; p less than 0.05) in patients 20 to 39 yr of age who were HIV-seropositive than in HIV-seronegative patients. In contrast, the relative risk in those 40 to 59 yr of age was elevated (3.0 times), though not significantly (lower 95% confidence interval, 0.8). In the 20- to 39-yr age group, 31% of tuberculosis was attributable to HIV infection (95% confidence interval between 23 and 39%). HIV-seropositive and HIV-seronegative patients did not differ with respect to sputum smear positivity. HIV-seronegative patients were twice as likely to be infected with resistant organisms, though this was not significant. We conclude that HIV infection is a major risk factor for pulmonary tuberculosis in young adult residents of Haiti. This, together with the fact that similar proportions of HIV-seropositive and HIV-seronegative patients were potentially infectious, suggests that without vigorous counteraction tuberculosis will become a greater problem for Haiti.

Foodborne gastroenteritis due to Norwalk virus in a Winnipeg hotel.

Within 1 week four separate incidents of gastroenteritis presumed to be foodborne were reported by guests of a Winnipeg hotel. Investigation revealed poor food-handling practices and illness among the kitchen staff. Elevated bacterial counts and Escherichia coli were found in 15 of 24 samples of food tested, and Staphylococcus aureus was isolated from 2 pastry samples. Culture of 14 stool samples for bacteria yielded Clostridium perfringens in 1 sample from a staff member and coagulase-positive S. aureus in 2 samples from staff members and 3 from guests. All of the S. aureus isolates were nonenterotoxigenic and had three different phage patterns. Electron microscopy and immunoelectron microscopy revealed the prototype Norwalk virus in five (56%) of nine stool samples; four samples were from guests, and one was from a kitchen employee. The employee had had diarrhea 24 hours before the first outbreak and was thus believed to be the source of the virus infection, possibly through food handling. This is the first report of Norwalk virus isolation and the first of foodborne Norwalk virus transmission in Canada. A review of foodborne Norwalk virus infections is presented.

An evaluation of measles serodiagnosis during an outbreak in a vaccinated community.

During an epidemic of measles in a vaccinated community, five serodiagnostic tests were performed on 67 persons on whom clinical and epidemiological data were available. The test found most suitable for a rapid diagnosis of measles infection was an Enzyme Linked Immuno Sorbent Assay for the detection of specific IgM antibodies. Only one false negative IgM was recorded. In a group of 45 persons who fulfilled the clinical definition of measles, specific IgM antibodies were detected in the acute phase serum of only 30 (66.6%), of whom 17 were vaccinated. When the convalescent sera were tested, specific IgM antibodies were detected in 25 of the 28 (89.2%) vaccinated, and in 17 of the 17 (100%) non vaccinated clinical cases. A convalescent blood should be tested in persons with a rash illness and no IgM antibodies in the acute phase serum. There were individual variations in the time of appearance of IgM. On the day of onset of rash, IgM antibodies were detected in 7 of the 12 (58.3%). A history of prior vaccination is not always associated with immunity nor with the presence of specific antibodies.

Antibody to hepatitis D virus (delta agent) in selected Manitoba residents, 1974-1986.

The prevalence of antibody to Hepatitis D Virus (HDV) was determined in serum samples collected from 174 Manitoba residents between 1974 and 1986. Anti-delta was detected in five of 123 HBV-infected individuals for an overall prevalence of 4.1%. Three of 54 (5.5%) persons who were sampled in the period 1974-77 were anti-delta positive, as were two of 69 (2.9%) sampled between 1982 and 1986 (p greater than 0.05). Four of 31 (12.9%) acute hepatitis B patients, and one of 92 (1.1%) chronic HBsAg carriers were anti-delta positive. Three of four intravenous drug abusers were anti-delta positive, as compared to two of 69 who denied drug abuse (p less than 0.0005). In three of the four patients with acute delta hepatitis, anti-delta was detectable in convalescent serum only; all four patients made a complete clinical recovery. A possible false-positive reaction for anti-delta was observed in the serum of one of 51 HBsAg negative controls, a patient with acute hepatitis A who was negative for all hepatitis B markers. These results indicate that HDV has been present in Manitoba since at least 1974, though at a relatively low level, and that infection is strongly associated with intravenous drug abuse. Reliable detection of anti-delta in patients with acute delta hepatitis requires the testing of serial serum specimens.

Prevalence of antibodies to Chlamydia trachomatis in healthy population groups in Manitoba.

The prevalence of antibodies to Chlamydia trachomatis was determined in 1877 serum samples from healthy population groups of Caucasians, native Indians and recent Vietnamese immigrants in Manitoba. Testing was done with a commercially available immunofluorescence kit containing C. trachomatis antigen. The presence of antibodies was age-related; a progressive increase in prevalence was observed in children aged 1 to 15 years, and the overall prevalence was higher in female Caucasian blood donors and female Vietnamese immigrants than in males in both groups. However, there was no sex-related difference in prevalence among the subjects undergoing premarital testing or among the native Indians. Antibodies were more prevalent (p less than 0.001) in pregnant than in nonpregnant women matched for race and age, and a relatively high prevalence (66.6%) was found in the cord serum of newborns. The overall prevalence rate of antibodies in all Manitobans was 48.8% (44.9% in men, 55.9% in women and 35.3% in children.