Evolution and clonal traits of Mycobacterium tuberculosis complex in Guinea-Bissau

Two hundred twenty-nine consecutive isolates of Mycobacterium tuberculosis complex from patients with pulmonary tuberculosis in Guinea-Bissau, which is located in West Africa, were analyzed for clonal origin by biochemical typing and DNA fingerprinting. By using four biochemical tests (resistance to thiophene-2-carboxylic acid hydrazide, niacin production, nitrate reductase test, and pyrazinamidase test), the isolates could be assigned to five different biovars. The characteristics of four strains conformed fully with the biochemical criteria for M. bovis, while those of 85 isolates agreed with the biochemical criteria for M. tuberculosis. The remaining 140 isolates could be allocated into one of three biovars (biovars 2 to 4) representing a spectrum between the classical bovine (biovar 1) and human (biovar 5) tubercle bacilli. By using two genotyping methods, restriction fragment length polymorphism analysis with IS6110 (IS6110 RFLP analysis) and spoligotyping, the isolates could be separated into three groups (groups A to C) of the M. tuberculosis complex. Group A (n = 95), which contained the majority of classical human M. tuberculosis isolates, had large numbers of copies of IS6110 elements (mean number of copies, 9) and a distinctive spoligotyping pattern that lacked spacers 33 to 36. Isolates of the major group, group B (n = 119), had fewer IS6110 copies (mean copy number, 5) and a spoligotyping pattern that lacked spacers 7 to 9 and 39 and mainly comprised isolates of biovars 1 to 4. Group C isolates (n = 15) had one to three IS6110 copies, had a spoligotyping pattern that lacked spacers 29 to 34, and represented biovar 3 to 5 isolates. Four isolates whose biochemical characteristics conformed with those of M. bovis clustered with the group B isolates and had spoligotype patterns that differed from those previously reported for M. bovis, in that they possessed spacers 40 to 43. Interestingly, isolates of group B and, to a certain extent, also isolates of group C showed a high degree of variability in biochemical traits, despite genotypic identity in terms of IS6110 RFLP and spoligotype patterns. We hypothesize that isolates of groups B and C have their evolutionary origin in West Africa, while group A isolates are of European descent.

Molecular characterization of human immunodeficiency virus (HIV)-1 and -2 in individuals from guinea-bissau with single or dual infections: predominance of a distinct HIV-1 subtype A/G recombinant in West Africa

Guinea-Bissau in West Africa has the highest prevalence of human immunodeficiency virus (HIV)-2 infection in the world, but recently the HIV-1 prevalence increased rapidly with the subsequent appearance of HIV-1 and HIV-2 dual infections. Information about the genetic subtypes of HIV in the region is limited. Therefore, we characterized the env V3 region of HIV-1 and HIV-2 variants through direct DNA sequencing of peripheral blood mononuclear cell samples from 18 individuals with HIV-1 only and 9 individuals with dual infection. Phylogenetic analyses of these new sequences and database sequences from other West African countries showed that all HIV-1 and HIV-2 sequences from singly as well as dually infected individuals, except one, clustered among HIV-1 subtype A and HIV-2 subtype A, respectively. Importantly, a majority of the HIV-1 sequences from Guinea-Bissau and neighbouring countries were closely related with the isolates IbNG, DJ263, and DJ264, which share a common subtype A/G recombination pattern. Analysis of pol gene sequences from selected HIV-1 variants showed that "IbNG-like" viruses in Guinea-Bissau are also recombinant, indicating that the HIV-1 epidemic in Guinea-Bissau and neighbouring countries is dominated by an epidemic spread of a distinct subtype A/G recombinant, which is strikingly similar to the epidemic spread of a subtype A/E recombinant in Southeast Asia. Furthermore, the HIV-1 and HIV-2 variants carried by individuals with dual infection were intermixed with variants from singly infected individuals, indicating that variants involved in dual and single infections have common epidemiological histories.

Low-dose quinine for treatment of Plasmodium falciparum malaria in Guinea-Bissau

The recommended dose of 10 mg quinine/kg bodyweight 3 times a day for 7 days for treatment of malaria is so high that many patients experience cinchonism. We have earlier obtained good results with 7 days' treatment with 20 mg Quinimax/kg bodyweight divided into 2 daily doses. In order to identify the lowest effective dose, children with symptomatic malaria were treated with quinine twice a day for 7 days. They were assigned to 1 of 3 groups treated daily with 10 mg/kg, 15 mg/kg, or 20 mg/kg bodyweight, respectively; 42, 46, and 34 children, respectively, received treatment and completed 5 weeks of follow-up. The cumulative percentages of all children with parasitaemia during follow-up on day 28 or before were 33%, 13% and 12%, respectively. Treatment with 10 mg quinine salt/kg daily for 7 days gave a significantly higher rate of recrudescence than did treatment with 15 or 20 mg/kg daily. Thus at least 15 mg of quinine salt/kg bodyweight daily should be recommended for treatment of symptomatic Plasmodium falciparum malaria in Guinea-Bissau.

Community-based randomized controlled trial of reduced osmolarity oral rehydration solution in acute childhood diarrhea

OBJECTIVE

The standard oral rehydration solution (ORS) recommended by WHO and UNICEF does not reduce the volume or frequency of stools or the length of the episode. Hospital-based studies from developing and developed countries and intestinal perfusion studies suggest a beneficial effect on water and sodium absorption with reduced osmolarity ORS as compared with standard ORS. We conducted a community-based study comparing the efficacy of reduced osmolarity ORS (224 mmol/l) with standard ORS (311 mmol/l) in acute childhood diarrhea in a West African community.

METHODS

Infants and toddlers age 0 to 30 months having 738 episodes of diarrhea identified by weekly household visits were randomly assigned to treatment with either standard ORS (n = 376) or reduced osmolarity ORS (n = 362). The children were followed by daily home visits to assess ORS intake and clinical characteristics. Duration of diarrhea was compared by proportional hazards regression analysis, the hazard ratio being interpreted as the relative recovery rate between the children receiving the two types of ORS. Because earlier reports have suggested that weaning status might be an important modifier for the performance of reduced osmolarity ORS, the effect was assessed overall and as an interaction between type of ORS and weaning status and age. Maternal satisfaction was assessed in a paired analysis among mothers whose children participated at least twice in the study.

RESULTS

In the overall analysis reduced osmolarity ORS was as efficacious as standard ORS as assessed by duration of diarrheal episode and total number of stool evacuations on Days 1 and 2. Non-breast-fed toddlers (i.e. children ages 12 to 30 months) treated with reduced osmolarity ORS had significantly shorter diarrheal episodes [1.14 days vs. 1.78 days with standard ORS; hazard ratio, 1.50; 95% confidence interval (CI), 1.07 to 2.09] and lower total number of stool evacuations on Days 1 and 2 (3.9 stool evacuations vs. 5.0 stool evacuations with standard ORS; ratio of geometric means, 0.77; 95% CI 0.60 to 1.01). No significant difference was found for breast-fed toddlers or for infants. There was no statistically significant difference in the ORS intake between the two treatment groups. The odds ratio for the mother preferring reduced osmolarity ORS to standard ORS was 1.92 (95% CI 0.97 to 3.85).

CONCLUSIONS

Reduced osmolarity ORS was as efficacious as standard ORS. Non-breast-fed children treated with reduced osmolarity ORS had significantly shorter diarrheal episodes and a tendency toward lower stool frequency. These findings may be of importance, especially in developing countries where early weaning is common.

Comparative evaluation of 14 immunoassays for detection of antibodies to the human T-lymphotropic virus types I and II using panels of sera from Sweden and West Africa

BACKGROUND

A new generation of assays for the detection of human T-lymphotropic virus types I and II (HTLV-I/II) antibodies has been released. These assays incorporate HTLV-I- and HTLV-II-specific antigens, and some are based on new assay principles. Comparative evaluation data that include these new as well as previous assays are limited.

STUDY DESIGN AND METHODS

Fourteen HTLV antibody assays were evaluated by using well-characterized panels of sera from Guinea-Bissau, West Africa, and Sweden. The sera included 127 HTLV-I-positive and 62 HTLV-II-positive specimens, as well as 919 consecutive negative samples.

RESULTS

The sensitivity for HTLV-I was 100 percent for all assays, except one, which repeatedly missed one sample. The sensitivity for HTLV-II varied between 86 percent and 100 percent. In general, new-generation assays incorporating HTLV-II-specific antigens, and some of which are based on new assay principles, had a higher sensitivity for HTLV-II than previous assays, which mainly are based on HTLV-I antigens. The specificity was generally higher for new assays than for the previous versions. Testing of Swedish blood donor sera gave higher specificities (94-100%) than did that of African specimens (90-99.7%). Most assays had low delta values (DVs), although there was a tendency toward increased DVs for the new generation of assays. Only two of the new generation of assays came close to a combination of high sensitivity for both HTLV-I and HTLV-II, high specificity, positive and negative predictive values, and high DVs.

CONCLUSION

The sensitivity for HTLV-I was generally high and appears to have improved for HTLV-II with the introduction of a new generation of assays incorporating HTLV-II-specific antigens. However, some assays still give false-negative results on HTLV-II-positive specimens. The specificities and the DVs were generally higher for the new assays than for the previous versions.

Child survival in children born to HIV-2 infected women in Guinea-Bissau, West Africa

We have retrospectively studied the effect of maternal HIV-2 infection and other risk factors on child survival at a family planning centre in Bissau, Guinea-Bissau. A total of 2109 women were included, and the seroprevalence of HIV-2 was 5.7%. Overall child mortality of all live births (n=5912) reported by the women (standardized for age of the mother) was slightly higher among children of HIV-2 seropositive mothers (16.3%) compared with children of HIV seronegative women (14.6%) (not significant). There was a significant association between low level of maternal education and increased child mortality, but no difference in the level of education was found between HIV-2 seropositive and seronegative women.

Trends and interaction of HIV-1 and HIV-2 in Guinea-Bissau, west Africa: no protection of HIV-2 against HIV-1 infection

OBJECTIVES

To study trends in the prevalence and incidence of HIV-1 and HIV-2 infections in Guinea-Bissau over the last 7 years, and to evaluate the protective effect of HIV-2 against HIV-1 infection.

DESIGN

Prospective follow-up of a cohort of police officers in Guinea-Bissau, and sentinel surveillance of pregnant women in Bissau.

METHODS

Participants in the police cohort were tested regularly for antibodies to HIV and Treponema pallidum, and information about sexual risk behaviour and a history of sexually transmitted diseases was obtained. Simultaneously, pregnant women at the maternity wards at the National Hospital in Bissau were screened annually for HIV antibodies. To evaluate changes in prevalence and incidence of HIV in the police cohort, the study period was divided into three time strata with 2-3 years in each stratum. For the evaluation of a protective effect of HIV-2 on subsequent HIV-1 infection, two multivariate Poisson regression models were constructed, adjusting for different selected confounding variables.

RESULTS

Between 1990 and 1997, 2637 police officers were included in the cohort study, 90.7% of whom were male. The overall prevalence of HIV-1 was 0.9%, of HIV-2 it was 9.7% and of HIV-1 and HIV-2 dual reactivity it was 0.5%. For pregnant women the prevalence rates were 0.9, 5.5 and 0.2% for HIV-1, HIV-2 and dual reactivity respectively. The prevalence of HIV-1 increased significantly whereas the prevalence of HIV-2 declined significantly during the study period, among both police officers and pregnant women. The total incidence of HIV-1 and HIV-2 was 0.74 and 0.83 per 100 person-years respectively in the police cohort. The incidence of HIV-1 increased slightly from 0.62 to 0.78 per 100 person-years (not significant), whereas the incidence of HIV-2 declined significantly from 0.90 to 0.35 per 100 person-years over the study period. Seven police officers seroconverted from HIV-2 to dual reactivity (1.22 per 100 person-years). The adjusted incidence ratio of acquiring HIV-1 infection among HIV-2-positive subjects compared with HIV-negative subjects was 1.65 [95% confidence interval (CI), 0.73-3.74] and 1.98 (95% CI, 0.80-4.87), depending on the confounding variables included.

CONCLUSIONS

Our study shows an increasing prevalence of HIV-1 and a decreasing prevalence of HIV-2 in Guinea-Bissau. The incidence of HIV-2 declined significantly whereas the incidence of HIV-1 was relatively stable over the study period. No protective effect of HIV-2 against subsequent HIV-1 infection was observed, instead HIV-2-positive subjects had a tendency towards higher risk of acquiring HIV-1 infection compared with seronegative subjects.

Early two-dose measles vaccination schedule in Guinea-Bissau: good protection and coverage in infancy

BACKGROUND

Previous studies from Africa have suggested that there is little benefit to be gained from early two-dose measles vaccination schedules. Two-dose schedules have been associated with no improvement in coverage due to immunization of the same individuals on both occasions, low return rate, high refusal rate, low vaccine efficacy, and fear of blunting of the antibody response. Because of the poor results achieved previously with two-dose measles vaccination schedules, we studied patterns of participation, reasons for non-participation, vaccination coverage and relative efficacy of a one-dose versus a two-dose schedule in connection with the implementation of an early two-dose trial in Guinea-Bissau.

METHODS

Children born from September 1994 to January 1996 were randomized into two groups receiving either two doses of measles vaccine at 6 and 9 months or one dose of inactivated polio vaccine (IPV) at 6 months and measles vaccine at 9 months.

RESULTS

At 6 months of age 86% (1869/2181) of the children participated, and at 9 months of age participation was 87% (1775/2035). The return rate for obtaining a second dose of vaccine was 93% (1647/1773). The main reason for not participating was travelling (78%). Around 50% of those who did not take part in one vaccination took part in the other. When only children participating the first time they were called for a measles vaccination were included, the measles vaccination coverage in the one-dose group was 59% versus 80% in the two-dose group, i.e. a 50% reduction in the risk of not being vaccinated (relative risk [RR] 0.50; confidence interval [CI]: 0.43-0.57). Few measles cases have occurred in the study area since the implementation of the trial making precise estimation of the relative efficacy of the two vaccine strategies difficult, but all seven clinically diagnosed measles cases occurred in the one-dose group making the relative efficacy for the two-dose group compared with the one-dose group 100% (95% CI: 35%-100%; two-tailed P = 0.016). When including maternal reports, the relative efficacy was 90% (95% exact confidence interval; two-tailed P = 25%-97%, P = 0.022).

CONCLUSION

In this study of a two-dose measles immunization schedule at 6 and 9 months of age there was no sign of low participation or poor return rates. The risk of not being vaccinated was lower in the two-dose group than in the one-dose group, and the relative efficacy of a two-dose versus a one-dose schedule was high. Although our results were obtained within a trial where dedicated personnel informed every participant personally about the study, we believe our results indicate that with thorough information about the population it may be possible to achieve a higher coverage with a two-dose measles vaccination schedule than a one-dose schedule. A two-dose schedule may be a feasible way to resolve the problems of low coverage and severe measles infection among infants.

Clinical features, immunological changes and mortality in a cohort of HIV-2-infected individuals in Bissau, Guinea-Bissau

Clinical symptoms and immunological changes associated with HIV-2 infection were studied in a cohort of police officers in Guinea-Bissau. HIV-related symptoms were classified according to the WHO clinical staging system. The inclusion period was from January 1990 to January 1997, and among 2637 subjects included (90.7%M, 9.3%F), the prevalence of HIV-1, HIV-2 and dual reactivity to both HIV-1 and HIV-2 was 0.9%, 9.7% and 0.5%, respectively. Weight loss > 10%, diarrhoea or fever > 1 month, generalized lymphadenopathy and generalized pruritic dermatitis were significantly associated with HIV-2 infection as well as suppression of CD4 cells as compared with HIV-negative controls. Females had significantly higher CD4 cell counts than males, both among HIV-negative and HIV-2-positive asymptomatic individuals. The mortality rates/100 person-years (p.y.) were 0.4 in HIV-negative and 2.6 in HIV-2-positive subjects, giving an age-adjusted mortality rate ratio of 6.6 (95% CI, 4.0-10.9; p < 0.001). The mortality rate among HIV-2-infected individuals varied considerably in different stages of the WHO clinical staging system; 1.7 and 8.0/100 p.y. in stage 1 and 3, respectively.

Mortality among human immunodeficiency virus type 2-positive villagers in rural Guinea-Bissau is correlated with viral genotype

We present the results of a 6-year study of 131 human immunodeficiency virus (HIV) type 2 (HIV-2)-infected individuals from a rural population in Guinea-Bissau. Proviral DNA sequences 1.3 kb in length were obtained from each individual and, together with clinical data, including proviral load and CD4 and CD8 levels, were used to assess whether viral genotype influences clinical outcome. With a phylogenetic model, a correlation was found between viral genotype and mortality; this correlation was not due to confounding factors, such as age-specific viral strains or cohabitation of patients. The data provide strong evidence for the involvement of viral genetic factors in determining HIV disease progression in vivo. The pattern of association found suggests that virulence factors are multiple and scattered throughout the HIV-2 genome and can be rapidly gained or lost by the virus through a combination of mutation and recombination. These findings may lead to the identification of viral determinants of HIV disease progression.

Declining HIV-2 prevalence and incidence among men in a community study from Guinea-Bissau

OBJECTIVE

To assess the present level of HIV-2 infection in an adult population in Bissau and to evaluate sex and age-specific changes in HIV-2 prevalence and incidence between 1987 and 1996.

DESIGN AND METHODS

Sex and age-specific changes in HIV-2 prevalence were evaluated comparing a survey from 1987 in a sample of 100 houses with a survey performed in 1996 in an independent sample of 212 houses from the same study area. HIV-2 incidence rates were examined in an adult population (age > or = 15 years) from 100 randomly selected houses followed with four consecutive HIV serosurveys from 1987 to 1996.

RESULTS

The HIV-2 prevalence in 1996 was 6.8% (men, 4.7%; women, 8.4%). Compared with the 1987 survey there was a significant decrease in prevalence among men [age-adjusted relative risk (RR), 0.50; 95% confidence interval (CI), 0.31-0.83], whereas it remained unchanged in women (RR, 1.00; 95% CI, 0.67-1.48). The male-to-female RR decreased from 0.99 (95% CI, 0.61-1.61) in 1987 to 0.51 (95% CI, 0.34-0.76) in 1996. The overall annual incidence rate was 0.54 per 100 person-years of observation (PYO), being higher in women (0.72 per 100 PYO) than in men (0.31 per 100 PYO). With the observation time divided into an early and a late period, there was a decrease in incidence with time among men (0.66 to 0.00 per 100 PYO), but no major change among women (0.59 to 0.85 per 100 PYO). The two trends differed significantly (P = 0.03). We observed a higher annual incidence rate amongst older women aged > 44 years (1.77 per 100 PYO) than among younger women (0.55 per 100 PYO; P = 0.05).

CONCLUSION

There are no signs of an epidemic spread of HIV-2 in Bissau even though the HIV-1 prevalence is increasing rapidly. A significant reduction in the male HIV-2 prevalence and incidence rates has resulted in a major shift in the pattern of spread of HIV-2, from being equally distributed to being predominantly a female infection. Currently, older women in particular seem to have a high risk of getting infected.

How and why public sector doctors engage in private practice in Portuguese-speaking African countries

OBJECTIVE

To explore the type of private practice supplementary income-generating activities of public sector doctors in the Portuguese-speaking African countries, and also to discover the motivations and the reasons why doctors have not made a complete move out of public service.

DESIGN

Cross-sectional qualitative survey.

SUBJECTS

In 1996, 28 Angolan doctors, 26 from Guinea-Bissau, 11 from Mozambique and three from S Tomé and Principe answered a self-administered questionnaire.

RESULTS

All doctors, except one unemployed, were government employees. Forty-three of the 68 doctors that answered the questionnaire reported an income-generating activity other than the one reported as principal. Of all the activities mentioned, the ones of major economic importance were: public sector medical care, private medical care, commercial activities, agricultural activities and university teaching. The two outstanding reasons why they engage in their various side-activities are 'to meet the cost of living' and 'to support the extended family'. Public sector salaries are supplemented by private practice. Interviewees estimated the time a family could survive on their public sector salary at seven days (median value). The public sector salary still provides most of the interviewees income (median 55%) for the rural doctors, but has become marginal for those in the urban areas (median 10%). For the latter, private practice has become of paramount importance (median 65%). For 26 respondents, the median equivalent of one month's public sector salary could be generated by seven hours of private practice. Nevertheless, being a civil servant was important in terms of job security, and credibility as a doctor. The social contacts and public service gave access to power centres and resources, through which other coping strategies could be developed. The expectations regarding the professional future and regarding the health systems future were related mostly to health personnel issues.

CONCLUSION

The variable response rate per question reflects some resistance to discuss some of the issues, particularly those related to income. Nevertheless, these studies may provide an indication of what is happening in professional medical circles in response to the inability of the public sector to sustain a credible system of health care delivery. There can be no doubt that for these doctors the notion of a doctor as a full-time civil-servant is a thing of the past. Switching between public and private is now a fact of life.

Restricted distribution of S-phase cells in the anterior subventricular zone of the postnatal mouse forebrain

The anterior subventricular zone (SVZa) is the site for postnatal neurogenesis of interneurons of the olfactory bulb (OB). Concurrently or after proliferation, neuronal precursors therein migrate within it to reach the OB, an event known as the rostral migratory stream (RMS). We used bromodeoxyuridine (BrdU) incorporation with short survival times to investigate the distribution of S-phase nuclei in the SVZa/RMS of the postnatal mouse. We observed that they were distributed along a radial, outside-in, decreasing gradient that persisted until postnatal day 10 (P10), then faded away to finally disappear by P16. After longer post-injection survival times labeled cell distribution became homogeneous. GFAP-positive glia are present at the periphery but not at the core of the SVZa. Our results represent the first evidence of a discrete spatial organization of a cell cycle phase within the SVZ, and also suggests a segregation of proliferating and migrating cells in the rostral migratory stream of the early postnatal mouse.

HTLV-1 infection in a population-based cohort of older persons in Guinea-Bissau, West Africa: risk factors and impact on survival

In 1989, a population-based cohort of persons aged > or = 50 years was established in an urban area of Guinea-Bissau, West Africa. Overall, 346 persons were interviewed in detail about risk behaviors and had capillary blood drawn. Among women, 12.4% were HTLV-1 seropositive, compared with 4.6% in men. No HTLV-2 was found. Seropositivity varied considerably according to place of birth and ethnic group. In women, but not in men, HTLV-1 seropositivity was strongly associated with early sexual debut (10-14 yrs, 33.3%; 15-17 yrs, 26.0%; 18-20 yrs, 6.5%; 21+ yrs, 0%; ptrend = 0.001), lifetime number of male partners (ptrend = 0.006), and the male partner's number of co-wives (ptrend = 0.006). There was also a 3.1-fold increased risk of being HTLV-1 seropositive if the woman was also HIV-2 seropositive. In a multivariate-risk-factor analysis, the strongest association with HTLV-1 was a history of having been bitten by a monkey (n = 11; combined OR adjusted = 10.1; 95% CI 2.3-44.4). Ornamental scarification was associated with a 3.3-fold increased risk. Ethnic affiliation also significantly influenced the risk of being HTLV-1 seropositive. Follow-up performed in January 1996 revealed no difference in survival between HTLV-1-seropositive and -seronegative individuals over 6 years (rate ratio = 1.4, 95% CI 0.7-2.8). In conclusion, this population, which has very high HIV-2 seroprevalence, is also highly endemic for HTLV-1. Whereas sexual behaviors are clearly important for HTLV-1 spread in women, non-sexual risk factors were the only ones of potential importance in men. HTLV-1 had no impact on survival in this older population.

Evaluation of 14 commercial HIV-1/HIV-2 antibody assays using serum panels of different geographical origin and clinical stage including a unique seroconversion panel

The performance of 14 commercially available HIV-1/2 antibody assays were compared using well-characterized serum panels containing in total 1500 1800 sera. The panels included consecutive HIV-negative blood donor sera from Sweden, unselected blood donor and patient sera from Tanzania and unselected sera from outpatient clinics in Guinea-Bissau. Furthermore selected HIV-1 antibody positive sera from Sweden and Tanzania and HIV-2 antibody positive sera from Guinea-Bissau were included in the panels. The HIV-1 antibody positive sera were from individuals at various stages of HIV infection, from primary infection, to asymptomatic phase and late stage disease. 12 of the 14 assays identified correctly all HIV-1 and HIV-2 antibody positive sera. One Tanzanian HIV-1 antibody positive sample with complete banding pattern on Western blot was not detected by two of the ELISAs employing synthetic peptides. There were small differences in sensitivity between the assays when used for analysis of seroconversion panels. The most sensitive assay, Abbott IMx HIV-1/HIV-2 III Plus detected antibodies in all nine samples collected from four individuals during the first week after onset of symptoms of primary HIV-1 infection. Most of the assays became reactive during the second week after onset of symptoms and the least sensitive assays were reactive from the third week. The assays showed a high specificity ranging from 99.2 to 100% when used for analysis of Swedish blood donor sera, while most of the assays showed a significantly lower specificity, 91.9-99.6%, when used for testing African specimens.

Increased prevalence of HIV-2 infection in hospitalized patients with severe bacterial diseases in Guinea-Bissau

We studied the association between HIV-2 infection and bacterial pneumonia, sepsis or pyomyositis, as well as the influence of HIV-2 infection on the clinical outcome in patients with these bacterial infections. A total of 201 consecutive hospitalized patients were included at the Simao Mendes National Hospital in Bissau, Guinea-Bissau. Age- and sex-matched controls were selected from an ongoing census in a semi-urban area of Bissau. Among 201 cases with such bacterial infection the prevalence of HIV-1 was 5.4%, HIV-2, 27.9%, and both HIV-1 and HIV-2 reactivity 6.4%. Among controls, the corresponding prevalence rates were significantly lower, 1.5%, 9.0% and 1.0%, respectively. A total of 140, 31 and 30 cases of pneumonia, sepsis and pyomyositis were included, and the differences in prevalence of HIV-2 compared with the controls also remained significant for each diagnosis separately. Lymphocyte subsets were determined in 93 consecutive patients, and the CD4 cell counts and CD4/CD8 lymphocyte ratios were markedly suppressed in the HIV-2-seropositive group. Due to excess mortality in the seropositive groups with sepsis (75.0%) and pyomyositis (25.0%), the mortality during hospitalization was significantly higher among HIV-2 infected compared to HIV-negative patients. Among cases of pneumonia the mortality was low in the HIV-2-seropositive (2.9%) as well as in the HIV-seronegative (3.4%) group.

Field evaluation of alternative testing strategies for diagnosis and differentiation of HIV-1 and HIV-2 infections in an HIV-1 and HIV-2-prevalent area

OBJECTIVE

To identify cost-efficient alternative antibody testing strategies for screening, confirmation and discrimination of HIV-1 and HIV-2 infections, including rapid simple tests (RST) as well as enzyme-linked immunosorbent assays (ELISA), in a HIV-1 and HIV-2-prevalent area.

DESIGN

Evaluation and comparison of anti-HIV-1/2 assays, adhering to the World Health Organization recommendations for alternative confirmatory strategies, using banked and prospectively collected specimens in Guinea-Bissau.

METHODS

A total of 1110 consecutive sera from Bissau were included in the first phase, of which 198 (17.8%) were HIV-seropositive: 52 (4.7%) HIV-1, 120 (10.8%) HIV-2, and 26 (2.3%) HIV-1/HIV-2 dually reactive. In addition, 95 selected HIV-positive specimens were included for study of sensitivity and cross-reactivity between HIV-1 and HIV-2. Western blot was used as a gold standard for confirming the reactivity of the specimens. All specimens were screened by two assays. Enzygnost ELISA and Capillus RST. Samples reactive by any of the screening assays were further tested by assays chosen for confirmation: UBI ELISA, Innotest ELISA Recombigen RST, Multispot RST and Immunocomb RST. The confirmatory RST as well as Wellcozyme Recombinant HIV-1 ELISA, PEPTI-LAV and INNO-LIA were also used to study differentiation between HIV-1 and HIV-2.

RESULTS

The sensitivities of all assays were 100%. The specificities of the screening assays at initial and repeated testing were 98.0 and 99.7%, respectively, for Enzygnost and 99.8 and 99.9%, respectively, for Capillus. The various combinations of two or three assays showed specificities of 99.2-100%. Several possible combinations of assays were identified where a specificity of 100% and good differentiation between HIV-1 and HIV-2 was achieved. Significant differences in the capacity to discriminate were noted; Immunocomb and PEPTI-LAV had the lowest number of dual-reactive results. A follow-up study of 1501 consecutive samples tested with the strategy chosen for routine use showed a sensitivity and specificity comparable to ELISA and Western blot.

CONCLUSION

High sensitivities and specificities were obtained with various combinations of assays including RST as well as ELISA, and these procedures are well suited for field use in Africa. Serodiagnostic strategies for HIV can be based on RST alone and differentiation between HIV-1 and HIV-2 can be achieved as part of these strategies. Large differences in the capacity of individual assays to discriminate between HIV-1 and HIV-2 were observed.

HIV-2 genetic variation and DNA load in asymptomatic carriers and AIDS cases in Guinea-Bissau

The purpose of this study was to document which genetic subtypes of HIV-2 are present in Guinea-Bissau and to investigate whether asymptomatic HIV-2 carriers and AIDS patients carry distinct genetic variants. A secondary aim was to correlate proviral DNA load to clinical and immunologic status of the patients. Thirty-eight asymptomatic HIV-2 carriers and 11 AIDS patients from Bissau, Guinea-Bissau were included in a cross-sectional study in which HIV-2 env V3 sequences, HIV-2 DNA load, and CD4-positive (CD4+) lymphocyte counts were determined. Phylogenetic analyses showed that all investigated subjects carried subtype A HIV-2 variants and that the sequences from AIDS patients and asymptomatic carriers did not form distinct subclusters in the tree. As expected, patients with AIDS had significantly higher median HIV-2 DNA load than did asymptomatic carriers (4.6 vs. 2.0 log10 HIV-2 DNA copies/10(6) CD4+ lymphocytes). Our study indicates that the HIV-2 epidemic in Guinea-Bissau is almost exclusively caused by subtype A HIV-2 variants and that the HIV-2 infections among the asymptomatic carriers and AIDS cases included in the study do not have distinct epidemiologic histories.

HIV type 2 pathogenicity is not related to subtype in rural Guinea Bissau

Data from an MRC case-control study in rural Guinea Bissau suggest older HIV-2 carriers (aged 55 to 80 years) appear, over a period of 2 years, to have a mortality similar to that of uninfected controls, whereas in HIV-2 carriers under the age of 55 there is a significantly higher mortality, compared with uninfected controls. Genotyping of viruses from both groups revealed only subtype a to be circulating. Thus, although putative nonpathogenic HIV-2 subtypes have been described in patients from West Africa, these do not appear to be contributing significantly to the nonpathogenic clinical phenotype in this population.

9-year HIV-2-associated mortality in an urban community in Bissau, west Africa

BACKGROUND

Community studies with 1-3 years of follow-up have reported four to five times higher mortality in HIV-2-infected than in uninfected adults. In a cohort study of HIV-1, an increasing difference in mortality rates of HIV-1-infected and uninfected individuals is expected over time, because of rising mortality with advancing HIV-1 infection. We therefore investigated long-term survival of HIV-2-infected adults.

METHODS

Adults enrolled in 1987 in a community study of HIV-2 infection in Guinea-Bissau were followed up with serological surveys in 1989 and 1992. Survival was assessed in 1995, 9 years after enrollment.

FINDINGS

The annual incidence of HIV-2 was 0.7% for adults and tended to be higher for older individuals than for participants aged 15-44 years (relative risk 3.21 [95% CI 0.91-11.37]). With control for age, HIV-2-infected adults had twice as high mortality as uninfected individuals (mortality ratio 2.32 [1.18-4.57]); the mortality ratio was highest in the first year of the study (4.50 [1.31-15.43]). The difference between infected and uninfected individuals was stronger for adults under 45 years of age (mortality ratio 4.72 [1.86-11.97]) than for older people (1.35 [0.51-3.56]). HIV-2-infected individuals living with an infected spouse had significantly higher mortality than HIV-2-infected individuals living with an uninfected spouse (p = 0.027).

INTERPRETATION

HIV-2-associated mortality is not increasing with length of follow-up. Mortality in HIV-2-infected adults is only twice as high as that in uninfected individuals. In the majority of adults, HIV-2 has no effect on survival.

Serial CD4 and CD8 T-lymphocyte counts and associated mortality in an HIV-2-infected population in Guinea-Bissau

In an urban community in Guinea-Bissau, we followed a cohort of human immunodeficiency virus type 2 (HIV-2) seropositive individuals (N = 47) and seronegative controls (N = 82). T-lymphocyte subset determinations were done in 1988, 1990, and 1992. Serial determinations of CD4 percentages, CD8 percentages, and CD4/CD8 ratios for the same individual were stable for 31 seropositive and 51 seronegative individuals with repeated measurements. We found no significant differences in the changes during a 2- or 4-year period in CD4 percentages, CD8 percentages, absolute CD8 T-lymphocyte counts, CD4/CD8 ratio, white blood cell counts, lymphocyte percentages, and absolute lymphocyte counts for HIV-2-seropositive compared with HIV-2-seronegative individuals. Only absolute CD4 T-lymphocyte counts changed more for the HIV-2-seropositive than for HIV-2-seronegative individuals (p = 0.037). HIV-2-infected individuals who lived with an HIV-2-infected spouse had a lower CD4/CD8 ratio and had higher mortality than HIV-2 infected individuals who lived with an uninfected spouse. However, there were no significant differences in immunological and hematological values for the 8 HIV-2 seropositive individuals who died and the 39 who survived in the 8-year follow-up period. In conclusion, progression of immunosuppression in HIV-2 infection seems to be slower than in HIV-1 infection and may not be inevitable in all individuals.