Behaviour change and competitive exclusion can explain the diverging HIV-1 and HIV-2 prevalence trends in Guinea-Bissau

The aim of this study was to determine whether a temporary rise in sexual risk behaviour during war in Guinea-Bissau could explain the observed trends in HIV-1 and HIV-2 prevalence, and to explore the possible contribution of competitive elimination of HIV-2 by HIV-1. A simulation model of the heterosexual transmission of sexually transmitted infections was parameterized using demographic, behavioural and epidemiological data from rural Guinea-Bissau, and fitted to the observed HIV-1 and HIV-2 trends with and without a historic rise in risk behaviour. The observed trends could only be simulated by assuming a temporary rise in risk behaviour. Around 30% of the projected decline in HIV-2 prevalence from a peak of 8.7% to 4.3% in 2010 was due to competitive elimination by HIV-1. Importantly for public health, HIV-1 prevalence was predicted to continue increasing and to become the dominant HIV type by 2010. Data collection is required to validate this prediction.

19 THE EFFECT OF PROGESTERONE ON FOLLICULAR DEVELOPMENT AND PREGNANCY RATE IN BEEF CATTLE

The objective was to determine the effect of the level of progesterone (P4) during the ovulatory wave on fertility. Low v. high progesterone concentrations which were expected to result in high v. low LH pulse-frequency were compared. Lactating, postpartum beef cows (n = 69) at random stages of the estrous cycle were given cloprostenol (PGF; Schering-Plough Animal Health, Pointe-Claire, QC, Canada) twice at an 11-day interval to synchronize ovulation (Day 0 = day of 2nd PGF). Cows were given 1.5 mg estradiol benzoate on Day 10 (7 days after expected ovulation). On Day 10, the Low-P4 group was given PGF and an intravaginal CueMate (Bioniche Animal Health, Belleville, ON, Canada) containing one P4 pod (expected to achieve a P4 plasma level of 1 ng mL–1). The High-P4 group also received a CueMate with one pod on Day 10, but no PGF was administered (i.e., cows were allowed to retain their CL for 4 days after expected emergence of the estradiol-induced wave). On Day 18, CueMates were removed and PGF was administered to both groups. Fifty-four to 56 h later, all animals received 12.5 mg of Lutropin-V (Bioniche) IM and were timed AI (TAI). Dominant follicle diameter was measured on Day 18 and at the time of AI. Pregnancy diagnosis was done by ultrasonography 27 days after AI to compare fertility between groups. Follicle diameter data were analyzed by Student's t-test and pregnancy rate data were compared by the chi-square test. The dominant follicle in the Low-P4 group was larger (P < 0.05) than in the high-P4 group on the day of the CueMate removal (Day 18) and on the day of the TAI (11.8 � 0.4 and 13.7 � 0.5 v. 13.3 � 0.6 and 15.3 � 0.6 in the High-P4 and Low-P4 groups, respectively). Pregnancy rate was similar (P = 0.16) between the groups (High-P4: 55.6% (20/36) and Low-P4: 44.4% (16/33)); however, a larger study is in progress to confirm these results. To conclude, Low-P4 resulted in a larger dominant follicle without any apparent effect on pregnancy rate. The project was funded by Saskatchewan ADF and NSERC. L. Pfeifer is funded through a CAPES scholarship. We acknowledge Schering-Plough and Bioniche for donation of pharmaceuticals.

20 ADMINISTRATION OF FOLLICLE-STIMULATING HORMONE AT CIDR REMOVAL DOES NOT AFFECT THE PREGNANCY RATE IN A CIDR-BASED, COSYNCH PROTOCOL IN LACTATING BEEF COWS

In previous studies, giving eCG at CIDR removal significantly increased the pregnancy rate after timed-AI in beef cows. However, eCG is not universally available. Therefore, we tested the hypothesis that giving pFSH at CIDR removal might improve the pregnancy rate in a CIDR-based, Cosynch protocol in postpartum, suckled Bos taurus beef cows; a secondary objective was to compare pregnancy rates when GnRH v. pLH was used to synchronize wave emergence and ovulation. This work was conducted as two experiments (separate locations). All cows were given a CIDR (containing 1.9 g progesterone; Pfizer Animal Health, Montreal, QC, Canada) on Day 0 (without regard to stage of estrous cycle or cyclicity). On Day 7, CIDRs were removed, all cows were concurrently given 25 mg PGF (Lutalyse; Pfizer Animal Health, Groton, CT, USA), half were given 20 mg pFSH (Folltropin-V; Bioniche Animal Health, Belleville, ON, Canada), and all cows were timed-AI 54 h later (Day 9). In Experiment 1, 240 cows [94 � 10.8 days postpartum; body condition score (BCS: 1 = emaciated, 9 = obese; mean � SD): 5.8 � 0.4] were used; at CIDR insertion and AI, cows were allocated to receive either 100 µg GnRH (n = 160; Cystorelin, Merial Canada Inc., Victoriaville, QC, Canada) or 12.5 mg pLH (n = 80; Lutropin-V, Bioniche Animal Health). In Experiment 2, 109 cows (59.2 � 19.5 days postpartum; BCS: 5.6 � 1.1) were used; all received 100 µg GnRH (Cystorelin) at CIDR insertion and AI. In Experiment 1, three cows that lost their CIDR were excluded; pregnancy rates after timed-AI (logistic regression, backward selection: parity, pFSH, synchronizing treatment, and their interactions) were not different between cows given pFSH v. control cows (64.7 v. 65.2%; P > 0.80), nor between cows given GnRH v. pLH (62.7 v. 69.6%; P = 0.91). However, there was an interaction (P < 0.04) between parity and the synchronizing treatment; in primiparous cows, pregnancy rates were significantly lower in those given GnRH v. pLH (59.3 v. 83.3%). In Experiment 2, pregnancy rates after timed-AI (logistic regression, backward selection: parity, pFSH, and their interaction) were not different between cows given pFSH v. control cows (38.2 v. 42.6%; P > 0.6). In conclusion, our hypothesis was not supported; giving pFSH at CIDR removal did not significantly improve the pregnancy rate in a CIDR-based, Cosynch protocol in postpartum, suckled Bos taurus beef cows.

Forced solitary waves and fronts past submerged obstacles

Herein, an efficient numerical method is presented to describe the flow of a liquid in an open channel with various types of bottom configurations. The method is developed for steady two-dimensional potential free surface flows. The resulting nonlinear problem is solved numerically by boundary integral equation methods. In addition weakly nonlinear solutions are derived. New solutions which complement those of Dias and Vanden-Broeck [J. Fluid Mech. 59, 93-102 (2004)] are presented. Furthermore some solutions for channel flows past dips in the bottom are discussed.

Human immunodeficiency virus (HIV)-2-specific T lymphocyte proliferative responses in HIV-2-infected and in HIV-2-exposed but uninfected individuals in Guinea-Bissau

Human immunodeficiency virus (HIV)-2-specific T lymphocyte proliferative responses were determined in cultures of peripheral blood mononuclear cells from HIV-2-exposed uninfected individuals, HIV-2-infected individuals and HIV-negative controls in Guinea-Bissau. Increased HIV-2-specific T lymphocyte proliferative responses were detected in both groups compared to HIV-negative controls (healthy HIV-uninfected individuals without known exposure to an HIV-infected person); five out of 29 of the HIV-2-exposed uninfected and half (16 of 32) of the HIV-2-infected individuals had stimulation indexes >2, compared to one out of 49 of the HIV-negative controls (P = 0.003 and P < 0.0001, respectively). The exposed uninfected individuals had reactivity to a HIV-2 V3-peptide corresponding to amino acids 311-326 of the envelope glycoprotein, while the HIV-2-infected people reacted mainly to HIV-2 whole viral lysate. Thus, this study demonstrates a high degree of HIV-2-specific T helper cell activity, as measured by lymphocyte proliferation, in HIV-2-exposed uninfected individuals as well as in HIV-2-infected subjects. These immune responses could be important for resistance to the infection and for the control of established infection and, thus, play a role in the lower transmission and progression of HIV-2 compared to HIV-1.

Additive genetic relationships between heifer pregnancy and scrotal circumference in Nellore cattle1

To estimate heritability (h2) for yearling heifer pregnancy and to estimate the genetic correlation between heifer pregnancy and scrotal circumference, 18,145 records of Nellore heifers exposed to breeding at an age of approximately 14 mo and 25,466 records of contemporary young bulls were analyzed. Heifer pregnancy was considered as a categorical trait, with the value 1 (success) assigned to heifers that were pregnant after rectal palpation approximately 60 d after the end of a 90-d breeding season and the value 0 (failure) otherwise. A single-trait animal model for heifer pregnancy and a two-trait animal model including heifer pregnancy and scrotal circumference were used. Contemporary groups were defined in two ways: including (CG2) or not including (CG1) weaning management of the heifer. Heritability estimates obtained by Method R in single-trait analyses were 0.68 +/- 0.09 and 0.61 +/- 0.10 using CG1 and CG2 definitions, respectively. Heritability estimates for two-trait analyses were 0.69 +/- 0.09 (CG1) and 0.63 +/- 0.08 (CG2) for heifer pregnancy and 0.57 +/- 0.03 (both CG) for scrotal circumference. The genetic correlation estimates between the two traits were 0.20 +/- 0.12 (CG1) and 0.20 +/- 0.13 (CG2). Based on the results of this study, EPD for heifer pregnancy can be used to select bulls for the production of precocious daughters and will be more effective than selecting on scrotal circumference EPD in Nellore cattle. However, scrotal circumference can be incorporated in a two-trait analysis to increase the accuracy of prediction for heifer pregnancy EPD for young bulls. Using contemporary group without heifer weaning management gave higher h2 and, for two-trait analysis, converged more quickly.

Genetic evaluation of the probability of pregnancy at 14 months for Nellore heifers

To estimate the heritability for the probability that yearling heifers would become pregnant, we analyzed the records of 11,487 Nellore animals that participated in breeding seasons at three farms in the Brazilian states of São Paulo and Mato Grosso do Sul. All heifers were exposed to a bull at the age of about 14 mo. The probability of pregnancy was analyzed as a categorical trait, with a value of 1 (success) assigned to heifers that were diagnosed pregnant by rectal palpation about 60 d after the end of the breeding season of 90 d and a value of 0 (failure) assigned to those that were not pregnant at that time. The estimate of heritability, obtained by Method R, was 0.57 with standard error of 0.01. The EPD was predicted using a maximum a posteriori threshold method and was expressed as deviations from 50% probability. The range in EPD was -24.50 to 24.55%, with a mean of 0.78% and a SD of 7.46%. We conclude that EPD for probability of pregnancy can be used to select heifers with a higher probability of being fertile. However, it is mainly recommended for the selection of bulls for the production of precocious daughters because the accuracy of prediction is higher for bulls, depending on their number of daughters.

HIV-2 does not protect against HIV-1 infection in a rural community in Guinea-Bissau

OBJECTIVE

To examine the putative protective effect of HIV-2 infection against subsequent HIV-1 infection.

DESIGN

Retrospective analysis of data from two cross-sectional surveys in the same community.

METHODS

Two surveys between 1989 and 1998 in a rural area in northwestern Guinea-Bissau provided data from residents aged 15-59 years. HIV testing was done in the first survey. In the second survey, tests were made for both HIV and syphilis, and data on sociodemographic factors and sexual behaviour, including commercial sex work, were gathered. Qualitative polymerase chain reaction amplification of HIV-1 and HIV-2 viral DNA was performed on serologically dually reactive samples.

RESULTS

Of the 2276 eligible adult villagers initially tested, 60% (1360) provided a second sample. Of 110 HIV-2-infected subjects, 17 became additionally infected with HIV-1 [incidence rate (IR), 26.3/1000 person-years observation]. Of the 1250 HIV-seronegative subjects, 24 became infected with HIV-1 (IR, 2.8/1000 person-years observation). The incidence rate ratio (IRR), comparing the incidence rate in HIV-2-infected people with the rate in HIV-seronegative subjects, was > 1 in all three "risk groups": men, female commercial sex workers, and other women. The overall estimate of the IRR, adjusted for age group and risk group, was 3.24 (confidence interval, 1.5-7.1).

CONCLUSIONS

There was no protective effect of HIV-2 in this population. HIV-2 cannot be regarded as a vaccine, but, instead, may be a risk factor for HIV-1 infection.

Intestinal parasites in HIV-2 associated AIDS cases with chronic diarrhoea in Guinea-Bissau

Previous studies from African countries where HIV-1 infection is prevalent have shown that infections with Cryptosporidium parvum, Isospora belli and microsporidia are frequently associated with chronic diarrhoea in AIDS patients. The information about the occurrence of these parasites in HIV-2 associated AIDS cases with chronic diarrhoea is limited. We have performed a study of stool parasites in patients from Guinea-Bissau, the country with the highest prevalence of HIV-2 in the world. Stool specimens from 52 adult patients with chronic diarrhoea of which 37 were HIV-positive and fulfilling the clinical criteria of AIDS (five HIV-1, 28 HIV-2 and four dually infected with HIV-1 and HIV-2) were screened for parasitic infections. Twenty five percent of the HIV-2 positive patients were infected with C. parvum, 11% with I. belli and 11% with microsporidia, all three parasites were seen only in HIV-positive patients. The three patients with microsporidiosis, all HIV-2 infected, are to our knowledge the first cases reported from Guinea-Bissau. Other stool parasites such as Blastocystis hominis, hookworm and Strongyloides stercoralis were observed both among HIV-positive and HIV-negative patients.

Community-based controlled trial of dietary management of children with persistent diarrhea: sustained beneficial effect on ponderal and linear growth

BACKGROUND

Uncontrolled hospital-based studies in developing countries have reported promising results of dietary rehabilitation of children with persistent diarrhea.

OBJECTIVE

The objective was to determine the immediate and long-term effects of a dietary supplement and micronutrients given to children with persistent diarrhea during the episode and for 1 wk during convalescence.

DESIGN

The study was open, controlled, and community-based and was conducted in a periurban area in Guinea-BISSAU: Children <3 y of age with persistent diarrhea were identified during weekly household visits. The children randomly assigned to the treatment and control groups were examined by a physician and all medical conditions were treated. The children in the treatment group were offered home-based dietary treatment consisting of locally available foods and micronutrient supplements.

RESULTS

There were 141 episodes of persistent diarrhea during the study: 70 in the treatment group (in 58 children) and 71 in the control group (in 62 children). During the intervention period (median: 17 d), weight gain in the treatment group exceeded that of the control group by 61.5 g/wk (95% CI: 49.2, 73.8), whereas there was no significant difference in linear growth on the basis of knee-heel length. At a median follow-up period of 6.6 mo after the intervention was stopped, weight gain in the treatment group exceeded that of the control group by 12.5 g/wk (95% CI: 7.7, 17.3); knee-heel length was 7.5 mm/y (4.8, 10.2) greater and total length was 0.65 cm/y (0.11, 1.19) greater in the treatment group.

CONCLUSION

Therapeutic feeding and micronutrient supplementation had an immediate and sustained beneficial effect on growth in children with persistent diarrhea.

Measles antibody responses after early two dose trials in Guinea-Bissau with Edmonston-Zagreb and Schwarz standard-titre measles vaccine: better antibody increase from booster dose of the Edmonston-Zagreb vaccine

In Guinea-Bissau, children were randomised at 6 months of age to receive either two doses of standard-titre measles vaccine at 6 and 9 months of age or an inactivated polio vaccine at 6 months and standard-titre measles vaccine at 9 months of age. During the first 5 months, children received Edmonston-Zagreb (EZ) vaccine and during the following 11 months, the Schwarz (SW) vaccine. Five percent of the mothers, 74% of children at 6 months of age, and 92% of unvaccinated children at 9 months of age had unprotective levels (<125 mIU/ml) of measles antibodies. Among children receiving EZ vaccine, 1% were unprotected at 18 months of age after either two (3/240) or one (3/211) doses of vaccine, the geometric mean measles antibody titre (GMT) being approximately 1550 mIU/ml in both groups. Among those receiving SW vaccine 9% (34/365) and 3% (9/310) were unprotected at 18 months of age in the two-dose and the one-dose groups (RR = 3.21 (95% confidence interval (CI) 1.56-6.58)), respectively. The GMT was higher after one dose of SW vaccine at 9 months of age (2491 mIU/ml) than after two doses of SW vaccine (1125 mIU) (P < 0.001). In the EZ vaccine group, there was no significant difference in antibody level for children vaccinated in the presence of high or low levels of maternal antibodies, whereas there was a marked difference in the SW group. The second EZ vaccine induced a significant antibody increase between 9 months of age (1191 mIU) and 18 months of age (1602 mIU, P=0.011), whereas antibody levels tended to decline from 9 months (1243 mIU) to 18 months of age (998 mIU, P = 0.124) after the second dose of SW vaccine. Conclusively, after two doses of EZ measles vaccine more children were protected at 18 months of age than after two doses of SW. One dose of SW provided the highest antibody response, but a higher proportion of unprotected than one or two doses of EZ. The EZ vaccine was less sensitive to maternal antibodies, and able to increase the antibody response by revaccination, while the second SW vaccine resulted in an unchanged or lower antibody response.

Prevalences of HTLV-1 infection and associated risk determinants in an urban population in Guinea-Bissau, West Africa

OBJECTIVE

To assess the prevalence and modes of transmission of HTLV-1 infection in an adult population in Bissau, and to evaluate possible interactions between the pattern of spread of HTLV-1 and HIV-1/HIV-2.

DESIGN AND METHODS

Univariate and multivariate analyses were used to evaluate gender-and age-specific HTLV-1 prevalences as well as associated risk determinants in an adult population based on a serosurvey comprising 2127 individuals from 304 randomly selected houses in Bissau.

RESULTS

Using stringent Western blot criteria, the overall seroprevalence of HTLV-1 was 3.6%, 2.2% among men and 4.7% among women, respectively. One individual was seropositive to HTLV-2. The prevalence of HTLV-1, which increased with age in both genders, however more markedly among women, was >4 times higher (9.4%) among older individuals (>44 years of age) than among younger individuals (2.4%). Blood transfusion and HIV-2 seropositivity were independently associated with HTLV-1 seropositivity in men. Among women, both HIV-2 seropositivity and HIV-1 seropositivity were significant risk determinants. Having had sexual partners was associated with a fivefold increased risk among women but did not reach significance.

CONCLUSION

The adult population of Guinea-Bissau has a higher prevalence of HTLV-1 than reported from most other countries in West Africa. The gender-and age-specific pattern of spread of HTLV-1 closely resembles that observed for HIV-2, another retrovirus prevalent to the region. The close correlation between HTLV-1 and HIV-2 most likely reflects the shared risk factors related to sexual behavior. The implication of the high percentage of double infections in this population needs to be determined.

Class 1 integron-borne, multiple-antibiotic resistance encoded by a 150-kilobase conjugative plasmid in epidemic vibrio cholerae O1 strains isolated in Guinea-Bissau

In the 1996-1997 cholera epidemic in Guinea-Bissau, surveillance for antimicrobial resistance showed the emergence of a multidrug-resistant strain of Vibrio cholerae O1 during the course of the epidemic. The strain was resistant to ampicillin, erythromycin, tetracycline, furazolidone, aminoglycosides, trimethoprim, and sulfamethoxazole. Concomitant with the emergence of this strain, we observed a resurgence in the number of registered cholera cases as well as an increase in the case fatality rate from 1.0% before the emergence of the multiple-drug-resistant strain to 5.3% after the emergence of the strain. Our study shows that the strain contained a 150-kb conjugative multiple-antibiotic resistance plasmid with class 1 integron-borne gene cassettes encoding resistance to trimethoprim (dhfrXII) and aminoglycosides [ant(3")-1a]). The finding of transferable resistance to almost all of the antibiotics commonly used to treat cholera is of great public health concern. Studies should be carried out to determine to what extent the strain or its resistance genes have been spread to other areas where cholera is endemic.

Risk factors for HIV-2 seropositivity among older people in Guinea-Bissau. A search for the early history of HIV-2 infection

Because the seroprevalence of HIV-2 has been shown to be high in older age groups, we conducted a survey of all persons aged 50 years or over in two districts in Bissau, investigating the presence of HIV antibodies and possible risk factors for HIV infection with a particular emphasis on age, the impact of the war of independence (1963-74), traditional marital and extramarital sex patterns, blood contact and contact with monkeys. In 670 participants, the HIV-2 prevalence was 14.3%; 16.1% in women and 12.3% in men. The HIV-1 prevalence was only 0.5% (3/670). The HIV-2 prevalence peaked for men in the 60-69 years age group, and for women in the 50-59 years age group, declining markedly in the following age group for both men and women (OR = 0.09 (0.01-0.51), OR = 0.37 (0.15-0.82), respectively). This pattern could be due to differential mortality for HIV-2 infected individuals or to a cohort effect for a generation who were sexually active at the time of the war of independence in the 1960s and early 1970s in Bissau. Supporting the link with the colonial army, women who had had sex with a white man had a higher seroprevalence (OR = 3.63 (1.12-11.24)). The ethnic group indigenous to Bissau city had a much lower prevalence, but demographic and cultural risk factors such as marital status, religion, education and having lived outside Bissau were not associated with HIV-2. In the multivariate analyses for women, variables related to extramarital sex or prostitution (having sex with a white man, having lived in Senegal, not living with husband, and not marrying first sexual partner) were associated with higher risk. For men, previous spouses who had died or had divorced were associated with higher prevalence. Having married the first sexual partner was protective against HIV-2 infection for both men (OR = 0.29 (0.09-0.76)) and women (OR = 0.19 (0.04-1.00)). Hospitalizations, possibly due to transfusions, tended to be associated with higher risk, but only for women (OR = 1.83 (0.97-3.48)). The focus of the HIV-2 epidemic in Guinea-Bissau is likely to be endogenous, and the war of independence and the colonial army with its associated prostitution may have played an important part in propagating the virus.

Three-year follow-up of patients with pulmonary tuberculosis in Guinea-Bissau, West Africa

SETTING

Raoul Follereau Hospital, Bissau, Guinea-Bissau.

OBJECTIVE

To study the long-term outcome of patients with bacteriologically verified tuberculosis (TB), with or without human immunodeficiency virus (HIV) co-infection.

DESIGN

Sputum samples were collected from all patients referred to the hospital with clinical symptoms of pulmonary tuberculosis. Direct microscopy and culture was performed at the Health Laboratory. Patients with a culture positive for Mycobacterium tuberculosis were followed for 3 years, and underlying factors were analysed regarding the outcome of treatment. A group of sex and age-matched HIV-negative individuals was used as controls.

RESULTS

Of 206 bacteriologically verified pulmonary TB patients, 168 were followed up. Antibodies to HIV-2 were found in 33 patients (19.6%); eight patients (4.8%) had antibodies to HIV-1 or showed dual reactivity. Of 149 patients discharged to follow ambulatory treatment, the survival rate of HIV-2-positive patients was 42.3% (11/26) and for HIV-negative patients it was 81.9% (95/116). The difference in survival between HIV-2-positive and HIV-negative patients was highly significant (P < 0.00001). HIV-negative TB patients had a significantly higher mortality than their controls (mortality ratio 3.75, 95% confidence interval 1.58-8.90). Most patients who survived, regardless of HIV status, also became free from symptoms compatible wtih pulmonary TB.

CONCLUSION

Although the mortality rate among HIV-positive TB patients was very much higher than among HIV-negative patients, there are weighty arguments for active contact tracing and effective treatment of all TB patients.