Declining antibody affinity over time after human vaccination with a Plasmodium falciparum merozoite vaccine candidate.

Maintaining high affinity antibodies after vaccination may be important for long-lasting immunity to malaria, but data on induction and kinetics of affinity is lacking. In a Phase 1 malaria vaccine trial, antibody affinity increased following a second vaccination but declined substantially over 12-months, suggesting poor maintenance of high affinity antibodies.

Head-to-head comparison of two loop-mediated isothermal amplification (LAMP) kits for diagnosis of malaria in a non-endemic setting.

BACKGROUND: Light microscopy and rapid diagnostic tests (RDT) have long been the recommended diagnostic methods for malaria. However, in recent years, loop-mediated isothermal amplification (LAMP) techniques have been shown to offer superior performance, in particular concerning low-grade parasitaemia, by delivering higher sensitivity and specificity with low laboratory capacity requirements in little more than an hour. In this study, the diagnostic performance of two LAMP kits were assessed head-to-head, compared to highly sensitive quantitative real time PCR (qPCR), in a non-endemic setting. METHODS: In this retrospective validation study two LAMP kits; Alethia® Illumigene Malaria kit and HumaTurb Loopamp™ Malaria Pan Detection (PDT) kit, were evaluated head-to-head for detection of Plasmodium-DNA in 133 biobanked blood samples from suspected malaria cases at the Clinical Microbiology Laboratory of Region Skåne, Sweden to determine their diagnostic performance compared to qPCR. RESULTS: Of the 133 samples tested, qPCR detected Plasmodium DNA in 41 samples (defined as true positives), and the two LAMP methods detected 41 and 37 of those, respectively. The results from the HumaTurb Loopamp™ Malaria PDT kit were in complete congruence with the qPCR, with a sensitivity of 100% (95% CI 91.40-100%) and specificity of 100% (95% CI 96.07-100%). The Alethia® Illumigene Malaria kit had a sensitivity of 90.24% (95% CI 76.87-97.28) and a specificity of 95.65% (95% CI 89.24-98.80) as compared to qPCR. CONCLUSIONS: This head-to-head comparison showed higher performance indicators of the HumaTurb Loopamp™ Malaria PDT kit compared to the Alethia® illumigene Malaria kit for detection of malaria.

Platelets inhibit erythrocyte invasion by Plasmodium falciparum at physiological platelet:erythrocyte ratios.

OBJECTIVE: To evaluate the effect of platelet:erythrocyte (P:E) ratios on Plasmodium falciparum erythrocyte invasion. BACKGROUND: Recent reports have shown that platelets are directly involved in the immune response towards P. falciparum during erythrocyte invasion. However, the literature both supports and conflicts with a role for platelets in limiting invasion. Also, the effect of platelet numbers on invasion (parasitemia) has not been thoroughly investigated. METHODS/MATERIALS: The P. falciparum strains FCR3S1.2 and W2mef were cultured with group O erythrocytes. The cultures were synchronised and supplemented with pooled platelets at P:E ratios ranging from 1:100 to 1:2. Parasitemia was measured at 40 h by flow cytometry and by microscopy of blood smears. RESULTS: A linear relationship was observed between reduced invasion and increased platelet numbers at P:E ratios ranging from 1:100 to 1:20. However, this effect was reversed at lower ratios (1:10-1:2). Microscopic evaluation revealed aggregation and attachment of platelets to erythrocytes, but not specifically to parasitised erythrocytes. CONCLUSION: We have shown that under physiological P:E ratios (approx. 1:10-1:40), platelets inhibited P. falciparum invasion in a dose-dependent manner. At ratios of 1:10 and below, platelets did not further increase the inhibitory effect and, although the trend was reversed, inhibition was still maintained.

Prevalence and risk factors for transactional sex among Swedish-born and foreign-born MSM in Sweden.

BACKGROUND: Little is known about transactional sex (TS) (selling and buying sex) among men who have sex with men (MSM) in Sweden, especially among foreign-born MSM. This study aims to assess the prevalence and risk factors of TS (ever and in the previous five years) among MSM living in Sweden and to determine if there is a difference between Swedish-born MSM and foreign-born MSM. METHODS: Swedish data from a multicountry online banner survey (EMIS-2017) was used (n = 4443). Multivariable regression analysis was applied to analyse the data. RESULTS: The prevalence of ever-selling sex among all MSM participants was 13.2% and 5.9% in the previous five years. Selling sex ever and in the previous five years was higher among foreign-born MSM (16% and 8.4%, respectively) than Swedish-born MSM (12.7% and 5.4%, respectively). Among all participants, younger age (aOR:3.19, 95% CI:1.57-6.45) and really struggling to live on current income (aOR:3.37, 95% CI:2.29-4.96) increased the odds of selling sex. Being foreign-born MSM (aOR:1.33, 95% CI:1.02-1.73) and having had sex with a woman in the previous 12 months increased the odds of selling sex (aOR:1.44, 95% CI:1.00-2.07). The prevalence of ever buying sex among MSM participants in Sweden was 10.8% and 6.7% in the previous five years, with the same trend among foreign-born MSM (11.6% and 6.9%, respectively) and Swedish-born MSM (10.7% and 6.6%, respectively). Higher education and not having a current partner increased the odds of buying sex. Younger age was protective for buying sex (aOR:0.05, 95% CI:0.02-0.14). Among the foreign-born MSM, the length of stay in Sweden decreased the odds of buying sex (aOR: 0.98, 95% CI: 0.96-0.99). CONCLUSIONS: The comparatively high prevalence of TS among MSM participants in Sweden, where buying sex is illegal, with a higher prevalence among foreign-born MSM participants, calls for sexual and reproductive health and rights interventions in this population. Increased attention, including HIV prevention programming and education, should be aimed at younger MSM, MSM struggling with their current income, and foreign-born MSM, as they are more likely to report selling sex.

Osteopontin and malaria: no direct effect on parasite growth, but correlation with P. falciparum-specific B cells and BAFF in a malaria endemic area.

BACKGROUND: The dysregulation of B cell activation is prevalent during naturally acquired immunity against malaria. Osteopontin (OPN), a protein produced by various cells including B cells, is a phosphorylated glycoprotein that participates in immune regulation and has been suggested to be involved in the immune response against malaria. Here we studied the longitudinal concentrations of OPN in infants and their mothers living in Uganda, and how OPN concentrations correlated with B cell subsets specific for P. falciparum and B cell activating factor (BAFF). We also investigated the direct effect of OPN on P. falciparum in vitro. RESULTS: The OPN concentration was higher in the infants compared to the mothers, and OPN concentration in infants decreased from birth until 9 months. OPN concentration in infants during 9 months were independent of OPN concentrations in corresponding mothers. OPN concentrations in infants were inversely correlated with total atypical memory B cells (MBCs) as well as P. falciparum-specific atypical MBCs. There was a positive correlation between OPN and BAFF concentrations in both mothers and infants. When OPN was added to P. falciparum cultured in vitro, parasitemia was unaffected regardless of OPN concentration. CONCLUSIONS: The concentrations of OPN in infants were higher and independent of the OPN concentrations in corresponding mothers. In vitro, OPN does not have a direct effect on P. falciparum growth. Our correlation analysis results suggest that OPN could have a role in the B cell immune response and acquisition of natural immunity against malaria.

Direct contact between Plasmodium falciparum and human B-cells in a novel co-culture increases parasite growth and affects B-cell growth.

BACKGROUND: Plasmodium falciparum parasites cause malaria and co-exist in humans together with B-cells for long periods of time. Immunity is only achieved after repeated exposure. There has been a lack of methods to mimic the in vivo co-occurrence, where cells and parasites can be grown together for many days, and it has been difficult with long time in vitro studies. METHODS AND RESULTS: A new method for growing P. falciparum in 5% CO2 with a specially formulated culture medium is described. This knowledge was used to establish the co-culture of live P. falciparum together with human B-cells in vitro for 10 days. The presence of B-cells clearly enhanced parasite growth, but less so when Transwell inserts were used (not allowing passage of cells or merozoites), showing that direct contact is advantageous. B-cells also proliferated more in presence of parasites. Symbiotic parasitic growth was verified using CESS cell-line and it showed similar results, indicating that B-cells are indeed the cells responsible for the effect. In malaria endemic areas, people often have increased levels of atypical memory B-cells in the blood, and in this assay it was demonstrated that when parasites were present there was an increase in the proportion of CD19 + CD20 + CD27 - FCRL4 + B-cells, and a contraction of classical memory B-cells. This effect was most clearly seen when direct contact between B-cells and parasites was allowed. CONCLUSIONS: These results demonstrate that P. falciparum and B-cells undoubtedly can affect each other when allowed to multiply together, which is valuable information for future vaccine studies.

Sex, drugs and techno - a qualitative study on finding the balance between risk, safety and pleasure among men who have sex with men engaging in recreational and sexualised drug use.

BACKGROUND: Recreational and sexual drug use among men who have sex with men may result in increased risk of poor health. The aim of this study was to better understand drug use and harm reduction techniques among Swedish men who have sex with men traveling to Berlin in order to improve the health of this population and inform public health strategies. METHODS: A qualitative study based on semi-structured interviews with 15 Swedish men aged 23-44 with experience of drug use were recruited through network sampling. Interviews were conducted in Stockholm and Berlin and analysed using content analysis. The interview guide included questions on drug use, context, health and safety. RESULTS: The participants engaged in drug use in both settings and in various contexts. Participants saw themselves as capable of finding a balance between pleasure, safety and risk with the aim to maximize positive effects while minimizing negative ones. The different risks of drug use were known, and participants relied on knowledge, harm reduction strategies and self-defined rules of intake to stay safe and healthy in a broad sense, both short term (i.e. during each session) and long term. Choice of drug and, frequency of intake, multi-use, risk of overdose, risk of HIV, purpose and context of use, how often, etc. were all part of the overall strategy. Knowledge of these methods was spread within the community and on-line rather than from counsellors or other health care providers. However, it did not always translate perfectly into practice and some had experienced overdoses and problematic use. CONCLUSIONS: The findings of this study point to the need for increased adoption of harm reduction techniques in this population focusing on mitigating harm and prevention of risk of problematic use or starting injection drugs. Existing traditional services require adaptations to become more accessible and acceptable to sub-groups of drug users, including low-threshold services providing non-judgemental, evidence-based information. This will require funding of alternative providers such as STI/HIV clinics, among others, and health care providers to increase adoption of prevention strategies, specifically pre-exposure prophylaxis for HIV.

Structured Observation of Motor Performance in Infants: Level and quality associated with later motor development.

AIM: The aim of this study was to investigate the level of motor development and the quality of motor performance during the first 10 months in relation to the Bayley Scales of Infant Development-third edition (Bayley-III) motor index at 2.5 years. METHODS: Children born very preterm from a population-based study (n = 113) were assessed with the Structured Observation of Motor Performance in Infants (SOMP-I) at 2, 4, 6 and 10 months corrected age and the Bayley-III motor index at 2.5 years corrected age (n = 98). Logistic regressions were performed to investigate the independent association of each SOMP-I domain to Bayley-III motor index. RESULTS: There were significant associations between the SOMP-I-scores and Bayley-III motor index per every assessment age. At 4 months, both level and quality were independently associated with a later motor outcome, OR for level was 1.26 (95% CI = 1.08-1.50, P = .002) and for quality, 0.75 (95% CI = 0.63-0.90, P = .002). Quality was independently associated with the Bayley-III motor index at 6 and 10 months: OR 0.080 (95% CI = 0.67-0.95 P = .010) and 0.79 (95% CI = 0.64-0.97, P = .026). CONCLUSION: Both SOMP-I domains, level and quality, are markers to identify motor problems early. Quality became more important with age.

Factors associated with condom use and HIV testing among young men who have sex with men: a cross-sectional survey in a random online sample in Sweden.

OBJECTIVES: The objectives are to analyse social determinants of sexual health behaviour (condom use and HIV testing) among young, internet-active, cis men who have sex with men (MSM) in a high-income country. The aspects of sexual health behaviour analysed here are condomless anal intercourse with one or more new or casual partner(s), condomless anal intercourse during the most recent sex with a man and HIV testing. METHODS: A randomised sample of men active on Sweden's main online community for Lesbian, Gay, Bisexual and Trans people responded to an online survey (response rate 19%). A subsample of young people, aged 15-29, was analysed (effective sample 597-669) using multivariable logistic regression with respect to factors associated with condomless anal intercourse with one or more new or casual partner(s), condomless anal intercourse at most recent sex and not having had a test for HIV. RESULTS: Low education, being single and living in a metropolitan area were found to be independently associated with condomless anal intercourse with new or casual partner(s). Sex with a steady partner was associated with condomless anal intercourse during the most recent sex. Knowledge of where to get tested, high education, being born outside Sweden and condomless anal intercourse with new or casual sex partner(s) were independently associated with having been tested for HIV. CONCLUSIONS: The factors associated with sexual health behaviour among young MSM are complex, and preventive messages need to be tailored accordingly.

Development of Plasmodium falciparum specific naïve, atypical, memory and plasma B cells during infancy and in adults in an endemic area.

BACKGROUND: B-cells are essential in immunity against malaria, but which sub-sets of B-cells specifically recognize Plasmodium falciparum and when they appear is still largely unknown. RESULTS: Using the flow cytometry technique for detection of P. falciparum specific (Pf+) B-cells, this study for the first time measured the development of Pf+ B cell (CD19+) phenotypes in Ugandan babies from birth up to nine months, and in their mothers. The babies showed increases in Pf+ IgG memory B-cells (MBCs), atypical MBCs, and plasma cells/blasts over time, but the proportion of these cells were still lower than in the mothers who displayed stable levels (5, 18, and 3%, respectively). Pf+ non-IgG+ MBCs and naïve B-cells binding to P. falciparum antigens were higher in the babies compared to the mothers (12 and 50%). In ELISA there was an increase in IgG and IgM antibodies over time in babies, and stable levels in mothers. At baby delivery, multigravidae mothers had a higher proportion of Pf+ IgG MBCs and less Pf+ naïve B-cells than primigravidae mothers. CONCLUSIONS: In newborns, naïve B-cells are a major player in recognizing P. falciparum. In adults, the high proportion of Pf+ atypical MBCs suggests a major role for these cells. Both in infants and adults, non-IgG+ MBCs were higher than IgG MBCs, indicating that these cells deserve more focus in future.

HIV testing and prevention among foreign-born Men Who have Sex with Men: an online survey from Sweden.

BACKGROUND: There is an increasing trend toward international migration worldwide. With it comes a challenge for public health and public funded health care systems to meet the migrating population's health needs. Men who have sex with men are a key population for HIV, contributing an estimated 42% of new HIV cases in Europe in 2013. HIV monitoring data suggest that foreign-born MSM are not only exposed to a high risk of HIV before migration but also while living in Sweden. The aim of this study is to examine HIV testing prevalence and uptake of HIV prevention interventions among foreign-born MSM living in Sweden. METHODS: A web survey available in English and Swedish was conducted from October 1 to October 30, 2013 via a Scandinavian Web community for Lesbian, Gay, Bisexual, Transgender and Intergender people. The web survey included modules on sociodemographics, condom use, sexual risk behaviour and HIV/STI testing experience. 244 eligible MSM participants born abroad and living in Sweden participated in the study. Descriptive and inferential analysis was performed. RESULTS: Half of the foreign-born MSM participants in this study had been tested for HIV during the last 12 months. Participants who had lived in Sweden less than or equal to 5 years were more likely to have been tested for HIV during the last 12 months. Having talked about HIV/STI with a prevention worker during the past year was associated with having been tested for HIV. Requested services among the majority of participants were HIV rapid test, anonymous HIV testing, HIV/STI testing outside of the health care setting and MSM-friendly clinics. CONCLUSION: Efforts are needed to promote HIV testing among foreign-born MSM. Peer outreach, individual and group counselling may be preferred interventions to do so. In addition, it is critically important to increase HIV testing among foreign-born MSM who have lived in Sweden for more than five years. Further research should explore if scale up of implementation of requested services may increase frequency of HIV testing and detection of new cases linked to treatment among foreign-born MSM living in Sweden.

The Structured Observation of Motor Performance in Infants has convergent and discriminant validity in preterm and term infants.

AIM: Methods are needed to evaluate the level of early motor development and quality of motor performance in infants. We examined the convergent and discriminant validity of the Structured Observation of Motor Performance in Infants (SOMP-I) for evaluating the level of motor development and quality of motor performance in preterm and term infants. METHODS: A regional cohort of 111 preterm infants with a gestational age of <32 weeks and 72 healthy term born infants were assessed with the SOMP-I, at two, four, six and 10 months of corrected age. Convergent validity was analysed with a mixed model analysis of the motor performance over time. Discriminant validity was analysed with the Mann-Whitney U-test in groups with different neonatal characteristics. RESULTS: Convergent validity was supported, as the level of motor development increased with age and the quality of motor performance improved over time. The method discriminated for both level and quality between the preterm and the term infants. The preterm infants demonstrated different quality deficits regardless of the level of motor development. CONCLUSION: Convergent validity and discriminant validity of the SOMP-I were supported in preterm and term infants and facilitates early identification of infants with atypical motor development.

Experimentals, bottoms, risk-reducers and clubbers: exploring diverse sexual practice in an Internet-active high-risk behaviour group of men who have sex with men in Sweden.

This study aimed to identify sub-groups of men who have sex with men at high risk of HIV infection. Data from the Swedish MSM2013 survey were analysed with a focus on respondents (n = 714) who reported having had unprotected anal intercourse with male casual partner(s) in the past 12 months. Weighted Latent Class Analysis with covariates and distal outcomes was conducted to identify sub-groups of men sharing the same sexual practice characteristics. Four latent classes emerged: experimentals, bottoms, risk-reducers and clubbers. Experimentals appeared to differ most from the other classes. They had extensive experience of barebacking, the use of poppers and fisting. Higher number of casual male sex partners and reporting having HIV were predictors for belonging to experimentals. No evidence for an association between self-rated HIV prevention knowledge and taking less part in risky practices was found. Hence, knowledge-intensive interventions may not be the best fit for reducing HIV transmission. This diversity of men based on similar sexual practice patterns should be taken into account when designing future HIV prevention interventions.

Motivators and barriers for HIV testing among men who have sex with men in Sweden.

AIMS AND OBJECTIVES: To explore motivators and barriers to HIV testing and to assess the factors associated with testing among men who have sex with men. BACKGROUND: Previous research has considered fear, worries and structural barriers as hindrances to HIV testing among men who have sex with men. However, few studies have included assessments of actual HIV testing when exploring barriers or motivators for such testing. DESIGN: The design of the study was a stratified cross-sectional online survey (n = 2373). METHOD: Factor analysis was conducted to analyse the barriers and motivators for HIV testing. Logistic regression analysis was conducted to assess predictors for HIV testing. RESULTS: Many men who have sex with men test for HIV regularly, and specific reasons for testing were having unprotected sex or starting/ending a relationship. A lack of awareness and a perception of being at low risk for exposure were common reasons for never being tested. Fear and anxiety as well as barriers related to the use of test services remain important hindrances for testing. Predictors associated with having been tested within the past 12 months were: younger age (15-25 years old compared with 47+); knowledge on where to take an HIV test on short notice as well as having talked with a counsellor, having received condoms for free, or having had unprotected anal intercourse with casual partners within the last 12 months. CONCLUSION: Easily accessible test services offering testing and counselling on short notice should be available for all men who have sex with men. Outreach activities, distribution of free condoms and testing at venues where men who have sex with men meet are important prevention add-ons that can contribute to increased awareness about HIV and testing. RELEVANCE TO CLINICAL PRACTICE: Test services must ensure confidentiality and health care professionals who meet men who have sex with men for testing need competency with regards to men who have sex with men sexual health needs.

Differences in affinity of monoclonal and naturally acquired polyclonal antibodies against Plasmodium falciparum merozoite antigens.

BACKGROUND: Malaria is a major global cause of deaths and a vaccine is urgently needed. RESULTS: We have employed the P. falciparum merozoite antigens MSP2-3D7/FC27 and AMA1, used them in ELISA, and coupled them in different ways using surface plasmon resonance (SPR) and estimated affinity (measured as kd) of monoclonal as well as naturally-acquired polyclonal antibodies in human plasma. There were major differences in kd depending on how the antigens were immobilized and where the His-tag was placed. For AMA1 we could see correlations with invasion inhibition. Using different immobilizations of proteins in SPR, we could see only moderate correlations with levels of antibodies in ELISA, indicating that in ELISA the proteins were not uniformly bound and that antibodies with many specificities exist in natural immunisation. The correlations between ELISA and SPR were enhanced when only parasite positive samples were included, which may indicate that high affinity antibodies are difficult to maintain over long periods of time. We found higher kd values for MSP2 (indicating lower affinity) compared to AMA1, which might be partly explained by MSP2 being an intrinsically disordered protein, while AMA1 is globular. CONCLUSIONS: For future vaccine studies and for understanding immunity, it is important to consider how to present proteins to the immune system to achieve highest antibody affinities.

Novel flow cytometry technique for detection of Plasmodium falciparum specific B-cells in humans: increased levels of specific B-cells in ongoing infection.

BACKGROUND: Malaria caused by Plasmodium falciparum is still a major health threat in endemic areas especially for children below 5 years of age. While it is recognized that antibody immunity plays an important role in controlling the disease, knowledge of the mechanisms of sustenance and natural boosting of immunity is very limited. Before, it has not been possible to investigate malaria specific B-cells directly in flow cytometry, making it difficult to know how much of a B cell response is due to malaria, or how much is due to other immunological stimulators. METHODS: This study developed a technique using quantum dots and schizont extract made from ghosts of infected erythrocytes, to be able to investigate P. falciparum specific B-cells, something that has never been done before. RESULTS: Major differences in P. falciparum specific B-cells were found between samples from immune (22.3 %) and non-immune (1.7 %) individuals. Samples from parasite positive individuals had the highest proportions of specific B-cells (27.9 %). CONCLUSION: The study showed increased levels of P. falciparum-specific B-cells in immune individuals, with the highest levels in active malaria infections, using a new technique that opens up new possibilities to study how these cells are sustained in vivo after natural infections. It will also be useful in vaccine studies.

Erythrocyte-binding antigens of Plasmodium falciparum are targets of human inhibitory antibodies and function to evade naturally acquired immunity.

Abs that inhibit Plasmodium falciparum invasion of erythrocytes form an important component of human immunity against malaria, but key target Ags are largely unknown. Phenotypic variation by P. falciparum mediates the evasion of inhibitory Abs, contributing to the capacity of P. falciparum to cause repeat and chronic infections. However, Ags involved in mediating immune evasion have not been defined, and studies of the function of human Abs are limited. In this study, we used novel approaches to determine the importance of P. falciparum erythrocyte-binding Ags (EBAs), which are important invasion ligands, as targets of human invasion-inhibitory Abs and define their role in contributing to immune evasion through variation in function. We evaluated the invasion-inhibitory activity of acquired Abs from malaria-exposed children and adults from Kenya, using P. falciparum with disruption of genes encoding EBA140, EBA175, and EBA181, either individually or combined as EBA140/EBA175 or EBA175/EBA181 double knockouts. Our findings provide important new evidence that variation in the expression and function of the EBAs plays an important role in evasion of acquired Abs and that a substantial amount of phenotypic diversity results from variation in expression of different EBAs that contributes to immune evasion by P. falciparum. All three EBAs were identified as important targets of naturally acquired inhibitory Abs demonstrated by differential inhibition of parental parasites greater than EBA knockout lines. This knowledge will help to advance malaria vaccine development and suggests that multiple invasion ligands need to be targeted to overcome the capacity of P. falciparum for immune evasion.

Subclass responses and their half-lives for antibodies against EBA175 and PfRh2 in naturally acquired immunity against Plasmodium falciparum malaria.

BACKGROUND: Plasmodium falciparum EBA175 and PfRh2 belong to two main families involved in parasite invasion, and both are potential vaccine candidates. Current knowledge is limited regarding which target antigens and subclasses of antibodies are actually important for protection, and how naturally acquired immunity is achieved. METHODS: Repeated blood samples were collected from individuals in Nigeria over a period of almost one year. ELISA was used to analyse subclasses of IgG responses. RESULTS: For both EBA175 (region III-V) and (a fragment of) PfRh2, the dominant antibody responses consisted of IgG1 and IgG3 followed by IgG2, while for PfRh2 there was also a relatively prominent response for IgG4. High levels of IgG1, IgG2 and IgG3 for EBA175 and total IgG for PfRh2 correlated significantly with a lower parasitaemia during the study period. Children with HbAS had higher levels of some subclasses compared to children with HbAA, while in adults the pattern was the opposite. The half-lives of IgG2 and IgG4 against EBA175 were clearly shorter than those for IgG1 and IgG3. CONCLUSION: EBA175 and PfRh2 are potential targets for protective antibodies since both correlated with lower parasitaemia. The shorter half-lives for IgG2 and IgG4 might explain why these subclasses are often considered less important in protection against malaria. Triggering the right subclass responses could be of critical importance in a successful vaccine. Further studies are needed to evaluate the role of haemoglobin polymorphisms and their malaria protective effects in this process.

Strategies in health-promoting dialogues--primary healthcare nurses' perspectives--a qualitative study.

AIM AND OBJECTIVES: The aim of this study was to describe dialogic strategies about health and lifestyle used by primary healthcare nurses (PHNs) in the Västerbotten Intervention Programme (VIP) in Sweden. BACKGROUND: The VIP offers all citizens aged 40, 50 and 60 in Västerbotten County an individual health check-up followed by a health-promoting dialogue with a specialist PHN. Inconsistencies in previous reports of the effects of lifestyle counselling and health promotion suggest that it is important to study dialogues about health and lifestyle to understand health-promoting strategies and to highlight aspects important to improving their effects. METHOD: In 2010, we conducted in-depth interviews with ten experienced PHNs working with the VIP at eight healthcare centres in Västerbotten County, Sweden. Qualitative content analysis was used to illuminate the nurses' strategies in health-promoting dialogues. The Regional Ethics Board (Dno 06-126M) approved the study. RESULTS: The PHNs used various strategies in dialogues about health and lifestyle that fell under the five themes 'Guiding patients vs. pressuring them; Adjusting to patients vs. directing the conversation; Inspiring confidence vs. instilling fear; Motivating and supporting patients vs. demanding responsibility; and lastly, Introducing emotionally charged subjects or avoiding them'. CONCLUSIONS: The results of this study may add knowledge about the difficulties and opportunities in health counselling. In the discussion, we suggest professional reflection as a means to increase knowledge and awareness about the self and context in the process of health counselling.