Perceptions and attitudes toward COVID-19 vaccination among health professional students in Australia: a qualitative study

Using two qualitative data sources: free-text responses to an open-ended question of an online survey and subsequent interviews and focus groups, we explored perceptions and attitudes toward COVID-19 vaccination among health professional students enrolled in Australian universities during the pandemic with data collected from October 2021 to April 2022. Students provided free-text responses to the open-ended question (n = 313) in the online survey and participated in interviews or focus groups (n = 17). Data analysis revealed three themes, including perceptions of COVID-19 seriousness and the risk of contracting the virus, information dissemination, and attitudes toward the vaccine mandate. The study identified evolving perceptions of COVID-19 seriousness among Australian health professional students and their sentiments toward the vaccine mandate. There is a need to ensure the quality of information dissemination related to the vaccine mandate. This may not only support students' uptake of mandatory vaccination but also provide a means for them to address vaccination with healthcare consumers and patients.

Investigating socio-ecological factors influencing implementation of tuberculosis infection prevention and control in rural Papua New Guinea

BACKGROUND

Tuberculosis (TB) is a highly transmissible infectious disease killing millions of people yearly, particularly in low-income countries. TB is most likely to be transmitted in healthcare settings with poor infection control practices. Implementing TB infection prevention and control (TB-IPC) is pivotal to preventing TB transmission in healthcare settings. This study investigated diverse stakeholders' perspectives relating to barriers and strategies for TB-IPC in rural hospitals in Papua New Guinea.

METHODS

Multiple qualitative case studies were conducted with 32 key stakeholders with experience in TB services. Data collection drew on three primary sources to triangulate data: semi-structured interviews, document reviews and field notes. The data were analyzed using hybrid deductive-inductive thematic analysis.

RESULTS

Our results reveal that key stakeholders perceive multiple interdependent factors that affect TB-IPC practice. The key emerging themes include strategic planning for and prioritizing TB-IPC guidelines; governance, leadership and accountability at the provincial level; community attitudes towards TB control; institutional capacity to deliver TB care, healthcare workers' safety, and long-term partnership and integration of TB-IPC programmes into the broad IPC programme.

CONCLUSIONS

The evidence suggests that a multi-perspective approach is crucial for TB-IPC guidelines in healthcare institutions. Interventions focusing on addressing health systems strengthening may improve the implementation of TB-IPC guidelines.

Infection prevention and control continuous education and training in pre-registration nursing programmes

BACKGROUND

Infection prevention and control (IPC) education and training in pre-registration nursing programmes are imperative in developing student nurses' clinical aptitudes. The IPC core competencies must be consistent amongst student nurses across different settings, asserting the need for education and training providers to respond. Continuous education and training can improve IPC core competencies through enhanced knowledge, compliance, and attitude in the academic and clinical contexts, impacting future nursing practice and patient safety.

OBJECTIVE

This integrative review critically examines the reported IPC core competencies in pre-registration nursing programmes to contribute to future continuous IPC education and training.

REVIEW METHODS

An integrative literature review methodology was utilised to conduct a structured literature search within the last five years using CINAHL Plus, EMBASE, ERIC, MEDLINE, and PubMed databases. The following keywords were used: infection prevention and control; pre-registration nursing; higher education; core competencies in the databases. A total of 15 articles were identified under the inclusion criteria of peer-reviewed primary research in English on the pre-registration nurse population and their nursing programmes.

RESULTS

The final review of the 15 reports yielded continuous IPC education and training, knowledge, skills, and attitudes, and clinical placements as key components to develop and elevate student nurses' IPC core competencies.

CONCLUSION

All reports acknowledged the challenges of maintaining IPC core competencies and seeking diversified strategies to support continuous education and training utilising interactive tools embedded with simulated scenarios and quizzes, translating knowledge and skills to exemplary professional behaviours, and consistent academic and clinical support as the IPC demand intensifies.

Paramedic insertion of peripheral intravenous catheters, unused catheter rates, and influencing factors: A retrospective review

BACKGROUND

Peripheral intravenous catheters (PIVCs) are associated with adverse events such as bloodstream infections; thus clinically appropriate practice is important. However, there is limited research on PIVC use in ambulance settings. This study investigated the incidence of paramedic-inserted PIVCs, unused PIVCs, and factors that influenced practice.

METHODS

Electronic patient care records for Western Australian ambulance service patients who attended between January 1 and December 31, 2020 were retrospectively reviewed. Patient, environmental, and paramedic characteristics were explored. Binominal logistical regression models were used to identify factors associated with PIVC insertion and unused PIVCs.

RESULTS

A total of 187,585 records were included; 20.3% had a PIVC inserted and 44% remained unused. Factors associated with PIVC insertion were gender, age, problem urgency, chief complaint, and operational region. Age, chief complaint, and paramedic years of experience were associated with unused PIVCs.

DISCUSSION

This study identified multiple modifiable factors for the unnecessary insertion of PIVCs, which may be addressed through better education and mentoring of paramedics supported by clearer clinical guidelines.

CONCLUSIONS

This is, to our knowledge, the first Australian state-wide study to report unused paramedic-inserted PIVC rates. As 44% remained unused, clinical indication guidelines and intervention studies to reduce PIVC insertion are warranted.

Effectiveness of fit testing versus fit checking for healthcare workers respiratory protective equipment: A systematic review

Objectives

Respiratory protection is critical in healthcare to minimise the risk of airborne infections for healthcare workers (HCWs). It emphasizes the use of proper fitting of particulate filter respirators and equivalent respiratory protective equipment (RPE) to ensure a good facial seal. The systematic review aimed to compare the effectiveness of fit testing and fit checking for HCWs' respiratory protective equipment.

Methods

A systematic review of the literature exploring RPE for HCWs to determine the effectiveness of fit-testing versus fit-checking from January 2003 to April 2022 was identified using CINAHL Complete via EBSCO Host, Cochrane Library, EMBASE, PubMed, and MEDLINE via Ovid electronic databases, and grey literature. The study protocol was registered with PROSPERO (registration number: CRD42020213968).

Results

Of the 561 articles identified in the search, 25 articles (22 quantitative studies and three guidelines) were included in this review. Overall, these studies suggest fit-testing as a method that is more effective, widely adopted, and reliable in assessing the effectiveness of RPE; however, a respiratory program should include both fit-testing and fit-checking to maximise effectiveness of the RPE. The COVID-19 epidemic highlighted a lack of knowledge among HCWs regarding fit-checking and fit-testing, and relevant education increased the effectiveness of respiratory equipment protection.

Conclusion

It is imperative that both fit-testing and fit-checking is implemented in order to ensure HCW safety. It is recommended to integrate education, fit-testing and fit-checking into a comprehensive respiratory protective program run by trained fit-testers. There is also a need for practical testing methods that incorporate the clinical environment.

Mass behaviour change amid COVID-19: How public health information and social norms explain the transformation

COVID-19 is a severe and ongoing threat globally, with the spread disrupting lives and society. Despite the developments of vaccines, the key measure to reduce the transmission of variants has stemmed from mass changes to personal behaviours. COVID-19 pandemic offers a unique context, where the protection behaviours enacted by an individual are necessary to keep the community safe. A social psychological perspective can be used to understand the reasons for adherence to policies and determine what other factors can shape preventive behaviours. To resolve this, in partnership with health consumers we use an online survey, with the findings substantiating preventive behaviours are positively related to COVID-19 information access and descriptive norms. Additionally, findings demonstrate the mediating role of injunctive norms on preventive behaviour suggesting that policy makers can influence decision-making by promoting health information that provides guidance on acceptable behaviours, but also demonstrates subsequent success. The integrity of the model is substantiated by partial least squares (PLS) testing.

Barriers and facilitators to COVID-19 vaccine uptake among Australian health professional students during the pandemic: a nationwide study

Using a cross-sectional online survey we investigated knowledge, attitudes, and risk perception about COVID-19 vaccination and identified factors influencing vaccine uptake among Australian health professional students from October 2021 to January 2022. We analysed data from 1114 health professional students from 17 Australian universities. Most participants were enrolled in nursing programs (n = 958, 86.8%), and 91.6% (n = 858) of the participants received COVID-19 vaccination. Approximately 27% believed COVID-19 was no more serious than seasonal influenza and that they had a low risk of acquiring COVID-19. Nearly 20% disagreed that COVID-19 vaccines in Australia were safe and perceived they were at higher-risk of acquiring COVID infection than the general population. Higher-risk perception viewing vaccination as their professional responsibility, and vaccine mandate strongly predicted vaccination behaviour. Participants consider COVID-19 information from health professionals, government websites, and World Health Organization as the most trusted information sources. The findings highlight that healthcare decision-makers and university administrators need to monitor students' hesitancy with vaccination to improve students' promotion of the vaccination to the general population.

Investigation of the selection and use of "other" personal protective equipment to prevent mucous membrane exposure in nurses: A cross-sectional study

BACKGROUND

Selection and use of personal protective equipment (PPE) to prevent non-percutaneous body fluid exposure (NP BFE) is determined by a clinical assessment of risk. The aim of this study was to explore the selection and use of PPE, particularly masks and eye protection to prevent NP BFE, by nurses.

METHODS

This quantitative single-site two-phased study was guided by the Health Belief Model (HBM). Phase 1 was a retrospective electronic database audit of body fluid exposure surveillance data. Phase 2 included a cross-sectional survey.

RESULTS

The highest incidence of reported NP BFE to non-intact skin and mucous membranes during the study period were identified in the emergency department (ED) at 51.3% (20/39), intensive care unit (ICU) at 30.8% (12/39), operating theatre (OT) with 12.9% (5/39), and inpatient renal ward with 5.1% (2/39). Reported PPE use during NP BFE was: 0% face shields or masks, 10% gown/apron, and 15% goggles. Survey results related to Prevention of mucocutaneous exposures were similar across all high-risk units, though ED nurses reported poorer compliance with the use of PPE to prevent exposure. Risk assessment for prevention of NP BFE was reported, yet there was a lack of compliance. The ICU results indicated a positive safety culture in contrast to the ED.

CONCLUSION

The findings are consistent with research identifying inadequate prevention of NP BFE, although nurses are aware of the importance of risk assessment. The HBM has the potential to increase understanding of the differences in nurses' perceptions of risk in safety culture.

The role of online marketing to engage healthcare workers with infection prevention and control information and resources: A pilot study

BACKGROUND

The successful adoption and application of infection prevention and control (IPC) principles in all healthcare settings is dependent on the degree to which healthcare workers (HCWs) are aware of the requirements, have access to program resources and information, and engage with the IPC program. This study investigates the impact of redesigning the Infection Control Department (ICD) intranet site based on user feedback followed by a targeted marketing campaign to improve website usability, awareness, and access.

METHODS

In this systematic study, we used a survey plus two focus group interviews to elicit user requirements for the content and look of the ICD intranet page and identify the best communication platforms to use for the marketing campaign to launch the redesigned intranet page. The information was used to redesign the intranet page and develop the marketing campaign. The survey was repeated post-intervention and these results, along with a comparison of website analytics monitoring traffic, were used to determine the success of the intervention.

RESULTS

The ICD intranet page redesign increased the information and resources. Post-intervention survey results demonstrated a significant improvement in user satisfaction including ease of navigation and access to IPC information and resources. The marketing campaign resulted in a significant increase in website traffic to the ICD intranet page, demonstrating enhanced engagement with HCWs.

CONCLUSION

This study demonstrated that website redesign based on user feedback, combined with a marketing campaign, can increase the traffic to the website and improve the user experience when accessing and navigating the site making the information and resources more accessible to HCWs.

Tuberculosis infection prevention and control in rural Papua New Guinea: an evaluation using the infection prevention and control assessment framework

BACKGROUND

Papua New Guinea (PNG) is one of the 14 countries categorised as having a triple burden of tuberculosis (TB), multidrug-resistant TB (MDR TB), and TB-human immunodeficiency virus (HIV) co-infections. TB infection prevention and control (TB-IPC) guidelines were introduced in 2011 by the National Health Department of PNG. This study assesses the implementation of this policy in a sample of district hospitals in two regions of PNG.

METHODS

The implementation of TB-IPC policy was assessed using a survey method based on the World Health Organization (WHO) IPC assessment framework (IPCAF) to implement the WHO's IPC core components. The study included facility assessment at ten district hospitals and validation observations of TB-IPC practices.

RESULTS

Overall, implementation of IPC and TB-IPC guidelines was inadequate in participating facilities. Though 80% of facilities had an IPC program, many needed more clearly defined IPC objectives, budget allocation, and yearly work plans. In addition, they did not include senior facility managers in the IPC committee. 80% (n = 8 of 10) of hospitals had no IPC training and education; 90% had no IPC committee to support the IPC team; 70% had no surveillance protocols to monitor infections, and only 20% used multimodal strategies for IPC activities. Similarly, 70% of facilities had a TB-IPC program without a proper budget and did not include facility managers in the TB-IPC team; 80% indicated that patient flow poses a risk of TB transmission; 70% had poor ventilation systems; 90% had inadequate isolation rooms; and though 80% have personal protective equipment available, frequent shortages were reported.

CONCLUSIONS

The WHO-recommended TB-IPC policy is not effectively implemented in most of the participating district hospitals. Improvements in implementing and disseminating TB-IPC guidelines, monitoring TB-IPC practices, and systematic healthcare worker training are essential to improve TB-IPC guidelines' operationalisation in health settings to reduce TB prevalence in PNG.

Barriers to, and enablers of, paramedics responding to suspected or confirmed COVID-19 cases: An integrative review

BACKGROUND

The coronavirus pandemic (COVID-19) has focused attention on healthcare workers' concerns about working during a pandemic, yet research on the effect of the pandemic specifically on paramedics is lacking. This literature review aims to critically examine the current knowledge of paramedics' experience of barriers to, and enablers of, responding to suspected or confirmed COVID-19 cases.

METHODS

An integrative review was undertaken using articles found by a systematic search of four research databases. Inclusion criteria included paramedics or emergency medical technicians who had experience of barriers or enablers responding to patients during the coronavirus pandemic.

RESULTS

Nine articles met the inclusion and exclusion criteria. Barriers included communication and poor leadership, fear of infection to self and family, frequent changes in guidelines and inconsistencies across agencies, stress/burnout, and concerns with personal protective equipment. Enablers included job security, perceived social support, solidarity with other paramedics, and use of modern technologies for communication.

CONCLUSIONS

There are unique experiences of working during the COVID-19 pandemic in the prehospital environment. Particular challenges occurred with leadership, communication within the organisation and between agencies, and working in an unpredictable environment.

Infection prevention and control program assessment tools: A comparative study

BACKGROUND

Infection prevention and control program (IPCP) assessment tools help to identify the improvement needs. This study aimed to identify fit-for-purpose of 3 IPCP assessment tools.

METHODS

An exploratory mixed-method study was performed from 2018-2019 in Brazil, using a convenience sample of IPC professionals with various levels of experience to evaluate the IPCP tools: (1) the WHO Infection Prevention and Control Assessment Framework at the Facility Level (IPCAF), (2) the University of Sao Paulo IPCP tool (OGIPCP), and (3) the Infection Prevention and Control Programme Evaluation (IPCPE) tool. A quantitative survey followed by a semi-structured interview accessed the participants' perceptions about these tools. Quantitative data analysis were descriptive and qualitative data were thematical.

RESULTS

IPCPE was considered more complete, better for effectiveness, easy to apply, and with easily interpreted indicators. IPCAF was the best regarding to purpose, easy reporting, and interpretation; however, requires professional experience. OGIPCP have the fastest application, easy to understand, and easily calculated indicators, requiring less experience. Qualitative data endorsed the quantitative results and showed IPCPE and IPCAF tools as the most accepted.

CONCLUSIONS

The 3 assessment tools for IPCP have similar potential for use to support improvements in the IPCP. The IPCPE and IPCAF were considered advantageous on the effectiveness and fit-for-purpose compared to OGIPCP, despite the higher familiarity of participants with this tool.

Audit of essential infection prevention and control content provided within undergraduate/postgraduate public health programs across Australian and New Zealand universities

BACKGROUND

To describe and analyse the infection prevention and control (IPC) curricula within Public Health degrees across Australian and New Zealand Universities and identify foundational IPC knowledge deficits.

METHODS

A cross-sectional study of public health and related programs across tertiary education institutions within Australia and New Zealand was conducted to comprehensively illustrate the current inclusion of IPC core and elective courses and identify areas of IPC content deficit.

RESULTS

Australian (n = 32) and New Zealand (n = 9) universities were audited, consisting of 217 public health/public health related degrees within Australia and 45 within New Zealand. Within Australia 41% of public health degrees and 49% in New Zealand did not offer any IPC content as core or elective subjects.

CONCLUSIONS

Public health tertiary education in Australia and New Zealand is lacking in equipping and imbedding IPC skills and knowledge in public health graduates. This highlights the need for a framework guiding mandatory IPC content within Australian and New Zealand public health programs.

Barriers associated with mandatory influenza vaccination policies for healthcare workers: an integrative review

BACKGROUND

Uptake of influenza vaccination reduces staff absenteeism as well as mortality of patients and healthcare workers (HCWs); however, adherence of HCWs to annual influenza vaccination is poor and some healthcare facilities are now considering mandatory influenza vaccination policies.

AIM

The purpose of this study was to identify the perceived and reported barriers to the implementation of a mandatory influenza vaccination policy for HCWs.

METHODS

An integrative review of the literature was conducted. Databases including CINAHL, Cochrane Library, Medline and PubMed were searched using key terms. The quality of papers was assessed utilising the Standard Quality Assessment Criteria for Evaluating Primary Research papers for a Variety of Fields which consisted of 10 questions with a possible total score of 20. PRISMA guidelines were used to report the search outcomes.

RESULTS

A total of 68 papers were identified from the database search. Seven papers were relevant, following screening. The quality scores of these were in the range of 15-20. A number of barriers are reported to prevent the effective implementation of mandatory influenza vaccination policies including ethical and legal considerations, logistics, healthcare burden, leadership and management, and human factors such as HCWs' perspectives.

CONCLUSIONS

By comprehensively identifying these, barriers can be addressed to allow effective implementation of such policies in healthcare facilities to ensure improved outcomes. The results of the review indicated the need for further research to ensure that barriers are addressed cohesively.

The "five senses of success" in nursing students: Assessing first-year support engagement

Objectives

This study aimed to identify School and University support services available and accessed by nursing students transitioning into a university environment as many struggle to adjust to competing demands of personal commitments and expectations at university.

Methods

A mixed methods design was used, based on activity theory and Lizzio's Five Senses of Success frameworks as exploratory guides. This study was conducted amongst the first year cohort at one campus of the Bachelor of Nursing (BN) program in Queensland, Australia. An initial baseline assessment of what University and School-based support services were on offer for students, and how the students interacted with the support services was conducted. This was followed by a survey to identify awareness and access to support services. Focus groups were then conducted to clarify the previous results and to determine engagement with these support services.

Results

A randomly selected number of students (n = 150) in the first-year 2014 cohort of the BN program (n = 300) were included in this study. The survey was completed by 54 students and three semi-structured focus groups were conducted. The analysis indicated that the support services in place were successful in reaching the majority of students and contributed to their sense of success at university. Specifically students identified that a whole cohort approach to support enhanced their transition to university.

Conclusion

Identifying lesser known services early in the first year will ensure that students are supported and encouraged to use all services, contributing to their sense of success at university.

Instilling a culture of cleaning: Effectiveness of decontamination practices on non-disposable sphygmomanometer cuffs

Background

Sphygmomanometers and their cuffs are non-critical items that can act as a fomite for transmission of pathogens which may cause healthcare-associated infection (HAI), leading to an argument that disposable equipment improves patient safety.

Aim

The aim of this study was to demonstrate that decontamination decreased in microbial contamination of non-disposable sphygmomanometer cuffs, providing evidence to negate the need to purchase, and dispose of, single-patient-use cuffs, reducing cost and environmental impact.

Methods

A pre-post intervention study of available sphygmomanometer cuffs and associated bedside patient monitors was conducted using a series of microbiological samples in a rural emergency department. A Wilcoxon signed-rank test analysed the effect of the decontamination intervention. To further examine the effect of the decontamination intervention, Mann-Whitney U-tests were conducted for each aspect.

Findings

Contamination was significantly higher before decontamination than afterwards (Z = -5.14, U = 55.0, P < 0.001, η2 = 0.61 inner; Z = -5.05, U = 53.5, P < 0.001, η2 = 0.59 outer).

Discussion

Decontamination of non-disposable sphygmomanometer cuffs decreases microbial load and risk of HAI, providing evidence to negate arguments for disposable cuffs while being environmentally sensitive and supportive of a culture of patient safety and infection control.

Infectious illness prevention and control methods and their effectiveness in non-health workplaces: an integrated literature review

BACKGROUND

Infectious illness in the workplace places a substantial cost burden on employers due to productivity losses from employee absenteeism and presenteeism.

AIM

Given the clear impacts of infectious illness on workplaces, this review aimed to investigate the international literature on the effectiveness and cost-benefit of the strategies non-healthcare workplaces use to prevent and control infectious illnesses in these workplaces.

METHODS

MEDLINE, CINAHL Plus with Fulltext and Business Source Complete were searched concurrently using EBSCO Host 1995-2016.

FINDINGS

Infection prevention and control strategies to reduce workplace infectious illness and absenteeism evaluated in the literature include influenza vaccination programs, use of alcohol-based hand sanitiser and paid sick days. While the reported studies have various methodological flaws, there is good evidence of the effectiveness of influenza vaccination in preventing workplace infectious illness and absences and moderate evidence to support hand hygiene programs.

DISCUSSION

Some studies used more than one intervention concurrently, making it difficult to determine the relative benefit of each individual strategy. Workplace strategies to prevent and control infectious illness transmission may reduce costs and productivity losses experienced by businesses and organisations related to infectious illness absenteeism and presenteeism.

A healthy degree of suspicion: A discussion of the implementation of transmission based precautions in the emergency department

Background

Emergency department (ED) presentations have increased significantly domestically and internationally. Swift identification and implementation of transmission based precautions (TBP) for patients known or suspected of having an epidemiologically important pathogen is important. ED staff, particularly triage nurses, are pivotal in detecting and preventing infection, including healthcare associated infections (HAI).

Methods

MEDLINE, CINAHL, PubMed and Ovid were searched for articles published between 2004 and 2015 using key search terms: infection control/prevention and emergency department(s), triage, and transmission based precautions and emergency department(s), and triage, to identify common themes for discussion. Systematic review/meta-analysis was not in the scope of this exploration.

Findings

Themes were identified relating to HAI and ED practices and grouped into: assisted detection of conditions for which TBP is required, ED and TBP, mass-causality event/bioterrorism/pandemic/epidemic, infection control not TBP and multi-resistant organisms not TBP. The literature is heavily influenced by worldwide epidemic/pandemics and bioterrorist risks resulting in increased awareness of the importance of swift identification of syndromes that require TBP, but only in these situations.

Conclusion

Implementation of appropriate TBP, changing triage practices, training and measures to assist decision-making could assist in preventing HAI in the ED context. A systematic quantitative review of the literature is recommended to guide practice change research.

Success in the South Pacific: a case study of successful diffusion of an infection prevention and control program

INTRODUCTION

The aim of this study was to explore the role of the Diffusion of Innovations framework in adopting an infection prevention and control program (IPCP) in a low and middle income (LMI) country, the Republic of Kiribati.

METHODS

Case-study methodology was used to examine and contextualise the analysis of the Republic of Kiribati's adoption of the IPCP from 2003 to 2010. Data were collected from multiple sources including semi-structured interviews, IPCP documentation, program evaluation and a healthcare worker survey. Data were subjected to thematic analysis and descriptive statistics where relevant to the study design.

RESULTS

It was found that the self-initiated progression of activities and stimuli has resulted in the successful adoption of a comprehensive IPCP. The process followed the staged model of the classic Diffusion of Innovations process in organisations described by Everett Rogers.

CONCLUSION

This case study provides an illustration of how a comprehensive IPCP can be adopted in a LMI country setting with little involvement from external agencies. It identifies key stimuli, opportunities and activities which could be similarly adopted and implemented by other LMI countries.

Variation in human β-defensin genes: new insights from a multi-population study

Human β-defensin 2 (hBD-2) and hBD-3, encoded by DEFB4 and DEFB103A, respectively, have shown anti-HIV activity, and both genes exhibit copy number variation (CNV). Although the role of hBD-1, encoded by DEFB1, in HIV-1 infection is less clear, single nucleotide polymorphisms (SNPs) in DEFB1 may influence viral loads and disease progression. We examined the distribution of DEFB1 SNPs and DEFB4/103A CNV, and the relationship between DEFB1 SNPs and DEFB4/103A CNV using samples from two HIV/AIDS cohorts from the United States (n = 150) and five diverse populations from the Coriell Cell Repositories (n = 46). We determined the frequencies of 10 SNPs in DEFB1 using a post-PCR, oligonucleotide ligation detection reaction-fluorescent microsphere assay, and CNV in DEFB4/103A by real-time quantitative PCR. There were noticeable differences in the frequencies of DEFB1 SNP alleles and haplotypes among various racial/ethnic groups. The DEFB4/103A copy numbers varied from 2 to 8 (median, 4), and there was a significant difference between the copy numbers of self-identified whites and blacks in the US cohorts (Mann-Whitney U-test P = 0.04). A significant difference was observed in the distribution of DEFB4/103A CNV among DEFB1 -52G/A and -390T/A genotypes (Kruskal-Wallis P = 0.017 and 0.026, respectively), while not in the distribution of DEFB4/103A CNV among -52G/A_-44C/G_-20G/A diplotypes. These observations provide additional insights for further investigating the complex interplay between β-defensin genetic polymorphisms and susceptibility to, or the progression or severity of, HIV infection/disease.

Glycophorin C delta(exon3) is not associated with protection against severe anaemia in Papua New Guinea

The high frequencies of mutant haemoglobin and erythrocyte surface proteins in malaria-endemic regions have indicated that polymorphisms in human genes have been under selection pressure by severe malarial disease. Glycophorin C (GYPC) is a major surface erythrocyte protein and also a receptor for the Plasmodium falciparum erythrocyte-binding antigen 140 (EBA-140, also known as BAEBL). There is no binding to GYPC in Gerbich-negative (deletion of exon 3 in GYPC gene: GYPCC delta(exon3)) erythrocytes by EBA-140, hence limiting invasion of erythrocytes by certain P. falciparum lines. The GYPCC delta(exon3) allele reaches high frequencies in two areas of Papua New Guinea (PNG) where malaria is highly endemic. There is, however, no indication that Gerbich negativity protects against malaria-related illness. Using archival blood samples collected from children (<6 years of age) in the Wosera District, East Sepik Province, PNG, we investigated GYPC C delta(exon3) as a possible genetic component of protection against severe malarial anaemia (SMA). The frequency of this human genetic polymorphism was found to be in accordance with previous studies. However, our result showed no association between SMA and GYPC C delta(exon3). Until such an association is clearly shown with severe malaria outcomes, these results raise questions regarding the role of malaria as a selective force for Gerbich negativity.

Dynamic regulation of single- and mixed-species malaria infection: Insights to specific and non-specific mechanisms of control

Our increasing appreciation of the high prevalence of mixed-species Plasmodium infection in malaria-endemic regions has resulted in controversy regarding the likely mechanism(s) of regulation for mixed parasite burden within an individual human host. In the present study, we examined dynamic models of Plasmodium spp. regulation by fever and by non-specific (NS) and species-specific (SS) immunity (including the influence of their variable time-delays, duration, and efficacy) in order to assess the likely role of these factors in regulating detectable parasitemia and clinical disease. Our models suggest that in order to observe the irregular waves of fever and parasitemia that are often found in multiply infected subjects, there must be a differential SS immune effect (beyond the regulatory effects of the species-transcendent density-dependent factors previously posited to control mixed-species parasitemia), and time-dependent variation in immunity to the dominant species. By implementation of individual SS immune controls of non-permanent duration, the resulting multi-dimensional model can be viewed as multiple single-species oscillators coupled via a NS species-transcendent controller. This extended model exhibits the essential patterns of long-term mixed infections. Although this 'circuit-immunity' model gives only a qualitative estimate of the complex web of participating agents and reaction pathways, it provides a starting point for future studies of the specific and NS within-host mechanisms that regulate mixed-species malaria infection.

Expression of Duffy antigen receptor for chemokines during reticulocyte maturation: using a CD71 flow cytometric technique to identify reticulocytes

Flow cytometric methods commonly used to identify reticulocytes are of limited usefulness in malarious areas, since RNA staining also detects plasmodia. An important antigen expressed on reticulocytes is Duffy antigen receptor for chemokines (DARC, also known as Fy), the receptor for Plasmodium vivax. An early marker for reticulocytes is CD71 (transferrin receptor). We have been interested in CD71 as an alternative marker for reticulocytes in the context of Fy expression. Flow cytometry was used to determine the expression of Fy on CD71-positive and -negative reticulocytes and to correlate serology and genotype. A reduction of 13 percent was seen in Fy6 expression between CD71-positive reticulocytes and RNA-positive reticulocytes. CD71 disappears early during reticulocyte maturation, while Fy6 expression is relatively preserved. CD71 is an alternative to staining for RNA for reticulocyte assays relating to Fy6 expression.

Polymorphisms of innate immunity genes and susceptibility to lymphatic filariasis

We examined 906 residents of an area of Papua New Guinea where bancroftian filariasis is endemic for genetic polymorphisms in three innate immunity genes suspected of contributing to susceptibility to infection and lymphatic pathology. Active infection was confirmed by the presence of blood-borne microfilariae and circulating filarial antigen in plasma. Disease was ascertained by physical examination for the presence of overt lymphedema (severe swelling of an arm or leg) or hydrocele. There was no association of infection status, lymphedema of an extremity, or hydrocele with chitotriosidase genotype (CHIT1). Polymorphisms of toll-like receptor-2 and toll-like receptor-4 genes (TLR4 A896G; TLR2 T2178A, G2258A) were not detected (N=200-625 individuals genotyped) except for two individuals heterozygous for a TLR2 mutation (C2029 T). These results indicate that a CHIT1 genotype associated previously with susceptibility to filariasis in residents of southern India and TLR2 and TLR4 polymorphisms do not correlate with infection status or disease phenotype in this Melanesian population.

CR1 Knops blood group alleles are not associated with severe malaria in the Gambia

The Knops blood group antigen erythrocyte polymorphisms have been associated with reduced falciparum malaria-based in vitro rosette formation (putative malaria virulence factor). Having previously identified single-nucleotide polymorphisms (SNPs) in the human complement receptor 1 (CR1/CD35) gene underlying the Knops antithetical antigens Sl1/Sl2 and McC(a)/McC(b), we have now performed genotype comparisons to test associations between these two molecular variants and severe malaria in West African children living in the Gambia. While SNPs associated with Sl:2 and McC(b+) were equally distributed among malaria-infected children with severe malaria and control children not infected with malaria parasites, high allele frequencies for Sl 2 (0.800, 1,365/1,706) and McC(b) (0.385, 658/1706) were observed. Further, when compared to the Sl 1/McC(a) allele observed in all populations, the African Sl 2/McC(b) allele appears to have evolved as a result of positive selection (modified Nei-Gojobori test Ka-Ks/s.e.=1.77, P-value <0.05). Given the role of CR1 in host defense, our findings suggest that Sl 2 and McC(b) have arisen to confer a selective advantage against infectious disease that, in view of these case-control study data, was not solely Plasmodium falciparum malaria. Factors underlying the lack of association between Sl 2 and McC(b) with severe malaria may involve variation in CR1 expression levels.

Expansion of the Knops blood group system and subdivision of Sl(a)

BACKGROUND

Complement receptor type 1 (CR1), which bears the Knops (Kn [KN]) blood group antigens, is involved in the rosetting of Plasmodium falciparum- infected RBCs with uninfected cells. As a first step in understanding this interaction, the molecular basis for the blood group antigens encoded by CR1 was investigated.

STUDY DESIGN AND METHODS

An antibody from a white donor who exhibited an apparent anti-Sl(a) was used for population studies of several racial groups. The donor's genomic DNA was sequenced to identify the Sl(a) mutation and other mutations.

RESULTS

The donor with anti-Sl(a) typed as Sl(a+) with some sera and had the CR1 genotype AA at bp 4828 (R1601). However, she was homozygous for a new mutation (GG) at bp 4855 changing amino acid 1610 from S1610 to T1610 (S1610T). This mutation occurred in heterozygous form in eight white and one Asian donor. The site is only nine amino acids from the previously described Sl(a) polymorphism and appears to produce a new conformational epitope.

CONCLUSION

The antigen formerly known as Sl(a) can now be subdivided. A new terminology is proposed that recognizes both linear and conformational epitopes on the CR1 protein. At amino acid 1601, Sl 1 (Sl(a)) is represented by R, Sl 2 (Vil) is represented by glycine, and Sl 3 requires both R1601 and S1610. Sl 4 and Sl 5 are hypothetical epitopes represented by S1610 and T1610, respectively.

The association of the glycophorin C exon 3 deletion with ovalocytosis and malaria susceptibility in the Wosera, Papua New Guinea

Erythrocyte polymorphisms, including ovalocytosis, have been associated with protection against malaria. This study in the Wosera, a malaria holoendemic region of Papua New Guinea, examined the genetic basis of ovalocytosis and its influence on susceptibility to malaria infection. Whereas previous studies showed significant associations between Southeast Asian ovalocytosis (caused by a 27- base pair deletion in the anion exchanger 1 protein gene) and protection from cerebral malaria, this mutation was observed in only 1 of 1019 individuals in the Wosera. Polymerase chain reaction strategies were developed to genotype individuals for the glycophorin C exon 3 deletion associated with Melanesian Gerbich negativity (GPCDeltaex3). This polymorphism was commonly observed in the study population (GPCDeltaex3 frequency = 0.465, n = 742). Although GPCDeltaex3 was significantly associated with increased ovalocytosis, it was not associated with differences in either Plasmodium falciparum or P vivax infection measured over the 7-month study period. Future case-control studies will determine if GPCDeltaex3 reduces susceptibility to malaria morbidity.

Evolution of a unique Plasmodium falciparum chloroquine-resistance phenotype in association with pfcrt polymorphism in Papua New Guinea and South America

The mechanistic basis for chloroquine resistance (CQR) in Plasmodium falciparum recently has been linked to the polymorphic gene pfcrt. Alleles associated with CQR in natural parasite isolates harbor threonine (T), as opposed to lysine (K) at amino acid 76. P. falciparum CQR strains of African and Southeast Asian origin carry pfcrt alleles encoding an amino acid haplotype of CVIET (residues 72-76), whereas most South American CQR strains studied carry an allele encoding an SVMNT haplotype; chloroquine-sensitive strains from malarious regions around the world carry a CVMNK haplotype. Upon investigating the origin of pfcrt alleles in Papua New Guinean (PNG) P. falciparum we found either the chloroquine-sensitive-associated CVMNK or CQR-associated SVMNT haplotypes previously seen in Brazilian isolates. Remarkably we did not find the CVIET haplotype observed in CQR strains from Southeast Asian regions more proximal to PNG. Further we found a previously undescribed CQR phenotype to be associated with the SVMNT haplotype from PNG and South America. This CQR phenotype is significantly less responsive to verapamil chemosensitization compared with the effect associated with the CVIET haplotype. Consistent with this, we observed that verapamil treatment of P. falciparum isolates carrying pfcrt SVMNT is associated with an attenuated increase in digestive vacuole pH relative to CVIET pfcrt-carrying isolates. These data suggest a key role for pH-dependent changes in hematin receptor concentration in the P. falciparum CQR mechanism. Our findings also suggest that P. falciparum CQR has arisen through multiple evolutionary pathways associated with pfcrt K76T.

HIV nephropathy and the Duffy antigen/receptor for Chemokines in African Americans

BACKGROUND AND OBJECTIVES

HIV nephropathy (HIVAN) is markedly racially biased in its distribution, occurring in about 10% of HIV infected African Americans according to some studies. Based upon previous laboratory and epidemiological studies, the Duffy promoter polymorphism, which occurs almost exclusively in individuals of African descent, has been postulated to be the predisposing factor. We aimed to explore that relationship by directly genotyping individuals with HIV nephropathy to determine the proportion homozygous for this mutation to test the hypothesis it was responsible for the genetic component of this disease. We anticipated that if the polymorphism was associated with HIV nephropathy all individuals would be homozygous for this mutation.

METHOD

Individuals with HIVAN proven on biopsy were identified from previous studies and a pre-existing clinical database. This diagnosis was confirmed by an experienced pathologist examining the biopsies in a blinded fashion. PCR and RFLP strategies were used on the biopsy samples to genotype for the Duffy promoter polymorphism. The cases were compared to a control population of HIV seronegative African Americans.

RESULTS

Twenty African American individuals with HIV nephropathy were successfully genotyped. Only nine were homozygous for the promoter mutation. Nine were heterozygous and two homozygous wild type. Furthermore, the frequency of the polymorphism did not differ from the background rate in the African American population (OR = 0.788 95% confidence intervals 0.378-1.64).

CONCLUSION

The Duffy promoter polymorphism was not disproportionately represented in persons with HIVAN calling into question any significant role in the pathogenesis of HIVAN.

Genetic polymorphisms in molecules of innate immunity and susceptibility to infection with Wuchereria bancrofti in South India

A pilot study was conducted to determine if host genetic factors influence susceptibility and outcomes in human filariasis. Using the candidate gene approach, a well-characterized population in South India was studied using common polymorphisms in six genes (CHIT1, MPO, NRAMP, CYBA, NCF2, and MBL2). A total of 216 individuals from South India were genotyped; 67 normal (N), 63 asymptomatic microfilaria positive (MF+), 50 with chronic lymphatic dysfunction/elephantiasis (CP), and 36 tropical pulmonary eosinophilia (TPE). An association was observed between the HH variant CHIT1 genotype, which correlates with decreased activity and levels of chitotriosidase and susceptibility to filarial infection (MF+ and CP; P = 0.013). The heterozygosity of CHIT1 gene was over-represented in the normal individuals (P = 0.034). The XX genotype of the promoter region in MBL2 was associated with susceptibility to filariasis (P = 0.0093). Since analysis for MBL-sufficient vs insufficient haplotypes was not informative, it is possible the MBL2 promoter association results from linkage disequilibrium with neighboring loci. We have identified two polymorphisms, CHIT1 and MBL2 that are associated with susceptibility to human filarial infection, findings that merit further follow-up in a larger study.

Molecular identification of Knops blood group polymorphisms found in long homologous region D of complement receptor 1

Complement receptor 1 (CR1) has been implicated in rosetting of uninfected red blood cells to Plasmodium falciparum-infected cells, and rosette formation is associated with severe malaria. The Knops blood group (KN) is located on CR1 and some of these antigens, ie, McCoy (McC) and Swain-Langley (Sl(a)), show marked frequency differences between Caucasians and Africans. Thus, defining the molecular basis of these antigens may provide new insight into the mechanisms of P falciparum malaria. Monoclonal antibody epitope mapping and serologic inhibition studies using CR1 deletion constructs localized McC and Sl(a) to long homologous repeat D of CR1. Direct DNA sequencing of selected donors identified several single nucleotide polymorphisms in exon 29 coding for complement control protein modules 24 and 25. Two of these appeared to be blood group specific: McC associated with K1590E and Sl(a) with R1601G. These associations were confirmed by inhibition studies using allele-specific mutants. A sequence-specific oligonucleotide probe hybridization assay was developed to genotype several African populations and perform family inheritance studies. Concordance between the 1590 mutation and McC was 94%; that between Sl(a) and 1601 was 88%. All but 2 samples exhibiting discrepancies between the genotype and phenotype were found to be due to low red cell CR1 copy numbers, low or absent expression of some alleles, or heterozygosity combined with low normal levels of CR1. These data further explain the variability observed in previous serologic studies of CR1 and show that DNA and protein-based genetic studies will be needed to clarify the role of the KN antigens in malaria.

Duffy-null promoter heterozygosity reduces DARC expression and abrogates adhesion of the P. vivax ligand required for blood-stage infection

The Duffy blood group antigen is an essential receptor for Plasmodium vivax entry into erythrocytes in a process mediated by the parasite ligand, the Duffy binding protein (DBP). Recently, individuals living in a malaria endemic region of Papua New Guinea were identified as heterozygous for a new allele conferring Duffy negativity, which results in 50% less Duffy antigen on their erythrocytes. We demonstrate that DBP adherence to erythrocytes is significantly reduced for erythrocytes from heterozygous individuals who carry one Duffy antigen negativity allele. These data provide evidence that emergence of this new allelic form of Duffy negativity is correlated with resistance against vivax malaria.

Chemokine RANTES promoter polymorphism affects risk of both HIV infection and disease progression in the Multicenter AIDS Cohort Study

OBJECTIVE

To examine whether polymorphism in the RANTES gene is associated with HIV disease outcome.

DESIGN

RANTES, a ligand of the major HIV co-receptor, CCR5, is known to block HIV-CCR5 interactions. Recently, two single nucleotide polymorphisms in the RANTES gene promoter region, designated -403G/A and -28C/G, have been described. Both polymorphisms can affect in-vitro promoter activity, and the RANTES -403A, -28G haplotype has been associated with a slower CD4 cell count decline rate in a Japanese cohort.

METHODS

We compared RANTES compound genotype frequencies between HIV-positive and exposed-uninfected participants of the Multicenter AIDS Cohort Study (MACS) and rates of progression to AIDS for MACS seroconverters.

RESULTS

We found that the two most common RANTES promoter compound genotypes, G1 (-403G/G, -28C/C) found in 67% of Caucasians, and G4 (-403G/A, -28C/C) found in 23% of Caucasians, were associated with altered risk of HIV transmission and progression, particularly in individuals who lacked the protective CCR5 mutation, CCR5delta32. In this study, individuals with a G4 compound genotype were more likely to acquire HIV than individuals with a G1 compound genotype (OR 1.72, P = 0.016) and the risk increased when individuals possessing CCR5delta32 were omitted from consideration (OR 2.13, P = 0.005). Among seroconverters lacking CCR5delta32, those who had the G4 compound genotype progressed significantly slower to AIDS-1993 than those with the G1 compound genotype (median time to AIDS 7.6 versus 5.4 years; RH 0.65; P = 0.007).

CONCLUSIONS

These data implicate the RANTES-403A allele as a risk factor for HIV transmission and as a protective factor for HIV progression.

Differential expression of the duffy antigen receptor for chemokines according to RBC age and FY genotype

BACKGROUND

The Duffy (Fy) blood group (also known as Duffy antigen receptor for chemokines, or DARC) may be involved in regulation of the level of circulating proinflammatory chemokines, and it is an obligatory receptor on RBCs for the human malaria parasite Plasmodium vivax.

STUDY DESIGN AND METHODS

Because quantification of Fy expression by using RBCs of various ages will not detect acute changes associated with inflammatory states, and because P. vivax exclusively invades reticulocytes, a flow cytometric method was developed to measure the level of surface expression of Fy. Reticulocytes and mature RBCs from persons with different genotypes (GATA-1 T-->C promoter mutation at nt -46; FY*A and FY*B in the ORF) were used.

RESULTS

Expression of the Fy6 epitope, which is required for P. vivax invasion, was 49 +/- 19 percent higher on reticulocytes than on mature RBCs, regardless of donor genotype (p<0.0001). Fy6 levels were approximately 50 percent lower in persons who were heterozygous for the GATA-1 promoter mutation and were significantly lower on reticulocytes and mature RBCs of the FY*B/FY*B genotype than on those of the FY*A/FY*A or FY*A/FY*B genotype.

CONCLUSION

Fy has greater expression on reticulocytes than on mature RBCs in flow cytometry. This method may be useful in further studies of this antigen, such as characterization of reticulocytes and RBC phenotypes across populations, in response to chemokine regulation, and in the context of susceptibility to P. vivax and other parasites.

Application of a polymerase chain reaction-ELISA to detect Wuchereria bancrofti in pools of wild-caught Anopheles punctulatus in a filariasis control area in Papua New Guinea

Chemotherapy-based eradication programs are aimed at stopping transmission of Wuchereria bancrofti by its obligatory mosquito vector. This study compares one year post-treatment W. bancrofti infection rates of Anopheles punctulatus, the main vector of lymphatic filariasis in Papua New Guinea, using traditional dissection techniques and a polymerase chain reaction (PCR)-based ELISA of a parasite-specific Ssp I repeat. A total of 633 mosquitoes in 35 batches were dissected. Six batches contained W. bancrofti-infected mosquitoes, giving a minimum infection rate of 0.9%. This value was not different than the actual infection rate, which was 9 (1.4%) of 633 mosquitoes (P = 0.48). The DNA was extracted from 47 pools containing a mean of 13.2 mosquitoes per pool. A total of 621 mosquitoes were processed for the PCR-ELISA, including 486 caught by human bait and 135 by light trap, which included both dead and live mosquitoes. Of 23 pools of alcohol-preserved human-bait mosquitoes, seven were positive by the PCR-ELISA, giving an infection rate identical to that obtained by dissection of individual mosquitoes (1.4%). The minimum infection rates for pools of light-trap mosquitoes found dead and alive were 2.7% (2 of 74) and 4.9% (3 of 61), respectively. These values did not differ from each other (P = 0.84), but the overall infection rate of light-trap mosquitoes was greater than that of mosquitoes captured by human bait (3.7% versus 1.4%; P = 0.09). These data indicate that the PCR-ELISA of a W. bancrofti Ssp I repeat using pools of mosquitoes is comparable to traditional dissection techniques for monitoring transmission intensity following introduction of mass chemotherapy. This approach may also be useful for rapid and cost-effective assessment of transmission in endemic areas where the frequency of overt lymphatic pathology is low.

Random distribution of mixed species malaria infections in Papua New Guinea

Plasmodium falciparum (Pf), P. vivax (Pv), P. malariae (Pm), and P. ovale (Po) infections are endemic in coastal areas of Papua New Guinea. Here 2,162 individuals living near Dreikikir, East Sepik Province, have been analyzed for complexity of malaria infection by blood smear and polymerase chain reaction (PCR) diagnoses. According to blood smear, the overall prevalence of Plasmodium infection was 0.320. Most individuals (0.283) were infected with a single species only. The prevalence of mixed species infections was low (0.037). Further analysis of a 173-sample subset by nested PCR of small subunit ribosomal DNA resulted in an overall 3.0-fold increase in prevalence of infection, with a 17.5-fold increase in the frequency of mixed species infections. Among mixed species infections detected by PCR, the frequency of double species was 0.364, and that of triple species was 0.237. Nine individuals (0.052) were infected with all 4 species. To determine if infection status (uninfected, single, and multiple infections) deviates from an independent random distribution (null hypothesis), observed versus expected frequencies of all combinations of Plasmodium species infections, or assemblages (Pf-, Pv-, Pm-, Po-, to Pf+, Pv+, Pm+, Po+), were compared using a multiple-kind lottery model. All 4 species were randomly distributed whether diagnosed by blood smear or PCR in the overall population and when divided into age group categories. These findings suggest that mixed species malaria infections are common, and that Plasmodium species appear to establish infection independent of one another.

Resistance to replication of human immunodeficiency virus challenge in SCID-Hu mice engrafted with peripheral blood mononuclear cells of nonprogressors is mediated by CD8(+) T cells and associated with a proliferative response to p24 antigen

High levels of resistance to challenge with human immunodeficiency virus type 1 SF162 were observed in animals engrafted with peripheral blood mononuclear cells of four long-term nonprogressors (LTNPs). Resistance was abrogated by depletion of CD8(+) T cells in vivo and was observed only in LTNPs with proliferative responses to p24. In a subgroup of nonprogressors, CD8(+) T cells mediated restriction of challenge viruses, and this response was associated with strong proliferative responses to p24 antigen.

Emergence of FY*A(null) in a Plasmodium vivax-endemic region of Papua New Guinea

In Papua New Guinea (PNG), numerous blood group polymorphisms and hemoglobinopathies characterize the human population. Human genetic polymorphisms of this nature are common in malarious regions, and all four human malaria parasites are holoendemic below 1500 meters in PNG. At this elevation, a prominent condition characterizing Melanesians is alpha(+)-thalassemia. Interestingly, recent epidemiological surveys have demonstrated that alpha(+)-thalassemia is associated with increased susceptibility to uncomplicated malaria among young children. It is further proposed that alpha(+)-thalassemia may facilitate so-called "benign" Plasmodium vivax infection to act later in life as a "natural vaccine" against severe Plasmodium falciparum malaria. Here, in a P. vivax-endemic region of PNG where the resident Abelam-speaking population is characterized by a frequency of alpha(+)-thalassemia >/=0.98, we have discovered the mutation responsible for erythrocyte Duffy antigen-negativity (Fy[a-b-]) on the FY*A allele. In this study population there were 23 heterozygous and no homozygous individuals bearing this new allele (allele frequency, 23/1062 = 0.022). Flow cytometric analysis illustrated a 2-fold difference in erythroid-specific Fy-antigen expression between heterozygous (FY*A/FY*A(null)) and homozygous (FY*A/FY*A) individuals, suggesting a gene-dosage effect. In further comparisons, we observed a higher prevalence of P. vivax infection in FY*A/FY*A (83/508 = 0.163) compared with FY*A/FY*A(null) (2/23 = 0.087) individuals (odds ratio = 2.05, 95% confidence interval = 0.47-8.91). Emergence of FY*A(null) in this population suggests that P. vivax is involved in selection of this erythroid polymorphism. This mutation would ultimately compromise alpha(+)-thalassemia/P. vivax-mediated protection against severe P. falciparum malaria.

[Variations under genetic control of onchocerca infection as a function of clinical profile in the endemic center of Cameroon]

Onchocerciasis, also known as "river blindness", presents a plenum of clinical manifestations which vary from one individual to another, and from one area to another. This large spectrum of clinical manifestations of the disease is an indication of the complexity of the pathogenesis of onchocerciasis and suggests that many interacting factors might influence the clinical features of the disease. The present study has focused on the heterogenicity of the host immune response as a plausible explanation for differences in clinical manifestations of the infection. Host genetic factors, namely HLA genes, might play an important role in determining the nature of the immune response mounted against the parasite Onchocerca volvulus, and thus the development of different manifestations of the infection. Genetic diversity of onchocerciasis was assessed in different endemic foci in Cameroon. In order to investigate the possibility that the Major Histocompatibility Complex (MHC) genes might be associated with the different clinical types of onchocerciasis, 146 subjects living in three endemic areas of Cameroon were studied. They were classified in four groups: A (asymptomatic subjects), P (putatively immune subjects) L (patients with localised disease) and G (patients with generalised disease). The four groups differed in the distribution of HLA class II alleles as determined by Direct Heteroduplex Analysis. On the one hand, allele HLA-DQA1*0501 appeared to be associated with protection against severe onchocerciasis; on the other, allele HLA-DQB1*0201 might play an important role in the severe form of the disease.

Epidemiologic and biologic characterization of a cohort of human immunodeficiency virus type 1 highly exposed, persistently seronegative female sex workers in northern Thailand. Chiang Mai HEPS Working Group

Characterization of persons highly exposed to human immunodeficiency virus (HIV)-1 who remain uninfected may help define protective immunity. Seventeen HIV-1-seronegative Thai female sex workers (CSWs) with epidemiologic evidence of exposure to HIV-1 were studied for humoral immune responses and phenotypic and genotypic analyses of HLA class I and CCR5 allelic profiles. Infected CSWs and low-risk HIV-1-seronegative Thai women were controls. Highly exposed, persistently seronegative (HEPS) CSWs did not differ from HIV-infected CSWs in HIV risks, condom use, or sexually transmitted diseases. Significant differences were seen in humoral immune responses: gp160-specific IgA responses were detected in cervicovaginal lavage fluids in 6 of 13 HEPS CSWs but 0 of 21 seronegative subjects. All women had wild-type CCR5. HEPS CSWs were more likely to have the HLA-B18 phenotype and genotype than were matched controls (corrected P=.018). Epidemiologic exposure to HIV-1 without apparent infection, an unusual distribution of HLA class I alleles, and HIV-1 gp160-specific IgA responses suggest a biologic basis for this phenomenon.

Familial eosinophilia maps to the cytokine gene cluster on human chromosomal region 5q31-q33

Familial eosinophilia (FE) is an autosomal dominant disorder characterized by peripheral hypereosinophilia of unidentifiable cause with or without other organ involvement. To localize the gene for FE, we performed a genomewide search in a large U.S. kindred, using 312 different polymorphic markers. Seventeen affected subjects, 28 unaffected bloodline relatives, and 8 spouses were genotyped. The initial linkage results from the genome scan provided evidence for linkage on chromosome 5q31-q33. Additional genotyping of genetic markers located in this specific region demonstrated significant evidence that the FE locus is situated between the chromosome 5q markers D5S642 and D5S816 (multipoint LOD score of 6.49). Notably, this region contains the cytokine gene cluster, which includes three genes-namely, those for interleukin (IL)-3, IL-5, and granulocyte/macrophage colony-stimulating factor (GM-CSF)-whose products play important roles in the development and proliferation of eosinophils. These three cytokine genes were screened for potential disease-specific mutations by resequencing of a subgroup of individuals from the present kindred. No functional sequence polymorphisms were found within the promoter, the exons, or the introns of any of these genes or within the IL-3/GM-CSF enhancer, suggesting that the primary defect in FE is not caused by a mutation in any one of these genes but, rather, is caused by another gene in the area.