Association between genital schistosomiasis and HIV in rural Zimbabwean women

Helminth infections: a new global women's health agenda

Emerging evidence over the past decade has implicated helminth infections as important yet stealth causes of adverse pregnancy outcomes and impaired women's reproductive health. The two most important helminth infections affecting women living in poverty in Africa and elsewhere in the developing world are hookworm infection and schistosomiasis. In Africa alone, almost 40 million women of childbearing age are infected with hookworms, including almost 7 million pregnant women who are at greater risk of severe anemia, higher mortality, and experiencing poor neonatal outcome (reduced birth weight and increased infant mortality). Possibly, tens of millions of women in Africa also suffer from female genital schistosomiasis associated with genital itching and pain, stress incontinence, dyspareunia, and infertility and experience social stigma and depression. Female genital schistosomiasis also is linked to horizontal transmission of human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) and it may represent one of Africa's major cofactors in its AIDS epidemic. There is urgency to expand mass drug administration efforts for hookworm and schistosomiasis to include women of reproductive age and to shape new policies and advocacy initiatives for women's global health to include helminth control. In parallel is a requirement to better link global health programs for HIV and AIDS and malaria with helminth control and to simultaneously launch initiatives for research and development.

Genital schistosomiasis and its unacknowledged role on HIV transmission in the STD intervention studies

Treatment of sexually transmitted infections (STIs) has been hypothesised to decrease HIV transmission. Although observational studies show an association between STIs and HIV, only one prospective randomised controlled trial (RCT) has confirmed this. Female genital schistosomiasis can cause genital lesions, accompanied by bloody discharge, ulcers or malodorous discharge. Genital schistosomiasis is common, starts before puberty and symptoms can be mistaken for STIs. Three observational studies have found an association between schistosomiasis and HIV. Genital lesions that develop in childhood are chronic. This paper sought to explore the possible effects of schistosomiasis on the RCTs of STI treatment for HIV prevention.

In the study sites, schistosomiasis was a likely cause of genital lesions. The studies recruited women that may have had genital schistosomal lesions established in childhood. Schistosomiasis endemic areas with different prevalence levels may have influenced HIV incidence in intervention and control sites differently, and some control group interventions may have influenced the impact of schistosomiasis on the study results. Schistosomiasis is a neglected cause of genital tract disease. It may have been an independent cause of HIV incidence in the RCTs of STI treatment for HIV prevention and may have obscured the findings of these trials.

Dosing of praziquantel by height in sub-Saharan African adults

The cornerstone of schistosomiasis control is mass praziquantel treatment in high prevalence areas. Adults are an important target population, given increasing recognition of the burden of male and female genital schistosomiasis. However, use of weighing scales to calculate praziquantel dosing in rural areas can be challenging. For school-age children, the World Health Organization (WHO) has approved a dose pole to simplify praziquantel dosing based on height. We modified the pediatric dose pole by adding two height categories and incorporating a simple overweight/obesity adjustment, for simplified mass treatment of adults in sub-Saharan Africa. Using the rural Zimbabwean Demographic and Health Survey data, we show that the modified dose pole with body mass index adjustment would result in > 98% of adults receiving an acceptable dose (30-60 mg/kg), with only 1.4% and 0.3% receiving an inadequate dose (< 30 mg/kg) or high dose (> 60 mg/kg), respectively. An adult dose pole may provide a more feasible alternative to weighing scales in community-based praziquantel treatment programs.

Immunology of pediatric HIV infection

Most infants born to human immunodeficiency virus (HIV)-infected women escape HIV infection. Infants evade infection despite an immature immune system and, in the case of breastfeeding, prolonged repetitive exposure. If infants become infected, the course of their infection and response to treatment differs dramatically depending upon the timing (in utero, intrapartum, or during breastfeeding) and potentially the route of their infection. Perinatally acquired HIV infection occurs during a critical window of immune development. HIV's perturbation of this dynamic process may account for the striking age-dependent differences in HIV disease progression. HIV infection also profoundly disrupts the maternal immune system upon which infants rely for protection and immune instruction. Therefore, it is not surprising that infants who escape HIV infection still suffer adverse effects. In this review, we highlight the unique aspects of pediatric HIV transmission and pathogenesis with a focus on mechanisms by which HIV infection during immune ontogeny may allow discovery of key elements for protection and control from HIV.

Study participants incentives, compensation and reimbursement in resource-constrained settings

INTRODUCTION

Controversies still exists within the research fraternity on the form and level of incentives, compensation and reimbursement to study participants in resource-constrained settings. While most research activities contribute significantly to advancement of mankind, little has been considered in rewarding directly the research participants from resource-constrained areas.

METHODS

A study was conducted in Zimbabwe to investigate views and expectations of various stakeholders on study participation incentives, compensation and reimbursement issues. Data was collected using various methods including a survey of about 1,008 parents/guardians of school children participating in various immunological cohort studies and parasitology surveys. Community advisory boards (CABs) at 9 of the sites were also consulted. Further, information was gathered during discussions held at a basic research ethics training workshop. The workshop had 45 participants that including 40 seasoned Zimbabwean researchers and 5 international research collaborators.

RESULTS

About 90% (907) of the study participants and guardians expected compensation of reasonable value, in view of the researchers' value and comparison to other sites regardless of economic status of the community. During discussion with researchers at a basic ethics training workshop, about 80% (32) believed that decisions on level of compensation should be determined by the local research ethics committees. While, the few international research collaborators were of the opinion that compensation should be in accordance with local guidelines, and incentives should be in line with funding. Both the CAB members and study participants expressed that there should be a clear distinction between study incentive and compensation accorded to individual and community expectations on benefits from studies. However, CABs expressed that their suggestions on incentives and compensation are often moderated by the regulatory authorities who cite fear of unknown concerns.

CONCLUSION

Overall, both personal and community benefits need to be considered collectively in future studies to be conducted in resource-constrained communities. There is projected fear that recruitment in future may be a challenge, now that almost every community, has somehow been reached and participated in some form of studies. A major concern on reimbursement, compensation or incentives should be internationally pegged regardless of different economic status of the individuals or communities where the study is to be conducted.

Effect of helminth-induced immunity on infections with microbial pathogens

Helminth infections are ubiquitous worldwide and can trigger potent immune responses that differ from and potentially antagonize host protective responses to microbial pathogens. In this Review we focus on the three main killers in infectious disease-AIDS, tuberculosis and malaria-and critically assesses whether helminths adversely influence host control of these diseases. We also discuss emerging concepts for how M2 macrophages and helminth-modulated dendritic cells can potentially influence the protective immune response to concurrent infections. Finally, we present evidence advocating for more efforts to determine how and to what extent helminths interfere with the successful control of specific concurrent coinfections.

Urogenital schistosomiasis in women of reproductive age and pregnant mothers in Kwale County, Kenya

Generally, women residing in areas endemic for urinary schistosomiasis may suffer from female genital schistosomiasis which is acquired during childhood. The objective of this cross-sectional study was to estimate the prevalence and intensity of infection of Schistosoma haematobium in women of reproductive age (16-45 years) and to investigate whether S. haematobium had any effect on kidney function. A total of 394 women of known pregnancy status (158 pregnant and 236 non-pregnant) were recruited from five villages (known for their high prevalence of infection of S. haematobium) in Kwale County. Serum samples were analysed to determine levels of urea and creatinine as proxy indicators of kidney function. Data revealed that pregnant women did not, on average, have a higher prevalence or intensity of infection of urinary schistosomiasis than non-pregnant women. During pregnancy, the level of prevalence and intensity of infection of S. haematobium was highest in the first trimester (0-13 weeks), dropped in the second trimester (14-26 weeks) and rose again in the third trimester (27-40 weeks). In addition, 24.8% of women were infected with hookworm, while none were diagnosed with malaria parasites. Of 250 samples analysed for serum urea and creatinine, none had significant levels of pathology, either in pregnant or non-pregnant women. Despite World Health Organization (WHO) recommendations that pregnant women should be treated with praziquantel after the first trimester, in practice this has not been the case in many countries, including Kenya. In view of this, healthcare providers should be informed to consider treatment of pregnant women infected with schistosomiasis during antenatal visits and whenever there is mass drug administration as recommended by the WHO.

Seroprevalence of Schistosomiasis and Strongyloides infection in HIV-infected patients from endemic areas attending a European infectious diseases clinic

Background

Although the Centres for disease Control and Prevention (CDC) recommends empiric treatment for schistosomiasis and strongyloidiasis (prevalent but treatable parasitic infections) in some refugee groups it is unclear if these guidelines should be extended to non-refugee immigrants from endemic areas. We aimed to assess seroprevalence of, and risk factors for, positive schistosomiasis and strongyloides serology in HIV-infected patients from endemic areas attending a European Infectious Diseases clinic.

Methods

In a prospective cohort study, HIV-infected patients from helminth endemic areas underwent clinical assessment and blood draw for schistosomiasis and strongyloides serology, routine haematology and inflammatory markers (ESR and CRP). Between-group differences were analyzed by Wilcoxin Signed Rank and Fisher’s t tests as appropriate.

Results

Ninety HIV-infected patients (mean [standard deviation (SD)] age 34 [6] years, 29% male) were recruited from May 2008 to June 2009. Nine (10%) subjects tested positive for helminth infections. Seven tested positive for schistosomiasis (8%) while two tested positive for strongyloides (2%). Seropositive subjects were more likely to have higher eosinophil counts (mean [SD]) (0.3 [0.3] vs. 0.15 [0.2] x10³cells/cm, P = 0.021) with a trend towards lower CD4+ T-cell counts (mean [SD]) (280 [218] vs. 395 [217] cells/mm³, P = 0.08).

Conclusion

The high prevalence of helminth infections (10%) in asymptomatic HIV infected adults identified in this study supports routine screening of immigrants from helminth endemic areas or with exposure history.

Detectable urogenital schistosome DNA and cervical abnormalities 6 months after single-dose praziquantel in women with Schistosoma haematobium infection

We explored response to single-dose praziquantel therapy in a cohort of 33 women with Schistosoma haematobium infection in rural Mwanza, Tanzania. Women with S. haematobium infection confirmed both by eggs in urine and by polymerase chain reaction (PCR) received single-dose praziquantel and treatment of concomitant sexually transmitted infections. Macroscopic cervical abnormalities were also quantified. After 6 months, microscopically detectable egg excretion was eliminated, but 8 of 33 women (24%) were persistently positive for S. haematobium by PCR, and 11 (33%) had cervical abnormalities potentially attributable to schistosomiasis. This suggests that praziquantel treatment more frequently than every 6 months may be necessary for complete elimination of the parasite and prevention of genital tissue pathology. This aggressive therapy may in turn play a key role decreasing HIV susceptibility in millions of people living in regions in which S. haematobium is endemic.

HIV and Schistosoma haematobium prevalences correlate in sub-Saharan Africa

OBJECTIVE

Epidemiological studies have observed that genital schistosomiasis increases the risk of HIV infection in Africa. We analysed the correlation between Schistosoma haematobium prevalence and HIV prevalence across sub-Saharan African countries.

DESIGN

Regression analysis of prevalence of HIV and S. haematobium across sub-Saharan African countries.

METHODS

Using compiled country-level S. haematobium prevalence, HIV prevalence and other demographic and economic data from published sources, we applied univariate and multivariate regression models to assess the correlations between S. haematobium prevalence and HIV prevalence while controlling for risk factors associated with each infection.

RESULTS

In 43 sub-Saharan African countries, the mean prevalence of S. haematobium was 22.4% [standard deviation (SD): 9.8%] and for HIV was 6.21% (SD: 5.71%). In multivariate analysis, adjusted for prevalence of male circumcision, years since a country's first HIV/AIDS diagnosis, geographical region and immunization coverage, each S. haematobium infection per 100 individuals was associated with a 2.9% (95% CI: 0.2-5.8%) relative increase in HIV prevalence. S. haematobium was not associated with Schistosoma mansoni, HSV-2, hepatitis C, malaria or syphilis.

CONCLUSIONS

Schistosoma haematobium prevalence was associated with HIV prevalence in sub-Saharan Africa. Controlling S. haematobium may be an effective means of reducing HIV transmission in sub-Saharan Africa.

Potential cost-effectiveness of schistosomiasis treatment for reducing HIV transmission in Africa--the case of Zimbabwean women

Background

Epidemiological data from Zimbabwe suggests that genital infection with Schistosoma haematobium may increase the risk of HIV infection in young women. Therefore, the treatment of Schistosoma haematobium with praziquantel could be a potential strategy for reducing HIV infection. Here we assess the potential cost-effectiveness of praziquantel as a novel intervention strategy against HIV infection.

Methods

We developed a mathematical model of female genital schistosomiasis (FGS) and HIV infections in Zimbabwe that we fitted to cross-sectional data of FGS and HIV prevalence of 1999. We validated our epidemic projections using antenatal clinic data on HIV prevalence. We simulated annual praziquantel administration to school-age children. We then used these model predictions to perform a cost-effectiveness analysis of annual administration of praziquantel as a potential measure to reduce the burden of HIV in sub-Saharan Africa.

Findings

We showed that for a variation of efficacy between 30–70% of mass praziquantel administration for reducing the enhanced risk of HIV transmission per sexual act due to FGS, annual administration of praziquantel to school-age children in Zimbabwe could result in net savings of US$16–101 million compared with no mass treatment of schistosomiasis over a ten-year period. For a variation in efficacy between 30–70% of mass praziquantel administration for reducing the acquisition of FGS, annual administration of praziquantel to school-age children could result in net savings of US$36−92 million over a ten-year period.

Conclusions

In addition to reducing schistosomiasis burden, mass praziquantel administration may be a highly cost-effective way of reducing HIV infections in sub-Saharan Africa. Program costs per case of HIV averted are similar to, and under some conditions much better than, other interventions that are currently implemented in Africa to reduce HIV transmission. As a cost-saving strategy, mass praziquantel administration should be prioritized over other less cost-effective public health interventions.

Evidence from epidemiological and clinical studies supports the hypothesis that genital infection with Schistosoma haematobium increases the risk of becoming infected with HIV among women in sub-Saharan Africa. Praziquantel is an oral, nontoxic, inexpensive medication recommended for treatment of schistosomiasis, which might be able to prevent the development of genital schistosomiasis. We constructed a mathematical model of female genital schistosomiasis and HIV infections, which we calibrated using epidemiological data from Zimbabwe. We used this model to investigate the potential cost-effectiveness of mass drug administration with praziquantel as an intervention strategy for reducing HIV transmission in sub-Saharan Africa. We showed that mass drug administration with praziquantel may be a timely, innovative, and cost-saving intervention strategy for HIV prevention in sub-Saharan Africa. As a cost-saving strategy, mass drug administration with praziquantel should be prioritized over other less cost-effective public health interventions. Our findings indicate the possible benefit of scaling up schistosomiasis control efforts in sub-Saharan Africa, and especially in areas were Schistosoma haematobium and HIV are highly prevalent.

Pathologic mucosal blood vessels in active female genital schistosomiasis: new aspects of a neglected tropical disease

Female genital schistosomiasis is a frequent, but neglected cause of mucosal pathology in the female genital tract. Moreover, recent studies indicate that genital mucosal lesions may increase the risk of human immunodeficiency virus (HIV) infection. In rural Africa, detailed clinical images are rarely available alongside histologic sections, and further understanding of the pathogenesis of the genital mucosal lesions is needed. These cases represent previously unreported histopathologic photomicrographs and corresponding clinical images in 2 women with genital schistosomiasis. Dilated and tortuous mucosal venules seen in the cervicovaginal mucosa were found to contain viable Schistosoma haematobium eggs surrounded by a thrombus. The presence of abnormal mucosal blood vessels may be an indication of a persistent tissue reaction to S. haematobium ova in the lower female genital tract.

Cost-effectiveness of a community-based intervention for reducing the transmission of Schistosoma haematobium and HIV in Africa

Epidemiological studies from sub-Saharan Africa show that genital infection with Schistosoma haematobium [corrected] may increase the risk for HIV infection in young women. Therefore, preventing schistosomiasis has the potential to reduce HIV transmission in sub-Saharan Africa. We developed a transmission model of female genital schistosomiasis and HIV infections that we fit to epidemiological data of HIV and female genital schistosomiasis prevalence and coinfection in rural Zimbabwe. We used the model to evaluate the cost-effectiveness of a multifaceted community-based intervention for preventing schistosomiasis and, consequently, HIV infections in rural Zimbabwe, from the perspective of a health payer. The community-based intervention combined provision of clean water, sanitation, and health education (WSH) with administration of praziquantel to school-aged children. Considering variation in efficacy between 10% and 70% of WSH for reducing S. haematobium [corrected] transmission, our model predicted that community-based intervention is likely to be cost-effective in Zimbabwe at an aggregated WSH cost corresponding to US $725-$1,000 per individual over a 20-y intervention period. These costs compare favorably with empirical measures of WSH provision in developing countries, indicating that integrated community-based intervention for reducing the transmission of S. haematobium [corrected] is an economically attractive strategy for reducing schistosomiasis and HIV transmission in sub-Saharan Africa that would have a powerful impact on averting infections and saving lives.

S. haematobium as a common cause of genital morbidity in girls: a cross-sectional study of children in South Africa

Background

Schistosoma (S.) haematobium infection is a common cause of genital morbidity in adult women. Ova in the genital mucosal lining may cause lesions, bleeding, pain, discharge, and the damaged surfaces may pose a risk for HIV. In a heterogeneous schistosomiasis endemic area in South Africa, we sought to investigate if young girls had genital symptoms and if this was associated with urinary S. haematobium.

Methodology

In a cross-sectional study of 18 randomly chosen primary schools, we included 1057 schoolgirls between the age of 10 and 12 years. We interviewed assenting girls, whose parents had consented to their participation and examined three urines from each of them for schistosome ova.

Principal findings

One third of the girls reported to have a history of genital symptoms. Prior schistosomal infection was reported by 22% (226/1020), this was associated with current genital symptoms (p<0.001). In regression analysis the genital symptoms were significantly associated both with urinary schistosomiasis (p<0.001) and water contact (p<0.001).

Conclusions

Even before sexually active age, a relatively large proportion of the participating girls had similar genital symptoms to those reported for adult genital schistosomiasis previously. Anti-schistosomal treatment should be considered at a young age in order to prevent chronic genital damage and secondary infections such as HIV, sexually transmitted diseases and other super-infections.

Urogenital schistosomiasis (Bilharzia) is a common cause of gynecological disease in adult women. Reports to date indicate that genital lesions in adults become chronic and that the damages make women susceptible to HIV. This is the first study on urogenital schistosomiasis in pre-pubertal girls. We interviewed girls aged 10 to 12 years of age for urinary and gynecological symptoms. The research assistants did not know the schistosomiasis infection status in the school or the individuals. We collected three urines that were examined for schistosome eggs. We found that a significantly increased number of girls with urinary schistosomiasis have stinking, bloody discharge, ulcers, tumors and a burning sensation in their genitals. This indicates that gynecological damages due to schistosomiasis start before sexual activity, and before menstruation. By preventing urogenital schistosomiasis in girls we may have an innovative opportunity to reduce teenage HIV transmission and gynecological disease. This study presents a new aspect of a neglected disease affecting more than 100 million females, long overdue for mass intervention.

Measuring and modelling concurrency

This article explores three critical topics discussed in the recent debate over concurrency (overlapping sexual partnerships): measurement of the prevalence of concurrency, mathematical modelling of concurrency and HIV epidemic dynamics, and measuring the correlation between HIV and concurrency. The focus of the article is the concurrency hypothesis - the proposition that presumed high prevalence of concurrency explains sub-Saharan Africa's exceptionally high HIV prevalence. Recent surveys using improved questionnaire design show reported concurrency ranging from 0.8% to 7.6% in the region. Even after adjusting for plausible levels of reporting errors, appropriately parameterized sexual network models of HIV epidemics do not generate sustainable epidemic trajectories (avoid epidemic extinction) at levels of concurrency found in recent surveys in sub-Saharan Africa. Efforts to support the concurrency hypothesis with a statistical correlation between HIV incidence and concurrency prevalence are not yet successful. Two decades of efforts to find evidence in support of the concurrency hypothesis have failed to build a convincing case.

Strongyloides stercoralis disseminated infection and schistosomiasis in an AIDS patient

Strongyloides stercoralis hyperinfection syndrome is classically associated with impaired host response and implies in an overburden of larvae in its usual cycle. It has been recognized as a severe and potentially fatal condition in immunocompromised individuals, especially those using oral corticosteroids. Infection with Schistosoma mansoni not only increases the susceptibility to HIV infection, but also promotes progression to disease. The association of the most severe forms of strongyloidiasis and AIDS is scarcely described, even more when S. mansoni is also associated. The authors describe a case of a 34-year-old previously healthy male, admitted to the emergency department with a history of hematemesis associated with dyspnea, hemoptysis, and fever. He referred homosexual relations for 6 years. Physical examination showed an ill-looking patient, and was remarkable for tachycardia, tachypnea, diaphoresis, and pulse oximetry of 70% in room air. Lungs examination revealed the presence of rales in the left base. Chest radiography showed a diffuse and bilateral reticulo-nodular pattern. HIV serology was positive. Empirical antimicrobial therapy and corticosteroids were initiated. On the third day of hospitalization, petechiae appeared over the periumbilical area, but no further investigation was undertaken because the patient died soon after. The autopsy findings were compatible with S. stercoralis disseminated infection, a hepatic intestinal chronic form of schistosomiasis, and septic shock as the primary cause of death. The authors call attention to this infrequent association.

Efficacy of mefloquine intermittent preventive treatment in pregnancy against Schistosoma haematobium infection in Gabon: a nested randomized controlled assessor-blinded clinical trial

BACKGROUND

Urogenital schistosomiasis is a major public health problem in sub-Saharan Africa, and routine programs for screening and treatment of pregnant women are not established. Mefloquine-currently evaluated as a potential alternative to sulfadoxine-pyrimethamine as intermittent preventive treatment against malaria in pregnancy (IPTp)-is known to exhibit activity against Schistosoma haematobium. In this study we evaluated the efficacy of mefloquine IPTp against S. haematobium infection in pregnant women.

METHODS

Pregnant women with S. haematobium infection presenting at 2 antenatal health care centers in rural Gabon were invited to participate in this nested randomized controlled, assessor-blinded clinical trial comparing sulfadoxine-pyrimethamine with mefloquine IPTp. Study drugs were administered twice during pregnancy with a 1- month interval after completion of the first trimester.

RESULTS

Sixty-five pregnant women were included in this study. Schistosoma haematobium egg excretion rates showed a median reduction of 98% (interquartile range [IQR], 70%-100%) in the mefloquine group compared to an increase of 20% (IQR, -186% to 75%) in the comparator group. More than 80% of patients showed at least 50% reduction of egg excretion and overall cure rate was 47% (IQR, 36%-70%) 6 weeks after the second administration of mefloquine IPTp.

CONCLUSION

When used as IPTp for the prevention of malaria, mefloquine shows promising activity against concomitant S. haematobium infection leading to an important reduction of egg excretion in pregnant women. Provided that further studies confirm these findings, the use of mefloquine may transform future IPTp programs into a 2-pronged intervention addressing 2 of the most virulent parasitic infections in pregnant women in sub-Saharan Africa.

CLINICAL TRIALS REGISTRATION

NCT01132248; ATMR2010020001429343.

Epidemiology and immunology of helminth-HIV interactions

PURPOSE OF REVIEW

Helminths and HIV-1 use multiple mechanisms to avoid or deviate immune responses, and these mechanisms may interact with important consequences for the epidemiology of each infection. In this review, we summarize recent immunological and epidemiological advances in the understanding of HIV-1-helminth co-infections.

RECENT FINDINGS

Considering the extent of geographical overlap of these chronic infections, there has been so far surprisingly limited and inconsistent evidence of important interactive effects, either from epidemiological studies examining associations between helminth infection indicators and HIV disease parameters, or from studies that have dissected the immune mechanisms triggered by each pathogen in isolation and investigated their interaction. Systematic reviews have found inconsistent evidence for a beneficial effect of anthelmintic treatment of helminth-HIV-1 co-infected individuals on viral load or CD4 cell counts. It is not certain that co-infection with HIV-1 and helminths will always be more detrimental to the host than either single infection alone, or that intervening against co-infections will have only beneficial effects.

SUMMARY

A consensus on the implications of co-infection on de-worming and vaccination policies has not yet emerged. Well powered randomized trials in HIV-1-infected individuals with defined helminth infections are required to determine the benefits of anthelmintic interventions.

The effects of schistosomiasis on HIV/AIDS infection, progression and transmission

PURPOSE OF REVIEW

The recent findings pertaining to the public health impact of schistosomiasis on the epidemiology of HIV/AIDS are summarized.

RECENT FINDINGS

Both empiric data and mathematical models support the hypothesis that schistosome infections lead to increased susceptibility to infection with HIV-1, a more rapid progression to disease through more vigorous viral replication and immunosuppression, and a higher likelihood of transmitting the infection to others through both vertical and horizontal routes. Different species of schistosome infection vary in the magnitude of their effects on these mechanisms with Schistosoma haematobium playing a greater role for increased susceptibility and transmission because of its association with urogenital disease.

SUMMARY

Schistosomiasis appears to be a cofactor in the spread and progression of HIV/AIDS in areas wherein both diseases are endemic; increased emphasis on treatment of schistosome infections in persons at risk of HIV/AIDS should be pursued.

The effect of anthelmintic treatment during pregnancy on HIV plasma viral load: results from a randomized, double-blind, placebo-controlled trial in Uganda

BACKGROUND

To investigate the effect of helminth infections and their treatment during pregnancy on HIV load, we conducted a 2 × 2 factorial randomized controlled trial of albendazole versus placebo and praziquantel versus placebo in pregnant women in Entebbe, Uganda.

METHODS

Two hundred sixty-four HIV-infected pregnant women from the Entebbe Mother and Baby Study (ISRCTN 32849447) were included in this analysis. Women were tested for helminth infections at enrollment, and mean HIV load was compared between infected and uninfected groups. The effect of anthelmintic treatment on HIV load was evaluated at 6 weeks after treatment and at delivery using linear regression and adjusting for enrollment viral load.

RESULTS

Hookworm and Trichuris infections were associated with higher mean viral load at enrollment [adjusted mean difference 0.24 log10 copies/mL, 95% confidence interval (CI): 0.01 to 0.47, P = 0.03, and 0.37 log(10) copies/mL, 95% CI: 0.00 to 0.74, P = 0.05, respectively]. There were no associations between viral load and other helminth species. There was some evidence that albendazole reduced viral load at 6 weeks after treatment (adjusted mean difference -0.17, 95% CI: -0.36 to 0.01, P = 0.07); however, this effect did not differ according to mother's hookworm infection status and had diminished at delivery (adjusted mean difference -0.11, 95% CI: -0.28 to 0.07, P = 0.23). There was no effect of praziquantel treatment on HIV load at any time point.

CONCLUSIONS

Infection with some soil-transmitted helminth species is associated with increased HIV load in pregnancy. Treatment with albendazole causes a small decrease in HIV load; however, this may not represent a direct effect of worm removal.

Living with uncertainty

The persistence of highly endemic parasitic, bacterial and viral diseases makes individuals and populations vulnerable to emerging and re-emerging diseases. Evaluating the role of multiple component, often interacting, causes of disease may be impossible with research tools designed to isolate single causes. Similarly, it may not be possible to identify statistically significant treatment effects, even for interventions known to be effective, when multiple morbidities are present. Evidence continues to accumulate that nutritional deficiencies, bacterial, viral and parasitic coinfections accelerate HIV transmission. Inclusion of antiparasitics and other beneficial interventions in HIV-prevention protocols is impeded by reliance on inappropriate methodologies. Lack of full scientific certainty is not a reason for postponing safe, cost-effective measures to prevent irreversible damage.

Reversing the resistance phenotype of the Biomphalaria glabrata snail host Schistosoma mansoni infection by temperature modulation

Biomphalaria glabrata snails that display either resistant or susceptible phenotypes to the parasitic trematode, Schistosoma mansoni provide an invaluable resource towards elucidating the molecular basis of the snail-host/schistosome relationship. Previously, we showed that induction of stress genes either after heat-shock or parasite infection was a major feature distinguishing juvenile susceptible snails from their resistant counterparts. In order to examine this apparent association between heat stress and snail susceptibility, we investigated the effect of temperature modulation in the resistant snail stock, BS-90. Here, we show that, incubated for up to 4 hrs at 32°C prior to infection, these resistant snails became susceptible to infection, i.e. shedding cercariae at 5 weeks post exposure (PE) while unstressed resistant snails, as expected, remained resistant. This suggests that susceptibility to infection by this resistant snail phenotype is temperature-sensitive (ts). Additionally, resistant snails treated with the Hsp 90 specific inhibitor, geldanamycin (GA) after heat stress, were no longer susceptible to infection, retaining their resistant phenotype. Consistently, susceptible snail phenotypes treated with 100 mM GA before parasite exposure also remained uninfected. These results provide direct evidence for the induction of stress genes (heat shock proteins; Hsp 70, Hsp 90 and the reverse transcriptase [RT] domain of the nimbus non-LTR retrotransposon) in B. glabrata susceptibility to S. mansoni infection and characterize the resistant BS-90 snails as a temperature-sensitive phenotype. This study of reversing snail susceptibility phenotypes to S. mansoni provides an opportunity to directly track molecular pathway(s) that underlie the B. glabrata snail's ability to either sustain or destroy the S. mansoni parasite.

Biomphalaria glabrata snails that are either resistant or susceptible to the parasite, Schistosoma mansoni, have been an invaluable resource in studies aimed at understanding the molecular basis of the snail/schistosome interaction. Schistosomes cause the chronic debilitating disease schistosomiasis. Thus, it is hoped that dissecting pathways that underlie the snail/schistosome relationship might translate into alternative control strategies that will include blocking transmission of the parasite at the snail-stage of its development. Induction of stress genes is a feature distinguishing early exposed juvenile susceptible NMRI snails from resistant BS-90 snail stocks. To further analyze this apparent involvement of stress induction and snail susceptibility, here we applied heat stress to the resistant BS-90 snail, enhancing induction of stress genes (Hsp 70, Hsp 90 and RT) prior to infection. Results showed these resistant snails became susceptible, indicating resistance as being a temperature sensitive phenotype in these snails. Stressed resistant snails treated with the Hsp 90 specific inhibitor, geldanamycin, prior to exposure, were, however, shown to maintain their refractory phenotype. Interestingly, inhibitor treated susceptible snails also became non-susceptible. Collectively, these data point to stress induction as an important early step in the ability of S. mansoni to infect juvenile B. glabrata snails.

Helminth parasite proteomics: from experimental models to human infections

Schistosomiasis is a major human helminth infection endemic in developing countries. Urogenital schistosomiasis, caused by S. haematobium, is the most prevalent human schistosome disease in sub-Saharan Africa. Currently control of schistosome infection is by treatment of infected people with the anthelmintic drug praziquantel, but there are calls for continued efforts to develop a vaccine against the parasites. In order for successful vaccine development, it is necessary to understand the biology and molecular characteristics of the parasite. Ultimately, there is need to understand the nature and dynamics of the relationship between the parasite and the natural host. Thus, my studies have focused on molecular characterization of different parasite stages and integrating this information with quantitative approaches to investigate the nature and development of protective immunity against schistosomes in humans. Proteomics has proved a powerful tool in these studies allowing the proteins expressed by the parasite to be characterized at a molecular and immunological level. In this review, the application of proteomic approaches to understanding the human-schistosome relationship as well as testing specific hypotheses on the nature and development of schistosome-specific immune responses is discussed. The contribution of these approaches to informing schistosome vaccine development is highlighted.

Guidelines on the treatment of chronic coinfection by Trypanosoma cruzi and HIV outside endemic areas

As a result of population migration, Chagas disease is no longer limited to the North and South American continents. In HIV-infected patients, chronic infection by Trypanosoma cruzi behaves as an opportunistic infection in severely immunosuppressed patients and is responsible for high morbidity and mortality. Unlike other opportunistic infections, information on the natural history, diagnosis, treatment, and prevention of Chagas disease is scarce. Spain has the highest number of cases of Chagas disease outside the North and South American continents, and coinfection with HIV is increasingly prevalent. In this article, the Spanish Society for Tropical Medicine and International Health (Sociedad Española de Medicina Tropical y Salud Internacional) reviews the current situation of coinfection with HIV and T. cruzi infection and provides guidelines on the diagnosis, treatment, and prevention in areas where Chagas disease is not endemic. It also identifies areas of uncertainty where additional research is necessary.

Co-infection of HIV and tropical infectious agents that affect the nervous system

Tropical infections refer to a group of diseases usually located in regions with a warm climate, particularly affecting developing countries, partly because of the conditions that allow them to thrive. However, due to the increased international travel, infectious agents that were previously limited to tropical regions pose an increasing threat to populations at risk for opportunistic infection (OI), especially those infected with the HIV. Tropical infections can facilitate HIV transmission and accelerate the progression of asymptomatic HIV infection to AIDS. Some have the potential to alter the epidemiology, natural history, and/or response to treatment of the other. The introduction of highly active antiretroviral therapy has provided a huge benefit for the vast majority of patients infected with the HIV, by allowing the immune system to recover, improving the clinical and radiological results and reducing the number of OI. On the other hand, some patients have developed various disorders of immune reconstitution, resulting in either hyper-immune inflammatory response to an exogenous antigen or autoimmunity. A significant proportion of these cases have been reported in immigrants from tropical countries to high-income countries, therefore awareness of these phenomena is needed since clinical presentations are often atypical and pose diagnostic challenges. This article reviews some of the key diagnostic aspects of tropical infections associated with HIV infection.

HIV target cells in Schistosoma haematobium-infected female genital mucosa

The parasite Schistosoma haematobium frequently causes genital lesions in women and could increase the risk of human immunodeficiency virus (HIV) transmission. This study quantifies the HIV target cells in schistosome-infected female genital mucosa. Cervicovaginal biopsies with and without schistosomiasis were immunostained for quantification of CD4(+) T lymphocytes (CD3, CD8), macrophages (CD68), and dendritic Langerhans cells (S100 protein). We found significantly higher densities of genital mucosal CD4(+) T lymphocytes and macrophages surrounding schistosome ova compared with cervicovaginal mucosa without ova (P = 0.034 and P = 0.018, respectively). We found no increased density of Langerhans cells (P = 0.25). This study indicates that S. haematobium may significantly increase the density of HIV target cells (CD4(+) T lymphocytes and macrophages) in the female genitals, creating a beneficial setting for HIV transmission. Further studies are needed to confirm these findings and to evaluate the effect of anti-schistosomal treatment on female genital schistosomiasis.

MCR synthesis of praziquantel derivatives

Schistosomiasis, a high volume neglected tropical disease affecting more than 200 million people worldwide, can only be effectively treated by the tetrahydroisoquinoline drug praziquantel (PZQ). Herein, we describe an efficient approach to access PZQ derivatives by the Ugi 4-component reaction followed by the Pictet-Spengler reaction in a two-step, one-pot procedure. 30 novel PZQ derivatives are described based on the Ugi 4-component reaction and an X-ray structure of a novel derivative revealing different conformation compared with PZQ is discussed. Several analogues comparable in activity to the drug PZQ have been identified based on an in vitro Schistosoma mansoni worm viability assay.

Whole-genome sequence of Schistosoma haematobium

Schistosomiasis is a neglected tropical disease caused by blood flukes (genus Schistosoma; schistosomes) and affecting 200 million people worldwide. No vaccines are available, and treatment relies on one drug, praziquantel. Schistosoma haematobium has come into the spotlight as a major cause of urogenital disease, as an agent linked to bladder cancer and as a predisposing factor for HIV/AIDS. The parasite is transmitted to humans from freshwater snails. Worms dwell in blood vessels and release eggs that become embedded in the bladder wall to elicit chronic immune-mediated disease and induce squamous cell carcinoma. Here we sequenced the 385-Mb genome of S. haematobium using Illumina-based technology at 74-fold coverage and compared it to sequences from related parasites. We included genome annotation based on function, gene ontology, networking and pathway mapping. This genome now provides an unprecedented resource for many fundamental research areas and shows great promise for the design of new disease interventions.

Neglected tropical diseases and the millennium development goals: why the "other diseases" matter: reality versus rhetoric

Since 2004 there has been an increased recognition of the importance of Neglected Tropical Diseases (NTDs) as impediments to development. These diseases are caused by a variety of infectious agents - viruses, bacteria and parasites - which cause a diversity of clinical conditions throughout the tropics. The World Health Organisation (WHO) has defined seventeen of these conditions as core NTDs. The objectives for the control, elimination or eradication of these conditions have been defined in World Health Assembly resolutions whilst the strategies for the control or elimination of individual diseases have been defined in various WHO documents. Since 2005 there has been a drive for the expanded control of these diseases through an integrated approach of mass drug administration referred to as Preventive Chemotherapy via community-based distribution systems and through schools. This has been made possible by donations from major pharmaceutical companies of quality and efficacious drugs which have a proven track record of safety. As a result of the increased commitment of endemic countries, bilateral donors and non-governmental development organisations, there has been a considerable expansion of mass drug administration. In particular, programmes targeting lymphatic filariasis, onchocerciasis, schistosomiasis, trachoma and soil transmitted helminth infections have expanded to treat 887. 8 million people in 2009. There has been significant progress towards guinea worm eradication, and the control of leprosy and human African trypanosomiasis. This paper responds to what the authors believe are inappropriate criticisms of these programmes and counters accusations of the motives of partners made in recently published papers. We provide a detailed response and update the information on the numbers of global treatments undertaken for NTDs and list the success stories to date.The paper acknowledges that in undertaking any health programme in environments such as post-conflict countries, there are always challenges. It is also recognised that NTD control must always be undertaken within the health system context. However, it is important to emphasise that the availability of donated drugs, the multiple impact of those drugs, the willingness of countries to undertake their distribution, thereby committing their own resources to the programmes, and the proven beneficial results outweigh the problems which are faced in environments where communities are often beyond the reach of health services. Given the availability of these interventions, their cost effectiveness and the broader development impact we believe it would be unethical not to continue programmes of such long term benefit to the "bottom billion".

Examining the relationship between urogenital schistosomiasis and HIV infection

Background

Urogenital schistosomiasis, caused by infection with Schistosoma haematobium, is widespread and causes substantial morbidity on the African continent. The infection has been suggested as an unrecognized risk factor for incident HIV infection. Current guidelines recommend preventive chemotherapy, using praziquantel as a public health tool, to avert morbidity due to schistosomiasis. In individuals of reproductive age, urogenital schistosomiasis remains highly prevalent and, likely, underdiagnosed. This comprehensive literature review was undertaken to examine the evidence for a cause-effect relationship between urogenital schistosomiasis and HIV/AIDS. The review aims to support discussions of urogenital schistosomiasis as a neglected yet urgent public health challenge.

Methodology/Principal Findings

We conducted a systematic search of the literature including online databases, clinical guidelines, and current medical textbooks. We describe plausible local and systemic mechanisms by which Schistosoma haematobium infection could increase the risk of HIV acquisition in both women and men. We also detail the effects of S. haematobium infection on the progression and transmissibility of HIV in co-infected individuals. We briefly summarize available evidence on the immunomodulatory effects of chronic schistosomiasis and the implications this might have for populations at high risk of both schistosomiasis and HIV.

Conclusions/Significance

Studies support the hypothesis that urogenital schistosomiasis in women and men constitutes a significant risk factor for HIV acquisition due both to local genital tract and global immunological effects. In those who become HIV-infected, schistosomal co-infection may accelerate HIV disease progression and facilitate viral transmission to sexual partners. Establishing effective prevention strategies using praziquantel, including better definition of treatment age, duration, and frequency of treatment for urogenital schistosomiasis, is an important public health priority. Our findings call attention to this pressing yet neglected public health issue and the potential added benefit of scaling up coverage of schistosomal treatment for populations in whom HIV infection is prevalent.

Urogenital schistosomiasis is a parasitic infection caused by a worm, Schistosoma haematobium, which lives in the bloodstream of infected individuals. It affects at least 112 million people, mostly in sub-Saharan Africa, and has been suggested to be a risk factor for becoming infected with HIV. We reviewed publications in order to examine whether it seems likely that this parasitic infection could be a risk factor for HIV. Evidence from many types of studies supports the hypothesis that urogenital schistosomiasis does increase a person's risk of becoming infected with HIV. Studies also suggest that individuals who have both urogenital schistosomiasis and HIV have a more aggressive HIV infection and can more easily transmit HIV to their sexual partners. Praziquantel is an oral, nontoxic, inexpensive medication that is safe in pregnancy and is recommended for treatment of schistosomiasis. In areas where both infections co-exist, regular administration of praziquantel both to young girls and to sexually-active women may be an important approach to reducing HIV transmission. Our findings support the importance of making praziquantel more available to people who live in areas of the world where both urogenital schistosomiasis and HIV infection are widespread.

MODELING THE EFFECTS OF SCHISTOSOMIASIS ON THE TRANSMISSION DYNAMICS OF HIV/AIDS

A schistosomiasis and HIV/AIDS co-infection model is presented as a system of nonlinear ordinary differential equations. Qualitative analysis (properties) of the model are presented. The disease-free equilibrium is shown to be locally asymptotically stable when the associated epidemic threshold known as the basic reproduction number for the model is less than unity. The Centre Manifold theory is used to show that the schistosomiasis only and HIV/AIDS only endemic equilibria are locally asymptotically stable when the associated reproduction numbers are greater than unity. The model is numerically analyzed to assess the effects of schistosomiasis on the dynamics of HIV/AIDS. Analysis of the reproduction numbers and numerical simulations show that an increase of schistosomiasis cases result in an increase of HIV/AIDS cases, suggesting that schistosomiasis control have a positive impact in controlling the transmission dynamics of HIV/AIDS.

Proportion of Urinary Schistosomiasis among HIV-Infected Subjects in Benin City, Nigeria

OBJECTIVES

This study aimed to determine the prevalence of urinary schistosomiasis, and the effect of CD4(+) T cell counts and demographics on its prevalence among HIV-positive patients in Benin City, Nigeria.

METHODS

Urine and blood samples were collected from 2000 HIV-positive subjects. A wet preparation of the urine deposit was examined microscopically to identify ova of Schistosoma haematobium. The blood specimens were analyzed using the flow cytometry for CD4 (+) T-lymphocyte count.

RESULTS

An overall prevalence rate of 0.3% was reported. Gender and CD4 count <200 cells/µL did not affect the prevalence of urinary schistosomiasis, while HIV patients that were single had significantly higher prevalence of urinary schistosomiasis (p=0.002).

CONCLUSION

The prevalence of urinary schistosomiasis among HIV patients in Benin City is low. CD4(+) count did not affect the prevalence of urinary schistosomiasis.

Schistosome: its benefit and harm in patients suffering from concomitant diseases

Schistosomiasis is an important tropical disease affecting approximately 200 million people worldwide. Because of its chronicity and robust immunomodulatory activity, the effects of schistosomes on other diseases, such as allergies, autoimmunity, and infectious diseases, have been studied extensively in both epidemiological and experimental settings. In this paper, we summarize the beneficial and harmful effects of schistosomes. The importance of controlling schistosomiasis is also discussed.

Genetic manipulation of Schistosoma haematobium, the neglected schistosome

Background

Minimal information on the genome and proteome of Schistosoma haematobium is available, in marked contrast to the situation with the other major species of human schistosomes for which draft genome sequences have been reported. Accordingly, little is known about functional genomics in S. haematobium, including the utility or not of RNA interference techniques that, if available, promise to guide development of new interventions for schistosomiasis haematobia.

Methods/Findings

Here we isolated and cultured developmental stages of S. haematobium, derived from experimentally infected hamsters. Targeting different developmental stages, we investigated the utility of soaking and/or square wave electroporation in order to transfect S. haematobium with nucleic acid reporters including Cy3-labeled small RNAs, messenger RNA encoding firefly luciferase, and short interfering RNAs (siRNAs). Three hours after incubation of S. haematobium eggs in 50 ng/µl Cy3-labeled siRNA, fluorescent foci were evident indicating that labeled siRNA had penetrated into miracidia developing within the egg shell. Firefly luciferase activity was detected three hours after square wave electroporation of the schistosome eggs and adult worms in 150 ng/µl of mRNA. RNA interference knockdown (silencing) of reporter luciferase activity was seen following the introduction of dsRNA specific for luciferase mRNA in eggs, schistosomules and mixed sex adults. Moreover, introduction of an endogenous gene-specific siRNA into adult schistosomes silenced transcription of tetraspanin 2 (Sh-tsp-2), the apparent orthologue of the Schistosoma mansoni gene Sm-tsp-2 which encodes the surface localized structural and signaling protein Sm-TSP-2. Together, knockdown of reporter luciferase and Sh-tsp-2 indicated the presence of an intact RNAi pathway in S. haematobium. Also, we employed laser scanning confocal microscopy to view the adult stages of S. haematobium.

Conclusions

These findings and approaches should facilitate analysis of gene function in S. haematobium, which in turn could facilitate the characterization of prospective intervention targets for this neglected tropical disease pathogen.

More people are infected with Schistosoma haematobium than other major human schistosomes yet it has been less studied because of difficulty in maintaining the life cycle in the laboratory. S. haematobium might be considered the ‘neglected schistosome’ since minimal information on the genome and proteome of S. haematobium is available, in marked contrast to the other major schistosomes. In this report we describe tools and protocols to investigate the genome and genetics of this neglected schistosome. We cultured developmental stages of S. haematobium, and investigated the utility of introducing gene probes into the parasites to silence two model genes. One of these, firefly luciferase, was a reporter gene whereas the second was a schistosome gene encoding a surface protein, termed Sh-tsp-2. We observed that both genes could be silenced – a phenomenon known as experimental RNA interference (RNAi). These findings indicated that the genome of S. haematobium will be amenable to genetic manipulation investigations designed to determine the function and importance of genes of this schistosome and to investigate for novel anti-parasite treatments.

Schistosoma mansoni enhances host susceptibility to mucosal but not intravenous challenge by R5 Clade C SHIV

Background

The high prevalence of HIV-1/AIDS in areas endemic for schistosomiasis and other helminthic infections has led to the hypothesis that parasites increase host susceptibility to immunodeficiency virus infection. We previously showed that rhesus macaques (RM) with active schistosomiasis were significantly more likely to become systemically infected after intrarectal (i.r.) exposure to an R5-tropic clade C simian-human immunodeficiency virus (SHIV-C) than were parasite-free controls. However, we could not address whether this was due to systemic or mucosal effects. If systemic immunoactivation resulted in increased susceptibility to SHIV-C acquisition, a similarly large difference in host susceptibility would be seen after intravenous (i.v.) SHIV-C challenge. Conversely, if increased host susceptibility was due to parasite-induced immunoactivation at the mucosal level, i.v. SHIV-C challenge would not result in significant differences between parasitized and parasite-free monkeys.

Methods and Findings

We enrolled two groups of RM and infected one group with Schistosoma mansoni; the other group was left parasite-free. Both groups were challenged i.v. with decreasing doses of SHIV-C. No statistically significant differences in 50% animal infectious doses (AID₅₀) or peak viremia were seen between the two groups. These data strongly contrast the earlier i.r. SHIV-C challenge (using the same virus stock) in the presence/absence of parasites, where we noted a 17-fold difference in AID₅₀ and one log higher peak viremia in parasitized monkeys (P<0.001 for both). The lack of significant differences after the i.v. challenge implies that the increased host susceptibility is predominantly due to parasite-mediated mucosal upregulation of virus replication and spread, rather than systemic effects.

Conclusions

The major impact of schistosome-induced increased host susceptibility is at the mucosal level. Given that >90% of all new HIV-1 infections worldwide are acquired through mucosal contact, parasitic infections that inflame mucosae may play an important role in the spread of HIV-1.

Parasitic infections have been postulated to increase host susceptibility to HIV-1. We previously demonstrated that rhesus monkeys with active schistosomiasis were significantly more likely to become systemically infected after intrarectal exposure to an R5-tropic clade C simian-human immunodeficiency virus then were parasite-free control animals. However, we could not address whether parasites exert their effect at the mucosal level or systemically. To address the latter possibility, we measured the virus doses needed to achieve systemic infection after intravenous exposure of parasite-free or parasite-positive monkeys using the identical virus stock. None of the viral parameters tested in these two groups of monkeys were statistically significantly different. These results suggest that schistosomiasis modulates susceptibility to immunodeficiency virus acquisition predominantly at the mucosal level. Treatment for parasitic infections in populations at higher risk for HIV-1 acquisition could represent a cost-effective approach to slow the spread of HIV-1, which is predominantly transmitted through mucosal routes.

Vaccines to combat the neglected tropical diseases

The neglected tropical diseases (NTDs) represent a group of parasitic and related infectious diseases such as amebiasis, Chagas disease, cysticercosis, echinococcosis, hookworm, leishmaniasis, and schistosomiasis. Together, these conditions are considered the most common infections in low- and middle-income countries, where they produce a level of global disability and human suffering equivalent to better known conditions such as human immunodeficiency virus/acquired immunodeficiency syndrome and malaria. Despite their global public health importance, progress on developing vaccines for NTD pathogens has lagged because of some key technical hurdles and the fact that these infections occur almost exclusively in the world's poorest people living below the World Bank poverty line. In the absence of financial incentives for new products, the multinational pharmaceutical companies have not embarked on substantive research and development programs for the neglected tropical disease vaccines. Here, we review the current status of scientific and technical progress in the development of new neglected tropical disease vaccines, highlighting the successes that have been achieved (cysticercosis and echinococcosis) and identifying the challenges and opportunities for development of new vaccines for NTDs. Also highlighted are the contributions being made by non-profit product development partnerships that are working to overcome some of the economic challenges in vaccine manufacture, clinical testing, and global access.

HelmCoP: an online resource for helminth functional genomics and drug and vaccine targets prioritization

A vast majority of the burden from neglected tropical diseases result from helminth infections (nematodes and platyhelminthes). Parasitic helminthes infect over 2 billion, exerting a high collective burden that rivals high-mortality conditions such as AIDS or malaria, and cause devastation to crops and livestock. The challenges to improve control of parasitic helminth infections are multi-fold and no single category of approaches will meet them all. New information such as helminth genomics, functional genomics and proteomics coupled with innovative bioinformatic approaches provide fundamental molecular information about these parasites, accelerating both basic research as well as development of effective diagnostics, vaccines and new drugs. To facilitate such studies we have developed an online resource, HelmCoP (Helminth Control and Prevention), built by integrating functional, structural and comparative genomic data from plant, animal and human helminthes, to enable researchers to develop strategies for drug, vaccine and pesticide prioritization, while also providing a useful comparative genomics platform. HelmCoP encompasses genomic data from several hosts, including model organisms, along with a comprehensive suite of structural and functional annotations, to assist in comparative analyses and to study host-parasite interactions. The HelmCoP interface, with a sophisticated query engine as a backbone, allows users to search for multi-factorial combinations of properties and serves readily accessible information that will assist in the identification of various genes of interest. HelmCoP is publicly available at: http://www.nematode.net/helmcop.html.

Increased vascularity in cervicovaginal mucosa with Schistosoma haematobium infection

Background

Close to 800 million people in the world are at risk of schistosomiasis, 85 per cent of whom live in Africa. Recent studies have indicated that female genital schistosomiasis might increase the risk of human immunodeficiency virus (HIV) infection. The aim of this study is to quantify and analyse the characteristics of the vasculature surrounding Schistosoma haematobium ova in the female genital mucosa.

Methodology/Principal Findings

Cervicovaginal biopsies with S. haematobium ova (n = 20) and control biopsies (n = 69) were stained with immunohistochemical blood vessel markers CD31 and von Willebrand Factor (vWF), which stain endothelial cells in capillary buds and established blood vessels respectively. Haematoxylin and eosin (HE) were applied for histopathological assessment. The tissue surrounding S. haematobium ova had a higher density of established blood vessels stained by vWF compared to healthy controls (p = 0.017). Immunostain to CD31 identified significantly more granulation tissue surrounding viable compared to calcified ova (p = 0.032), and a tendency to neovascularisation in the tissue surrounding viable ova compared to healthy cervical mucosa (p = 0.052).

Conclusions/Significance

In this study female genital mucosa with S. haematobium ova was significantly more vascularised compared to healthy cervical tissue. Viable parasite ova were associated with granulation tissue rich in sprouting blood vessels. Although the findings of blood vessel proliferation in this study may be a step to better understand the implications of S. haematobium infection, further studies are needed to explore the biological, clinical and epidemiological features of female genital schistosomiasis and its possible influence on HIV susceptibility.

Schistosomiasis is a fresh water parasite infection that affects millions of people, especially in Africa. Recent knowledge about the genital manifestations of schistosomiasis; especially its possible association with human immunodeficiency virus (HIV) infection, has led to increased focus on this neglected tropical disease. Millions of women remain undiagnosed for genital schistosomiasis, and may suffer from abnormal mucosal blood vessels, contact bleeding and lesions named sandy patches. This study analyses a unique selection of female genital biopsies containing parasite eggs. Protein detection and standard histopathological assessment are combined to quantify and study the characteristics of the mucosal blood vessels surrounding the eggs. Our results show that the genital mucosa with parasite eggs is more vascularised compared to healthy tissue, and that viable eggs tend to be surrounded by proliferating blood vessels. These findings have not yet been correlated directly to clinical manifestations. Further studies are needed in order to provide clinical advice on the risks and consequences of mucosal lesions particular to female genital schistosomiasis.

Urogenital schistosomiasis in women of reproductive age in Tanzania's Lake Victoria region

We conducted a community-based study of 457 women aged 18-50 years living in eight rural villages in northwest Tanzania. The prevalence of female urogenital schistosomiasis (FUS) was 5% overall but ranged from 0% to 11%. FUS was associated with human immunodeficiency virus (HIV) infection (odds ratio [OR] = 4.0, 95% confidence interval [CI] = 1.2-13.5) and younger age (OR = 5.5 and 95% CI = 1.2-26.3 for ages < 25 years and OR = 8.2 and 95% CI = 1.7-38.4 for ages 25-29 years compared with age > 35 years). Overall HIV prevalence was 5.9% but was 17% among women with FUS. We observed significant geographical clustering of schistosomiasis: northern villages near Lake Victoria had more Schistosoma mansoni infections (P < 0.0001), and southern villages farther from the lake had more S. haematobium (P = 0.002). Our data support the postulate that FUS may be a risk factor for HIV infection and may contribute to the extremely high rates of HIV among young women in sub-Saharan Africa.

High prevalence of persistent parasitic infections in foreign-born, HIV-infected persons in the United States

BACKGROUND

Foreign-born, HIV-infected persons are at risk for sub-clinical parasitic infections acquired in their countries of origin. The long-term consequences of co-infections can be severe, yet few data exist on parasitic infection prevalence in this population.

METHODOLOGY/PRINCIPAL FINDINGS

This cross-sectional study evaluated 128 foreign-born persons at one HIV clinic. We performed stool studies and serologic testing for strongyloidiasis, schistosomiasis, filarial infection, and Chagas disease based on the patient's country of birth. Eosinophilia and symptoms were examined as predictors of helminthic infection. Of the 128 participants, 86 (67%) were male, and the median age was 40 years; 70 were Mexican/Latin American, 40 African, and 18 from other countries or regions. Strongyloides stercoralis antibodies were detected in 33/128 (26%) individuals. Of the 52 persons from schistosomiasis-endemic countries, 15 (29%) had antibodies to schistosome antigens; 7 (47%) had antibodies to S. haematobium, 5 (33%) to S. mansoni, and 3 (20%) to both species. Stool ova and parasite studies detected helminths in 5/85 (6%) persons. None of the patients tested had evidence of Chagas disease (n = 77) or filarial infection (n = 52). Eosinophilia >400 cells/mm(3) was associated with a positive schistosome antibody test (OR 4.5, 95% CI 1.1-19.0). The only symptom significantly associated with strongyloidiasis was weight loss (OR 3.1, 95% CI 1.4-7.2).

CONCLUSIONS/SIGNIFICANCE

Given the high prevalence of certain helminths and the potential lack of suggestive symptoms and signs, selected screening for strongyloidiasis and schistosomiasis or use of empiric antiparasitic therapy may be appropriate among foreign-born, HIV-infected patients. Identifying and treating helminth infections could prevent long-term complications.

Modeling schistosomiasis and HIV/AIDS codynamics

We formulate a mathematical model for the cointeraction of schistosomiasis and HIV/AIDS in order to assess their synergistic relationship in the presence of therapeutic measures. Comprehensive mathematical techniques are used to analyze the model steady states. The disease-free equilibrium is shown to be locally asymptotically stable when the associated disease threshold parameter known as the basic reproduction number for the model is less than unity. Centre manifold theory is used to show that the schistosomiasis-only and HIV/AIDS-only endemic equilibria are locally asymptotically stable when the associated reproduction numbers are greater than unity. The impact of schistosomiasis and its treatment on the dynamics of HIV/AIDS is also investigated. To illustrate the analytical results, numerical simulations using a set of reasonable parameter values are provided, and the results suggest that schistosomiasis treatment will always have a positive impact on the control of HIV/AIDS.