Schistosoma haematobium infection and CD4+ T-cell levels: a cross-sectional study of young South African women

Predictors for participation in mass-treatment and female genital schistosomiasis re-investigation, and the effect of praziquantel treatment in South African adolescents

OBJECTIVE

Female Genital Schistosomiasis (FGS) causes intravaginal lesions and symptoms that could be mistaken for sexually transmitted diseases or cancer. In adults, FGS lesions [grainy sandy patches (GSP), homogenous yellow patches (HYP), abnormal blood vessels and rubbery papules] are refractory to treatment. The effect of treatment has never been explored in young women; it is unclear if gynaecological investigation will be possible in this young age group (16-23 years). We explored the predictors for accepting anti-schistosomal treatment and/or gynaecological reinvestigation in young women, and the effects of anti-schistosomal mass-treatment (praziquantel) on the clinical manifestations of FGS at an adolescent age.

METHOD

The study was conducted between 2011 and 2013 in randomly selected, rural, high schools in Ilembe, uThungulu and Ugu Districts, KwaZulu-Natal Province, East Coast of South Africa. At baseline, gynaecological investigations were conducted in female learners in grades 8 to 12, aged 16-23 years (n = 2293). Mass-treatment was offered in the low-transmission season between May and August (a few in September, n = 48), in accordance with WHO recommendations. Reinvestigation was offered after a median of 9 months (range 5-14 months). Univariate, multivariable and logistic regression analysis were used to measure the association between variables.

RESULTS

Prevalence: Of the 2293 learners who came for baseline gynaecological investigations, 1045 (46%) had FGS lesions and/or schistosomiasis, 209/1045 (20%) had GSP; 208/1045 (20%) HYP; 772/1045 (74%) had abnormal blood vessels; and 404/1045 (39%) were urine positive. Overall participation rate for mass treatment and gynaecological investigation: Only 26% (587/2293) learners participated in the mass treatment and 17% (401/2293) participated in the follow up gynaecological reinvestigations. Loss to follow-up among those with FGS: More than 70% of learners with FGS lesions at baseline were lost to follow-up for gynaecological investigations: 156/209 (75%) GSP; 154/208 (74%) HYP; 539/722 (75%) abnormal blood vessels; 238/404 (59%) urine positive. The grade 12 pupil had left school and did not participate in the reinvestigations (n = 375; 16%). Follow-up findings: Amongst those with lesions who came for both treatment and reinvestigation, 12/19 still had GSP, 8/28 had HYP, and 54/90 had abnormal blood vessels. Only 3/55 remained positive for S. haematobium ova. Factors influencing treatment and follow-up gynaecological investigation: HIV, current water contact, water contact as a toddler and urinary schistosomiasis influenced participation in mass treatment. Grainy sandy patches, abnormal blood vessels, HYP, previous pregnancy, current water contact, water contact as a toddler and father present in the family were strongly associated with coming back for follow-up gynaecological investigation. Challenges in sample size for follow-up analysis of the effect of treatment: The low mass treatment uptake and loss to follow up among those who had baseline FGS reduced the chances of a larger sample size at follow up investigation. However, multivariable analysis showed that treatment had effect on the abnormal blood vessels (adjusted odds ratio = 2.1, 95% CI 1.1-3.9 and p = 0.018).

CONCLUSION

Compliance to treatment and gynaecological reinvestigation was very low. There is need to embark on large scale awareness and advocacy in schools and communities before implementing mass-treatment and investigation studies. Despite challenges in sample size and significant loss to follow-up, limiting the ability to fully understand the treatment's effect, multivariable analysis demonstrated a significant treatment effect on abnormal blood vessels.

Effects of schistosomes on host anti-viral immune response and the acquisition, virulence, and prevention of viral infections: A systematic review

Although a growing number of studies suggest interactions between Schistosoma parasites and viral infections, the effects of schistosome infections on the host response to viruses have not been evaluated comprehensively. In this systematic review, we investigated how schistosomes impact incidence, virulence, and prevention of viral infections in humans and animals. We also evaluated immune effects of schistosomes in those coinfected with viruses. We screened 4,730 studies and included 103. Schistosomes may increase susceptibility to some viruses, including HIV and Kaposi’s sarcoma-associated herpesvirus, and virulence of hepatitis B and C viruses. In contrast, schistosome infection may be protective in chronic HIV, Human T-cell Lymphotropic Virus-Type 1, and respiratory viruses, though further research is needed. Schistosome infections were consistently reported to impair immune responses to hepatitis B and possibly measles vaccines. Understanding the interplay between schistosomes and viruses has ramifications for anti-viral vaccination strategies and global control of viral infections.

Many studies have described the effects of parasitic Schistosoma worm infections on the way that humans and animals respond to a variety of viral infections. Our goal was to evaluate, in a systematic manner, how having a schistosome parasitic infection affects a host’s susceptibility to viral infections, the clinical disease course of viral infections, and prevention of viral infections by vaccines. We also assessed the effects of schistosome infection on the host immune response to viruses. We screened 4,730 studies for potential relevance and included 103 of them in this review. Overall, our analysis showed that schistosome infection impairs the host response to many viruses. This includes increasing host susceptibility to HIV and possibly Kaposi’s sarcoma-associated herpesvirus, worsening the severity of clinical disease in hepatitis B and C infections, and decreasing immune responses to vaccines for hepatitis B and possibly measles. The studies that we analyzed also suggested that schistosome infection may protect the host against poor clinical outcomes from some viral infections including Human T-cell Lymphotropic Virus-Type 1, respiratory viruses, and chronic HIV. We discuss how these findings might be interpreted, and the additional research needed, in order to improve anti-viral vaccination strategies and control of viral infections globally.

A systematic review of handheld tools in lieu of colposcopy for cervical neoplasia and female genital schistosomiasis

Background

Visualization of the lesions in the lower genital tract is the mainstay for diagnosis of the four lesions found in female genital schistosomiasis (FGS), but colposcopes are generally not available in low‐resource settings.

Objective

We sought to review handheld devices that could potentially be used for FGS diagnosis.

Search strategy

We searched Medline and Embase 2015–2019 for handheld devices used in cervical cancer screening and FGS diagnosis.

Selection criteria

We excluded studies that did not compare the device to standard‐of‐care colposcopes or histopathology.

Main results and conclusion

In 11 studies, four handheld colposcopes, two smartphones, and one compact digital camera were evaluated. Two handheld colposcopes were found to be potentially adequate for FGS diagnosis, namely Gynocular and Mobile ODT. The smartphones and digital camera did not have sufficient magnification to diagnose grainy sandy patches, one of the FGS lesion types. Customized software should be made to support the diagnosis of both FGS and cervical neoplasia. Real‐time postgraduate training and quality control should be considered in future studies of handheld colposcopes. For patients from schistosomiasis endemic areas, we recommend that handheld devices are used for FGS. Studies are needed to determine which of the two devices is most adequate for FGS diagnosis in schistosomiasis endemic areas.

Handheld colposcopy for schistosomiasis endemic areas should be adequate for both cervical cancer and genital schistosomiasis diagnoses.

Association of schistosomiasis and HIV infections: A systematic review and meta-analysis

Background:

Female genital schistosomiasis (FGS) affects up to 56 million women in sub-Saharan Africa and may increase risk of HIV infection.

Methods:

To assess the association of schistosomiasis with HIV infection, peer-reviewed literature published until 31 December 2018 was examined and a pooled estimate for the odds ratio was generated using Bayesian random effects models.

Results:

Of the 364 abstracts that were identified, 26 were included in the summary. Eight reported odds ratios of the association between schistosomiasis and HIV; one reported a transmission hazard ratio of 1.8 (95% CI, 1.2–2.6) among women and 1.4 (95% CI, 1.0–1.9) among men; 11 described the prevalence of schistosomiasis among HIV-positive people (range, 1.5–36.6%); and six reported the prevalence of HIV among people with schistosomiasis (range, 5.8–57.3%). Six studies were selected for quantitative analysis. The pooled estimate for the odds ratio of HIV among people with schistosomiasis was 2.3 (95% CI, 1.2–4.3).

Conclusions:

A significant association of schistosomiasis with HIV was found. However, a specific summary estimate for FGS could not be generated. A research agenda was provided to determine the effect of FGS on HIV infection. The WHO’s policy on mass drug administration for schistosomiasis may prevent HIV.

Schistosoma haematobium infection and environmental factors in Southwestern Tanzania: A cross-sectional, population-based study

Schistosomiasis is a leading cause of morbidity in Africa. Understanding the disease ecology and environmental factors that influence its distribution is important to guide control efforts. Geographic information systems have increasingly been used in the field of schistosomiasis environmental epidemiology. This study reports prevalences of Schistosoma haematobium infection and uses remotely sensed and questionnaire data from over 17000 participants to identify environmental and socio-demographic factors that are associated with this parasitic infection. Data regarding socio-demographic status and S. haematobium infection were obtained between May 2006 and May 2007 from 17280 participants (53% females, median age = 17 years) in the Mbeya Region, Tanzania. Combined with remotely sensed environmental data (vegetation cover, altitude, rainfall etc.) this data was analyzed to identify environmental and socio-demographic factors associated with S. haematobium infection, using mixed effects logistic regression and geostatistical modelling. The overall prevalence of S. haematobium infection was 5.3% (95% confidence interval (CI): 5.0-5.6%). Multivariable analysis revealed increased odds of infection for school-aged children (5-15 years, odds ratio (OR) = 7.8, CI: 5.9-10.4) and the age groups 15-25 and 25-35 years (15-25 years: OR = 5.8, CI: 4.3-8.0, 25-35 years: OR = 1.6, CI: 1.1-2.4) compared to persons above 35 years of age, for increasing distance to water courses (OR = 1.4, CI: 1.2-1.6 per km) and for proximity to Lake Nyasa (<1 km, OR = 4.5, CI: 1.8-11.4; 1-2 km, OR = 3.5, CI: 1.7-7.5; 2-4 km; OR = 3.3, CI: 1.7-6.6), when compared to distances >4 km. Odds of infection decreased with higher altitude (OR = 0.7, CI: 0.6-0.8 per 100 m increase) and with increasing enhanced vegetation index EVI (OR = 0.2, CI: 0.1-0.4 per 0.1 units). When additionally adjusting for spatial correlation population density became a significant predictor of schistosomiasis infection (OR = 1.3, CI: 1.1-1.5 per 1000 persons/km2) and altitude turned non-significant. We found highly focal geographical patterns of S. haematobium infection in Mbeya Region in Southwestern Tanzania. Despite low overall prevalence our spatially heterogeneous results show that some of the study sites suffer from a considerable burden of S. haematobium infection, which is related to various socio-demographic and environmental factors. Our results could help to design more effective control strategies in the future, especially targeting school-aged children living in low altitude sites and/or crowded areas as the persons at highest need for preventive chemotherapy.

A systematic review and meta-analysis to assess the association between urogenital schistosomiasis and HIV/AIDS infection

Background

Urogenital schistosomiasis and HIV/AIDS infections are widespread in sub-Saharan Africa (SSA) leading to substantial morbidity and mortality. The co-occurrence of both diseases has led to the possible hypothesis that urogenital schistosomiasis leads to increased risk of acquiring HIV infection. However, the available evidence concerning this association is inconsistent. The aim of this study was to systematically review and quantitatively synthesize studies that investigated the association between urogenital schistosomiasis and HIV/AIDS infection.

Methods

A systematic review basing on PRISMA guidelines was conducted. It is registered with PROSPERO, number CRD42018116648. We searched four databases, MEDLINE, EMBASE, Global Health and Global Index Medicus for studies investigating the association between urogenital schistosomiasis and HIV infection. Only studies published in English were considered. Results of the association were summarised by gender. A meta-analysis was performed for studies on females using random-effects model and a pooled OR with 95% confidence interval was reported.

Results

Of the 993 studies screened, only eight observational studies met the inclusion criteria. Across all studies, the reported unadjusted OR ranged from 0.78 to 3.76. The pooled estimate of unadjusted OR among females was 1.31 (95% CI: 0.87–1.99). Only four of the eight studies reported an adjusted OR. A separate meta-analysis done in the three studies among females that reported an adjusted OR showed that the pooled estimate was 1.85 (95% CI: 1.17–2.92). There were insufficient data to pool results for association between urogenital schistosomiasis and HIV infection in the males.

Conclusion

Our investigation supports the hypothesis of an association between urogenital schistosomiasis with HIV/AIDS infection in females. Due to insufficient evidence, no conclusion could be drawn in males with urogenital schistosomiasis. Large-scale prospective studies are needed in future.

Urogenital schistosomiasis, caused by parasitic trematode Schistosoma haematobium is a significant source of morbidity in sub Saharan Africa. HIV infection caused by a retrovirus is of two subtypes HIV 1 and HIV 2, with subtype HIV 1 being found worldwide and more aggressive, leading to HIV/AIDS. Research on both of these diseases in the same settings, has shown that these diseases cross paths. This has led to the suggestion that there could be a possible association between the two. Here we describe a systematic review that was carried out to determine if there is an association between UGS and HIV/AIDS infections. We searched all published articles available in MEDLINE, EMBASE, Global Health (CABI), and Global Index Medicus before 28^th January 2020. We found eight observational studies eligible to be included in the systematic review and no intervention study. Six of these studies were included in the meta-analysis. A summarized meta-analysis of the study findings with adjusted OR showed that there was a likely association between urogenital schistosomiasis and HIV/AIDS infections in females. However, due to limited papers in males, no conclusion could be drawn.

Female Genital Schistosomiasis and HIV: Research Urgently Needed to Improve Understanding of the Health Impacts of This Important Coinfection

Evidence suggests that there are important interactions between HIV and female genital schistosomiasis (FGS) that may have significant effects on individual and population health. However, the exact way they interact and the health impacts of the interactions are not well understood. In this article, we discuss what is known about the interactions between FGS and HIV, and the potential impact of the interactions. This includes the likelihood that FGS is an important health problem for HIV-positive women in Schistosoma-endemic areas potentially associated with an increased risk of mortality, cancer, and infertility. In addition, it may be significantly impacting the HIV epidemic in sub-Saharan Africa by making young women more susceptible to HIV. We call for immediate action and argue that research is urgently required to address these knowledge gaps and propose a research agenda to achieve this.

Impact of Endemic Infections on HIV Susceptibility in Sub-Saharan Africa

Human immunodeficiency virus (HIV) remains a leading cause of global morbidity with the highest burden in Sub-Saharan Africa (SSA). For reasons that are incompletely understood, the likelihood of HIV transmission is several fold higher in SSA than in higher income countries, and most of these infections are acquired by young women. Residents of SSA are also exposed to a variety of endemic infections, such as malaria and various helminthiases that could influence mucosal and systemic immunology. Since these immune parameters are important determinants of HIV acquisition and progression, this review explores the possible effects of endemic infections on HIV susceptibility and summarizes current knowledge of the epidemiology and underlying immunological mechanisms by which endemic infections could impact HIV acquisition. A better understanding of the interaction between endemic infections and HIV may enhance HIV prevention programs in SSA.

Schistosoma "Eggs-Iting" the Host: Granuloma Formation and Egg Excretion

Schistosomiasis is a major cause of morbidity in humans invoked by chronic infection with parasitic trematodes of the genus Schistosoma. Schistosomes have a complex life-cycle involving infections of an aquatic snail intermediate host and a definitive mammalian host. In humans, adult male and female worms lie within the vasculature. Here, they propagate and eggs are laid. These eggs must then be released from the host to continue the life cycle. Schistosoma mansoni and Schistosoma japonicum reside in the mesenteric circulation of the intestines with egg excreted in the feces. In contrast, S. haematobium are present in the venus plexus of the bladder, expelling eggs in the urine. In an impressive case of exploitation of the host immune system, this process of Schistosome “eggs-iting” the host is immune dependent. In this article, we review the formation of the egg granuloma and explore how S. mansoni eggs laid in vasculature must usurp immunity to induce regulated inflammation, to facilitate extravasation through the intestinal wall and to be expelled in the feces. We highlight the roles of immune cell populations, stromal factors, and egg secretions in the process of egg excretion to provide a comprehensive overview of the current state of knowledge regarding a vastly unexplored mechanism.

HIV-1 Viral Loads Are Not Elevated in Individuals Co-infected With Schistosoma spp. After Adjustment for Duration of HIV-1 Infection

Studies of the role of Schistosoma co-infections on plasma HIV-1 RNA (HIV-1 viral load) have yielded incongruent results. The role of duration of HIV-1 infection on the link between Schistosoma and HIV-1 viral load has not been previously investigated. We aimed to assess the impact of HIV-1/Schistosoma co-infections on viral load in Antiretroviral Treatment (ART)-naïve HIV-1 infected people taking into account the duration of HIV-1 infection. We describe 79 HIV-infected outpatients greater than 18 years of age who had never used ART in Mwanza, Tanzania. Schistosomiasis testing was done by urine and stool microscopy and by serum Schistosoma circulating anodic antigen (CAA) testing. Schistosoma positivity was defined as having either test positive. We conducted univariable and multivariable linear regressions to assess the relationship between Schistosoma infection and the log₁₀ of viral load. Duration of HIV infection was calculated using the first measured CD4⁺ T-cell (CD4) count as a function of normal CD4 count decay per calendar year in drug naïve individuals. An active Schistosoma infection was demonstrated in 46.8% of the patients. The median log₁₀ viral load was 4.5[3.4–4.9] log₁₀ copies/mL in Schistosoma uninfected patients and 4.3[3.7–4.6] log₁₀ copies/mL in Schistosoma infected patients. Schistosoma co-infection was negatively associated with the log₁₀ of viral load after adjustment for Schistosoma intensity as measured by CAA, CD4 counts at time of testing, and duration of HIV-1 infection (β = −0.7[−1.3;−0.1], p = 0.022). Schistosoma co-infection was not associated with viral load in univariable analysis. There was also no interaction between Schistosoma positivity and duration of HIV-1 infection. Our study is the first, to our knowledge, to report adjustment for duration of HIV-1 infection when analyzing the relationship between HIV-1 viral load and Schistosoma spp. We found that time infected with HIV-1 has a major effect on the relationship between HIV-1 viral load and Schistosoma infection and may be a critical explanatory factor in the disparate findings of studies on HIV-1 viral load and schistosomiasis. The log₁₀ viral load difference found indicates that Schistosoma co-infection does not make HIV progression worse, and could possibly lead to slower HIV disease progression.

Impact of schistosome infection on long-term HIV/AIDS outcomes

Background

Africa bears the burden of approximately 70% of global HIV infections and 90% of global schistosome infections. We sought to investigate the impact of schistosome infection at the time of HIV-1 seroconversion on the speed of HIV-1 disease progression, as measured by the outcome CD4+ T-cell (CD4) counts <350 cells/μL and/or death. We hypothesized that people who had been infected with Schistosoma spp. at the time they acquired HIV-1 infection would have impaired antiviral immune response, thus leading them to progress twice as fast to a CD4 count less than 350 cells/μL or death than would people who had been free of schistosomes at time of HIV-1 seroconversion.

Methods and principal findings

We conducted a longitudinal study in Tanzania from 2006 to 2017 using stored blood spot samples, demographic surveillance and sero-survey data from the community, and a review of clinical charts. A competing risk analysis was performed to look at the difference in time to reaching CD4 counts < 350 cells/μL and/or death in HIV-1-infected people who were infected versus not infected with Schistosoma spp. at time of HIV-1 seroconversion. We found an 82% reduction in risk of reaching the outcome in seroconverters who had been infected with Schistosoma (subHazard Ratio = 0.18[0.068,0.50], p = 0.001) after adjusting for age, occupation, clinic attendance and time-dependent covariates.

Conclusions

Our study demonstrates that people with schistosome infection at the time of HIV-seroconversion develop adverse HIV outcomes more slowly than those without. The findings are contrary to our original hypothesis. Our current longitudinal findings suggest complex interactions between HIV-1 and schistosome co-infections that may be modulated over time. We urge new immunological studies to investigate the long-term impact of schistosome infection on HIV-1 viral load and CD4 counts as well as related immunologic pathways.

Several studies had shown that people infected with schistosome parasites were at risk of getting HIV and that they may have higher HIV viral concentrations in their blood as well. The authors explored the impact of the parasite on HIV disease after infection, expecting that people co-infected with the parasite at time of HIV-infection would develop worse HIV outcomes than people who did not have the parasite. HIV seroconverters were identified among a large cohort tested regularly for HIV in northwest Tanzania and were followed-up in clinics to determine their CD4 + T-cells counts and mortality. The seroconverters’ stored blood samples were tested for infection with the parasite and outcomes were compared between seroconverters who were and were not infected with the parasites at the time that they became HIV-infected. The authors surprisingly found that people with the parasite experienced fewer negative outcomes of HIV than people who did not have the parasite. To the investigators’ knowledge, this is the first longitudinal study to find this result. Long-term immunological changes may explain this protective effect and more studies are recommended to explore this research question.

Decreased Sensitivity of Schistosoma sp. Egg Microscopy in Women and HIV-Infected Individuals

It has been postulated that impaired host immunity due to HIV infection reduces parasite egg excretion. Schistosoma/HIV interactions have also been shown to differ by sex. We hypothesized that egg excretion would vary based on both HIV status and sex. We examined data from more than 1,700 participants in eight studies conducted in northwest Tanzania between 2010 and 2016. Schistosoma infection was defined by circulating anodic antigen (CAA) serum levels ≥ 30 pg/mL and/or egg positivity in either stool by Kato Katz method or urine by filtration. We used multivariable analyses to determine the impact of confounding factors such as sex, age, previous praziquantel treatment, and worm burden as measured by serum CAA level, on the relationship between egg excretion and HIV status. HIV-infected individuals were significantly less likely to excrete schistosome eggs than HIV-uninfected individuals, even after controlling for worm burden and sex (OR = 0.6 [0.4, 0.9], P = 0.005). Furthermore, after controlling for worm burden and HIV status, women had lower odds of egg excretion than men (OR = 0.4 [0.3, 0.5], P < 0.001). Sensitivity of egg microscopy was lower in HIV-infected women than HIV-uninfected men (41% versus 61%, P < 0.001), whereas sensitivity in women remained low in both groups (33% versus 37%, P = 0.664). Our study is the first to report that women with Schistosoma infection excrete fewer eggs than men for a given worm burden, regardless of HIV the status. These findings suggest that guidelines for use of microscopy to diagnose Schistosoma infections in HIV-infected individuals and in women merit reconsideration.

Female genital schistosomiasis (FGS): from case reports to a call for concerted action against this neglected gynaecological disease

In recent years, control of neglected tropical diseases has been increasingly gaining momentum and interventions against schistosomiasis are being progressively scaled-up through expansion of donated praziquantel and preventive chemotherapy campaigns. However, the public health importance of female genital schistosomiasis is not fully recognised nor its control is adequately addressed. Taking a clinical and anatomopathological perspective, we evaluated the available literature to highlight the importance of female genital schistosomiasis and its connections with two sexually transmitted infections of global importance, Human Immunodeficiency Virus (HIV) and Human Papilloma Virus. Outside the long list of clinical descriptive reports beginning in 1899, there is presently a shocking gap in epidemiological assessment and a significant underestimation of the burden of FGS remains. The scarcity of integrated approaches to address female genital schistosomiasis calls for more concerted action in its detection, treatment and prevention alongside other concomitant women's health issues, otherwise female genital schistosomiasis will remain a neglected gynaecological disease.

Schistosoma mansoni Infection in Ugandan Men Is Associated with Increased Abundance and Function of HIV Target Cells in Blood, but Not the Foreskin: A Cross-sectional Study

Background

Schistosoma mansoni infection has been associated with an increased HIV prevalence in humans and SHIV incidence in primate models. We hypothesized that immune activation from this gastrointestinal mucosa infection would increase highly HIV-susceptible CD4 T cell subsets in the blood and the foreskin through common mucosal homing.

Methodology/Principal Findings

Foreskin tissue and blood were obtained from 34 HIV- and malaria-uninfected Ugandan men who volunteered for elective circumcision, 12 of whom were definitively positive for S. mansoni eggs in stool and 12 definitively negative for both S. mansoni eggs and worm antigen. Tissue and blood T cell subsets were characterized by flow cytometry and immunohistochemistry (IHC). Th17 and Th1 cells from both the blood and foreskin expressed higher levels of CCR5 and were more activated than other CD4 T cell subsets. S. mansoni-infected men had a higher frequency of systemic Th1 cells (22.9 vs. 16.5% of blood CD4 T cells, p<0.05), Th17 cells (2.3 vs. 1.5%, p<0.05), and Th22 cells (0.5 vs. 0.3%, p<0.01) than uninfected men. Additionally, Th17 cells in the blood of S. mansoni-infected men demonstrated enhanced function (28.1 vs. 16.3% producing multiple cytokines, p = 0.046). However, these immune alterations were not observed in foreskin tissue.

Conclusions/Significance

S. mansoni infection was associated with an increased frequency of highly HIV-susceptible Th1, Th17 and Th22 cell subsets in the blood, but these T cell immune differences did not extend to the foreskin. S. mansoni induced changes in T cell immunology mediated through the common mucosal immune system are not likely to increase HIV susceptibility in the foreskin.

Fishing communities in East Africa have a very high prevalence of HIV, and also high rates of other endemic infections such as malaria and the fluke Schistosoma mansoni. Genital infections are known to increase HIV susceptibility through the recruitment and activation of mucosal CD4 T cells to the site of HIV sexual exposure. These activated CD4 T cells are necessary for an effective host immune response but are also preferentially infected by HIV. We hypothesized that S. mansoni infection in the gut mucosa might increase recruitment and activation of HIV target cells at other mucosal sites, and thereby contribute to high HIV rates in fishing communities. We enrolled men from a fishing community in Uganda and examined the frequency of highly HIV-susceptible cell types in their blood and foreskin tissue (a main site of HIV acquisition in heterosexual men). We found that men with S. mansoni infection had a greater frequency of HIV target cells in their blood, but not their foreskin tissue, perhaps because foreskin cells did not express mucosal homing markers. It is possible that HIV target cells observed in the blood of S. mansoni-infected individuals may traffic to other mucosae, such as the vagina or gut, and so the possibility that S. mansoni infection increases risk at these sites should be explored.

An interesting finding in the uterine cervix: Schistosoma hematobium calcified eggs

Schistosoma hematobium infection is an endemic parasitic disease in Africa, which is frequently associated with urinary schistosomiasis. The parasite infection causes epithelial changes and disruption, facilitating the infection by the human papilloma virus and human immunodeficiency virus (HIV).

The authors report the case of a 44-year-old African HIV-positive woman who presented an abnormal routine Pap smear. Colposcopy examination revealed dense acetowhite micropapillary epithelium covering the ectocervix, iodine-negative, an erosion area in endocervical canal, and atypical vessels. Histologic examination of the surgical specimens showed numerous calcified schistosome eggs (probably S. hematobium) and a high-grade cervical intraepithelial neoplasia.

The relation between S. hematobium infection and bladder cancer is well known; however, this relationship with cervical cancer remains controversial. The symptoms of schistosomiasis of the female genital tract are rather non-specific, and are often misdiagnosed with other pelvic diseases. The familiarity of health professionals with schistosomiasis of the female genital tract is less than expected, even in endemic regions. Therefore, great awareness of this differential diagnosis in routine gynecological practice is of paramount importance.