The WHO atlas for female-genital schistosomiasis: Co-design of a practicable diagnostic guide, digital support and training

Up to 56 million young and adult women of African origin suffer from Female Genital Schistosomiasis (FGS). The transmission of schistosomiasis happens through contact with schistosomiasis infested fresh water in rivers and lakes. The transmission vector is the snail that releases immature worms capable of penetrating the human skin. The worm then matures and mates in the blood vessels and deposits its eggs in tissues, causing urogenital disease. There is currently no gold standard for FGS diagnosis. Reliable diagnostics are challenging due to the lack of appropriate instruments and clinical skills. The World Health Organisation (WHO) recommends "screen-and-treat" cervical cancer management, by means of visual inspection of characteristic lesions on the cervix and point-of-care treatment as per the findings. FGS may be mistaken for cervical cancer or sexually transmitted diseases. Misdiagnosis may lead to the wrong treatment, increased risk of exposure to other infectious diseases (human immunodeficiency virus and human papilloma virus), infertility and stigmatisation. The necessary clinical knowledge is only available to a few experts in the world. For an appropriate diagnosis, this knowledge needs to be transferred to health professionals who have minimal or non-existing laboratory support. Co-design workshops were held with stakeholders (WHO representative, national health authority, FGS experts and researchers, gynaecologists, nurses, medical doctors, public health experts, technical experts, and members of the public) to make prototypes for the WHO Pocket Atlas for FGS, a mobile diagnostic support tool and an e-learning tool for health professionals. The dissemination targeted health facilities, including remote areas across the 51 anglophone, francophone and lusophone African countries. Outcomes were endorsed by the WHO and comprise a practical diagnostic guide for FGS in low-resource environments.

The Association Between Female Genital Schistosomiasis and Other Infections of the Lower Genital Tract in Adolescent Girls and Young Women: A Cross-Sectional Study in South Africa

OBJECTIVES/PURPOSES OF THE STUDY

This study aimed to explore the relationship between female genital schistosomiasis (FGS), sexually transmitted infections, bacterial vaginosis, and yeast among young women living in Schistosoma haematobium-endemic areas.

METHODS

In a cross-sectional study of young women, sexually active, aged 16 to 22 years in rural KwaZulu-Natal, South Africa, in 32 randomly selected rural schools in schistosomiasis-endemic areas, the authors performed gynecological and laboratory investigations, diagnosed FGS and other infections, and did face-to-face interviews.

RESULTS

Female genital schistosomiasis was the second most prevalent current genital infection (23%), significantly more common in those who had urinary schistosomiasis (35%), compared with those without (19%, p < .001). In the FGS-positive group, 35% had human papillomavirus compared with 24% in the FGS-negative group (p = .010). In the FGS-positive group, 37% were seropositive for herpes simplex virus infection, compared with 30% in the FGS-negative group (p = .079). There were significantly fewer chlamydia infections among women with FGS (20%, p = .018) compared with those who did not have FGS (28%).

CONCLUSIONS

Female genital schistosomiasis was the second most common genital infection after herpes simplex virus. Human papillomavirus infection was significantly associated with FGS, but Chlamydia was negatively associated with FGS. Women with FGS may have had more frequent contact with the health system for genital discharge. The results show the importance of the inclusion of FGS in the national management protocols for genital infections in areas endemic for S. haematobium and highlight a more comprehensive approach to diagnosis and genital disease management.

Knowledge and perceptions about schistosomiasis among primary school children and teachers in rural KwaZulu-Natal

Background

Schistosomiasis is a disease caused by parasitic trematode worms of the genus Schistosoma. In 2014, over 258 million people worldwide required treatment for the disease. Schistosomiasis is known to be prevalent in the northern region of KwaZulu-Natal province of South Africa, especially among school-going children but less is known about their knowledge of the disease and their attitude towards being treated for the disease at school.

Methods

The study was a descriptive and analytical cross-sectional survey conducted through self-administered questionnaires among grades 5 and 7 learners from 10 randomly selected rural primary schools in iLembe and uThungulu, KwaZulu-Natal. Teachers from the same schools participated during the same period.

Results

A total of 730 learners and 78 teachers took part in the study. Among the learners, 73.2% (95% confidence interval [CI]: 69.7% – 76.4%) correctly identified freshwater contact as a risk for schistosomiasis, but only 42.7% (95% CI: 38.8% – 46.8%) knew how to prevent it. Among the teachers, 96.8% (95% CI: 87.8% – 99.4%) knew the risk and 69.0% (95% CI: 55.3%– 80.1%) knew the prevention of schistosomiasis. Almost 70% (95% CI: 65.9% – 72.8%) of the learners and 67.6% (95% CI: 42.1% – 65.6%) of the teachers reported their willingness to receive treatment with praziquantel at school.

Conclusion

This study showed that basic knowledge about the risk of schistosomiasis among the participants was high, but the cause and prevention of the disease were less well understood. There is need to include schistosomiasis in health education both at school and through community awareness programmes.

Self-sampling for human papillomavirus testing among rural young women of KwaZulu-Natal, South Africa

BACKGROUND

Cervical cancer is a major problem in women and it is important to find a suitable and acceptable screening method, especially among young in low-resource areas for future human papillomavirus (HPV) vaccine follow-up investigations. The study sought to test the acceptability of self-sampling as well as the suitability of the specimen collecting devices.

METHODS

Ninety-eight young women from rural KwaZulu-Natal were enrolled between March and July 2014. Collected genital specimens were transferred to colour indicator cards for HPV detection. Participants answered a questionnaire where they described their experiences with self-sampling. Samples were tested for high-risk HPV using GP5/6+ PCR.

RESULTS

Of the enrolled participants, 91 answered questionnaires and indicated that self-sampling was preferred by 51/91 (56%) women while 40/91 (44%) indicated preference for sampling by a doctor (p = 0.023). The majority, 64% were comfortable using a swab, 22% preferred a brush while 11% were comfortable with both devices. Of the 98 self-sampled specimens 61 were negative for HPV in both specimens while 37 were HPV-positive in either brush or swab. Of the 37, 26 (70%) were HPV-positive in both brush and swab (kappa = 0.743) and 11 (30%) were discordant.

CONCLUSIONS

Self-sampling was acceptable to the majority of participants in this rural area. The Dacron swab was the preferred device, and can be used in combination with colour indicator cards for comfortable self-sampling, easy storage and transport of specimens plus detection.

The colposcopic atlas of schistosomiasis in the lower female genital tract based on studies in Malawi, Zimbabwe, Madagascar and South Africa

BACKGROUND

Schistosoma (S.) haematobium is a neglected tropical disease which may affect any part of the genital tract in women. Female genital schistosomiasis (FGS) may cause abnormal vaginal discharge, contact bleeding, genital tumours, ectopic pregnancies and increased susceptibility to HIV. Symptoms may mimic those typical of sexually transmitted infections (STIs) and women with genital schistosomiasis may be incorrectly diagnosed. An expert consensus meeting suggested that the following findings by visual inspection should serve as proxy indicators for the diagnosis of schistosomiasis of the lower genital tract in women from S. haematobium endemic areas: sandy patches appearing as (1) single or clustered grains or (2) sandy patches appearing as homogenous, yellow areas, or (3) rubbery papules. In this atlas we aim to provide an overview of the genital mucosal manifestations of schistosomiasis in women.

METHODOLOGY/PRINCIPAL FINDINGS

Photocolposcopic images were captured from women, between 1994 and 2012 in four different study sites endemic for S. haematobium in Malawi, Zimbabwe, South Africa and Madagascar. Images and specimens were sampled from sexually active women between 15 and 49 years of age. Colposcopic images of other diseases are included for differential diagnostic purposes.

SIGNIFICANCE

This is the first atlas to present the clinical manifestations of schistosomiasis in the lower female genital tract. It will be freely available for online use, downloadable as a presentation and for print. It could be used for training purposes, further research, and in clinical practice.

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.

Schistosome immunology: more questions than answers

The past 30 years have seen research on the immunology of schistosomiasis move to encompass studies of responses in naturally exposed human populations, in addition to the studies in animal model systems. While animal systems still retain an important place in research on the immunology of schistosomiasis, recent debate has centred on aspects of human immunological responses that may or may not be associated with resistance or susceptibility to infection. In this article, Paul Hagan, Patricia Ndhlovu and David Dunne take stock of the present state of knowledge and offer their views on prospects for the future.

Similar cellular responses after treatment with either praziquantel or oxamniquine in Schistosoma mansoni infection

The effect of treatment with either oxamniquine or praziquantel on S.mansoni specific IFN-gamma, IL-4, IL-5 and IL-10 was compared on PBMC which were collected pretreatment, 6 and 18 weeks post treatment. Using sandwich ELISA on the supernatants harvested from the PBMC stimulation by crude S. mansoni SEA and SWAP antigens after 5 days the levels of PBMC proliferation and cytokine production were similar according to treatment with either praziquantel or oxamniquine. Before treatment, infected groups showed low ratios, of IL-4:IFN-gamma, IL-5:IFNgamma and IL-10:IFN-gamma, indicating that IFN-gamma was high in the infected individuals. The general increase in immuno-modulation was observed post-treatment with elevated immune reactivity and cytokine production in both treatment groups. Treatment induced significant increases in levels of IL-4 (p < 0.05), IL-5 (p < 0.0001) and IL-10 (p < 0.05) cytokines 6 and 18 weeks after treatment. There were no significant differences in the increase in IL-4, IL-5 and IL-10 between children treated with praziquantel or oxamniquine. Pre-treatment IFN-gamma and IL-5 levels were positively correlated with infection (p < 0.001), while post treatment IL-4 cytokine levels were negatively correlated with baseline infection status (p < 0.001). The results suggest that treatment-induced immune responses are similar for both common anti-schistosome drugs praziquantel or oxamniquine having similar and immunizing effect.

Schistosomiasis PCR in vaginal lavage as an indicator of genital Schistosoma haematobium infection in rural Zimbabwean women

Schistosoma real-time polymerase chain reaction (PCR) is sensitive and specific in urine and stool. We sought to explore the relationship between genital schistosomiasis and the Schistosoma PCR in women. PCR was run on 83 vaginal lavage samples from a rural Zimbabwean population. Women underwent clinical and colposcopic investigations, analyses for sexually transmitted infections, and genital schistosomiasis. Thirty samples were positive for Schistosoma PCR: 12 were strong and 18 were weak positive. Sensitivity (67%) and specificity (83%) were best in women below the age of 25 years. A positive schistosome PCR result was associated with S. haematobium ova in genital tissue, so-called sandy patches, and bleeding. Prevalence determined by PCR were lower and real-time PCR values were weaker in older women. The presence of Schistosoma DNA may be greater in the recent lesions (e.g., in younger women). For diagnosis in rural areas and in large studies, Schistosoma PCR could become a supplement to gynecologic examinations.

The effects of genital schistosoma haematobium on human papillomavirus and the development of cervical neoplasia after five years in a Zimbabwean population

BACKGROUND

High-risk human papillomavirus (HPV) is responsible for cervical cancer and genital Schistosoma haematobium infection has been hypothesized to be an additional co-factor or even an independent risk factor for cervical neoplasia. The present study aimed to investigate the impact of schistosomiasis on HPV persistence and development of cell atypia in a group of rural Zimbabwean women with confirmed high-risk HPV.

METHODS

A five-year follow-up was done among women previously included in a study on genital schistosomiasis. Women who had high-risk HPV at baseline were invited after 5 years for examination of cell atypia, genital schistosomiasis, and high-risk HPV. Both vaginal lavage samples (low-cost) and cervix brush samples (high-cost) were obtained for further analysis.

RESULTS

Thirty-seven women were re-examined. Genital Schistosoma haematobium of a minimum of five years' duration was associated with the development high-grade squamous intraepithelial neoplasia, but not with persistent high-risk HPV. There was a high concordance between the brush and vaginal lavage (96.3% agreement, kappa 0.93); however, the number of beta-globin negative vaginal lavage samples was unacceptably high.

CONCLUSIONS

Findings warrant an exploration in a larger longitudinal study where a vaginal swab should be explored.

Prevention of gynecologic contact bleeding and genital sandy patches by childhood anti-schistosomal treatment

Schistosoma haematobium infection may cause genital mucosal pathology in women with and without urinary schistosomiasis. This report seeks to explore the long-term effect of anti-schistosomal treatment on the clinical manifestations of S. haematobium infection in the lower genital tract. Prior treatment was reported by 248 (47%) of 527 women. Treatment received before the age of 20 years was significantly associated with the absence of sandy patches and contact bleeding, and this association was independent of current waterbody contact. Treatment in the past five years did not influence the prevalence of gynecologic schistosoma-induced lesions. The study indicates that early treatment may be more efficient for gynecologic morbidity control. Findings warrant an exploration into several chemotherapeutic agents administered at an early age, as well as in adults.

Prevalence of urinary schistosomiasis and HIV in females living in a rural community of Zimbabwe: does age matter?

A cross-sectional study was conducted on 544 women living in Mupfure rural area of Zimbabwe to determine whether infection with urinary schistosomiasis is associated with HIV infection. Schistosoma haematobium infection was examined in urine samples and HIV infection was determined in sera. The prevalence of S. haematobium infection was highest (60%) in women below 20 years of age and declined to 29% in the oldest age group (test for trends, P<0.001). Overall, women infected with urinary schistosomiasis had an HIV prevalence of 33.3%, whilst women without urinary schistosomiasis had an HIV prevalence of 25.6% (chi(2), P=0.053). Women above the age of 35 years and infected with urinary schistosomiasis had a significantly higher HIV prevalence (37.5%) than those without urinary schistosomiasis (16.8%; chi(2), P<0.001).

Genital schistosomiasis in women: a clinical 12-month in vivo study following treatment with praziquantel

Urinary schistosomiasis is known to be associated with lesions in the female genital organs, particularly with the presence of 'sandy patches' in the lower genital tract. This study sought to determine the effect of treatment with praziquantel on gynaecological schistosomiasis in residents of an area endemic for Schistosoma haematobium. A cohort study was conducted among women aged 20-49 years in rural Zimbabwe. The shape and size of lesions were mapped pre treatment and 3 and 12 months following treatment. Ova of S. haematobium were looked for in cytology smears, wet mounts, biopsies, urine and stool. Specimens were collected for detection of sexually transmitted diseases and cancer. At baseline, almost half of the 527 women included in the study had sandy patches. Although urinary ova excretion decreased following treatment (odds ratio 10.3, 95% CI 3.8-27.8, P<0.001), praziquantel treatment was not associated with a significant reduction in genital lesions or contact bleeding (P=0.31-0.94). Sandy patches remained strongly associated with contact bleeding and vessel abnormalities even after treatment. Findings were independent of HIV status. Such lesions, which are common and apparently refractory to treatment for at least 12 months, may be an important risk factor for both the acquisition and transmission of HIV.

Association between genital schistosomiasis and HIV in rural Zimbabwean women

OBJECTIVE

To determine the association between female genital Schistosoma haematobium infection and HIV.

DESIGN AND METHODS

A cross-sectional study with a 1-year follow-up. Gynecological and laboratory investigations were performed for S. haematobium and HIV. Sexually transmitted infections, demographic and urogenital history were analysed as confounders. The participants were 527 sexually active, non-pregnant, non-menopausal women between the ages of 20 and 49 years. The setting was a rural Zimbabwean community where S. haematobium related lesions were found in 46% of the women, HIV in 29% and herpes simplex type- 2 (HSV-2) in 65%.

RESULTS

In permanent residents (>3 years residency), HIV was found in 41% (29/70) of women with laboratory proven genital schistosomiasis as opposed to 26% HIV positive (96/375) in the schistosomal ova negative group [odds ratio (OR), 2.1; 95% confidence interval (CI), 1.2-3.5; P = 0.008. In multivariate analysis S. haematobium infection of the genital mucosa was significantly associated with HIV seropositivity (adjusted OR, 2.9; 95% CI, 1.11-7.5; P = 0.030). All seven women who became HIV positive during the study period (seroincidence 3.1%) had signs of S. haematobium at baseline. In accordance with other studies HIV was significantly associated with HSV-2 (OR, 3.0; 95% CI, 1.7-5.3; P < 0.001), syphilis and human papillomavirus. The highest HIV prevalence (45%) was found in the 25-29 years age group.

CONCLUSION

Women with genital schistosomiasis had an almost three-fold risk of having HIV in this rural Zimbabwean community. Prospective studies are needed to confirm the association.

Simple clinical manifestations of genital Schistosoma haematobium infection in rural Zimbabwean women

Up to 75% of women with urinary schistosomiasis have Schistosoma haematobium ova in the genitals. This study aimed to describe the prevalence of gynecologic S. haematobium infection and to differentiate the disease from sexually transmitted infections (STIs). Gynecologic and laboratory investigations for S. haematobium and STIs were performed in 527 women between the ages of 20 and 49 in rural Zimbabwe. Genital homogenous yellow and/or grainy sandy patches, the commonest type of genital pathology, were identified in 243 (46%) women. Grainy sandy patches were significantly associated with S. haematobium ova only. Genital S. haematobium ova was also significantly associated with homogenous yellow sandy patches, mucosal bleeding, and abnormal blood vessels. The presence of ova was not a predictor for ulcers, papillomata, leukoplakia, polyps, or cell atypia. Mucosal sandy patches seem to be pathognomonic for S. haematobium infection in the female genitals. Coexistence of ova and other lesions may not be causal.

Herpes simplex virus type 2 prevalence of epidemic proportions in rural Zimbabwean women: association with other sexually transmitted infections

INTRODUCTION

Syndromic management of sexually transmitted infections (STIs) is one important strategy in human immunodeficiency virus (HIV) prevention in developing countries, but there is a scarcity of rural community-based data on the relative prevalences of the STIs. We sought to determine the prevalences of the STIs and their clinical correlates in rural Zimbabwean women.

METHODS

A cross-sectional study was conducted among 527 sexually active, non-pregnant, non-menopausal women between the ages of 20 and 49 years.

RESULTS

The seroprevalence for herpes simplex virus type 2 (HSV-2), HIV, trichomoniasis and syphilis were 64.5, 29.3, 24.7 and 6.2% respectively. HSV-2 seropositivity was significantly associated with current non-syphilitic ulcers (adjusted odds ratio [OR] 4.91, 95% confidence interval [CI] 1.08-22.34, p = 0.040). HSV-2 seroprevalence peaked at the age of 35 whereas HIV peaked at 25. The two diseases were strongly associated (OR 2.92, 95% CI 1.85-4.65, p < 0.001).

CONCLUSION

There is evidence of rural epidemics of both HSV-2 and HIV, and a change in the aetiology of genital ulcers in rural Zimbabwe.

Urinary schistosomiasis in Zimbabwean school children: predictors of morbidity

BACKGROUND

The morbid effects of urinary bilharziasis are becoming more evident with the advent of sophisticated diagnostics such as ultrasound. However, such diagnosis of Schistosoma haematobium morbidity is often hampered by lack of funds, proper equipment, or training.

OBJECTIVE

We performed a cross-sectional investigation of schoolchildren in a highly endemic area of east central Zimbabwe in order to assess the utility of a number of simple clinical indicators to predict Schistosoma haematobium morbidity.

METHODS

Prevalence and intensity of S. haematobium infection was determined in 551 schoolchildren, with ultrasound examination of the kidneys and bladder performed on 222. The association of a number of demographic, parasitological, and clinical parameters with clinical outcome was evaluated.

RESULTS

Overall, 60% of the children were infected with S. haematobium . Although lacking specificity, proteinuria and parasite eggs count best predicted bladder pathology. Presence of kidney dilation was associated with fatigue and pain upon urination, but these variables were not very sensitive.

CONCLUSIONS

None of the variables assessed were ideal predictors of morbidity. However, the results suggest that a combination of inexpensive, simple indicators may allow for improved targeting of S. haematobium treatment to those with severe morbidity and better monitoring of the progress of control campaigns when more expensive diagnostic methods are not available.

Human papillomavirus in a rural community in Zimbabwe: The impact of HIV co-infection on HPV genotype distribution

Cervical cancer is a leading cause of cancer-related deaths in developing countries, and the human papillomavirus (HPV) is linked etiologically to cervical cancer. Hence, a vaccine which prevents HPV-associated cervical cancer would have the most impact in developing countries, including the African continent. The type-specific immune response towards HPV virus-like particles, in combination with geographical variation in the prevalence of HPV, necessitates the presence of multiple HPV type antigens in a single vaccine cocktail in order to provide relevant protection. We aimed to investigate whether co-infection with HIV, which is highly prevalent in Africa, plays a role in HPV genotype distribution. After informed consent, HPV detection by GP5+/6+ PCR and HIV detection by serology was carried out on 236 women from the rural north-western part of Zimbabwe. The prevalence of HPV was higher in HIV positive women (54%) than in HIV negative women (27%). Certain HPV types (HPV types 11, 39, 43, 51, and 59, P-values ranging from 0.017 to 0.067) occurred more frequently in HIV positive women. Only high-risk HPV, and not HIV, was associated significantly with cervical intraepithelial neoplasia in multiple regression analysis. In conclusion, a high prevalence of HPV was found in a rural community, where regular Papanicolaou (Pap) smears would be a logistic and economic impossibility, but where free vaccination programmes against other infections are already established. The results suggest that HIV co-infection may have an impact on HPV genotype distribution.

Assessment of eosinophil cationic protein as a possible diagnostic marker for female genital schistosomiasis in women living in a Schistosoma haematobium endemic area

Eosinophil cationic protein (ECP) levels were measured in vaginal lavage extracts from 518 Zimbabwean reproductive women, age range 15-49 years, to assess the potential use of ECP as a diagnostic marker for female genital schistosomiasis (FGS). One hundred and fifty women had confirmed FGS status. These included 77 (cases) women who had ova in genital tissue and 73 (controls) women who had no ova in genital tissue. Participants were examined at baseline, 3 and 15 months post-treatment with praziquantel. ECP levels were determined using the enzyme linked immunosorbent assay (ECP-ELISA). ECP levels from 18 Norwegian women were used to calculate the diagnostic values of the test. FGS was diagnosed from the study population using genital biopsy and smears. Women were also diagnosed for urinary schistosomiasis using the urine filtration technique. The prevalence of urinary schistosomiasis was 39 % at baseline and this declined to 8% and 6% at 3 and 15 month post-treatment surveys, respectively. There was a higher mean ECP level in women with FGS, 889.3 ng/mL (95% CI: 457.0-1327.5) compared to the endemic control group, 359.1 ng/mL (95%, CI: 227.3-490.9), P = 0.027. Mean ECP levels declined at 3 months following treatment of infected individuals. There was no correlation between ECP levels and tissue ova density, and urine egg intensity. The sensitivity, specificity, positive and negative predictive values for the ECP-ELISA test were 35%, 80%, 65% and 53%, respectively. Our results indicate that FGS causes an inflammatory immune response that increases ECP levels in genital fluid. Treatment of schistosomiasis results in a regression of pathology and a decline in ECP levels. However, other factors such as allergy and microbial infection could also be responsible for increased ECP levels in genital mucosa. These conditions will affect the validity of the test in diagnosis of FGS.

Contrasting cellular responses in Schistosoma haematobium infected and exposed individuals from areas of high and low transmission in Zimbabwe

The study compared cytokine profiles of individuals from two areas with different transmission patterns for Schistosoma haematobium. One area was a high transmission (HT) while the other was a low transmission (LT) area for S. haematobium. Observations on cellular immune responses were made on stimulated peripheral blood mononuclear cells (PBMC), which were collected pre-treatment, then at 12 and 18 months post treatment. Stimulation was with schistosome worm and egg antigens and a mitogen, phaetohaemaglutinin (PHA). Observations were made on PBMC proliferation and the profiles of cytokine produced over a 5-day incubation period. The two distinct areas showed significant differences on both levels of proliferation and cytokine production for all the measured classes (IL-4, IL-5, IL-10 and IFN-gamma). PBMC from individuals from the LT area had high levels of proliferation but low cytokine production to both antigen stimulants while PBMC from individuals from the HT area showed low levels of proliferation but high cytokine production levels. Prior to treatment, individuals not excreting schistosome ova in the HT area had higher levels of proliferation to the stimulants, than the infected individuals. However, after treatment re-infected individuals showed high levels of proliferation. Before treatment, both infected and uninfected groups showed low and similar ratios, respectively, of IL-4:IFN-gamma, IL-5:IFN-gamma and IL-10:IFN-gamma, while IFN-gamma was high in the infected individuals. After treatment the non re-infected had higher levels of IL-4, IL-5 and IL-10, with the infected having high levels of IFN-gamma. Th1-like response dominated during infection with the Th2-like responses dominating post treatment and in uninfected individuals. The results indicated that the cytokine balance determines, in part, susceptibility or resistance to S. haematobium infection.

Reference values and predictors of white blood cell subset counts: a cross-sectional study among HIV seronegative pregnant women in Zimbabwe

OBJECTIVE

To identify predictors and develop reference values of white blood cell subset counts for pregnant black women in Zimbabwe.

STUDY DESIGN

In this cross-sectional study, multiple linear regression (MLR) analysis was employed to assess the relationship of WBC subset counts with age, gestational age, gravidity, season, serum retinol, beta-carotene, ferritin, folate and alpha-1 antichymotrypsin among 998 women 22-35 weeks pregnant attending antenatal care (ANC) in Harare, Zimbabwe.

RESULTS

Mean age was 24.0 (95% CI; 23.6-24.4), range 14-45 years. The mean gestational age was 29.2 (95% CI; 29.0-29.4), range 22-35 weeks. Median gravidity was 2, range 1-9. Predictors of neutrophil counts were gestational age, season and serum ferritin, the latter in interaction with gravidity (interaction, p = 0.016). Mean lymphocyte count was 0.13 x 10(9)cells/l higher in gravida >4 than gravida 1-3, and 0.35 x 10(9)cells/l higher in the late rainy than other seasons. Predictors of monocyte counts were gestational age, serum folate and season, while eosinophil counts declined with advancing gestation. Reference values adjusted or unadjusted for identified predictors were different from those of pregnant and non-pregnant white women reported in the literature.

CONCLUSIONS

Gravidity, season and micronutrient status influence WBC counts during pregnancy and therefore are of physiological and clinical importance. WBC reference values in the literature were not applicable obviating the need for local reference values.

Urinary tract pathology attributed to Schistosoma haematobium: does parasite genetics play a role?

Disease outcome in persons infected with Schistosoma haematobium varies dramatically, ranging from mild symptoms to severe damage of the kidneys and/or bladder. We used ultrasonography to characterize the extent of urinary tract pathology of infected children in Zimbabwe, and random genetic markers to examine the relationship between genetic diversity of S. haematobium and clinical outcome. One hundred thirty-three parasite isolates from 12 students with mild lesions and 13 with severe lesions were compared. Using four randomly amplified polymorphic DNA (RAPD) markers, we scored parasite allelic frequencies at 53 loci. Although parasite heterogeneity did not differ, allelic frequencies at eight loci differed significantly between the mild and severe groups. Parasite isolates were analyzed further using a modified cluster analysis that segregated the population into 13 clusters of associated genotypes. Three clusters were significantly over-represented in children with severe lesions. Our findings, although preliminary, suggest that parasite genetic associations may be important in clinical outcome.

Epidemiological assessment of Schistosoma haematobium-induced kidney and bladder pathology in rural Zimbabwe

Clinical outcome of Schistosoma haematobium infection may vary significantly, ranging from mild symptoms to severe damage of urinary tract organs. This present study was undertaken to assess the relationship of a number of epidemiological and parasitological parameters with disease outcome in children from rural Zimbabwe. We surveyed 551 primary school students from three schools in the Chikwaka Communal Lands for schistosomiasis; 59.7% were infected with S. haematobium. Ultrasound examination of 189 of the infected students revealed that 50% had pathological changes of their bladder and 36% had abnormal pyelon dilation of at least one of their kidneys. Intensity of infection, certain water contact behaviours, male gender, proteinuria, and self-perceived haematuria were associated with increased bladder damage. Strenuous playing was negatively associated with pathology, especially for those with the highest grade of bladder damage. Kidney pathology was significantly linked with fatigue and pain upon urination and was more prevalent in students from schools closest to the major river systems. Our findings suggest that pathology due to urinary schistosomiasis is widespread and symptomatic in this population. The associations with bladder and kidney pathology can be used to predict disease severity and may be useful in targeting treatment to those most at risk.

The effect of treatment on the age-antibody relationship in children infected with Schistosoma mansoni and Schistosoma haematobium

The effect of praziquantel treatment on the age-antibody relationship was studied in 174 children aged between 6 and 17 years from a schistosome endemic area in Zimbabwe. The children were co-infected with Schistosoma mansoni and S. haematobium with infection prevalences of 74% and 53% respectively. Antibody levels for the isotypes IgA, IgE, IgM, IgG1, IgG2, IgG3 and IgG4, directed against soluble egg antigen were measured using an indirect ELISA assay. Treatment resulted in a significant increase in levels of IgG2 and IgG3 while levels of IgA decreased significantly. In untreated children there were significant decreases in levels of IgG4. Treatment also resulted in significant alteration in the age-antibody profiles for the isotypes IgE, IgM, IgG1 and IgG2 in treated children but not in untreated children. The results are discussed in the context of factors believed to give rise to the age-antibody relationship; i.e. age-related exposure patterns, age-related development of acquired immunity, age-related hormonal changes and age-related changes in innate susceptibility to infection.

Chemotherapy-induced, age-related changes in antischistosome antibody responses

Humoral responses directed against Schistosoma mansoni soluble egg antigen were studied in Zimbabwean children before and after treatment with either praziquantel (PZQ) or oxamniquine (OXAM). Treated children showed a significant increase in the proportion producing IgE and IgG3 and in mean levels of IgE, IgM, IgG3 six weeks post-treatment. At 18 weeks post-treatment, the proportion of treated children producing IgA, IgE, and IgG3 increased while the proportion producing IgG1 and IgG4 decreased. Mean levels of IgA, IgE, and IgG3 were higher than pre-treatment levels while levels of IgG1, IgG4 and IgM were lower. Statistical analyses showed that the magnitude of change in levels of IgE, IgM and IgG3 at 6 weeks post-treatment and of IgE, IgG3 and IgG4 at 18 weeks post-treatment was significantly greater in treated compared to untreated children, and there were no significant differences in immune responses between children treated with praziquantel and those treated with oxamniquine. The magnitude of change in IgE at 6 and 18 weeks, IgM at 6 weeks and IgG3 at 18 weeks post-treatment were significantly associated with age in treated but not in untreated children, with the change being greater in younger children. This suggests that treatment induced a change in the age-antibody relationship for these isotypes, and that the age-antibody relationship is not robust to chemotherapy. Pre-treatment infection levels were significantly associated (positive correlation) with the magnitude of change for IgE and IgG3 at 18 weeks post-treatment. Taken together, these results indicate that the age-antibody relationship observed in these children is due, at least in part, to cumulative host experience of parasite antigens and not host age alone.

T cell clones from Schistosoma haematobium infected and exposed individuals lacking distinct cytokine profiles for Th1/Th2 polarisation

T cell clones were derived from peripheral blood mononuclear cells of Schistosoma haematobium infected and uninfected individuals living in an endemic area. The clones were stimulated with S. haematobium worm and egg antigens and purified protein derivative. Attempts were made to classify the T cell clones according to production of the cytokines IL-4, IL-5 and IFN-gamma. All the T cell clones derived were observed to produce cytokines used as markers for the classification of Th1/Th2 subsets. However, the 'signature' cytokines marking each subset were produced at different levels. The classification depended on the dominating cytokine type, which was having either Th0/1 or Th0/2 subsets. The results indicated that no distinct cytokine profiles for polarisation of Th1/Th2 subsets were detected in these S. haematobium infected humans. The balance in the profiles of cytokines marking each subset were related to infection and re-infection status after treatment with praziquantel. In the present study, as judged by the changes in infection status with time, the T cell responses appeared to be less stable and more dynamic, suggesting that small quantitative changes in the balance of the cytokines response could result in either susceptibility or resistant to S. haematobium infection.

The impact of repeated treatment with praziquantel of schistosomiasis in children under six years of age living in an endemic area for Schistosoma haematobium infection

Praziquantel was given every eight weeks for two years to children aged under six years of age, living in a Schistosoma haematobium endemic area. Infection with S. haematobium and haematuria were examined in urine and antibody profiles (IgA, IgE, IgM, IgG1, IgG2, IgG3, and IgG4) against S. haematobium adult worm and egg antigens were determined from sera collected before each treatment. Chemotherapy reduced infection prevalence and mean intensity from 51.8% and 110 eggs per 10 ml urine, respectively, before starting re-treatment programme to very low levels thereafter. Praziquantel is not accumulated after periodic administration in children. Immunoglobulin levels change during the course of treatment with a shift towards 'protective' mechanisms. The significant changes noted in some individuals were the drop in 'blocking' IgG2 and IgG4 whereas the 'protecting' IgA and IgG1 levels increased. The antibody profiles in the rest of the children remained generally unchanged throughout the study and no haematuria was observed after the second treatment. The removal of worms before production of large number of eggs, prevented the children from developing morbidity.

Cytokine responses to mitogen and Schistosoma haematobium antigens are different in children with distinct infection histories

Prevalence of Schistosoma haematobium infection in children from two neighbouring villages in Zimbabwe was 77.1% and 40.3%, respectively. The age-intensity data indicated peak intensities of infection at a lower age in the high prevalence village. This study investigated whether the difference in infection histories was reflected in a difference in cytokine profiles between children resident in these two villages. Blood samples were taken to assay for cytokine secretion 1 year after treatment for schistosomiasis. They were cultured with phytohaemagglutinin (PHA), schistosome egg antigens (SEA) or cultured without stimulant and tested for the presence of interleukin (IL)-4, IL-5, IL-10, granulocyte-macrophage colony-stimulating factor (GM-CSF) and IFN-gamma. Blood samples from children from the low prevalence village were more likely to produce IL-4 (P < 0.0001) and produced higher levels of IFN-gamma (P < 0.02) and GM-CSF (P < 0.03) when cultured with PHA for 24 h. Residence in the high prevalence village was associated with production of IL-10 (P < 0.006) and GM-CSF (P < 0.04) in response to culture with SEA and IL-5 (P < 0.02) with PHA for 48 h. The interaction between age and village was not significant for these results; however, there was a significant interaction between age and village for IL-5 detected in blood samples cultured with PHA for 24 h (P < 0.01). These results concur with previous observations that major patterns of cytokine production can be related to immunosuppression, but also indicate an underlying pattern which reflects the importance of history of infection to the immune response.

Dissociation of interleukin-4 and interleukin-5 production following treatment for Schistosoma haematobium infection in humans

Infection with Schistosoma haematobium, the causative agent of urinary schistosomiasis is characterized by high levels of specific immunoglobulin (Ig) E and eosinophilia. The primary cytokines driving production of IgE and eosinophilia are IL-4 and IL-5, respectively. In this study, IL-4 and IL-5 production in children from a schistosome endemic area of Zimbabwe were investigated. Blood samples were taken, stimulated in vitro with either mitogen or schistosome antigens and assayed for IL-4 and IL-5 production. These samples produced either IL-4 or IL-5 but rarely both cytokines when blood was cultured in vitro for 24 or 48 h. After 72 h culture in vitro, both cytokines were detected in most samples. These data imply that while IL-4 and IL-5 are both produced by schistosome infected people, they are not necessarily coproduced.

Anti-schistosome antibody responses in children coinfected with malaria

People residing in schistosome endemic areas are often infected with other parasites. The interaction of the parasites in the host has important implications in the development of acquired immunity to schistosomiasis, and schistosome immuno-epidemiology. An analysis of specific anti-schistosome egg responses in children coinfected with schistosomiasis and malaria shows that malaria positive children produce significantly more anti-schistosome IgE and IgG3 than schistosome infected children who are negative for malaria.

Exposure, infection and immune responses to Schistosoma haematobium in young children

Behavioural, parasitological and immunological data were obtained from 48 children up to 6 years old, resident in a Schistosoma haematobium endemic area in Zimbabwe. The children averaged more than 1 contact with infective water bodies every 3 days and all showed immunological evidence of exposure (an anti-cercarial and/or anti-egg antibody response). IgM was the dominant isotype and appeared in the youngest children, followed by IgA, IgE and IgG3. However, only 38 children showed evidence of infection (an anti-egg response or eggs in urine) and only 14 were excreting eggs. The best estimates from these data are that less than 1 in 100 contacts results in infection and less than 1 in 1000 result in egg output. This suggests that there may be substantial attrition of invading cercaria even in naïve individuals.

A comparison of re-infection rates with Schistosoma haematobium following chemotherapy in areas with high and low levels of infection

Two groups of children (6-15 years) from a Schistosoma haematobium endemic area were followed for 9 months after praziquantel treatment. Seventy-three children came from an area of high infection while 67 children came from an area of low infection. Pre-treatment infection prevalence in the high infection area (76.6%) was significantly higher than that in low infection area (36.3%). Levels of anti-SEA immunoglobulin (Ig)A and IgM were significantly higher and levels of IgG3 significantly lower in children from the low infection area. Nine months after treatment, infection prevalence was significantly higher in the high infection area (29.0%) (where re-infection rates were higher) than in the low infection area (12.9%). Children from the high infection area were six times more likely to get re-infected than those from the low infection area, while younger children were 30 times more likely to get re-infected than older children. These results are discussed in relation to differences in transmission and the development of acquired immunity. Pre-treatment levels of IgM and the difference between IgE and IgG4 were positively associated with re-infection in the high infection area. These results are discussed in relation to the interpretation of simple correlations between infection and some antibody levels and the inference of causal relationships between observed epidemiological and immunological patterns.

Changes in specific anti-egg antibody levels following treatment with praziquantel for Schistosoma haematobium infection in children

Fifty-seven children 6-15 years old resident in a Schistosoma haematobium endemic area in eastern Zimbabwe were treated with praziquantel at 40 mg/kg body weight. Levels of IgA, IgE, IgG1, IgG2, IgG3, IgG4, and IgM antibodies against soluble egg antigen (SEA) were assayed by ELISA before treatment and at 18 and 36 weeks following treatment. Prevalence of infection (as determined by urine egg counts) was 65% before treatment, all children were confirmed egg negative six weeks after treatment, and reinfection prevalence was 4% at 18 weeks and 21% at 36 weeks after treatment. At 18 weeks after treatment, there was a massive increase in IgG1 levels and significant increases in IgE and IgG4 levels and significant decreases in IgA and IgG2 levels. Similar patterns occurred at 36 weeks after treatment. Egg positive children showed a more marked increase in IgG1 and (for older children) a more marked decrease in IgG2 levels. There were no other effects of age or sex. IgA and IgG1 levels fell significantly between 18 and 36 weeks following treatment but not to pretreatment levels. The results show that specific anti-egg antibody responses are highly sensitive to the effects of praziquantel treatment. A possible consequence is that the susceptibility of children to infection with S. haematobium is altered by chemotherapy; this requires further investigation.

Heterogeneities in schistosome transmission dynamics and control

We review the theoretical framework for exploring the impact of individual and spatial heterogeneities in patterns of exposure and contamination and on the basic reproduction number, R0, for human schistosomes. Analysis of water contact data for 5 communities in Zimbabwe and Mali suggests that the impact is substantial, increasing R0 by factors of up to 6.5, mostly due to highly overdispersed distributions of contact rates among individuals. Several practical conclusions emerge: concentration of contacts at a single site should be avoided; the impact of control targeted at certain sites cannot be predicted without knowledge of how individuals' contacts are distributed among sites; control programmes targeted at individuals or sites contributing most to transmission can be very efficient but, conversely, will be ineffective if any of these individuals or sites are missed.

Chemotherapy accelerates the development of acquired immune responses to Schistosoma haematobium infection

Treatment of 41 Schistosoma haematobium-infected children, 5-16 years old, with the drug praziquantel induced a switch from a predominantly IgA-specific antibody response to a predominantly IgG1 response within 12 weeks. A cross-sectional survey suggests that the same switch occurs naturally, but over several years, as children age (n = 251). The switch may be driven by alterations in cytokine levels in response to the release of antigens by dead or damaged parasites. Adults are more resistant to schistosome infection than children, and the switch to an "adult" response suggests that praziquantel treatment may have an immunizing effect, with benefits extending beyond a transient reduction in levels of infection.

A comparison of humoral responses to Schistosoma haematobium in areas with low and high levels of infection

Antibody responses to Schistosoma haematobium of 280 Zimbabweans were studied in two areas of differing infection levels. 133 of the subjects came from a low infection area with a prevalence of 33.8% and geometric mean infection intensity of 0.8 eggs per 10ml of urine, while 147 of the subjects came from a high infection area with a prevalence of 62.7% and geometric mean intensity of 3.2 eggs per 10 ml of urine. Both the age-prevalence and age-intensity curves exhibited a peak shift. IgA, IgE, IgG, IgG1, IgG2, IgG3, IgG4, and IgM antibody levels against soluble egg antigen (SEA) and whole worm homogenate (WWH) were assayed by ELISA. Females produced significantly more anti-SEA IgG1, IgG4, IgM, anti-WWH IgE and IgG1. People from the high infection area produced significantly more anti-SEA IgE, IgG3 and anti-WWH IgG3 and significantly lower levels of anti-SEA IgA, IgM and anti-WWH IgM when the effects of infection intensity, sex and age had been allowed for. The age profiles of anti-SEA IgA, IgG and anti-WWH IgA and IgM reflected current levels of infection while anti-WWH IgG1, IgG2 and anti-SEA IgG1 evolved more slowly with age, and anti-WWH IgE rose with age in both areas. Some antibody responses, anti-SEA/WWH IgM, anti-SEA IgG1 and possibly anti-SEA/ WWH IgA showed different age profiles in the two areas, with changes in antibody levels occurring at a younger age in the high infection area suggesting that immune responses are evolving more rapidly in residents of this area. This result clearly demonstrates that antibody levels are not a function of age alone.

Heterogeneities in the transmission of infectious agents: implications for the design of control programs

From an analysis of the distributions of measures of transmission rates among hosts, we identify an empirical relationship suggesting that, typically, 20% of the host population contributes at least 80% of the net transmission potential, as measured by the basic reproduction number, R0. This is an example of a statistical pattern known as the 20/80 rule. The rule applies to a variety of disease systems, including vector-borne parasites and sexually transmitted pathogens. The rule implies that control programs targeted at the "core" 20% group are potentially highly effective and, conversely, that programs that fail to reach all of this group will be much less effective than expected in reducing levels of infection in the population as a whole.