Seasonal variations in Schistosoma haematobium egg excretion in school-age girls in rural KwaZulu-Natal Province, South Africa.

BACKGROUND: A predominant feature of Schistosoma haematobium infection is urinary egg excretion, and microscopic egg detection remains the accepted standard field diagnostic tool. Praziquantel is the drug of choice for schistosomiasis, and the World Health Organization recommends that it should be administered to all children >4 years of age living in schistosomiasis-endemic areas. The frequency of mass drug administration depends on the prevalence rate in the community. Urinary schistosome egg output has a day-to-day and hour-to-hour intrasubject variation. Therefore, it is important to assess possible seasonal variations in egg excretion to improve the planning of drug treatment. OBJECTIVES: To assess the influence of seasonality on urinary schistosome egg excretion in South Africa (SA). METHODS: We performed a prospective cohort study, exploring seasonal variations of S. haematobium egg excretion in 184 girls aged 10 - 12 years from randomly selected schools in a rural area of KwaZulu-Natal Province, SA. The area has a subtropical climate characterised by a cool dry season and a hot humid season. For children, water contact is higher in the latter season. At baseline, 108 girls were examined in the hot season, and 76 in the cold season. In the next year's cold season the untreated patients were re-investigated before treatment. RESULTS: There was a decrease in infection in the group initially tested in the hot season compared with the group tested in the cold season at both time points when adjusted for age and water contact (adjusted odds ratio 3.61 (95% confidence interval 1.14 - 11.44); p=0.03). CONCLUSIONS: This unique study shows that schistosomiasis prevalence determined by microscopy exhibits seasonal variation, with a higher prevalence in the hot rainy season. Precise community prevalence estimations are key in decisions to treat communities. There was significantly lower egg output in the cold season, and sampling in that season may therefore underestimate the prevalence of urinary schistosomiasis. The study indicates that sampling in SA should be done in the hot season.

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

Following publication of the original article [1], one of the authors reported that his name had been spelled incorrectly. It should be Galappaththi-Arachchige, not Galapaththi-Arachchige.

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 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.

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).

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.

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.

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.

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.

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 percent 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

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

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.

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.

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.

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.