Urogenital schistosomiasis and soil-transmitted helminthiasis (STH) in Cameroon: An epidemiological update at Barombi Mbo and Barombi Kotto crater lakes assessing prospects for intensified control interventions

BACKGROUND

The crater lakes of Barombi Mbo and Barombi Kotto are well-known transmission foci of schistosomiasis and soil-transmitted helminthiasis having had several important control initiatives previously. To collect contemporary epidemiological information, a cross-sectional survey was undertaken inclusive of: signs and symptoms of disease, individual treatment histories, local water, sanitation and hygiene (WASH)-related factors and malacological surveillance, with molecular characterisation of specimens.

METHODS

At each lake, a community cross-sectional survey was undertaken using a combination of stool and urine parasitological sampling, and interview with pro-forma questionnaires. A total of 338 children and adults participated. Material from snail and parasite species were characterised by DNA methods.

RESULTS

Egg-patent prevalence of urogenital schistosomiasis was 8.7% at Barombi Mbo (all light-intensity infections) and 40.1% at Barombi Kotto (21.2% heavy-intensity infections). Intestinal schistosomiasis was absent. At Barombi Kotto, significantly more women reported signs and symptoms associated with female genital schistosomiasis. While there had been extensive recent improvement in WASH-related infrastructure at Barombi Mbo, water contact risk scores were higher among schistosomiasis-infected participants (P < 0.001) and at Barombi Kotto in general (P < 0.001). Across both lakes, mean prevalence of STH was very low (6.3%) evidencing an impressive decrease of 79.0% over the last decade; neither Strongyloides stercoralis nor Ascaris lumbricoides were found. A total of 29 freshwater sampling sites were inspected for snails, 13 in Barombi Mbo and 16 in Barombi Kotto; water chemistry differed significantly (P < 0.0001) between lakes for both mean pH (7.9 v. 9.6) and mean conductivity (64.3 μS v. 202.1 μS) respectively. Only two Bulinus camerunensis found on the central island of Barombi Kotto were observed to shed schistosome cercariae, but schistosome DNA was later detected in Bulinus sampled from both lakes as well as in Indoplanorbis exustus, an invasive species from Asia.

CONCLUSIONS

STH is currently at very low levels while urogenital schistosomiasis is of greatest concern at Barombi Kotto. This assessment highlights a unique opportunity for further study of the epidemiological dynamics at these crater lakes, to evaluate future intensified interventions both in terms of gaining and sustaining control at Barombi Kotto or in moving towards local interruption of transmission of both diseases at Barombi Mbo.

Towards interruption of schistosomiasis transmission in sub-Saharan Africa: developing an appropriate environmental surveillance framework to guide and to support 'end game' interventions

Schistosomiasis is a waterborne parasitic disease in sub-Saharan Africa, particularly common in rural populations living in impoverished conditions. With the scale-up of preventive chemotherapy, national campaigns will transition from morbidity- to transmission-focused interventions thus formal investigation of actual or expected declines in environmental transmission is needed as 'end game' scenarios arise. Surprisingly, there are no international or national guidelines to do so in sub-Saharan Africa. Our article therefore provides an introduction to key practicalities and pitfalls in the development of an appropriate environmental surveillance framework. In this context, we discuss how strategies need to be adapted and tailored to the local level to better guide and support future interventions through this transition. As detection of egg-patent infection in people becomes rare, careful sampling of schistosome larvae in freshwater and in aquatic snails with robust species-specific DNA assays will be required. Appropriate metrics, derived from observed prevalence(s) as compared with predetermined thresholds, could each provide a clearer insight into contamination- and exposure-related dynamics. Application could be twofold, first to certify areas currently free from schistosomiasis transmission or second to red-flag recalcitrant locations where extra effort or alternative interventions are needed.

A public health framework for addressing black and white disparities in preterm delivery

The Healthy People 2010 objectives call for the elimination of racial disparities in health, along with reductions in several multifactorial perinatal outcomes. Evidence-based interventions have been the focus of discussion to date. We propose a 6-component framework based on knowledge from the social, medical, psychological, and epidemiological literatures to guide development of interventions to reduce preterm delivery and eliminate disparities. Pilot testing and rigorous evaluation of the interventions developed from this framework are encouraged.

Opportunities for intervention: discussing physical abuse during prenatal care visits

BACKGROUND

The American Academy of Pediatrics and the American College of Obstetricians and Gynecologists recommend that screening for physical abuse during prenatal care visits becomes routine. Although prenatal care visits offer a unique intervention opportunity, screening is not yet standard practice.

DATA AND METHODS

We used data from the 1996 and 1997 Pregnancy Risk Assessment Monitoring System (PRAMS) to assess the prevalence of and the factors associated with health care providers' discussion of physical abuse with pregnant women in 14 states. PRAMS is a state-specific, population-based surveillance system that collects information from women on maternal behaviors before and during pregnancy, and at 2 to 6 months postpartum.

RESULTS

Between 22% and 39% of the women surveyed reported that health care providers talked with them about physical abuse during prenatal care visits. Health care providers were more likely to discuss physical abuse with women who were black, Hispanic, young (aged <20 and 20 to 29), had a high school education or less, or paid for prenatal care with Medicaid.

CONCLUSIONS

Our results indicate that most pregnant women do not report that their prenatal care providers discussed physical abuse with them. Logistic regression analyses identified consistent associations across the 14 states between discussion of abuse and demographic and pregnancy-related factors. A better understanding of the factors associated with whether a health care provider discusses physical abuse with a pregnant woman could increase intervention opportunities.