Re-visiting Trichuris trichiura intensity thresholds based on anemia during pregnancy.

BACKGROUND: The intensity categories, or thresholds, currently used for Trichuris trichiura (ie. epg intensities of 1-999 (light); 1,000-9,999 epg (moderate), and ≥ 10,000 epg (heavy)) were developed in the 1980s, when there were little epidemiological data available on dose-response relationships. This study was undertaken to determine a threshold for T. trichiura-associated anemia in pregnant women and to describe the implications of this threshold in terms of the need for primary prevention and chemotherapeutic interventions. METHODOLOGY/PRINCIPAL FINDINGS: In Iquitos, Peru, 935 pregnant women were tested for T. trichiura infection in their second trimester of pregnancy; were given daily iron supplements throughout their pregnancy; and had their blood hemoglobin levels measured in their third trimester of pregnancy. Women in the highest two T. trichiura intensity quintiles (601-1632 epg and ≥ 1633 epg) had significantly lower mean hemoglobin concentrations than the lowest quintile (0-24 epg). They also had a statistically significantly higher risk of anemia, with adjusted odds ratios of 1.67 (95% CI: 1.02, 2.62) and 1.73 (95% CI: 1.09, 2.74), respectively. CONCLUSIONS/SIGNIFICANCE: This analysis provides support for categorizing a T. trichiura infection ≥ 1,000 epg as 'moderate', as currently defined by the World Health Organization. Because this 'moderate' level of T. trichiura infection was found to be a significant risk factor for anemia in pregnant women, the intensity of Trichuris infection deemed to cause or aggravate anemia should no longer be restricted to the 'heavy' intensity category. It should now include both 'heavy' and 'moderate' intensities of Trichuris infection. Evidence-based deworming strategies targeting pregnant women or populations where anemia is of concern should be updated accordingly.

Trichuris and hookworm infections associated with anaemia during pregnancy.

OBJECTIVE: To assess the following associations between the second and third trimesters of pregnancy: (i) the intensity of soil-transmitted helminth (STH) infection and haemoglobin/anaemia, (ii) the effect of mebendazole treatment on the occurrence of STH infection, and (iii) the effect of mebendazole treatment on haemoglobin/anaemia. METHODS: Data originated from a trial of 1042 pregnant women recruited in their second trimester and followed to delivery. Baseline assessments included socio-demographic/health information from questionnaires, haemoglobin/anaemia from HemoCue ascertainment of fingerprick blood, and the presence and intensity of STH (Ascaris lumbricoides, hookworms and Trichuris trichiura) infections from Kato-Katz examination. All women were given iron supplements; half were randomly allocated to receive single dose 500 mg mebendazole, and half, placebo. Haemoglobin/anaemia and STH infection status were determined again in the third trimester of pregnancy. RESULTS: Complete information was available from 935 (89.7%) women. Mebendazole significantly reduced the prevalence and intensity of all three STH infections. Higher intensities of hookworm and Trichuris infections in the second trimester were associated with a higher risk of anaemia in the third trimester. Overall, women with moderate/heavy Trichuris infection were found to be at a higher risk of anaemia; the highest risk was observed among those with moderate/heavy hookworm co-infection (adjusted OR = 2.77; 95% CI: 1.26, 6.11). Mebendazole treatment did not reduce the risk of anaemia. CONCLUSION: Higher intensities of both Trichuris and hookworm infections are associated with anaemia in pregnancy. The importance of Trichuris infections during pregnancy requires renewed attention.

System-level determinants of immunization coverage disparities among health districts in Burkina Faso: a multiple case study.

BACKGROUND: Despite rapid and tangible progress in vaccine coverage and in premature mortality rates registered in sub-Saharan Africa, inequities to access remain firmly entrenched, large pockets of low vaccination coverage persist, and coverage often varies considerably across regions, districts, and health facilities' areas of responsibility. This paper focuses on system-related factors that can explain disparities in immunization coverage among districts in Burkina Faso. METHODS: A multiple-case study was conducted of six districts representative of different immunization trends and overall performance. A participative process that involved local experts and key actors led to a focus on key factors that could possibly determine the efficiency and efficacy of district vaccination services: occurrence of disease outbreaks and immunization days, overall district management performance, resources available for vaccination services, and institutional elements. The methodology, geared toward reconstructing the evolution of vaccine services performance from 2000 to 2006, is based on data from documents and from individual and group interviews in each of the six health districts. The process of interpreting results brought together the field personnel and the research team. RESULTS: The districts that perform best are those that assemble a set of favourable conditions. However, the leadership of the district medical officer (DMO) appears to be the main conduit and the rallying point for these conditions. Typically, strong leadership that is recognized by the field teams ensures smooth operation of the vaccination services, promotes the emergence of new initiatives and offers some protection against risks related to outbreaks of epidemics or supplementary activities that can hinder routine functioning. The same is true for the ability of nurse managers and their teams to cope with new situations (epidemics, shortages of certain stocks). CONCLUSION: The discourse on factors that determine the performance or breakdown of local health care systems in lower and middle income countries remains largely concentrated on technocratic and financial considerations, targeting institutional reforms, availability of resources, or accessibility of health services. The leadership role of those responsible for the district, and more broadly, of those we label "the human factor", in the performance of local health care systems is mentioned only marginally. This study shows that strong and committed leadership promotes an effective mobilization of teams and creates the conditions for good performance in districts, even when they have only limited access to supports provided by external partners. ABSTRACT IN FRENCH: See the full article online for a translation of this abstract in French.

A double-blind randomized controlled trial of antenatal mebendazole to reduce low birthweight in a hookworm-endemic area of Peru.

OBJECTIVE: To assess the effect on birthweight of antenatal mebendazole plus iron vs. placebo plus iron in a highly hookworm-endemic area. METHODS: Double-blind, randomized controlled trial set in rural and peri-urban communities in the Peruvian Amazon region. A total of 1042 second trimester pregnant women between the ages of 18 and 44 years were recruited from April to November 2003, and followed to July 2004. Women were randomly assigned to receive either mebendazole (500 mg single dose) plus iron supplements (60 mg elemental iron daily) or placebo plus iron supplements. The primary outcome was mean infant birthweight and secondary measures included proportion of low birthweight babies and maternal anaemia. RESULTS: The prevalence of hookworm infection was 47.5%. There were no differences between intervention groups in mean birthweight (3104 g vs. 3090 g, P = 0.629), proportion of low birthweight (<2500 g; 8.1%vs. 8.7%, P = 0.755) or maternal anaemia in the third trimester [33.0% (158/479) vs. 32.3% (152/471), P = 0.815]. However, the proportion of very low birthweight (<1500 g) was significantly lower in the mebendazole group [0% (0/479) vs. 1.5% (7/471), P = 0.007]. CONCLUSIONS: This trial provides additional evidence for the use of anthelmintics, over and above iron supplementation, within antenatal care programmes in hookworm-endemic areas. Benefits of de-worming may be higher in countries not having an antenatal iron supplementation programme or where intensity of hookworm infections is higher.

Lack of risk of adverse birth outcomes after deworming in pregnant women.

BACKGROUND: Pregnant women who live in hookworm-endemic areas may benefit from deworming during their pregnancy. The benefit derives from reducing anemia, primarily iron-deficiency anemia caused by hookworm infection-attributable blood loss. Where the prevalence of hookworm is more than 20% to 30%, the World Health Organization recommends that pregnant women receive anthelminthic treatment (mebendazole, albendazole, levamisole or pyrantel) after their first trimester. The objective of this study is to report, describe and compare the occurrence of adverse birth outcomes in a large randomized, controlled trial of antenatal mebendazole (500 mg single dose) plus iron supplements versus placebo plus iron supplements conducted between April 2003 and June 2004 in the Amazon region of Peru. METHODS: Physician-recorded data on adverse birth outcomes occurring during the trial (N = 1042) were obtained. Proportions were compared using chi analysis. RESULTS: No statistically significant difference (P = 0.664) was found between the mebendazole group and the placebo group in terms of numbers of miscarriages, malformations, stillbirths, early neonatal deaths and premature babies (28 versus 31, respectively). CONCLUSIONS: The evidence provided by this large randomized, controlled trial of mebendazole administered during pregnancy indicates that deworming with mebendazole can be safely included in antenatal care programs in hookworm-endemic areas.

Should deworming be included in antenatal packages in hookworm-endemic areas of developing countries?

BACKGROUND: WHO recommends antenatal (after the first trimester) deworming for pregnant women who live in areas where the prevalence of hookworm infection exceeds 20-30%. However, deworming has not been included in antenatal care packages in most developing countries. METHODS: A review of articles publishing original data identified primarily through Medline was conducted using subject heading terms and text words for "deworming", "pregnant women", "hookworm", "anthelminthic", "anthelmintic", "albendazole", "mebendazole", "pregnancy" and their combinations. Bibliographies of retrieved articles were scanned to identify any additional relevant documents. RESULTS: Five articles examined the benefits of antenatal deworming. All provided evidence favourable to deworming, in terms of both maternal and infant outcomes. Comparison of outcome measures could be improved with a more standardized approach to outcome ascertainment and reporting. CONCLUSION: The evidence base for the inclusion of deworming in antenatal care packages in hookworm-endemic areas is mostly observational in nature. Future research should be directed towards 1) strengthening the evidence base with empirical data from randomized controlled trials, and 2) furthering our understanding related to government uptake of the WHO policy on deworming.

Relationship between intensity of soil-transmitted helminth infections and anemia during pregnancy.

A direct relationship exists between the intensity of hookworm infection and blood loss. Other parasites may also contribute to blood loss. Our objective was to assess the relationship between the intensity of soil-transmitted helminth infections and anemia in pregnant women in a highly endemic area of Peru. Recruitment occurred between April and November 2003. Overall, 47.31% of 1,042 women had anemia (hemoglobin < 11 g/dL), 47.22% were infected with hookworm and 82.25% with Trichuris. Prevalences of infections were not associated with anemia. However, those infected with moderate and heavy intensities of hookworm infection (OR = 1.84; 95% CI: 1.06, 3.17) and those with moderate and heavy intensities of both hookworm and Trichuris infections (OR = 2.13; 95% CI: 1.10, 4.13) were more likely to suffer from anemia than women having no or light intensities. These results support routine anthelminthic treatment within prenatal care programs in highly endemic areas.