New approaches to measuring anthelminthic drug efficacy: parasitological responses of childhood schistosome infections to treatment with praziquantel

By 2020, the global health community aims to control and eliminate human helminthiases, including schistosomiasis in selected African countries, principally by preventive chemotherapy (PCT) through mass drug administration (MDA) of anthelminthics. Quantitative monitoring of anthelminthic responses is crucial for promptly detecting changes in efficacy, potentially indicative of emerging drug resistance. Statistical models offer a powerful means to delineate and compare efficacy among individuals, among groups of individuals and among populations.; We illustrate a variety of statistical frameworks that offer different levels of inference by analysing data from nine previous studies on egg counts collected from African children before and after administration of praziquantel.; We quantify responses to praziquantel as egg reduction rates (ERRs), using different frameworks to estimate ERRs among population strata, as average responses, and within strata, as individual responses. We compare our model-based average ERRs to corresponding model-free estimates, using as reference the World Health Organization (WHO) 90 % threshold of optimal efficacy. We estimate distributions of individual responses and summarize the variation among these responses as the fraction of ERRs falling below the WHO threshold.; Generic models for evaluating responses to anthelminthics deepen our understanding of variation among populations, sub-populations and individuals. We discuss the future application of statistical modelling approaches for monitoring and evaluation of PCT programmes targeting human helminthiases in the context of the WHO 2020 control and elimination goals

Occupation of racial grief, loss as a resource : learning from ‘The Combahee River Collective Black Feminist Statement'

The methodology of ‘occupation’ through rereading The Combahee River Collective Black Feminist Statement (The Combahee River Collective, in: James, Sharpley-Whiting (eds) The Black Feminist Reader. Blackwell Publishers Ltd., Oxford, pp 261–270, 1977) demonstrates the necessity of temporal linkages to historical Black feminist texts and the wisdom of Black feminist situated knowers. This paper argues that racism produces grief and loss and as long as there is racism, we all remain in racial grief and loss. However, in stark contrast to the configuration of racial grief and loss as something to get over, perhaps grief and loss can be thought about differently, for example, in terms of racial grief and loss as a resource. This paper questions Western Eurocentric paternalistic responses to Black women’s ‘talk about their feelings of craziness… [under] patriarchal rule’ (The Combahee River Collective 1977: 262) and suggests alternative ways of thinking about the psychological impact of grief and loss in the context of racism. In this paper, a Black feminist occupation of racial grief and loss includes the act of residing within, and the act of working with the constituent elements of racial grief and loss. The proposal is that an occupation of racial grief and loss is a paradoxical catalyst for building a twenty-first century global intersectional Black feminist movement

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Efficacy of oxamniquine and praziquantel in school children from two Schistosoma mansoni endemic areas

Objective: To determine the relative susceptibility of Schistosoma mansoni infections to treatment with the oxamniquine (OXA) and praziquantel (PZQ). Design and setting: Three separate cross sectional studies were performed in six primary schools located in two Schistosoma mansoni endemic areas in Eastern Kenya: Kangundo (low morbidity) and Kibwezi (high morbidity). Subjects: One thousand two hundred and fourteen infected children aged 6-20 years were involved. Intervention: Each child received either 15-mg OXA/kg body weight twice within an interval of six hours or a single dose of 40 or 60 mg PZQ/kg body weight. Three duplicate Kato stool examinations were done before and four or five weeks after treatment to assess treatment efficacy. Results: The cure rates in different schools with OXA were 71.7 - 79.7% in Kangundo and 56.7 - 61.9% in Kibwezi. In children treated with PZQ, the 40-mg/kg-dose regimen achieved cure rates of 77.6 87.2% in Kangundo and 67.1 - 81.1% in Kibwezi, whereas the 60-mg/ kg dose regimen attained cure rates of 93.2% in Kangundo and 76.3% in Kibwezi. Both OXA and PZQ efficacy declined significantly with age in Kangundo, whereas the age effect was not seen in Kibwezi. Conclusion: The poorer cure rates in Kibwezi than in the Kangundo children were not due to known previous drug exposure to either OXA or PZQ. The varying efficacy may be attributed to innate low drug susceptibility, possibly related to schistosom strain differences between the two areas. (East African Medical Journal: 2002 79(1): 29-33

Two sugar isomers influence host plant acceptance by a cereal caterpillar pest

Plant sugars are often considered as primary feeding stimuli, conditioning host plant acceptance by herbivorous insects. Of the nine sugars identified from methanolic extracts of seven grass species, only turanose, a sucrose isomer, was negatively correlated with the survival and growth of the noctuid larva of cereal stemborer, Busseola fusca. Sucrose was the most abundant sugar, although it did not vary significantly in concentration among the plant species studied. Using Styrofoam (TM) cylinders impregnated with increasing concentrations of turanose or sucrose, the two sugars had opposing effects: turanose appeared phagodeterrent while sucrose was phagostimulatory. Electrophysiological studies indicated that B. fusca larvae were able to detect both sugars via their styloconic sensilla located on the mouthparts. The findings indicate that, whereas sucrose is a feeding stimulant and positively influences food choice by B. fusca larvae, turanose negatively contributes to larval food choice. The balance in concentrations of both sugars, however, somehow influences the overall host plant choice made by the larvae. This can partly explain host plant suitability and choice by this caterpillar pest in the field

Spatial patterns of human water contact and Schistosoma mansoni transmission and infection in four rural areas in Machakos District, Kenya

This paper presents the results of microgeographical studies of human water contact behavior and Schistosoma mansoni transmission levels and intensity of infection in four rural areas in Machakos District, Kenya. The relationship between intensity of infection (geometric mean egg counts) in 3502 persons aggregated in 120 household clusters and eight independent variables was investigated using straight and stepwise linear regression and mapping techniques. Results indicate that the two water contact variables, mean frequency per person and mean duration per person, as well as mean number of sites used per person, a transmission index and mean distance to the most frequently used site were the strongest predictors of geometric mean egg counts. All three distance variables were usually negatively associated with infection although intensity of infection and water contact declined relatively slowly with distance from the streams. This pattern appears to be owing to a combination of the relatively short distances, a general lack of safe alternative water sources and the use of more distant water contact sites both inside and outside the study area during periods of drought. The study of snail-to-man transmission identified number of infected snails as the major transmission variable and number of contacts as the major predictor variable. Mapping of total egg counts at the household cluster level and total number of infected snails revealed spatial association with transmission sites. All results varied considerably between study areas, owing to differences in exposure levels, transmission patterns and environmental factors. Findings are discussed in relation to the epidemiology and control of schistosomiasis and suggestions are made for further spatial studies.schistosomiasis water contact behavior transmission dynamics spatial patterns Kenya