Human schistosomiasis in Nigeria: present status, diagnosis, chemotherapy, and herbal medicines

Schistosomiasis is a neglected tropical disease caused by a parasitic, trematode blood fluke of the genus Schistosoma. With 20 million people infected, mostly due to Schistosoma haematobium, Nigeria has the highest burden of schistosomiasis in the world. We review the status of human schistosomiasis in Nigeria regarding its distribution, prevalence, diagnosis, prevention, orthodox and traditional treatments, as well as snail control strategies. Of the country's 36 states, the highest disease prevalence is found in Lagos State, but at a geo-political zonal level, the northwest is the most endemic. The predominantly used diagnostic techniques are based on microscopy. Other methods such as antibody-based serological assays and DNA detection methods are rarely employed. Possible biomarkers of disease have been identified in fecal and blood samples from patients. With respect to preventive chemotherapy, mass drug administration with praziquantel as well as individual studies with artemisinin or albendazole have been reported in 11 out of the 36 states with cure rates between 51.1 and 100%. Also, Nigerian medicinal plants have been traditionally used as anti-schistosomal agents or molluscicides, of which Tetrapleura tetraptera (Oshosho, aridan, Aidan fruit), Carica papaya (Gwanda, Ìbẹ́pẹ, Pawpaw), Borreria verticillata (Karya garma, Irawo-ile, African borreria), and Calliandra portoricensis (Tude, Oga, corpse awakener) are most common in the scientific literature. We conclude that the high endemicity of the disease in Nigeria is associated with the limited application of various diagnostic tools and preventive chemotherapy efforts as well as poor knowledge, attitudes, and practices (KAP). Nonetheless, the country could serve as a scientific base in the discovery of biomarkers, as well as novel plant-derived schistosomicides and molluscicides.

Presentation pattern and survival rate of retinoblastoma following chemotherapy: a prospective study

BACKGROUND

This study presents the clinical pattern of presentation and survival rate of retinoblastoma, which is the most prevalent form of pediatric intraocular cancer. The aim of this study is to provide baseline information about the clinical presentation and management of retinoblastoma at ECWA Eye Hospital. Additionally, the study identifies priority areas for enhancing medical care for children diagnosed with this cancer. ECWA Eye Hospital, situated in Kano State, Nigeria, is a specialized eye center located in the North-Western region of the country.

METHODS

A prospective study spanning five years was conducted at ECWA Eye Hospital to investigate clinically diagnosed cases of retinoblastoma. The study took place from January 2018 to December 2022. The patients received standardized pre-medication and chemotherapy protocols for retinoblastoma. Subsequently, a five-year follow-up was conducted to monitor the patients' progress. The collected data was analyzed, descriptive statistics were generated, and the survival rate was calculated.

RESULTS

During the five-year study period, a total of 35 cases of retinoblastoma were diagnosed. The patients had an average age of 3.21 ± 1.32 years. The most common presentation patterns observed were fungating ocular mass and proptosis. Among the cases, there were 10 instances of bilateral proptosis and 25 instances of unilateral proptosis. While no patients exhibited bilateral leukocoria, eight cases of unilateral leukocoria with anterior segment seedlings were identified. The additional patterns of presentation are proptosis, leukocoria, fungating orbital mass, redness and loss of vision. The mortality rate was 80% (28 cases), while the survival rate was 20% (7 cases). Notably, all the survivors had unilateral retinoblastoma.

CONCLUSION

The majority of cases observed at ECWA Eye Hospital involve advanced retinoblastoma. In low-resource settings where alternative treatment options are limited, chemotherapy is considered a viable treatment option. Early presentation of retinoblastoma in patients may lead to a higher survival rate when chemotherapy is administered.

Molecular detection of Sodalis glossinidius, Spiroplasma species and Wolbachia endosymbionts in wild population of tsetse flies collected in Cameroon, Chad and Nigeria

BACKGROUND

Tsetse flies are cyclical vectors of African trypanosomiasis (AT). The flies have established symbiotic associations with different bacteria that influence certain aspects of their physiology. Vector competence of tsetse flies for different trypanosome species is highly variable and is suggested to be affected by bacterial endosymbionts amongst other factors. Symbiotic interactions may provide an avenue for AT control. The current study provided prevalence of three tsetse symbionts in Glossina species from Cameroon, Chad and Nigeria.

RESULTS

Tsetse flies were collected and dissected from five different locations. DNA was extracted and polymerase chain reaction used to detect presence of Sodalis glossinidius, Spiroplasma species and Wolbachia endosymbionts, using species specific primers. A total of 848 tsetse samples were analysed: Glossina morsitans submorsitans (47.52%), Glossina palpalis palpalis (37.26%), Glossina fuscipes fuscipes (9.08%) and Glossina tachinoides (6.13%). Only 95 (11.20%) were infected with at least one of the three symbionts. Among infected flies, six (6.31%) had Wolbachia and Spiroplasma mixed infection. The overall symbiont prevalence was 0.88, 3.66 and 11.00% respectively, for Sodalis glossinidius, Spiroplasma species and Wolbachia endosymbionts. Prevalence varied between countries and tsetse fly species. Neither Spiroplasma species nor S. glossinidius were detected in samples from Cameroon and Nigeria respectively.

CONCLUSION

The present study revealed, for the first time, presence of Spiroplasma species infections in tsetse fly populations in Chad and Nigeria. These findings provide useful information on repertoire of bacterial flora of tsetse flies and incite more investigations to understand their implication in the vector competence of tsetse flies.

Prooxidant effects of high dose ascorbic acid administration on biochemical, haematological and histological changes in Cavia porcellus (Guinea pigs): a Guinea pig experimental model

Introduction

Ascorbic acid (AA) is a water-soluble vitamin that is well known for its antioxidant and immune-boosting properties. Owing to the wide-range application of AA in the treatment of numerous ailments and its sweet taste, it is usually abused i.e. overused. However, the effect of the abuse has rarely received attention. Therefore, this study was designed to assess the effect of oral administration of high-dose ascorbic acid on biochemical and haematological parameters as well as the effects on the kidney, liver and lungs.

Methods

adult guinea pigs were divided into four (4) groups where group 1 served as the untreated control group and groups 2-4 were dosed with 29 mg, 662 mg and 1258 mg of ascorbic acid per day, respectively for 28 days.

Results

the result revealed that administration of high dose ascorbic acid significantly (P<0.05) increased serum creatinine from 50.0 ± 7.09 (NC) to AA29- 73.8 ± 4.5, AA-662-89.7 ± 3.3 and AA1258- 79.9 ± 5.7mmol/L and urea levels in the treatment group AA-1258 -18.3 ± 0.5 µmol/L compared to the normal group (NC-2.15 ± 0.6 µmol/L). Disturbance in electrolyte balance was observed with a significant (P<0.05) increase in Na+ from NC- 131.3 ± 3.5 mmol/L to 135.7 ± 3.6 mmol/L in the AA-1258 treatment group, Cl- ( NC- 67.1 ± 1.6 mmol/L increased to AA29- 92.1 ± 0.83, AA662- 95.3 ± 1.3 and AA-1258- 95.6 ± 0.4 mmol/L), and Ca2+ (NC- 2.66 ± 0.03 to AA1258- 3.36 ± 0.03 mmol/L) and a significant (P<0.05) decrease in serum K+ in the AA29-5.0 ± 0.2, AA662-5.2 ± 0.3 and AA1258-5.6 ± 0.3 mmol/L treatment groups compared to the normal group 6.6 ± 0.3 mmol/L. There was also a significant (P<0.05) increase in the differential blood count in the animals with a significant (P<0.05) increase in red blood count ( NC-5.11 ± 0.13 ×106/µL to AA1258- 5.75 ± 0.11×106/µL ), haematocrit count (NC 39.90 ± 0.52% to AA-29-42.08 ± 0.24 and AA1258-46.13 ± 0.86%), white blood count (NC 10.15 ± 1.01 ×103/µL to AA1258- 15.18 ± 1.65×103/µL ), total lymphocytes (NC 3.5 ± 0.51×103/µL to AA29-5.28 ±0.43×103/µL), monocytes (NC 0.45 ± 0.07×103/µL to AA1258 0.80 ± 0.07×103/µL), eosinophils (NC 0.23 ± 0.03×103/µL to AA12580.40 ± 0.03×103/µL), basophils (NC0.68 ± 0.10×103/µL to AA12581.20 ± 0.10×103/µL) and neutrophil count (NC 4.73 ± 0.68×103/µL to AA1258 8.36 ± 0.71×103/µL). The histopathological indices indicate cellular necrosis in the AA662 and AA1258 treatment groups of the kidney and liver respectively compared to the normal control which has normal cells.

Conclusion

high dose of ascorbic acid can therefore be suggested to cause damage to the cells by causing cellular necrosis as observed in the histopathology results and has effect on the blood cells as observed in the increase compared to the normal control, and the consequences are possibly triggered through inflammatory responses.

Glycerol biosynthetic pathway plays an essential role in proliferation and antioxidative defense in the human enteric protozoan parasite Entamoeba histolytica

Amebiasis is caused by the protozoan parasite Entamoeba histolytica. Treatment options other than metronidazole and its derivatives are few, and their low efficacy against asymptomatic cyst carriers, and experimental evidence of resistance in vitro justify the discovery/repurposing campaign for new drugs against amebiasis. Global metabolic responses to oxidative stress and cysteine deprivation by E. histolytica revealed glycerol metabolism may represent a rational target for drug development. In this study using 14C-labelled glucose, only 11% of the total glucose taken up by E. histolytica trophozoites is incorporated to lipids. To better understand the role of glycerol metabolism in this parasite, we focused on characterizing two important enzymes, glycerol kinase (GK) and glycerol 3-phosphate dehydrogenase (G3PDH). Recombinant GK was biochemically characterized in detail, while G3PDH was not due to failure of protein expression and purification. GK revealed novel characteristics and unprecedented kinetic properties in reverse reaction. Gene silencing revealed that GK is essential for optimum growth, whereas G3PDH is not. Gene silencing of G3PDH caused upregulated GK expression, while that of GK resulted in upregulation of antioxidant enzymes as shown by RNA-seq analysis. Although the precise molecular link between GK and the upregulation of antioxidant enzymes was not demonstrated, the observed increase in antioxidant enzyme expression upon GK gene silencing suggests a potential connection between GK and the cellular response to oxidative stress. Together, these results provide the first direct evidence of the biological importance and coordinated regulation of the glycerol metabolic pathways for proliferation and antioxidative defense in E. histolytica, justifying the exploitation of these enzymes as future drug targets.

Molecular identification of phlebotomine sand flies and the harbored Leishmania spp. in Sokoto State, Nigeria

Introduction

Female sand flies are hematophagous, feeding on animals and in the process serve as vectors for Leishmania, the parasites that cause leishmaniasis in humans. Leishmaniasis are a group of parasitic neglected tropical diseases in 98 countries including Nigeria and kills ~60,000 people/year. In Nigeria, Sokoto State is endemic to leishmaniasis but there is a knowledge gap on the identity of the prevalent sand flies and the Leishmania species they transmit. Hence, this cross-sectional study was designed to take inventory of the species of sand flies in Sokoto using genetic methods.

Methods

1,260 (310 females) sand flies were collected from three Local Government Areas (L.G.A) of Sokoto State- Wamakko, Sokoto South and Kware. Genomic DNA was extracted from each fly and DNA amplification by polymerase chain reaction (PCR) was carried out on the DNA samples using primers targeting the arthropods mitochondrial cytochrome oxidase subunit 1 (mt-coI) gene, and nested PCR with primers targeting the gene for Leishmania internal transcribed spacer-1 (its-1) of ribosomal RNA its-1rRNA. The PCR products were sequenced.

Results

Gene sequence analysis revealed five species of sand flies belonging to the old-world genera namely Phlebotomus and Sergentomyia. The identified species were P. papatasi (6.45%), S. adleri (6.45%), S. affinis (9.7%), S. distincta (9.7%), S. schwetzi (67.7%). Within the sampling period, sand flies were most abundant in the rainy months of August (104/33.5%) and September (116/37.4%) with all the five identified species occurring. Sequence analysis of its-1 gene identified Leishmania infantum in two sand flies (2/310)- P. papatasi (from Sokoto South) and S. affinis (from Wamakko). BLAST search in NCBI and phylogenetic analysis revealed that the sand fly species are related to the species reported in different parts of Africa, while the L. infantum is identical to strain reported in Brazil (KY379083.1).

Discussion

Phlebotomus papatasi and four species belonging to the genus Sergentomyia are the most prevalent sand flies in Sokoto State, Nigeria and they harbor L. infantum solely. The results shed light on why visceral leishmaniasis is the most predominant form of the disease. Therefore, we recommend that adequate care for dogs must be instituted as dogs are the major animal reservoir for L. infantum.

Targeted protein degradation might present a novel therapeutic approach in the fight against African trypanosomiasis

African trypanosomiasis (AT) is a hemoparasitic disease caused by infection with African trypanosomes and it is prevalent in many sub-Saharan African countries, affecting both humans and domestic animals. The disease is transmitted mostly by haematophagous insects of the genus Glossina while taking blood meal, in the process spreading the parasites from an infected animal to an uninfected animal. The disease is fatal if untreated, and the available drugs are generally ineffective and resulting in toxicities. Therefore, it is still pertinent to explore novel methods and targets for drug discovery. Proteolysis-targeting chimeras (PROTACs) present a new strategy for development of therapeutic molecules that mimic cellular proteasomal-mediated protein degradation to target proteins involved in different disease types. PROTACs have been used to degrade proteins involved in various cancers, neurodegenerative diseases, and immune disorders with remarkable success. Here, we highlight the problems associated with the current treatments for AT, discuss the concept of PROTACs and associated targeted protein degradation (TPD) approaches, and provide some insights on the future potential for the use of these emerging technologies (PROTACs and TPD) for the development of new generation of anti-Trypanosoma drugs and the first "TrypPROTACs".

Molecular detection of Sodalis glossinidius, Spiroplasma and Wolbachia endosymbionts in wild population of tsetse flies collected in Cameroon, Chad and Nigeria

Background Tsetse flies are cyclical vectors of African trypanosomiasis. They have established symbiotic associations with different bacteria, which influence certain aspects of their physiology. The vector competence of tsetse flies for different trypanosome species is highly variable and is suggested to be affected by various factors, amongst which are bacterial endosymbionts. Symbiotic interactions may provide an avenue for the disease control. The current study provided the prevalence of 3 tsetse symbionts in Glossina species from Cameroon, Chad and Nigeria. Results Tsetse flies were collected from five different locations and dissected. DNA was extracted and polymerase chain reaction PCR was used to detect the presence of Sodalis glossinidius , Spiroplasma sp and Wolbachia using specific primers. A total of 848 tsetse samples were analysed: Glossina morsitans submorsitans (47.52%), Glossina palpalis palpalis (37.26%), Glossina fuscipes fuscipes (9.08%) and Glossina tachinoides (6.13%). Only 95 (11.20%) were infected with at least one of the 3 symbionts. Among the infected, 6 (6.31%) were carrying mixed infection ( Wolbachia and Spiroplasma ). The overall symbiont prevalence was 0.88%, 3.66% and 11.00% respectively, for Sodalis , Spiroplasma and Wolbachia . Prevalence varied between countries and tsetse species. No Spiroplasma was detected in samples from Cameroon and no Sodalis was found in samples from Nigeria. Conclusion The present study revealed for the first time, the presence of infection by Spiroplasma in tsetse in Chad and Nigeria. These findings provide useful information to the repertoire of bacterial flora of tsetse flies and incite to more investigations to understand their implication in the vector competence of tsetse flies.

A 5-year retrospective study of intraocular pressure control after trabeculectomy: a retrospective cohort study

Glaucoma is a group of diseases that damage the optic nerve in the eye, resulting in vision loss and, in severe cases, blindness. The prevalence of glaucoma and glaucoma blindness is highest in West Africans.

Objective

The study presents a 5-year retrospective analysis of intraocular pressure (IOP) and complications after trabeculectomy.

Materials and methods

Trabeculectomy was performed using 5 mg/ml of 5-fluorouracil. A gentle diathermy was performed to secure hemostasis. Using a blade fragment of the scleral thickness, a 4×3 mm rectangular scleral flap was dissected. The central part of the flap was dissected 1 mm into the clear cornea. Before being tailed down, the patient was given topical 0.05% dexamethasone qid, 1% atropine tid, and 0.3% ciprofloxacin qid for 4-6 weeks. Patients with pain were given pain relievers, and all patients with photophobia were given sun protection. A successful surgical outcome was defined as a postoperative IOP of 20 mmHg or less.

Results

There were 161 patients over the 5-year period under review, with men constituting 70.2% of the total. Out of 275 eyes operated on, 82.9% were bilateral cases, while 17.1% were unilateral. Glaucoma was found in both children and adults aged 11-82 years. However, it was observed to predominate between the ages of 51 and 60, with males having the highest incidence. The average preoperative IOP was 24.37 mmHg, while it was 15.24 mmHg postoperatively. The complication with the highest ranking was shallow anterior chamber (24; 8.73%) due to overfiltration, followed by leaking bleb (8; 2.91%). The most common late complications were cataract (32; 11.64%) and fibrotic bleb (8; 2.91%). Bilateral cataracts developed at an average of 25 months after trabeculectomy. It was seen in patients aged 2-3 with a frequency of 9, whereas 5 years after, 77 patients had improved vision, with a postoperative visual acuity of 6/18-6/6.

Conclusion

Postoperatively, the patients had satisfying surgical outcomes as a result of the decrease in preoperative IOP. Although postoperative complications occurred, they had no effect on the surgical outcomes because they were temporary and not optically threatening. In our experience, trabeculectomy is an effective and safe procedure for achieving IOP control.

Identification of megacerotonic acid and a quinazoline derivative from Universal Natural Product Database as potential inhibitors of Trypanosoma brucei brucei alternative oxidase: molecular docking, molecular dynamic simulation and MM/PBSA analysis

African trypanosomiasis is caused by Trypanosoma brucei subspecies and available drugs against it, are unsatisfactory due to poor pharmacokinetic properties. Trypanosomal Alternative Oxidase (TAO) is an attractive target for anti-trypanosome rational drug discovery because it is essential for parasite-specific ATP generation and absent in the mammalian host. In this study, 360 filtered ligands from the Universal Natural Product Database were virtually screened and docked on T. brucei brucei TAO (PDB-ID 3VVA). From the virtual screening, 10 ligands with binding energy from -10.6 to -9.0 kcal/mol were selected as hits and further subjected pharmacokinetic and toxicity analyses where all of them passed Lipinski's rule of five. Also, the compounds were non-mutagenic, non-tumorigenic and could cross the blood brain barrier. The two topmost hits (UNPD29179; megacerotonic acid and UNPD41551; a quinazoline derivative) interacted with `four glutamates (Glu123, Glu162, Glu213 and Glu266) close to di-iron (2 iron elements) at the catalytic site of the enzyme. Subsequently, 100 ns MD simulations of the two topmost hits were performed using GROMACS where high RMSD values of 0.75 nm (TAO-UNPD29179) and 0.52 nm (TAO- UNPD41551), low residues fluctuations and consistent values of radius of gyration were observed. Moreover, Solvent Accessible Surface Area showed a consistent value of 160 nm2 for both complexes while TAO-UNPD29179 had higher number of hydrogen bonds than the TAO-UNPD41551. Similarly, MM/PBSA calculations indicated that UNPD29179 had higher free binding energy with TAO than UNPD41551. The data suggest that megacerotonic acid and a quinazoline derivative could be potential inhibitors of TAO with improved pharmacokinetic properties.Communicated by Ramaswamy H. Sarma.

Microsecond-long simulation reveals the molecular mechanism for the dual inhibition of falcipain-2 and falcipain-3 by antimalarial lead compounds

The latest world malaria report revealed that human deaths caused by malaria are currently on the rise and presently stood at over 627,000 per year. In addition, more than 240 million people have the infection at any given time. These figures make malaria the topmost infectious disease and reiterate the need for continuous efforts for the development of novel chemotherapies. Malaria is an infectious disease caused majorly by the protozoan intracellular parasite Plasmodium falciparum and transmitted by mosquitoes. Reports abound on the central role of falcipains (cysteine protease enzymes) in the catabolism of hemoglobin for furnishing the plasmodium cells with amino acids that they require for development and survival in the hosts. Even though falcipains (FPs) have been validated as drug target molecules for the development of new antimalarial drugs, none of its inhibitory compounds have advanced beyond the early discovery stage. Therefore, there are renewed efforts to expand the collection of falcipain inhibitors. As a result, an interesting finding reported the discovery of a quinolinyl oxamide derivative (QOD) and an indole carboxamide derivative (ICD), with each compound demonstrating good potencies against the two essential FP subtypes 2 (FP-2) and 3 (FP-3). In this study, we utilized microsecond-scale molecular dynamics simulation computational method to investigate the interactions between FP-2 and FP-3 with the quinolinyl oxamide derivative and indole carboxamide derivative. The results revealed that quinolinyl oxamide derivative and indole carboxamide derivative bound tightly at the active site of both enzymes. Interestingly, despite belonging to different chemical scaffolds, they are coordinated by almost identical amino acid residues via extensive hydrogen bond interactions in both FP-2 and FP-3. Our report provided molecular insights into the interactions between FP-2 and FP-3 with quinolinyl oxamide derivative and indole carboxamide derivative, which we hope will pave the way towards the design of more potent and druglike inhibitors of these enzymes and will pave the way for their development to new antimalarial drugs.

Genetic Diversity of Microcystin Producers (Cyanobacteria) and Microcystin Congeners in Aquatic Resources across Africa: A Review Paper

Microcystins are produced by multifaceted organisms called cyanobacteria, which are integral to Africa's freshwater environments. The excessive proliferation of cyanobacteria caused by rising temperature and eutrophication leads to the production and release of copious amounts of microcystins, requiring critical management and control approaches to prevent the adverse environmental and public health problems associated with these bioactive metabolites. Despite hypotheses reported to explain the phylogeography and mechanisms responsible for cyanobacterial blooms in aquatic water bodies, many aspects are scarcely understood in Africa due to the paucity of investigations and lack of uniformity of experimental methods. Due to a lack of information and large-scale studies, cyanobacteria occurrence and genetic diversity are seldom reported in African aquatic ecosystems. This review covers the diversity and geographical distribution of potential microcystin-producing and non-microcystin-producing cyanobacterial taxa in Africa. Molecular analyses using housekeeping genes (e.g., 16S rRNA, ITS, rpoC1, etc.) revealed significant sequence divergence across several cyanobacterial strains from East, North, West, and South Africa, but the lack of uniformity in molecular markers employed made continent-wise phylogenetic comparisons impossible. Planktothrix agardhii, Microcystis aeruginosa, and Cylindrospermopsis raciborskii (presently known as Raphidiopsis raciborskii) were the most commonly reported genera. Potential microcystin (MCs)-producing cyanobacteria were detected using mcy genes, and several microcystin congeners were recorded. Studying cyanobacteria species from the African continent is urgent to effectively safeguard public and environmental health because more than 80% of the continent has no data on these important microorganisms and their bioactive secondary metabolites.

Immunoinformatic design of a putative multi-epitope vaccine candidate against Trypanosoma brucei gambiense

Human African trypanosomiasis (HAT) is a neglected tropical disease that is caused by flagellated parasites of the genus Trypanosoma. HAT imposes a significant socio-economic burden on many countries in sub-Saharan Africa and its control is hampered by several drawbacks ranging from the ineffectiveness of drugs, complex dosing regimens, drug resistance, and lack of a vaccine. Despite more than a century of research and investigations, the development of a vaccine to tackle HAT is still challenging due to the complex biology of the pathogens. Advancements in computational modeling coupled with the availability of an unprecedented amount of omics data from different organisms have allowed the design of new generation vaccines that offer better antigenicity and safety profile. One of such new generation approaches is a multi-epitope vaccine (MEV) designed from a collection of antigenic peptides. A MEV can stimulate both cellular and humoral immune responses as well as avoiding possible allergenic reactions. Herein, we take advantage of this approach to design a MEV from conserved hypothetical plasma membrane proteins of Trypanosoma brucei gambiense, the trypanosome subspecies that is responsible for the west and central African forms of HAT. The designed MEV is 402 amino acids long (41.5 kDa). It is predicted to be antigenic, non-toxic, to assume a stable 3D conformation, and to interact with a key immune receptor. In addition, immune simulation foresaw adequate immune stimulation by the putative antigen and a lasting memory. Therefore, the designed chimeric vaccine represents a potential candidate that could be used to target HAT.

Epizootiology and Molecular Identification of Trypanosome Species in Livestock Ruminants in the Gambia

INTRODUCTION

African Animal Trypanosomiasis (AAT) or nagana in animals, is caused by the blood-borne parasitic protozoa called trypanosomes, and is potentially fatal. It is estimated that Africa loses $4‒5 billion annually due to the death of livestock to nagana in the tsetse belt.

PURPOSE

Although The Gambia lies within this belt, there is scanty data regarding the epizootiology of nagana in The Gambia. Here, records of reported cases of nagana for the period 2010-2019 at the International Trypanotolerance Centre (ITC) in The Gambia were analyzed retrospectively.

METHODS

For insights into the current prevalence of AAT, blood samples of 384 cattle, 42 goats, and 59 sheep from the Central River Region (CRR) and Lower River Region (LRR) were analyzed microscopically for parasite identification. Furthermore, trypanosomes were characterized by polymerase chain reaction (PCR) using a panel of primers that identify trypanosomes to the level of the species and subspecies by targeting a portion of the internally transcribed spacer-one (ITS-1) of the ribosomal RNA.

RESULTS

The retrospective study indicates that Trypanosoma vivax (66%) and T. congolense (33.4%) were the predominant species. Based on the archive records of ITC, the villages Touba, Misera, and Sambel Kunda all in the CRR of the Gambia are the most burdened with AAT. Microscopic examination of blood samples from cattle showed a prevalence of 1.56%, whereas the PCR-based analysis gave a higher prevalence of 12.5%. The molecular analysis revealed the presence of T. vivax (3.65%), T. congolense kilifi (2.6%), T. b. brucei (1.3%), T. congolense savannah/forest (0.52%), T. b. gambiense (0.52%). Interestingly, 4.43% of mixed infections i.e. multiple trypanosome species in individual animals were recorded. In 18% of the mixed infection cases, T. godfreyi, T. simiae were coinfecting cattle alongside T. congolense. The molecular identification including the phylogenetic analysis implicated T. congolense as the most predominant trypanosome species infecting animals in The Gambia.

CONCLUSION

The incidence of nagana in The Gambia is documented and the prevalent trypanosomes identified to be T. vivax, different types of T. congolense, and T. brucei including the gambiense subspecie. Finally, nagana is less profound in sheep and goats compared to cattle, with seasonal and regional variations playing a significant role in the disease dynamics.

Awareness and preparedness of healthcare workers against the first wave of the COVID-19 pandemic: A cross-sectional survey across 57 countries

BACKGROUND

Since the COVID-19 pandemic began, there have been concerns related to the preparedness of healthcare workers (HCWs). This study aimed to describe the level of awareness and preparedness of hospital HCWs at the time of the first wave.

METHODS

This multinational, multicenter, cross-sectional survey was conducted among hospital HCWs from February to May 2020. We used a hierarchical logistic regression multivariate analysis to adjust the influence of variables based on awareness and preparedness. We then used association rule mining to identify relationships between HCW confidence in handling suspected COVID-19 patients and prior COVID-19 case-management training.

RESULTS

We surveyed 24,653 HCWs from 371 hospitals across 57 countries and received 17,302 responses from 70.2% HCWs overall. The median COVID-19 preparedness score was 11.0 (interquartile range [IQR] = 6.0-14.0) and the median awareness score was 29.6 (IQR = 26.6-32.6). HCWs at COVID-19 designated facilities with previous outbreak experience, or HCWs who were trained for dealing with the SARS-CoV-2 outbreak, had significantly higher levels of preparedness and awareness (p<0.001). Association rule mining suggests that nurses and doctors who had a 'great-extent-of-confidence' in handling suspected COVID-19 patients had participated in COVID-19 training courses. Male participants (mean difference = 0.34; 95% CI = 0.22, 0.46; p<0.001) and nurses (mean difference = 0.67; 95% CI = 0.53, 0.81; p<0.001) had higher preparedness scores compared to women participants and doctors.

INTERPRETATION

There was an unsurprising high level of awareness and preparedness among HCWs who participated in COVID-19 training courses. However, disparity existed along the lines of gender and type of HCW. It is unknown whether the difference in COVID-19 preparedness that we detected early in the pandemic may have translated into disproportionate SARS-CoV-2 burden of disease by gender or HCW type.

Risk factors for Rift Valley fever virus seropositivity in one-humped camels (Camelus dromedarius) and pastoralist knowledge and practices in Northern Nigeria

Rift Valley fever (RVF) is a complex emerging arboviral hemorrhagic disease that causes significant illness in animals and humans. Camel trade across the land borders between Nigeria and the Niger Republic occurs frequently and poses a significant risk for RVF transmission to pastoralists and traders. We carried a cross-sectional study between November 2016 and April 2017 in two northern States (Katsina and Jigawa) known for camel trade in Nigeria to investigate the seroprevalence and potential risk factors for RVFV occurrence. We collected 720 sera and administered questionnaire to pastoralists. We used the competitive enzyme-linked immunosorbent assay (c-ELISA) to determine the previous exposure to RVFV infection. We retrieved  environmental information from public data sources that might explain RVFV seropositivity at  the LGA level. To asses potential risk factors,we categorized LGAs with RVFV as "1" and those without a case" 0". We fitted a logistic model to the data  and estimated odds ratios and 95% confidence intervals. An overall 19.9% prevalence was reported among camel herd-the highest seropositivity (33.3%) was recorded in SuleTankarkar LGA. In the multivariable model, only rain-fed croplands was significantly associated with RVFV antibodies occurrence p = 0.048 (OR = 0.87, 95% CI: 0.76-0.99). Only a minority of the respondents, 19.3% (n = 17/88), knew that RVF is zoonotic. Separation of healthy animals from the infected animals was carried out by 53.4% (47/88) pastoralists while 59.1% (52/88) pastoralists still use ethnoveterinary practices to control or mitigate disease outbreaks. Our study demonstrates the presence of RVFV antibodies among camel in Nigeria and the associated risk factors. These findings highlight the need for enhancing surveillance and control efforts and the public health education of camel pastoralists. Further investigation to unravel the zoonotic transmission potential to pastoralists and other animal species is pertinent.

The integration of artificial intelligence in medical imaging practice: Perspectives of African radiographers

INTRODUCTION

The current technological developments in medical imaging are centred largely on the increasing integration of artificial intelligence (AI) into all equipment modalities. This survey assessed the perspectives of African radiographers on the integration of AI in medical imaging in order to offer unique recommendations to support the training of the radiography workforce.

METHODS

An exploratory cross-sectional online survey of radiographers working within Africa was conducted from March to August 2020. The survey obtained data about their demographics and perspectives on AI implementation and usage. Data obtained were analysed using both descriptive and inferential statistics.

RESULTS

A total of 1020 valid responses were obtained. Majority of the respondents (n = 883,86.6%) were working in general X-ray departments. Of the respondents, 84.9% (n = 866) indicated that AI technology would improve radiography practice and quality assurance for efficient diagnosis and improved clinical care. Fear of job losses following the implementation of AI was a key concern of most radiographers (n = 625,61.3%).

CONCLUSION

Generally, radiographers were delighted about the integration of AI into medical imaging, however; there were concerns about job security and lack of knowledge. There is an urgent need for stakeholders in medical imaging infrastructure development and practices in Africa to start empowering radiographers through training programmes, funding, motivational support, and create clear roadmaps to guide the adoption and integration of AI in medical imaging in Africa.

IMPLICATION FOR PRACTICE

The current study offers unique suggestions and recommendations to support the training of the African radiography workforce and others in similar resource-limited settings to provide quality care using AI-integrated imaging modalities.

Plasmodium falciparum multidrug resistance gene-1 polymorphisms in Northern Nigeria: implications for the continued use of artemether-lumefantrine in the region

Background

The analysis of single nucleotide polymorphism (SNPs) in drug-resistance associated genes is a commonly used strategy for the surveillance of anti-malarial drug resistance in populations of parasites. The present study was designed and performed to provide genetic epidemiological data of the prevalence of N86Y-Y184F-D1246Y SNPs in Plasmodium falciparum multidrug resistance 1 (pfmdr1) in the malaria hotspot of Northern Nigeria.

Methods

Plasmodium falciparum-positive blood samples on Whatman-3MM filter papers were collected from 750 symptomatic patients from four states (Kano, Kaduna, Yobe and Adamawa) in Northern Nigeria, and genotyped via BigDye (v3.1) terminator cycle sequencing for the presence of three SNPs in pfmdr1. SNPs in pfmdr1 were used to construct NYD, NYY, NFY, NFD, YYY, YYD, YFD and YFY haplotypes, and all data were analysed using Pearson Chi square and Fisher’s exact (FE) tests.

Results

The prevalence of the pfmdr1 86Y allele was highest in Kaduna (12.50%, ² = 10.50, P = 0.02), whilst the 184F allele was highest in Kano (73.10%, ² = 13.20, P = 0.00), and the pfmdr1 1246Y allele was highest in Yobe (5.26%, ² = 9.20, P = 0.03). The NFD haplotype had the highest prevalence of 69.81% in Kano (² = 36.10, P = 0.00), followed by NYD with a prevalence of 49.00% in Adamawa, then YFD with prevalence of 11.46% in Kaduna. The YYY haplotype was not observed in any of the studied states.

Conclusion

The present study suggests that strains of P. falciparum with reduced sensitivity to the lumefantrine component of AL exist in Northern Nigeria and predominate in the North-West region.

Discovery of trypanocidal coumarins with dual inhibition of both the glycerol kinase and alternative oxidase of Trypanosoma brucei brucei

African trypanosomiasis, sleeping sickness in humans or nagana in animals, is a potentially fatal neglected tropical disease and a threat to 65 million human lives and 100 million small and large livestock animals in sub-Saharan Africa. Available treatments for this devastating disease are few and have limited efficacy, prompting the search for new drug candidates. Simultaneous inhibition of the trypanosomal glycerol kinase (TGK) and trypanosomal alternative oxidase (TAO) is considered a validated strategy toward the development of new drugs. Our goal is to develop a TGK-specific inhibitor for coadministration with ascofuranone (AF), the most potent TAO inhibitor. Here, we report on the identification of novel compounds with inhibitory potency against TGK. Importantly, one of these compounds (compound 17) and its derivatives (17a and 17b) killed trypanosomes even in the absence of AF. Inhibition kinetics revealed that derivative 17b is a mixed-type and competitive inhibitor for TGK and TAO, respectively. Structural data revealed the molecular basis of this dual inhibitory action, which, in our opinion, will aid in the successful development of a promising drug to treat trypanosomiasis. Although the EC₅₀ of compound 17b against trypanosome cells was 1.77 µM, it had no effect on cultured human cells, even at 50 µM.-Balogun, E. O., Inaoka, D. K., Shiba, T., Tsuge, C., May, B., Sato, T., Kido, Y., Nara, T., Aoki, T., Honma, T., Tanaka, A., Inoue, M., Matsuoka, S., Michels, P. A. M., Watanabe, Y.-I., Moore, A. L., Harada, S., Kita, K. Discovery of trypanocidal coumarins with dual inhibition of both the glycerol kinase and alternative oxidase of Trypanosoma brucei brucei.

Insights into the ubiquinol/dioxygen binding and proton relay pathways of the alternative oxidase

The alternative oxidase (AOX) is a monotopic diiron carboxylate protein which catalyzes the four-electron reduction of dioxygen to water by ubiquinol. Although we have recently determined the crystal structure of Trypanosoma brucei AOX (TAO) in the presence and absence of ascofuranone (AF) derivatives (which are potent mixed type inhibitors) the mechanism by which ubiquinol and dioxygen binds to TAO remain inconclusive. In this article, ferulenol was identified as the first competitive inhibitor of AOX which has been used to probe the binding of ubiquinol. Surface plasmon resonance reveals that AF is a quasi-irreversible inhibitor of TAO whilst ferulenol binding is completely reversible. The structure of the TAO-ferulenol complex, determined at 2.7 Å, provided insights into ubiquinol binding and has also identified a potential dioxygen molecule bound in a side-on conformation to the diiron center for the first time.

Biochemical studies of membrane bound Plasmodium falciparum mitochondrial L-malate:quinone oxidoreductase, a potential drug target

Plasmodium falciparum is an apicomplexan parasite that causes the most severe malaria in humans. Due to a lack of effective vaccines and emerging of drug resistance parasites, development of drugs with novel mechanisms of action and few side effects are imperative. To this end, ideal drug targets are those essential to parasite viability as well as absent in their mammalian hosts. The mitochondrial electron transport chain (ETC) of P. falciparum is one source of such potential targets because enzymes, such as L-malate:quinone oxidoreductase (PfMQO), in this pathway are absent humans. PfMQO catalyzes the oxidation of L-malate to oxaloacetate and the simultaneous reduction of ubiquinone to ubiquinol. It is a membrane protein, involved in three pathways (ETC, the tricarboxylic acid cycle and the fumarate cycle) and has been shown to be essential for parasite survival, at least, in the intra-erythrocytic asexual stage. These findings indicate that PfMQO would be a valuable drug target for development of antimalarial with novel mechanism of action. Up to this point in time, difficulty in producing active recombinant mitochondrial MQO has hampered biochemical characterization and targeted drug discovery with MQO. Here we report for the first time recombinant PfMQO overexpressed in bacterial membrane and the first biochemical study. Furthermore, about 113 compounds, consisting of ubiquinone binding site inhibitors and antiparasitic agents, were screened resulting in the discovery of ferulenol as a potent PfMQO inhibitor. Finally, ferulenol was shown to inhibit parasite growth and showed strong synergism in combination with atovaquone, a well-described anti-malarial and bc₁ complex inhibitor.

Glycerol kinase of African trypanosomes possesses an intrinsic phosphatase activity

BACKGROUND

In general, glycerol kinases (GKs) are transferases that catalyze phospho group transfer from ATP to glycerol, and the mechanism was suggested to be random bi-bi. The reverse reaction i.e. phospho transfer from glycerol 3-phosphate (G3P) to ADP is only physiologically feasible by the African trypanosome GK. In contrast to other GKs the mechanism of Trypanosoma brucei gambiense glycerol kinase (TbgGK) was shown to be in an ordered fashion, and proceeding via autophosphorylation. From the unique reaction mechanism of TbgGK, we envisaged its potential to possess phosphatase activity in addition to being a kinase.

METHODS

Our hypothesis was tested by spectrophotometric and LC-MS/MS analyses using paranitrophenyl phosphate (pNPP) and TbgGK's natural substrate, G3P respectively. Furthermore, protein X-ray crystallography and site-directed mutagenesis were performed to examine pNPP binding, catalytic residues, and the possible reaction mechanism.

RESULTS

In addition to its widely known and expected phosphotransferase (class II) activity, TbgGK can efficiently facilitate the hydrolytic cleavage of phosphoric anhydride bonds (a class III property). This phosphatase activity followed the classical Michaelis-Menten pattern and was competitively inhibited by ADP and G3P, suggesting a common catalytic site for both activities (phosphatase and kinase). The structure of the TGK-pNPP complex, and structure-guided mutagenesis implicated T276 to be important for the catalysis. Remarkably, we captured a crystallographic molecular snapshot of the phosphorylated T276 reaction intermediate.

CONCLUSION

We conclude that TbgGK has both kinase and phosphatase activities.

GENERAL SIGNIFICANCE

This is the first report on a bifunctional kinase/phosphatase enzyme among members of the sugar kinase family.

Conjugates of 2,4-Dihydroxybenzoate and Salicylhydroxamate and Lipocations Display Potent Antiparasite Effects by Efficiently Targeting the Trypanosoma brucei and Trypanosoma congolense Mitochondrion

We investigated a chemical strategy to boost the trypanocidal activity of 2,4-dihydroxybenzoic acid (2,4-DHBA)- and salicylhydroxamic acid (SHAM)-based trypanocides with triphenylphosphonium and quinolinium lipophilic cations (LC). Three series of LC conjugates were synthesized that were active in the submicromolar (5a-d and 10d-f) to low nanomolar (6a-f) range against wild-type and multidrug resistant strains of African trypanosomes (Trypanosoma brucei brucei and T. congolense). This represented an improvement in trypanocidal potency of at least 200-fold, and up to >10 000-fold, compared with that of non-LC-coupled parent compounds 2,4-DHBA and SHAM. Selectivity over human cells was >500 and reached >23 000 for 6e. Mechanistic studies showed that 6e did not inhibit the cell cycle but affected parasite respiration in a dose-dependent manner. Inhibition of trypanosome alternative oxidase and the mitochondrial membrane potential was also studied for selected compounds. We conclude that effective mitochondrial targeting greatly potentiated the activity of these series of compounds.

Molecular basis for the reverse reaction of African human trypanosomes glycerol kinase

The glycerol kinase (GK) of African human trypanosomes is compartmentalized in their glycosomes. Unlike the host GK, which under physiological conditions catalyzes only the forward reaction (ATP-dependent glycerol phosphorylation), trypanosome GK can additionally catalyze the reverse reaction. In fact, owing to this unique reverse catalysis, GK is potentially essential for the parasites survival in the human host, hence a promising drug target. The mechanism of its reverse catalysis was unknown; therefore, it was not clear if this ability was purely due to its localization in the organelles or whether structure-based catalytic differences also contribute. To investigate this lack of information, the X-ray crystal structure of this protein was determined up to 1.90 Å resolution, in its unligated form and in complex with three natural ligands. These data, in conjunction with results from structure-guided mutagenesis suggests that the trypanosome GK is possibly a transiently autophosphorylating threonine kinase, with the catalytic site formed by non-conserved residues. Our results provide a series of structural peculiarities of this enzyme, and gives unexpected insight into the reverse catalysis mechanism. Together, they provide an encouraging molecular framework for the development of trypanosome GK-specific inhibitors, which may lead to the design of new and safer trypanocidal drug(s).

Anemia amelioration by lactose infusion during trypanosomosis could be associated with erythrocytes membrane de-galactosylation

African trypanosomosis is a potentially fatal disease that is caused by extracellular parasitic protists known as African trypanosomes. These parasites inhabit the blood stream of their mammalian hosts and produce a number of pathological features, amongst which is anemia. Etiology of the anemia has been partly attributed to an autoimmunity-like mediated erythrophagocytosis of de-sialylated red blood cells (dsRBCs) by macrophages. Lactose infusion to infected animals has proven effective at delaying progression of the anemia. However, the mechanism of this anemia prevention is yet to be well characterized. Here, the hypothesis of a likely induced further modification of the dsRBCs was investigated. RBC membrane galactose (RBC m-GAL) and packed cell volume (PCV) were measured during the course of experimental trypanosomosis in mice infected with Trypanosoma congolense (stb 212). Intriguingly, while the membrane galactose on the RBCs of infected and lactose-treated mice (group D) decreased as a function of parasitemia, that of the lactose-untreated infected group (group C) remained relatively constant, as was recorded for the uninfected lactose-treated control (group B) animals. At the peak of infection, the respective cumulative percent decrease in PCV and membrane galactose were 30 and 185 for group D, and 84 and 13 for group C. From this observed inverse relationship between RBCs membrane galactose and PCV, it is logical to rationalize that the delay of anemia progression during trypanosomosis produced by lactose might have resulted from an induction of galactose depletion from dsRBCs, thereby preventing their recognition by the macrophages.

Structure of the trypanosome cyanide-insensitive alternative oxidase

In addition to haem copper oxidases, all higher plants, some algae, yeasts, molds, metazoans, and pathogenic microorganisms such as Trypanosoma brucei contain an additional terminal oxidase, the cyanide-insensitive alternative oxidase (AOX). AOX is a diiron carboxylate protein that catalyzes the four-electron reduction of dioxygen to water by ubiquinol. In T. brucei, a parasite that causes human African sleeping sickness, AOX plays a critical role in the survival of the parasite in its bloodstream form. Because AOX is absent from mammals, this protein represents a unique and promising therapeutic target. Despite its bioenergetic and medical importance, however, structural features of any AOX are yet to be elucidated. Here we report crystal structures of the trypanosomal alternative oxidase in the absence and presence of ascofuranone derivatives. All structures reveal that the oxidase is a homodimer with the nonhaem diiron carboxylate active site buried within a four-helix bundle. Unusually, the active site is ligated solely by four glutamate residues in its oxidized inhibitor-free state; however, inhibitor binding induces the ligation of a histidine residue. A highly conserved Tyr220 is within 4 Å of the active site and is critical for catalytic activity. All structures also reveal that there are two hydrophobic cavities per monomer. Both inhibitors bind to one cavity within 4 Å and 5 Å of the active site and Tyr220, respectively. A second cavity interacts with the inhibitor-binding cavity at the diiron center. We suggest that both cavities bind ubiquinol and along with Tyr220 are required for the catalytic cycle for O2 reduction.

Overproduction, purification, crystallization and preliminary X-ray diffraction analysis of Trypanosoma brucei gambiense glycerol kinase

In the bloodstream forms of human trypanosomes, glycerol kinase (GK; EC 2.7.1.30) is one of the nine glycosomally compartmentalized enzymes that are essential for energy metabolism. In this study, a recombinant Trypanosoma brucei gambiense GK (rTbgGK) with an N-terminal cleavable His(6) tag was overexpressed, purified to homogeneity and crystallized by the sitting-drop vapour-diffusion method using PEG 400 as a precipitant. A complete X-ray diffraction data set to 2.75 A resolution indicated that the crystals belonged to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 63.84, b = 121.50, c = 154.59 A. The presence of two rTbgGK molecules in the asymmetric unit gives a Matthews coefficient (V(M)) of 2.5 A(3) Da(-1), corresponding to 50% solvent content.

Quantitative changes in gastric mucosal glycoproteins: effect of cholinergic agonist and vagal nerve stimulation in the rat

The role of the vagus nerve and cholinergic mechanisms in the control of the rat gastric mucin and protein (PROT) release in vivo was investigated. Under urethane anaesthesia (1.25 g kg(-1)), the rats had their gastric lumen perfused with saline. Mucus secretion was measured as a function of adherent mucus on the mucosa surface and the luminal content of sialic acids (SIA), galactose (GAL), pyruvate and PROT. Electrical stimulation of the vagi significantly increased the levels of mucus (3.23 +/- 025 microg g(-1) tissue, P < 0.05), free sialic acid (FS) (0.18 +/- 0.04 mg mL(-1), P < 0.05) and PROT (0.25 +/- 0.003 mg mL(-1), P < 0.05) when compared with control animals. Bilateral cervical vagotomy had no significant effect on adherent mucus or basal levels of PROT, SIA and GAL (P > 0.05) with respect to the control. In both vagotomized and vagal intact animals, the cholinergic agonist (carbachol, 200 mg kg(-1)) significantly increased PROT, adherent mucus and FS (P < 0.05) and decreased bound sialic acid (P > 0.05). There were no visible haemorrhagic streaks on the gastric mucosa of vagotomized, vagal intact and carbachol-treated animals. The results suggest that vagus nerve does not exert a tonic control on gastric glycoprotein secretion in vivo and that cholinergic effect on the mucus secreting cells may be implemented via the intrinsic nerves of the enteric nervous system.