Co-endemicity of loiasis and onchocerciasis in rain forest communities in southwestern Nigeria

Anti-filarial efficacy of Centratherum anthelminticum: unravelling the underlying mechanisms through biochemical, HRAMS proteomics and MD simulation approaches

Traditionally, Centratherum anthelminticum (CA) has been reported to be a potent anti-filarial, however no reports are available detailing its mechanism of action against filarial parasites. In this study, we have evaluated the anti-filarial activity of CA against lymphatic filarial parasites Setaria cervi using ex vivo biochemical, proteomics and in silico approaches. The motility and viability of the parasites decreased significantly after treatment with CA concentrations of ≥125 μg mL-1. An increase in lipid peroxidation (51.92%), protein carbonylation (48.99%), NADPH oxidase (88.88%) activity and decrease in the glutathione (GSH) (-39.23%), glutathione reductase (GR) (-60.17%), and glutathione S-transferase (GST) (-50.48%) activity was also observed after CA treatment. The proteomics analysis was performed by two-dimensional gel electrophoresis and high-resolution accurate mass spectrometry (HRAMS). In total, 185 proteins were differentially expressed (DEPs) following CA treatment. The major DEPs were mostly involved in tRNA processing, biosynthetic processes, metabolic activities, protein transport, the tricarboxylic acid cycle, protein translation, and stress response. The UPLC-ESI-MS/MS analysis of CA extract revealed the presence of 40 bioactive compounds. Further the docking analysis showed 10 CA bioactive compounds to have high binding affinity towards antioxidant proteins of filarial parasites. Additionally, MD simulation studies showed stable interactions (RMSF ≤ 10 Å) of 3-O-methylquercitin, quinic acid, gentisic acid, and vanillin with filarial antioxidant enzymes/proteins. To our knowledge, this is the first report detailing the molecular mechanism of anti-filarial activity of CA, which can be further evaluated for the development of new anti-filarial formulations.

Sociodemographics, Clinical Factors, and Biological Factors Associated with Loiasis in Endemic Onchocerciasis Areas in Southern Gabon

To implement the appropriate strategies for scale-up interventions to eliminate onchocerciasis without severe adverse events, clinical and biological factors associated with loiasis were analyzed in onchocerciasis-endemic areas. Blood was collected from volunteers after examination by a physician. Detection of microfilariae and measurement of Ov16 IgG4 were performed using direct microscopic examination of blood and onchocerciasis rapid test detection, respectively. Areas with sporadic, hypoendemic, and hyperendemic onchocerciasis endemicity were found. Participants with microfilaremia were considered microfilaremic, and those without microfilaremia were seen as amicrofilaremic. Of the 471 study participants, 40.5% (n = 191) had microfilariae. Among them, Mansonella spp. was the most common (78.2%, n = 147), followed by Loa loa (41.4%, n = 79). The association between the two species represented 18.3% (n = 35). The specific immunoglobulins of Onchocerca volvulus were detected in 24.2% of participants (n = 87/359). Overall prevalence of L. loa was 16.8%. Hypermicrofilaremia was found in 3% (N = 14), and one participant had more than 30,000 microfilaremiae per milliliter. The frequency of L. loa did not vary according to the level of onchocerciasis transmission. Pruritus was the most common clinical sign (60.5%, n = 285) reported, mainly in microfilaremic participants (72.2%, n = 138/191). The prevalence of L. loa microfilaria in the study population was below the threshold at risk for the occurrence of serious side effects due to ivermectin. Clinical manifestations frequently observed could be exacerbated by microfilaremia in areas where onchocerciasis transmission is high.

A call for loiasis to be added to the WHO list of neglected tropical diseases

Loiasis, also called African eye worm, is not currently on WHO's list of priority neglected tropical diseases, even though the risk that individuals with high Loa loa microfilarial densities will develop potentially fatal encephalopathy when they take ivermectin has complicated efforts to use mass drug administration for onchocerciasis (river blindness) and lymphatic filariasis control in co-endemic areas. At least 10 million residents of central and west Africa are thought to have loiasis, which causes painful and itchy subcutaneous oedema, arthralgia, and discomfort when adult helminths that are 3-7 cm in length are present under the conjunctiva of the eye. High levels of microfilaraemia are associated with renal, cardiac, neurological, and other sequelae, and an increased risk of death. The public health burden of loiasis could be greatly reduced with expanded use of diagnostic tests, anthelmintic treatment, and control of the Chrysops spp (tabanid flies) vectors that transmit the parasite. Loiasis should be added to the next revision of the WHO neglected tropical disease priority list, not merely because its inclusion will support the elimination of other skin and subcutaneous neglected tropical diseases, but also because of the complications caused by loiasis itself.

Occurrence and clinical features of HIV and malaria in co-infected individuals in Osun State, Nigeria

Introduction

Human immunodeficiency virus (HIV) and malaria infections are among the major public health concerns in sub-Saharan Africa, where they are associated with high morbidity and mortality. The study was conducted to assess the occurrence and clinical features of HIV and malaria in co-infected individuals in Osun State, Nigeria.

Methods

The study was cross-sectional, which involved 422 participants who were administered structured questionnaires for socio-demographic and clinical data. Venous blood was collected for malaria parasite detection and count from One hundred and seventy-four HIV seropositive individuals. They were re-examined clinically for HIV diagnosis, CD₄ ⁺ T cell counts, and packed cell volume (PCV).

Results

The mean age of the participants was 28.48 ± 15.38 while the overall predominance of malaria among the HIV-positive patients was 11.5% (20/174). The malaria prevalence was significantly higher in female patients (P = 0.0088) and occupational status among students (P = 0.0001). Malaria/HIV co-infected patients had a significantly lower mean value of PCV (P = 0.0001), CD₄ ⁺ cell count (0.0001), and temperature (0.0001) compared to HIV-infected patients having no malaria.

Conclusion

The study showed that females had relatively higher malaria infection compared to their male counterparts. To achieve better management of HIV patients against malaria infection, proper preventive measures, antiretroviral therapy (ART), and chemoprophylaxis are a useful strategy to put in place. Also, the monitoring of CD₄ ⁺ cell count, viral load, and some hematology indices on a regular basis is crucial.

Integrated transmission assessment surveys (iTAS) of lymphatic filariasis and onchocerciasis in Cross River, Taraba and Yobe States, Nigeria

Background

Integrated transmission assessment surveys (iTAS) have been recommended for evaluation of the transmission of both lymphatic filariasis (LF) and onchocerciasis as the prevalence of both diseases moves toward their respective elimination targets in Nigeria. Therefore, we conducted an iTAS between May and December 2017 in five local government areas (LGAs), also known as implementation units (IUs), in states of Cross River, Taraba and Yobe in Nigeria.

Methods

The TAS comprised two phases: the Pre-iTAS and the iTAS itself. Three states (Cross River, Taraba and Yobe), comprising five LGAs and 20 communities that have completed five rounds of combined treatment with ivermectin and albendazole for LF and 12 total rounds of ivermectin, were selected for inclusion in the study. All participants were tested with the Filariasis Test Strip (FTS; Alere Inc.) and the Biplex rapid Diagnostic Test (RDT; identifying filaria antigens Ov16/Wb123; Abbott diagnosctics Korea Inc.). Pre iTAS included 100 children ages 5-9 in each 4 communities and 300 individuals ages 10 and older in a subset of two communities.  For the iTAS, only LGAs where antigenemia prevalence in all sampled communities during the Pre-iTAS was < 2% for LF were selected.

Results

Of the five LGAs included in the study, four met the cutoff of the Pre-iTAS and were included in the iTAS; the Ikom LGA was excluded from the iTAS due to antigenemia prevalence. A total of 11,531 school-aged children from 148 schools were tested for LF and onchocerciasis across these four LGAs, including 2873 children in Bade, 2622 children in Bekwara, 3026 children in Gashaka and 3010 children in Karim Lamido. Using the FTS, all samples from Bade and Karim Lamido were negative, whereas 0.2% of the samples from Bekwara and Gashaka were positive. Using the Biplex RDT, LF prevalence in Bade, Bekwara, Gashaka and Karim Lamido was < 0.1%, 0.5%, 0.4% and < 0.1%, respectively. Moreover, all samples from Bade and Karim Lamido were negative for onchocerciasis, whereas 3.1% and 1.8% of the samples from Bekwara and Gashaka were positive, respectively.

Conclusion

This study has provided additional information on the current burden of onchocerciasis and LF in the four IUs sampled where mass drug administration (MDA) for both infections has been ongoing for years. The study identifies that LF-MDA can be safely stopped in all four of the IUs studied, but that MDA for onchocerciasis needs to continue, even though this may pose a challenge for LF surveillance. Based on the preliminary results from all four sites, this study has fulfilled the primary objective of determining the programmatic feasibility of an iTAS as a tool to simultaneously assess onchocerciasis and LF prevalence in areas co-endemic for the two infections that have completed the recommended treatment for one or both infections, and to make decisions on how to proceed.

Graphical Abstract

Colorimetric and Real-Time Loop-Mediated Isothermal Amplification (LAMP) for Detection of Loa loa DNA in Human Blood Samples

Loiasis, caused by the filarial nematode Loa loa, is endemic in Central and West Africa. Loa loa has been associated with severe adverse reactions in high Loa-infected individuals receiving ivermectin during mass drug administration programs for the control of onchocerciasis and lymphatic filariasis. Diagnosis of loiasis still depends on microscopy in blood samples, but this is not effective for large-scale surveys. New diagnostics methods for loiasis are urgently needed. Previously, we developed a colorimetric high-sensitive and species-specific LAMP for Loa loa DNA detection. Here, we evaluate it in a set of 100 field-collected clinical samples stored as dried blood spots. In addition, Loa loa-LAMP was also evaluated in real-time testing and compared with microscopy and a specific PCR/nested PCR. A simple saponin/Chelex-based method was used to extract DNA. Colorimetric and real-time LAMP assays detected more samples with microscopy-confirmed Loa loa and Loa loa/Mansonella perstans mixed infections than PCR/nested-PCR. Samples with the highest Loa loa microfilariae counts were amplified faster in real-time LAMP assays. Our Loa loa-LAMP could be a promising molecular tool for the easy, rapid and accurate screening of patients for loiasis in endemic areas with low-resource settings. The real-time testing (feasible in a handheld device) could be very useful to rule out high-microfilariae loads in infected patients.

Black flies and Onchocerciasis: Knowledge, attitude and practices among inhabitants of Alabameta, Osun State, Southwestern, Nigeria

Background and objectives

This study reports knowledge of residents of Alabameta community, Osun State, Nigeria on the bioecology and socio-economic burden of black flies and onchocerciasis.

Methods

Using structured questionnaires and Focus Group Discussion (FGD), a total of 150 community respondents participated in the study.

Results

The knowledge of the residents on the existence of black flies in the community was significant (p<0.05) as all the 150 respondents confirmed the presence of black flies with the local name ‘Amukuru’ i.e causing itching. However, their lack of knowledge of the flies breeding site (104) (69%), prevention (134) (89%), cause (132) (88%), and treatment (133) (89%) of onchocerciasis was profound. Majority 147(98%) of the respondents reported that flies bite more in the wet season as against dry season 3(2%) and have a higher affinity (124) (82%) for biting the leg than any other part of the body. A larger percentage (89%) of the respondents are unaware of any medication for the treatment of onchocerciasis while 11% are aware. There had been no sensitization on onchocerciasis according to 89% of the respondents.

Conclusion

Due to lack of resident’s knowledge on black flies bioecology which may continuously expose them to the bite of the flies and ultimately infection, it is paramount that the Osun State government and the NTD implementing partner map out new public health education strategies during routine Mass Administration of Medicines with Ivermectin with a view to preventing onchocerciasis infection as well as man-vector contact.

Genomic analysis of Staphylococcus aureus from the West African Dwarf (WAD) goat in Nigeria

Background

Staphylococcus aureus can colonize various host species, and human-animal interaction is a significant factor for cross-species transmission. However, data on S. aureus colonization in animals, particularly on ruminants in close contact with humans, is limited. The West African Dwarf (WAD) goat is among the earliest domesticated ruminant associated with rural dwellers and small-holder farmers in sub-Saharan Africa. This study aimed to investigate the population structure, antibiotic resistance, and virulence gene determinants of S. aureus from the WAD goat in Nigeria.

Methods

Nasal samples were obtained from the WAD goat in five markets in Osun State, South-West Nigeria. S. aureus was characterized by antibiotic susceptibility testing, detection of virulence determinants, spa typing, and multilocus sequence typing (MLST). Representative isolates were selected for whole-genome sequencing, biofilm, and cytotoxicity assay.

Results

Of the 726 nasal samples obtained from the WAD goat, 90 S. aureus (12.4%) were recovered. Overall, 86 isolates were methicillin-susceptible, and four were mecA-positive (i.e., methicillin-resistant S. aureus [MRSA]). A diverse S. aureus clonal population was observed (20 sequence types [STs] and 37 spa types), while 35% (13/37) and 40% (8/20) were new spa types and STs, respectively. Eleven MLST clonal complexes (CC) were identified (CC1, CC5, CC8, CC15, CC30, CC45, CC97, CC121, CC133, CC152, CC522). The MRSA isolates were designated as t127-ST852-CC1-SCCmec type VII, t4690-ST152-CC152-SCCmec type Vc, and t8821-ST152-CC152-SCCmec type Vc. Phylogenetic analysis revealed that 60% (54/90) of all isolates were associated with ruminant lineages (i.e., CC133, CC522). Panton-Valentine Leukocidin (PVL)-positive S. aureus was identified in CC1, CC30, CC121, and CC152. For the CC522 isolates, we illustrate their pathogenic potential by the detection of the toxic shock syndrome gene and hemolysins, as well as their strong cytotoxicity and ability to form biofilms.

Conclusions

This is the first detailed investigation on the genomic content of S. aureus from the WAD goat in Nigeria. The S. aureus population of the WAD goat consists mainly of ruminant-associated lineages (e.g., CC133, CC522), interspersed with human-associated clones, including PVL-positive MRSA CC1 and CC152.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-021-00987-8.

Biting behaviour and infectivity of Simulium damnosum complex with Onchocerca parasite in Alabameta, Osun State, Southwestern, Nigeria

A longitudinal study was carried out to investigate species composition, seasonal abundance, parity and transmission potential of Simulium damnosum complex in Alabameta community in Osun State, Southwestern, Nigeria. Adult Simulium damnosum complex were collected along Owena River, Alabameta, by two dark complexioned vector collectors from 07:00hr to 18:00hr weekly using collecting tubes from November 2014 to April 2015. The flies were morphologically identified and dissected for the purpose of detecting Onchocerca parasite using dissecting microscope. The Monthly Biting Rate (MBR) of flies was determined using World Health Organization standard formula. A total of four hundred and forty flies were collected during the study period with all of them identified as forest species of Simulium damnosum complex. There was significant variation in monthly collection of the flies with the month of November having the highest number of flies (194) (44%) while the month of April recorded the lowest number of flies (31) (7%) (p<0.05). The morning biting peak (09hr - 11hr) (137) was higher than the evening biting peak (15hr -17hr) (64) (p<0.05) while nulliparous flies (294) (67%) were more abundant than the parous flies (146) (33%) (p<0.05). There was absence of infection (zero infectivity) of the flies (p<0.05). The zero infectivity in the flies may plausibly indicate the possibility of zero transmission of Onchocerca parasite in the community which if sustained over a period of time may signify the possibility of onchocerciasis elimination. Also, the presence of forest species of the flies reduces the risk of resident's intense exposure to blinding savannah strain of onchocerciasis.

An Adult Loa loa Worm in the Upper Eyelid: An Atypical Presentation of Loiasis in the United States

Purpose. To report a case of ocular involvement of Loa loa parasite. Observations. We present a rare case report of a Loiasis diagnosed in the United States from a patient presenting with subcutaneous migration of an adult worm within an eyelid who was found to have systemic disease with microfilaria in his blood. This is the second report in the United States and the eighth case in published literature worldwide. Conclusions and Importance. Due to the relatively mild disease course, Loiasis is relatively ignored in public health in low resource health districts. Understandably, the focus of public health in endemic areas must focus on basic health needs like malnutrition and diseases that entail a greater disease burden. As globalization has increased the amount of trade of physical goods, the effect of immigration also has implications for the spread of infectious disease. Medical practitioners in the United States should be aware of endemic diseases from foreign lands.

Biting Rates and Onchocerca Infectivity Status of Black Flies from the Simulium damnosum Complex (Diptera: Simuliidae) in Osun State, Nigeria

The Simulium damnosum Theobald complex transmits Onchocerca volvulus Leuckart (Spirurida: Onchocercidae), the causative agent of onchocerciasis. Recent evidence suggests that control efforts have strongly suppressed parasite populations, but vector surveillance is needed in parts of Africa where the disease remains endemic. Here, studies on biting rates and infectivity status of suspected vector species were conducted in three onchocerciasis-endemic areas, namely Iwo, Ede, and Obokun, in Osun State, Nigeria. A total of 3,035 black flies were collected between October 2014 and September 2016, and examined for parity and parasites using standard methods. A separate collection of 2,000 black flies was pool-screened for infectivity using polymerase chain reaction (PCR) amplification of the O-150 marker. Results showed that parous flies were significantly less common than nulliparous flies with overall parous rates of 8.02% in Iwo and 35.38% in Ede at the end of the study period. Obokun had a parous rate of 22.22% obtained in the first year only. None of the dissected parous flies were infected with O. volvulus and PCR assays showed no amplification of O-150 O. volvulus-specific repeats in head and body pools. However, annual biting rates exceeded the World Health Organization threshold of 1,000 bites/person/yr. Thus it appears that, with such high rates of biting, even low levels of vector infection can sustain onchocerciasis in African communities.

Effect of a Single Standard Dose (150-200 μg/kg) of Ivermectin on Loa loa Microfilaremia: Systematic Review and Meta-analysis

Background

In central Africa, millions of individuals infected with Loa loa have received the anthelminthic drug ivermectin (IVM) as part of mass drug administration (MDA) campaigns targeting onchocerciasis control or elimination. Nonetheless, the parasitological surveys that are occasionally conducted to evaluate the impact of IVM treatments on Onchocerca volvulus do not include an assessment of the extra benefits of those MDA campaigns on L. loa.

Methods

We conducted a systematic review of trials on the effect of a single standard (150–200 μg/kg) dose of IVM on L. loa microfilarial density (MFD). The dynamics of MFD over 365 days of treatment were described using multilevel regression and latent class modeling.

Results

IVM brings about a rapid, dramatic, and sustained decrease, with reduction rates of 60%, 75%, 85%, and 90% on day 1 (D1), D2, D7, and D365, respectively. At D365, no participants (0/238) with an initial MFD of <20 000 microfilariae (mf)/mL were at risk of postivermectin severe adverse events, and only 1/57 individuals with an initial MFD of ≥20 000 mf/mL presented with an MFD above this value. The main predictor of post-treatment MFD was the pretreatment value, but this post-treatment value varied little between D8 and D365 regardless of the pretreatment level.

Conclusions

A single dose of IVM is very effective at substantially reducing L. loa MFD for at least a year, irrespective of the initial level of parasitemia. Individuals treated with IVM are probably not any more at risk of severe adverse events when retreated 1 year later.

A cross-sectional study of the filarial and Leishmania co-endemicity in two ecologically distinct settings in Mali

BACKGROUND

Filariasis and leishmaniasis are two neglected tropical diseases in Mali. Due to distribution and associated clinical features, both diseases are of concern to public health. The goal of this study was to determine the prevalence of co-infection with filarial (Wuchereria bancrofti and Mansonella perstans) and Leishmania major parasites in two ecologically distinct areas of Mali, the Kolokani district (villages of Tieneguebougou and Bougoudiana) in North Sudan Savanna area, and the district of Kolondieba (village of Boundioba) in the South Sudan Savanna area.

METHODS

The prevalence of co-infection (filarial and Leishmania) was measured based on (i) Mansonella perstans microfilaremia count and/or filariasis immunochromatographic test (ICT) for Wuchereria bancrofti-specific circulating antigen, and (ii) the prevalence of delayed type hypersensitivity (DTH) responses to Leishmania measured by leishmanin skin test (LST).

RESULTS

In this study, a total of 930 volunteers between the age of 18 and 65 were included from the two endemic areas of Kolokani and Kolondieba. In general, in both areas, filarial infection was more prevalent than Leishmania infection with an overall prevalence of 15.27% (142/930) including 8.7% (81/930) for Mansonella perstans and 8% (74/930) for Wuchereria bancrofti-specific circulating antigen. The prevalence of Leishmania major infection was 7.7% (72/930) and was significantly higher in Tieneguebougou and Bougoudiana (15.05%; 64/425) than in Boundioba (2.04%; 8/505) (χ2 = 58.66, P < 0.0001). Among the filarial infected population, nearly 10% (14/142) were also positive for Leishmania with an overall prevalence of co-infection of 1.50% (14/930) varying from 2.82% (12/425) in Tieneguebougou and Bougoudiana to 0.39% (2/505) in Boundioba (P = 0.0048).

CONCLUSION

This study established the existence of co-endemicity of filarial and Leishmania infections in specific regions of Mali. Since both filarial and Leishmania infections are vector-borne with mosquitoes and sand flies as respective vectors, an integrated vector control approach should be considered in co-endemic areas. The effect of potential interaction between filarial and Leishmania parasites on the disease outcomes may be further studied.