ABSTRACT
BACKGROUND: Indoor residual spraying (IRS) is a common vector control strategy in countries with high malaria burden. Historically, social norms have prevented women from working in IRS programmes. The Bioko Island Malaria Elimination Project has actively sought to reduce gender inequality in malaria control operations for many years by promoting women's participation in IRS. METHODS: This study investigated the progress of female engagement and compared spray productivity by gender from 2010 to 2021, using inferential tests and multivariable regression. Spray productivity was measured by rooms sprayed by spray operator per day (RSOD), houses sprayed by spray operator per day (HSOD), and the daily productivity ratio (DPR), defined as the ratio of RSOD to HSOD, which standardized productivity by house size. RESULTS: The percentage of women participating in IRS has increased over time. The difference in DPR comparing male and female spray operators was only statistically significant (p < 0.05) for two rounds, where the value was higher for women compared to men. Regression analyses showed marginal, significant differences in DPR between men and women, but beta coefficients were extremely small and thus not indicative of a measurable effect of gender on operational performance. CONCLUSIONS: The quantitative analyses of spray productivity are counter to stigmatizing beliefs that women are less capable than male counterparts during IRS spray rounds. The findings from this research support the participation of women in IRS campaigns, and a renewed effort to implement equitable policies and practices that intentionally engage women in vector control activities.
Subject(s)
Insecticides , Malaria , Humans , Male , Female , Equatorial Guinea , Mosquito Control , Malaria/prevention & controlABSTRACT
Since the discovery of Legionnaires' disease (LD), limited progress has been made in understanding the epidemiology of sporadic cases of LD. Outbreaks have confirmed that air conditioning and potable water systems can be sources of community-acquired LD. However, studying the association between water quality and LD incidence has been challenging due to the heterogeneity of water systems across large geographic areas. Furthermore, although seasonal trends in incidence have been linked to increased rainfall and temperatures, the large geographic units have posed similar difficulties. To address this issue, a retrospective ecological study was conducted in Washington, DC, from 2001 to 2019. The study identified aseasonal pattern of LD incidence, with the majority of cases occurring between June and December, peaking in August, October, and November. Increased temperature was found to be associated with LD incidence. In surface water, higher concentrations of manganese, iron, and strontium were positively associated with LD, while aluminum and orthophosphate showed a negative association. Intreatment plant water, higher concentrations of total organic carbon, aluminum, barium, and chlorine were positively associated with LD, while strontium, zinc, and orthophosphate showed a negative association. The results for orthophosphates and turbidity were inconclusive, indicating the need for further research.
Subject(s)
Legionella pneumophila , Legionnaires' Disease , Humans , Legionnaires' Disease/epidemiology , Legionnaires' Disease/etiology , Water Quality , Retrospective Studies , Seasons , Aluminum , District of Columbia/epidemiology , Water Microbiology , Disease Outbreaks , TemperatureABSTRACT
BACKGROUND: In 2017, several new housing districts were constructed on Bioko Island, Equatorial Guinea. This case study assessed the impact construction projects had on mosquito larval habitats and the effectiveness of larval source management in reducing malaria vector density within the surrounding area. METHODS: Anopheline larval presence was assessed at 11 new construction sites by the proportion of larval habitats containing Anopheline pupae and late instar larval stages. Bacillus thuringiensis israelensis (Bti) larvicide was applied weekly to nine locations for 30 weeks, while two locations received no larvicide and acted as controls. Adult mosquito density was monitored via human landing collections in adjacent communities of six construction sites, including the two control sites. RESULTS: The sites that received Bti had significantly lower observation rates of both pupae (3.2% vs. 18.0%; p < 0.001) and late instar Anopheles spp. mosquitoes (14.1 vs. 43.6%; p < 0.001) compared to the two untreated sites. Anopheles spp. accounted for 67% of mosquitoes collected with human landing collections and were captured at significantly lower levels in communities adjacent to treated construction sites compared to untreated sites (p < 0.001), with an estimated 38% reduction in human biting rate (IRR: 0.62, 95% CI IRR: 0.55, 0.69). Seven months after the start of the study, untreated sites were treated due to ethical concerns given results from treatment sties, necessitating immediate Bti application. The following week, the number of habitats, the proportion of larval sites with Anopheles spp. pupae, late instars, and adult biting rates in adjacent communities to these sites all decreased to comparable levels across all sites. CONCLUSION: Findings suggest larval source management represents an effective intervention to suppress mosquito populations during infrastructure development. Incorporating larval source management into ongoing and planned construction initiatives represents an opportunity to fine tune vector control in response to anthropogenetic changes. Ideally, this should become standard practice in malaria-endemic regions in order to reduce viable mosquito habitats that are common by-products of construction.
Subject(s)
Anopheles , Bacillus thuringiensis , Malaria , Animals , Humans , Anopheles/physiology , Malaria/epidemiology , Mosquito Control/methods , Larva , Urban Renewal , Mosquito Vectors , Pupa , EcosystemABSTRACT
BACKGROUND: During March of 2020 the Centers for Disease Control and Prevention (CDC) announced non-pharmaceutical intervention (NPI) guidance as the primary mitigation strategy against growing COVID-19 community spread due to the absence of a vaccine or effective treatment at that time. CDC guidance states that NPIs are most effective when instituted in an early, targeted, and layered fashion. NPIs are effective in slowing spread, and measures should be custom-tailored to each population. This study examines factors associated with implementation and timing of NPI interventions across large public and private U.S. universities at the onset of the COVID-19 pandemic. METHODS: NPI decisions of interest include when U.S. universities canceled international travel, shifted to online learning, moved faculty/staff to remote work, limited campus housing, and closed campus for all non-essential personnel. Cox proportional hazard analyses of retrospective data were conducted to assess the time to NPI events. Hazard ratios were calculated for university governance, campus setting, religious affiliation, health infrastructure, faculty diversity, and student demographics. The methods control for variance inflation factors, COVID case prevalence, and time varying covariates of spring break and states' state of emergency (SOE) orders. This study captures NPI decisions at 575 U.S. universities during spring of 2020 which affected the movement of seven million students and two million employees. RESULTS: Universities located in districts represented by Democratic party congressional members reported earlier NPI implementation than Republican (Cox proportional hazard ratio (HR) range 0.61-0.80). University religious affiliation was not associated with the timing any of the NPI decisions. Universities with more diverse faculty showed an association with earlier NPI implementation (HR range 0.65-0.76). The existence of university-affiliated health infrastructure was not associated with NPI timing. CONCLUSION: University NPI implementation was largely driven by local COVID-19 epidemiology, culture and political concerns. The timing of university NPI decisions varied by regional politics, faculty demographics, university governance, campus setting, and foreign student prevalence adjusting for COVID-19 state case prevalence and spring break timing. Religious affiliation and presence of university health infrastructure were not associated with timing.
Subject(s)
COVID-19 , Pandemics , Humans , Retrospective Studies , SARS-CoV-2 , Survival Analysis , UniversitiesABSTRACT
BACKGROUND: The radical cure of Plasmodium vivax and P. ovale requires treatment with primaquine or tafenoquine to clear dormant liver stages. Either drug can induce haemolysis in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency, necessitating screening. The reference diagnostic method for G6PD activity is ultraviolet (UV) spectrophotometry; however, a universal G6PD activity threshold above which these drugs can be safely administered is not yet defined. Our study aimed to quantify assay-based variation in G6PD spectrophotometry and to explore the diagnostic implications of applying a universal threshold. METHODS AND FINDINGS: Individual-level data were pooled from studies that used G6PD spectrophotometry. Studies were identified via PubMed search (25 April 2018) and unpublished contributions from contacted authors (PROSPERO: CRD42019121414). Studies were excluded if they assessed only individuals with known haematological conditions, were family studies, or had insufficient details. Studies of malaria patients were included but analysed separately. Included studies were assessed for risk of bias using an adapted form of the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Repeatability and intra- and interlaboratory variability in G6PD activity measurements were compared between studies and pooled across the dataset. A universal threshold for G6PD deficiency was derived, and its diagnostic performance was compared to site-specific thresholds. Study participants (n = 15,811) were aged between 0 and 86 years, and 44.4% (7,083) were women. Median (range) activity of G6PD normal (G6PDn) control samples was 10.0 U/g Hb (6.3-14.0) for the Trinity assay and 8.3 U/g Hb (6.8-15.6) for the Randox assay. G6PD activity distributions varied significantly between studies. For the 13 studies that used the Trinity assay, the adjusted male median (AMM; a standardised metric of 100% G6PD activity) varied from 5.7 to 12.6 U/g Hb (p < 0.001). Assay precision varied between laboratories, as assessed by variance in control measurements (from 0.1 to 1.5 U/g Hb; p < 0.001) and study-wise mean coefficient of variation (CV) of replicate measures (from 1.6% to 14.9%; p < 0.001). A universal threshold of 100% G6PD activity was defined as 9.4 U/g Hb, yielding diagnostic thresholds of 6.6 U/g Hb (70% activity) and 2.8 U/g Hb (30% activity). These thresholds diagnosed individuals with less than 30% G6PD activity with study-wise sensitivity from 89% (95% CI: 81%-94%) to 100% (95% CI: 96%-100%) and specificity from 96% (95% CI: 89%-99%) to 100% (100%-100%). However, when considering intermediate deficiency (<70% G6PD activity), sensitivity fell to a minimum of 64% (95% CI: 52%-75%) and specificity to 35% (95% CI: 24%-46%). Our ability to identify underlying factors associated with study-level heterogeneity was limited by the lack of availability of covariate data and diverse study contexts and methodologies. CONCLUSIONS: Our findings indicate that there is substantial variation in G6PD measurements by spectrophotometry between sites. This is likely due to variability in laboratory methods, with possible contribution of unmeasured population factors. While an assay-specific, universal quantitative threshold offers robust diagnosis at the 30% level, inter-study variability impedes performance of universal thresholds at the 70% level. Caution is advised in comparing findings based on absolute G6PD activity measurements across studies. Novel handheld quantitative G6PD diagnostics may allow greater standardisation in the future.
Subject(s)
Glucosephosphate Dehydrogenase Deficiency/diagnosis , Glucosephosphate Dehydrogenase Deficiency/metabolism , Glucosephosphate Dehydrogenase/metabolism , Spectrophotometry , Adolescent , Adult , Aged , Aged, 80 and over , Antimalarials/therapeutic use , Child , Child, Preschool , Female , Glucosephosphate Dehydrogenase Deficiency/drug therapy , Humans , Infant , Infant, Newborn , Malaria/epidemiology , Male , Middle Aged , Young AdultABSTRACT
[This corrects the article DOI: 10.1371/journal.pmed.1003084.].
ABSTRACT
BACKGROUND: Quality control of indoor residual spraying (IRS) is necessary to ensure that spray operators (SOs) deposit the correct concentration of insecticide on sprayed structures, while also confirming that spray records are not being falsified. METHODS: Using high-performance liquid chromatography (HPLC), this study conducted quality control of the organophosphate insecticide pirimiphos-methyl (Actellic 300CS), during the 2018 IRS round on Bioko Island, Equatorial Guinea. Approximately 60 SOs sprayed a total of 67,721 structures in 16,653 houses during the round. Houses that were reportedly sprayed were randomly selected for quality control testing. The SOs were monitored twice in 2018, an initial screening in March followed by sharing of results with the IRS management team and identification of SOs to be re-trained, and a second screening in June to monitor the effectiveness of training. Insecticide samples were adhesive-lifted from wooden and cement structures and analysed using HPLC. RESULTS: The study suggests that with adequate quality control measures and refresher training, suboptimal spraying was curtailed, with a significant increased concentration delivered to the bedroom (difference = 0.36, P < 0.001) and wooden surfaces (difference 0.41, P = 0.001). Additionally, an increase in effective coverage by SOs was observed, improving from 80.7% in March to 94.7% in June after re-training (McNemar's test; P = 0.03). CONCLUSIONS: The ability to randomly select, locate, and test houses reportedly sprayed within a week via HPLC has led to improvements in the performance of SOs on Bioko Island, enabling the project to better evaluate its own performance.
Subject(s)
Insecticides/administration & dosage , Malaria/prevention & control , Mosquito Control/standards , Organothiophosphorus Compounds/administration & dosage , Aerosols , Animals , Chromatography, High Pressure Liquid/economics , Equatorial Guinea , Housing , Humans , Islands , Mosquito Control/methods , Organophosphates/analysis , Quality Control , Seasons , Time FactorsABSTRACT
Human yaws has historically been endemic to Kenya, but current epidemiologic data are lacking. We report seroprevalence for Treponema pallidum antibodies in olive baboons (Papio anubis) and vervet monkeys (Chlorocebus pygerythrus) in Laikipia County, Kenya. Our results suggest endemicity of the yaws bacterium in monkeys, posing a possible zoonotic threat to humans.
Subject(s)
Antibodies, Bacterial/immunology , Monkey Diseases/epidemiology , Monkey Diseases/microbiology , Seroepidemiologic Studies , Treponema pallidum , Yaws/veterinary , Animals , Kenya/epidemiology , Prevalence , Primates , Public Health Surveillance , Treponema pallidum/immunologyABSTRACT
BACKGROUND: To reduce the risk of drug-induced haemolysis, all patients should be tested for glucose-6-phosphate dehydrogenase (G6PD) deficiency (G6PDd) prior to prescribing primaquine (PQ)-based radical cure for the treatment of vivax malaria. This systematic review and individual patient meta-analysis assessed the utility of a qualitative lateral flow assay from Access Bio/CareStart (Somerset, NJ) (CareStart Screening test for G6PD deficiency) for the diagnosis of G6PDd compared to the gold standard spectrophotometry (International Prospective Register of Systematic Reviews [PROSPERO]: CRD42019110994). METHODS AND FINDINGS: Articles published on PubMed between 1 January 2011 and 27 September 2019 were screened. Articles reporting performance of the standard CSG from venous or capillary blood samples collected prospectively and considering spectrophotometry as gold standard (using kits from Trinity Biotech PLC, Wicklow, Ireland) were included. Authors of articles fulfilling the inclusion criteria were contacted to contribute anonymized individual data. Minimal data requested were sex of the participant, CSG result, spectrophotometry result in U/gHb, and haemoglobin (Hb) reading. The adjusted male median (AMM) was calculated per site and defined as 100% G6PD activity. G6PDd was defined as an enzyme activity of less than 30%. Pooled estimates for sensitivity and specificity, unconditional negative predictive value (NPV), positive likelihood ratio (LR+), and negative likelihood ratio (LR-) were calculated comparing CSG results to spectrophotometry using a random-effects bivariate model. Of 11 eligible published articles, individual data were available from 8 studies, 6 from Southeast Asia, 1 from Africa, and 1 from the Americas. A total of 5,815 individual participant data (IPD) were available, of which 5,777 results (99.3%) were considered for analysis, including data from 3,095 (53.6%) females. Overall, the CSG had a pooled sensitivity of 0.96 (95% CI 0.90-0.99) and a specificity of 0.95 (95% CI 0.92-0.96). When the prevalence of G6PDd was varied from 5% to 30%, the unconditional NPV was 0.99 (95% CI 0.94-1.00), with an LR+ and an LR- of 18.23 (95% CI 13.04-25.48) and 0.05 (95% CI 0.02-0.12), respectively. Performance was significantly better in males compared to females (p = 0.027) but did not differ significantly between samples collected from capillary or venous blood (p = 0.547). Limitations of the study include the lack of wide geographical representation of the included data and that the CSG results were generated under research conditions, and therefore may not reflect performance in routine settings. CONCLUSIONS: The CSG performed well at the 30% threshold. Its high NPV suggests that the test is suitable to guide PQ treatment, and the high LR+ and low LR- render the test suitable to confirm and exclude G6PDd. Further operational studies are needed to confirm the utility of the test in remote endemic settings.
Subject(s)
Diagnostic Tests, Routine , Glucosephosphate Dehydrogenase Deficiency/diagnosis , Glucosephosphate Dehydrogenase/genetics , Primaquine/therapeutic use , Diagnostic Tests, Routine/methods , Endemic Diseases , Female , Glucosephosphate Dehydrogenase Deficiency/drug therapy , Humans , Malaria/drug therapy , Malaria/epidemiology , Malaria, Vivax/epidemiology , Male , Point-of-Care Systems , Primaquine/adverse effects , Sensitivity and SpecificityABSTRACT
BACKGROUND: Malaria transmission continues to occur in Haiti, with 25,423 confirmed cases of Plasmodium falciparum and 161,236 suspected infections reported in 2012. At low prevalence levels, passive surveillance measures, which rely primarily on reports from health systems, becomes less appropriate for capturing annual malaria incidence. To improve understanding of malaria transmission in Haiti, participants from the Ouest and Sud-Est departments were screened using a highly sensitive enzyme-linked immunosorbent assay (ELISA). METHODS: Between February and May 2013, samples were collected from four different sites including a rural community, two schools, and a clinic located in the Ouest and Sud-Est departments of Haiti. A total of 815 serum samples were screened for malaria antibodies using an indirect ELISA coated with vaccine candidates apical membrane antigen (AMA-1) and merozoite surface protein-1 (MSP-119). The classification of previous exposure was established by using a threshold value that fell three standard deviations above the mean absorbance for suspected seronegative population members (OD of 0.32 and 0.26 for AMA-1 and MSP-1, respectively). The observed seroprevalence values were used to fit a modified reverse catalytic model to yield estimates of seroconversion rates. RESULTS: Of the samples screened, 172 of 815 (21.1%) were AMA-1 positive, 179 of 759 (23.6%) were MSP-119 positive, and 247 of 815 (30.3%) were positive for either AMA-1 or MSP-1; indicating rates of previous infections between 21.1% and 30.3%. Not surprisingly, age was highly associated with the likelihood of previous infection (p-value <0.001). After stratification by age, the estimated seroconversion rate indicated that the annual malaria transmission in the Ouest and Sud-Est department is approximately 2.5% (95% CI SCR: 2.2%, 2.8%). CONCLUSIONS: These findings suggest that despite the absence of sustained malaria control efforts in Haiti, transmission has remained relatively low over multiple decades. Elimination in Haiti appears to be feasible; however, surveillance must continue to be strengthened in order to respond to areas with high transmission and measure the impact of future interventions.
Subject(s)
Antibodies, Protozoan/blood , Malaria, Falciparum/epidemiology , Malaria, Falciparum/transmission , Adolescent , Adult , Aged , Antigens, Protozoan/immunology , Child , Child, Preschool , Cross-Sectional Studies , Female , Haiti/epidemiology , Humans , Malaria, Falciparum/immunology , Male , Membrane Proteins/immunology , Merozoite Surface Protein 1/immunology , Middle Aged , Plasmodium falciparum/immunology , Protozoan Proteins/immunology , Seroepidemiologic Studies , Young AdultABSTRACT
Quantitative diagnosis of glucose-6-phosphate dehydrogenase (G6PD) deficiency is essential for the safe administration of 8-aminoquinoline based radical cure for the treatment of Plasmodium vivax infections. Here, we present the PreQuine Platform (IVDS, USA), a quantitative biosensor that uses a dual-analyte assay for the simultaneous measurement of Hemoglobin (Hgb) levels and G6PD enzyme activity within the same sample. The platform relies on a downloadable mobile application. The device requires 10µl of whole blood and works with a reflectance-based meter. Comparing the G6PD measurement normalized by Hgb of 12 samples from the PreQuine Platform with reference measurements methods (spectrophotometry, Pointe Scientific, USA and hemoglobin meter, HemoCue, Sweden) showed a positive and significant agreement with a slope of 1.0091 and an intercept of -0.0379 under laboratory conditions. Next steps will be to conduct field trials in Bangladesh, Cambodia, and the USA to assess diagnostic performance, user friendliness and acceptance.
Subject(s)
Glucosephosphate Dehydrogenase Deficiency , Glucosephosphate Dehydrogenase , Hemoglobins , Humans , Glucosephosphate Dehydrogenase/metabolism , Glucosephosphate Dehydrogenase/blood , Glucosephosphate Dehydrogenase Deficiency/diagnosis , Glucosephosphate Dehydrogenase Deficiency/blood , Hemoglobins/analysis , Hemoglobins/metabolism , Biosensing Techniques/methods , Malaria, Vivax/diagnosis , Malaria, Vivax/blood , AminoquinolinesABSTRACT
Introduction: Coxiella burnetii (C. burnetii)-infected livestock and wildlife have been epidemiologically linked to human Q fever outbreaks. Despite this growing zoonotic threat, knowledge of coxiellosis in wild animals remains limited, and studies to understand their epidemiologic role are needed. In C. burnetii-endemic areas, ticks have been reported to harbor and spread C. burnetii and may serve as indicators of risk of infection in wild animal habitats. Therefore, the aim of this study was to compare molecular techniques for detecting C. burnetii DNA in ticks. Methods: In total, 169 ticks from wild animals and cattle in wildlife conservancies in northern Kenya were screened for C. burnetii DNA using a conventional PCR (cPCR) and two field-friendly techniques: Biomeme's C. burnetii qPCR Go-strips (Biomeme) and a new C. burnetii PCR high-resolution melt (PCR-HRM) analysis assay. Results were evaluated, in the absence of a gold standard test, using Bayesian latent class analysis (BLCA) to characterize the proportion of C. burnetii positive ticks and estimate sensitivity (Se) and specificity (Sp) of the three tests. Results: The final BLCA model included main effects and estimated that PCR-HRM had the highest Se (86%; 95% credible interval: 56-99%), followed by the Biomeme (Se = 57%; 95% credible interval: 34-90%), with the estimated Se of the cPCR being the lowest (24%, 95% credible interval: 10-47%). Specificity estimates for all three assays ranged from 94 to 98%. Based on the model, an estimated 16% of ticks had C. burnetii DNA present. Discussion: These results reflect the endemicity of C. burnetii in northern Kenya and show the promise of the PCR-HRM assay for C. burnetii surveillance in ticks. Further studies using ticks and wild animal samples will enhance understanding of the epidemiological role of ticks in Q fever.
ABSTRACT
AIMS: Coxiella burnetii is a highly infectious organism that is easily spread through aerosols causing Q fever in humans. Ticks can harbour and transmit C. burnetii to animals, contributing to disease maintenance. Our aim was to examine the presence of C. burnetii in ticks in Uganda. METHODS AND RESULTS: In this study, ticks were collected from five Ugandan districts and tested by real-time PCR for C. burnetii (Coxiella outer membrane protein 1 gene). A total of 859 tick pools (9602 individual ticks) were tested, and pool positivity for C. burnetii was 5.5% (n = 47). Pooled prevalence differed by district; the highest was Luwero (7.3%), then Gulu (6.6%), and Kasese had the lowest (1.3%). However, district variation was not statistically significant (Fisher's exact = 0.07). Ticks collected from dogs and cats had the highest positivity rates [23/47, (48.9%)] followed by livestock (cattle, goats, sheep, and pigs) [18/47, (38.3%)] and vegetation [6/47, (12.8%)]. Haemaphysalis elliptica had the highest infection rates, followed by Rhipicephalus appendiculatus, Amblyomma variegatum and Rhipicephalus decoloratus had similar prevalence. CONCLUSIONS: Although ticks are not the primary transmitters of C. burnetii to humans, pathogen detection in ticks can be an indirect indicator of risk among animal hosts. Vulnerable populations, including occupations with close animal contact such as farming, butchery, and veterinary practice, have an increased risk of C. burnetii exposure. Veterinarians and clinicians should be aware that C. burnetii may cause human and animal illness in these regions.
ABSTRACT
BACKGROUND: Surveillance data documenting tick and tick-borne disease (TBD) prevalence is needed to develop risk assessments and implement control strategies. Despite extensive research in Africa, there is no standardized, comprehensive review. METHODS: Here we tackle this knowledge gap, by producing a comprehensive review of research articles on ticks and TBD between 1901 and 2020 in Chad, Djibouti, Ethiopia, Kenya, Tanzania, and Uganda. Over 8356 English language articles were recovered. Our search strategy included 19 related MeSH terms. Articles were reviewed, and 331 met inclusion criteria. Articles containing mappable data were compiled into a standardized data schema, georeferenced, and uploaded to VectorMap. RESULTS: Tick and pathogen matrixes were created, providing information on vector distributions and tick-pathogen associations within the six selected African countries. CONCLUSIONS: These results provide a digital, mappable database of current and historical tick and TBD distributions across six countries in Africa, which can inform specific risk modeling, determine surveillance gaps, and guide future surveillance priorities.
Subject(s)
Tick-Borne Diseases , Ticks , Animals , Ethiopia , Kenya , Tanzania , Tick-Borne Diseases/epidemiology , Africa South of the SaharaABSTRACT
BACKGROUND: Malaria is a significant public health concern in Haiti where approximately 30,000 cases are reported annually with CDC estimates as high as 200,000. Malaria infections in Haiti are caused almost exclusively by Plasmodium falciparum, while a small number of Plasmodium malariae and an even smaller number of putative Plasmodium vivax infections have been reported. The lack of confirmed P. vivax infections in Haiti could be due to the genetic background of native Haitians. Having descended from West African populations, many Haitians could be Duffy negative due to a single nucleotide polymorphism from thymine to cytosine in the GATA box of the promoter region of the Duffy antigen receptor for chemokines (DARC) gene. This mutation, encoded by the FYES allele, eliminates the expression of the Duffy antigen on erythrocytes, which reduces invasion by P. vivax. This study investigated the frequency of the FYES allele and P. vivax infections in malaria patients with the goal of uncovering factors for the lack of P. vivax infections reported in Haiti. METHODS: DNA was extracted from dried blood spots collected from malaria patients at four clinic locations in Haiti. The samples were analysed by polymerase chain reaction (PCR) for the presence of the P. vivax small subunit ribosomal RNA gene. PCR, sequencing, and restriction enzyme digestion were used to detect the presence of the FYES allele. Matched samples were examined for both presence of P. vivax and the FYES allele. RESULTS: No cases of P. vivax were detected in any of the samples (0/136). Of all samples tested for the FYES allele, 99.4% had the FYES allele (163/164). Of the matched samples, 99% had the FYES allele (98/99). CONCLUSIONS: In this preliminary study, no cases of P. vivax were confirmed by PCR and 99% of the malaria patients tested carried the FYES allele. The high frequency of the FYES allele that silences erythroid expression of the Duffy antigen offers a biologically plausible explanation for the lack of P. vivax infections observed. These results provide insights on the host susceptibility for P. vivax infections that has never before been investigated in Haiti.
Subject(s)
Disease Resistance , Duffy Blood-Group System/genetics , Malaria, Vivax/genetics , Receptors, Cell Surface/genetics , Gene Frequency , Haiti , Humans , Polymerase Chain Reaction , Polymorphism, Restriction Fragment Length , Polymorphism, Single Nucleotide , Promoter Regions, Genetic , Sequence Analysis, DNAABSTRACT
Bartonella can infect a variety of mammals including humans and has been detected in the Americas, Europe, Africa, and Asia. Roughly two-thirds of identified Bartonella species are found and maintained in rodent reservoirs, with some of these species linked to human infections. Rodents (N=236) were caught from the Sahiwal division of Punjab, Pakistan and tested for Bartonella using PCR targeting gltA and rpoB genes, followed by sequencing of rpoB-positive samples. Genetic relatedness to other published Bartonella spp. rpoB gene sequences were examined using BLAST and phylogenetic analysis. Overall, 7.62% (18/236) of rodents were positive for both gltA and rpoB fragments. Rattus rattus and R. norvegicus had 7.94% (12/151) and 7.05% (6/85) positivity rates for Bartonella DNA, respectively. Phylogenetic analysis revealed a close relatedness between Bartonella spp. from Pakistan to Bartonella spp. from China, Nepal, and Malaysia. This study is the first reported detection of Bartonella spp. in R. rattus and R. norvegicus from the Sahiwal area of Punjab, Pakistan.
Subject(s)
Bartonella Infections , Bartonella , Rats , Animals , Humans , Bartonella/genetics , Bartonella Infections/epidemiology , Bartonella Infections/veterinary , Pakistan/epidemiology , Phylogeny , Molecular Epidemiology , Mammals , RodentiaABSTRACT
BACKGROUND: Animal husbandry practices in different livestock production systems and increased livestock-wildlife interactions are thought to be primary drivers of antimicrobial resistance (AMR) in Arid and Semi-Arid Lands (ASALs). Despite a tenfold increase in the camel population within the last decade, paired with widespread use of camel products, there is a lack of comprehensive information concerning beta-lactamase-producing Escherichia coli (E. coli) within these production systems. OBJECTIVES: Our study sought to establish an AMR profile and to identify and characterise emerging beta-lactamase-producing E. coli isolated from faecal samples obtained from camel herds in Northern Kenya. METHODS: The antimicrobial susceptibility profiles of E. coli isolates were established using the disk diffusion method, with beta-lactamase (bla) gene PCR product sequencing performed for phylogenetic grouping and genetic diversity assessments. RESULTS: Here we show, among the recovered E. coli isolates (n = 123), the highest level of resistance was observed for cefaclor at 28.5% of isolates, followed by cefotaxime at 16.3% and ampicillin at 9.7%. Moreover, extended-spectrum beta-lactamase (ESBL)-producing E. coli harbouring the blaCTX-M-15 or blaCTX-M-27 genes were detected in 3.3% of total samples, and are associated with phylogenetic groups B1, B2 and D. Multiple variants of non-ESBL blaTEM genes were detected, the majority of which were the blaTEM-1 and blaTEM-116 genes. CONCLUSIONS: Findings from this study shed light on the increased occurrence of ESBL- and non-ESBL-encoding gene variants in E. coli isolates with demonstrated multidrug resistant phenotypes. This study highlights the need for an expanded One Health approach to understanding AMR transmission dynamics, drivers of AMR development, and appropriate practices for antimicrobial stewardship in camel production systems within ASALs.
Subject(s)
Escherichia coli Infections , Escherichia coli , Animals , Escherichia coli/genetics , beta-Lactamases/genetics , Anti-Bacterial Agents/pharmacology , Camelus , Escherichia coli Infections/epidemiology , Escherichia coli Infections/veterinary , Phylogeny , Kenya/epidemiology , Drug Resistance, Bacterial/geneticsABSTRACT
Ticks and tick-borne diseases represent major threats to the public health of the Mongolian population, of which an estimated 26% live a traditional nomadic pastoralist lifestyle that puts them at increased risk for exposure. Ticks were collected by dragging and removal from livestock in Khentii, Selenge, Tuv, and Umnugovi aimags (provinces) during March-May 2020. Using next-generation sequencing (NGS) with confirmatory PCR and DNA sequencing, we sought to characterize the microbial species present in Dermacentor nuttalli (n = 98), Hyalomma asiaticum (n = 38), and Ixodes persulcatus (n = 72) tick pools. Rickettsia spp. were detected in 90.4% of tick pools, with Khentii, Selenge, and Tuv tick pools all having 100% pool positivity. Coxiella spp. were detected at an overall pool positivity rate of 60%, while Francisella spp. were detected in 20% of pools and Borrelia spp. detected in 13% of pools. Additional confirmatory testing for Rickettsia-positive pools demonstrated Rickettsia raoultii (n = 105), Candidatus Rickettsia tarasevichiae (n = 65) and R. slovaca/R. sibirica (n = 2), as well as the first report of Candidatus Rickettsia jingxinensis (n = 1) in Mongolia. For Coxiella spp. reads, most samples were identified as a Coxiella endosymbiont (n = 117), although Coxiella burnetii was detected in eight pools collected in Umnugovi. Borrelia species that were identified include Borrelia burgdorferi sensu lato (n = 3), B. garinii (n = 2), B. miyamotoi (n = 16), and B. afzelii (n = 3). All Francisella spp. reads were identified as Francisella endosymbiont species. Our findings emphasize the utility of NGS to provide baseline data across multiple tick-borne pathogen groups, which in turn can be used to inform health policy, determine regions for expanded surveillance, and guide risk mitigation strategies.
Subject(s)
Borrelia , Dermacentor , Francisella , Ixodes , Ixodidae , Animals , Ixodes/microbiology , Dermacentor/microbiology , Mongolia , High-Throughput Nucleotide Sequencing , Ixodidae/microbiology , Borrelia/genetics , Francisella/geneticsABSTRACT
Rickettsia microorganisms are causative agents of several neglected emerging infectious diseases in humans transmitted by arthropods including ticks. In this study, ticks were collected from four geographical regions of Uganda and pooled in sizes of 1-179 ticks based on location, tick species, life stage, host, and time of collection. Then, they were tested by real-time PCR for Rickettsia species with primers targeting gltA, 17kDa and ompA genes, followed by Sanger sequencing of the 17kDa and ompA genes. Of the 471 tick pools tested, 116 (24.6%) were positive for Rickettsia spp. by the gltA primers. The prevalence of Rickettsia varied by district with Gulu recording the highest (30.1%) followed by Luwero (28.1%) and Kasese had the lowest (14%). Tick pools from livestock (cattle, goats, sheep, and pigs) had the highest positivity rate, 26.9%, followed by vegetation, 23.1%, and pets (dogs and cats), 19.7%. Of 116 gltA-positive tick pools, 86 pools were positive using 17kDa primers of which 48 purified PCR products were successfully sequenced. The predominant Rickettsia spp. identified was R. africae (n = 15) in four tick species, followed by R. conorii (n = 5) in three tick species (Haemaphysalis elliptica, Rhipicephalus appendiculatus, and Rh. decoloratus). Rickettsia conorii subsp. israelensis was detected in one tick pool. These findings indicate that multiple Rickettsia spp. capable of causing human illness are circulating in the four diverse geographical regions of Uganda including new strains previously known to occur in the Mediterranean region. Physicians should be informed about Rickettsia spp. as potential causes of acute febrile illnesses in these regions. Continued and expanded surveillance is essential to further identify and locate potential hotspots with Rickettsia spp. of concern.
Subject(s)
Cat Diseases , Dog Diseases , Ixodidae , Rhipicephalus , Rickettsia , Spotted Fever Group Rickettsiosis , Animals , Cattle , Humans , Dogs , Sheep , Cats , Swine , Uganda/epidemiology , Israel , Rickettsia/genetics , Ixodidae/microbiology , Spotted Fever Group Rickettsiosis/epidemiology , Rhipicephalus/genetics , Real-Time Polymerase Chain Reaction/veterinary , GoatsABSTRACT
Outer surface protein C (OspC) is a commonly used marker in population studies of Borreliella to differentiate types and establish evolution over time. Investigating the ospC genetic types of Borreliella burgdorferi across multiple organ tissues of white-footed mice has the potential to contribute to our understanding of Lyme disease and the wide spectrum of clinical presentation associated with infection. In this study, five unique tissue types were sampled from 90 mice and screened for B. burgdorferi infections. This initial screening revealed a 63% overall B. burgdorferi infection rate in the mice collected (57/90). A total of 163 tissues (30.4%) tested positive for B. burgdorferi infections and when mapped to Borreliella types, 143,894 of the initial 322,480 reads mapped to 10 of the reference sequences in the ospC strain library constructed for this study at a 97% MOI. Two tissue types, the ear and the tongue, each accounted for 90% of the observed Borreliella sequence diversity in the tissue samples surveyed. The largest amount of variation was observed in an individual ear tissue sample with six ospC sequence types, which is equivalent to 60% of the observed variation seen across all tested specimens, with statistically significant associations observed between tissue type and detected Borreliella. There is strong evidence for genetic variability in B. burgdorferi within local white-footed mouse populations and even within individual hosts by tissue type. These findings may shed light on drivers of infection sequalae in specific tissues in humans and highlights the need for expanded surveillance on the epigenetics of B. burgdorferi across reservoirs, ticks, and infected patients.