Parasitological Contamination of Fresh Vegetables and Its Prevalence in Dessie Town, Northeast Ethiopia

Background: Consumption of vegetables and fruits is vital for health as they are good sources of carbohydrate, vitamins, minerals and fiber contents. On the other hand, vegetables and fruits are potential vehicles for the transmission of pathogenic parasites and protozoa that are transmitted through fecal-oral route. Objectives: The objective of this study was to assess the parasitic contamination of vegetable samples collected from farms, home gardens and street vendors in Dessie town. Material and Methods: A Cross-sectional study was conducted from April to June, 2014 to determine the level of parasitic contamination of vegetables and fruits sold in Dessie town. A total of 150 samples of different type of fruits and vegetables were washed with physiological saline, followed by vigorous hand shaking in a clean plastic bag for 15 minutes and then examined using sedimentation concentration technique. Parasites stages were identified based on WHO guideline. Results:Out of 150 vegetable samples collected, 95(63.4%) of the vegetables were contaminated with at least one parasite. E.histolytica/dispar (24%) was the most frequently detected parasite withG.lamblia cyst (1.33%) the least frequently detected one.The result also shows that therewas positive relation between types of vegetable and sites or sample area with p-value<0.000. Conclusions: The present study showed that there is a risk of acquiring parasitic infections from consumption of raw vegetables and fruits in Dessie town. Thus efforts should be made to aware the public and restaurant owners in particular to properly wash or disinfect raw vegetables before consumption. Keywords: Parasite, Contamination, vegetables, Dessie, Ethiopi

Naturally acquired antibodies to gametocyte antigens are associated with reduced transmission of Plasmodium vivax gametocytes to Anopheles arabiensis mosquitoes

Naturally acquired antibodies may reduce the transmission of Plasmodium gametocytes to mosquitoes. Here, we investigated associations between antibody prevalence and P. vivax infectivity to mosquitoes. A total of 368 microscopy confirmed P. vivax symptomatic patients were passively recruited from health centers in Ethiopia and supplemented with 56 observations from asymptomatic P. vivax parasite carriers. Direct membrane feeding assays (DMFA) were performed to assess mosquito infectivity; for selected feeds these experiments were also performed after replacing autologous plasma with malaria naïve control serum (n=61). The prevalence of antibodies against 6 sexual stage antigens (Pvs47, Pvs48/45, Pvs230, PvsHAP2, Pvs25 and PvCelTOS) and an array of asexual antigens was determined by ELISA and multiplexed bead-based assays. Gametocyte (ρ< 0.42; p = 0.0001) and parasite (ρ = 0.21; p = 0.0001) densities were positively associated with mosquito infection rates. Antibodies against Pvs47, Pvs230 and Pvs25 were associated with 23 and 34% reductions in mosquito infection rates (p<0.0001), respectively. Individuals who showed evidence of transmission blockade in serum-replacement DMFAs (n=8) were significantly more likely to have PvsHAP2 or Pvs47 antibodies. Further studies may demonstrate causality for the observed associations, improve our understanding of the natural transmission of P. vivax and support vaccine development

Comparison of infectivity of Plasmodium vivax to wild-caught and laboratory-adapted (colonized) Anopheles arabiensis mosquitoes in Ethiopia

BACKGROUND: Mosquito-feeding assays that assess transmission of Plasmodium from man-to-mosquito typically use laboratory mosquito colonies. The microbiome and genetic background of local mosquitoes may be different and influence Plasmodium transmission efficiency. In order to interpret transmission studies to the local epidemiology, it is therefore crucial to understand the relationship between infectivity in laboratory-adapted and local mosquitoes. METHODS: We assessed infectivity of Plasmodium vivax-infected patients from Adama, Ethiopia, using laboratory-adapted (colony) and wild-caught (wild) mosquitoes raised from larval collections in paired feeding experiments. Feeding assays used 4-6 day-old female Anopheles arabiensis mosquitoes after starvation for 12 h (colony) and 18 h (wild). Oocyst development was assessed microscopically 7 days post-feeding. Wild mosquitoes were identified morphologically and confirmed by genotyping. Asexual parasites and gametocytes were quantified in donor blood by microscopy. RESULTS: In 36 paired experiments (25 P. vivax infections and 11 co-infections with P. falciparum), feeding efficiency was higher in colony (median: 62.5%; interquartile range, IQR: 47.0-79.0%) compared to wild mosquitoes (median: 27.8%; IQR: 17.0-38.0%; Z = 5.02; P < 0.001). Plasmodium vivax from infectious individuals (51.6%, 16/31) infected a median of 55.0% (IQR: 6.7-85.7%; range: 5.5-96.7%; n = 14) of the colony and 52.7% (IQR: 20.0-80.0%; range: 3.2-95.0%; n = 14) of the wild mosquitoes. A strong association (ρ(16) = 0.819; P < 0.001) was observed between the proportion of infected wild and colony mosquitoes. A positive association was detected between microscopically detected gametocytes and the proportion of infected colony (ρ(31) = 0.452; P = 0.011) and wild (ρ(31) = 0.386; P = 0.032) mosquitoes. CONCLUSIONS: Infectivity assessments with colony and wild mosquitoes yielded similar infection results. This finding supports the use of colony mosquitoes for assessments of the infectious reservoir for malaria in this setting whilst acknowledging the importance of mosquito factors influencing sporogonic development of Plasmodium parasites

The epidemiology and detectability of asymptomatic plasmodium vivax and plasmodium falciparum infections in low, moderate and high transmission settings in Ethiopia

BACKGROUND: As countries move to malaria elimination, detecting and targeting asymptomatic malaria infections might be needed. Here, the epidemiology and detectability of asymptomatic Plasmodium falciparum and Plasmodium vivax infections were investigated in different transmission settings in Ethiopia. METHOD: A total of 1093 dried blood spot (DBS) samples were collected from afebrile and apparently healthy individuals across ten study sites in Ethiopia from 2016 to 2020. Of these, 862 were from community and 231 from school based cross-sectional surveys. Malaria infection status was determined by microscopy or rapid diagnostics tests (RDT) and 18S rRNA-based nested PCR (nPCR). The annual parasite index (API) was used to classify endemicity as low (API > 0 and < 5), moderate (API ≥ 5 and < 100) and high transmission (API ≥ 100) and detectability of infections was assessed in these settings. RESULTS: In community surveys, the overall prevalence of asymptomatic Plasmodium infections by microscopy/RDT, nPCR and all methods combined was 12.2% (105/860), 21.6% (183/846) and 24.1% (208/862), respectively. The proportion of nPCR positive infections that was detectable by microscopy/RDT was 48.7% (73/150) for P. falciparum and 4.6% (2/44) for P. vivax. Compared to low transmission settings, the likelihood of detecting infections by microscopy/RDT was increased in moderate (Adjusted odds ratio [AOR]: 3.4; 95% confidence interval [95% CI] 1.6-7.2, P = 0.002) and high endemic settings (AOR = 5.1; 95% CI 2.6-9.9, P < 0.001). After adjustment for site and correlation between observations from the same survey, the likelihood of detecting asymptomatic infections by microscopy/RDT (AOR per year increase = 0.95, 95% CI 0.9-1.0, P = 0.013) declined with age. CONCLUSIONS: Conventional diagnostics missed nearly half of the asymptomatic Plasmodium reservoir detected by nPCR. The detectability of infections was particularly low in older age groups and low transmission settings. These findings highlight the need for sensitive diagnostic tools to detect the entire parasite reservoir and potential infection transmitters

Prevalence of Plasmodium falciparum Pfcrt and Pfmdr1 alleles in settings with different levels of Plasmodium vivax co-endemicity in Ethiopia.

Plasmodium falciparum and P. vivax co-exist at different endemicity levels across Ethiopia. For over two decades Artemether-Lumefantrine (AL) is the first line treatment for uncomplicated P. falciparum, while chloroquine (CQ) is still used to treat P. vivax. It is currently unclear whether a shift from CQ to AL for P. falciparum treatment has implications for AL efficacy and results in a reversal of mutations in genes associated to CQ resistance, given the high co-endemicity of the two species and the continued availability of CQ for the treatment of P. vivax. This study thus assessed the prevalence of Pfcrt-K76T and Pfmdr1-N86Y point mutations in P. falciparum. 18S RNA gene based nested PCR confirmed P. falciparum samples (N?=?183) collected through community and health facility targeted cross-sectional surveys from settings with varying P. vivax and P. falciparum endemicity were used. The proportion of Plasmodium infections that were P. vivax was 62.2% in Adama, 41.4% in Babile, 30.0% in Benishangul-Gumuz to 6.9% in Gambella. The Pfcrt-76T mutant haplotype was observed more from samples with higher endemicity of P. vivax as being 98.4% (61/62), 100% (31/31), 65.2% (15/23) and 41.5% (22/53) in samples from Adama, Babile, Benishangul-Gumuz and Gambella, respectively. However, a relatively higher proportion of Pfmdr1-N86 allele (77.3-100%) were maintained in all sites. The observed high level of the mutant Pfcrt-76T allele in P. vivax co-endemic sites might require that utilization of CQ needs to be re-evaluated in settings co-endemic for the two species. A country-wide assessment is recommended to clarify the implication of the observed level of variation in drug resistance markers on the efficacy of AL-based treatment against uncomplicated P. falciparum malaria

Serological evidence for a decline in malaria transmission following major scale-up of control efforts in a setting selected for Plasmodium vivax and Plasmodium falciparum malaria elimination in Babile district, Oromia, Ethiopia.

BACKGROUND: Following successful malaria control during the last decade, Ethiopia instituted a stepwise malaria elimination strategy in selected low-transmission areas. METHODS: Cross-sectional surveys were conducted in Babile district, Oromia, Ethiopia from July to November 2017 to evaluate malaria infection status using microscopy and nested polymerase chain reaction (nPCR) and serological markers of exposure targeting Plasmodium falciparum and Plasmodium vivax apical membrane antigen-1 (AMA-1). RESULTS: Parasite prevalence was 1.2% (14/1135) and 5.1% (58/1143) for P. falciparum and 0.4% (5/1135) and 3.6% (41/1143) for P. vivax by microscopy and nPCR, respectively. Antibody prevalence was associated with current infection by nPCR for both P. falciparum (p<0.001) and P. vivax (p=0.014) and showed an age-dependent increase (p<0.001, for both species). Seroconversion curves indicated a decline in malaria exposure 15 y prior to sampling for P. falciparum and 11.5 y prior to sampling for P. vivax, broadly following malaria incidence data from district health offices, with higher antibody titres in adults than children for both species. CONCLUSIONS: Malaria transmission declined substantially in the region with continuing heterogeneous but measurable local transmission, arguing in favour of continued and tailored control efforts to accelerate the progress towards elimination efforts

<i>Anopheles stephensi</i> as an emerging malaria vector in the Horn of Africa with high susceptibility to Ethiopian <i>Plasmodium vivax</i> and <i>Plasmodium falciparum</i> isolates

AbstractAnopheles stephensi, an efficient Asian malaria vector, recently spread into the Horn of Africa and may increase malaria receptivity in African urban areas. We assessed occurrence, genetic complexity, blood meal source and infection status of An. stephensi in Awash Sebat Kilo town, Ethiopia. We used membrane feeding assays to assess competence of local An. stephensi to P. vivax and P. falciparum isolates from clinical patients. 75.3% of the examined waterbodies were infested with An. stephensi developmental stages that were genetically closely related to isolates from Djibouti and Pakistan. Both P. vivax and P. falciparum were detected in wild-caught adult An. stephensi. Local An. stephensi was more receptive to P. vivax compared to a colony of An. arabiensis. We conclude that An. stephensi is an established vector in this part of Ethiopia, highly permissive for local P. vivax and P. falciparum isolates and presents an important new challenge for malaria control.Summary of the articleAn. stephensi, a metropolitan malaria vector that recently expanded to the Horn of African, was highly susceptible to local P. falciparum and P. vivax isolates from Ethiopia and may increase malariogenic potential of rapidly expanding urban settings in Africa.</jats:sec

Investigating the association between household exposure to Anopheles stephensi and malaria in Sudan and Ethiopia: A case-control study protocol

Background Endemic African malaria vectors are poorly adapted to typical urban ecologies. However, Anopheles stephensi, an urban malaria vector formerly confined to South Asia and the Persian Gulf, was recently detected in Africa and may change the epidemiology of malaria across the continent. Little is known about the public health implications of An. stephensi in Africa. This study is designed to assess the relative importance of household exposure to An. stephensi and endemic malaria vectors for malaria risk in urban Sudan and Ethiopia. Methods Case-control studies will be conducted in 3 urban settings (2 in Sudan, 1 in Ethiopia) to assess the association between presence of An. stephensi in and around households and malaria. Cases, defined as individuals positive for Plasmodium falciparum and/or P. vivax by microscopy/rapid diagnostic test (RDT), and controls, defined as age-matched individuals negative for P. falciparum and/or P. vivax by microscopy/RDT, will be recruited from public health facilities. Both household surveys and entomological surveillance for adult and immature mosquitoes will be conducted at participant homes within 48 hours of enrolment. Adult and immature mosquitoes will be identified by polymerase chain reaction (PCR). Conditional logistic regression will be used to estimate the association between presence of An. stephensi and malaria status, adjusted for co-occurrence of other malaria vectors and participant gender. Conclusions Findings from this study will provide evidence of the relative importance of An. stephensi for malaria burden in urban African settings, shedding light on the need for future intervention planning and policy development

Age-related factors influencing the occurrence of undernutrition in northeastern Ethiopia

BACKGROUND: Undernutrition is a major public health problem on the globe particularly in the developing regions. The objective of the current study was to assess the prevalence of undernutrition in different age groups and examine the relationship of the disease to parasitic and socioeconomic factors among communities in Harbu Town, northeastern Ethiopia. METHODS: Stool samples of the study participants were examined for intestinal helminth infections using the Kato-Katz method. Blood specimens were diagnosed for Plasmodium infection using CareStartTM Malaria Pf/Pv Combo test. The blood type was determined from blood samples using antisera A and antisera B. In addition, the height and weight of the study participants was measured and information about their socioeconomic and sociodemographic characteristics was collected. RESULTS: Out of 484 individuals examined, 31.8% were undernourished and 32.0% were infected with intestinal helminths. The odds of undernutrition significantly decreased with an increase in the age of individuals. The prevalence of undernutrition in adults was significantly higher in males than in females and in those who had latrines than in those who did not have the facility. The odds of undernutrition in the 5 to 19 years age group was significantly higher in those who did not wash their hands before eating than in those who did. The prevalence of undernutrition in children younger than five years was significantly lower in those whose families were educated and had less than 5 family size compared to those with illiterate families and family size of greater than 5, respectively. However, the prevalence of undernutrition was similar in individuals who were infected and not infected with intestinal helminths. The intensity of Schistosoma mansoni infection was significantly higher among individuals of blood type A compared to those of type O. CONCLUSIONS: Prevalence of undernutrition was higher in children than in adults and the association of sex and socioeconomic factors with undernutrition showed variation with age. However, helminth infection was not related with undernutrition in all age groups