Parasite Counts Research Articles

Fitness Costs of Parasites Explain Multiple Life-History Trade-Offs in a Wild Mammal.

AbstractReproduction in wild animals can divert limited resources away from immune defense, resulting in increased parasite burdens. A long-standing prediction of life-history theory states that these parasites can harm the reproductive individual, reducing its subsequent survival and fecundity, producing reproduction-fitness trade-offs. Here, we examined associations among reproductive allocation, immunity, parasitism, and subsequent survival and fecundity in a wild population of individually identified red deer (Cervus elaphus). Using path analysis, we investigated whether costs of lactation in terms of downstream survival and fecundity were mediated by changes in strongyle nematode count and mucosal antibody levels. Lactating females exhibited increased parasite counts, which were in turn associated with substantially decreased fitness in the following year in terms of overwinter survival, fecundity, subsequent calf weight, and parturition date. This study offers observational evidence for parasite regulation of multiple life-history trade-offs, supporting the role of parasites as an important mediating factor in wild mammal populations.

Liver and kidney dysfunction, hypoglycemia, and thrombocytopenia in Plasmodium vivax malaria patients at a Colombian Northwest region

Plasmodium vivax has high morbidity, it is the Plasmodium species with the greatest worldwide distribution, and its ability to trigger severe symptoms is currently recognized. The present study aims to compare the clinical and epidemiological characteristics of patients with P. vivax malaria, with and without complication criteria, in an endemic area for malaria transmission in northwest Colombia. A descriptive cross-sectional study was carried out between 2017 and 2019, patients with P.vivax severe malaria (n = 50), non-severe malaria (n = 56) and healthy controls (n = 50) were included. Sociodemographic, clinical, hematological, and biochemical characteristics were analyzed. Clinical follow-up was carried out in a group of patients with severe malaria. The statistical analysis was carried out in GraphPad Prism; the Chi-square test analyzed categorical variables, comparisons of variables for the three groups were carried out by the Kruskal-Wallis test and comparison between two groups by the Mann-Whitney test. A multiple correspondence analysis described the relationship between variables, which was carried out through the R software. One hundred fifty-six individuals were linked to the study, 76 women and 80 men, between 3 and 71 years old. For 50% of the patients, it was their first malaria episode; 42% of the patients classified with severe malaria required hospitalization, compared to 7.1% of the patients with non-severe malaria. Parasitaemia was similar in both clinical groups; however, 10% of severe patients presented high parasitemia, between 20,000-135,000. The most frequent clinical characteristics in patients with severe malaria were severe thrombocytopenia in 54%, hypoglycemia in 48%, and liver and kidney failure in 30%. Biochemical and hematological parameters returned to normal in 90% of the patients with severe malaria on the third day after starting treatment. Thrombocytopenia, hypoglycemia, and liver and kidney dysfunctions were the most frequent P. vivax malaria complications in this study. Hemoglobin concentration and parasite count were not related to the clinical condition of patients. Thrombocytopenia was the most frequent finding in patients with malaria, and its severity presented an inverse relationship with the number of previous malaria episodes.

A preliminary assessment of indirect impacts on aquaculture species health and welfare in Scotland during COVID-19 lockdown.

COVID-19 led to sudden changes in human activities, mainly due to restrictive measures required to supress the virus. We assess the preliminary evidence for impacts on animal health and welfare in Scottish aquaculture, a key economic activity in remoter areas of the country. We summarise the industry structure, explore pathways of vulnerability to aquatic animal disease within a One Health framework that may be accentuated by impacts of COVID-19, and use basic routine data collection on the key welfare indicators of salmon mortality and parasitic sea lice counts. The indicators were published on schedule and provide no evidence of gross impact on health and welfare, at least for salmon, during the period of intensive lockdown restrictions in Scotland. Longer term effects cannot be ruled out and we do not assess impacts on the economic or social aspects of aquaculture production.

Modulation of IMD, Toll, and Jak/STAT Immune Pathways Genes in the Fat Body of Rhodnius prolixus During Trypanosoma rangeli Infection.

Trypanosoma rangeli is the second most common American trypanosome that infects man. It is vectored by triatomines from the genus Rhodnius, in which it invades the hemolymph and infects the salivary glands, avoiding the bug immune responses. In insects, these responses are initiated by well conserved pathways, mainly the IMD, Toll, and Jak/STAT. We hypothesize that long-term infection with T. rangeli in the gut or hemolymph of Rhodnius prolixus triggers different systemic immune responses, which influence the number of parasites that survive inside the vector. Thus, we investigated groups of insects with infections in the gut and/or hemolymph, and evaluated the parasite load and the expression in the fat body of transcription factors (Rp-Relish, Rp-Dorsal, and Rp-STAT) and inhibitors (Rp-Cactus and Rp-Caspar) of the IMD, Toll, and Jak/STAT pathways. We detected lower parasite counts in the gut of insects without hemolymph infection, compared to hemolymph-infected groups. Besides, we measured higher parasite numbers in the gut of bugs that were first inoculated with T. rangeli and then fed on infected mice, compared with control insects, indicating that hemolymph infection increases parasite numbers in the gut. Interestingly, we observed that genes from the three immune pathways where differentially modulated, depending on the region parasites were present, as we found (1) Rp-Relish downregulated in gut-and/or-hemolymph-infected insects, compared with controls; (2) Rp-Cactus upregulated in gut-infected insect, compared with controls and gut-and-hemolymph-infected groups; and (3) Rp-STAT downregulated in all groups of hemolymph-infected insects. Finally, we uncovered negative correlations between parasite loads in the gut and Rp-Relish and Rp-Cactus expression, and between parasite counts in the hemolymph and Rp-Relish levels, suggesting an association between parasite numbers and the IMD and Toll pathways. Overall, our findings reveal new players in R. prolixus–T. rangeli interactions that could be key for the capacity of the bug to transmit the pathogen.

Mobile-Aware Deep Learning Algorithms for Malaria Parasites and White Blood Cells Localization in Thick Blood Smears

Effective determination of malaria parasitemia is paramount in aiding clinicians to accurately estimate the severity of malaria and guide the response for quality treatment. Microscopy by thick smear blood films is the conventional method for malaria parasitemia determination. Despite its edge over other existing methods of malaria parasitemia determination, it has been critiqued for being laborious, time consuming and equally requires expert knowledge for an efficient manual quantification of the parasitemia. This pauses a big challenge to most low developing countries as they are not only highly endemic but equally low resourced in terms of technical personnel in medical laboratories This study presents an end-to-end deep learning approach to automate the localization and count of P.falciparum parasites and White Blood Cells (WBCs) for effective parasitemia determination. The method involved building computer vision models on a dataset of annotated thick blood smear images. These computer vision models were built based on pre-trained deep learning models including Faster Regional Convolutional Neural Network (Faster R-CNN) and Single Shot Multibox Detector (SSD) models that help process the obtained digital images. To improve model performance due to a limited dataset, data augmentation was applied. Results from the evaluation of our approach showed that it reliably detected and returned a count of parasites and WBCs with good precision and recall. A strong correlation was observed between our model-generated counts and the manual counts done by microscopy experts (posting a spear man correlation of ρ = 0.998 for parasites and ρ = 0.987 for WBCs). Additionally, our proposed SSD model was quantized and deployed on a mobile smartphone-based inference app to detect malaria parasites and WBCs in situ. Our proposed method can be applied to support malaria diagnostics in settings with few trained Microscopy Experts yet constrained with large volume of patients to diagnose.

Health status evaluation of striped bass ( Morone saxatilis ) exposed to low temperature in sea cage culture during the grow‐out

Striped bass (Morone saxatilis) is a species with high production potential for human consumption. However, like any other cultured species, they are prone to be exposed to adverse climate conditions, compromising their health status until a certain degree compromises the success of reaching commercial size. It is proposed that haematological parameters testing during the whole growing out season represents a useful tool to assess the overall fish health status. Information on M. saxatilis haematology is limited. Therefore, the present study aimed was to provide the haematological and blood chemistry values for commercial striped bass grow-out. Fish from three different group sizes and under low sub-optimal temperature (16 to 18°C) were sampled in correlation to copepods (Peniculus sp.) present attached to the fins. Thirty fish from each group (sized 0.17, 0.54 and 1.17 kg, corresponding to different ages and batches) were all sampled (blood and external parasites count) during the spring (5 June, June 12 and June 16, 2019). The results show that differences in blood parameters were only observed according to the weight of striped bass such as the haematocrit (HCT), haemoglobin, mean corpuscular haemoglobin concentration (MCHC), white blood cells (WBC) count, total protein, globulin, ratio A/G, cholesterol, triglycerides and glucose. In contrast, the copepods present showed a preference for the caudal fin of the striped bass, followed by the first dorsal and pectoral fin. The smaller fish (0.179 kg) were the most susceptible to Peniculus sp., compared to the largest fish (1.174 kg). So far, it can be concluded that at this stage, the copepod does not show any adverse effect on the fish health since the condition factor and blood parameters were statistically similar along with the different copepod infestation levels (intensity ranged from 7 to 109). However, this new copepod, here registered for the first time in the Morone saxatilis, was registered during the sunset to increase environmental temperature. Even if no signs of a harmful relationship between parasites between young and old organisms, it will be necessary to be further monitored. The copepod incidence and the blood parameters should be analysed along the year (different temperatures), aiming to detect any correlation to the copepods present or, in any case, the overall health status or another parasite present under the seabass culture conditions.

Long term surveillance reveals nematode Elaphostrongylus cervi as a practical indicator of red deer management

Measures of performance in wild ungulates must consider density dependent and stochastic factors such as parasitic rates (as natural enemies in intimae relation with hosts) along with the impact of population management. In order to standardize parasite counts to be useful ecological indicators, it is essential to test host and parasite responses to the abovementioned. In the Iberian Peninsula, the parasitic nematode Elaphostrongylus cervi and its host the red deer (Cervus elaphus) provide an excellent practical scenario to illustrate how parasitic rates should be interpreted under different management contexts. Our study focuses on two distinct management scenarios, one deer population (LM) with supplemental feeding and one population (QM) with almost no human intervention, aside from hunting. We aim to assess how management (supplemental feeding) modulates the relationships of density dependent, stochastic and individual factors, and E. cervi faecal larvae counts in the red deer, so as with other physiological traits (body condition and spleen weight - as a proxy to immunological status). Overall, we have shown the decisive role that density and precipitation can have in a Mediterranean environment, with different trends in the two studied areas (e.g. negative correlation between E. cervi and red deer density in supplemented population, in opposition to un-supplemented). The crucial role that precipitation combined with density can have on deer dynamics, along with the artificial feeding as buffer of some traits, reinforces the need for an adaptive management, and the demand to manage each population considering the surrounding environment. Management strategies selected in each site can establish populations dynamics and health and should be closely monitored in a long-term context, as it occurs in our study.

Malaria Severity Score in Malaria Patients Admitted in Critical Care Wards

Introduction: Prognostic scoring system in Intensive Care Unit (ICU) can be generic, which can be applied to any critical illness for which patients are admitted in critical wards or can be disease specific. Malaria Severity Score (MSS) is a disease specific prognostic scoring system. Aim: To study the role of MSS in patients having malaria who were critically ill having multi organ dysfunction and to correlate the score with risk of mortality. Materials and Methods: This longitudinal study was conducted at the Department of General Medicine, SBKSMI & RC, Sumandeep Vidyapeeth, Vadodara, Gujarat, India. Adult patients (>18 years) with falciparum as well as vivax malaria, who had positive peripheral smear malaria and were admitted in ICU/Casualty (Emergency) ward, were taken in the study. The score was calculated on day of admission, day 2 and day 7. The score was analysed between two groups: survivors and non-survivors. Appropriate statistical tests were applied (z-test for two population proportion and Chi-square test for categorical values). The p-value <0.05 was considered as significant. Results: Out of 60 patients, 41 survived and 19 died due to malaria. Mean age of survivors was 38.56±2.27 and of non-survivors 40.21±5.6 years (p=0.718). There were 27 patients of P.vivax, 30 of P. falciparum and three patients of mixed infection; mortality was in 09, 08, 02 patients, respectively. On admission, out of total 60 patients, 10 (16.67%) had 1+, 20 (33.33%) had 2+, 24 (40%) had 3+ and 6 (10%) had 4+ parasite count. There were no patients in 1+ parasite count group, two (10%) in 2+, eleven (45.8%) in 3+ and six (100%) in 4+ parasite count group. Mean MSS was not significantly different on day 0 and day 2 but was higher on day 7 in non-survivor group than in survivors group (p=0.005). Mortality prediction score cut-off was ≥9, which was obtained by plotting Receiver Operating Characteristic (ROC) curve. Mean MSS in non-survivor group was 7.37 on day 0, 6.58 on day 2 and 9.11 on day 7. Thus, MSS score of day 7 gave `prediction reaching cut-off value of ≥9. Conclusion: MSS was found to be a useful prognostic score in severe falciparum/vivax malaria who needs intensive care treatment as sequential score gives significant difference in survivors and non-survivors on seventh day.

Thymus vulgaris, Mentha piperita and Elettaria cardamomum against Trypanosoma evansi in vitro and in an animal model with new insights for the treatment of trypanosomosis.

Trypanosomosis is a worldwide disease that affects human and livestock populations with limited availability and high cost of trypanocides. The study aims to evaluate the possible in vitro and in vivo anti-trypanosomal activity of Thymus vulgaris (thyme), Mentha piperita (mint) and Elettaria cardamomum (cardamom) aqueous extracts against Trypanosoma evansi in experimentally infected rats using Intropar as a reference drug. The crude extracts of the selected plants were used in three concentrations (2500, 2000, and 1000 μg/ml). The in vitro trypanocidal activities were assessed regarding parasite motility, count, and infectivity. The in vivo susceptibility of T. evansi was evaluated by assessing the level of parasitemia in the experimental rats. The packed cell volume (PCV) was also monitored. Both the in vitro and in vivo experiments showed trypanocidal activity, of all the tested extracts, higher than that of Intropar. The in vitro trypanocidal effects were dose-dependent and represented by a significant reduction of the parasite count together with immobilizing effect within 3 hours incubation period, compared to the negative and positive controls (p< 0.05). The in vivo trypanocidal effects of the different concentrations of all the tested extracts were represented by the significantly lowered levels of parasitemia, compared to the negative control (NC) group with varying degrees; in a dose-dependent manner concerning the time. They exhibited also a significantly higher level in PCV recovery compared to the NC group (p < 0.05). This study initially confirmed the potent in vitro and in vivo trypanocidal effect of the three extracts, with a potentially promising future for the treatment of trypanosomosis.

Efficacy of a novel topical combination of esafoxolaner, eprinomectin and praziquantel for the prevention of heartworm disease in cats.

NexGard® Combo is a novel topical endectoparasiticide formulation for cats combining the insecticide/acaricide esafoxolaner, the nematodicide eprinomectin and the cestodicide praziquantel. The efficacy of this novel formulation for the prevention of heartworm disease in cats was tested in two experimental studies using an induced infection model and a randomized, blinded, placebo-controlled study design, and two USA isolates of Dirofilaria immitis. In each study, 20 naïve cats were each inoculated sub-cutaneously with 100 third-stage larvae of D. immitis 30 days before treatment. Following randomization to two treatment groups of ten cats, each cat was treated topically once, either with the minimum recommended dose of the novel formulation, or with an identical volume of placebo. Five months after treatment (6 months after infections), the cats were humanely euthanized for parasite recovery and count. Efficacy was calculated by comparison of the numbers of adult D. immitis recovered in the control and in the novel formulation groups. In the control groups of each study, D. immitis were recovered in seven and nine cats (respective worm counts ranges 1–7 and 1–16, respective geometric means 1.6 and 5.1). In both studies, none of the treated cats harbored any D. immitis at necropsy and the calculated efficacy of the novel formulation was 100%. There were no adverse reactions related to treatment with the novel formulation. The results of these two studies demonstrate that a topical NexGard® Combo application at the minimum label dose is well-tolerated and efficacious in preventing heartworm disease in cats.

Efficacy of a novel topical combination of esafoxolaner, eprinomectin and praziquantel against Echinococcus multilocularis infections in cats.

NexGard® Combo, a novel topical endectoparasiticide formulation for cats combining esafoxolaner, eprinomectin and praziquantel, for the treatment of internal and external parasite infestations, including arthropods, nematodes and cestodes, was tested for efficacy against induced infections of Echinococcus multilocularis in cats, in two experimental studies. The two studies were performed in the United States with the same E. multilocularis isolate sourced locally. In each study, 20 cats were inoculated intra-gastrically with ~30,000 E. multilocularis protoscoleces three weeks before treatment, then ten cats were randomly allocated to a placebo control group or to the novel formulation treated group. Inoculated cats were treated topically once at the minimum recommended dose of the novel formulation, or with an identical volume of placebo. One week after treatment, cats were humanely euthanized for parasite recovery and count. The efficacy calculation was based on comparison of number of scoleces found in the control group and the novel formulation group. In the two control groups, E. multilocularis scoleces were found in five (range: 30–1025) and eight (range 2–345) cats, the geometric means inclusive of the ten cats per group were 8.9 and 28.8, respectively. In the two novel formulation-treated groups, none of the cats harbored any E. multilocularis scoleces, demonstrating 100% efficacy.

Efficacy of a novel topical combination of esafoxolaner, eprinomectin and praziquantel in cats against Toxocara cati and Dipylidium caninum.

NexGard® Combo, a novel topical antiparasitic product for cats, combines the insecticide/acaricide esafoxolaner with the nematocide eprinomectin and cestodicide praziquantel. The efficacy of this combination product was evaluated against two common endoparasites of global occurrence in cats, the nematode Toxocara cati and the cestode Dipylidium caninum, in five controlled studies using naturally or experimentally infected cats with parasites of North American, South African or European origin. Cats evaluated in these studies harbored patent infection of the target parasite confirmed through a pre-treatment fecal examination. In each study, cats were allocated randomly to two groups of equal size (8 or 10 cats per group per study), one group treated with a placebo (mineral oil) and the other with NexGard® Combo. Both treatments were administered once as a spot-on at 0.12 mL per kg body weight to deliver the minimum label dosage (1.44 mg/kg esafoxolaner, 0.48 mg/kg eprinomectin, and 10.0 mg/kg praziquantel) to the NexGard® Combo-treated cats. To determine efficacy, geometric mean parasite counts seven to 12 days after treatment of placebo-treated (control) cats and NexGard® Combo-treated cats were compared. The efficacy of NexGard® Combo was 98.8% and 100% against adult T. cati in two studies; and 98.0%, 98.3% and 93.2% against D. caninum in three studies. No adverse events related to treatment were observed throughout the studies. These studies demonstrate high efficacy against these major feline endoparasites and excellent acceptability of the novel topical antiparasitic combination of esafoxolaner, eprinomectin and praziquantel.

Knowlesi malaria: Human risk factors, clinical spectrum, and pathophysiology.

Plasmodium knowlesi is endemic across Southeast Asia, and is the commonest cause of zoonotic malaria. The spectrum of clinical disease from P. knowlesi infection ranges from asymptomatic infection, through to severe malaria and death. Over 90% of clinical disease occurs in adults, mostly living in forest edge areas undergoing intensive land use change. With a 24-h asexual life cycle in humans, high parasite counts are possible, but most clinical cases of knowlesi malaria are uncomplicated with low parasitaemia. In co-endemic areas, median parasitaemia in knowlesi malaria is lower than that seen in vivax and falciparum malaria, suggesting a lower fever threshold. Severe malaria occurs in 6-9% of symptomatic adults. Manifestations of severe malaria from P. knowlesi are similar to those seen with falciparum malaria, with the notable absence of coma. Age, parasitaemia, cardiovascular comorbidities and delayed diagnosis are risk factors for severe disease and death, which are only seen in adults. Thrombocytopenia is near-universal in adults, likely related to platelet-red cell binding and clearance. Mechanisms underlying the microvascular sludging seen in fatal disease in non-natural primate hosts and the microvascular accumulation of parasites in fatal human disease are not clear. Marked reductions in deformability of both infected and uninfected red blood cells are associated with disease severity in both humans and other non-natural primate hosts, likely contributing to impaired microvascular perfusion and organ dysfunction. Endothelial activation, endothelial dysfunction, glycocalyx degradation and haemolysis are also associated with, and likely contribute to, severe disease and organ dysfunction, particularly acute kidney injury.

High Prevalence of Low-Level Parasitemia With Plasmodium vivax in Makira-Ulawa Province Presents a Challenge for the Diagnosis and Eradication of Malaria in Solomon Islands.

Background: Malaria remains endemic in Solomon Islands, but data on malaria in the provinces of Solomon Islands are limited. This study from Makira-Ulawa Province aimed to identify the most prevalent strain of malaria and assess if the available rapid diagnostic test (RDT) was effective in Kirakira Hospital.Methods: Forty-five patients who presented to Kirakira Hospital with symptoms of fever had a positive malaria parasite smear during a 4-week period in 2017. The parasite count for each smear was calculated. Simultaneous testing using the CareStart Malaria HRP2/pLDH (Pf/pan) Combo RDT was conducted. The data for all malaria parasite smears performed in Makira-Ulawa Province in 2016 were collated for comparison.Results: All 45 patients diagnosed with malaria in a 4-week period in 2017 were positive for Plasmodium vivax. The median parasite load was 280 parasites per μL (range, 160 to 640 parasites per μL). None of the 45 CareStart RDTs performed was positive. In 2016, 5,505 of 17,195 patients (32.0%) screened had malaria parasites detected on a malaria parasite smear. P vivax was detected in 5,212 (94.7%) and Plasmodium falciparum in 285 (5.2%) of patients with malaria.Conclusion: P vivax is the predominant strain of malaria present in Makira-Ulawa Province. RDTs were not helpful in the diagnosis of malaria at Kirakira Hospital. The parasite load detected in the 45 patients diagnosed with malaria in this study was low. A focus on attempting to eradicate P vivax in the community through improved compliance with treatment protocols is suggested as a possible way forward to best manage malaria in Makira-Ulawa Province.

Genetic Variation, GWAS and Accuracy of Prediction for Host Resistance to Sparicotyle chrysophrii in Farmed Gilthead Sea Bream (Sparus aurata).

Gilthead sea bream (Sparus aurata) belongs to a group of teleost which has high importance in Mediterranean aquaculture industry. However, industrial production is increasingly compromised by an elevated outbreak of diseases in sea cages, especially a disease caused by monogeneans parasite Sparicotyle chrysophrii. This parasite mainly colonizes gill tissues of host and causes considerable economical losses with mortality and reduction in growth. The aim of current study was to explore the genetics of host resistance against S. chrysophrii and investigate the potential for genomic selection to possibly accelerate genetic progress. To achieve the desired goals, a test population derived from the breeding nucleus of Andromeda Group was produced. This experimental population was established by crossing of parents mated in partial factorial crosses of ∼8 × 8 using 58 sires and 62 dams. The progeny obtained from this mating design was challenged with S. chrysophrii using a controllable cohabitation infection model. At the end of the challenge, fish were recorded for parasite count, and all the recorded fish were tissue sampled for genotyping by sequencing using 2b-RAD methodology. The initial (before challenge test) and the final body weight (after challenge test) of the fish were also recorded. The results obtained through the analysis of phenotypic records (n = 615) and the genotypic data (n = 841, 724 offspring and 117 parents) revealed that the resistance against this parasite is lowly heritable (h2 = 0.147 with pedigree and 0.137 with genomic information). We observed moderately favorable genetic correlation (Rg = −0.549 to −0.807) between production traits (i.e., body weight and specific growth rate) and parasite count, which signals a possibility of indirect selection. A locus at linkage group 17 was identified that surpassed chromosome-wide Bonferroni threshold which explained 22.68% of the total genetic variance, and might be playing role in producing genetic variation. The accuracy of prediction was improved by 8% with genomic information compared to pedigree.

Determinants of Parasite Clearance Time among Plasmodium knowlesi Patients in Malaysia

Plasmodium (P.) knowlesi infection was only recently discovered in 2004, and since then the number of cases has increased each year. As such, there is still a need to understand the clinical management of P. knowlesi infection to ensure control of the disease. Therefore, this work was performed to determine factors that affect the clinical outcome of P. knowlesi infected patients. A cross-sectional study from 2012 to 2016 was conducted in Hospital Kuala Lipis, Pahang, Malaysia. The main clinical outcome was parasite clearance. A total of 72 P. knowlesi patients were included, which were mostly male (n=56, 77.80%), with a mean age of 37.39±14.61 years. Fifty-six patients (77.80%) were prescribed with artemisinin-based antimalarial following diagnosis, while the remaining patients (n=16, 22.20%) were treated with chloroquine. The length for parasite clearance of P. knowlesi was 4(4-5) days [(median (IQR)]. Factors that affect the primary outcome of the study (&gt;4 days for parasite clearance) was then determined. A multivariate logistic regression demonstrated that significant predictors of parasite clearance were initial parasite levels and number of symptoms (χ2=11.97, df(69), P=0.003). Those with an initial parasite count of &gt; 2 400/uL were 4.8 times more likely to take &gt; 4 days for parasite clearance (P=0.02). Having &lt; 4 symptoms increased the odds of &gt; 4 days for parasite clearance by 0.14 times (P=0.02). This study shows the need to closely monitor patients with higher initial parasite counts (&gt; 2400/uL) and patients with &gt; 4 symptoms associated with P. knowlesi infection, to ensure appropriate treatment is administered.

Inter-rater Variability in Malaria Microscopy at the LEKMA Hospital, Ghana.

Background Malaria remains a major cause of morbidity and mortality worldwide and particularly in sub-Saharan Africa where it is endemic. As such, it is important that a proper diagnosis is made before treatment is initiated. Malaria parasite count plays a key role in the diagnosis and management of malaria. Variations in ratings by laboratory personnel can impact negatively on the treatment regimen for malaria-infected patients. The study is thus aimed at evaluating and comparing the proficiency and parasitaemia counts by two different categories of laboratory staff at the LEKMA Hospital, Ghana. Materials and Methods A total of 200 confirmed malaria-positive samples were used in the study. Six thick and thin films were prepared from each sample and uniquely labelled. Two of the six slides were given to two WHO-accredited malaria microscopists to examine and report their respective parasite count/μl (parasite count/WBC × 8000). These were used as the reference for the two categories of laboratory staffs: rater A being diploma holders (Technical Officers referred to as untrained rater) and rater B being degree holders (Medical Laboratory Scientist referred to as trained rater) at the LEKMA Hospital. Results In comparison to the expected outcome, the parasite count by the rater group A (190 (151-239)]) and the rater group B (177 (140-224)) demonstrated significant positive correlation (r = 0.995, p < 0.0001 vs. r = 0.995, p < 0.0001, respectively) with the expected outcome in the cases of heavy parasitaemia. A statistically significant difference (p < 0.05) between counts by the different raters in low parasitemia was observed in this study. A persistent nosedive inter-rater agreement from k = 0.82 to k = 0.40 with increasing density cutoff was observed in this study. Conclusion The study observed that the degree of inter-rater agreement of parasite density count by various categories of laboratory personnel is almost perfect. However, the parasite count between raters varied significantly with very low levels of parasitemia but better correlated with heavy parasitemia.

Help or hindrance? The evolutionary impact of whole-genome duplication on immunogenetic diversity and parasite load.

Whole‐genome duplication (WGD) events occur in all kingdoms and have been hypothesized to promote adaptability. WGDs identified in the early history of vertebrates, teleosts, and angiosperms have been linked to the large‐scale diversification of these lineages. However, the mechanics and full outcomes of WGD regarding potential evolutionary impacts remain a topic of debate. The Corydoradinae are a diverse subfamily of Neotropical catfishes with over 170 species described and a history of WGDs. They are divided into nine mtDNA lineages, with species coexisting in sympatric—and often mimetic—communities containing representatives of two or more of the nine lineages. Given their similar life histories, coexisting species of Corydoras might be exposed to similar parasite loads and because of their different histories of WGD and genome size they provide a powerful system for investigating the impacts of WGD on immune diversity and function in an animal system. Here, we compared parasite counts and the diversity of the immune‐related toll‐like receptors (TLR) in two coexisting species of Corydoras catfish (C. maculifer and C. araguaiaensis), one diploid and one putative tetraploid. In the putative tetraploid C. araguaiaensis, we found significantly lower numbers of parasites and significantly higher diversity (measured by both synonymous and nonsynonymous SNP counts) in two TLR genes than in the diploid C. maculifer. These results provide insight into how WGD may impact evolution, in this case by providing greater immunogenetic diversity.

Revisiting the adequacy of infection criteria recommended in VICH GL 7 for anthelmintic effectiveness studies: Retrospective simulations

Studies conducted to support registration or approval of veterinary anthelmintics generally follow study design recommendations provided by the VICH (International Cooperation on Harmonisation of Technical Requirements for Registration of Veterinary Medicinal Products), “Efficacy of Anthelmintics: General Requirements” (VICH GL7). For dose confirmation studies, VICH GL7 provides recommendations for determining that the control animals had an adequate infection “to permit the appropriate standards of efficacy to be met with acceptable statistical and biological certitude/confidence.” In the simulation studies described in this report, we investigated the performance of one method, the statistical criterion given in Section 4.5 of VICH GL7, for evaluating the adequacy of infection in anthelmintic studies, in combination with the conventional criterion of a minimum of six adequately infected animals. We conducted numerical simulations, based on parasite data from previously conducted dose confirmation studies in dogs and cattle, to investigate how the statistical criterion impacts adequacy of infection determinations when used with the conventional criterion at various sample sizes. Simulation studies in common nematode species in both dogs and cattle indicated that under certain circumstances the statistical criterion can guard against overinterpreting the evaluation of adequacy of infection as sample size is increased. However, the statistical criterion may be overly restrictive for samples with adequate infection but containing multiple zero parasite counts and adding it to the conventional criterion does not provide any additional benefit when the sample contains no zero counts. It is important for investigators designing efficacy studies to understand the potential impact this criterion may have when establishing adequacy of infection criteria in study protocols.

Genomic selection for heterobothriosis resistance concurrent with body size in the tiger pufferfish, Takifugu rubripes

Parasite resistance traits in aquaculture species often have moderate heritability, indicating the potential for genetic improvements by selective breeding. However, parasite resistance is often synonymous with an undesirable negative correlation with body size. In this study, we first tested the feasibility of genomic selection (GS) on resistance to heterobothriosis, caused by the monogenean parasite Heterobothrium okamotoi, which leads to huge economic losses in aquaculture of the tiger pufferfish Takifugu rubripes. Then, using a simulation study, we tested the possibility of simultaneous improvement of parasite resistance, assessed by parasite counts on host fish (HC), and standard length (SL). Each trait showed moderate heritability (square-root transformed HC: h2 = 0.308 ± 0.123, S.E.; SL: h2 = 0.405 ± 0.131). The predictive abilities of genomic prediction among 12 models, including genomic Best Linear Unbiased Predictor (GBLUP), Bayesian regressions, and machine learning procedures, were also moderate for both transformed HC (0.248‒0.344) and SL (0.340‒0.481). These results confirmed the feasibility of GS for this trait. Although an undesirable genetic correlation was suggested between transformed HC and SL (rg = 0.228), the simulation study suggested the desired gains index can help achieve simultaneous genetic improvements in both traits.