Knott Method Research Articles

Prevalence of infection with Dirofilaria immitis and Dirofilaria repens in dogs from the South-Eastern part of Romania

As a result of global warming, the change in the biological cycle of vectors and the increase in intercontinental travels, we are now facing an increase in the number of cases of vector-borne diseases. Among these, heartworm disease has escalated in recent years in Romania, with cases increasing in many parts of our country. Our study was carried out in the South-Eastern part of Romania, with the aim of establishing the prevalence of heartworm disease in dogs, with the identification of the two species Dirofilaria immitis and Dirofilaria repens. Blood samples were collected during the period May - July 2022 and January - July 2023, from 220 dogs with and without an owner from Tulcea county, from places such as Tulcea, Murighiol, Somova, Mineri, Niculițel. The blood samples were tested through the Knott method, which is considered as the reference method in the diagnosis of dirofilariosis in dogs. The results show a prevalence of Dirofilaria spp. infection of 11.36% in dogs. Of the 220 samples examined by the Knott test, 25 were positive for circulating microfilariae, of which 21 showed infestations with Dirofilaria immitis and 4 with co-infection with Dirofilaria immitis and Dirofilaria repens. The study underlines the importance of introducing monitoring and control programs for heartworm disease in dogs in Romania.

Use of adapted maternal strain in tilapia production (Oreochromis niloticus)

The world fish production has been growing in response to the great demand for healthy food and Brazil has the conditions to export fish. However, the development of the chain is necessary, with the use of production techniques and tested genetic material. Tilapia is an excellent breeder, however studies on specialized varieties need to be conducted. In view of the above, the present study aimed to evaluate the applicability of the MGTUFLAP variety as a matrix in diallel crossings with two commercial varieties widely spread in the territory and the performance of the offspring. Data from offspring originating from nine distinct genetic groups produced in the 2015/2016 aquaculture year were collected in the fish farming sector of the Federal University of Lavras. All animals were weighed and had their morphometry measured, then slaughtered and processed in order to obtain the weight of the cuts and processing residues. The general and specific combining ability and the maternal effect were estimated and the morphometric averages, cuts and yields were grouped using the Skott Knott method (p<0.05). In general, the genetic groups descending from MGTUFLAP variety showed worse performance for head size and filet weight, but obtained higher filet yield and lower carcass yield. The adapted variety showed good general and specific combining ability, as well as better maternal effect on the traits of head weight and filet yield. We conclude that the variety MGTUFLAP presents good results in crossbreeding and the females are an excellent option for maternal line.

Application of the Vegetation Condition Index in the Diagnosis of Spatiotemporal Distribution of Agricultural Droughts: A Case Study Concerning the State of Espírito Santo, Southeastern Brazil

We applied a robust framework for agricultural drought identification in the State of Espírito Santo, Brazil, by employing the Vegetation Condition Index (VCI) based on data obtained through the Enhanced Vegetation Index (EVI). By doing so, we analyzed the interrelationships between the VCI and anomalies in the Land Surface Temperature (LST), along with connections between the VCI and data considering water deficits in vulnerable areas. When it came to image processing, we focused on the use of analytics and GIS algorithms, while the Scott–Knott method elucidated the statistical analyses. Consequently, we identified drought areas followed by periods susceptible to their occurrence, indicating 2016 as the driest year. The North macroregion presented the lowest average values regarding VCI values in the most vulnerable periods, followed by the Central one. We also call attention to the highest LST averages observed in 2015 and 2016, as strong El Niño events marked the same timeframe periods. The methodological approach was efficient for the identification, analysis, and characterization of agricultural drought occurrences, enabling mitigation actions, as well as the management of the exploitation and protection of water resources. Moreover, further research should be conducted by incorporating other indices to enhance the understanding of agricultural drought and its effects on vegetation.

Refrigerated modified Knott concentrate enables long-term morphological viability of canine blood microfilariae

There are several methods of laboratory diagnosis of filarids, the most used are the thick smear and the Knott method. Both are quick to perform, have a low cost and allow observing the presence, quantifying and analyzing the morphological characteristics of microfilariae. Knowing the morphological viability of fixed microfilariae is of practical importance, as it allows the transport of samples to a laboratory, facilitates epidemiological studies , and allows the storage of samples for didactic. Thus, the aim of this study was to evaluate the morphological viability of microfilariae fixed in the refrigerated modified knott test using 2% formalin. To perform the modified Knott technique, 10 samples of microfilaremic dogs aged over 6 months were used. To evaluate the morphological viability time of the microfilariae in the modified Knott concentrate, the evaluations were repeated after intervals of 0, 1, 7, 30, 60, 120, 180, 240, and 304 days. In the present study, we did not verify any difference in the morphology of the microfilariae in any of the analyzed intervals from day 0 to 304 days, and it is possible to conclude that the use of 2% formalin in the modified Knott technique allows the microfilariae to be identified in a period of 304 days. days after processing the sample without changes in its morphology.

Occurrence of Dirofilaria immitis in Stray Dogs from Nepal

Nematodes of the genus Dirofilaria are widespread vector-borne helminths (VBH) of veterinary relevance. Dirofilariosis caused by D. immitis is frequently diagnosed in dogs often showing a severe clinical condition known as heartworm disease. Assessing the distribution pattern of canine dirofilariosis is pivotal to undertake appropriate control measures and define the risk of infection in animals and humans. This study provides original data on the occurrence of D. immitis in naive stray dogs from Nepal. An epidemiological study was performed on stray dogs from Siddharthanagar, Lumbini region, Nepal. Alive animals were blood sampled and examined for microfilariae using direct microscopy, buffy coat centrifugation and modified Knott's method. In addition, hematobiochemical parameters, including packed cell volume (PCV), alanine aminotransferase (SGPT), aspartate aminotransferase (SGOT), alkaline phosphate (ALP), creatinine, blood urea nitrogen (BUN), urea and total protein were analysed, along with a clinical scoring (body temperature and respiratory rate). During the observation period, data on autopsies performed on stray dogs showing canine heartworm disease were also included. The overall prevalence of D. immitis in both alive and necropsied dogs was 22.49% (38/169). Out of 150 alive dogs, 29 (19.3%) were positive for D. immitis microfilariae. The prevalence of the infection varied according to the technique used, ranging from 16.0 to 19.3% based on direct blood smear microscopy and modified Knott's technique, respectively. The infection rate was significantly higher (p < 0.05) in dogs aging more than 3years. A positive correlation was observed between SGPT and SGOT and the presence of microfilariae (p < 0.05). Among the 19 dead stray dogs, 9 animals showed adult D. immitis nematodes. Results of this survey account for the presence of D. immitis in stray dogs from Nepal, thus supporting the existence of a local transmission cycle of diroflariosis in the region. Further investigations are warranted to accurately define the prevalence of the infection in the canine population and to undertake appropriate control measures to reduce the burden on the infection in dogs and, accordingly, the risk of transmission to humans.

The Main Clinical Signs and Early Diagnosis of Canine Dirofilariosis in the Veterinary Practice of Farms in the Republic of Armenia

The purpose of the research is to determine the main clinical signs of dirofilariosis in dogs, taking into account the peculiarities of animal exploitation and to analyze the efficacy and convenience of using some diagnostic techniques. Materials and methods. The main clinical signs of dirofilariosis in dogs on the farms of Armenia have been studied. The presence of microfilariae was determined in native smears and using a modified Knott method. We also used the Asan Easy Test Heartworm and SNAP 4Dx Plus Test one-step cassette rapid tests for visual detection of Dirofilaria spp. antigen in blood serum. Results and discussion. 8.5% of dogs in the farms of the Republic of Armenia are infected with Dirofilaria sp. The most infected were dogs aged 5–8 years (75%). The main symptomatic signs of dirofilariosis in dogs were established in the specific conditions of the studied region and the specifics of the specific exploitation of animals. It has been established that the immunochromatographic test systems Asan Easy Test Heartworm and SNAP 4Dx Plus Test for visual detection of canine Dirofilaria spp. antigen in blood serum are the most effective for the diagnosis of dirofilariosis.

Seroepidemiological Study of Canine and Human Dirofilariasis in the Endemic Region of Northern Serbia.

Dirofilariasis is a vector-borne zoonotic disease caused mainly by Dirofilaria immitis and Dirofilaria repens that affect dogs and humans all over the world. Serbia is considered an endemic country to both forms of dirofilariasis, although most of the population is concentrated in the north of the country. The aims of this study were to show the prevalence of D. immitis and D. repens in dogs and the seroprevalence in humans compared to previous studies in Northern Serbia. In total, 346 dog sera samples and 265 human samples were analyzed. Dog blood samples were analyzed using the modified Knott's method to check whether there were Dirofilaria spp. microfilariae and serum samples were checked by a commercial D. immitis antigen test. Human serum samples were analyzed with a non-commercial ELISA for detection of specific anti-D. immitis, anti-D. repens, and anti-Wolbachia IgG antibodies, and confirmed by western blotting. The overall prevalence for Dirofilaria spp. in dogs was 29.19%. The overall prevalence for D. immitis was 26.30%. The percentages of D. immitis and D. repens microfilaremia in dogs were 25.72 and 1.45%, respectively, while D. immitis./D. repens microfilaremia co-infections were also 1.45%. The overall seroprevalence for Dirofilaria spp. in humans was 3.77%. The overall seroprevalence for D. immitis was 1.51, 1.13% for D. repens, and for D. immitis/D. repens co-infections was 1.13%. The results indicate that D. immitis and D. repens are present in dogs and humans in the province of Vojvodina, in the northern part of Serbia. It is most likely associated with the presence of many rivers, the climate, and presence of mosquitoes in the area, so there could be a real public health risk.

A cross sectional study on Dirofilaria immitis and Acanthocheilonema reconditum in sheepdogs in a western region in Iran.

Iran is one of the endemic areas of Dirofilariasis, and also one of the most important zoonotic infections. Dirofilaria immitis causes a severe and fatal disease called heartworm disease in dog. It also produces pulmonary nodules in humans. The worm is to be investigated as a potential infection of humans and animals in various provinces in Iran. In this research, the samples were studied with modified Knott’s test and molecular method. The results of the modified Knott’s test method indicated that 14.00% of sheepdogs were infected with filarial microfiler. The microfilers were characterized with basic morphological features, the length of the infective larva and tail ending. There was an estimated prevalence of 4.45% for Dirofilaria immitis and 9.55% for Acanthocheilonema reconditum microfiler. To verify the differential diagnosis, molecular method was performed using PCR with Dirofilaria specific primers for amplification of ITS2 locus. Gene locus sequencing results of D. immitis and sequence alignment recorded in GeneBank showed 97.00% similarity, and relatively 98.00% similarity was observed in A. reconditum. The results of the molecular method confirmed the result of modified Knott’s test method. Low infection with D. immitis was observed the region, probably due to the fact that the annual temperature and precipitation in this area were not suitable for the proliferation of the vector mosquitoes. In general, there was less infection in the region compared to regions with relatively similar climatic conditions. Hence, the results suggested that alternative diagnostic tests are required to determine the occult infections.

Survey on Zoonotic Importance and Prevalence of Dirofilaria immitis Infection in Dogs of Tabriz, Iran

Background: Dirofilaria immitis is one of the most important parasites of the circulatory system of dogs that causes severe cardiovascular events in the animal and it is reported to be the most common nematode in humans and dogs from many parts of Iran. Methods: In order to investigate the presence of Dirofilaria immitis infection in Tabriz, Iran, a cross-sectional study was performed on 200 owned and stray dogs. The blood samples were analyzed using Knott method. The prevalence of D. immitis infection was reported to be 15% in owned dogs. Results: The highest levels of infection were reported in dogs less than one year of age and the lowest in dogs aged over 9 years. In a statistical survey, there was a significant relationship between infection and gender. Conclusion: According to the findings of this study, due to the presence of D. immitis infection in this region, the need for a more comprehensive examination and control of the infection in this region is emphasized.

Filarial infections in dogs in Cyprus, an apparently heartworm free island.

The current study investigated for the first time the occurrence of filarial infections in dogs in Cyprus. Blood samples of dogs from five districts of Cyprus (Lefkosia, Lemessos, Larnaka, Pafos and Ammochostos) were examined by the modified Knott's method and by serology, and the morphological classification of microfilariae was confirmed by molecular methods. A total of 200 dogs, 153 living in shelters and 47 owned dogs, were included in the study. Acanthocheilonema reconditum microfilariae were found in 9 (4.5%) samples and one (0.5%) sample was seropositive for D. immitis. No statistical significance was observed between microfilaraemic samples and the evaluated variables apart from the district (p = .005). The present study showed that dogs in Cyprus can be infected with blood circulating microfilariae and for the first time A. reconditum was reported as autochthonous infection in dogs in the country. No microfilariae of Dirofilaria spp. were detected. However, veterinarians should remain vigilant regarding Dirofilaria infections and should consider preventive protection to the animals, at least in case of travel in enzootic areas.

Tuning of reinforcement learning parameters applied to SOP using the Scott–Knott method

In this paper, we present a technique to tune the reinforcement learning (RL) parameters applied to the sequential ordering problem (SOP) using the Scott–Knott method. The RL has been widely recognized as a powerful tool for combinatorial optimization problems, such as travelling salesman and multidimensional knapsack problems. It seems, however, that less attention has been paid to solve the SOP. Here, we have developed a RL structure to solve the SOP that can partially fill that gap. Two traditional RL algorithms, Q-learning and SARSA, have been employed. Three learning specifications have been adopted to analyze the performance of the RL: algorithm type, reinforcement learning function, and $$\epsilon $$ parameter. A complete factorial experiment and the Scott–Knott method are used to find the best combination of factor levels, when the source of variation is statistically different in analysis of variance. The performance of the proposed RL has been tested using benchmarks from the TSPLIB library. In general, the selected parameters indicate that SARSA overwhelms the performance of Q-learning.

Prevalence of dirofilariasis in shepherd and stray dogs in Iranshahr, southeast of Iran

Dirofilariasis is a zoonotic parasitic disease, which its cause Dirofilaria immitis, a nematode transmitted by insects and a worldwide dissemination. Dogs and cats are the main hosts of this parasite. Therefore, this study was conducted to determine the prevalence of D. immitis in shepherd and stray dogs in Iranshahr city, southeast of Iran. In this study 49 shepherd dogs and 50 stray dogs selected randomly and the blood samples were taken and sent to parasitology laboratory. Thin and thick thin blood samples were prepared and stained with Giemsa method and modified knott method. The obtained data were analyzed by SPSS 18 statistical software. The overall prevalence of parasite was 30.3%, seven of 49 shepherd dogs (14/3%) and twenty three of 50 stray dogs (46%) were positive. From 30 positive samples, 14.3% of shepherd dogs and 50% of stray dogs were male, and 44.7% of stray dogs were female. 14% of infected shepherd dogs and 38.5% of infected stray dogs were indigenous, and 16.7% of infected shepherd dogs and 72.7% of infected stray dogs were hybrids. There was no statistically significant relationship between the prevalence of D. immitis with age, gender, breed and usage of anti-parasitic drugs. Due to the relatively high contamination of dogs in the city of Iranshahr with this parasite, veterinarians and public health professionals should be considered necessary and preventive measures in relation to this disease.

Діагностика дирофіляріозу собак та епізоотична ситуація у Харківському регіоні України

Since September 2018 till February 2019 complex clinical laboratory research of 86 pure breed and 26 mongrel dogs (total112) at the ages from 1 to 14 of Kharkiv and its outskirts has been conducted in both private veterinary clinic “Doverie” (Kharkiv) and scientific laboratory of parasitology department of Kharkiv State Zooveterinary Academy. The purpose of research was to study the dirofilariosis spreading among dogs in Kharkiv and its outskirts. Investigation of dirofilariosis via blood test in dogs was done by Knott method (1939). The results of investigation were compared with Lateral flow immunoassay. Positive results of analysis had been smeared and dyed by Romanovsky-Gimze method. We have found out 24 dirofilariosis infested animals that made up 21.4% from examined amount. Microdirofilaria was found more frequently in blood of pure breed animals (54.2%) than mongrel ones (45.8%). But in case of general amount of taken animals in clinic, we can notice than out of 86 pure breed examined animals only 13 or 15.1% of dogs are infested by dirofilariosis, out of 26 mongrels – marked only 11 (42.3%). Among pure breed infested animals, the most susceptible was Central Asian Shepherd Dog (4 cases). Both German Shepherd and Russian Spaniel had two cases of diseases. The most dirofilariosis diseased ones were male dogs (66.7%), but females formed only third part (33.3%). Among 16 sick male dogs, only one was castrated, among 8 diseased female dogs – only one sterilized, that is 91.7% cases of fully sexual functional animals suffered from dirofilariosis. Dirofilariosis infested dogs were aged from 3 to 12. The most prevailed category of animals was aged from 4 to 9 (75%). It depends on dog weight; the most infested dogs were 12–20 kg (33.3%) and 21–30 kg (29.1%). Among dirofilariosis infested dogs, 41.7% were not undergone by insectoacaricide treatment, but 37.5% were regularly undergone by highly effective entomocide treatment. The most accurate from special laboratory methods was method of Lateral flow immunoassay (95.8%), 83.3% cases of diagnosed dirofilariosis were made by Knott method.

EVALUATION OF THE EFFICIENCY OF THREE TECHNIQUES FOR DIAGNOSIS OF THE CANINE DIROFILARIOSE

Introduction: Dirofilaria immitis is a filarid nematode that impacts dogs and other mammals worldwide, being transmitted by mosquito bites, causing heart failure without the dog that is the definitive host. The intermediate host may belong to several genera of mosquitoes such as Aedes, Anopholes and Culex. Objectives: this study aims to evaluate three techniques for the diagnosis of canine heartworm disease. Methods: it is an experimental analytical study. The tests were carried out on all wandering dogs adopted by a shelter in the city of Jaboatao dos Guararapes, Pernambuco, Brazil. Sample collection was performed in a dog with gag, antisected with iodinated alcohol for venous puncture in cephalic vein with a 5 ml disposable syringe and transferred to tube containing anticoagulant. He samples were processed at the Pet Life laboratory in Jaboatao dos Guararapes, Pernambuco, Brazil. Three techniques were employed, such as: Alere Dirofilariose Ag test kit; direct examination – thick smear drop and modified Knott’s method (1939). Of the total of 30 shelter dogs, 9 were males and 21 females. Results: Thirteen dogs presented positivity in the Alere Dirofilariose Ag Test Kit (43.33%), being 9 females and 4 males. Of the thirteen positive animals in the immunological method, ten were positive by the Knott Method (33.33%) and five were positive in the Thick Smear Drop test (16.66%). Conclusion: the presence of canine heartworm disease caused by D. immitis in a given region suggests that there may be human contamination causing pulmonary heartworm disease. This infection should be considered in the differential diagnosis of lung neoplasms and fungal infections. It was verified that the Alere Dirofilariose Ag Test Kit presented a high sensitivity in relation to the thick drop test and the Modified Knott Method, being able to evidence asymptomatic canine heartworm and nondetectable animals by the other techniques used.

Diagnosis of Early Stage of Dirofilariasis in Carnivores

The purpose of the research is to study methods of dirofilariosis diagnostics in comparative aspect and give analysis of therapy and prophylactics means. Materials and methods. Blood films of spontaneously infected dogs and experiment dogs and puppies were material for research. There were 5 puppies and 12 dogs of different age. After the death from dirofilariosis in experimental dogs, organs and tissues were examined, heart was opened and sexually mature dirofilarias were found. The sample for analysis was diluted with saline, the precipitate was examined under a microscope. A thick blood smear was stained using the Romanovsky-Giemsa method and was microscopically enlarged 140 times. To study blood and detect microfilaria in the blood, concentration methods were used: the Knott method using 1ml of fresh blood and 10 ml of a 2% formalin solution, the method using a 5% solution of acetic acid. Results and discussion. All studied methods are effective for detection microfilariae in the blood samples, however, the preferred method for us was the centrifugation method with distilled water, developed by V.B. and the method of thick crushed blood drop, since the detected microfilaria larvae remained viable and were used in experiments on the viability of microfilariae. Of the 45 samples examined, 10 detected microfilariae D. immitis. However, in most cases, the final diagnosis of dirofilariasis was made after the death of the host. In the zone endemic to the dirofilariasis, it is necessary to carry out continuous treatment of water reservoirs. Residential and non-residential premises treated with insecticides. Survey and de-worming of the invasive domestic dogs are carried out in the spring-summer period. Selamectin, moxidexin, ivermectin, dectomax, novomek, otodectin and others are applied. To prevent mosquitoes from contacting pets and humans long-acting repellents in the form of a spray, powder, emulsion, lotions are the most convenient to use.

Survey of Dirofilaria immitis in dogs from Sivas Province in the Central Anatolia Region of Turkey

In this research, we investigate the prevalence of Dirofilaria immitis infection in dogs using microscopical, serological, and molecular methods from the Central Anatolia Region (Sivas) of Turkey and reveal the associated risk factors. Whole blood and serum samples were obtained from 306 dogs older than 7 months. Polymerase chain reaction (PCR) and the modified Knott's method (Knott) were used for detecting the microfilaria and enzyme-linked immunosorbent assay (ELISA) was applied for the presence of D. immitis antigens. The prevalence of D. immitis in dogs was detected as 2.9% (9/306) by PCR and ELISA and as 1.3% (4/306) by Knott. All Knott-positive samples were also found positive by both PCR and ELISA. According to ELISA and PCR results, no statistically significant difference was found between the prevalence in males (4.2%) and females (1.5%); dogs 0.7?2 years old (2.5%), 3-5 years old (2.2%); and more than 6 years old (7.1%); or stray (3.7%) and owned (1.7%) dogs (P > 0.05). One of the PCR products was selected for sequence analyses of the 16S small subunit rRNA gene and the obtained sequence was submitted to GenBank (KJ183078). The 16S rRNA sequence exhibited 100% identity to other D. immitis sequences available in GenBank (FJ799911, FJ799917, FJ799916). This research provides the first data on D. immitis infections in dogs from Sivas Province by using the combined identification techniques.

The prevalence of canine dirofilariosis in the region of Attiki

Blood samples of 900 dogs living in the area of Attiki (Greece) were examined. The dogs were over one year old, of different breeds, both sexes and didn't receive heartworm chemoprophylaxis or chemotherapy. All samples were examined by the modified Knott's method for the detection of microfilariae, while a serological examination (ELISA kit PetChek®, IDEXX) for the detection of parasitic antigen was performed to 552 of them. Six out of 900 (0.7%) of the samples were found positive for Dirofìlaria immitis: in 2 of them both microfilariae and parasitic antigen were detected, in 3 only parasitic antigen and in 1 sample only microfilariae were detected. The animals, in which microfilariae D. immitis were detected, were hunting dogs, often taken for hunting out of Attiki region. Moreover, in 4 of the 900 samples (0,4%) microfilariae Dirofìlaria repens were found. According to these results, the prevalence of D. immitis infection of the dog in Attiki is low. Preventive measures such as chemoprophylaxis against dirofilariosis must be taken in order to keep the infection at low level in Attiki.

Prevalence of bovine microfilariasis in Rayalaseema region of Andhra Pradesh.

The Prevalence of microfilariasis of bovines was studied in four districts of Rayalaseema region of Andhra Pradesh with respect to species, age, breed, sex and physiological status viz., lactation, season for a period of 1year. A total of 1286 blood samples were examined by conventional techniques viz. Wet blood film, blood smear examination and Knott's method with an overall prevalence of 2.72% (35/1286) was recorded in bovines. The prevalence observed in buffaloes and cattle was 2.97% (20/672) and 2.45% (15/614) respectively. With respect to region, higher rate of infection was recorded in Kurnool (3.25%) followed by 3.12, 2.5 and 2.01% in Anantpaur, Chittoor and Kadapa districts, respectively. The infection was higher in female animals (2.79%) whereas no positive case could be detected among the 32 male animals screened. Breed wise analysis revealed, highest prevalence was observed in cross bred cattle (3.04%) and graded Murrah (3.67) than non-descriptive cattle (0.64%) and buffalo (1.89%). Significantly higher prevalence was noticed in the age group of above 9years (4.72%) followed by 6-9years (2.98%), 3-6years (2.05%) and below 3years (1.04%). In lactating animals significantly higher prevalence was observed (3.47%) followed by non-lactating animals (2.65%) and heifers (0.47). Further higher prevalence was detailed during rainy season (3.89%) in comparison to summer (2.87%) and winter (1.25%) season.

Dirofilaria infections in dogs in different areas of Greece.

BackgroundThe nematodes Dirofilaria immitis and D. repens are enzootic in Greece. In the light of evidence of dirofilariosis spreading to new areas around the world, the aim of the present study was to update and enrich the current knowledge on the prevalence of Dirofilaria infections in dogs in Greece, to assess the risk factors of heartworm infection, and to initiate the drawing of the epizootiological map of canine dirofilariosis, investigating Dirofilaria infections in five locations along the north-south axis of the country, i.e. municipalities of Thessaloniki, Larissa, Achaia, Attica and Heraklion, associated with the five largest urban centres of Greece.MethodsBlood samples collected from 750 dogs in total, were examined by the modified Knott’s method and by serology. A questionnaire including information about each examined dog was filled in and statistical analysis of the results was performed using the Chi-square test and a Binary Multiple Univariate Generalized Linear Model.ResultsIn total, 31 (4.1 %) out of 750 examined animals were found positive for D. immitis by any of the tests applied (Knott’s method and serological examination). Moreover, microfilariae of D. repens and Acanthocheilonema reconditum were detected by the Knott’s method in 17 (2.3 %) and 10 (1.3 %) of the animals, respectively. At the municipality level, the prevalence of infection was 14, 7, 5.3, 0.7 and 0 % for D. immitis, 1, 2, 8.7, 0.3 and 0 % for D. repens, and 0, 3, 2.7, 0.7 and 1 % for A. reconditum in Thessaloniki, Larissa, Achaia, Attica and Heraklion, respectively. In addition, in three dogs (one each in Thessaloniki, Achaia and Attica) mixed D. immitis - D. repens infections were detected by the Knott’s method. The area of the country, dog’s usage and age were determined as risk factors for heartworm infection.ConclusionsNorthern areas of Greece have higher Dirofilaria prevalence and the prevalence in a western province (Achaia) is recorded for the first time. The mosquito population dynamics recorded in the past is likely to play an important role in the distribution of Dirofilaria infections in Greece, and needs further investigation. Similarly, the role of wild reservoirs of filarial parasites in different areas needs to be clarified. Promotion by veterinarians of preventive treatment and compliance by pet owners is essential in all parts of Greece, regardless of the recorded prevalence of infection.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1797-6) contains supplementary material, which is available to authorized users.

Genetic divergence of physiological-quality traits of seeds in a population of peppers.

Brazil has a great diversity of Capsicum peppers that can be used in breeding programs. The objective of this study was to evaluate genetic variation in traits related to the physiological quality of seeds of Capsicum annuum L. in a segregating F2 population and its parents. A total of 250 seeds produced by selfing in the F1 generation resulting from crosses between UFPB 77.3 and UFPB 76 were used, with 100 seeds of both parents used as additional controls, totaling 252 genotypes. The seeds were germinated in gerboxes containing substrate blotting paper moistened with distilled water. Germination and the following vigor tests were evaluated: first count, germination velocity index, and root and shoot lengths. Data were subjected to analysis of variance, and means were compared by Scott and Knott's method at 1% probability. Tocher's clustering based on Mahalanobis distance and canonical variable analysis with graphic dispersion of genotypes were performed, and genetic parameters were estimated. All variables were found to be significant by the F test (P ≤ 0.01) and showed high heritability and a CVg/CVe ratio higher than 1.0, indicating genetic differences among genotypes. Parents (genotypes 1 and 2) formed distinct groups in all clustering methods. Genotypes 3, 104, 153, and 232 were found to be the most divergent according to Tocher's clustering method, and this was mainly due to early germination, which was observed on day 14, and would therefore be selected. Understanding the phenotypic variability among these 252 genotypes will serve as a basis for continuing the breeding program within this family.