The use of spatial analysis to estimate the prevalence of canine leishmaniasis in Greece and Cyprus to predict its future variation and relate it to human disease

Antileishmanial activity of Ptilostemon chamaepeuce subsp. cyprius

BACKGROUND

Phytochemicals from unexplored plant species may be vital to unlocking pharmaceutical antibiotic and antiparasitic discoveries. New compounds need to be discovered to combat antimicrobial resistance. This study aimed to investigate ethanolic leaf extracts from five endemic and four indigenous plants from Cyprus for antibacterial, antileishmanial, and antioxidant activities.

METHODS

Ethanolic leaf extracts were screened for antibacterial activity using a broth microdilution assay and iodonitrotetrazolium chloride (INT) as a colourimetric redox indicator for determining the minimum inhibitory concentration (MIC) against four Gram-positive and two Gram-negative American Type Culture Collection (ATCC) reference bacteria. Total phenolic content (TPC), total flavonoid content (TFC) and radical scavenging activity assays were performed to screen for antioxidant potential. Leishmania infantum clinical culture (MCAN/CY/2005/CD57) was used to screen the extracts for in vitro antileishmanial activity. Their cytotoxicity in vitro was assessed using the resazurin fluorometric assay with a HepG2 cell line. As an estimate of in vitro toxicity, a brine shrimp lethality assay was performed.

RESULTS

The ethanol extract of Ptilostemon chamaepeuce subsp. cyprius (Greuter) Chrtek & B. Slavik demonstrated antibacterial activity against Enterococcus faecalis (ATCC 29212) with minimum inhibitory concentration (MIC) < 0.625 mg/mL and antileishmanial activity against a clinical isolate of L.infantum (MCAN/CY/2005/CD57) from an infected dog (promastigote IC50 of 105.7 ± 2.5 μg/mL and amastigote IC50 of 118.5 ± 4.3 μg/mL) after 48 h and compared to the activity of the reference drug, miltefosine (IC50 of 3.7 ± 0.1 μg/mL and 18.5 ± 2.3 μg/mL, respectively). Liquid-chromatography-mass spectrometry (LC-MS) analysis revealed the presence of at least five sesquiterpene lactones (STLs) in P. cham. subsp. cyprius ethanolic extract. The main compound, deacylcynaropicrin, based on its high-resolution mass spectrum, is believed to be primarily responsible for the antileishmanial activity observed in vitro. Quercus alnifolia Poech ethanolic extract showed antibacterial activity against four Gram-positive and one Gram-negative bacteria with MIC values of < 0.625 mg/mL, respectively, and antioxidant capacity in DPPH radical scavenging assay with IC50 of 0.155 ± 0.002 mg/mL and compared to ascorbic acid (IC50 of 0.036 ± 0.000 mg/mL) and Trolox (IC50 of 0.047 ± 0.001 mg/mL).

CONCLUSION

The ethanolic extract of Ptilostemon chamaepeuce subsp. cyprius demonstrated dose-dependent antileishmanial activity. This is the first data report of P.cham. subsp. cyprius and Q.alnifolia ethanolic extracts to indicate antibacterial, antileishmanial and antioxidant activities in preliminary investigations. Moreover, this is the first report on STLs in P. cham. subsp. cyprius, and future studies are needed to confirm if they are responsible for the in vitro antileishmanial activity. These findings highlight the potential of these endemic plants as sources for developing new drugs targeting Gram-positive bacterial infections and leishmaniasis, encouraging further pharmaceutical research.

Plasmodium cynomolgi: potential emergence of new zoonotic malaria in Southeast Asia

The reported cases of Plasmodium cynomolgi in Southeast Asia pose a significant public health concern. Sporadic reports of human Plasmodium cynomolgi infections have increased in the past few years, raising attention regarding its potential impact on human populations. Further compounding this issue are the morphological similarities between P. cynomolgi and the human malaria parasite Plasmodium vivax, which may lead to misdiagnosis and underreporting of P. cynomolgi infections. Both in vitro and in vivo studies have shown that P. cynomolgi can effectively invade human reticulocytes using mechanisms like those employed by P. vivax, underscoring its capacity to infect human hosts if given the opportunity. These studies collectively highlight the parasite's potential to establish infections in humans and emphasize the need for molecular diagnostic tools to accurately detect P. cynomolgi. Additionally, challenges in accurate diagnosis and surveillance systems may underestimate the true extent of their impact, making it imperative for healthcare authorities to bolster monitoring efforts and deploy targeted interventions. Strengthening surveillance, improving diagnostic capabilities, and developing targeted vector control strategies are crucial to mitigating the risk of P. cynomolgi becoming a major zoonotic disease like its counterpart, Plasmodium knowlesi. Thus, this review aims to highlight the current understanding of P. cynomolgi infections in human, vector, and macaque hosts based on collated data from previous studies while underscoring the urgent need for enhanced surveillance, accurate diagnostic tools, and effective vector control strategies to mitigate its potential as a significant zoonotic threat in Southeast Asia.

Leishmaniosis in Greece: The Veterinary Perspective

Leishmaniosis caused by the protozoon Leishmania infantum that is transmitted through the bites of infected phlebotomine sandflies is of major veterinary concern in Greece. The country is endemic with particularly favourable environmental conditions for the spread of this infection. Moreover, Greece remains a popular touristic destination, and the continuous travel of pets raises concern regarding the possible dissemination of infection from endemic to non-endemic areas. Dogs are the main reservoir host, although other animal species, including humans, may also be infected. Canine leishmaniosis manifests as a visceral disease that can result in death if left untreated. Serological and molecular epizootiological studies have confirmed circulation of the parasite in Greek canine and feline populations as well as in other mammals. As a result, constant surveillance and identification of high-risk localities are necessary to establish chemoprophylactic protocols for travelling animals to safeguard animal and public health.

Serological Survey of Canine Vector-Borne Infections in North-Center Spain

Various factors are currently causing an increase in vector-borne parasitic diseases at a global scale; among them, some stand out, such as climatic disturbances derived from global change, the increase in movements of reservoir animals, or changes in land made by human activity. In the European continent, there have been an increasing number of epidemiological studies focused on the detection of these diseases, especially in dogs. In Spain, there are few epidemiological studies focused on the evaluation of the biotic and abiotic factors that may influence the distribution, such as climatic zones, orography, or presence of water reservoirs. The aim of this study was to analyze the prevalence and distribution of several canine vector-borne diseases caused by Dirofilaria immitis, Leishmania infantum, Anaplasma platys, and Ehrlichia canis in the autonomous community of Castilla y León, the largest region of the Iberian Peninsula, providing a geospatial approach based on a geographic information system (GIS) analysis. Blood from a total of 1,475 domestic dogs from the nine provinces of Castilla y León were analyzed. Also, a GIS analysis of the sample locations was carried out, taking into account the most important predictor variables. The prevalence in dogs infected by D. immitis was 7.19%, and the seroprevalence by L. infantum was 4.61 and 1.56% for A. platys and E. canis. Most of the infected animals were located in areas with stagnant water, irrigated agriculture, or riverbanks, always close to forest and woodland vegetation. These results indicate that dogs living in Castilla y León should take prophylactic measures to avoid infections.

Canine Leishmaniosis in Greece: An Updated Countrywide Serological Study and Associated Risk Factors

Canine leishmaniosis (Leishmania infantum) is a zoonotic disease that affects dogs worldwide. Greece is enzootic for this disease, and updated data for its current distribution are of major importance. The aim of this cross-sectional serological study was primarily to update the current knowledge of Leishmania infantum seropositivity status within the asymptomatic Greek canine population and, furthermore, to assess the possible climatological and other risk factors. In total, sera of 1265 asymptomatic dogs were collected from all prefectures of the country. A questionnaire that included all individual dog information was completed for all animals. The Speed Leish K^® canine Leishmania antibody test kit (BVT Groupe Virbac, France) was employed. Potential risk factors were evaluated utilizing logistic regression models. Overall, 13.8% (n = 175) of the sampled dogs were seropositive to Leishmania infantum originating from all geographical departments of the country, whereas most prefectures had at least one seropositive animal. Outdoor living, high mean humidity, low mean wind speed and high total annual rainfall were found to increase the seropositivity status against the parasite. Conclusively, Leishmania infantum remains a common parasite challenge in the asymptomatic canine population of Greece, and therefore, its early diagnosis and effective prevention are significant in the country.

Angiostrongylus vasorum in Domestic Dogs in Castilla y León, Iberian Peninsula, Spain

Simple Summary

Canine angiostrongylosis is a vascular and pulmonary disease caused by Angiostrongylus vasorum. In Europe, there has been an increasing number of studies showing a rise in the studies in both domestic and wild canids. In Spain, angiostrongylosis is still little-known, and studies are scarce. The aim of this study was to analyze the presence of A. vasorum in 1475 domestic dogs from the autonomous region of Castilla y León (Spain). Antigens of this species were found in 0.75% of the tested dogs, most of which lived outdoors, a significant risk factor. The geographic information system (GIS) analysis showed that the infected animals mainly lived in areas with mild temperatures and climate during most of the year and close to water bodies: stagnant water; riverbanks or irrigated areas with a predominance of alder, holm oak and gall oak forests. One main conclusion was the need to carry out more studies in countries and areas with the presence of this parasite in order to know the prevalence in dogs and wild canids, as well as determine the environmental factors that influence its presence, to be able to take more effective measures to control this disease.

Abstract

Angiostrongylus vasorum is the causative agent of canine angiostrongylosis, a disease affecting domestic and wild canids. In Europe, it is an emerging disease, mainly reported in red foxes. In Spain, there are a few studies that address the prevalence and pathology of this disease. Castilla y León is the largest region of the Iberian Peninsula, whose extensive area is 94,224 km²; however, until now, there have been no epidemiological studies on this disease. Therefore, the aim of this study was to analyze the presence of antigens of A. vasorum in 1475 dogs from Castilla y León, showing an overall prevalence of 0.75%. The infected dogs were mainly outdoors, guard and hunting breed dogs and living in locations with mild climates close to areas of high edaphic humidity, such as stagnant water, irrigated crops or riverbanks, with the vegetation dominated by alders, holm oak and gall oak forests, where the intermediate hosts develop. It is necessary to carry out more in-depth studies on the epidemiology and pathology of this disease in Spain and Europe in order to carry out efficient control in both domestic and wild animals.

Mapping the canine vector-borne disease risk in a Mediterranean area

Background

The aim of this study was to determine exposure to vector-borne pathogens (VBPs) in populations of dogs living on Greek islands in the Ionian and Aegean seas.

Methods

In total, 1154 dogs with different lifestyles and of varying ages and breeds were randomly sampled and examined for the presence of clinical signs compatible with canine vector-borne diseases (CVBDs). Blood was collected from each individual animal. For the detection of antibodies against Leishmania spp., the WITNESS® Leishmania test was performed, and positive samples were further examined with indirect enzymatic immunoassay (ELISA). Antibodies to Borrelia burgdorferi, Ehrlichia canis or E. ewingii, as well as Anaplasma phagocytophilum or A. platys were investigated using the Snap® 4Dx® Plus test. Positive Ehrlichia spp. and Anaplasma spp. samples were further examined using an indirect ELISA for further identification of the species.

Results

In total, 25.6% of dogs were exposed to at least one of the pathogens investigated, with seroprevalences varying regionally. Of these seropositive dogs, 27.4% displayed clinical signs suggestive of CVBDs, such as cutaneous lesions, enlarged lymph nodes, pale mucous membranes, onychogryphosis and weight loss. The overall seroprevalence detected using the rapid tests was 15.3% for Leishmania spp., whereas 2.3% of the examined dogs were found to be positive for Anaplasma spp. and 7.5% for Ehrlichia spp. while B. burgdorferi was not detected. Twenty-four samples positive to A. phagocytophilum by ELISA were analysed by PCR for the presence of Anaplasma DNA. PCR and sequencing results showed the presence of A. platys DNA in 4 samples and E. canis DNA in 4 samples. The remaining samples (66.7%) were negative.

Conclusions

In the present study, exposure of dogs to VBPs was shown in the geographical areas investigated. Results confirm that on Greek islands VBPs represent a constant health risk for both native and visiting dogs, suggesting the presence of distinct “hot-spots” of VBP infections on different islands. In order to reduce the risk of transmission and the spread to non-endemic regions, the protection of dogs through use of repellents and vaccines, together with owner education, seem to be of paramount importance.

Childhood Visceral Leishmaniasis: Distinctive Features and Diagnosis of a Re-emerging Disease. An 11-year Experience From a Tertiary Referral Center in Athens, Greece

BACKGROUND

Visceral leishmaniasis (VL) remains a public health issue in Greece. The aim of this study was to describe the clinical and epidemiologic characteristics of pediatric VL in our region as well as to evaluate the laboratory findings and the diagnostic techniques that are applied.

METHODS

We retrospectively reviewed the medical records of all children diagnosed with VL in an 11-year period at a tertiary public hospital in the region of Athens. Demographic features, clinical information and laboratory findings were accessed.

RESULTS

A total of 43 cases were recorded during 2005-2015. Median age of the patients was 3.7 years. Pallor (100%), fever (98%), hepatosplenomegaly (55.8%) and appetite loss (32.6%) were the most common presentations of the disease. The predominant laboratory abnormalities were anemia (100%), thrombocytopenia (90.7%), elevated inflammatory markers (86.1%) and decreased albumin/globulin (A/G) ratio (72.1%). Four patients developed secondary hemophagocytic lymphohistiocytosis syndrome, whereas in 3 others abdominal ultrasound showed splenic nodules. Bone marrow aspiration detected Leishmania parasites in 92.7% of cases and the rapid rK39 strip test indicated anti-Leishmania antibodies in 97.1% of children. In addition, all patients in whom indirect immunofluorescent antibody test was implemented had positive results.

CONCLUSIONS

VL still affects children in our area. Fever, splenomegaly, anemia and appetite loss are the typical findings in children. Noninvasive techniques (immunofluorescent antibody test, rK39) in combination with bone marrow microscopy are useful in the diagnosis of pediatric VL.

Leishmania incidence and prevalence in U.S. hunting hounds maintained via vertical transmission

Leishmania is the causative agent of leishmaniasis, a deadly protozoan disease which affects over 1 million people each year. Autochthonous cases of canine leishmaniasis are generally associated with tropical and subtropical climatic zones. However, in 1999, U.S. hunting dogs were found to have leishmaniasis with no history of travel outside the country. Transmission of this disease was found to be primarily vertical. In endemic areas, dogs are a dominant domestic reservoir host for Leishmania infantum. This study evaluated L. infantum infection prevalence and incidence within US dogs tested over a nine-year span (2007-2015). This investigation used both passive and active surveillance, following an initial outbreak investigation by the Centers for Disease Control. L. infantum infection incidence and prevalence over time and across regions were examined to evaluate whether transmission was sufficient to maintain ongoing infection within this population. These studies also established whether this disease is becoming more or less prominent within this reservoir host, dogs. There was no significant difference between prevalence and incidence rates via as measured by passive vs. active surveillance. Although due to fluctuations in sample submission there were significant changes in both incidence and prevalence of L. infantum in US hunting dogs over this nine year span, these differences were not outside of the interquartile range and therefore there is likely to be a steady-state of transmission within U.S. dogs. Based on these findings, if vertical transmission is the primary means of L. infantum spread in U.S. dogs, with appropriate husbandry and infection control procedures, elimination of L. infantum from US dogs could be possible.

Environmental parameters as risk factors for human and canine Leishmania infection in Thessaly, Central Greece

Thessaly, Central Greece, is an endemic area for leishmaniasis with higher incidence rate during the last years. We herein investigated the geographical distribution of human leishmaniasis cases and Leishmania infected dogs in relation to environmental parameters to identify high-risk areas. All the human leishmaniasis cases (n = 82) reported to Hellenic Centre for Disease Control and Prevention from 2007 to 2014 and 85 Leishmania polymerase chain reaction positive dogs were included in this study. To analyse the data geographical information system (GIS) together with the Ecological Niche Model (ENM) were used. The most important findings of the study were: (i) Central plain of Thessaly together with the coast line and the western and eastern lowlands were identified as high-risk geographical areas. (ii) The highest percentage of the high-risk areas was found in low altitude (<200 m above sea level) and in irrigated and cultivated agricultural areas. (iii) A total of 20% of the human settlements was found in high-risk areas. (iv) The maximum temperature of the warmest month contributes the highest per cent to define both environmental niche profiles for humans and dogs. (v) The ENM could be a useful tool for the epidemiological study of leishmaniasis. Spatial analysis may allow the design of entomological studies and identify target population in order to implement preventive measures.