Seroprevalence and asymptomatic carriage of Leishmania spp. in Austria, a non-endemic European country

The changing epidemiology of human leishmaniasis in the non-endemic country of Austria between 2000 to 2021, including a congenital case

BACKGROUND

Leishmaniasis is caused by infection with intracellular protozoans of the genus Leishmania. Transmission occurs predominantly by the bite of phlebotomine sandflies, other routes, including congenital transmission, are rare. The disease manifests as either cutaneous, visceral or mucosal/mucocutaneous leishmaniasis. In recent years, changes in the epidemiological pattern have been reported from Europe.

PRINCIPAL FINDINGS

A total of 311 new and 29 published leishmaniasis cases occurring between 01/01/2000 and 12/31/2021 in Austria were collected and analyzed. These encompassed 146 cutaneous (CL), 14 visceral (VL), 4 mucosal, and 3 cases with concurrent VL and CL. In addition, asymptomatic infections, comprising 11 unspecified cases with Leishmania DNA detectable only in the blood and 162 cases with anti-Leishmania antibodies were reported. Particularly since 2016, the incidence of leishmaniasis has steadily risen, mainly attributable to increasing numbers of CL and cases with positive serology against Leishmania species, whereas the incidence of VL has slowly decreased. Analysis revealed that a shift in the causative species spectrum had occurred and that a substantial number of CL cases were caused by members of the Leishmania donovani/infantum complex. Simultaneous occurrence of VL and CL was identified in immunocompromised individuals, but also in a not yet reported case of an immunocompetent child after vertical transmission.

CONCLUSIONS

The incidence of leishmaniasis has risen in the recent years. The numbers are anticipated to keep rising due to increasing human mobility, including travel and forced migration, growing reservoir host populations as well as expansion and dispersal of vector species caused by climate and habitat changes, urbanization and globalization. Hence, elevated awareness for the disease, including possible transmission in previously non-endemic regions and non-vector transmission modes, support of sandfly surveillance efforts and implementation and establishment of public health interventions in a One Health approach are pivotal in the global efforts to control and reduce leishmaniasis.

Non-Endemic Leishmaniases Reported Globally in Humans between 2000 and 2021—A Comprehensive Review

Leishmaniases are human and animal parasitic diseases transmitted by phlebotomine sand flies. Globalization is an important driver of the burden and in the current dynamics of these diseases. A systematic review of articles published between 2000 and 2021 was conducted using the PubMed search engine to identify the epidemiology and clinical management of imported human leishmaniases as a fundamental step to better manage individual cases and traveler and migrant health from a global perspective. A total of 275 articles were selected, representing 10,341 human imported cases. Identified drivers of changing patterns in epidemiology include conflict and war, as well as host factors, such as immunosuppression, natural and iatrogenic. Leishmania species diversity associated with different clinical presentations implies diagnostic and treatment strategies often complex to select and apply, especially in non-endemic settings. Thus, diagnostic and management algorithms for medical clinical decision support are proposed. Increased surveillance of non-endemic cases, whether in vulnerable populations such as refugees/migrants and immunocompromised individuals or travelers, could improve individual health and mitigate the public health risk of introducing Leishmania species into new areas.

Feline Leishmaniosis: An Emerging Public Health Problem

Leishmaniosis is the third most important vector-borne disease in humans, preceded by malaria and lymphatic filariasis, and it is considered endemic in tropical and subtropical areas, where higher temperatures favor development of its vector, sandflies. This zoonotic disease is caused by infection of protozoa Leishmania spp. and the most serious mucocutaneous and visceral form is produced by Leishmania infantum, which predominates in the Mediterranean region. The usual hosts for this parasite are dogs and humans, but an increment in cases of L. infantum infection has been observed in cats in the last years. This increase could be due to the use of sandflies repellents in dogs, obligating the parasite to looking for other hosts. The role of cats in the epidemiology of this disease is unknown, although increase of prevalence of feline leishmaniosis has been observed in endemic areas in the last years. Diagnostic techniques and treatments in cats are not standardized, which makes it difficult to establish prevalence and epidemiology of feline leishmaniosis. Furthermore, the clinical signs and immune response against Leishmania in cats are different to those in dogs, with an observed increment of drug resistance. It is necessary to increase our knowledge about L. infantum infection in cats, including clinical signs, transmission, treatments, and the role of cats in the increasing of zoonoses. Finally, new alternative treatments are required for controlling the spread of this disease in all species of mammals.

Asymptomatic Visceral Leishmania infantum Infection in US Soldiers Deployed to Iraq

BACKGROUND

Visceral leishmaniasis (VL), due to Leishmania infantum, is a persistent intracellular parasitic infection transmitted by the bite of infected sand flies. Symptomatic VL has been reported in U.S. soldiers with Iraq deployment. Untreated symptomatic VL can be fatal; asymptomatic VL (AVL) may establish a lifelong risk of reactivation. We report prevalence and AVL risk factors in Operation Iraqi Freedom (OIF) deployers during 2002-11.

METHODS

Healthy soldiers exposed to VL endemic areas in Iraq and 50 controls who never traveled to endemic regions were recruited through military healthcare facilities (2015-17). Responses to a risk factor survey and blood samples were obtained. Leishmania research diagnostics utilized included enzyme-linked immunosorbent assay (ELISA), rk39 test strips, quantitative polymerase chain reaction (PCR), and interferon gamma release (IGRA) assays. Statistical analyses included Fisher exact test, Pearson χ2 test, Mann-Whitney U test, and logistic regression.

RESULTS

200 deployed subjects were enrolled, mostly males (84.0%), of white ethnicity (79.0%), and median age 41 (range 24-61) years. 64% were seropositive for Phlebotomus alexandri saliva antibodies. Prevalence of AVL (any positive test result) was 39/200 (19.5%, 95% confidence interval 14.4%-25.8%). Two (1.0%) PCR, 10 (5%) ELISA, and 28 (14%) IGRA samples were positive. Travel to Ninewa governorate increased risk for AVL (P = .01).

CONCLUSION

AVL was identified in 19.5% of OIF deployers; travel to northwest Iraq correlated with infection. Further studies are needed to inform risk for reactivation VL in US veterans and to target additional blood safety and surveillance measures.

Molecular detection and characterization of Leishmania infantum in free-ranging Egyptian mongoose (Herpestes ichneumon)

Wild mammals are susceptible to infection by Leishmania parasites. Although canine leishmaniasis is widely distributed in mainland Portugal, the sylvatic cycle of the parasite remains poorly understood. In this study, the occurrence of L. infantum in wild carnivores from Portugal was assessed by molecular screening of 132 hunted or accidentally road-killed animals. Spleen samples from Egyptian mongoose, red fox, stone marten, common genet and European badger were tested by amplification of Leishmania kinetoplastid DNA and ITS1. Five egyptian mongoose were confirmed Leishmania DNA-positive by kDNA-PCR. Phylogenetic analysis of a kDNA amplicon sequence clustered the strain with L. infantum sequences from Portugal. These results may suggest that L. infantum strains circulating in wild animals are genetically related with strains from more humanized settings. Exposure of wild carnivores to Leishmania infantum emphasizes the need of systematic studies to clarify the role of several taxa in the eco-epidemiology of leishmaniasis in Portugal, particularly in areas of carnivore species synanthropy and wherein disease control in the domestic population is inefficient or insufficient.

Leishmania spp. seropositivity in Austrian soldiers returning from the Kosovo

Leishmaniasis is a severe vector-borne disease with two main clinical forms, visceral leishmaniasis and cutaneous leishmaniasis. Both forms of leishmaniasis are also endemic in Mediterranean countries including the Balkan region from where mainly visceral leishmaniasis is reported. Austrian soldiers returning from Kosovo were screened for anti-Leishmania antibodies to assess the risk of infection during operations. Anti-Leishmania antibodies were detected in more than 20% of the soldiers investigated, which indicates a considerable risk of infection during missions in this area and thus suggests the application of protective measures.

Phlebovirus seroprevalence in Austrian Army personnel returning from missions abroad

Background

Phleboviruses are mainly transmitted by sand flies and infections can result in various symptoms, including meningitis and meningoencephalitis. In endemic regions, seroprevalences in humans and animals are high. Military personnel on missions in endemic areas are at increased risk of infection, however, for soldiers from central European countries, data are scarce. The aims of this study were to determine the exposure to phleboviruses of Austrian soldiers returning from missions abroad and to assess potential risk factors. A retrospective serological study was performed with sera of 753 healthy Austrian soldiers returning from missions in Bosnia and Herzegovina (BIH, n = 61), Kosovo (n = 261), Syria (n = 101) and Lebanon (n = 63) and of soldiers prior to their missions (n = 267).

Results

Altogether, 119 sera (15.8%, 119/753) were positive for anti-Phlebovirus IgG antibodies, with highest seroprevalences found in soldiers returning from Kosovo (20.69%, 54/261), followed by Syria (17.82%, 18/101), Lebanon (14.29%, 9/63) and BIH (11.48%, 7/61). Of the soldiers tested prior to their missions 11.61% (31/267) were positive. Of the 119 seropositive individuals, 30 (25.2%, 30/119) also had anti-Phlebovirus IgM antibodies. Phlebovirus seropositivity significantly correlated with symptoms of febrile illness during the respective mission (OR: 1.9, 95% CI: 1.1–3.4, P = 0.03) and with Leishmania seropositivity (OR: 2.7, 95% CI: 1.2–5.8, P = 0.009). Also, the outdoor activity “running” during the mission showed a strong trend towards an association with Phlebovirus seropositivity (OR: 1.9, 95% CI: 0.9–4.4, P = 0.08), and seropositivity generally increased with the duration of a mission (OR: 2.5, 95% CI: 0.9–7.5, P = 0.07).

Conclusions

This study indicates that soldiers are exposed to sand flies and at significant risk for Phlebovirus infection during missions in the Mediterranean area and the Middle East. Adequate prevention measures should be applied particularly during vespertine outdoor activities.

Subclinical Leishmania infection in patients with rheumatic diseases under biological drugs

PURPOSE

Climate changes and immunosuppression are influencing the spread of leishmaniasis and re-emergence in Northern Italy, respectively. We evaluated the prevalence of subclinical leishmaniasis in patients from a Northern Italian region with chronic inflammatory rheumatism (CIRD) receiving biological drugs (BD) and correlated it to the area of residence.

METHODS

DNA from PBMC of patients affected by CIRD treated with either BD for at least 5 years (Group A) or other immunosuppressive drugs (Group B) was investigated by a qPCR for Leishmania infantum kDNA and compared to healthy subjects (Group C). Variables such as sex and age, rural areas, dog ownership, type of BD administered and association between BD and steroids, were evaluated by statistical analysis.

RESULTS

A higher proportion of L. infantum DNA positivity was found in Group A than in Group C (p < 0.05), while no parasite DNA was detected in Group B. In Group A, 18/50 patients (36%) had higher rates of parasite DNA (from 1 to 136 to 1.000.000 copies/ml) than Group C (from 1 to 10 copies/ml). 14/18 (77.7%) of positive patients from Group A lived in rural areas, but no statistical differences occurred in relation to dog ownership or BD type (p < 0.0003).

CONCLUSIONS

We can speculate that exposure to rural areas appears to be a factor closely linked with the risk of developing Leishmania subclinical infection. A screening with molecular methods in patients with CIRD treated with BD living in these areas and monitoring Leishmania DNA during such therapies, would be mandatory to prevent delay in diagnosis should VL symptoms appear.

Leishmania infections in Austrian soldiers returning from military missions abroad: a cross-sectional study

OBJECTIVES

The incidence of leishmaniasis is known to increase in conflict areas. The aims of this study were to determine the exposure to Leishmania species in Austrian soldiers returning from missions abroad and to assess possible risk factors.

METHODS

A retrospective explorative cross-sectional serologic study was conducted in 225 healthy Austrian soldiers returning from UN or EU peacekeeping missions in Syria, Lebanon and Bosnia and Herzegovina (BIH). Sera were tested for anti-Leishmania antibodies using a commercial enzyme-linked immunosorbent assay. All positive individuals were screened for Leishmania DNA by PCR targeting the ITS1 region using EDTA blood samples.

RESULTS

In total, 13.3% (30/225) of the individuals tested were either positive (8%, 18/225) or borderline (5.3%, 12/225) in the enzyme-linked immunosorbent assay, with the highest seroprevalence in soldiers returning from Syria (17.8%, 18/101; 12 positive, six borderline), second from Lebanon (11.1%, 7/63; four positive, three borderline) and lowest from BIH (8.2%, 5/61; two positive, three borderline). Ten soldiers returning from Syria and one from BIH were also positive for Leishmania DNA. Six of these were identified as Leishmania donovani/infantum complex, two as L. tropica and another three as mixed infections by DNA sequencing. Epidemiologic data were collected via a questionnaire, and seropositivity was correlated with a history of insect bites that took a long time to heal (odds ratio, 5.33; 95% confidence interval, 1.23-23.04; p 0.025).

CONCLUSIONS

Although pretravel serologic data were not available in this study, the exposure of soldiers to Leishmania spp. during their missions can be assumed to be considerable. Because even asymptomatic infections may resurge in case of emerging immunodeficiencies, adequate prevention measures seem important.

Could Phlebotomus mascittii play a role as a natural vector for Leishmania infantum? New data

Background

The occurrence of phlebotomine sand flies in Central Europe was questioned until they were recorded for the first time in Germany in 1999, and ten years later also in Austria. The aim of this study was to investigate sand flies collected in Austria for their carrier status of Leishmania spp.

Findings

From 2012 to 2013 field studies were conducted in eastern Austria. Altogether, 22 individuals of sand flies were found, all morphologically identified as Phlebotomus (Transphlebotomus) mascittii Grassi, 1908. Twelve non-engorged female specimens with no visible remnants of a blood meal in their bodies were individually investigated for Leishmania spp. by ITS-1 real-time PCR. One out of these was positive for Leishmania, identified as Leishmania infantum by DNA sequencing. This finding suggests that L. infantum is not excreted by P. mascittii and possibly can establish an infection within P. mascittii. Interestingly, an asymptomatic dog living on the farm where this sand fly had been caught was also Leishmania-positive.

Conclusions

This study provides new data on the suspected vector capacity of P. mascittii, being the northernmost sand fly species in Europe and in most central European regions the only sand fly species found. Proven vector capacity of P. mascittii for Leishmania spp. would be of significant medico-veterinary importance, not only with respect to expanding sand fly populations in Central Europe related to global warming, but also in the light of globalization and increasing movements of humans.

Seroepidemiology and molecular diversity of Leishmania donovani complex in Georgia

BACKGROUND

Leishmaniasis includes multiple clinical syndromes, most notably visceral, cutaneous, and mucosal forms. Visceral leishmaniasis (VL), also known as kala-azar, is a potentially fatal disease endemic to large parts of Africa and Asia, and in South-Eastern Europe (Greece, Turkey, Georgia). Visceral leishmaniasis is a parasitic zoonosis caused by species of the L. donovani complex. In the classical epidemiological model the main reservoir for VL are canines.

METHODS

The study included a cohort of 513 individuals of both genders (190 males and 323 females) from the ages of 1 to 70 years that were screened in ten villages across two districts in Kakheti using the Kalazar Detect™ rK39 rapid diagnostic test. The phylogenetic diversity patterns of local strains, based on the rDNA internal transcribed spacer (ITS) sequences, were assessed for samples obtained from patients with suspected L. donovani infection, from canine reservoirs and from Phlebotomus sand flies obtained from different geographical areas of Georgia and from Azerbaijan.

RESULTS

Out of a total of 600 domestic dog blood samples 95 (15.8 %) were positive by rK39 rapid diagnostic tests. For symptomatic domestic dogs, the testing of conjunctival swabs or bone marrow aspirates revealed a higher VL incidence in Kvareli District (Kvareli; 19.4 %, n = 329) compared with that observed for Sagarejo District (Sagarejo; 11.4 %, n = 271). A total of 231 sand flies of both genders were collected during the 2-month period; of the 114 females, 1.75 % were PCR positive for the presence of Leishmania spp.

CONCLUSIONS

VL infection rates remain high in both canines and humans in Georgia, with disease in several known natural foci. The genetic relationships derived from rDNA internal transcribed spacer (ITS) sequence comparisons identified genetic subgroups, revealing preliminary insights into the genetic structure of L. donovani complex members currently circulating in the South Caucasus and demonstrates the utility of ITS-based genotyping in the resource-limited country of Georgia.

Leishmaniosis of companion animals in Europe: an update

Leishmaniosis caused by Leishmania infantum is a vector-borne zoonotic disease endemic in southern Europe, but which is spreading northwards. Millions of dogs, cats and other non-conventional companion animals susceptible to L. infantum, living in European households, may develop a severe disease and contribute to the spread of leishmaniosis because of travelling or re-homing. Dogs are the main reservoir but other new reservoirs have recently been incriminated. Sand flies remain the sole proven vector and non-vectorial transmission has been reported at individual level and in areas where the vector is absent. Clinical disease affects only a proportion of infected dogs and a complex genetic background of immune response is responsible for this susceptibility. There is a wide range of serological and parasitological diagnostic tools available whose cost-effective use depends on a reasoned approach. Clinical response to treatment of sick dogs is variable. Clinical cure is often obtained but clinical recurrence can occur and post-therapy follow up should be maintained life-long. In Europe, vaccination can be combined with individual protection with pyrethroids as part of an integrated approach to prevention. L. infantum is the only species isolated from cats in Europe and xenodiagnosis substantiated that infected cats are infectious for sand flies. Feline infection may be frequent in endemic areas, but prevalence is generally lower than in dogs. When cats are tested by both serological and molecular techniques discordant results are often observed. Feline cases have been reported from endemic areas in Italy, France, Spain and Portugal, but four cases were also diagnosed in Switzerland in cats that had travelled to or been imported from Spain. Half of the cases were diagnosed in cats with impaired immune responses. Clinical manifestations compatible with feline leishmaniosis include lymph node enlargement, skin and mucocutaneous lesions, ocular lesions, chronic gingivostomatitis, hypergammaglobulinemia, and normocytic normochromic anemia. Cats have been empirically treated with some drugs used in dogs. Due to polymorphic clinical picture and the insidious progressive course, leishmaniosis can persist for a long time before dogs or cats are brought to a veterinarian and so diagnosis can be delayed. Exotic or new Leishmania spp. have been reported in humans, animals and vectors in Europe. This changing situation requires attention in Europe for designing epidemiological studies and control measures.

Factors influencing the presence of sand flies in Majorca (Balearic Islands, Spain) with special reference to Phlebotomus pernicious, vector of Leishmania infantum

BACKGROUND

Although the Mediterranean island of Majorca is an endemic area of leishmaniosis, there is a lack of up-to-date data on its sand fly fauna, the last report dating from 1989. The aim of the present study was to provide information on the current sand fly distribution, the potential environmental factors favoring the presence of Phlebotomus perniciosus and which areas are at risk of leishmaniosis.

METHODS

In July 2008 sand fly captures were carried out in Majorca with sticky castor oil interception traps. The capture stations were distributed in 77 grids (5x5 km2) covering the entire island. A total of 1,882 sticky traps were set among 111 stations. The characteristics of the stations were recorded and maps were designed using ArcGIS 9.2 software. The statistical analysis was carried out using a bivariate and multivariate logistic regression model.

RESULTS

The sand fly fauna of Majorca is composed of 4 species: Phlebotomus perniciosus, P sergenti, P. papatasi and Sergentomyia minuta. P. perniciosus, responsible for Leishmania infantum transmission, was captured throughout the island (frequency 69.4 %), from 6 to 772 m above sea level. Through logistic regression we estimated the probability of P. perniciosus presence at each sampling site as a function of environmental and meteorological factors. Although in the initial univariate analyses the probability of P. perniciosus presence appeared to be associated with a wide variety of factors, in the multivariate logistic regression model only altitude, settlement, aspect, drainage hole construction, adjacent flora and the proximity of a sheep farm were retained as positive predictors of the distribution of this species.

CONCLUSIONS

P. perniciosus was present throughout the island, and thereby the risk of leishmaniosis transmission. The probability of finding P. perniciosus was higher at altitudes ranging from 51 to 150 m.a.s.l., with adjacent garrigue shrub vegetation, at the edge of or between settlements, and in proximity to a sheep farm.

Emergence of sandflies (Phlebotominae) in Austria, a Central European country

The possible existence of autochthonous sandfly populations in Central Europe north of the Alps has long been excluded. However, in the past years, sandflies have been documented in Germany, Belgium, and recently, also in Austria, close to the Slovenian border. Moreover, autochthonous human Leishmania and Phlebovirus infections have been reported in Central Europe, particularly in Germany. From 2010 to 2012, sandfly trapping (740 trap nights) was performed at 53 different capture sites in Austria using battery-operated CDC miniature light traps. Sites were chosen on the basis of their climate profile in the federal states Styria, Burgenland, and Lower Austria. Sandfly specimens found were transferred to 70 % ethanol for conservation. Identification was based on morphological characters of the male genitalia and the female spermathecae, respectively. Altogether, 24 specimens, 22 females and 2 males, all identified as Phlebotomus (Transphlebotomus) mascittii Grassi, 1908, were found at six different sampling sites in all three federal states investigated. The highest number of catches was made on a farm in Lower Austria. Altogether, the period of sandfly activity in Austria was shown to be much longer than presumed, the earliest capture was made on July 3rd and the latest on August 28th. Sandflies have been autochthonous in Austria in small foci probably for long, but in the course of global warming, further spreading may be expected. Although P. mascittii is only an assumed vector of Leishmania spp.—data on its experimental transmission capacity are still lacking—the wide distribution of sandflies in Austria, a country thought to be free of sandflies, further supports a potential emergence of sandflies in Central Europe. This is of medical relevance, not only with respect to the transmission of Leishmania spp. for which a reservoir is given in dogs, but also with respect to the phleboviruses.

Clinical Challenges in the Management of Leishmania/HIV Coinfection in a Nonendemic Area: A Case Report

We report on a 37-year-old male HIV-positive patient with generalized cutaneous leishmaniasis undiagnosed for several years. Upon presentation, visceral leishmaniasis was diagnosed in addition to cutaneous manifestation of the disease. Over a period of three years, several different treatment regimens including liposomal amphotericin B, liposomal amphotericin B with miltefosine, liposomal amphotericin B with interferon, and pentamidine combined fluconazole and allopurinol were applied until Leishmania PCR from blood turned negative. This case supports the necessity of multidrug combinational and sequential therapy over a very prolonged period of time in severely immunosuppressed patients infected with Leishmania and highlights the tremendous individual but also economic burden of this disease.