Serological evidence of Leishmania donovani infection in apparently healthy dogs using direct agglutination test (DAT) and rk39 dipstick tests in Kafta Humera, north-west Ethiopia

Leishmania donovani Transmission Cycle Associated with Human Infection, Phlebotomus alexandri Sand Flies, and Hare Blood Meals, Israel1

Cutaneous leishmaniasis caused by Leishmania major or L. tropica and visceral leishmaniasis caused by L. infantum have been reported in Israel. We collected Phlebotomus spp. sand flies in the Negev desert of southern Israel to identify circulating Leishmania spp. Of 22,636 trapped sand flies, 80% were P. alexandri. We sequenced Leishmania-specific internal transcribed spacer 1 fragments and K26 genes. Of 5,019 Phlebotomus female sand flies, 2.5% were Leishmania DNA-positive; 92% of infections were L. donovani. Phylogenetic analyses showed separate clustering of L. donovani and L. infantum. P. alexandri flies positive for L. donovani harbored blood meals from European hares. Leishmania DNA isolated from a patient with cutaneous leishmaniasis who lived in the survey area was identical to L. donovani from P. alexandri flies. We report circulation of L. donovani, a cause of visceral leishmaniasis, in southern Israel. Prompt diagnosis and Leishmania spp. identification are critical to prevent leishmaniasis progression.

Livestock and rodents within an endemic focus of Visceral Leishmaniasis are not reservoir hosts for Leishmania donovani

Leishmaniasis on the Indian subcontinent is thought to have an anthroponotic transmission cycle. There is no direct evidence that a mammalian host other than humans can be infected with Leishmania donovani and transmit infection to the sand fly vector. The aim of the present study was to evaluate the impact of sand fly feeding on other domestic species and provide clinical evidence regarding possible non-human reservoirs through experimental sand fly feeding on cows, water buffalo goats and rodents. We performed xenodiagnosis using colonized Phlebotomus argentipes sand flies to feed on animals residing in villages with active Leishmania transmission based on current human cases. Xenodiagnoses on mammals within the endemic area were performed and blood-fed flies were analyzed for the presence of Leishmania via qPCR 48hrs after feeding. Blood samples were also collected from these mammals for qPCR and serology. Although we found evidence of Leishmania infection within some domestic mammals, they were not infectious to vector sand flies. Monitoring infection in sand flies and non-human blood meal sources in endemic villages leads to scientific proof of exposure and parasitemia in resident mammals. Lack of infectiousness of these domestic mammals to vector sand flies indicates that they likely play no role, or a very limited role in Leishmania donovani transmission to people in Bihar. Therefore, a surveillance system in the peri-/post-elimination phase of visceral leishmaniasis (VL) must monitor absence of transmission. Continued surveillance of domestic mammals in outbreak villages is necessary to ensure that a non-human reservoir is not established, including domestic mammals not present in this study, specifically dogs.

An experimental challenge model for Leishmania donovani in beagle dogs, showing a similar pattern of parasite burden in the peripheral blood and liver

Leishmania donovani and Leishmania infantum are closely related species. However, the former is considered the causative agent for anthroponotic visceral leishmaniasis (AVL), while the latter is known to be responsible for zoonotic visceral leishmaniasis (ZVL) with dogs as the main reservoir host. Although molecular detection of L. donovani from naturally infected dogs has been reported in AVL endemic areas, the experimental infection of dogs with this species is very limited. Here, we constructed an experimental canine visceral leishmaniasis (CVL) model with L. donovani infection using beagle dogs. During an observation period of 8 months after parasite inoculation, few clinical symptoms were observed in the three inoculated dogs. The overall hematological and biochemical data of the dogs showed normal levels, and there were no remarkable changes in the peripheral CD4⁺, CD8⁺, CD25⁺, or FoxP3⁺ T cell populations. Liver biopsy sampling was conducted to monitor the parasite burden in the liver. A similar pattern of the amount of mitochondrial kinetoplast DNA was observed in the peripheral blood and liver by real-time PCR analysis. In addition, parasite antigens were detected from the liver biopsy sections by immunohistochemical analysis, further supporting the existence of parasites in the liver. These results showed a subclinical CVL model for L. donovani in beagle dogs with a similar kinetics of parasite burden in the peripheral blood and liver.

Dried Blood Spots technology for veterinary applications and biological investigations: technical aspects, retrospective analysis, ongoing status and future perspectives

Dried Blood Spots (DBS) technology has become a valuable tool in medical studies, however, in veterinary and biological research DBS technology applications are still limited. Up-to-date no review has comprehensively integrated all the evidence existing across the fields, technologies and animal species. In this paper we summarize the current applications of DBS technology in the mentioned areas, and provide a scope of different types of dried sample carriers (cellulose and non-cellulose), sampling devices, applicable methods for analyte extraction and detection. Mammals, birds, insects and other species are represented as the study objects. Besides the blood, the review considers a variety of specimens, such as milk, saliva, tissue samples and others. The main applications of dried samples highlighted in the review include epidemiological surveys and monitoring for infections agents or specific antibodies for disease/vaccination control in households and wildlife. Besides the genetic investigations, the paper describes detection of environmental contaminants, pregnancy diagnosis and many other useful applications of animal dried samples. The paper also analyses dried sample stability and storage conditions for antibodies, viruses and other substances. Finally, recent developments and future research for DBS technology in veterinary medicine and biological sciences are discussed.

Domestic mammals as reservoirs for Leishmania donovani on the Indian subcontinent: Possibility and consequences on elimination

Leishmania donovani is the causative agent of historically anthroponotic visceral leishmaniasis (VL) on the Indian subcontinent (ISC). L. donovani is transmitted by the sand fly species Phlebotomus argentipes. Our collaborative group and others have shown that sand flies trapped outside in endemic villages have fed on cattle and dogs in addition to people. Domestic animals are reservoirs for L. donovani complex spp., particularly L. infantum, in other endemic areas. Multiple studies using quantitative PCR or serological detection methods have demonstrated that goats, cattle, rats and dogs were diagnostically positive for L. donovani infection or exposure in eastern Africa, Bangladesh, Nepal and India. There is a limited understanding of the extent to which L. donovani infection of domestic animals drives transmission to other animals or humans on the ISC. Evidence from other vector-borne disease elimination strategies indicated that emerging infections in domestic species hindered eradication. The predominant lesson learned from these other situations is that non-human reservoirs must be identified, controlled and/or prevented. Massive efforts are underway for VL elimination on the Indian subcontinent. Despite these herculean efforts, residual VL incidence persists. The spectre of an animal reservoir complicating elimination efforts haunts the final push towards full VL control. Better understanding of L. donovani transmission on the Indian subcontinent and rigorous consideration of how non-human reservoirs alter VL ecology are critical to sustain elimination goals.

Prevalence and risk factors of Toxoplasma gondii and Leishmania spp. infections in apparently healthy dogs in west Shewa zone, Oromia, Ethiopia

BACKGROUND

In urban settings, the presence of a high density of the human population and contact with domestic and/or stray animals such as dogs and cats can be risk factors for the transmission of zoonotic protozoa parasites. Toxoplasma gondii (T. gondii) and Leishmania spp. are zoonotic protozoon parasites with significant health burdens worldwide.

METHODS

A cross-sectional study was used to investigate the antibody prevalence and risk factors of T. gondii and Leishmania spp. infections in 385 randomly selected dogs of Ambo, Bako, and Gojo towns of West Shewa Zone, Oromia regional state, Ethiopia. A questionnaire survey was administered to households to collect data on potential risk factors. Dog sera samples were assayed for T. gondii IgG antibodies using the direct agglutination test while Leishmania spp. specific antibodies tested using an indirect enzyme-linked immunosorbent assay (ELISA). Logistic regression was used for data analysis.

RESULTS

Overall, T. gondii and Leishmania spp. infection seroprevalence was found to be 82.86% (95% confidence interval (CI): 78.71-86.49%) and 92.47% (95% CI: 89.36-94.90%), respectively. Seropositivity for both T. gondii and Leishmania spp. was found in 82.58% of the dogs. None of the investigated factors were associated with Leishmania spp. seropositivity (p > 0.05). The seroprevalence of T. gondii was significantly different among the study towns (p = 0.003). The risk of T. gondii infection was 2.71 times higher in adult dogs than juvenile dogs (p = 0.043). Dogs kept simultaneously with other domestic animals had increased odds of T. gondii seropositivity compared to those with no other domestic animals (Adjusted Odds ratio: 1.96, p = 0.021). However, altitude, sex, breed, housing, feeding, educational level of head of the household, and dog's living area were not significantly associated with T. gondii seropositivity (p > 0.05).

CONCLUSIONS

The high seropositivity and the simultaneous presence of antibodies of T. gondii and Leishmania spp. in dogs suggest the widespread nature of these parasites in the environment and the high potential of transmission to other animals and humans. Further epidemiological studies, isolation and molecular characterization of the parasites, and educational campaigns are suggested.

Prioritization of neglected tropical zoonotic diseases: A one health perspective from Tigray region, Northern Ethiopia

Neglected tropical zoonotic diseases (NTZDs) continue to have a major effect on the health of humans and animals. In this study, a one health approach was used to prioritize and rank neglected tropical zoonotic diseases at the regional and zonal levels in Tigray National Regional State, Ethiopia. For prioritization of NTZDs a cross-sectional study through a structured questionnaire was administered to 313 health experts from human and animal health sectors. In addition, focus group discussions (FGD) were held with purposively selected key informants. Descriptive, and Multivariable analysis was applied to report the results and a ranked list of diseases was developed at the zonal and regional level. In the region, 8 of the 12 World Health Organization listed NTZDs were considered major diseases including anthrax, brucellosis, bovine tuberculosis, taeniasis, leishmaniasis, rabies, schistosomiasis, and soil-transmitted helminths. Considering the zoonotic and socioeconomic importance of the diseases at the regional level, rabies ranked 1^stwhereas anthrax, bovine tuberculosis, leishmaniasis, and brucellosis were ranked from 2^nd to 5^th, respectively. The FGD result also supported the prioritization result. The Multivariable analysis showed a statistically significant difference in the zonal distribution of anthrax (р = 0.009, OR = 1.16), taeniasis (p<0.001, OR = 0.82), leishmaniasis (p<0.001, OR = 1.91), rabies (p = 0.020, OR = 0.79) and soil-transmitted helminths (p = 0.007, OR = 0.87) but not for brucellosis (p = 0.585), bovine tuberculosis (p = 0.505), and schistosomiasis (p = 0.421). Anthrax (p<0.001, OR = 26.68), brucellosis (p<0.001, OR = 13.18), and taeniasis (p<0.001, OR = 6.17) were considered as the major zoonotic diseases by veterinary practitioners than human health practitioners whereas, leishmaniasis was recognized as a major health challenge by human health professionals. Understanding the priority diseases in the region is supportive for informed decision-making and prioritizes the limited resources to use. Furthermore, strengthening the collaboration between human and animal health professions is important to control the diseases.

Neglected tropical zoonotic diseases in Tigray region, northern Ethiopia: Spatial distribution and trend analysis of rabies, tuberculosis, schistosomiasis, and visceral leishmaniasis in humans

Neglected tropical zoonotic diseases (NTZDs) continue to affect the health and livelihoods of humans particularly the poor and marginalized populations in developing countries. Mapping the distribution and burden of these diseases will support making an informed decision. A retrospective study was conducted to map the spatial distribution and analyse trend of NTZDs in Tigray region, Northern Ethiopia. A health management information system (HMIS) data between 2012/13 and 2016/17 was obtained from Tigray National Regional State Health Bureau. The Quantum-GIS software was used to map the spatial distribution and burden of selected NTZDs at zonal level. Only four of the NTZDs namely rabies, tuberculosis (TB), schistosomiasis and visceral leishmaniasis (VL) from the records of HMIS data were considered. A high incidence rate (IR) at least for one of the NTZDs was reported in males above 15 years old. In the 5-year period, of the 60,099 reported NTZD cases, 30.3% (18,220), 26.6% (16,005), 23.3% (14,001), 14.4% (8,661), and 5.3% (3,212) were, respectively, schistosomiasis, extra-pulmonary TB, rabies, pulmonary TB, and visceral leishmaniasis. The year-wise analysis showed an irregular trend for the NTZDs where both the decreasing and increasing trends didn't show statistically significant variation. However, the overall regional number of TB cases showed a decreasing trend, where the decrease for extra-pulmonary TB (1.8 cases per 100,000 population) was higher than pulmonary TB (0.5 cases per 100,000 population). Similarly, the annual number of rabies and VL cases showed a decreasing trend. On the other hand, the number of schistosomiasis cases showed an increasing trend (8.2 cases per 100,000 population). The annual average number of TB (171 cases per 100,000 population), schistosomiasis (354 cases per 100,000 population), and VL (63 cases per 100,000 population) cases were much higher in Western zone compared to the rest of the zones. The incidence rate of rabies was higher in Mekelle and Southeastern (100 cases per 100,000 population) and Northwestern (97 cases per 100,000 population) zones. Intervention strategies applied in the region should take into account the zonal distribution and burden of NTZDs.

Validation of the Use of Dried Blood Samples for the Detection of Toxoplasma gondii Antibodies in Stray Cats (Felis s. catus)

If validated beforehand, the analysis of dried blood on blotting paper (BP samples) is very useful for monitoring free-ranging animals. We aimed to validate this method for the detection of antibodies against Toxoplasma gondii in stray cats. We used the modified agglutination test (MAT) in 199 sample pairs of sera and BP samples from 54, 39, 56, and 50 cats trapped during four periods in five dairy farms. Screening was at 1:6, 1:12, and 1:24 dilutions. The cut-off value was at MAT titre ≥ 24, but MAT titre ≥ 12 was also considered for BP samples that often have a higher dilution level. Depending on the period, sample type, and cut-off value, sensitivity of the analysis of the BP sample vs. serum varied from 87.1% to 100% and specificity ranged from 72.22% to 100%. The concordance values and Kappa coefficient showed a substantial to excellent agreement between the results of the two methods, whatever the cut-off value. These findings quantifiably validate the use of MAT on BP samples for the detection of antibodies to T. gondii in stray cats, but we recommend expressing results from BP samples with several cut-off values as the MAT titres tend to be lower than those of sera.

Molecular and serological evaluation of zoonotic visceral leishmaniasis in dogs in a rural area of Fars province, southern Iran, as a source of Leishmania infantum infection

Canine visceral leishmaniasis (CVL) is endemic in the southern parts of Iran. The current study aimed at molecular and serological evaluation of zoonotic visceral leishmaniasis in dogs in Fars province, southern Iran. Blood samples were collected from 60 dogs in the three villages in Fars Province. Serum samples were tested for antibodies against L. infantum by direct agglutination test (DAT). DNA was extracted from each dog's buffy coat and tested by PCR, targeting the Leishmania ITS‐2 region. From a total of 60 studied dogs, 25 (41.7%) were female, and 35 (58.3%) were male. Dogs' age ranged from 1 to 7 years, with a mean age of 2.97 (±1.4) years. Anti‐Leishmania antibodies were detected in sera samples of 28 (46.7%) dogs, (titre ≥ 1:320). Out of 28 seropositive cases, 13 (46.4%) were female, and 15 (53.6%) were male. Association between seropositivity and dogs’ clinical signs was statistically significant (p < .05). Leishmania DNA was detected in the buffy coat of 3 of 60 studied dogs which were all seropositive by DAT. The PCR products were sequenced and molecular analysis showed that two of the isolates were Leishmania infantum, and one was L. tropica. The high proportion of seropositive dogs indicates the important role of these animals in the epidemiology of the disease in the region. Infected dogs with or without signs, especially those that are molecularly positive, can act as an active reservoir of the disease in the area.

Prevalence of asymptomatic visceral leishmaniasis in human and dog, Benishangul Gumuz regional state, Western Ethiopia

BACKGROUND

The Benishangul-Gumuz region is an important development corridor in Ethiopia. Large-scale projects such as the Great Renaissance Dam, mining and agriculture have entailed huge environmental modifications and settlement pattern changes. There is no detailed epidemiological information on visceral leishmaniasis (VL) in the region.

MATERIALS AND METHODS

A cross-sectional study was carried out to assess the epidemiology and risk factors associated with Leishmania infection. A leishmanin skin test (LST) was done for 1342 participants, and for 253 of them rK39 and DAT were carried out. Thirty-six dogs owned by households with LST-positive member(s) were rK39 and DAT tested. A pretested questionnaire was used to capture individual and household characteristics.

RESULTS

Of the 89.2% (1197/1342) who availed themselves of the LST reading, 6.0% were positive. The rk39 and DAT positivity among the 253 tested were 3.2% and 5.9%, respectively. In dogs, positivity rates by rK39 and DAT were 13.9% and 5.6%, respectively. Of the household and individual risk factors, presence of a dog in the household (P = 0.005), male sex (0.003), residence woreda (0.000) and occupation (0.023) showed a strong positive association with LST positivity. Individuals who lived in households that had dogs were 2.6 times more likely to be LST positive (AOR = 2.6; 95% CI = 1.54, 4.40). Being female decreased the probability of being LST positive by 0.38 times (AOR = 0.38; 95% CI = 0.20, 0.72). People living in Guba and Kurmuk had 4.7 (AOR = 4.74, 95% CI 1.83, 12.31) and 5.9 (AOR = 5.85, 95% CI 2.27, 15.09) times more risk of being infected.

CONCLUSIONS

We demonstrated the presence of active VL transmission in the areas. Thus, we underline the need to establish the responsible vector(s) and reservoir(s) for comprehensive early containment plans to prevent potentially harmful public health and economic consequences.

Studies of host preferences of wild-caught Phlebotomus orientalis and Ph. papatasi vectors of leishmaniasis in Sudan

Introduction

Understanding the feeding behavior and host choice of sand flies provides valuable information on vector-host relationships and elucidates the epidemiological patterns of leishmaniasis transmission. Blood meal analysis studies are essential for estimating the efficiency of pathogen transmission, assessing the relative human disease risk, and assist in identifying the other potential hosts of leishmaniasis. In Sudan and most of East Africa, there are large remaining gaps in knowledge regarding the feeding habits of phlebotomine vectors. The study aimed to identify the blood meal sources and, therefore, the host preferences of the principal vectors Phlebotomus orientalis and Ph. papatasi in leishmaniasis endemic areas of eastern and central Sudan.

Materials and methods

Sand flies were collected from two endemic villages in eastern and central Sudan using CDC light traps and sticky traps. The phlebotomine sand flies were morphologically and then molecularly identified. The source of blood meal of the engorged females was determined using a multiplex PCR methodology and specific primers of cytochrome b gene of mitochondrial DNA for human, goat, cow, and dog. The detection of the Leishmania parasite was done using PCR.

Results

The total number of collected female phlebotomine sand flies was 180. Morphological identification revealed the abundance of Ph. orientalis 103 (57.2%), Ph. papatasi 42 (23.3%), Ph. bergeroti 31 (17.2%), Ph. rodhaini 2 (1.1%) and Ph. duboscqi 2 (1.1%) in the study sites. Out of the 180 collected, 31 (17%) were blood-fed flies. Three species were blood-fed and molecularly identified: Ph. papatasi (N = 7, 22.6%), Ph. bergeroti (N = 9, 26%), and Ph. orientalis (N = 15, 48.4%). Blood meal analysis revealed human DNA in two Ph. orientalis (6.4%), hence, the anthropophilic index was 13.3%.

Conclusions

Multiplex PCR protocol described here allowed the identification of blood meal sources of many vertebrate species simultaneously. The results indicate that wild-caught Ph. orientalis are anthropophilic in the study areas. Further studies on larger blood-fed sample size are required to validate the potential applications of this technique in designing, monitoring and evaluating control programs, particularly in investigating the potential non-human hosts of leishmaniasis.

A molecular analysis of sand fly blood meals in a visceral leishmaniasis endemic region of northwestern Ethiopia reveals a complex host-vector system

Background

Visceral leishmaniasis (VL, or “kala-azar”) is a major cause of disability and death, especially in East Africa. Its vectors, sand flies (Diptera: Psychodidae: Phlebotominae), are poorly controlled and guarded against in these regions, owing in part to a lack of understanding about their feeding behavior.

Methods

A total of 746 freshly fed female sand flies were collected in five population centers in Kafta Humera (northwestern Ethiopia), where VL is endemic. Flies were collected from habitats that ranged from inside houses to open fields, using light traps and sticky traps. Sources of sand fly blood meals were identified using enzyme-linked immunosorbent assays (ELISA) and DNA amplification with reverse-line blot analysis (PCR-RLB); 632 specimens were screened using ELISA, 408 of which had identifiable blood meals, and 114 were screened using PCR-RLB, 53 of which yielded identifications. Fly species determinations were based on morphology, and those specimens subjected to PCR-RLB were also screened for Leishmania parasites using conventional PCR to amplify the nuclear marker ITS1 (internal transcribed spacer 1) with Leishmania-specific primers.

Results

More than three-fourths of all sand flies collected were Phlebotomus orientalis, and the remaining portion was comprised of nine other species. Nearly two-thirds of P. orientalis specimens were collected at village peripheries. The most common blood source for all flies was donkey (33.9% of all identifications), followed by cow (24.2%), human (17.6%), dog (11.8%), and goat or sheep (8.6%); mixtures of blood meals from different sources were found in 28.2% of all flies screened. Unidentified blood meals, presumably from wildlife, not domestic animals, were significantly higher in farm fields. Leishmania parasites were not detected in any of the 114 flies screened, not surprising given an expected infection rate of 1–5 out of 1,000. Meals that included a mixture of human and cow blood were significantly more frequent relative to all cow meals than human blood meals were to non-cow meals, suggesting a zoopotentiative interaction between cows and humans in this system.

Conclusions

Habitat and host preferences of sand fly vectors in Kafta Humera confirmed the finding of previous reports that the main vector in the region, Phlebotomus orientalis, is a highly opportunistic feeder that prefers large animals and is most commonly found at village peripheries. These results were similar to those of a previous study conducted in a nearby region (Tahtay Adiabo), except for the role of cattle on the prevalence of human blood meals. Preliminary examinations of blood meal data from different settings point to the need for additional surveys and field experiments to understand the role of livestock on biting risks.

Leishmaniasis in Ethiopia: A systematic review and meta-analysis of prevalence in animals and humans

Leishmaniasis is a neglected tropical disease caused by obligate intracellular protozoa of the genus Leishmania. Ethiopia does not have an overall estimation of prevalence of leishmaniasis infection at a country level. The objective of this systematic review and meta-analysis was to summarize and pool estimates of studies that report the prevalence of leishmaniasis in Ethiopia. The literature search was conducted to identify all published studies reporting the prevalence of leishmaniasis with clearly designed inclusion and exclusion criteria. From all screened articles, 30 studies were eligible for final meta-analysis and systematic review. Because substantial heterogeneity was expected, random-effects meta-analyses were carried out using the total sample size and number of positives to estimate the prevalence of the disease at a country level. Between-study variability was high (τ² = 0.02; heterogeneity I² = 99.72% with Heterogeneity chi-square = 11985.41, a degree of freedom = 33 and P = 0.001). The overall random pooled prevalence of leishmaniasis was 19% (95% CI 14%-24%). Meta-regression analysis showed that diagnosis method used have contributed to the heterogeneity of studies. Molecular diagnosis has significantly lower prevalence than microscopic examination with a coefficient of -0.32, a p-value of 0.024, and CI (-0.6-0.05). The result of effect estimates against its standard error showed there was no publication bias with a P value of 0.084. This review indicated that there is still a higher prevalence of Leishmaniasis in the country. Reporting on risk factors like sex and age affected, species of Leishmania involved and many more other risk factors reviewing was not possible in this study due to lack of completeness in articles included. However, this report is an indication that the country needs nationally coordinated extensive prevention and control plan to reduce public health and socio-economic impact of the disease.

Serological investigation of visceral Leishmania infection in human and its associated risk factors in Welkait District, Western Tigray, Ethiopia

Visceral leishmaniasis (VL) is major neglected public health problem in terms of geographical spread and incidence in Ethiopia. Magnitude, public health impact and dynamics of VL were not well studied in Welkait District, Western Tigray, though the area is known for VL. Hence, this study aimed to determine sero-prevalence of human VL and associated risk factors in Welkait as new foci. A cross sectional study design was employed in this study. Two stage stratified random sampling method was used to select study participants. Hence, a total of 329 human study participants were included for serological survey using ITleish and leishmanin skin tests. Semi structured questionnaire was also used to identify VL associated risk factors. Univariate and multivariate logistic regression statistical methods were used to determine the degree of association. The overall sero-prevalence of human VL in the study area was found to be 8.81%. Statistical significant difference in the prevalence of the disease was found among Sub-districts, sex, re-settlement, sleeping outdoor and dog ownership (P < 0.05). Participants who resettled from their original place were found 2 times (AOR = 2.143; 95% CI = 1.02, 14.20) more vulnerable to VL infection. Those who had an experience of sleeping outdoor were found almost 4 times (AOR = 4.29; 95% CI = 1.58, 11.69) more likely to be at risk of acquiring VL infection than those sleep indoor. Furthermore, individuals who owned dogs were 3 times more prone to the VL infection than their counterparts (AOR = 3.37; 95% CI = 1.29, 8.76). Alarming sero-positivity of human VL was recorded from new foci. Hence, it is recommended to improve the VL health services in the study area. The investigation also invites further study on VL dynamics in the study area.

Molecular and Serological Evidence of Leishmania Infection in Stray Dogs from Visceral Leishmaniasis-Endemic Areas of Bangladesh

Visceral leishmaniasis (VL), or kala-azar, is mainly caused by two closely related Leishmania species, Leishmania infantum and Leishmania donovani Leishmania infantum is responsible for zoonotic VL, with dogs as the main reservoir host in the Mediterranean, the Middle East, Asia, and South America. In the Indian subcontinent, VL is caused by L. donovani and is considered anthroponotic, although the only known vector, the sand fly, is zoophilic in nature. The role of domestic and stray dogs in VL transmission is still unclear in this area. We screened 50 stray dogs from VL-endemic areas of Bangladesh for serological and molecular evidence of Leishmania infection. We detected anti-Leishmania antibodies in six (12%) dog serum samples using rK39 immunochromatographic tests. We observed Leishmania kinetoplast DNA in 10 (20%) buffy coat DNA samples by real-time polymerase chain reaction (PCR), five of which were positive based on internal transcribed spacer 1-PCR. A sequencing analysis of the amplified products confirmed that the parasitic DNA was derived from L. donovani Our findings support the hypothesis that stray dogs are an animal reservoir for L. donovani in this endemic region. Further studies are required to determine the precise role of dogs in the epidemiology of VL in Bangladesh.

Exposure to Leishmania spp. and sand flies in domestic animals in northwestern Ethiopia

Background

Human visceral leishmaniasis caused by Leishmania donovani is considered an anthroponosis; however, Leishmania-infected animals have been increasingly reported in L. donovani foci, and the role of these animals as reservoirs for human L. donovani infection remains unclear.

Methods

We conducted a study of domestic animals (goats, sheep, cows, dogs, and donkeys) in three L. donovani foci in northwestern Ethiopia. Domestic animals were screened for Leishmania DNA and for anti-L. donovani IgG. Serum anti-sand fly saliva antibodies were used as a marker of exposure to the vector sand fly, Phlebotomus orientalis.

Results

Of 546 animals tested, 32 (5.9 %) were positive for Leishmania DNA, with positive animals identified among all species studied. Sequencing indicated that the animals were infected with parasites of the L. donovani complex but could not distinguish between L. infantum and L. donovani. A total of 18.9 % of the animals were seropositive for anti-L. donovani IgG, and 23.1 % of the animals were seropositive for anti-P. orientalis saliva IgG, with the highest seroprevalence observed in dogs and sheep. A positive correlation was found between anti-P. orientalis saliva and anti-L. donovani IgGs in cows, goats, and sheep.

Conclusions

The detection of L. donovani complex DNA in the blood of domestic animals, the reported seroprevalence to the L. donovani antigen, and the widespread exposure to sand fly saliva among domestic animals indicate that they are frequently exposed to Leishmania infection and are likely to participate in the epidemiology of Leishmania infection, either as potential blood sources for sand flies or possibly as parasite hosts.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-0976-1) contains supplementary material, which is available to authorized users.

Evaluation of a novel dried blood spot collection device (HemaSpot™) to test blood samples collected from dogs for antibodies to Leishmania infantum

Collection of blood samples from veterinary and wildlife patients is often challenging because the samples have to be collected on farm or in the wild under various environmental conditions. This poses many technical problems associated with venipuncture materials, their safe use and disposal, transportation and processing of collected samples. Dried blood spot (DBS) sample collection techniques offer a simple and practical alternative to traditional blood collection methods to obtain blood samples from animals for parasite antibody evaluation. The DBS collection devices are compact, simple to use, and are particularly useful for large number of samples. Additionally, DBS samples take up less space and they are easier to transport than traditional venipuncture-collected blood samples. Visceral leishmaniasis (VL) is a potentially fatal parasitic disease of dogs and humans and it is frequently diagnosed by antibody tests. Immunochromatographic tests (ICT) for antibodies to Leishmania infantum are commercially available for dogs and they produce qualitative results in minutes. Measurement of canine antibodies to L. infantum with the ICT using traditional venipuncture has been validated previously, but the use of DBS samples has not been evaluated using this method. The purpose of the present study was to determine the ability of DBS samples to detect antibodies to L. infantum in dogs using a commercial ICT assay. One hundred plasma samples from dogs experimentally infected with the LIVT-1 strain of L. infantum were collected by venipuncture and frozen. Individual samples were thawed, and then 80 μl plasma (2 drops) was aliquotted onto the 8-spoked disk pad on individual DBS sample collection devices (HemaSpot™, Spot-On Sciences, Austin, TX), dried, and stored in the dark at room temperature. After one month and six months, respectively, 2 spokes of the 8 spokes of the disk pad of each DBS sample were removed and eluted in 200 μl PBS. The eluate was used to test for antibodies in the ICT and compared to ICT results using thawed plasma (same initial source). Sensitivity and specificity of the ICT using DBS were determined by using ICT results from traditional blood collection samples for comparison. After 1 month, DBS samples showed 100% sensitivity and specificity when compared to ICT results on thawed plasma samples collected by traditional venipuncture. After six months storage at room temperature, DBS samples demonstrated 79% sensitivity and 100% specificity compared to traditional blood collection. Results from this study indicate that dried blood spot collection may be a useful tool for screening dogs for antibodies to L. infantum with the ICT assay.

Use of filter paper blood samples for rabies antibody detection in foxes and raccoon dogs

The effectiveness of oral rabies vaccination in wildlife is usually evaluated by the detection of rabies antibodies. However, the assessment of rabies antibodies has several technical difficulties in the field, such as the collection, storage, transport and titration of blood samples, often of poor quality. The objective of this study was to assess the feasibility of collecting blood on a filter paper (FP) coupled with enzyme-linked immunosorbent assay (ELISA) titration of rabies antibodies in raccoon dogs and red foxes. The FP blood sampling method was found highly specific and repeatable in both species. Overall, results obtained with the FP sampling method were highly concordant with the conventional (venipuncture) sampling methods. Blood eluates from FP samples from foxes and raccoon dogs tested using ELISA showed concordance values of 92% and 95%, respectively, with serum samples tested using the seroneutralisation test and values of 95% and 91%, respectively, when the ELISA was used on both types of sample. The use of FP blood sampling coupled with the titration of rabies antibodies by ELISA provides a reliable alternative to conventional blood sampling and serum testing by seroneutralisation. This simple procedure is particularly attractive and cost-effective for assessing the effectiveness of oral rabies vaccination in field conditions.

Serological and molecular survey of Leishmania infection in dogs from Luanda, Angola

Background

Canine leishmaniosis (CanL) due to Leishmania infantum is a global zoonosis endemic in more than 70 countries in Europe, North Africa, Asia and America; however, data on this infection is scarce from southern Africa. The aim of this study was to survey dogs in Luanda, Angola, for Leishmania infection.

Findings

One hundred-and-three dogs presented to a veterinary medical centre in Luanda were serologically and molecularly assessed for Leishmania with the direct agglutination test (DAT) and polymerase chain reaction (PCR). Two dogs were seropositive, with DAT titres of 800 and ≥6400; the latter was also found to be PCR-positive and confirmed to be infected with L. infantum by DNA sequence analysis. No other dog was found to be PCR-positive. The first dog had been imported from Portugal, but the latter had never left Angola (neither had its parents), strongly suggesting an autochthonous infection.

Conclusions

Although other cases of CanL have previously been described in the country, this is the first reported study of canine Leishmania infection at the population level, as well as the first report on the molecular characterization of L. infantum in dogs from Angola.

An overview of the clinical use of filter paper in the diagnosis of tropical diseases

Tropical infectious diseases diagnosis and surveillance are often hampered by difficulties of sample collection and transportation. Filter paper potentially provides a useful medium to help overcome such problems. We reviewed the literature on the use of filter paper, focusing on the evaluation of nucleic acid and serological assays for diagnosis of infectious diseases using dried blood spots (DBS) compared with recognized gold standards. We reviewed 296 eligible studies and included 101 studies evaluating DBS and 192 studies on other aspects of filter paper use. We also discuss the use of filter paper with other body fluids and for tropical veterinary medicine. In general, DBS perform with sensitivities and specificities similar or only slightly inferior to gold standard sample types. However, important problems were revealed with the uncritical use of DBS, inappropriate statistical analysis, and lack of standardized methodology. DBS have great potential to empower healthcare workers by making laboratory-based diagnostic tests more readily accessible, but additional and more rigorous research is needed.

Blood collected on filter paper for wildlife serology: detecting antibodies to Neospora caninum, West Nile virus, and five bovine viruses in reindeer

We compared Nobuto filter paper (FP) whole-blood samples to serum for detecting antibodies to seven pathogens in reindeer (Rangifer tarandus tarandus). Serum and FP samples were collected from captive reindeer in 2008-2009. Sample pairs (serum and FP eluates) were assayed in duplicate at diagnostic laboratories with the use of competitive enzyme-linked immunosorbent assays (cELISAs) for Neospora caninum and West Nile virus (WNV); indirect ELISA (iELISAs) for bovine herpesvirus type 1 (BHV-1), parainfluenza virus type 3 (PI-3), and bovine respiratory syncytial virus (BRSV); and virus neutralization (VN) for bovine viral diarrhea virus (BVDV) types I and II. Assay thresholds were evidence-based values employed by each laboratory. Comparable performance to serum was defined as FP sensitivity and specificity ≥ 80%. Filter-paper specificity estimates ranged from 92% in the cELISAs for N. caninum and WNV to 98% in the iELISAs for PI-3 and BRSV. Sensitivity was >85% for five tests (most ≥ 95%) but was insufficient (71-82%) for the PI-3 and BRSV iELISAs. Lowering the threshold for FP samples in these two ELISAs raised sensitivity to ≥ 87% and reduced specificity slightly (≥ 90% in three of the four test runs). Sample size limited the precision of some performance estimates. Based on the criteria of sensitivity and specificity ≥ 80%, and using adjusted FP thresholds for PI-3 and BRSV, FP sensitivity and specificity were comparable to serum in all seven assays. A potential limitation of FP is reduced sensitivity in tests that require undiluted serum (i.e., N. caninum cELISA and BVDV VNs). Possible toxicity to the assay cell layer in VN requires investigation. Results suggested that cELISA is superior to iELISA for detecting antibodies in FP samples from reindeer and other Rangifer tarandus subspecies. Our findings expand the potential utility of FP sampling from wildlife.

Risk factors for visceral Leishmaniasis among residents and migrants in Kafta-Humera, Ethiopia

Background

Visceral leishmaniasis is a lethal parasitic disease transmitted by phlebotomine sand flies. The largest focus of VL in Ethiopia is located in the lowland region bordering Sudan, where the epidemiology is complicated by the presence of thousands of seasonal agricultural workers who live under precarious conditions.

Methodology/Principal Findings

We conducted two parallel case-control studies to identify factors associated with VL risk in residents and migrants. The studies were conducted from 2009 to 2011 and included 151 resident cases and 157 migrant cases, with 2 matched controls per case. In multivariable conditional regression models, sleeping under an acacia tree at night (odds ratios (OR) 5.2 [95% confidence interval 1.7–16.4] for residents and 4.7 [1.9–12.0] for migrants), indicators of poverty and lower educational status were associated with increased risk in both populations. Strong protective effects were observed for bed net use (OR 0.24 [0.12–0.48] for net use in the rainy season among residents, OR 0.20 [0.10–0.42] for any net use among migrants). For residents, living in a house with thatch walls conferred 5-fold and sleeping on the ground 3-fold increased risk. Among migrants, the risk associated with HIV status was borderline significant and sleeping near dogs was associated with 7-fold increased risk.

Conclusions/Significance

Preventive strategies should focus on ways to ensure net usage, especially among migrant workers without fixed shelters. More research is needed to understand migration patterns of seasonal labourers and vector bionomics.

Visceral leishmaniasis is a lethal parasitic disease transmitted by sand flies. The largest focus of VL in Ethiopia is located in the lowland region bordering Sudan, where hundreds of thousands of agricultural workers migrate for work every year during the planting and harvest seasons. We conducted two parallel studies in residents and migrants to determine the living conditions and behaviors that put people at higher risk of VL risk. We found that sleeping under an acacia tree at night, indicators of poverty and lower educational status were associated with increased risk in both populations. Sleeping under a bed net was protective. For residents, living in a house with thatch walls and sleeping on the ground increased risk of VL. Among migrants, the risk associated with HIV status was borderline significant and sleeping near dogs was associated with increased risk. Preventive strategies should focus on ways to ensure net usage, especially among migrant workers without fixed shelters. More research is needed to understand migration patterns of seasonal labourers and vector behavior.

Is the dog a possible reservoir for cutaneous leishmaniasis in suriname?

Cutaneous leishmaniasis (CL) is an emerging disease in Suriname, with at least 200 cases per year. Little is known about the biology of CL in the country. The most important parasite species is Leishmania Viannia guyanensis, but possible vectors and reservoirs are hardly incriminated. In the present study, it was investigated whether the dog could possibly be a zoonotic reservoir for the disease in Suriname. Forty-seven dogs were examined for overt clinical signs of leishmaniasis, and blood samples were collected on filter paper for serology (direct agglutination test) and molecular biology (by polymerase chain reaction). Three dogs had clinical signs that could be compatible with canine cutaneous leishmaniosis: dermatitis (two) or nasal lesion (one). Two dogs were seropositive with DAT (titre > 1 : 1600), and three animals had a borderline titre (1 : 800). All other animals (n = 42) were DAT negative. PCR analysis found Leishmania DNA equivalent to 1 parasite per mL in only one dog at a first round of analysis, but this animal was negative after retesting. The clinical, serological, and molecular data show some preliminary lines of evidence that canine leishmaniosis is present in Suriname, but further studies are needed to incriminate the reservoir, including a possible sylvatic cycle.

Canine visceral leishmaniasis: seroprevalence survey of asymptomatic dogs in an endemic area of northwestern Iran

Canine visceral leishmaniasis is a major public health problem that is endemic in tropical and sub tropical countries and is fatal in humans and dogs. In addition to symptomatic dogs, asymptomatic ones seem as source of Leishmania infantum infection. Thus surveillance and control programs of reservoir hosts are essential. This study aimed to evaluate the sero-prevalence of visceral leishmaniasis in asymptomatic domestic dogs from in an endemic area of north west, Iran. A cross sectional study was carried out in Meshkin-Shahr district during 2011-2012. Blood samples collected from 508 asymptomatic domestic dogs were tested by direct agglutination test. In this study 508 dogs (397 males and 111 females, mean age, 3.24 years) from western and eastern parts of the Meshkin-Shahr were examined. A total of 508 dogs examined 119 dogs (23.4 %) had antibodies (titers of ≥1:320) against L. infantum. Statistically significance was occurred between male (25.4 %) and female (16.2) sero-prevalence (P = 0.042). No statistically significance was observed between age groups (P = 0.22). Compared with previous studies it seems to increase sero-prevalence of visceral leishmaniasis in dogs in the studied areas caused by ecological changes. High proportion of asymptomatic but seropositive dogs emphasizes the importance of dogs without clinical signs in the epidemiology of zoonotic leishmaniasis. Thus, the necessity of using serological tests in asymptomatic dogs is recommended for disease control strategy.

Evaluation of a rapid device for serological diagnosis of Leishmania infantum infection in dogs as an alternative to immunofluorescence assay and Western blotting

In this study, we compared a rapid immunochromatographic test (Speed Leish K; BVT Groupe Virbac, La Seyne sur Mer, France) with an indirect immunofluorescence assay (IFAT) and Western blotting (WB) for the detection of Leishmania infantum antibodies in dogs. A total of 250 serum samples were collected from 125 L. infantum-positive and 125 L. infantum-negative dogs. Among the positive samples, 81 were strongly positive at low IFAT dilutions, while 44 were low-reactivity sera (IFAT titers, 1:40 to 1:80). The sensitivity and specificity of the Speed Leish K were 96.3% and 100%, respectively, compared with those of the IFAT. When IFAT low-reactivity sera (titers, 1:40 or 1:80) were tested with the Speed Leish K, using WB results as a reference, the sensitivities were 93.75% for sera with a 1:80 titer and 73.33% for sera with a 1:40 titer, and the specificity was 100%. The Speed Leish K is easy to use and performs well, so it can be considered a quick and reliable tool for the diagnosis of L. infantum infection in dogs.

Evaluation of rK39 rapid diagnostic tests for canine visceral leishmaniasis: longitudinal study and meta-analysis

Background

There is a need for sensitive and specific rapid diagnostic tests (RDT) for canine visceral leishmaniasis. The aims of this study were to evaluate the diagnostic performance of immunochromatographic dipstick RDTs using rK39 antigen for canine visceral leishmaniasis by (i) investigating the sensitivity of RDTs to detect infection, disease and infectiousness in a longitudinal cohort study of natural infection in Brazil, and (ii) using meta-analysis to estimate the sensitivity and specificity of RDTs from published studies.

Methodology

We used a rK39 RDT (Kalazar Detect Canine Rapid Test; Inbios) to test sera collected from 54 sentinel dogs exposed to natural infection in an endemic area of Brazil. Dogs were sampled bimonthly for up to 27 months, and rK39 results compared to those of crude antigen ELISA, PCR, clinical status and infectiousness to sandflies. We then searched MEDLINE and Web of Knowledge (1993–2011) for original studies evaluating the performance of rK39 RDTs in dogs. Meta-analysis of sensitivity and specificity was performed using bivariate mixed effects models.

Principal Findings

The sensitivity of the rK39 RDT in Brazil to detect infection, disease and infectiousness was 46%, 77% and 78% respectively. Sensitivity increased with time since infection, antibody titre, parasite load, clinical score and infectiousness. Sixteen studies met the inclusion criteria for meta-analysis. The combined sensitivity of rK39 RDTs was 86.7% (95% CI: 76.9–92.8%) to detect clinical disease and 59.3% (37.9–77.6%) to detect infection. Combined specificity was 98.7% (89.5–99.9%). Both sensitivity and specificity varied considerably between studies.

Conclusion

The diagnostic performance of rK39 RDTs is reasonable for confirmation of infection in suspected clinical cases, but the sensitivity to detect infected dogs is too low for large-scale epidemiological studies and operational control programmes.

Canine visceral leishmaniasis is a vector-borne disease caused by the intracellular parasite Leishmania infantum. It is an important veterinary disease, and dogs are also the main animal reservoir for human infection. The disease is widespread in the Mediterranean area, and parts of Asia and South and Central America, and is potentially fatal in both dogs and humans unless treated. Diagnosis of canine infections requires serological or molecular tests. Detection of infection in dogs is important prior to treatment, and in epidemiological studies and control programmes, and a sensitive and specific rapid diagnostic test would be very useful. Rapid diagnostic tests (RDTs) have been developed, but their diagnostic performance has been reported to be variable. We evaluated the sensitivity of a RDT based on serological detection of the rK39 antigen in a cohort of naturally infected Brazilian dogs. The sensitivity of the test to detect infection was relatively low, but increased with time since infection and the severity of infection. We then carried out a meta-analysis of published studies of rK39 RDTs, evaluating the sensitivity to detect disease and infection. The results suggest that rK39 RDTs may be useful in a veterinary clinical setting, but the sensitivity to detect infection is too low for operational control programmes.

Transmission and epidemiology of zoonotic protozoal diseases of companion animals

Over 77 million dogs and 93 million cats share our households in the United States. Multiple studies have demonstrated the importance of pets in their owners' physical and mental health. Given the large number of companion animals in the United States and the proximity and bond of these animals with their owners, understanding and preventing the diseases that these companions bring with them are of paramount importance. Zoonotic protozoal parasites, including toxoplasmosis, Chagas' disease, babesiosis, giardiasis, and leishmaniasis, can cause insidious infections, with asymptomatic animals being capable of transmitting disease. Giardia and Toxoplasma gondii, endemic to the United States, have high prevalences in companion animals. Leishmania and Trypanosoma cruzi are found regionally within the United States. These diseases have lower prevalences but are significant sources of human disease globally and are expanding their companion animal distribution. Thankfully, healthy individuals in the United States are protected by intact immune systems and bolstered by good nutrition, sanitation, and hygiene. Immunocompromised individuals, including the growing number of obese and/or diabetic people, are at a much higher risk of developing zoonoses. Awareness of these often neglected diseases in all health communities is important for protecting pets and owners. To provide this awareness, this review is focused on zoonotic protozoal mechanisms of virulence, epidemiology, and the transmission of pathogens of consequence to pet owners in the United States.

Comparative study of rK39 Leishmania antigen for serodiagnosis of visceral leishmaniasis: systematic review with meta-analysis

Background

The rK39 recombinant protein is derived from a specific antigen produced by the Leishmania donovani complex, and has been used in the last two decades for the serodiagnosis of visceral leishmaniasis. We present here a systematic review and meta-analysis of studies evaluating serologic assays to diagnose visceral leishmaniasis to determine the accuracy of rK39 antigen in comparison to the use of other antigen preparations.

Methodology/Principal Findings

A systematic review with meta-analysis of the literature was performed to compare the rK39 strip-test and ELISA formats against serological tests using promastigote antigens derived from whole or soluble parasites for Direct Aglutination Test (DAT), Indirect Immunofluorescence test (IFAT) and ELISA with a promastigote antigen preparation (p-ELISA). Gold standard diagnosis was defined by the demonstration of amastigotes on hematological specimens. A database search was performed on Medline, Lilacs, Scopus, Isi Web of Science, and Cochrane Library. Quality of data was assessed using the QUADAS questionnaire. A search of the electronic databases found 352 papers of which only 14 fulfilled the selection criteria. Three evaluated the rK39 ELISA, while 13 evaluated the rK39 immunochromatographic strip test. The summarized sensitivity for the rK39-ELISA was 92% followed by IFAT 88% and p-ELISA 87%. The summarized specificity for the three diagnostic tests was 81%, 90%, and 77%. Studies comparing the rK39 strip test with DAT found a similar sensitivity of 94%, although the DAT had a slightly higher specificity. The rK39 strip test was more sensitive and specific than the IFAT and p-ELISA. We did not detect any difference in the sensitivity and specificity between strips produced by different manufacturers.

Conclusions

The rK39 protein used either in a strip test or in an ELISA, and the DAT are the best choices for implementation of rapid, easy and efficient test for serodiagnosis of VL.

Visceral Leishmaniasis (VL) is a neglected tropical disease for which serodiagnostic tests are available, but not yet widely implemented in rural areas. The rK39 recombinant protein is derived from a kinesin-like protein of parasites belonging to the Leishmania donovani complex, and has been used in the last two decades for the serodiagnosis of VL. We present here a systematic review and meta-analysis of studies evaluating serologic assays (rK39 strip-test, rK39 ELISA, Direct Agglutination Test [DAT], Indirect Immunofluorescence test [IFAT] and ELISA with a promastigote antigen preparation [p-ELISA]) to diagnose VL to determine the accuracy of rK39 antigen in comparison to the use of other antigen preparations. Fourteen papers fulfilled the inclusion and exclusion selection criteria. The summarized sensitivity for the rK39-ELISA was 92% followed by IFAT 88% and p-ELISA 87%. The summarized specificity for the three diagnostic tests was 81%, 90%, and 77%. Studies comparing the rK39 strip test with DAT found a similar sensitivity (94%) and specificity (89%). However, the rK39 strip test was more specific than the IFAT and p-ELISA. In conclusion, we found the rK39 protein used either in a strip test or in an ELISA is a good choice for the serodiagnosis of VL.