A zoonotic focus of cutaneous leishmaniasis in Addis Ababa, Ethiopia

Investigation of parasite genetic variation and systemic immune responses in patients presenting with different clinical presentations of cutaneous leishmaniasis caused by Leishmania aethiopica

BACKGROUND

Cutaneous leishmaniasis (CL) is a neglected tropical skin disease, caused by the protozoan parasite Leishmania. In Ethiopia, CL is mainly caused by Leishmania aethiopica and can present in different clinical forms. The aim of this study was to assess whether these different forms are associated with differences in parasite genetic and host systemic immune signatures.

METHODS

Here we analysed the whole genome sequence data for 48 clinical parasite isolates and the systemic immune signature from a cohort of CL patients, who were recruited in Nefas Mewcha, Northern Ethiopia, from January 2019 to January 2022.

RESULTS

Our results show that parasites from CL cases with different presentations in a single Ethiopian setting are from the same genetic population based on a permutation test of genome-wide similarity. Furthermore, a logistic regression test for genome wide association did not identify any individual genetic variants significantly associated with disease presentation. We also measured plasma chemokine and cytokine levels of 129 CL patients presenting with different forms of CL. None of the chemokine [eotaxin, eotaxin-3, interleukin (IL)-8, interferon (IFN)-γ-induced protein-10 (IP-10), monocyte chemoattractant protein (MCP)-1, MCP-4, macrophage-derived chemokines (MDC), macrophage inflammatory protein (MIP)-1α, MIP-1β and thymus- and activation-regulated chemokine (TARC)] or cytokine (IFN-γ, IL-1β, interleukin-2, IL-4, IL-6, IL-10, IL-12p70, IL-13, tumor necrosis factor-α) levels measured were significantly different between the different clinical presentations of CL, as measured by Kruskal-Wallis test. We also compared those with healthy nonendemic controls: our results show a chemokine (IP-10, MCP-1, MCP-4, MDC, MIP-1α, MIP-1β and TARC) but not a cytokine immune signature in patients with CL as compared to healthy nonendemic controls, as measured by Mann-Whitney test.

CONCLUSIONS

The results of our study did not identify a systemic immune signature or parasite genetic factors associated with different clinical presentation of CL.

Demographic characteristics and clinical features of patients presenting with different forms of cutaneous leishmaniasis, in Lay Gayint, Northern Ethiopia

Cutaneous leishmaniasis (CL) is a neglected tropical disease caused by Leishmania parasites, that can cause long-term chronic disabilities. The clinical presentation of CL varies in both type and severity. CL presents as three main clinical forms: localised lesions (localised cutaneous leishmaniasis, LCL); mucocutaneous leishmaniasis (MCL) that affects the mucosa of the nose or the mouth; or as disseminated not ulcerating nodules (diffuse cutaneous leishmaniasis, DCL). Here we recruited a cohort of CL patients in a newly established leishmaniasis treatment centre (LTC) in Lay Gayint, Northwest Ethiopia, and collected detailed demographic and clinical data. The results of our study show that more males than females present to the LTC to seek diagnosis and treatment. 70.2% of CL patients presented with LCL and 20.8% with MCL. A small number of patients presented with DCL, recidivans CL (a rare form of CL where new lesions appear on the edges of CL scars) or with a combination of different clinical presentations. The duration of illness varied from 1 month to 180 months. Over a third of CL patients had additional suspected CL cases in their household. Despite the majority of CL patients having heard about CL, only a minority knew about its transmission or that it could be treated. Most CL patients lived in areas where environmental factors known to be associated with the transmission of CL were present. This work highlights that CL is an important public health problem in Lay Gayint and emphasises the urgent need for more CL awareness campaigns, better health education and better disease management practices.

Cutaneous leishmaniasis in sub-Saharan Africa: a systematic review of Leishmania species, vectors and reservoirs

BACKGROUND

Cutaneous leishmaniasis (CL) is understudied in sub-Saharan Africa. The epidemiology of CL is determined by the species involved in its transmission. Our objectives were to systematically review available data on the species of Leishmania, along with vectors and reservoirs involved in the occurrence of human cases of CL in sub-Saharan Africa, and to discuss implications for case management and future research.

METHODS

We systematically searched PubMed, Scopus, Cochrane and African Index Medicus. There was no restriction on language or date of publication. The review was conducted according to PRISMA guidelines and was registered on PROSPERO (CRD42022384157).

RESULTS

In total, 188 published studies and 37 reports from the grey literature were included. An upward trend was observed, with 45.7% of studies published after 2010. East Africa (55.1%) represented a much greater number of publications than West Africa (33.3%). In East Africa, the identification of reservoirs for Leishmania tropica remains unclear. This species also represents a therapeutic challenge, as it is often resistant to meglumine antimoniate. In Sudan, the presence of hybrids between Leishmania donovani and strictly cutaneous species could lead to important epidemiological changes. In Ghana, the emergence of CL in the recent past could involve rare species belonging to the Leishmania subgenus Mundinia. The area of transmission of Leishmania major could expand beyond the Sahelian zone, with scattered reports in forested areas. While the L. major-Phlebotomus duboscqi-rodent complex may not be the only cycle in the dry areas of West Africa, the role of dogs as a potential reservoir for Leishmania species with cutaneous tropism in this subregion should be clarified. Meglumine antimoniate was the most frequently reported treatment, but physical methods and systemic agents such as ketoconazole and metronidazole were also used empirically to treat L. major infections.

CONCLUSIONS

Though the number of studies on the topic has increased recently, there is an important need for intersectional research to further decipher the Leishmania species involved in human cases of CL as well as the corresponding vectors and reservoirs, and environmental factors that impact transmission dynamics. The development of molecular biology in sub-Saharan Africa could help in leveraging diagnostic and research capacities and improving the management of human cases through personalized treatment strategies.

Case Notification of Cutaneous Leishmaniasis at Different Elevations in the North-Central Ethiopia from 2018 To 2022

Background

We aimed to analyze a four-year trend of Cutaneous leishmaniasis (CL) to determine risk levels and hotspots in North-central Ethiopia.

Methods

This retrospective study was conducted at Boru Meda Hospital (BMH) from March to April 2023, focusing on CL patients treated at the leishmaniasis treatment center (LTC). Data collected included age, gender, CL type, and other clinical factors. Each patient's origin was traced and geographically mapped by elevation to assess CL risk levels.

Results

There were a total of 573 CL patients reported from 46 districts, with a higher number of male patients (n=356) compared to female patients (n=217) (P <0.001). The median age of the patients was 21 years [15-30], with the highest number of CL cases observed among individuals aged 16 to 30 years. The majority of cases (69%) presented with localized CL (LCL). About 39% of patients had a previous treatment history for CL. A significant clustering of CL cases was observed at elevation of 2301-3300 meters above sea level (χ2:17.5; P <0.001), with the highest incidence (case notification) of 14.2/100,000 population.

Conclusion

Foci of CL, were burdened at higher elevations and no clinical variation were observed between elevation differences. The majority of cases were concentrated in an area covering approximately 21.4% of the total land mass. CL continues to be a significant issue in North-central Ethiopia and has the potential to spread to new areas.

Treatment outcomes of cutaneous leishmaniasis due to Leishmania aethiopica: A systematic review and meta-analysis

BACKGROUND

Leishmania aethiopica is a unique species that causes cutaneous leishmaniasis (CL), and studies evaluating treatment outcomes for this condition reported inconsistent findings. This study aimed to summarize the evidence on treatment outcomes of CL caused by L. aethiopica to support decisions or propose further study.

METHODS

We searched PubMed, Scopus, and ScienceDirect. In addition, we searched grey literature on Google Scholar and performed manual searching on the reference list of articles. Two authors did the screening, selection, critical appraisal, and data extraction. With the narrative synthesis of evidence, we performed a random effects model meta-analysis using the metaprop package in Stata 17. We did sensitivity and subgroup analyses after assessing heterogeneity using the I-squared test and forest plots. The funnel plot and Egger's test were used to assess publication bias.

RESULTS

The review included 22 studies with 808 participants, and the meta-analysis included seven studies with 677 participants. Most studies documented treatment outcomes with antimonial monotherapy, and only one study reported outcomes with combination therapy. The overall pooled proportion of cure was 63% (95% CI: 38-86%). In the subgroup analysis, systemic antimonial monotherapy showed a cure rate of 61%, and the proportion of cure was 87% with topical therapy. Topical therapy showed a better cure for the localized clinical phenotype. A cohort study documented a cure rate of 94.8% with combination therapy for the localized, mucocutaneous, and diffuse clinical phenotypes. The pooled proportion of unfavourable outcomes was partial response (19%), relapse (17%), discontinuation (19%), and unresponsiveness (6%).

CONCLUSIONS

The pooled proportion of cure is low with antimonial monotherapy. Despite limited evidence, combination therapies are a promising treatment option for all clinical phenotypes of CL caused by L. aethiopica. Future high-quality randomized control trials are needed to identify effective monotherapies and evaluate the effectiveness of combination therapies.

Cutaneous leishmaniasis in Kutaber District, Ethiopia: Prevalence, sand fly fauna and community knowledge, attitude and practices

Background

Cutaneous leishmaniasis (CL) affects 25% of the population living in the highlands of Ethiopia. CL intervention has not decreased the number of leishmaniasis patients. A cross-sectional study was conducted to determine CL prevalence, community's knowledge, attitude and practices (KAP), and the sand fly fauna in Kutaber district, northeast Ethiopia.

Methods

A retrospective, community-based cross-sectional study was conducted in Boru Meda Hospital from December 2014-March 2021 to study CL prevalence of Kutaber district. A Pre-tested, well-structured questionnaire was used to collect data on the participants' socio-demographic characteristics, KAP towards CL and knowledge about sand fly vectors. Chi-square test and logistic regression analysis were used in the study, and data were analyzed using SPSS version 23 (p < 0.05).

Results

A total of 10,002 (14.02%), of which 71,325 samples were confirmed as positive for CL. The infection rate of CL in females (7.1%) was a little bit higher than males (7.0%). More cases were recorded among 15-29 age category. The study also revealed that 77.1% of the respondents had poor knowledge about CL treatment, prevention, clinical presentation and disease transmission. Farmers tended to have poorer knowledge about sand flies than non-workers and students (32.7 vs. 35 and 44.1%; P = 0.049). Housewives had poorer knowledge about sand flies than farmers and workers (22.2 vs. 32.7 and 33.3%; P = 0.023). Phlebotomus longipes comprised the highest composition (80%) of the sand fly species identified in Kutaber district.

Conclusions

The data showed that the community had poor knowledge about CL, vector, and transmission mode. CL preventive measures were prevalent, implying the need to raise CL awareness. Phlebotomus longipes was identified as the most dominant sand fly species which accounted for CL. The findings can be used in developing an effective control strategy to reduce CL transmission in the study area and elsewhere in Ethiopia.

Chromosome-Scale Assembly of the Complete Genome Sequence of Leishmania (Mundinia) procaviensis Isolate 253, Strain LV425

Leishmania (Mundinia) procaviensis is a parasitic kinetoplastid that was first isolated from a rock hyrax in Namibia in 1975. We present the complete genome sequence of Leishmania (Mundinia) procaviensis isolate 253, strain LV425, sequenced using combined short- and long-read technologies. This genome will contribute to our understanding of hyraxes as a Leishmania reservoir.

Phlebotomine sandflies (Diptera: Psychodidae) of Ethiopia

Phlebotomine sandflies have a long history of association with humans, which makes them the only proven natural vectors of Leishmania species, the parasitic protozoans that cause leishmaniases in humans and animals. In Ethiopia, the three forms of leishmaniases, viz., visceral, dermal and mucocutaneous are endemic in different parts of the country. Since the first report of phlebotomine sandflies in Ethiopia in 1936, the distribution of different species and their role in the transmission of leishmaniases have been extensively studied. The objective of this review was to summarize the patchy information and give an updated list of phlebotomine sandfly species in Ethiopia and their known geographical distribution in the country. Peer-reviewed literature search was conducted using online databases. All articles published which focus on distribution and medical importance of Phlebotomus and Sergentomyia species of Ethiopia starting from 1936 up to 2022 were reviewed. Until July 2022, 65 phlebotomine sandfly species have been reported, belonging to the genus Phlebotomus and Sergentomyia. The genus Phlebotomus in Ethiopia is represented by six subgenera such as Adlerius, Anaphlebotomus, Larroussius, Paraphlebotomus Phlebotomus and Synphlebotomus, whereas the genus Sergentomyia is represented by six subgenera, namely Grassomyia, Parrotomyia, Parvidens, Rondanomyia, Sergentomyia, and Sintonius.

Knowledge, attitude, and practice of the rural community about cutaneous leishmaniasis in Wolaita zone, southern Ethiopia

BACKGROUND

Cutaneous leishmaniasis (CL) is a neglected tropical disease that is caused by a Leishmania parasite and transmitted by the bite of infected female sandflies. Community awareness is an essential component of disease control and prevention. Therefore, this study aimed to assess the community's knowledge, attitude, and practice toward CL in Wolaita zone, southern Ethiopia.

METHODS

A community-based cross-sectional study design was employed to include 422 study subjects selected using a systematic sampling technique from two districts, Kindo Didaye and Sodo Zuria. A pretested structured questionnaire was used to collect data from the household heads. Bivariate and multivariate logistic regression analyses were performed to determine the relationship between the participants' knowledge about CL and socio-demographic characteristics.

RESULTS

Out of the 422 study participants, only 19% had good knowledge of CL in general. Most (67.1%) of the respondents knew CL by its local name ("bolbo" or "moora") though this knowledge varied highly over the study districts. The majority (86.3%) of respondents did not know how CL is acquired, though they considered CL a health problem. Most (62.8%) respondents believed that CL was an untreatable disease. Most (77%) participants responded that CL patients preferred to go to traditional healers for treatment. Herbal treatment was the most (50.2%) used to treat CL. Knowledge about CL was significantly associated with sex, age, and study districts.

CONCLUSION

The overall knowledge, attitude, and practice about CL and its prevention in the study area were low. This emphasizes the need to implement health education and awareness campaign to reduce the risk of CL infection. Policymakers and stakeholders should also give due attention to the prevention and treatment of CL in the study area.

Evaluation of the CL Detect Rapid Test in Ethiopian patients suspected for Cutaneous Leishmaniasis

Background

Cutaneous leishmaniasis (CL) is common in Ethiopia, mainly affecting impoverished populations in rural areas with poor access to health care. CL is routinely diagnosed using skin slit smear microscopy, which requires skilled staff and appropriately equipped laboratories. We evaluated the CL Detect Rapid Test (InBios, Washington, USA), which is supplied with a dental broach sampling device, as a diagnostic alternative which could be used in field settings.

Methodology/Principal findings

We evaluated the diagnostic accuracy of the CL Detect Rapid Test on skin slit and dental broach samples from suspected CL patients at the Leishmaniasis Research and Treatment Center in Gondar, Ethiopia. A combined reference test of microscopy and PCR on the skin slit sample was used, which was considered positive if one of the two tests was positive. We recruited 165 patients consecutively, of which 128 (77.6%) were confirmed as CL. All microscopy-positive results (n = 71) were also PCR-positive, and 57 patients were only positive for PCR. Sensitivity of the CL Detect Rapid Test on the skin slit was 31.3% (95% confidence interval (CI) 23.9–39.7), which was significantly higher (p = 0.010) than for the dental broach (22.7%, 95% CI 16.3–30.6). Sensitivity for both methods was significantly lower than for the routinely used microscopy, which had a sensitivity of 55.5% (IQR 46.8–63.8) compared to PCR as a reference.

Conclusions/Significance

The diagnostic accuracy of the CL Detect Rapid Test was low for skin slit and dental broach samples. Therefore, we do not recommend its use neither in hospital nor field settings.

Trial registration

This study is registered at ClinicalTrials.gov as NCT03837431.

Cutaneous leishmaniasis (CL) is common in Ethiopia, and mainly affects rural areas with poor access to health care. CL is routinely diagnosed using microscopy on a skin slit sample, which requires skilled staff and appropriately equipped laboratories. We evaluated the diagnostic accuracy of the CL Detect Rapid Test as an alternative which could be used in field settings. In a population of 165 patients suspected to have CL, 78% was confirmed to have CL by PCR. We found that the CL Detect Rapid Test on the supplied dental broach had a sensitivity of only 23%; on a skin slit sample, the Rapid Test had a slightly higher sensitivity with 31%. The routine diagnostic test of microscopy on the skin slit had a significantly higher sensitivity with 56%. These findings show that the sensitivity of the CL Detect Rapid Test is low, and is much worse than that of the currently used diagnostic method. Therefore, we do not recommend it to be used for diagnosing CL in Ethiopia.

Household knowledge, practice and treatment seeking behaviors towards cutaneous leishmaniasis in the endemic rural communities of Ganta- afeshum district, Tigrai, northern Ethiopia, 2019: a cross-sectional study

BACKGROUND

Cutaneous leishmaniasis is endemic to Ethiopia. However, the prevention and control efforts of leishmaniasis remain unfocused with clear knowledge and practice gaps within the country. Thus, a house to house survey has been carried out to assess the knowledge, practice and treatment-seeking behavior of households towards cutaneous leishmaniasis in the rural communities of Tigrai region, northern Ethiopia.

METHODS

A community-based cross-sectional house-to-house survey was conducted in two selected rural villages of Ganta-afeshum district, Tigrai, northern Ethiopia in 2019. A simple random sampling technique was employed to select the participants. Household heads were interviewed using a pre-tested semi-structured questionnaire. Epi info version 7.0 was used for data entry and the data were imported to SPSS version 23 for analysis. Chi-square test (χ2) was used to test the association between the independent variables and the knowledge and practice status of the study participants. P-value < 0.05 was used to declare a statistically significant association among the variables.

RESULTS

In our study, most of the participants (78%) stated that cutaneous leishmaniasis is a health problem in the area. Three hundred eighty (99.5%) participants responded that the most common clinical presentation of cutaneous leishmaniasis is a lesion on the face. All of the study participants did not know the mode of cutaneous leishmaniasis transmission, and had never heard of the sand fly. A majority of the participants were unaware of the main prevention methods for cutaneous leishmaniasis. Lastly, traditional medicine was used in 90% of the study households with a previous history for cutaneous leishmaniasis.

CONCLUSION

There is a lack of awareness regarding the transmission of cutaneous leishmaniasis in Ganta-afeshum, Ethiopia, where the majority of individuals are unfamiliar with the sand fly vector. Prevention methods for cutaneous leishmaniasis were unavailable among the community. Therefore, health education programs concerning cutaneous leishmaniasis transmission, prevention, and treatment in the area should be rigorously implemented.

Leishmaniasis Beyond East Africa

Climate change is having a substantial impact on our environment and ecosystems and has altered the way humans live, access, and utilize resources with increased risk of zoonotic infectious disease encounters. As global temperatures continue to increase, they impact on public health, migration, food security and land conflict, and as new environments become favorable, exposure to disease carrying vectors. Increased forests or natural habitat clearance for land repurposing, urbanization, road building, and water management are related to an increase in emerging vector borne parasitic diseases. The East African region remains one of the most impacted regions globally for leishmaniasis, a vector borne disease that impacts significantly on the health, wellbeing and livelihoods of affected communities and for which a lack of reporting and control interventions hinder progress toward elimination of this neglected tropical disease. As our world continues to transform, both politically and climatically, it is essential that measures are put in place to improve surveillance and disease management with implementation of control measures, including vector control, especially in low- and middle-income countries that are expected to be most impacted by changes in climate. Only through effective management, now, can we be sufficiently resilient to preventing the inevitable spread of vectors into suitable habitat and expansion of the geographical range of leishmaniasis. This review offers a current perspective on Leishmaniasis as an endemic disease in East Africa and examines the potential of the recent emergence of Leishmania infection in hitherto unaffected regions to become a public health concern if no disease management is achieved.

Demography and determinants of dog and cat ownership in three towns of West Shoa zone, Oromia Region, Ethiopia

BACKGROUND

The dog and cat population data is generally scarce in developing countries due to absence of surveys. The demography of owned dogs and cats, and the associated ownership characteristics, are essential for the control of pet population and zoonosis. This study was conducted in three towns of West Shoa Zone of Ethiopia with the objectives of assessing demographic characteristics of owned dogs and cats and determinants of ownership.

RESULTS

About 65.1% (95% CI: 62.1-69.8%) of the householders own dogs, 39.2% (95% CI: 35.8-43.8%) own cats, and 30.6% (95% CI: 27.4-35.0%) own both. The majority of the dog-owning households own a single dog (74.8%) and cat (74.9%). There were significantly higher proportion of dog and cat-owning households in Bako than Ambo and Gojo towns. The human to owned-dog ratio was 6:1, and that of cat ratio was 10:1. There were more male dogs (72.1%) and more female cats (59.7%). The male to female sex ratio was estimated at 3:1 for the dog while nearly 1:1 for cats. About 37.5% of the owned dogs were indoor, and 62.5% have free access to outside. Dogs and cats were acquired as a gift from families, neighbors, and friends. The identified reason for not owning dogs/cats were fear of zoonosis, dislike, no time to devote, benefit not realized, and shortage of finance. Logistic regression analysis identified study town, community type, gender of head of household, ownership of other animals as determinants for dog/cat ownership. Besides, possessing dogs was significantly associated with cat ownership.

CONCLUSION

The current study provide insights into the determinants of dogs/cats ownership and their demographic characteristics in Ethiopia. Dogs are more commonly owned, but the household determinants for dog and cat ownership were comparable. Means of obtaining and reason of owning or abandoning dogs/cats is partly different from those reported in the developed countries. The results of this study could be used for the provision of veterinary services, quantifying health risks and benefits associated with dog/cat ownership, and control of pet population and related zoonosis.

An integrative approach to identify sand fly vectors of leishmaniasis in Ethiopia by morphological and molecular techniques

Background

Ethiopia is affected by human leishmaniasis caused by several Leishmania species and transmitted by a variety of sand fly vectors of the genus Phlebotomus. The sand fly fauna in Ethiopia is highly diverse and some species are closely related and similar in morphology, resulting in difficulties with species identification that requires deployment of molecular techniques. DNA barcoding entails high costs, requires time and lacks reference sequences for many Ethiopian species. Yet, proper species identification is pivotal for epidemiological surveillance as species differ in their actual involvement in transmission cycles. Recently, protein profiling using MALDI-TOF mass spectrometry has been introduced as a promising technique for sand fly identification.

Methods

In our study, we used an integrative taxonomic approach to identify most of the important sand fly vectors of leishmaniasis in Ethiopia, applying three complementary methods: morphological assessment, sequencing analysis of two genetic markers, and MALDI-TOF MS protein profiling.

Results

Although morphological assessment resulted in some inconclusive identifications, both DNA- and protein-based techniques performed well, providing a similar hierarchical clustering pattern for the analyzed species. Both methods generated species-specific sequences or protein patterns for all species except for Phlebotomus pedifer and P. longipes, the two presumed vectors of Leishmania aethiopica, suggesting that they may represent a single species, P. longipes Parrot & Martin. All three approaches also revealed that the collected specimens of Adlerius sp. differ from P. (Adlerius) arabicus, the only species of Adlerius currently reported in Ethiopia, and molecular comparisons indicate that it may represent a yet undescribed new species.

Conclusions

Our study uses three complementary taxonomical methods for species identification of taxonomically challenging and yet medically import Ethiopian sand flies. The generated MALDI-TOF MS protein profiles resulted in unambiguous identifications, hence showing suitability of this technique for sand fly species identification. Furthermore, our results contribute to the still inadequate knowledge of the sand fly fauna of Ethiopia, a country severely burdened with human leishmaniasis.

High-resolution habitat suitability model for Phlebotomus pedifer, the vector of cutaneous leishmaniasis in southwestern Ethiopia

BACKGROUND

Phlebotomus pedifer is the vector for Leishmania aethiopica causing cutaneous leishmaniasis (CL) in southwestern Ethiopia. Previous research on the transmission dynamics of CL resulted in recommendations for vector control. In order to target these interventions towards affected areas, a comprehensive understanding of the spatial distribution of P. pedifer at high spatial resolution is required. Therefore, this study determined the environmental predictors that facilitate the distribution of P. pedifer and created a map indicating the areas where conditions are suitable for survival of the vector in southwestern Ethiopia with high spatial resolution.

METHODS

Phlebotomus pedifer presence points were collected during two entomological surveys. Climate, vegetation and topographic variables were assembled. Climate variables were interpolated with variables derived from high-resolution digital elevation models to generate topoclimatic layers representing the climate conditions in the highlands. A Maximum Entropy model was run with the presence points, predicting variables and background points, which were selected based on a bias file.

RESULTS

Phlebotomus pedifer was the only captured Phlebotomus species in the study area and was collected at altitudes ranging between 1685 and 2892 m. Model projections indicated areas with suitable conditions in a 'belt' surrounding the high mountain peaks. Model performance was high, with train and test AUC values being 0.93 and 0.90, respectively. A multivariate environmental similarity surface (MESS) analysis showed that the model projection was only slightly extrapolated for some of the variables. The mean annual temperature was the environmental variable, which contributed most to the model predictions (60.0%) followed by the seasonality in rainfall (13.2%). Variables representing steep slopes showed very low importance to model predictions.

CONCLUSIONS

Our findings indicate that the suitable habitats for P. pedifer correspond well with the altitudes at which CL was reported previously, but the predictions are more widely distributed, in contrast with the description of CL to occur in particular foci. Moreover, we confirm that vector distribution is driven by climate factors, suggesting inclusion of topoclimate in sand fly distribution models. Overall, our model provides a map with a high spatial resolution that can be used to target sand fly control measures in southwestern Ethiopia.

Cutaneous leishmaniasis in north-central Ethiopia: trend, clinical forms, geographic distribution, and determinants

Background

Cutaneous leishmaniasis (CL), being among the neglected tropical diseases, catches little attention despite its considerable influence. This study aimed at estimating the prevalence and associated factors of CL in Boru Meda Hospital, Dessie town, north-central Ethiopia.

Methods

Medical records of patients who attended the Dermatology Department of the Hospital in 2012-May 2018 were assessed. In addition, dermatological patients who were visiting the hospital during the data collection period (November 2017-May 2018) were interviewed to capture socio-demographic, environmental variables, and related factors. The source population was individuals who visited the hospital for skin problems in the stated years and CL positives were the targets. The association between CL and its determinants was tested by logistic regression.

Results

CL prevalence was 1.5% showing increasing trend with the year of examination. Localized, diffused, and mucosal CL was evident across the years. Dessie town had the highest prevalence, 291 (32.8%) patients out of 888 cases. The number of examined (29,701) and positives (543, 1.8%) for males was comparable with females, 28,459 and 345 (1.2%), respectively, increasing with age but without significant difference. Dessie town residence (adjusted odds ratio (AOR) 12.2, 95% confidence interval (CI) 2.2-18.6, p = 0.01), no bed net (AOR 9.9, 95% CI 2.7-16.7, p < 0.01), nearby irrigation (AOR 8.1, 95% CI 1.9-12.4, p < 0.01), and travel to CL endemic areas (AOR 13.9, 95% CI 4.4-14.3, p < 0.01) were significantly associated with CL.

Conclusion

CL is a growing health problem in Dessie and its surroundings. Known risk factors prevail. Comprehensive parasitological, entomological, and social studies are warranted to better manage the disease.

Evaluation of a pan-Leishmania SL RNA qPCR assay for parasite detection in laboratory-reared and field-collected sand flies and reservoir hosts

Background

In eco-epidemiological studies, Leishmania detection in vectors and reservoirs is frequently accomplished by high-throughput and sensitive molecular methods that target minicircle kinetoplast DNA (kDNA). A pan-Leishmania SYBR green quantitative PCR (qPCR) assay which detects the conserved spliced-leader RNA (SL RNA) sequence was developed recently. This study assessed the SL RNA assay performance combined with a crude extraction method for the detection of Leishmania in field-collected and laboratory-reared sand flies and in tissue samples from hyraxes as reservoir hosts.

Methods

Field-collected and laboratory-infected sand fly and hyrax extracts were subjected to three different qPCR approaches to assess the suitability of the SL RNA target for Leishmania detection. Nucleic acids of experimentally infected sand flies were isolated with a crude extraction buffer with ethanol precipitation and a commercial kit and tested for downstream DNA and RNA detection. Promastigotes were isolated from culture and sand fly midguts to assess whether there was difference in SL RNA and kDNA copy numbers. Naive sand flies were spiked with a serial dilution of promastigotes to make a standard curve.

Results

The qPCR targeting SL RNA performed well on infected sand fly samples, despite preservation and extraction under presumed unfavorable conditions for downstream RNA detection. Nucleic acid extraction by a crude extraction buffer combined with a precipitation step was highly compatible with downstream SL RNA and kDNA detection. Copy numbers of kDNA were found to be identical in culture-derived parasites and promastigotes isolated from sand fly midguts. SL RNA levels were slightly lower in sand fly promastigotes (ΔCq 1.7). The theoretical limit of detection and quantification of the SL RNA qPCR respectively reached down to 10⁻³ and 10 parasite equivalents. SL RNA detection in stored hyrax samples was less efficient with some false-negative assay results, most likely due to the long-term tissue storage in absence of RNA stabilizing reagents.

Conclusions

This study shows that a crude extraction method in combination with the SL RNA qPCR assay is suitable for the detection and quantification of Leishmania in sand flies. The assay is inexpensive, sensitive and pan-Leishmania specific, and accordingly an excellent assay for high-throughput screening in entomological research.

Feeding behavior and activity of Phlebotomus pedifer and potential reservoir hosts of Leishmania aethiopica in southwestern Ethiopia

BACKGROUND

Cutaneous leishmaniasis (CL) is a major public health concern in Ethiopia. However, knowledge about the complex zoonotic transmission cycle is limited, hampering implementation of control strategies. We explored the feeding behavior and activity of the vector (Phlebotomus pedifer) and studied the role of livestock in CL transmission in southwestern Ethiopia.

METHODS

Blood meal origins of engorged sand flies were determined by sequencing host DNA. A host choice experiment was performed to assess the feeding preference of P. pedifer when humans and hyraxes are equally accessible. Ear and nose biopsies from livestock were screened for the presence of Leishmania parasites. Sand flies were captured indoor and outdoor with human landing catches and CDC light traps to determine at which time and where P. pedifer is mostly active.

PRINCIPAL FINDINGS

A total of 180 P. pedifer sand flies were found to bite hosts of 12 genera. Humans were the predominant blood meal source indoors (65.9%, p < 0.001), while no significant differences were determined outdoors and in caves. In caves, hyraxes were represented in blood meals equally as humans (45.5% and 42.4%, respectively), but the host choice experiment revealed that sand flies have a significant preference for feeding on hyraxes (p = 0.009). Only a single goat nose biopsy from 412 animal samples was found with Leishmania RNA. We found that P. pedifer is predominantly endophagic (p = 0.003), but occurs both indoors and outdoors. A substantial number of sand flies was active in the early evening, which increased over time reaching its maximum around midnight.

CONCLUSION

In contrast to earlier suggestions of exclusive zoonotic Leishmania transmission, we propose that there is also human-to-human transmission of CL in southwestern Ethiopia. Livestock does not play a role in CL transmission and combined indoor and outdoor vector control measures at night are required for efficient vector control.

The effects of climate change on human health in Africa, a dermatologic perspective: a report from the International Society of Dermatology Climate Change Committee

Throughout much of the African continent, healthcare systems are already strained in their efforts to meet the needs of a growing population using limited resources. Climate change threatens to undermine many of the public health gains that have been made in this region in the last several decades via multiple mechanisms, including malnutrition secondary to drought-induced food insecurity, mass human displacement from newly uninhabitable areas, exacerbation of environmentally sensitive chronic diseases, and enhanced viability of pathogenic microbes and their vectors. We reviewed the literature describing the various direct and indirect effects of climate change on diseases with cutaneous manifestations in Africa. We included non-communicable diseases such as malignancies (non-melanoma skin cancers), inflammatory dermatoses (i.e. photosensitive dermatoses, atopic dermatitis), and trauma (skin injury), as well as communicable diseases and neglected tropical diseases. Physicians should be aware of the ways in which climate change threatens human health in low- and middle-income countries in general, and particularly in countries throughout Africa, the world's lowest-income and second most populous continent.

Prevalence and environmental determinants of cutaneous leishmaniasis in rural communities in Tigray, northern Ethiopia

Background

In Ethiopia guidelines for diagnoses and treatment of leishmaniases are available, but only a few hundred people are diagnosed and receive treatment. A field study has been carried out to determine the status and environmental determinants of cutaneous leishmaniasis (CL) and assess the degree of awareness of the rural communities in affected areas in Tigray, northern Ethiopia.

Methodology / Principal findings

Following a reconnaissance survey that identified endemic foci, a cross sectional door-to-door survey was conducted in 2009 in five rural communities around the towns of Adigrat and Hagereselam in Tigray. In total 9,622 residents of 1,721 households were clinically screened and household heads interviewed regarding the determinants of infection. The χ² test and logistic regression were used to determine differences in prevalence between localities, age and sex, and to identify environmental determinants of infection.

The overall prevalence of localized CL was 2.3% (highest 4.7%), with marked inter-village differences. Another 20.9% had scars from previous infections. While risk was sex-independent, prevalence was significantly higher in the 0–9 (4.5%) and 10–19 (2.5%) age groups and predominantly involved the face (82.1%) and upper limbs (13.1%). Nearly 11% of the households had one or more cases of CL and this was associated with proximity to hyrax habitats. All interviewees were knowledgeable about the lesions but ignorant of the disease’s mode of transmission and its association with hyraxes.

Conclusions

The study established that CL is an important public health problem in the study communities, and has been so for a while, as demonstrated by the widespread presence of scars. CL in Tigray appeared to be predominantly of zoonotic nature, mainly transmitted in peri-domestic habitats in proximity to hyrax habitats. Integrated interventions, including awareness creation, are highly recommended.

Cutaneous leishmaniasis (CL) is a skin infection, transmitted by sandflies. It is most common in Ethiopia, but so far only a few hundred people have received treatment. Five rural villages in Tigray Region, in the north of Ethiopia, were visited to assess the status and determinants of CL. In a door-to-door survey 9,622 residents of 1,721 households were examined and interviewed. A total of 222 had active lesions, an average prevalence of 2.3% CL. Children (up to 9 years old) and teenagers (age 10–19) were more affected than other groups. Most active lesions were found in the face and on arms. Almost 11% of the households had one or more cases of CL and this was associated with proximity to habitats of hyrax, intermediate hosts of the disease. A total of 2009 people (20.9%) showed scars from earlier infections. The findings show how widespread the disease is in the north of Ethiopia and provide some first insights into the environmental factors that influence transmission.

Demographical and population dynamics impact on public health of cutaneous Leishmaniasis in Al-Madinah Almonawra, Saudi Arabia

Background

A cross-sectional study conducted in Al-Madinah Almonawra in KSA held during the period from March 2014–March 2015.

Aim of the study

This study aimed at analyzing the effect of population dynamics on the current situation of cutaneous leishmaniasis in Al-Madinah Almonawarah area, a holy city that attracts millions of muslims annually.

Methodology

Epidemiological and clinical data were collected by especial questionnaire and laboratory specimens were collected using skin scraping and needle aspiration. Staining and direct microscopy were done. LST was conducted. Analysis was done using SPSS program.

Results

The study included 164 patients, all of them were men. Saudi nationality comprised around 20% of the study group, the majority were Egyptians, 26.2%, followed by Pakistani, 21.3%.

Conclusion

The presence of non-Saudi nationality as foreign workers, immigrants and refugees has worsened the current situation of the disease.

Ecology and seasonality of sandflies and potential reservoirs of cutaneous leishmaniasis in Ochollo, a hotspot in southern Ethiopia

Background

Ochollo is a village in southern Ethiopia burdened with cutaneous leishmaniasis (CL), where Phlebotomus pedifer is the only vector for Leishmania aethiopica and hyraxes are confirmed reservoir hosts. A detailed description of the different players of transmission, and the ecology and seasonality of the vector needs to be established in order to accomplish efficient control programs.

Methods and findings

Between March 2017 and February 2018, a monthly sandfly collection was carried out in different habitats and records of temperature and humidity were taken. Rodents and hyraxes were trapped in the dry and wet season. All samples were screened for Leishmania kinetoplast DNA (kDNA). Positive samples were further processed for determination of the Leishmania species and the species of the sandfly/small mammal that was found infected. Additionally, the species of 400 sandfly specimens from different habitats and seasons was identified.

17,190 Sergentomyia and Phlebotomus sandflies were caught and showed an overall kDNA prevalence of 2.6%, all were L. aethiopica infections only found in P. pedifer. The overall sandfly and P. pedifer abundance peaked in the dry season and was negatively correlated with the %RH. The kDNA prevalence varied over the months and was negatively correlated with the temperature. Total sandfly abundance did not differ between the sampled habitats, but P. pedifer was the distinct predominant species only in caves. Moreover, significantly more infected sandflies were found in caves. Only 1/192 rodents were kDNA positive, while 20.0% (5/25) of Heterohyrax brucei were found infected.

Conclusions

This study suggests that caves may be a source of multiplication of the infection. If an outdoor control program would be considered, it would be useful to focus on caves in the wet season, when the sandfly abundance is lowest. The captured rodent species appear not important for transmission and the contribution of hyraxes in transmission should be further investigated.

Zoonotic cutaneous leishmaniasis poses a considerable health problem in Ethiopia. Efficient disease control can only be accomplished when all players of transmission are well understood and taken into account. The aim of our study was to investigate in a village in the south, called Ochollo, whether rodents also harbor the parasite and to assess the different potential vector species (sandflies) and their spatial and seasonal distribution. We established that the rodent species we captured are probably no hosts for Leishmania aethiopica, but confirmed that hyraxes are abundant and that a high percentage of them is positive for L. aethiopica. Based on a very large sample size, we found that Phlebotomus pedifer is the only vector in the area. We discovered that the general sandfly and specific P. pedifer abundance are lowest in the wet season and negatively correlated with humidity. We also demonstrated that the sandfly abundance is equally distributed among different habitats, but P. pedifer and infected sandflies mainly reside in caves. Altogether, we suggest that if outdoor sandfly control methods would be considered, it would be useful to carry it out in the wet season in or around caves. The role of hyraxes in disease transmission should be further investigated.

Cutaneous Leishmaniasis Due to Leishmania aethiopica

Leishmania aethiopica is the main causative species for cutaneous leishmaniasis (CL) in Ethiopia. Despite its considerable burden, L. aethiopica has been one of the most neglected Leishmania species. In this review, published evidence on L. aethiopica history, geography, vector, reservoir, epidemiology, parasitology, and immunology is discussed and knowledge gaps are outlined. L. aethiopica endemic regions are limited to the highland areas, although nationwide studies on CL prevalence are lacking. Phlebotomus pedifer and P. longipes are the sandfly vectors and hyraxes are considered to be the main reservoir, but the role of other sandfly species and other potential reservoirs requires further investigation. Where and how transmission occurs exactly are also still unknown. Most CL patients in Ethiopia are children and young adults. Lesions are most commonly on the face, in contrast to CL caused by other Leishmania species which may more frequently affect other body parts. CL lesions caused by L. aethiopica seem atypical and more severe in their presentation as compared to other Leishmania species. Mucocutaneous leishmaniasis and diffuse cutaneous leishmaniasis are relatively common, and healing of lesions caused by L. aethiopica seems to take longer than that of other species. A thorough documentation of the natural evolution of L. aethiopica as well as in depth studies into the immunological and parasitological characteristics that underpin the atypical and severe clinical presentation are needed. Better understanding of CL caused by this parasite species will contribute to interventions related to transmission, prevention, and treatment.

Zoonotic impact and epidemiological changes of leishmaniasis in Ethiopia

Leishmaniasis is one of the growing public health challenges in Ethiopia and estimated over 7,000 and 50,000 new cases of visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL) per year, respectively. The aim of the review is to address zoonotic impact and epidemiological changes of leishmaniasis in Ethiopia. VL is caused by L. donovani and it is endemic in many parts of the country with one third of the country’s landmass is highly suitable for VL. CL is principally caused by L. aethiopica. CL is endemic and widespread in the highland of Ethiopia. Northern lowland foci are Humera and Metema plains in the Tigray and Amhara regional states constitute the main VL endemic areas in the country, contributing over 60% of the total burden. The southern foci are the south-western savannah, and the south-eastern semi-arid lowlands which account for approximately 20 % of the total VL burden in Ethiopia. Leishmaniasis is a serious zoonotic disease in Ethiopia with more reservoir hosts maintaining the disease. Dogs and hyraxes are the main reservoir hosts for visceral and cutaneous leishmaniasis in the country, respectively. Epidemiological changes of leishmaniasis may relate to environmental changes and expansion of mega projects such as irrigations and sugar cane factories, knowledge and socio-economic factors, development of new settlements, migration of peoples and HIV/AIDS co-infection. Expansions of mega projects such as sugar factories and irrigations are suitable for reproduction of stray dogs, rodents, wild canids and vectors. VL is one of the major challenges to prevent and control in the endemic areas of the country. Therefore, new research should be imperative, especially in the mega projects to design strategic control and prevention methods.

Epidemic outbreak of anthroponotic cutaneous leishmaniasis in Kohat District, Khyber Pakhtunkhwa, Pakistan

An epidemiological and molecular study was carried out for the first time in Kohat District of Khyber Pakhtunkhwa (KP) province, Pakistan from April 2015 to May 2016 to determine the prevalence of Cutaneous Leishmaniasis (CL) in local population and Internally Displaced People (IDPs). In 13 different villages, a total of 1359 (out of 26,250 individuals belonging to local population) and 140 (out of 3615 IDPs residing in these villages) cases were recorded and 300 samples were collected. The total prevalence of CL in local population was 5.17% with active lesions and scar prevalence of 3.91% and 1.26% respectively. Similarly a prevalence of 3.86% for CL was recorded in IDPs. Highest number of IDPs having CL active lesions and scars were recorded in villages Sherkot, Surgul, and Jarma and their presence was positively correlated with CL in local population. Age wise prevalence was highest in young children of age group 1-15 years. The microscopic examination showed 64.33% (193/300) positive samples while kinteoplastic PCR showed 84.66% (254/300) positive. For the first time in KP province, 2/784 sandflies trapped from the study villages was found positive for Leishmania by PCR. Restriction Fragment Length Polymorphism of patients and sandflies samples revealed L. tropica as the prevalent Leishmania species in this district. The results of sequencing and RFLP identified L. tropica in Phlebotomus sergenti. This is the first ever report of molecular identification of L. tropica from sandflies of genus P. sergenti in Khyber Pakhtunkhwa province. This data can be helpful for health authorities in finding out new CL foci and to plan effective strategies for the provision of health facilities to poor people of this area.

Community-based surveillance of zoonotic parasites in a 'One Health' world: A systematic review

The One Health (OH) concept provides an integrated framework for observing and improving health issues involving human, animal, and environmental factors, and has been applied in particular to zoonotic disease problems. We conducted a systematic review of English and Chinese language peer-reviewed and grey literature databases to identify zoonotic endoparasite research utilizing an OH approach in community-based settings. Our review identified 32 articles where specimens collected simultaneously from all three OH domains (people, animals, and the environment) were assessed for endoparasite infection or exposure. Study sites spanned 23 countries, and research teams brought together an average of seven authors from two countries. Surveillance of blood-borne and gastrointestinal protozoa were most frequently reported (19 of 32; 59%), followed by trematodes, nematodes, and cestodes. Laboratory techniques varied greatly between studies, and only 16 identified parasites using Polymerase Chain Reaction (PCR) in all three OH domains. Our review identified important gaps in parasitology research operating under an OH framework. We recommend that investigators working in the realm of zoonotic disease strive to evaluate all three OH domains by integrating modern molecular tools as well as techniques provided by economists and social scientists.

Natural infection of bats with Leishmania in Ethiopia

The leishmaniases, a group of diseases with a worldwide-distribution, are caused by different species of Leishmania parasites. Both cutaneous and visceral leishmaniasis remain important public health problems in Ethiopia. Epidemiological cycles of these protozoans involve various sand fly (Diptera: Psychodidae) vectors and mammalian hosts, including humans. In recent years, Leishmania infections in bats have been reported in the New World countries endemic to leishmaniasis. The aim of this study was to survey natural Leishmania infection in bats collected from various regions of Ethiopia. Total DNA was isolated from spleens of 163 bats belonging to 23 species and 18 genera. Leishmania infection was detected by real-time (RT) PCR targeting a kinetoplast (k) DNA and internal transcribed spacer one (ITS1) gene of the parasite. Detection was confirmed by sequencing of the PCR products. Leishmania kDNA was detected in eight (4.9%) bats; four of them had been captured in the Aba-Roba and Awash-Methara regions that are endemic for leishmaniasis, while the other four specimens originated from non-endemic localities of Metu, Bedele and Masha. Leishmania isolates from two bats were confirmed by ITS1 PCR to be Leishmania tropica and Leishmania major, isolated from two individual bats, Cardioderma cor and Nycteris hispida, respectively. These results represent the first confirmed observation of natural infection of bats with the Old World Leishmania. Hence, bats should be considered putative hosts of Leishmania spp. affecting humans with a significant role in the transmission.

Epidemiological study of cutaneous leishmaniasis in Saesie Tsaeda-emba district, eastern Tigray, northern Ethiopia

Background

Cutaneous leishmaniasis (CL) is one of the endemic and neglected diseases known to exist in Ethiopian highlands. However, little is known about its epidemiological characteristics. Hence, this study was initiated and conducted from November 2011 to April 2012 to assess the epidemiological situation of CL in Saesie Tsaeda-emba District.

Methods

A cross sectional design was employed in six randomly selected Peasant associations and a house to house survey was carried out in the District. Detailed clinical assessment, and smear and culture for Leishmania parasite detection were done to confirm clinical suspension. Polymerase Chain Reaction and Restriction Fragment Length Polymorphism (PCR-RFLP) analysis of the ribosomal DNA Internal Transcribed Spacer (ITS-1) sequences was used to type isolates. Sandfly collection was also conducted in possible micro-habitats of the target areas.

Results

The overall prevalence of CL in the District was 14.0% (6.7% for active lesion and 7.3% for scar) with the highest prevalence amongst the age group of 10–19 years. Field isolates typed were L. aethiopica. Environmental and host risk factors significantly associated with CL distribution were age, study Peasant associations, presence of cave/gorge, walls with cracks and/or holes, presence of hyrax, animal burrow, animal dung and farm land near to residents’ houses. Five phlebotomine sandflies, Phlebotomus longipes, Sergentomyia bedfordi, S.africana, S.schwetzi and S.antenata were captured.

Conclusion

All the precipitating factors in the area are indicative of the public health importance of CL although there has been little attention given. The present study is a starter for wider investigation into the mode of its transmission, incrimination of sandfly vectors and possible animal reservoirs. Detailed information will be the basis to launch effective control of CL in the area.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-0758-9) contains supplementary material, which is available to authorized users.

Multilocus microsatellite signature and identification of specific molecular markers for Leishmania aethiopica

BACKGROUND

Leishmaniasis is a clinically and epidemiologically diverse zoonotic disease caused by obligatory, intracellular protozoan parasites of the genus Leishmania. Cutaneous leishmaniasis is the most widely distributed form of the disease characterized by skin lesions. Leishmania aethiopica is considered the predominant etiological agent in Ethiopia. The current study was aimed at developing multilocus microsatellite markers for L. aethiopica isolated from human cutaneous leishmaniasis patients in Ethiopia.

RESULTS

L. aethiopica parasites for the study were obtained from Ethiopia and laboratory analysis was conducted at The Ohio State University. DNA was extracted from cultured parasites and an internal transcribed spacer located at the ribosomal region of L. aethiopica genomic DNA was PCR amplified for species identification. Microsatellite markers were identified using multilocus microsatellite typing. We generated an enriched genomic library, and using Primer3 software, designed PCR primers to amplify sequences flanking the detected microsatellites. Subsequent screening of the amplified markers for length variations was performed by gel electrophoresis.Using a variety of molecular methods, 22 different microsatellite markers were identified and tested for typing L. aethiopica strains using a number of clinical isolates. Of the 22 markers tested, 5 were polymorphic and showed distinctive multilocus genotypes, classifying them into four clusters. One marker was found to be specific for L. aethiopica, discriminating it from other species of Leishmania.

CONCLUSION

Multilocus microsatellite typing using the markers developed in this study could be useful for epidemiological and population genetic studies of strains of L. aethiopica in order to investigate the structure and dynamics of the corresponding natural foci. It could also help to answer specific clinical questions, such as the occurrence of local and diffuse lesions, strain correlates of parasite persistence after subclinical infection and lesion comparisons from patients suffering from L. aethiopica infections.

Bibliometric analysis of leishmaniasis research in Medline (1945-2010)

Background

Publications are often used as a measure of success of research work. Leishmaniasis is considered endemic in 98 countries, most of which are developing. This article describes a bibliometric review of the literature on leishmaniasis research indexed in PubMed during a 66-year period.

Methods

Medline was used via the PubMed online service of the US National Library of Medicine. The search strategy was Leishmania [MeSH] or leishmaniasis [MeSH] from 1 January 1945 until 31 December 2010. Neither language nor document type restrictions were employed.

Results

A total of 20,780 references were retrieved. The number of publications increased steadily over time, with 3,380 publications from 1945-1980 to 8,267 from 2001-2010. Leishmaniasis documents were published in 1,846 scientific journals, and Transactions of the Royal Society of Tropical Medicine and Hygiene (4.9%) was the top one. The USA was the predominant country by considering the first author’s institutional address (16.8%), followed by Brazil (14.9%), and then India (9.0%), however Brazil leads the scientific output in 2001-2010 period (18.5%), followed by the USA (13.5%) and India (10%). The production ranking changed when the number of publications was normalised by population (Israel and Switzerland), by gross domestic product (Nepal and Tunisia), and by gross national income per capita (India and Ethiopia). For geographical area, Europe led (31.7%), followed by Latin America (24.5%).

Conclusions

We have found an increase in the number of publications in the field of leishmaniasis. The USA and Brazil led scientific production on leishmaniasis research.

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.

Local increase of arginase activity in lesions of patients with cutaneous leishmaniasis in Ethiopia

Background

Cutaneous leishmaniasis is a vector-borne disease that is in Ethiopia mainly caused by the parasite Leishmania aethiopica. This neglected tropical disease is common in rural areas and causes serious morbidity. Persistent nonhealing cutaneous leishmaniasis has been associated with poor T cell mediated responses; however, the underlying mechanisms are not well understood.

Methodology/Principal Findings

We have recently shown in an experimental model of cutaneous leishmaniasis that arginase-induced L-arginine metabolism suppresses antigen-specific T cell responses at the site of pathology, but not in the periphery. To test whether these results translate to human disease, we recruited patients presenting with localized lesions of cutaneous leishmaniasis and assessed the levels of arginase activity in cells isolated from peripheral blood and from skin biopsies. Arginase activity was similar in peripheral blood mononuclear cells (PBMCs) from patients and healthy controls. In sharp contrast, arginase activity was significantly increased in lesion biopsies of patients with localized cutaneous leishmaniasis as compared with controls. Furthermore, we found that the expression levels of CD3ζ, CD4 and CD8 molecules were considerably lower at the site of pathology as compared to those observed in paired PBMCs.

Conclusion

Our results suggest that increased arginase in lesions of patients with cutaneous leishmaniasis might play a role in the pathogenesis of the disease by impairing T cell effector functions.

The leishmaniases are a complex of diseases caused by Leishmania parasites. Currently, the diseases affect an estimated 12 million people in 88 countries, and approximately 350 million more people are at risk. The leishmaniases belong to the most neglected tropical diseases, affecting the poorest populations, for whom access to diagnosis and effective treatment are often not available. Leishmania parasites infect cells of the immune system called macrophages, which have the capacity to eliminate the intracellular parasites when they receive the appropriate signals from other cells of the immune system. In nonhealing persistent leishmaniasis, lymphocytes are unable to transmit the signals to macrophages required to kill the intracellular parasites. The local upregulation of the enzyme arginase has been shown to impair lymphocyte effector functions at the site of pathology. In this study, we tested the activity of this enzyme in skin lesions of patients presenting with localized cutaneous leishmaniasis. Our results show that arginase is highly upregulated in these lesions. This increase in arginase activity coincides with lower expression of a signalling molecule in lymphocytes, which is essential for efficient activation of these cells. These results suggest that increased arginase expression in the localized cutaneous lesions might contribute to persistent disease in patients presenting with cutaneous leishmaniasis.