Viscerální leishmanióza v Etiopii: přenos a variabilita

Leishmaniasis, a protozoan infection caused by Leishmania parasites is a neglected disease affecting millions across the world. It is exhibited by diverse clinical presentations that broadly classified as visceral (VL) and cutaneous (CL) leishmaniasis. Both CL and VL are endemic to Ethiopia, which the later is generally considered as fatal, if left untreated. Leishmania donovani is the sole agent of Ethiopian human VL. In Africa, the worst VL affected regions are found in Sudan and Ethiopia. VL is considered as an endemic and at the same time emerging disease in north, northwest, south and southwest with sporadic cases in Eastern Ethiopia. The epidemiology is more or less associated with seasonal migration to endemic areas and HIV/AIDS. The transmission of CL in Ethiopia is known to involve zoonotic cycle while VL transmission isn't clearly understood despite traditional generalization of anthroponosis in East African platform. The aim of this dissertation is to determine VL transmission cycle and study variability L. donovani and P. orientalis in Ethiopia. Studies on human and non-human hosts were conducted to determine the transmission dynamics. To assess the role of symptomatic and asymptomatic L. donovani infected persons in the epidemiology of VL, a community based cohort was conducted. As the...Leishmanióza, opomíjené infekční onemocnění působené parazitickými prvoky rodu Leishmania, postihuje miliony lidí po celém světě. Onemocnění má různé klinické projevy, z nichž nejčastější dva jsou viscerální (VL) a kožní (CL) forma leishmaniózy, a obě tyto formy jsou v Etiopii endemické. Leishmania donovani je výhradním původcem lidské VL v Etiopii a pokud se neléčí, je považována za smrtelnou. V Africe jsou nejhůře postižené regiony v Súdánu a Etiopii, kde je VL považována za endemické a zároveň nově se objevující onemocnění na severu, severozápadě, jihu a jihozápadě země, rovněž tak jsou známy sporadické případy ve východní Etiopii. Epidemiologii onemocnění je více či méně spojené se sezónní migrací dělníků do endemických oblastí a rovněž s výskytem HIV/AIDS. Přenos kožní leishmaniózy je v Etiopii svázán se zoonotickým cyklem, zatímco přenos VL není dosud zcela objasněn a je v celé východoafrické oblasti spíše chápán v tradičním pojetí jako antroponóza. Cílem předložené disertační práce bylo zjistit jaký je cyklus přenosu viscerální leishmaniózy v Etiopii, druhým cílem pak bylo sledovat variabilitu parazitů a jejich přenašečů. Abychom mohli stanovit dynamiku a způsob přenosu leishmanií, byly prováděny studie zaměřené na lidské i zvířecí hostitele. Kohortová studie zaměřená na místní komunitu lidí...Department of ParasitologyKatedra parazitologieFaculty of SciencePřírodovědecká fakult

Visceral leishmaniasis in Ethiopia: transmission and variability

Leishmaniasis, a protozoan infection caused by Leishmania parasites is a neglected disease affecting millions across the world. It is exhibited by diverse clinical presentations that broadly classified as visceral (VL) and cutaneous (CL) leishmaniasis. Both CL and VL are endemic to Ethiopia, which the later is generally considered as fatal, if left untreated. Leishmania donovani is the sole agent of Ethiopian human VL. In Africa, the worst VL affected regions are found in Sudan and Ethiopia. VL is considered as an endemic and at the same time emerging disease in north, northwest, south and southwest with sporadic cases in Eastern Ethiopia. The epidemiology is more or less associated with seasonal migration to endemic areas and HIV/AIDS. The transmission of CL in Ethiopia is known to involve zoonotic cycle while VL transmission isn't clearly understood despite traditional generalization of anthroponosis in East African platform. The aim of this dissertation is to determine VL transmission cycle and study variability L. donovani and P. orientalis in Ethiopia. Studies on human and non-human hosts were conducted to determine the transmission dynamics. To assess the role of symptomatic and asymptomatic L. donovani infected persons in the epidemiology of VL, a community based cohort was conducted. As the..

Inference of population structure of Leishmania donovani strains isolated from different Ethiopian visceral leishmaniasis endemic areas.

BACKGROUND: Parasites' evolution in response to parasite-targeted control strategies, such as vaccines and drugs, is known to be influenced by their population genetic structure. The aim of this study was to describe the population structure of Ethiopian strains of Leishmania donovani derived from different areas endemic for visceral leishmaniasis (VL) as a prerequisite for the design of effective control strategies against the disease. METHODOLOGY/PRINCIPAL FINDINGS: Sixty-three strains of L. donovani newly isolated from VL cases in the two main Ethiopian foci, in the north Ethiopia (NE) and south Ethiopia (SE) of the country were investigated by using 14 highly polymorphic microsatellite markers. The microsatellite profiles of 60 previously analysed L. donovani strains from Sudan, Kenya and India were included for comparison. Multilocus microsatellite typing placed strains from SE and Kenya (n = 30) in one population and strains from NE and Sudan (n = 65) in another. These two East African populations corresponded to the areas of distribution of two different sand fly vectors. In NE and Sudan Phlebotomus orientalis has been implicated to transmit the parasites and in SE and Kenya P. martini. The genetic differences between parasites from NE and SE are also congruent with some phenotypic differences. Each of these populations was further divided into two subpopulations. Interestingly, in one of the subpopulations of the population NE we observed predominance of strains isolated from HIV-VL co-infected patients and of strains with putative hybrid genotypes. Furthermore, high inbreeding irreconcilable from strict clonal reproduction was found for strains from SE and Kenya indicating a mixed-mating system. CONCLUSIONS/SIGNIFICANCE: This study identified a hierarchical population structure of L. donovani in East Africa. The existence of two main, genetically and geographically separated, populations could reflect different parasite-vector associations, different ecologies and varying host backgrounds and should be further investigated

Blood parasites (Trypanosoma, Leucocytozoon, Haemoproteus) in the Eurasian sparrowhawk (Accipiter nisus): diversity, incidence and persistence of infection at the individual level

Abstract Background A high prevalence of parasites may result from life-long persistence of infection or from high reinfection rates. We have studied blood parasites in a breeding population of the accipitrid raptor, Eurasian sparrowhawk (Accipiter nisus), to determine parasite diversity and turnover. Methods During this 7-year study, 210 adult Eurasian sparrowhawks breeding in the city of Prague were checked for parasites using several diagnostic methods. Results In both female and male raptors, parasites of the genus Leucocytozoon were the most prevalent (92% and 85%, respectively) followed in decreasing order of prevalence by those of genus Trypanosoma (74% and 68%, respectively) and genus Haemoproteus (46% and 16%, respectively). The prevalence of all parasites increased with age in both sexes, with the females at each respective age having the higher prevalence. There was a positive association between Haemoproteus and Leucocytozoon infections. Persistence at the individual level was higher than incidence for Trypanosoma and Haemoproteus. In the case of Leucocytozoon and Trypanosoma, most individuals probably become infected in their first year of life or even before dispersal from the nest. The detected parasites belonged to Trypanosoma avium sensu stricto, Leucocytozoon sp. (haplotypes ACNI1 and ACNI3) and Leucocytozoon mathisi (haplotype ACNI4) and two new lineages of the Haemoproteus elani complex (ACCNIS6 and ACCNIS7). Detailed analysis of parasite lineages in individuals that were repeatedly sampled revealed lineage turnover that would otherwise remain hidden. Phylogenetic analysis revealed that the detected Haemoproteus belongs to a phylogenetically distant group whose taxonomic position requires further analysis. Conclusions All three genera of blood parasites persist in infected individuals, thus enabling sustainability of vector transmission cycles. Prevalence increases with age; however, there is a high turnover of Leucocytozoon lineages. No clear evidence of parasite-induced mortality was found, and most of the individuals were infected early in life, particularly in the case of Leucocytozoon. Graphical abstrac

Effect of nutrition on the life cycle of two <i>P. orientalis</i> colonies.

<p>Data originate from the offspring of about 4,600 ovipositing females (2,200 MW and 2,400 AZ) during a 3 month period. <b>1A</b>: On the non-autoclaved food the number of adults emerging from pupae peaked on week 8 PBM in MW, and week 9 PBM in AZ. All individuals completed the life cycle within 13 and 20 weeks for MW and AZ, respectively. <b>1B</b>: On the autoclaved food the life cycle was prolonged and the larval growth appeared less synchronized in both colonies. The impact was more significant in the AZ colony: emergence of AZ adults peaked on week 13 (four weeks later than on non-autoclaved food).</p

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

WOS:000357470300003 PMID: 26152578Background: 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.publishersversionpublishe

Effect of initial infective dose on development of <i>L. donovani</i> (GR 374) in <i>P. orientalis</i>.

<p><b>4A</b>: Infected females of <i>P. orientalis</i> (MW colony) were examined microscopically 2–3, 6 and 10 days post-bloodmeal (PBM). The infection intensity was classified as described in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002187#pntd-0002187-g003" target="_blank">Fig. 3</a>. <b>4B</b>: Parasite numbers were determined using Q-PCR at 10 days PBM. Twenty females were used per group.</p

Development of <i>L. donovani</i> (GR 374) in females of two <i>P. orientalis</i> colonies.

<p>Sand flies were infected by feeding on a suspension of 10⁵ promastigotes/ml of blood and kept at 26°C. <b>3A</b>: Infected females of <i>P. orientalis</i> were examined microscopically 2, 5–6 and 8–11 days post-bloodmeal (PBM). The infection intensities were classified into three categories according to their intensity: heavy (more than 1,000 parasites per gut [black]), moderate (100–1,000 parasites [grey]) and light (1–100 parasites [white]). Numbers above the bars indicate the number of dissected females. <b>3B</b>: Parasite numbers from 40–50 individual females were quantified by Q-PCR targeted on amplification of <i>Leishmania</i> kDNA 10 days PBM.</p

Polymorphism in the HASPB Repeat Region of East African <em>Leishmania donovani</em> Strains

<div><h3>Background/Objectives</h3><p>Visceral leishmaniasis (VL) caused by <em>Leishmania donovani</em> is a major health problem in Ethiopia. Parasites in disparate regions are transmitted by different vectors, and cluster in distinctive genotypes. Recently isolated strains from VL and HIV-VL co-infected patients in north and south Ethiopia were characterized as part of a longitudinal study on VL transmission.</p> <h3>Methodology/Principal Findings</h3><p>Sixty-three <em>L. donovani</em> strains were examined by polymerase chain reaction (PCR) targeting three regions: internal transcribed spacer 1 (ITS1), cysteine protease B (cpb), and HASPB (k26). ITS1- and cpb - PCR identified these strains as <em>L. donovani</em>. Interestingly, the k26 - PCR amplicon size varied depending on the patient's geographic origin. Most strains from northwestern Ethiopia (36/40) produced a 290 bp product with a minority (4/40) giving a 410 bp amplicon. All of the latter strains were isolated from patients with HIV-VL co-infections, while the former group contained both VL and HIV-VL co-infected patients. Almost all the strains (20/23) from southwestern Ethiopia produced a 450 bp amplicon with smaller products (290 or 360 bp) only observed for three strains. Sudanese strains produced amplicons identical (290 bp) to those found in northwestern Ethiopia; while Kenyan strains gave larger PCR products (500 and 650 bp). High-resolution melt (HRM) analysis distinguished the different PCR products. Sequence analysis showed that the k26 repeat region in <em>L. donovani</em> is comprised of polymorphic 13 and 14 amino acid motifs. The 13 amino acid peptide motifs, prevalent in <em>L. donovani</em>, are rare in <em>L. infantum</em>. The number and order of the repeats in <em>L. donovani</em> varies between geographic regions.</p> <h3>Conclusions/Significance</h3><p>HASPB repeat region (k26) shows considerable polymorphism among <em>L. donovani</em> strains from different regions in East Africa. This should be taken into account when designing diagnostic assays and vaccines based on this antigen.</p> </div