Seroepidemiology and molecular diversity of Leishmania donovani complex in Georgia

Background Leishmaniasis includes multiple clinical syndromes, most notably visceral, cutaneous, and mucosal forms. Visceral leishmaniasis (VL), also known as kala-azar, is a potentially fatal disease endemic to large parts of Africa and Asia, and in South-Eastern Europe (Greece, Turkey, Georgia). Visceral leishmaniasis is a parasitic zoonosis caused by species of the L. donovani complex. In the classical epidemiological model the main reservoir for VL are canines. Methods The study included a cohort of 513 individuals of both genders (190 males and 323 females) from the ages of 1 to 70 years that were screened in ten villages across two districts in Kakheti using the Kalazar Detect™ rK39 rapid diagnostic test. The phylogenetic diversity patterns of local strains, based on the rDNA internal transcribed spacer (ITS) sequences, were assessed for samples obtained from patients with suspected L. donovani infection, from canine reservoirs and from Phlebotomus sand flies obtained from different geographical areas of Georgia and from Azerbaijan. Results Out of a total of 600 domestic dog blood samples 95 (15.8 %) were positive by rK39 rapid diagnostic tests. For symptomatic domestic dogs, the testing of conjunctival swabs or bone marrow aspirates revealed a higher VL incidence in Kvareli District (Kvareli; 19.4 %, n = 329) compared with that observed for Sagarejo District (Sagarejo; 11.4 %, n = 271). A total of 231 sand flies of both genders were collected during the 2-month period; of the 114 females, 1.75 % were PCR positive for the presence of Leishmania spp. Conclusions VL infection rates remain high in both canines and humans in Georgia, with disease in several known natural foci. The genetic relationships derived from rDNA internal transcribed spacer (ITS) sequence comparisons identified genetic subgroups, revealing preliminary insights into the genetic structure of L. donovani complex members currently circulating in the South Caucasus and demonstrates the utility of ITS-based genotyping in the resource-limited country of Georgia

The impact of industrial activities on vector-borne disease transmission.

Industrial activities have produced profound changes in the natural environment, including the mass removal of trees, fragmentation of habitats, and creation of larval mosquito breeding sites, that have allowed the vectors of disease pathogens to thrive. We conducted a review of the literature to assess the impact of industrial activities on vector-borne disease transmission. Our study shows that industrial activities may be coupled with significant changes to human demographics that can potentially increase contact between pathogens, vectors and hosts, and produce a shift of parasites and susceptible populations between low and high disease endemic areas. Indeed, where vector-borne diseases and industrial activities intersect, large numbers of potentially immunologically naïve people may be exposed to infection and lack the knowledge and means to protect themselves from infection. Such areas are typically associated with inadequate access to quality health care, thus allowing industrial development and production sites to become important foci of transmission. The altered local vector ecologies, and the changes in disease dynamics that changes affect, create challenges for under-resourced health care and vector-control systems

A systematic review (1990–2021) of wild animals infected with zoonotic leishmania

Leishmaniasis are neglected diseases caused by several species of Leishmania that affect humans and many domestic and wild animals with a worldwide distribution. The objectives of this review are to identify wild animals naturally infected with zoonotic Leishmania species as well as the organs infected, methods employed for detection and percentage of infection. A literature search starting from 1990 was performed following the PRISMA methodology and 161 reports were included. One hundred and eighty‐nine species from ten orders (i.e., Carnivora, Chiroptera, Cingulata, Didelphimorphia, Diprotodontia, Lagomorpha, Eulipotyphla, Pilosa, Primates and Rodentia) were reported to be infected, and a few animals were classified only at the genus level. An exhaustive list of species; diagnostic techniques, including PCR targets; infected organs; number of animals explored and percentage of positives are presented. L. infantum infection was described in 98 wild species and L. (Viania) spp. in 52 wild animals, while L. mexicana, L. amazonensis, L. major and L. tropica were described in fewer than 32 animals each. During the last decade, intense research revealed new hosts within Chiroptera and Lagomorpha. Carnivores and rodents were the most relevant hosts for L. infantum and L. (Viannia) spp., with some species showing lesions, although in most of the studies clinical signs were not reported

Anticipatory Action for climate-sensitive infectious diseases: East Africa Regional Assessment

Anticipatory Action, a crucial component of the disaster risk management cycle, formalizes the connection between early warning and early action based on forecasted hazards. It is an approach that operates on various scales, shaped by organizational mandates, local contexts, specific hazards and available forecasts. Key parameters include a focus on mitigating forecastable hazard impacts, designing actions based on predictive analyses, and implementing interventions before the hazard's impact or its most acute effects are felt. In recent years, growing attention has been given to developing Anticipatory Action for epidemics.This report attempts to provide a guide on evaluating the different factors to assess and implement Anticipatory Action for climate-sensitive infectious diseases in East Africa, particularly Ethiopia (Annex A) and Kenya (Annex B).We focus on climate change in the region, identify priority climate-sensitive infectious diseases, and investigate potential mechanisms on how climate and non-climate drivers can affect climate-sensitive infectious disease transmission and outbreaks. Furthermore, we analyse existing preparedness and prevention activities in the region, determine the feasibility of Anticipatory Action to support epidemic preparedness and prevention, and give recommendations for potential Anticipatory Action for priority climate-sensitive infectious diseases in East Africa, Ethiopia and Kenya

Informing new or improved vector control tools for reducing the malaria burden in Tanzania: a qualitative exploration of perceptions of mosquitoes and methods for their control among the residents of Dar es Salaam.

Background The effectiveness of malaria prevention with long-lasting insecticidal nets and indoor residual spraying is limited by emerging insecticide resistance, evasive mosquito behaviours that include outdoor biting, sub-optimal implementation and inappropriate use. New vector control interventions are required and their potential effectiveness will be enhanced if existing household perceptions and practices are integrated into intervention design. Methods This qualitative descriptive study used focus groups discussions, in-depth interviews and photovoice methods to explore mosquito control perceptions and practices among residents in four study sites in Dar es Salaam, Tanzania. Results Mosquitoes were perceived as a growing problem, directly attributed to widespread environmental deterioration and lack of effective mosquito control interventions. Malaria and nuisance biting were perceived as the main problem caused by mosquitoes. Breeding sites were clearly distinguished from resting sites but residents did not differentiate between habitats producing malaria vector mosquitoes and others producing mostly nuisance mosquitoes. The most frequently mentioned protection methods in the wealthiest locations were bed nets, aerosol insecticide sprays, window screens, and fumigation, while bed nets were most frequently mentioned and described as ‘part of the culture’ in the least wealthy locations. Mosquito-proofed housing was consistently viewed as desirable, but considered unaffordable outside wealthiest locations. Slapping and covering up with clothing were most commonly used to prevent biting outdoors. Despite their utility outdoors, topical repellents applied to the skin were considered expensive, and viewed with suspicion due to perceived side effects. Improving the local environment was the preferred method for preventing outdoor biting. Affordability, effectiveness, availability, practicality, as well as social influences, such as government recommendations, socialization and internalization (familiarization and habit) were described as key factors influencing uptake. Conclusion Outdoor transmission is widely accepted as an obstacle to malaria elimination. Larval source management, targeting both malaria vectors and nuisance-biting mosquitoes, is the preferred method for mosquito control among the residents of Dar es Salaam and should be prioritized for development alongside new methods for outdoor personal protection. Even if made available, effective and affordable, these additional interventions may require time and user experience to achieve positive reputations and trustworthiness

Computational and statistical approaches for quantifying the role of multi-scale heterogeneity in Leishmania transmission dynamics

Leishmaniasis, a neglected tropical disease caused by infection with Leishmania parasites, affects millions of people annually across the globe. Leishmania transmission is facilitated by the sand fly vector, thus occurring across a range of climates with notable hotspots in Brazil and India. Its persistence despite ongoing eradication efforts underscores the importance of a complete understanding of the transmission dynamics in a range of environments. Developing this understanding requires tailored tools as the transmission dynamics are affected by heterogeneity at multiple scales, giving rise to a complex web of interactions. At the micro-scale, transmission is influenced by the heterogeneous parasite distributions of the host’s skin as well as the complex parasite life cycle in the sand fly and its link to sand fly biting behaviour. We derive and parameterise a simple model incorporating these factors, finding that their interactions give rise to unexpected transmission opportunities. The communities in which leishmaniasis typically propagates are highly heterogeneous but also ideal candidates for deploying network models. We test analytic estimates for two epidemiologically relevant quantities, the R0 (the average number of secondary infections caused by a single infected individual over their entire duration of infection) and the endemic equilibrium, in the context of heterogeneous networks. Although both prove to be unreliable for these structured communities, they have the potential to improve our understanding of when and where epidemics are likely to occur and be more severe. We also demonstrate the potential of using survival analysis to investigate medium and large-scale dynamics, first by confirming the role of distance in leishmaniasis transmissibility at the community level, and then by highlighting the role of social vulnerability in creating endemic hotspots. We then offer guidance for optimal application of survival analysis to future leishmaniasis research. Finally, these findings are synthesised with the wider literature to identify potential methodological improvements and further avenues of inquiry to further develop our knowledge of leishmaniasis transmission