Twice neglected? Neglected diseases in neglected populations

The global burden of neglected zoonotic diseases: Current state of evidence

The majority of emerging infectious diseases are zoonoses, most of which are classified as "neglected". By affecting both humans and animals, zoonoses pose a dual burden. The disability-adjusted life year (DALY) metric quantifies human health burden since it combines mortality and morbidity. This review aims to describe and analyze the current state of evidence on neglected zoonotic diseases (NZDs) burden and start a discussion on the current understanding of the global burden of NZDs. We identified 26 priority NZDs through consulting three international repositories for national prioritization exercises. A systematic review of global and national burden of disease (BoD) studies was conducted using pre-selected databases. Data on diseases, location and DALYs were extracted for each eligible study. A total of 1887 records were screened, resulting in 74 eligible studies. The highest number of BoD was found for non-typhoidal salmonellosis (23), whereas no estimates were found for West Nile, Marburg and Lassa fever. Geographically, the highest number of studies was performed in the Netherlands (11), China (5) and Iran (4). The number of BoD retrieved mismatched the perceived importance in national prioritization exercises. For example, anthrax was considered a priority NZD in 65 countries; however, only one national study estimating BoD was retrieved. By summing the available global estimates, the selected NZDs caused at least 21 million DALYs per year, a similar order of magnitude to (but less than) the burden due to foodborne disease (included in the Foodborne Disease Burden Epidemiology Reference Group). The global burden of disease landscape of NZDs remains scattered. There are several priority NZDs for which no burden estimates exist, and the number of BoD studies does not reflect national disease priorities. To have complete and consistent estimates of the global burden of NZDs, these diseases should be integrated in larger global burden of disease initiatives.

Investigation of the Potential Targets behind the Promising and Highly Selective Antileishmanial Action of Synthetic Flavonoid Derivatives

Leishmaniases are among the neglected tropical diseases that still cause devastating health, social, and economic consequences to more than 350 million people worldwide. Despite efforts to combat these vector-borne diseases, their incidence does not decrease. Meanwhile, current antileishmanial drugs are old and highly toxic, and safer presentations are unaffordable to the most severely affected human populations. In a previous study by our research group, we synthesized 17 flavonoid derivatives that demonstrated impressive inhibition capacity against rCPB2.8, rCPB3, and rH84Y. These cysteine proteases are highly expressed in the amastigote stage, the target form of the parasite. However, although these compounds have been already described in the literature, until now, the amastigote effect of any of these molecules has not been proven. In this work, we aimed to deeply analyze the antileishmanial action of this set of synthetic flavonoid derivatives by correlating their ability to inhibit cysteine proteases with the action against the parasite. Among all the synthesized flavonoid derivatives, 11 of them showed high activity against amastigotes of Leishmania amazonensis, also providing safety to mammalian host cells. Furthermore, the high production of nitric oxide by infected cells treated with the most active cysteine protease B (CPB) inhibitors confirms a potential immunomodulatory response of macrophages. Besides, considering flavonoids as multitarget drugs, we also investigated other potential antileishmanial mechanisms. The most active compounds were selected to investigate another potential biological pathway behind their antileishmanial action using flow cytometry analysis. The results confirmed an oxidative stress after 48 h of treatment. These data represent an important step toward the validation of CPB as an antileishmanial target, as well as aiding in new drug discovery studies based on this protease.

Antileishmanial activity of 2-amino-thiophene derivative SB-200

Leishmaniasis, presenting the highest number of cases worldwide is one of the most serious Neglected Tropical Diseases (NTDs). Clinical manifestations are intrinsically related to the host's immune response making immunomodulatory substances the target of numerous studies on antileishmanial activity. The currently available drugs used for treatment present various problems including high toxicity, low efficacy, and associated drug resistance. The search for therapeutic alternatives is urgent, and in this context, thiophene derivatives appear to be a promising therapeutic alternative (many have shown promising anti-leishmanial activity). The objective of this study was to investigate the antileishmanial activity of the 2-amino-thiophenic derivative SB-200. The thiophenic derivative was effective in inhibiting the growth of Leishmania braziliensis, Leishmania major, and Leishmania infantum promastigotes, obtaining respective IC50 values of 4.25 μM, 4.65 μM, and 3.96 μM. For L. infantum, it was demonstrated that the antipromastigote effect of SB-200 is associated with cell membrane integrity losses, and with morphological changes observed during scanning and transmission electron microscopy. Cytotoxicity was performed for J774.A1 macrophages and VERO cells, to obtain a CC50 of 42.52 μM and a SI of 10.74 for macrophages and a CC50 of 39.2 μM and an SI of 9.89 for VERO cells. The anti-amastigote activity of SB-200 revealed an IC50 of 2.85 μM and an SI of 14.97 against macrophages and SI of 13.8 for VERO cells. The anti-amastigote activity of SB-200 is associated with in vitro immunomodulation. For acute toxicity, SB-200 against Zophobas morio larvae permitted 100% survival. We conclude that the 2-amino-thiophenic derivative SB-200 is a promising candidate for in vivo anti-leishmania drug tests to evaluate its activity, efficacy, and safety.