Co-endemic Regions Research Articles

Heterogeneous mosquito exposure increases Plasmodium vivax and Plasmodium falciparum co-infections: a modelling study.

In malaria-endemic regions, Plasmodium vivax and Plasmodium falciparum coexist and may interact. For instance, fevers induced by P. falciparum might activate dormant P. vivax parasites and concurrent radical cure of both species has been proposed to prevent relapses. Heterogeneous mosquito exposure may contribute to the dependence of both parasites. We conducted a literature review on their respective prevalence and that of co-infections. The data revealed a positive correlation between P. vivax and P. falciparum prevalence, and co-infection prevalences exceeding expectations assuming infections occur independently. We used the review data to fit a compartmental model of co-infections that features heterogenous mosquito exposure. The fit suggests that heterogeneous exposure sufficiently explains the observed departure from independence. Finally, we performed simulations under the model assessing the impact on P. vivax prevalence of the activation-by-fever hypothesis and the radical cure proposition. We demonstrated a moderate impact of allowing P. falciparum fevers to reactivate P. vivax and a substantial impact of treating P. falciparum cases with radical cure. Our model highlights dependence between P. falciparum and P. vivax and emphasizes the influence of heterogeneous mosquito exposure. This simple framework can inform the design of more complex models assessing integrated malaria control strategies in coendemic regions.

Co-infection of dengue and Zika viruses mutually enhances viral replication in the mosquito Aedes aegypti

BackgroundThe mosquito Aedes aegypti transmits two of the most serious mosquito-borne viruses, dengue virus (DENV) and Zika virus (ZIKV), which results in significant human morbidity and mortality worldwide. The quickly shifting landscapes of DENV and ZIKV endemicity worldwide raise concerns that their co-circulation through the Ae. aegypti mosquito vector could greatly exacerbate the disease burden in humans. Recent reports have indicated an increase in the number of co-infection cases in expanding co-endemic regions; however, the impact of co-infection on viral infection and the detailed molecular mechanisms remain to be defined.MethodsC6/36 (Aedes albopictus) cells were cultured in Dulbecco's modified Eagle medium/Mitsuhashi and Maramorosch Insect Medium (DMEM/MM) (1:1) containing 2% heat-inactivated fetal bovine serum and 1× penicillin/streptomycin solution. For virus propagation, the cells were infected with either DENV serotype 2 (DENV2) strain 16681 or ZIKV isolate Thailand/1610acTw (MF692778.1). Mosquitoes (Ae. aegypti UGAL [University of Georgia Laboratory]/Rockefeller strain) were orally infected with DENV2 and ZIKV through infectious blood-feeding.ResultsWe first examined viral replication activity in cells infected simultaneously, or sequentially, with DENV and ZIKV, and found interspecies binding of viral genomic transcripts to the non-structural protein 5 (NS5). When we challenged Ae. aegypti mosquitos with both DENV2 and ZIKV sequentially to probe similar interactions, virus production and vector susceptibility to infection were significantly enhanced.ConclusionsOur results suggest that DENV2 and ZIKV simultaneously establishing infection in the Ae. aegypti mosquito vector may augment one another during replication. The data also implicate the homologous NS5 protein as a key intersection between the flaviviruses in co-infection, highlighting it as a potential target for vector control.

Mathematical Analysis of Sensitive Parameters on the Dynamical Transmission of HIV-Malaria Co-infection

Malaria disease increases the mortality rate of HIV patients. In this work, a mathematical model incorporating an infected, undetected, and treated set of people was developed. The analysis showed that the model is well-posed, the disease-free equilibrium for the model was obtained, and the basic reproduction number of the HIV-malaria co-infection model was calculated. The 14 compartmental models were analyzed for stability, and it was established that the disease-free equilibrium of each model and their co-infections were locally and globally asymptotically stable whenever the basic reproduction number was less than unity or endemic otherwise. Based on the sensitivity analysis, the parameter that has the greatest impact is the contact rate; therefore, it is recommended for public health policies aimed at reducing the burden of these diseases in co-endemic regions.

Linkages between malaria and malnutrition in co-endemic regions of India

IntroductionMalaria and malnutrition are key public health challenges in India. However, the relationship between them is poorly understood. Here, we aimed to elucidate the potential interactions between the two health...

The Human Filaria Loa loa: Update on Diagnostics and Immune Response.

Loa loa loiasis was considered an anecdotal disease 30 years ago. Its spread in Equatorial Africa and the side effects associated with mass drug administration programs against filariasis in co-endemic areas have drawn the attention of the international research community. Progress in research conducted to date has provided insight into the immunobiology of this parasite. An interesting finding reported in several studies is that 70% of individuals with loiasis do not carry microfilariae in their blood, and 30% are microfilaremic, suggesting the involvement of several immunological mechanisms, as shown by elevated specific IgG4 and IgE levels signifying a potential cross-linking mechanism between the two isotypes via L. loa antigen to prevent allergy. A mechanism of anergy in the appearance of microfilariae in the peripheral blood results in immunological unresponsiveness in individuals with microfilariae. There is an interaction between other pathogens (parasites, bacteria, viruses) in individuals co-infected with L. loa. The strong antigen cross-reactivity between L. loa and lymphatic filarial worms warrants a re-evaluation of the distribution of the latter in co-endemic regions. The mechanism of concomitant immunity observed in the elimination of microfilariae or infective larvae (third-stage larvae, L3) may be used for the conception of an immunoprophylactic strategy.

Modeling Co-infection of Bovine Brucellosis and Tuberculosis

Bovine tuberculosis and bovine brucellosis continue to cause serious economic and public health burden in low-income countries, especially in many regions of sub-Saharan Africa where the diseases are co-endemic. The economic burden of the two infections in low-income countries trigger important questions about the optimal intervention strategies in co-endemic regions. Hence, the need for comprehensive modelling studies to address such questions is therefore essential, yet only a limited of such studies exist to date despite the power of models to predict the future and, most importantly, to quantify the uncertainty in these predictions. Here, we develop a brucellosistuberculosis co-infection modelling framework that incorporates all relevant biological factors and culling of infectious animals-as the sole intervention strategy. We performed an optimal control study to assess the impact of culling infectious animals on controlling the prevalence of the two infections. Two objective functions have been considered, a linear and a quadratic. Existence and the characterization of the optimal control has been determined. Numerical results are carried out to illustrate the main findings. Our findings highlight the importance of optimal culling on controlling the spread of two infections.

Helminth-mediated disease tolerance in TB: A role for microbiota?

Intestinal helminth infections are most prevalent in peri-equatorial regions of the world and have an overlapping geographical distribution with Mycobacterium tuberculosis (Mtb) infection—the causative agent of tuberculosis (TB). Importantly, approximately 40% of TB patients are asymptomatically infected with helminth parasites. While experimental and epidemiological evidence suggest that helminth infections alter the course of TB, other studies do not support this link [1]. Although the direct immunomodulatory effects of helminth infections on adaptive host immunity have been studied extensively, these can only partially explain the complex nature of helminth–TB interactions. Indeed, the potent immunomodulatory abilities of helminths may even reduce TB-associated tissue pathology [1] and contribute to disease tolerance [2]. However, helminth infections also induce changes to the gut microbiota that can have a systemic impact on heterologous infectious diseases [3]. Given previous studies demonstrating that the gut microbiota can shape disease tolerance to pulmonary infections [4], here, we discuss the current understanding of how the gut microbiota impacts TB and posit that helminth-mediated changes to this vast microbial community may contribute to the clinical course of TB in co-endemic regions (Fig 1). Open in a separate window Fig 1 Helminth infections, eliciting robust type 2 immune responses, might contribute to Mtb disease tolerance by inhibiting type 1 and type 3 immune responses, thus reducing inflammation and pathology while maintaining bacterial burden. An alternative, but not mutually exclusive, possibility is that helminth-mediated changes to the gut microbiota shape TB outcomes. The robust regulatory capacity of the gut microbiota (via immune suppression, metabolite processing, and niche competition) is an appealing mechanism to explain the contradicting data regarding the exact role of helminth infections in TB disease progression and disease tolerance in asymptomatic infected patients. This figure was created with BioRender.com. Mtb, Mycobacterium tuberculosis; TB, tuberculosis.

COVID-19 Antibody Detecting Rapid Diagnostic Tests Show High Cross-Reactivity When Challenged with Pre-Pandemic Malaria, Schistosomiasis and Dengue Samples.

COVID-19 Antibody Detecting Rapid Diagnostic Tests (COVID-19 Ab RDTs) are the preferred tool for SARS-CoV-2 seroprevalence studies, particularly in low- and middle-income countries. The present study challenged COVID-19 Ab RDTs with pre-pandemic samples of patients exposed to tropical pathogens. A retrospective study was performed on archived serum (n = 94) and EDTA whole blood (n = 126) samples obtained during 2010–2018 from 196 travelers with malaria (n = 170), schistosomiasis (n = 25) and dengue (n = 25). COVID-19 Ab RDTs were selected based on regulatory approval status, independent evaluation results and detecting antigens. Among 13 COVID-19 Ab RDT products, overall cross-reactivity was 18.5%; cross-reactivity for malaria, schistosomiasis and dengue was 20.3%, 18.1% and 7.5%, respectively. Cross-reactivity for current and recent malaria, malaria antibodies, Plasmodium species and parasite densities was similar. Cross-reactivity among the different RDT products ranged from 2.7% to 48.9% (median value 14.5%). IgM represented 67.9% of cross-reactive test lines. Cross-reactivity was not associated with detecting antigens, patient categories or disease (sub)groups, except for schistosomiasis (two products with ≥60% cross-reactivity). The high cross-reactivity for malaria, schistosomiasis and—to a lesser extent—dengue calls for risk mitigation when using COVID-19 Ab RDTs in co-endemic regions.

Natural infections with different Plasmodium species induce antibodies reactive to a chimeric Plasmodium vivax recombinant protein

BackgroundAs malaria incidence and transmission in a region decreases, it becomes increasingly difficult to identify areas of active transmission. Improved methods for identifying and monitoring foci of active malaria transmission are needed in areas of low parasite prevalence in order to achieve malaria elimination. Serological assays can provide population-level infection history to inform elimination campaigns.MethodsA bead-based multiplex antibody detection assay was used to evaluate a chimeric Plasmodium vivax MSP1 protein (PvRMC-MSP1), designed to be broadly immunogenic for use in vaccine studies, to act as a pan-malaria serological tool based on its ability to capture IgG in plasma samples obtained from naturally exposed individuals. Samples from 236 US travellers with PCR confirmed infection status from all four major Plasmodium species infecting humans, Plasmodium falciparum (n = 181), Plasmodium vivax (n = 38), Plasmodium malariae (n = 4), and Plasmodium ovale (n = 13) were tested for IgG capture using PvRMC-MSP1 as well as the four recombinant MSP1-19 kD isoforms representative of these Plasmodium species.ResultsRegardless of infecting Plasmodium species, a large proportion of plasma samples from infected US travellers provided a high assay signal to the PvRMC-MSP1 chimeric protein, with 115 high responders out of 236 samples assessed (48.7%). When grouped by active infection, 38.7% P. falciparum-, 92.1% of P. vivax-, 75.0% P. malariae-, and 53.4% of P. ovale-infected individuals displayed high assay signals in response to PvRMC-MSP1. It was also determined that plasma from P. vivax-infected individuals produced increased assay signals in response to the PvRMC-MSP1 chimera as compared to the recombinant PvMSP1 for 89.5% (34 out of 38) of individuals. PvRMC-MSP1 also showed improved ability to capture IgG antibodies from P. falciparum-infected individuals when compared to the capture by recombinant PvMSP1, with high assay signals observed for 38.7% of P. falciparum-infected travellers in response to PvRMC-MSP1 IgG capture compared to just 1.1% who were high responders to capture by the recombinant PvMSP1 protein.ConclusionsThese results support further study of designed antigens as an approach for increasing sensitivity or broadening binding capacity to improve existing serological tools for determining population-level exposure to Plasmodium species. Including both broad-reacting and Plasmodium species-specific antigen-coated beads in an assay panel could provide a nuanced view of population-level exposure histories, an extensive IgG profile, and detailed seroestimates. A more sensitive serological tool for detection of P. vivax exposure would aid malaria elimination campaigns in co-endemic areas and regions where P. vivax is the dominant parasite.

Real-time polymerase chain reaction based algorithm for differential diagnosis of Kinetoplastidean species of zoonotic relevance

Kinetoplastids are a group of flagellated protozoa that infect a vast repertoire of mammals and insect vectors. From a zoonotic point of view, domestic animals are critical reservoirs for transmission of Kinetoplastidean parasites. Due to their proximity to humans, they assume substantial epidemiological importance in the context of these zoonoses and consequently in public health. Their reliable identification is relevant to understand their eco-epidemiological involvement in transmission cycles. This work aimed to develop an algorithm based on sequential Real-Time PCR (qPCR) assays targeted to different loci (24S alpha rDNA, ITS1 and Hsp70) allowing distinction among Trypanosoma cruzi, Trypanosoma rangeli, Trypanosoma evansi and Leishmania species in biological samples collected from mammalian reservoirs and triatomine vectors. The algorithm includes a first qPCR test targeted to endogenous genes conserved within mammals and within triatomine vectors as internal controls of DNA sample integrity and/or qPCR inhibition. This algorithm was evaluated in biological samples from domestic cattle (N = 14), dogs (N = 19) and triatomines (N = 19). Analytical sensitivity of 24S alpha rDNA for detection of T. rangeli was 10 fg of DNA, with a linear range between 10 fg and 10 ng. For T. cruzi it varied depending on the Discrete typing unit. The ITS1 qPCR showed an analytical sensitivity of 100 pg/reaction and 100 fg/reaction of Leishmania spp. and T. evansi DNAs. In mammal field samples, four T. cruzi 24S alpha rDNA sequences and fourteen ITS1 amplicons specific for T. evansi were detected. qPCR-HRM analysis directed to the Hsp70 gene diagnosed two dogs with Leishmania infantum infection. Among 19 triatomine field samples, T. cruzi was detected in five; T. rangeli in eight and one specimen showed a mixed infection. This diagnostic algorithm can provide more accurate records of kinetoplastidean infection burden in vectors and reservoirs, relevant to update current eco-epidemiological maps in co-endemic regions.

Macrofilaricides: An Unmet Medical Need for Filarial Diseases.

Neglected parasitic helminth diseases such as onchocerciasis and lymphatic filariasis affect an estimated 145 million people worldwide, creating a serious health burden in endemic areas such as sub-Saharan Africa and India. Although these diseases are not usually lethal, these filarial nematodes, transmitted by blood-feeding insect vectors, cause severe debilitation and cause chronic disability to infected individuals. The adult worms can reproduce from 5 to up to 14 years, releasing millions of microfilariae, juvenile worms, over an infected individual's lifetime. The current treatments for controlling human filarial infections is focused on killing microfilariae, the earliest larval stage. Currently, there is an unmet medical need for treatments consisting of a macrofilaricidal regimen, one that targets the adult stage of the parasite, to increase the rate of elimination, allow for safe use in coendemic regions of Onchocerca volvulus and Loa loa, and to provide a rapid method to resolve reinfections. Herein, recent approaches for targeting human filarial diseases are discussed, including direct acting agents to target parasitic nematodes and antibacterial approaches to target the endosymbiotic bacteria, Wolbachia.

Stigma, participation restriction and mental distress in patients affected by leprosy, cutaneous leishmaniasis and Chagas disease: a pilot study in two co-endemic regions of eastern Colombia.

BackgroundLeprosy, cutaneous leishmaniasis (CL) and Chagas disease (CD) are neglected tropical diseases with a high psychosocial burden (PSB). These conditions are endemic in Norte de Santander and Arauca in Colombia, but data on the related PSB are scarce. Therefore, we assessed mental distress, participation restriction and stigma among CD, CL and leprosy patients.MethodsIn 2018, 305 leprosy, CD or CL patients were interviewed using a self-report questionnaire to assess mental distress, participation scale for participation restriction and explanatory model interview catalogue (EMIC) for stigma. Descriptive statistics and the significance of median score differences were compared.ResultsFifty percent of CD patients and 49% of leprosy patients exhibited mental distress, percentages which were significantly higher than that of CL (26%). Twenty-seven percent of leprosy patients experienced participation restriction, which was lower for CL (6%) and CD (12%). Median EMIC scores were significantly higher for leprosy patients than for CD (27%) and CL (17%) patients.ConclusionsWe found high levels of PSB among leprosy, CD and CL patients. Mental distress was highest among CD patients. Participation restriction and stigma were more prevalent in leprosy patients. Rural residence or lower educational status may impact PSB. Further investigation is needed to formulate evidence-based, holistic interventions.

Risk of Plasmodium vivax parasitaemia after Plasmodium falciparum infection: a systematic review and meta-analysis

SummaryBackgroundA 14-day course of primaquine is used for radical cure of Plasmodium vivax and Plasmodium ovale malaria only. We quantified the risk of P vivax parasitaemia after treatment of Plasmodium falciparum with commonly used antimalarial drugs to assess the potential benefits of radical cure for all patients with uncomplicated malaria in co-endemic regions.MethodsIn this systematic review and meta-analysis, we searched MEDLINE, Embase, Web of Science, and the Cochrane Database of Systematic Reviews for prospective clinical studies in any language, published between Jan 1, 1960, and Jan 5, 2018, assessing drug efficacy in patients with uncomplicated P falciparum malaria in countries co-endemic for P vivax. Studies were included if the presence or absence of P vivax parasitaemia was recorded after treatment. The primary outcome was the risk of P vivax parasitaemia between day 7 and day 42 after initiation of antimalarial treatment for P falciparum, with the pooled risk calculated by random-effects meta-analysis. We compared the risk of P vivax parasitaemia after treatment with different artemisinin-based combination therapies (ACTs). This study is registered with PROSPERO, number CRD42017064838.Findings153 of 891 screened studies were included in the analysis, including 31 262 patients from 323 site-specific treatment groups: 130 (85%) studies were from the Asia-Pacific region, 16 (10%) from the Americas, and seven (5%) from Africa. The risk of P vivax parasitaemia by day 42 was 5·6% (95% CI 4·0–7·4; I2=92·0%; 117 estimates). The risk of P vivax parasitaemia was 6·5% (95% CI 4·6–8·6) in regions of short relapse periodicity compared with 1·9% (0·4–4·0) in regions of long periodicity, and was greater after treatment with a more rapidly eliminated ACT: 15·3% (5·1–29·3) for artemether-lumefantrine compared with 4·5% (1·2–9·3) for dihydroartemisinin-piperaquine and 5·2% (2·9–7·9) for artesunate-mefloquine. Recurrent parasitaemia was delayed in patients treated with ACTs containing mefloquine or piperaquine compared with artemether-lumefantrine, but by day 63 the risk of vivax parasitaemia was more than 15% for all ACTs assessed.InterpretationOur findings show a high risk of vivax parasitaemia after treatment of falciparum malaria, particularly in areas with short relapse periodicity and after rapidly eliminated treatment. In co-endemic regions, universal radical cure for all patients with uncomplicated malaria has the potential to substantially reduce recurrent malaria.FundingAustralian National Health and Medical Research Council, Royal Australasian College of Physicians, Wellcome Trust, and Bill & Melinda Gates Foundation.

Contrasting Transmission Dynamics of Co-endemic Plasmodium vivax and P. falciparum: Implications for Malaria Control and Elimination.

BackgroundOutside of Africa, P. falciparum and P. vivax usually coexist. In such co-endemic regions, successful malaria control programs have a greater impact on reducing falciparum malaria, resulting in P. vivax becoming the predominant species of infection. Adding to the challenges of elimination, the dormant liver stage complicates efforts to monitor the impact of ongoing interventions against P. vivax. We investigated molecular approaches to inform the respective transmission dynamics of P. falciparum and P. vivax and how these could help to prioritize public health interventions.Methodology/ Principal FindingsGenotype data generated at 8 and 9 microsatellite loci were analysed in 168 P. falciparum and 166 P. vivax isolates, respectively, from four co-endemic sites in Indonesia (Bangka, Kalimantan, Sumba and West Timor). Measures of diversity, linkage disequilibrium (LD) and population structure were used to gauge the transmission dynamics of each species in each setting. Marked differences were observed in the diversity and population structure of P. vivax versus P. falciparum. In Bangka, Kalimantan and Timor, P. falciparum diversity was low, and LD patterns were consistent with unstable, epidemic transmission, amenable to targeted intervention. In contrast, P. vivax diversity was higher and transmission appeared more stable. Population differentiation was lower in P. vivax versus P. falciparum, suggesting that the hypnozoite reservoir might play an important role in sustaining local transmission and facilitating the spread of P. vivax infections in different endemic settings. P. vivax polyclonality varied with local endemicity, demonstrating potential utility in informing on transmission intensity in this species.Conclusions/ SignificanceMolecular approaches can provide important information on malaria transmission that is not readily available from traditional epidemiological measures. Elucidation of the transmission dynamics circulating in a given setting will have a major role in prioritising malaria control strategies, particularly against the relatively neglected non-falciparum species.

Does a significant reduction in malaria risk make lopinavir/ritonavir-based ART cost-effective for children with HIV in co-endemic, low-resource settings?

HIV infection and malaria co-infection is not uncommon among children in co-endemic regions, and evidence suggests that HIV is a risk factor for severe malaria among children. HIV protease inhibitors (PIs) are highly effective in pediatric HIV treatment regimens, however, their effectiveness against malaria has been mixed, with some PIs demonstrating in vitro activity against Plasmodium falciparum. Recent findings suggest lopinavir/ritonavir (LPV/r)-based treatment regimens reduce the incidence of malaria infection by over 40% in pediatric HIV patients compared to non-nucleoside reverse transcriptase inhibitor (NNRTI)-based regimens. We assessed whether a significant reduction in malaria risk makes LPV/r-based ART regimens cost-effective compared to NNRTI-based regimens in co-endemic, low-resource settings. We modeled the difference in unit cost per disability adjusted life year (DALY) gained among two theoretical groups of HIV+ children under 5 years old receiving ART in a resource-limited setting co-endemic for malaria. The first group received standard NNRTI-based antiretrovirals, the second group received a standard regimen containing LPV/r. We used recent cohort data for the incidence reduction for malaria. Drug costs were taken from the 2011 Clinton Health Access Initiative Antiretroviral (ARV) ceiling price list. DALYs for HIV and malaria were derived from WHO estimates. Our model suggests a unit cost of US$147 per DALY gained for the LPV/r-based group compared to US$37 per DALY gained for the NNRTI-based group. In HIV and malaria co-endemic settings, considerations of PI cost effectiveness incorporating known reductions in malaria mortality suggest a nominal increase in DALYs gained for PIs over NNRTI-based regimens for HIV positive children under five on ART. Our analysis was based on several assumptions due to lack of sound data on malaria and HIV DALY attribution among pediatric populations. Further study in this area is required.

Modelling Co-Infection with Malaria and Lymphatic Filariasis

Malaria and lymphatic filariasis (LF) continue to cause a considerable public health burden globally and are co-endemic in many regions of sub-Saharan Africa. These infections are transmitted by the same mosquito species which raises important questions about optimal vector control strategies in co-endemic regions, as well as the effect of the presence of each infection on endemicity of the other; there is currently little consensus on the latter. The need for comprehensive modelling studies to address such questions is therefore significant, yet very few have been undertaken to date despite the recognised explanatory power of reliable dynamic mathematical models. Here, we develop a malaria-LF co-infection modelling framework that accounts for two key interactions between these infections, namely the increase in vector mortality as LF mosquito prevalence increases and the antagonistic Th1/Th2 immune response that occurs in co-infected hosts. We consider the crucial interplay between these interactions on the resulting endemic prevalence when introducing each infection in regions where the other is already endemic (e.g. due to regional environmental change), and the associated timescale for such changes, as well as effects on the basic reproduction number R0 of each disease. We also highlight potential perverse effects of vector controls on human infection prevalence in co-endemic regions, noting that understanding such effects is critical in designing optimal integrated control programmes. Hence, as well as highlighting where better data are required to more reliably address such questions, we provide an important framework that will form the basis of future scenario analysis tools used to plan and inform policy decisions on intervention measures in different transmission settings.

Development of Three PCR Assays for the Differentiation between Echinococcus shiquicus, E. granulosus (G1 genotype), and E. multilocularis DNA in the Co-Endemic Region of Qinghai-Tibet plateau, China

To investigate echinococcosis in co-endemic regions, three polymerase chain reaction (PCR) assays based on the amplification of a fragment within the NADH dehydrogenase subunit 1 (ND1) mitochondrial gene were optimized for the detection of Echinococcus shiquicus, Echinococcus granulosus G1, and Echinococcus multilocularis DNA derived from parasite tissue or canid fecal samples. Specificity using parasite tissue-derived DNA was found to be 100% except for E. shiquicus primers that faintly detected E. equinus DNA. Sensitivity of the three assays for DNA detection was between 2 and 10 pg. Ethanol precipitation of negative PCR fecal samples was used to eliminate false negatives and served to increase sensitivity as exemplified by an increase in detection from 0% to 89% of E. shiquicus coproDNA using necropsy-positive fox samples.

Zoonotic Larval Cestode Infections: Neglected, Neglected Tropical Diseases?

Zoonotic Larval Cestode Infections: Neglected, Neglected Tropical Diseases?

TESA-blot for the diagnosis of Chagas disease in dogs from co-endemic regions for Trypanosoma cruzi, Trypanosoma evansi and Leishmania chagasi

We standardized serodiagnosis of dogs infected with Trypanosoma cruzi using TESA (trypomastigote excreted-secreted antigen)-blot developed for human Chagas disease. TESA-blot showed 100% sensitivity and specificity. In contrast, ELISA using TESA (TESA-ELISA) or epimastigotes (epi-ELISA) as antigen yielded 100% sensitivity but specificity of 94.1% and 49.4%, respectively. When used in field studies in an endemic region for Chagas disease, visceral leishmaniasis and Trypanosoma evansi (Mato Grosso do Sul state, Central Brazil), positivities were 9.3% for TESA-blot, 10.7% for TESA-ELISA and 32% for epi-ELISA. Dogs from a non-endemic region for these infections (Rondonia state, western Amazonia) where T. cruzi is enzootic showed positivity of 4.5% for TESA-blot and epi-ELISA and 6.8% for TESA-ELISA. Sera from urban dogs from Santos, São Paulo, where these diseases are absent, yielded negative results. TESA-blot was the only method that distinguished dogs infected with T. cruzi from those infected with Leishmania chagasi and/or Trypanosoma evansi.