Tropical Pathogens Research Articles

Reconciling Sustainability and Hygiene in the Healthcare Sector

In the course of climate change, doctors will not only be confronted with heat-related consequences, but also with the emergence of infectious diseases caused by previously tropical pathogens in temperate climate zones.Fortunately, the topics of sustainability and climate change are also becoming increasingly important in discussions in the healthcare sector, which accounts for 4.4% of global greenhouse gas emissions. The topic of hygienically safe sustainability in healthcare facilities is highly complex due to the large number of possible adjustments, but also offers a great deal of potential.Numerous measures can be implemented without any restrictions in terms of hygiene requirements or occupational safety.It is not always the large investments that make their contribution to reducing CO2-emissions - many smaller measures can also be implemented without high costs, but with great sustainability potential. Similar to hand hygiene compliance, behavior modification by each individual plays a decisive role in the implementation of such projects. There is great practical savings potential, for example, in the indication-based use of disposable medical gloves, the hygienically safe handling of medication or the decision between reusable and disposable medical products, just to name a few items discussed in the article.

The Incidence, Aetiology and Clinical Course of Serious Infections Complicating Biological and Targeted Synthetic Disease-Modifying Antirheumatic Drug Therapy in Patients with Rheumatoid Arthritis in Tropical Australia.

Introduction: Patients receiving biological and targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) for rheumatological conditions are at an increased risk of serious, potentially life-threatening, infection. However, the incidence, aetiology, and clinical course of serious infection in patients receiving b/tsDMARDs in tropical settings are incompletely defined. Methods: We retrospectively reviewed all patients with rheumatoid arthritis receiving b/tsDMARDs between October 2012 and October 2021, at Cairns Hospital in tropical Australia. The incidence, aetiology, and clinical course of serious infections (those requiring admission to hospital or parenteral antibiotics) were determined. Results: 310 patients had 1468 patient years of b/tsDMARD therapy during the study period; 74/310 (24%) had 147 serious infections translating to an overall risk of 10.0 episodes of serious infection per 100 patient years. The respiratory tract (50/147, 34%) and skin (37/147, 25%) were the most frequently affected sites. A pathogen was identified in 59/147 (40%) episodes and was most commonly Staphylococcus aureus (24/147, 16%). Only 2/147 (1%) were confirmed "tropical infections": 1 case of Burkholderia pseudomallei and 1 case of mixed B. pseudomallei and community-acquired Acinetobacter baumannii infection. Overall, 13/147 (9%) episodes of serious infection required Intensive Care Unit admission (0.9 per 100-patient years of b/tsDMARD therapy) and 4/147 (3%) died from their infection (0.3 per 100-patient years of b/tsDMARD therapy). The burden of comorbidity and co-administration of prednisone were the strongest predictors of death or a requirement for ICU admission. Conclusions: The risk of serious infection in patients taking b/tsDMARDs in tropical Australia is higher than in temperate settings, but this is not explained by an increased incidence of traditional tropical pathogens.

Detection of oomycete pathogens in UK peat-free growing media and implications for plant health

ABSTRACT Peat-based growing media products are being phased out in the UK. Alternative constituents may be at risk of harbouring oomycete plant pathogens. Thirty-five peat-free growing media samples were tested for oomycete pathogens by baiting and DNA metabarcoding. No Phytophthora species was detected by baiting, but seven species of Pythium, Phytopythium and Elongisporangium, including four species not previously reported in the UK, were baited. DNA matching eleven Phytophthora species was detected by metabarcoding across a range of samples. A coir sample was also found to contain DNA of Peronosclerospora, a genus of tropical downy mildew pathogens. DNA matching six Phytophthora pathogens, including P. bishii, a pathogen of strawberry not previously reported in the UK, was detected in recycled coir that had been used for strawberry production in The Netherlands. We discuss the implications of the species detected in terms of risks to plant health and the need for further evidence-gathering.

Development of methods to analyse Plasmodium falciparum single nucleotide polymorphisms in PfCRT (А > C), PfMDR1 (A > T) and PfDHFR (G > A) genes that determine resistance to quinoline, diamino-pyrimidine and sulfonamide groups of antimalarial drugs

BACKGROUND: The drug resistance of tropical malaria pathogens to mefloquine, chloroquine, pyrimethamine and their derivatives is associated with three single nucleotide polymorphisms: K76T (A403627C), S1034C (A960989T) and S108N (G748410A). These mutations are linked to changes in the structure of the PfCRT and PfMDR1 genes of Plasmodium falciparum.
 AIM: Develop methods for identifying single nucleotide polymorphisms that are suitable for early diagnosis of drug-resistant forms of tropical malaria.
 RESULTS: A method was developed based on restriction fragment length analysis using ApoI endonuclease to detect the K76T polymorphism (A403627C). The criterion for determining parasite resistance to chloroquine was the appearance of a single 145 bp band on the electropherogram. The genotype of the pathogens remained unchanged and their drug sensitivity was preserved, as indicated by the separation of two fragments of 98 and 47 bp.
 A system for detecting S108N (G748410A) was developed using the Bse1I endonuclease. The appearance of a single 507 bp band on the electropherogram indicated the mutant genotype of the pathogens, while the appearance of two fragments (323 and 184 bp) indicated an unchanged genotype and preservation of drug sensitivity of plasmodiae.
 To identify the A T polymorphism in the PfMDR1 gene at position 960989, polymerase chain reaction technology will be used with two allele-specific primers. One primer will detect the wild-type allele, and the other will detect the mutant genotype. The amplifiable fragment of the PfMDR1 gene contains sequences of the 1034th codon. Depending on the P. falciparum genotype, 261 bp fragments will be obtained with one of the allele-specific primers.
 CONCLUSION: Criteria for assessing drug resistance of P. falciparum were developed based on the analysis of obtained data. Haplotypes K76T (band 145 bp) and S1034C (band 262 bp with the direct primer S1034C-F2) serve as indicators of the relative resistance of pathogens to chloroquine, mefloquine, and their derivatives. Positive results of examination for haplotype S108N (bands 323 and 184 bp) should be considered as a sign of decreased sensitivity to pyrimethamine. The developed methods can be used in clinical practice and for epidemiological monitoring.

Purine nucleosides replace cAMP in allosteric regulation of PKA in trypanosomatid pathogens.

Cyclic nucleotide binding domains (CNB) confer allosteric regulation by cAMP or cGMP to many signaling proteins, including PKA and PKG. PKA of phylogenetically distant Trypanosoma is the first exception as it is cyclic nucleotide-independent and responsive to nucleoside analogues (Bachmaier et al., 2019). Here, we show that natural nucleosides inosine, guanosine and adenosine are nanomolar affinity CNB ligands and activators of PKA orthologs of the important tropical pathogens Trypanosoma brucei, Trypanosoma cruzi, and Leishmania. The sequence and structural determinants of binding affinity, -specificity and kinase activation of PKAR were established by structure-activity relationship (SAR) analysis, co-crystal structures and mutagenesis. Substitution of two to three amino acids in the binding sites is sufficient for conversion of CNB domains from nucleoside to cyclic nucleotide specificity. In addition, a trypanosomatid-specific C-terminal helix (αD) is required for high affinity binding to CNB-B. The αD helix functions as a lid of the binding site that shields ligands from solvent. Selectivity of guanosine for CNB-B and of adenosine for CNB-A results in synergistic kinase activation at low nanomolar concentration. PKA pulldown from rapid lysis establishes guanosine as the predominant ligand in vivo in T. brucei bloodstream forms, whereas guanosine and adenosine seem to synergize in the procyclic developmental stage in the insect vector. We discuss the versatile use of CNB domains in evolution and recruitment of PKA for novel nucleoside-mediated signaling.

Purine nucleosides replace cAMP in allosteric regulation of PKA in trypanosomatid pathogens

Cyclic nucleotide binding domains (CNB) confer allosteric regulation by cAMP or cGMP to many signaling proteins, including PKA and PKG. PKA of phylogenetically distant Trypanosoma is the first exception as it is cyclic nucleotide-independent and responsive to nucleoside analogues (Bachmaier et al., 2019). Here, we show that natural nucleosides inosine, guanosine and adenosine are nanomolar affinity CNB ligands and activators of PKA orthologs of the important tropical pathogens Trypanosoma brucei, Trypanosoma cruzi, and Leishmania. The sequence and structural determinants of binding affinity, -specificity and kinase activation of PKAR were established by structure-activity relationship (SAR) analysis, co-crystal structures and mutagenesis. Substitution of two to three amino acids in the binding sites is sufficient for conversion of CNB domains from nucleoside to cyclic nucleotide specificity. In addition, a trypanosomatid-specific C-terminal helix (αD) is required for high affinity binding to CNB-B. The αD helix functions as a lid of the binding site that shields ligands from solvent. Selectivity of guanosine for CNB-B and of adenosine for CNB-A results in synergistic kinase activation at low nanomolar concentration. PKA pulldown from rapid lysis establishes guanosine as the predominant ligand in vivo in T. brucei bloodstream forms, whereas guanosine and adenosine seem to synergize in the procyclic developmental stage in the insect vector. We discuss the versatile use of CNB domains in evolution and recruitment of PKA for novel nucleoside-mediated signaling.

Systematic study of 1,2,3-triazolyl sterols for the development of new drugs against parasitic Neglected Tropical Diseases

A series of thirty 1,2,3-triazolylsterols, inspired by azasterols with proven antiparasitic activity, were prepared by a stereocontrolled synthesis. Ten of these compounds constitute chimeras/hybrids of 22,26-azasterol (AZA) and 1,2,3-triazolyl azasterols. The entire library was assayed against the kinetoplastid parasites Leishmania donovani, Trypanosoma cruzi, and Trypanosoma brucei, the causatives agents for visceral leishmaniasis, Chagas disease, and sleeping sickness, respectively. Most of the compounds were active at submicromolar/nanomolar concentrations with high selectivity index, when compared to their cytotoxicity against mammalian cells. Analysis of in silico physicochemical properties were conducted to rationalize the activities against the neglected tropical disease pathogens. The analogs with selective activity against L. donovani (E4, IC50 0.78 μM), T brucei (E1, IC50 0.12 μM) and T. cruzi (B1– IC50 0.33 μM), and the analogs with broad-spectrum antiparasitic activities against the three kinetoplastid parasites (B1 and B3), may be promising leads for further development as selective or broad-spectrum antiparasitic drugs.

Identification and characterization of biocontrol agent Lysinibacillus boronitolerans P42 against Cerrena unicolor that causes root rot of arecanut palm

The arecanut palm is one of the most important industrial crops in tropical area around the world. The root rot of arecanut palm, which is caused by Cerrena unicolor, has led to heavy economic losses and restricted greatly the development of arecanut industry, especially in Hainan province of China. The common use of chemical agents has worsened the problems of the emergence of resistant pathogens and the pollution of agricultural environment. This study aims to screen and identify a more effective and environment friendly biocontrol method for the prevention and treatment of root rot of arecanut palm. The mycelium growth rate is investigated to select antagonistic bacteria from tropical crop rotation fields which show improved resistance against soil-borne pathogens, and the strain P42 is revealed with the strongest antagonistic effects (82.18%). Based on 16s rDNA sequence analysis, the strain P42 is identified as Lysinibacillus boronitolerans. In vitro antimicrobial activity shows that the strain P42 exhibits broad-spectrum antagonistic activity against a wide variety of tropical agricultural fungal pathogens, including Cerrena unicolor, Magnaporthe oryzea, Botryodiplodia theobromae, Neoscytalidium dimidiatum, Thanatephorus cucumeris, Fusarium oxysporum, and Botrytis cinereaPer.. The antagonistic activity of the culture of P42 is tolerant to common proteases, longer storage time, and temperature range of 40-121°C; and is significantly influenced by alkaline (7-9) and acidic (1-2) pH, as well as by ultraviolet ray treatment for more than 30min. The investigation on the antagonistic activity of the crude extract of fermentation filtrate indicates that the active compounds might be lipopeptides, polyketones, or proteins. To our knowledge, this is the first report of L. boronitolerans as potential bio-reagents for controlling root rot of arecanut palm caused by Cerrena unicolor.

2356. Standardizing a centralized allocation process for rarely used anti-infective medications across a health system

Abstract Background Obtaining scarce antimicrobials used to treat infrequently encountered infections such as malaria have posed a challenge to clinicians and health systems. Due to the rare occurrence of these infections, maintaining adequate, readily available supply for emergent need is challenging, and a lack of clear procurement processes from regional storage sites may contribute to delays in care. In March 2021, artesunate became commercially available for the treatment of severe malaria, a disease for which prompt initiation of therapy is paramount. To improve access to this and other critical but seldom used medications, a centralized storage and allocation process was established throughout our 10-hospital health system. We aim to describe the structure of this program which may serve as a model for other institutions to expedite and streamline access to these lifesaving therapies. Tracking document for therapy supply management. Methods In May 2021, a centralized process was created to track and store rare anti-infective medications for uncommon infections, including those caused by tropical, parasitic, and mycobacterial pathogens (Table 1). Supply is monitored and maintained by clinical pharmacists monthly to ensure adequate courses are available. When needed for a specific patient, infectious diseases physicians and pharmacists recommend therapy which triggers a request to the central pharmacy. Results Medications are stored at our large academic medical center (AMC), which manages these cases more routinely compared to other sites. Community hospitals within the health system are able to contact the AMC for prompt distribution of these medications when needed. Since its inception, we have deployed rare use anti-infective medications to partner facilities twice for severe malaria cases, which resulted in expedited receipt of therapy for critically ill patients. The time from therapy recommendation to medication administration was reduced from 12–24 hours to 2–6 hours. Conclusion This centralized rare anti-infective medication process expedites and streamlines access for critical therapeutic agents to ensure they are readily available when needed by limiting procurement/storage concerns. This model may be used as a framework for other medications for which timely administration, but rare use, is critical to patient care. Disclosures All Authors: No reported disclosures.

Diversity and antimicrobial activity of marine nudibranch associated bacteria against tropical human skin pathogens

Background: Skin disease is the fourth most common disease among all diseases. The number of cases of skin diseases continues to increase, and people commonly use antibiotics to treat these diseases. Nevertheless, overuse of antibiotics can increase the resistance of these pathogens. Hence, the study of novel antibiotic compounds against multi-drug resistant (MDR) skin pathogens is urgently needed. Methods: This study describes the antimicrobial diversity of bacteria associated with three species of marine nudibranchs (Jorunna funebris, Gymnodoris rubropapulosa, and Glossodoris atromarginata) sampled from Jepara coastal waters, the North Java Sea in August 2020. A total of 115 bacterial strains were selected for their prospective antipathogenic compounds against the pathogens Cutibacterium acnes, Staphylococcus aureus, Candida albicans, and Malassezia furfur. Results: A total of 24 bacterial isolates (20.87%) exhibited antimicrobial activity against the pathogens that were selected and molecularly identified. Analyses of the gene of 16S rRNA discovered that these 24 isolates were associated with 11 genera of the phyla Firmicutes, Proteobacteria, and Actinobacteria, including Bacillus as the dominant genus, followed by Streptomyces, Gordonia, Salinicola, Thalassospira, Halomonas, Dietzia, Brevibacterium, Paracoccus, Pseudovibrio, Pseudoalteromonas, and Pseudomonas. None of the 24 antimicrobial bacterial strains possessed type-1 polyketide synthases (PKS-I). One strain possessed type II polyketide synthases (PKS-II), and five strains possessed non-ribosomal peptide synthetase (NRPS) genes. The amounts of bacterial genus and strains in the three nudibranchs differed significantly, as did the proportions of antimicrobial strains in each nudibranch species. The antibacterial strains isolated from G. atromarginata were the highest number (62.5%), followed by J. funebris (20.8%) and G. rubropapulosa (16.7%). Conclusions: These results demonstrate that nudibranch species harbor prominent and varied communities of bacteria and reveal that many nudibranch-associated bacteria have the potential for the advancement of broad-spectrum antibiotics.

Virusbedingte Exantheme nach Fernreisen

Dermatologische Erkrankungen gehören zu den häufigsten reiseassoziierten Erkrankungen. Einen großen Stellenwert haben insbesondere virale Infektionen mit tropischen und subtropischen, aber auch hierzulande vorkommenden Erregern, die häufig mit Exanthemen und Allgemeinsymptomen einhergehen. Neben genauen anamnestischen Angaben über den Reiseverlauf und mögliche Risikoexpositionen sowie einer gründlichen klinischen Untersuchung ist insbesondere die Kenntnis über länderspezifische Risiken wichtig, um in Kombination mit molekularbiologischen und serologischen Untersuchungen die korrekte Diagnose zu stellen. Anhand eines Fallbeispiels gibt dieser Beitrag eine Übersicht über wichtige virusbedingte Exantheme, die insbesondere bei Reiserückkehrern auftreten können.

Diversity and antimicrobial activity of marine nudibranch associated bacteria against tropical human skin pathogens

Background: Skin disease is the fourth most common disease among all diseases. The number of cases of skin diseases continues to increase, and people commonly use antibiotics to treat these diseases. Nevertheless, overuse of antibiotics can increase the resistance of these pathogens. Hence, the study of novel antibiotic compounds against multi-drug resistant (MDR) skin pathogens is urgently needed. Methods: This study describes the antimicrobial diversity of bacteria associated with three species of marine nudibranchs (Jorunna funebris, Gymnodoris rubropapulosa, and Glossodoris atromarginata) sampled from Jepara coastal waters, the North Java Sea in August 2020. A total of 115 bacterial strains were selected for their prospective antipathogenic compounds against the pathogens Cutibacterium acnes, Staphylococcus aureus, Candida albicans, and Malassezia furfur. Results: A total of 24 bacterial isolates (20.87%) exhibited antimicrobial activity against the pathogens that were selected and molecularly identified. Analyses of the gene of 16S rRNA discovered that these 24 isolates were associated with 11 genera of the phyla Firmicutes, Proteobacteria, and Actinobacteria, including Bacillus as the dominant genus, followed by Streptomyces, Gordonia, Salinicola, Thalassospira, Halomonas, Dietzia, Brevibacterium, Paracoccus, Pseudovibrio, Pseudoalteromonas, and Pseudomonas. None of the 24 antimicrobial bacterial strains possessed type-1 polyketide synthases (PKS-I). One strain possessed type II polyketide synthases (PKS-II), and five strains possessed non-ribosomal peptide synthetase (NRPS) genes. The amounts of bacterial genus and strains in the three nudibranchs differed significantly, as did the proportions of antimicrobial strains in each nudibranch species. The antibacterial strains isolated from G. atromarginata were the highest number (62.5%), followed by J. funebris (20.8%) and G. rubropapulosa (16.7%). Conclusions: These results demonstrate that nudibranch species harbor prominent and varied communities of bacteria and reveal that many nudibranch-associated bacteria have the potential for the advancement of broad-spectrum antibiotics.

The epidemiology and outcomes of central nervous system infections in Far North Queensland, tropical Australia; 2000-2019.

The epidemiology of central nervous system (CNS) infections in tropical Australia is incompletely defined. A retrospective study of all individuals in Far North Queensland, tropical Australia, who were diagnosed with a CNS infection between January 1, 2000, and December 31, 2019. The microbiological aetiology of the infection was correlated with patients' demographic characteristics and their clinical course. There were 725 cases of CNS infection during the study period, meningitis (77.4%) was the most common, followed by brain abscess (11.6%), encephalitis (9.9%) and spinal infection (1.1%). Infants (24.3%, p<0.0001) and Aboriginal and Torres Strait Islander Australians (175/666 local residents, 26.3%, p<0.0001) were over-represented in the cohort. A pathogen was identified in 513 cases (70.8%); this was viral in 299 (41.2%), bacterial in 175 (24.1%) and fungal in 35 (4.8%). Cryptococcal meningitis (24 cases) was diagnosed as frequently as pneumococcal meningitis (24 cases). There were only 2 CNS infections with a S. pneumoniae serotype in the 13-valent pneumococcal vaccine after its addition to the National Immunisation schedule in 2011. Tropical pathogens-including Cryptococcus species (9/84, 11%), Mycobacterium tuberculosis (7/84, 8%) and Burkholderia pseudomallei (5/84, 6%)-were among the most common causes of brain abscess. However, arboviral CNS infections were rare, with only one locally acquired case-a dengue infection in 2009-diagnosed in the entire study period. Intensive Care Unit admission was necessary in 14.3%; the overall case fatality rate was 4.4%. Tropical pathogens cause CNS infections as commonly as traditional bacterial pathogens in this region of tropical Australia. However, despite being highlighted in the national consensus guidelines, arboviruses were identified very rarely. Prompt access to sophisticated diagnostic and supportive care in Australia's well-resourced public health system is likely to have contributed to the cohort's low case-fatality rate.

Coinfection With SARS-CoV-2 and Dengue Virus: A Case Report Highlighting Diagnostic Challenges.

Since its emergence in China, SARS-CoV-2 has infected more than 240 million people worldwide, including in regions where dengue virus (DENV) is hyperendemic such as Latin America and Southeast Asia, including Indonesia. Diagnosis of COVID-19 in dengue endemic regions as well as DENV and SARS-CoV-2 co-infection can be challenging. We describe a 68-year-old woman with diabetes mellitus type II who was admitted to the Tangerang District Hospital on 14 April 2020. She lived in a neighborhood where a few people were contracting dengue fever. She presented with five days of fever, malaise, anorexia, nausea, myalgia, and arthralgia. Hematology revealed anemia, thrombocytopenia, normal leukocyte count, increased neutrophil proportion, and decreased lymphocyte proportion and absolute lymphocytes. Her chest X-ray showed right pericardial infiltrates. Although dengue was clinically suspected, she was also tested for SARS-CoV-2 infection as she met screening criteria. After being confirmed SARS-CoV-2 positive by RT-PCR, she was treated with ceftriaxone, paracetamol, azithromycin, oseltamivir, and chloroquine. She was clinically improved four days later and discharged from the hospital on 25 April 2020 after SARS-CoV-2 RT-PCR was negative on two consecutive samples. Dengue was diagnosed retrospectively based on sero-conversion of dengue IgM and a very high dengue IgG index (ELISA, Focus Diagnostics®, Cypress, CA, USA), and sero-conversion of dengue IgM and positive IgG (Rapid test, PanBio ®Dengue duo cassette, Inverness Medical Innovations, QLD, AU), which was equivalent to high Hemagglutination Inhibition (HI) antibody titer (≥1280) found in secondary dengue infection. The overlapping clinical presentations of COVID-19 and dengue; limited diagnostic capacity of laboratories in resource constrained settings; and complexities of interpreting results make identification of COVID-19 in the dengue endemic setting challenging. Clinicians in endemic areas must be aware of diagnostic challenges and maintain a high index of suspicion for COVID-19 coinfection with DENV and other tropical pathogens.

Pathogen-Induced Epigenetic Modifications in Cancers: Implications for Prevention, Detection and Treatment of Cancers in Africa.

Cancer is a major public health burden worldwide. Tumor formation is caused by multiple intrinsic and extrinsic factors. Many reports have demonstrated a positive correlation between the burden of infectious pathogens and the occurrence of cancers. However, the mechanistic link between pathogens and cancer development remains largely unclear and is subject to active investigations. Apart from somatic mutations that have been widely linked with various cancers, an appreciable body of knowledge points to alterations of host epigenetic patterns as key triggers for cancer development. Several studies have associated various infectious pathogens with epigenetic modifications. It is therefore plausible to assume that pathogens induce carcinogenesis via alteration of normal host epigenetic patterns. Thus, Africa with its disproportionate burden of infectious pathogens is threatened by a dramatic increase in pathogen-mediated cancers. To curb the potential upsurge of such cancers, a better understanding of the role of tropical pathogens in cancer epigenetics could substantially provide resources to improve cancer management among Africans. Therefore, this review discusses cancer epigenetic studies in Africa and the link between tropical pathogens and cancer burden. In addition, we discuss the potential mechanisms by which pathogens induce cancers and the opportunities and challenges of tropical pathogen-induced epigenetic changes for cancer prevention, detection and management.

Historical Spatial Distribution of Zoonotic Diseases in Domestic, Synanthropic, and Wild Animals in the Mexican Territory of the Yucatan Peninsula.

The Mexican territory of the Yucatan Peninsula has a tropical climate and harbors a wide variety of domestic, synanthropic, and wild animals, as well as disease vectors. To determine the distribution of recorded zoonotic diseases in the Yucatan Peninsula, scientific publications referring to these diseases in animals and containing geographic coordinates of disease occurrence, were studied. The epidemiological bulletins of the national government were also consulted to obtain information on zoonotic diseases reported in humans in the territory. The territory harbors a wide variety of tropical zoonotic pathogens, including Trypanosoma cruzi, Leptospira interrogans, Toxoplasma gondii, Leishmania mexicana, Dirofilaria immitis, and Rickettsia felis. A variety of domestic, synanthropic, and wild animals act as hosts or reservoirs in the transmission cycle of the zoonotic diseases in the Yucatan Peninsula, and some spillover into human populations has also been recorded. There are still zoonotic diseases that have rarely or never been reported in humans, but it is not clear whether this is because these diseases in humans are not common, there is a lack of viable transmission cycle or there is a lack of appropriate diagnosis. It is necessary to continue monitoring vectors, animal hosts, and humans to identify risk factors for zoonotic diseases in the Yucatan Peninsula.

Comparison of Three In-House Real PCR Assays Targeting Kinetoplast DNA, the Small Subunit Ribosomal RNA Gene and the Glucose-6-Phosphate Isomerase Gene for the Detection of Leishmania spp. in Human Serum.

To perform PCR from serum for the diagnosis of visceral leishmaniasis is convenient and much less invasive than the examination of deeper compartments such as bone marrow. We compared three Leishmania-specific real-time PCRs with three different molecular targets (kinetoplast DNA, the small subunit-ribosomal RNA-(ssrRNA-)gene, the glucose-6-phosphate isomerase-(gpi-)gene) regarding their sensitivity and specificity in human serum. Residual sera from previous diagnostic assessments at the German National Reference Center for Tropical Pathogens Bernhard Nocht Institute for Tropical Medicine Hamburg and the Swiss Tropical and Public Health Institute were used. The sensitivities of kinetoplast DNA-PCR, ssrRNA-gene PCR, and gpi-PCR were 93.3%, 73.3%, and 33.3%, respectively, with 15 initial serum samples from visceral leishmaniasis patients, as well as 9.1%, 9.1%, and 0.0%, respectively, with 11 follow-up serum samples taken at various time points following anti-leishmanial therapy. Specificity was 100.0% in all assays as recorded with 1.137 serum samples from deployed soldiers and migrants without clinical suspicion of visceral leishmaniasis. Kinetoplast-DNA PCR from serum was confirmed as a sensitive and specific approach for the diagnosis of visceral leishmaniasis. The results also indicate the suitability of serum PCR for diagnostic follow-up after therapy, in particular regarding therapeutic failure in case of persisting positive PCR results.

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.

Parasitic dermatoses from abroad

Increased migration, the omnipresent desire to travel, climate change and aglobally more mobile population enhance the risk of spreading infectious, tropical pathogens across international borders. In addition to diarrhea and fever, skin diseases present one of the most common reasons for amedical consultation upon return among travelers. These diseases are often caused by parasites. Detailed data on infectious travel diseases is scarce. However, demographic, endemic and travel-related information represent the basic requirements for physicians to choose appropriate diagnostics and adequate treatment for affected patients. This article gives an overview of common parasitic travel dermatoses, their specific diagnostic workup, treatment and preventive measures.

The RNAi as a tool to control tropical pathogens

Introduction. Sustainable farming requires new tools for the control of pathogens, since there is a constant evolution to overcome the current biological and chemical strategies. The information provided by the transcriptomics allows creating new possibilities to tackle the pathogens. It is possible to interrupt the genetic expression of a pathogen and disable it using RNA interference (RNAi). Objective. To perform an analysis of an emerging technology useful for pest control, based on RNA interference. Development. Sustainable farming is measured based through social, economic, and environmental indicators. A key indicator of agriculture is the decrease in inputs for the control of pathogens and the increase in their specificity. Pest control mechanisms based on RNA interference meet both parameters. RNAi is known to have at least two functions, first for gene expression regulation, and secondly as a defense mechanism against pathogens. Consequently, RNAi can be used to protect crops from pathogens by developing genetically modified plants, or by the external application form of an aerosol. The RNAi aerosol is a tool that relies on inactivating the pathogen genes and can complement other agronomic tools available for this purpose. It is possible to design RNAi against tropical pests based on published transcriptomes, although it is necessary to overcome limitations regarding design, degradation, and stability. Conclusion. Interference RNA methods have the potential to be useful tools to control tropical pathogens as an alternative to achieve sustainable farming.