Infections In Tropical Regions Research Articles

Step towards elimination of Wuchereria bancrofti in Southwest Tanzania 10 years after mass drug administration with Albendazole and Ivermectin.

BackgroundLymphatic filariasis is a mosquito transmitted parasitic infection in tropical regions. Annual mass treatment with ivermectin and albendazole is used for transmission control of Wuchereria bancrofti, the infective agent of lymphatic filariasis in many African countries, including Tanzania.MethodologyIn a general population study in Southwest Tanzania, individuals were tested for circulating filarial antigen, an indicator of W. bancrofti adult worm burden in 2009 before mass drug administration commenced in that area. Seven annual rounds with ivermectin and albendazole were given between 2009 and 2015 with a population coverage of over 70%. Participants of the previous study took part in a follow-up activity in 2019 to measure the effect of this governmental activity.FindingsOne thousand two hundred and ninety nine inhabitants of Kyela district in Southwest Tanzania aged 14 to 65 years who had participated in the study activities in 2009 were revisited in 2010/11 and 2019. Among this group, the prevalence of lymphatic filariasis of the 14–65 years olds in 2009 was 35.1%. A follow-up evaluation in 2010/11 had shown a reduction to 27.7%. In 2019, after 7 years of annual treatment and an additional three years of surveillance, the prevalence had dropped to 1.7%, demonstrating successful treatment by the national control programme. Risk factors for W. bancrofti-infection were the occupation as farmer, male sex, and older age. Most infected individuals in the 2019 follow-up study already had a positive test for filarial antigen in 2009 and/or 2010/11.ConclusionsThis data supports the findings of the Tanzanian Neglected Tropical Disease Control Programme (NTDCP), who conducted Transmission Assessment Surveys and found an impressive reduction in the prevalence of LF in children. Our results complement this data by showing a similar decrease in prevalence of LF in the adult population in the same area. The elimination of LF seems achievable in the near future.

Electrocardiographic abnormalities in prevalent infections in tropical regions

Cardiovascular manifestations and electrocardiographic abnormalities have been reported among some prevalent infections in tropical regions, which lead to a great amount of morbidity and mortality. The major infectious diseases include chikungunya, dengue fever, H1N1 influenza, and coronavirus disease-19 (COVID- 19) in the viral category, leptospirosis, salmonellosis, scrub typhus and tuberculosis in the bacterial category, and malaria in the protozoan parasite category. All these infirmities constitute a foremost infection burden worldwide and have been linked to the various cardiac rhythm aberrancies. So we aimed to identify and compile different studies on these infections and associated acute electrocardiographic (ECG) changes. The search was made in online international libraries like PubMed, Google Scholar, and EMBASE, and 38 most relevant articles, including original research, systematic reviews, and unique case reports were selected. All of them were evaluated thoroughly and information regarding ECG was collected. Myocarditis is the predominant underlying pathology for rhythm disturbance and can be affected either due to the direct pathogenic effect or the abnormal immune system activation. ECG variabilities in some infections like chikungunya, scrub typhus, and leptospirosis are associated with longer hospital stay and poor outcome. Tropical infective diseases are associated with prominent acute cardiac rhythm abnormalities due to myocarditis, which can be identified preliminarily by ECG changes.

Antibiotic susceptibility of clinical Burkholderia pseudomallei isolates in northeast Thailand during 2015-2018 and the genomic characterization of β-lactam-resistant isolates.

Melioidosis is an often fatal infection in tropical regions caused by an environmental bacterium, Burkholderia pseudomallei Current recommended melioidosis treatment requires intravenous β-lactam antibiotics such as ceftazidime (CAZ), meropenem (MEM) or amoxicillin-clavulanic acid (AMC) and oral trimethoprim-sulfamethoxazole. Emerging antibiotic resistance could lead to therapy failure and high mortality. We performed a prospective multicentre study in northeast Thailand during 2015-2018 to evaluate antibiotic susceptibility and characterize β-lactam resistance in clinical B. pseudomallei isolates. Collection of 1,317 B. pseudomallei isolates from patients with primary and relapse infections were evaluated for susceptibility to CAZ, imipenem (IPM), MEM and AMC. β-lactam resistant isolates were confirmed by broth microdilution method and characterized by whole genome sequence analysis, penA expression and β-lactamase activity. The resistant phenotype was verified via penA mutagenesis. All primary isolates were IPM-susceptible but we observed two CAZ-resistant and one CAZ-intermediate resistant isolates, two MEM-less susceptible isolates, one AMC-resistant and two AMC-intermediate resistant isolates. One of 13 relapse isolates was resistant to both CAZ and AMC. Two isolates were MEM-less susceptible. Strains DR10212A (primary) and DR50054E (relapse) were multi-drug resistant. Genomic and mutagenesis analyses supplemented with gene expression and β-lactamase analyses demonstrated that CAZ-resistant phenotype was caused by PenA variants: P167S (N=2) and penA amplification (N=1). Despite the high mortality rate in melioidosis, our study revealed that B. pseudomallei isolates had a low frequency of β-lactam resistance caused by penA alterations. Clinical data suggest that resistant variants may emerge in patients during antibiotic therapy and be associated with poor response to treatment.

Aetiological profile of fever in neonatal and paediatric population in hospital setting

Background: Febrile illness in children is a common cause of admission to hospital globally, with significant associated morbidity and mortality. Dengue, malaria, scrub typhus, typhoid and leptospirosis have been identified as major causes of acute undifferentiated febrile illness in Thailand, Malaysia, and Nepal. Climate variation, over population and urbanization may all contribute to the emergence and reemergence of infections in tropical regions like Tamil Nadu. The objectives of this study were to describe the aetiology of fever in hospitalized neonatal and Pediatric population. A descriptive study was designed.Methods: A prospective observational study was conducted. All children from 0 to 18 years admitted as in-patients. Sample size was calculated to be 650. Basic laboratory tests were done in all cases.Results: Out of a total of 650 children maximum number (40.7% n=265) of patients had short duration of fever between 1 to 3 days. Majority (56%) of patients had temperature between 100.4 to 101F. Only 5 children were confirmed to have malaria. Maximum number of pus cells found was 80 to 100 in 3 children in urine examination. Total Infectious cases were 631 (97.07%).Conclusions: Infectious aetiology was more common than non-infectious aetiology. Among all aetiologies, viral fever particularly dengue was the most common aetiology. Enteric fever was the second most common infectious cause of fever after viral fever. Short febrile illness (1 to 5 days) was the most common type of fever in children admitted in hospital. In neonates, the most common cause of fever was probable sepsis followed by dehydration fever.

Biochemical and Molecular Effects of <i>Phoenix dactylifera</i> and <i>Ziziphus spina-christi</i> Extracts on <i>Candida albicans</i>

Our overall knowledge of the medicinal uses of plants suggests that natural compounds could be useful in the treatment of cutaneous fungal infections in tropical regions. Furthermore, the possibilities of treatment using plant extracts may be even broader than is already known when one considers plants that have not been extensively studied in this context, such as the regional species Phoenix dactylifera and Ziziphus spina-christi. This study compared the antimicrobial activity of Phoenix dactylifera and Ziziphus spina-christi extracts in terms of their biochemical and molecular effects on Candida albicans (ATCC CA 10231). These effects included altered levels of intracellular sterols, changes in the permeability of the cell membrane, and changes in the TEF1: QRTTEF1, CaERG1: ERG1, CdERG12: CdERG1, and ERG25: ERG25 genes. Scanning electron microscopy (SEM) was used to identify morphological characteristics, and energy-dispersive X-ray spectroscopy (EDAX) analyses were conducted. In treated samples, the SEM and EDAX analyses showed cell cavities and shrinkage of the cell wall, and the number of cells was reduced to only a few abnormal cells as compared with that in the untreated samples. Yttrium was detected in the cells treated with Z. spina-christi, and high levels of osmium were detected in the cells treated with P. dactylifera. Compared with control cells, cells exposed to the concentration 150 μl/ml of Z. spina-christi extract had an average sterol concentration that was nearly 3 times higher, while the concentration was 5.5 times higher for cells treated with the 150 μl/ml of P. dactylifera extract. The ethanol extracts affected the permeability of C. albicans cell membrane. Gene sequencing showed gaps and mismatches in the ERG1, ERG12, and ERG25 genes after treatment with P. dactylifera and Z. spina-christi extracts compared with that in the controls. The results were highly significant (p ≤ 0.01). We conclude that the ethanol extracts of P. dactylifera and Z. spina-christi have antimicrobial activity through several mechanisms in the yeast cell.

Comprehensive analysis of clinical Burkholderia pseudomallei isolates demonstrates conservation of unique lipid A structure and TLR4-dependent innate immune activation

Burkholderia pseudomallei is an environmental bacterium that causes melioidosis, a major community-acquired infection in tropical regions. Melioidosis presents with a range of clinical symptoms, is often characterized by a robust inflammatory response, may relapse after treatment, and results in high mortality rates. Lipopolysaccharide (LPS) of B. pseudomallei is a potent immunostimulatory molecule comprised of lipid A, core, and O-polysaccharide (OPS) components. Four B. pseudomallei LPS types have been described based on SDS-PAGE patterns that represent the difference of OPS–type A, type B, type B2 and rough LPS. The majority of B. pseudomallei isolates are type A. We used matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) followed by electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QqTOF MS) and gas chromatography to characterize the lipid A of B. pseudomallei within LPS type A isolates. We determined that B. pseudomallei lipid A is represented by penta- and tetra-acylated species modified with 4-amino-4-deoxy-arabinose (Ara4N). The MALDI-TOF profiles from 171 clinical B. pseudomallei isolates, including 68 paired primary and relapse isolates and 35 within-host isolates were similar. We did not observe lipid A structural changes when the bacteria were cultured in different growth conditions. Dose-dependent NF-κB activation in HEK cells expressing TLR4 was observed using multiple heat-killed B. pseudomallei isolates and corresponding purified LPS. We demonstrated that TLR4-dependent NF-κB activation induced by heat-killed bacteria or LPS prepared from OPS deficient mutant was significantly greater than those induced by wild type B. pseudomallei. These findings suggest that the structure of B. pseudomallei lipid A is highly conserved in a wide variety of clinical and environmental circumstances but that the presence of OPS may modulate LPS-driven innate immune responses in melioidosis.

Deep cutaneous fungal infection in tropical regions: A retrospective study from a referral center in southern Taiwan

Deep cutaneous fungal infection in tropical regions: A retrospective study from a referral center in southern Taiwan

Cutaneous manifestations of subcutaneous and systemic fungal infections in tropical regions: a retrospective study from a referral center in southern Taiwan.

Deep cutaneous fungal infections, including subcutaneous mycoses and systemic fungal infection with cutaneous involvement, cause significant morbidity and mortality in light of increasing immunocompromised patients and global warming. Although a few studies reviewed deep fungal infections in temperate regions, a relevant study in tropical regions is lacking. We evaluated features of deep cutaneous fungal infections in southern Taiwan among the tropical regions. We retrospectively reviewed all histopathological specimens with deep cutaneous fungal infections in a single referral center from 2001 to 2014 and successfully identified 23 cases. Medical chart review revealed patient demographic data, clinical presentation, underlying disease, microbiological culture reports, and treatment outcomes. The average patient age was 52 years. Fourteen cases had primary subcutaneous mycoses, and nine had systemic mycoses. Fifteen patients were immunocompromised, including hematological malignancies. Acquired immune deficiency syndrome (AIDS) and long-term steroid use were most commonly associated with deep fungal infections. The positive culture growth rate was 63%. Fonsecaea sp. was most frequently identified by tissue culture. Aspergillosis, mucormycosis, and disseminated cryptococcosis were particularly fatal. Diabetes and long-term steroid use appear as major risk factors for advanced mycoses in this region. Rapid diagnosis with skin biopsy and tissue culture along with appropriate treatment of deep cutaneous fungal infection are necessary.

The panorama of animal leptospirosis in Rio de Janeiro, Brazil, regarding the seroepidemiology of the infection in tropical regions

BackgroundLeptospirosis is an important disease caused by various serovars of Leptospira sp. It can affect humans as well as domestic and wild animals; therefore, it has importance for public health, animal production, and wild species. The aim of this paper is to discuss the epidemiology of animal leptospirosis in Rio de Janeiro, Brazil, as a possible model for other tropical regions. In several studies conducted in the last 20 years, a total of 47 rats, 120 dogs, 875 cows, 695 horses, 1,343 goats, 308 sheep and 351 pigs from all regions of the state, in addition to 107 wild mammals and 73 golden-lion tamarins were tested (MAT) for anti-Leptospira antibodies.ResultsSeroreactivity was frequent in all studied species, confirming that the infection is endemic in Rio de Janeiro. Serogroups Icterohaemorrhagiae and Sejroe were the most prevalent in urban and rural scenarios, respectively. This paper reviews the current knowledge on animal leptospirosis in Rio de Janeiro and describes important differences between urban versus rural cycles of the infection in various species.ConclusionIdentification of the prevailing serogroups and their reservoirs is essential for understanding agent-host-environment interactions under tropical conditions.

Is ultra-violet radiation the main force shaping molecular evolution of varicella-zoster virus?

BackgroundVaricella (chickenpox) exhibits a characteristic epidemiological pattern which is associated with climate. In general, primary infections in tropical regions are comparatively less frequent among children than in temperate regions. This peculiarity regarding varicella-zoster virus (VZV) infection among certain age groups in tropical regions results in increased susceptibility during adulthood in these regions. Moreover, this disease shows a cyclic behavior in which the number of cases increases significantly during winter and spring. This observation further supports the participation of environmental factors in global epidemiology of chickenpox. However, the underlying mechanisms responsible for this distinctive disease behavior are not understood completely. In a recent publication, Philip S. Rice has put forward an interesting hypothesis suggesting that ultra-violet (UV) radiation is the major environmental factor driving the molecular evolution of VZV.DiscussionWhile we welcomed the attempt to explain the mechanisms controlling VZV transmission and distribution, we argue that Rice's hypothesis takes lightly the circulation of the so called "temperate VZV genotypes" in tropical regions and, to certain degree, overlooks the predominance of such lineages in certain non-temperate areas. Here, we further discuss and present new information about the overwhelming dominance of temperate VZV genotypes in Mexico regardless of geographical location and climate.SummaryUV radiation does not satisfactorily explain the distribution of VZV genotypes in different tropical and temperate regions of Mexico. Additionally, the cyclic behavior of varicella does not shown significant differences between regions with different climates in the country. More studies should be conducted to identify the factors directly involved in viral spreading. A better understanding of the modes of transmissions exploited by VZV and their effect on viral fitness is likely to facilitate the implementation of preventive measures for disease control.

Arctic parasitology: why should we care?

The significant impact on human and animal health from parasitic infections in tropical regions is well known, but parasites of medical and veterinary importance are also found in the Arctic. Subsistence hunting and inadequate food inspection can expose people of the Arctic to foodborne parasites. Parasitic infections can influence the health of wildlife populations and thereby food security. The low ecological diversity that characterizes the Arctic imparts vulnerability. In addition, parasitic invasions and altered transmission of endemic parasites are evident and anticipated to continue under current climate changes, manifesting as pathogen range expansion, host switching, and/or disease emergence or reduction. However, Arctic ecosystems can provide useful models for understanding climate-induced shifts in host-parasite ecology in other regions.