SM Tropical Medicine Journal

Archive Articles

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Parasitism by Tylenchid Nematodes in Natural Populations of Pintomyia f ischeri (Diptera: Psychodidae: Phlebotominae) in Argentina

Pintomyia fischeri adults collected in different eco-epidemiological studies in the northeastern of Argentina were found parasitized by juvenile nematodes (Tylenchida) isolated from the body cavity. The percentage of infected females and males was 3.8% and 2.9% respectively. Part of the life cycle of sand flies and tylenchid nematodes take place in humid and dark sites, where infection of immature stage of Phlebotominae insects is possible. Biology of this parasite could help to determine the breeding sites of sand flies. This study constituted the first report of tylenchid nematodes infecting sand flies at field conditions in South-America.

Fernández MS¹,², Santini MS²,³, Diaz JI²,⁴, Villarquide L⁵, Lestani E¹, Salomón OD¹,², and Achinelly M²,⁴*


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Biochemical Changes in the Rumen Infecting Paramphistome, Gastrothylax crumenifer during Miracidial and Intramolluscan Developmental Stages

We hypothesize that the level of various biomolecules is variable and remain in a dynamic state during the course of development in Gastrothylax crumenifer. The aim of the present study is to determine whether these molecules are in dynamic state or their levels are constant in all the developmental stages. The present study was designed to investigate level of various macromolecules e.g. protein, glycogen, lipid, lipid fractions and nucleic acids by standard Spectrophotometric methods. All the biomacromolecules are expressed in terms of mg/g wet weight. A minimum of three separate replicates were run for each experiment. To investigate similarities/ differences in polypeptides of different developmental stages namely fresh eggs, eggs containing mature miracidia (Em), cercariae, metacercariae, immature and adult stages, SDS-gradient PAGE was performed. In the present study we have investigated biochemical alterations during the larval stages of Gastrothylax crumenifer (a rumen infecting paramphistome) which revealed marked differences during the miracidial development as well as in the intra-molluscan larval stages. We observed that the protein, glycogen and lipid of freshly laid eggs were utilized during the development. Concentration of protein, glycogen and lipid contents significantly elevated in the cercariae as compared to the non-feeding metacercarial stage, indicating an adaptation of the parasite to build up the nutrients for the metacercariae which is a dormant stage. Very little amount of lipid was detected in the fresh eggs (E0) which further decreased in the eggs containing mature miracidia (Em) and then increased sharply in the cercarial and metacercarial stages indicating the substantial buildup of lipid reserves. Nucleic acid contents decreased from E0 to the subsequent developmental stages. Such changes could be of intrinsic significance for the cellular differentiation and organogenesis in larval paramphistomes. Further, we analyzed polypeptide profile of developmental stages which revealed heterogeneous mixture of polypeptides. A total of 27, 15, 14, 15, 14 and 34 polypeptides in E0, Em, cercariae, metacercariae, immature and adult G. crumenifer, respectively were resolved. Eight and nine characteristic polypeptides (17-90 kDa) were observed in E0 and adult stages respectively.

Mohammad Khalid Saifullah¹, Gul Ahmad², Syed Mohammad Abbas Abidi¹, and Sabiha Khatoon¹*


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Molecular Profiling and Characterization of Integrons and Genotyping of Escherichia coli and Klebsiella pneumoniae Isolates Obtained from North Indian Tertiary Care Hospital

While the emergence of antibacterial drug resistance is a great emerging health issue that threatens the clinical usefulness of these drugs, it is important to study the spread of antibiotic resistance genes in order to understand the relationship between resistance gene pool and its mobilization through transposons and integrons. 125 cefoxitin-resistant E. coli (109) and K. pneumoniae (16) isolates were looked for the presence of integrons in order to illustrate the location of antibiotic resistance genes (especially blaampC ). The genotyping was done by RAPD so as to find out genetic relatedness among isolates. 55.20% (69/125) isolates were found positive for integrons. 41 isolates showed single amplification band for CS region, 20 showed two bands, 4 showed three bands and four isolates showed multiple banding patterns. Sul-1 was reported to be present in 3’CS, but we also observe 14/69 isolates that showed amplification for 5’CS-3’CS region but did not show presence of Sul-1 (when detected by PCR). Out of 109 E. coli isolates, 91 could be typed by RAPD, while 18 were found untypable. Among 91 E. coli isolates, 33 were grouped in 15 clusters while the remaining 58 isolates showed unique banding patterns indicating genetic un-relatedness. Among 16 K. pneumoniae isolates, 14 were typed by RAPD and 2 isolates were found untypable. The higher rate of resistance to several classes of β-lactam antibiotics in integron-positive isolates is probably attributable to the association of β-lactamase genes with integron-carrying plasmids and hence suggests that antibiotic drug resistance is transmitting through these mobilizing agents. As evident from RAPD-typing, most patients in our hospital were infected with different clades of organisms, thereby demonstrating clonal diversity among isolates suggesting horizontal transmission of bla genes

arrukh Sobia¹,², M Shahid¹,³, Sana Jamali¹,⁴, Haris M Khan¹, and Shahazad Niwazi²*


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Estrogen Metabolites for the Diagnosis of Schistosomiasis Associated Urinary Bladder Cancer

In a recent issue of Cancer Letters Gouveia and colleagues [1] studied a series of 40 Angolan patients diagnosed with Urogenital Schistosomiasis (UGS).

Monica C Botelho¹,², Helena Alves¹, and Joachim Richter³


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Long Term Prospects for a Vaccine against Zika Virus Hold Promise but Imminent Expectation should be Tempered by Reality

The rapid rise in the number of reported clinical cases of Zika in South and Central America over the span of a few months in late 2015 and early 2016 presents a real risk of a global epidemic of this Aedes mosquito transmitted viral infection. This threat is exacerbated by the globalisation of the human population which promotes the movement of asymptomatic carriers between nations in the same or separate continents. Pregnant women are considered at highest risk since microcephaly in the developing foetus is strongly associated with, if not yet proven as caused by, Zika infection. The possibility of additional modes of virus transmission, vertical and sexual, if confirmed, suggests the life cycle of the virus to be very complex and thus limits the scope of predictive models, which in turn may impede control efforts. Currently, no anti-Zika vaccine is available and while this has now been prioritised by multiple funding agencies, it may take several years to come to commercial fruition. The fact that Zika is closely related to yellow fever and Japanese encephalitis viruses, for both of which effective vaccines exist, offers hope that the fast-tracked preparation of a candidate vaccine is feasible. However, performing clinical trials on pregnant women would provide ethical and practical challenges to overcome before licensure is granted for administration to the general public. In the meantime, alternative public health management strategies, such as vector control programs to target mosquito breeding, are required in order to limit the global spread of this re-emerging disease.

Andrew W Taylor-Robinson*


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Scrub Typhus Death: Losing the Precious Time

Introduction:

Scrub typhus is an acute febrile illness caused by the bacteria Orientia tsutsugamushi. Owing to the increase in the number of cases and a suspected death due to scrub typhus, the director of health services, Kerala state, requested a death audit and an outbreak investigation in the Nedumangad and Palode areas of Thiruvananthapuram district and the Department of Community Medicine, Medical College, Thiruvananthapuram was called in for technical expertise and this outbreak investigation was undertaken.

Methods:
The methodology involved a death audit for a suspected death due to scrub typhus, fever surveillance for detection of scrub typhus cases among admitted patients in two local hospitals, training need assessment using a rapid assessment questionnaire and house visit of three confirmed cases of scrub typhus in the recent past.

Results:
The death audited was likely due to Scrub typhus. Scrub typhus could have caused an acute kidney injury aided by rhabdomyolysis, or it could have precipitated an acute exacerbation of an already existing kidney disease resulting from the patients’ long-standing untreated diabetes mellitus. The presence of rats and shrubs in the area, the history of active involvement of the patient in the sanitation works of the area, the history and clinical finding of eschar in the patient along with two positive IgM Scrub typhus lab reports done in an interval of fifteen days, are strongly suggestive. Two out of the ten blood samples collected for the fever surveillance tested positive for scrub typhus IgM. Training need assessment revealed good knowledge among health care workers, but minimal experience of dealing with actual cases. The household visits identified potential environmental risk factors like abundance of shrub vegetation, rat infestations, involvement in activities like clearing of shrubs, and contact with pets.

Conclusion:
A strong suspicion is necessary for an early diagnosis of scrub typhus and scrub typhus co-infections. Delay in the initiation of treatment could be a potential reason for death due to scrub typhus. The absence of eschar should not be taken as a criterion for ruling out scrub typhus. The community should be empowered for early treatment seeking. Surveillance should be strengthened. Capacity building of health professionals may facilitate early case detection, treatment and prevention of deaths.

Devraj Ramakrishnan¹, Zinia T Nujum¹, Sara Varghese¹,², Umarul Farook³, Betty Christopher³, Swapna S Abraham⁴, and Mariette J Pious⁵*


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An Adenovirus Outbreak Associated with a Swimming Facility

Adenovirus outbreaks have been reported to be associated with recreational water over the past decades. An outbreak of respiratory tract infection in a primary school in central Taiwan occurred in September 2011. The laboratory tests showed that it was an outbreak of adenovirus infection. Epidemiological investigations revealed that the outbreak was associated with a swimming facility outside the school. Our report emphasized the potential threat of adenovirus infection associated with swimming facilities, especially in a community adenovirus epidemic setting.

Sung-Hsi Wei1,2* 


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Respiratory Syncytial Virus-like Particles Consisting of M, G and Prefusion F

Respiratory Syncytial Virus (RSV) infection is of public health concern worldwide. Globally, it is a common cause of bronchiolitis and pneumonia in childhood, outbreaks occurs every year depending on the locale. Worldwide, it is estimated that 30 million Lower Respiratory Tract Infections (LRI), 3 million hospitalization and 160,000 deaths occur annually. It also causes morbidity/mortality in the elderly/at risk adults. In spite of concentrated efforts of many over more than five decades, vaccine or therapy for this virus has remained elusive. Many conventional and newer vaccine strategies have been evaluated but none have been licensed to date. We are exploring mammalian cell-derived Virus-like Particles (VLPs) composed of the two surface glycoproteins G and prefusion F (RSV fVLPs) and M as vaccine. In prefusion F there is a neutralizing epitope at site zero that induces significantly higher Neutralizing Antibody (NtAb) titers. In preliminary studies, we have shown by Electron Microscopy (EM) that our fVLPs are functional and immunoreactive. We have done western blot with two conformation dependent antibodies AM14, and D25, and Motavizumab which is conformation independent. We have shown also that MPLA-adjuvanted fVLPs induced 8.2Log2±1.13 NtAb titers. With regular F (instead of prefusion F) lower NtAb titers are seen in cotton rats and in mice. On challenge lung virus titers in the homogenate was almost clear.

Pramila Walpita1* and Lisa M Johns1 


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Incorporating Public Awareness into Climate Change Health Planning

Climate change is a global issue and its immediate and long-term health effects are significant and severe. According to the World Health Organization (WHO, 2016), “Between 2030 and 2050, climate change is expected to cause approximately 250,000 additional deaths per year, from malnutrition, malaria, diarrhea and heat stress”.

Carmit Rapaport¹ and Isaac Ashkenazi¹*


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Major Resistant Mechanism to Insecticides of Aedes aegypti Mosquito: a Vector of Dengue and Zika Virus in Vietnam

Aedes aegypti, a main vector of dengue fever, is very high density in some areas of Vietnam. These mosquitoes in some cities such as Hanoi (HN), Nhatrang (NT), Dongnai (DN), Kiengiang (KG), Daklak (DL), and Hochiminh (HCM) cities have been found high resistance to Pyrethroid group and DDT. Mosquito populations have been sensitive to malathion insecticide.

Identifying insecticide resistant characteristics by esterase enzyme electrophoresis showed that the first esterase appeared in pyrethroid insecticide resistant mosquito population and not recorded in Bora Bora strain.

Analysis of mutations in by multiplex PCR 1011 and 1016 codons encoding VAL and ISO in 20 and 21 exons showed that mutation in 1016 codons with two types VAL/1016/ISO and VAL/1016/GLY were found in the domain II of the sodium channel gene with 94 Aedes aegypti adult female mosquitoes after susceptibility test to alphacypermethrin. The results showed that no mutation in 1011 codon encoding ISO was observed. 14 samples collected from four provinces containing mutations in 1016 codons with two VAL/1016/ISO and VAL/1016/GLY types have been detected.

Khoa Pham Thi¹, Hieu Ho Viet¹ and Hung Minh Nguyen¹*