Malaria, caused by the protozoan parasites of the genus Plasmodium, is a major health problem in many countries of the world. Five parasite species namely, Plasmodium falciparum, P. vivax, P. malariae, P. ovale, and P. knowlesi, cause malaria in humans. Of these, P. falciparum and P. vivax are the most prevalent and account for the majority of the global malaria cases. In most areas of Africa, P. vivax infection is essentially absent because of the inherited lack of Duffy antigen receptor for chemokines on the surface of red blood cells that is involved in the parasite invasion of erythrocytes. Therefore, in Africa, most malaria infections are by P. falciparum and the highest burden of P. vivax infection is in Southeast Asia and South America. Plasmodium falciparum is the most virulent and as such, it is responsible for the majority of malarial mortality, particularly in Africa. Although, P. vivax infection has long been considered to be benign, recent studies have reported life-threatening consequences, including acute respiratory distress syndrome, cerebral malaria, multi-organ failure, dyserythropoiesis and anaemia. Despite exhibiting low parasite biomass in infected people due to parasite’s specificity to infect only reticulocytes, P. vivax infection triggers higher inflammatory responses and exacerbated clinical symptoms than P. falciparum, such as fever and chills. Another characteristic feature of P. vivax infection, compared to P. falciparum infection, is persistence of the parasite as dormant liver-stage hypnozoites, causing recurrent episodes of malaria. This review article summarizes the published information on P. vivax epidemiology, drug resistance and pathophysiology.

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Even though malaria is preventable and curable, it has become a serious threat to mankind. In 2016, there were an estimated 216 million cases of malaria across the world. The biology of its causative agent, i.e. Plasmodium parasite is full of complex mechanisms. There are five Plasmodium species responsible for malaria in humans, viz. Plasmodium falciparum, P. vivax, P. malariae, P. ovale and recently identified P. knowlesi that normally infect apes. In humans, malaria is spread by the injection of Plasmodium sporozoites through the bite of infectious Anopheles’ female mosquito during their blood meal. From the time of entry into human skin till the development into the asexual forms, the parasite undergoes several transformations. This review attempts to understand the science behind the pre-erythrocytic liver stage of Plasmodium. Research articles explaining parasite biology, cell-traversal, transformation stages, cell-egress process, etc. were retrieved from PubMed and google scholar database. Various known and unknown mechanisms and strategies used by the malaria parasite P. berghei in rodent models have been discussed in this review. Limited or no information was available for humans, due to technical feasibility and complexity of parasite’s life cycle. Hence, it was concluded that there is an urgent need to investigate the hepatic invasion, traversal and egress mechanism of P. falciparum and P. vivax for developing novel therapeutics to fight against malaria.

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Background & objectives: Mosquitoes are responsible for transmitting several diseases, including malaria, dengue, chikungunya, filariasis, and yellow fever, etc. Release of larvivorous fishes is one of the cheapest method of vector management approach, with long suppression of mosquito population. The present study identifies the native larvivorous fishes and evaluates their potential larvivoracity for biological control of mosquito larvae in an endemic malarious region. Methods: During the year 2012–13, an ecological descriptive study was carried out in diverse aquatic habitats of fish species found in different areas of Ranchi district, in Jharkhand state of India. Fishes were captured using fishing nets, and identified and classified according to the available keys. Their larvivorous potential was graded according to their feeding potential. Data on current conservation status as well as their abundance were also recorded and analysed. Results: In total, 30 larvivorous fish species belonging to seven orders, 10 families and 21 genera were identified. Order Cypriniformes and the family Cyprinidae were the most ascendant group constituting 66.7 and 60%, respectively. The grading assessment of larvivorous potential for different fish species revealed that, Colisa fasciatus possess maximum larvivoracity (+ + + + +). According to the conservation, assessment and management plan (CAMP, 1998), 60% species were at lower risk near threat (LRnt), while 86.7% species were at least concerned (LC) as per the IUCN, 2017 categorisation. All fish species preferred to inhabit in freshwater. Maximum species occurrence was found in the river (63.3%). Only 30% species were bottom feeders (BF). Interpretation & conclusion: The larvivoracity and habitat distribution analysis indicated that C. fasciatus, Oreochromis mossambica, Esomus danricus, Oryzias melastigma, Puntius sophore, P. ticto, Rasbora daniconius, R. elegans, Aplocheilus panchax, and Danio (B) rerio possess high-level larvivorous potentiality in nature and are recommended for malaria control in the study area. There is an increasing pressure on the fish fauna, of facing several threats, such as fishing, human interference, loss of habitat, overexploitation, pollution, siltation, trade, and diseases. Therefore, periodic survey and monitoring of fish biodiversity, demarcation of breeding sites, field level research study on the efficacy of these fishes, and public awareness on establishment of larvivorous fish ponds should be adopted as a part of the vector management approach in the endemic malarious region of Ranchi district in Jharkhand, India.

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Background & objectives: Aedes aegypti and Ae. albopictus are major arboviral vectors that are considered to lay eggs, and undergo preimaginal development only in fresh water collections. However, recently they have been also shown to develop in coastal brackish water habitats. The ability of the biologically variant salinity-tolerant Aedes vectors to transmit arboviral diseases is unknown. We therefore, investigated the infection of salinity-tolerant Aedes mosquitoes with dengue virus (DENV) and analysed dengue incidence and rainfall data to assess the contribution of salinity-tolerant Aedes vectors to dengue transmission in the coastal Jaffna peninsula in Sri Lanka. Methods: Brackish and fresh water developing female Ae. aegypti and Ae. albopictus were tested for their ability to become infected with DENV through in vitro blood feeding and then transmit DENV vertically to their progeny. An immunochromatographic test for the NS1 antigen was used to detect DENV. Temporal variation in dengue incidence in relation to rainfall was analysed for the peninsula and other parts of Sri Lanka. Results: Aedes aegypti and Ae. albopictus developing in brackish water, became infected with DENV through in vitro blood feeding and the infected mosquitoes were able to vertically transmit DENV to their progeny. Monsoonal rainfall was the discernible factor responsible for the seasonal increase in dengue incidence in the peninsula and elsewhere in Sri Lanka. Interpretation & conclusion: Fresh water Aedes vectors are main contributors to the increased dengue incidence that typically follows monsoons in the Jaffna peninsula and elsewhere in Sri Lanka. It is possible however, that brackish water-developing Aedes constitute a perennial reservoir for DENV to maintain a basal level of dengue transmission in coastal areas of the peninsula during the dry season, and this supports increased transmission when monsoonal rains expand populations of fresh water Aedes.

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Background & objectives: Scrub typhus is as an emerging infectious disease that generally causes acute febrile illness, with disease spectrum ranging from mild illness to multiorgan dysfunction. This study was aimed to report the clinical profile, complications and risk factors associated with severe illness in patients with scrub typhus, outside the intensive care setting. Methods: It was a prospective study, which involved recruitment of patients with acute febrile illness and diagnosed to have scrub typhus, who were admitted to the general medical wards of a tertiary care centre in Kanchipuram district, in semi-urban south India, over a 12 month period between June 2015 and May 2016. The diagnosis was established both clinically (with or without pathognomonic eschar) and by a positive test of IgM antibodies against scrub typhus by ELISA. The severity of scrub typhus was determined by the presence of organ dysfunction, and the factors associated with it were analyzed. Results: A total of 50 patients with mean age of 39.6±20.5 yr (mean ± SD) were admitted. The mean duration of illness before presentation was 9.10 ± 8.6 days. The mean duration of hospital stay was 7.7±3.6 days. The symptoms included fever, abdominal symptoms, headache, dysuria, breathlessness and altered sensorium. Most common findings on physical examination were eschar (58%), crepitations in the chest (36%), hepatomegaly (34%) and lymphadenopathy (30%). Thirty two percent had respiratory complications, 4% required mechanical ventilation, 24% had shock, 16% had acute kidney injury, and 6% had dysfunction of ≥2 organs. Age of >50 yr, longer duration of illness (>7 days), residence in a rural area and the absence of eschar were found to be independent risk factors for development of severe illness. Interpretation & conclusion: Severe scrub typhus infection among non-ICU patients is more likely to occur in elderly patients and in those with longer duration of illness prior to presentation. The subset of patients without eschar might be more prone to develop complications.

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Background & objectives: Leishmania parasites are sensitive to very low temperature. Cryotherapy is considered as an alternative to the existing pentavalent antimonials, for local treatment of cutaneous leishmaniasis (CL). Normally, liquid nitrogen (N₂) at a temperature of -196 °C, is used in cryotherapy of CL, but it’s efficacy is not consistent. Recently, few studies have also reported the use of carbon dioxide (CO₂) slush at -78.5 °C in CL cryotherapy. This study was aimed to evaluate the effectiveness of N₂ vs CO₂ cryotherapy for CL treatment in mice. Methods: In total, 21 BALB/c mice were infected with Leishmania major strain [MRHO/IR/74/ER]. Samples were divided into three groups based on the intervention provided—Solid CO₂ cryotherapy, liquid N₂ cryotherapy and control group; with seven mice randomly assigned to each group. Control group received no intervention, and in the other two groups cryotherapy was used every two weeks for maximum of three months. Follow up examinations were scheduled at the time of cryotherapy, during which the size of each lesion was measured. For three mice in each study group, the spleen parasite DNA load was quantified using real-time PCR. Results: After treatment, the liquid N₂ cryotherapy showed significant reduction in size of the lesions (p = 0.029) as compared to the solid CO₂ cryotherapy and control group. Also, Leishmania DNA load in spleen was significantly lower in the mice receiving liquid N₂ cryotherapy (p <0.001). Interpretation & conclusion: Liquid N₂ cryotherapy is superior to CO₂ cryotherapy, and it can be an effective method for controlling L. major infection. Further investigations are essential to find optimal number of treatment sessions and time intervals.

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Background & objectives: India is a signatory to the 1997 World Health Assembly resolutions on lymphatic fila- riasis, and other neglected tropical diseases, and supports global elimination of lymphatic filariasis by 2020. The global programme to eliminate lymphatic filariasis (GPELF) has two main components, viz. interrupting transmission of LF through mass drug administration; and managing morbidity and preventing disability. Consorted efforts by the Public Health Department in Tamil Nadu state (India) for elimination of LF was launched in the year 1997 concentrating on both the components of the programme. The data on the prevalence of filarial morbidity and its entire management at present is based on manual reports and registers maintained by the field functionaries. To overcome the constraints in the manual reporting, an attempt was made to develop a web-based reporting system with different modules and user-friendly interface. Methods: The Vellore and Thiruvannamalai districts were selected as a study area. The study was conducted between 2011 and 2014, which revealed that the entire morbidity management was based on the manual formats. Constraints in the present manual reporting were analysed. PHP and MySQL tools were used to generate user friendly modules. Feedback was collected from field functionaries at different health centre levels, on the adequacy in the modules and effectiveness of the web-based reporting system. Results: The online reporting modules facilitated data entry at the health subcentre level itself. Analysis and retrieval of data was facilitated at all other levels in the public health system. The modules also covered details of surgical interventions, ex-gratia payments and other benefits extended to the lymphoedema patients by the Government. Interpretation & conclusion: The usage and feedback of the web-based reporting system appeared very encouraging and reliable, indicating that it can be implemented in health programmes for disease management. This web-based user-friendly online reporting system can contribute largely to achieve the goals of the GPELF; specially after MDA is withdrawn.

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Background & objectives: Ilam province is one of the oldest known endemic foci of zoonotic cutaneous leishmani- asis (CL) in Iran; and the recent studies have shown an increasing trend in the number of cases from the region. This study was aimed to investigate the parasite species and genetic diversity of isolates obtained from CL patients based on the N-acetylglucosamine-1-phosphate transferase (nagt) gene. Methods: Exudate materials were collected from the swollen margin of the skin lesions of the patients suspected with CL who were referred to health centers laboratory of Mehran, Dehloran, Ilam and Malekshahi cities in the Ilam province. Demographic data were collected through a questionnaire. Smears were stained and examined microscopically. In total, 62 parasitologically positive samples were subjected to PCR-RFLP of nagt gene for identification of Leishmania species, in addition to genetic diversity investigation. Results: Nearly, half of the positive cases were referred from Mehran followed by Dehloran City (40.4%). These included people from different age groups (1 to 73 yr), with majority being male (66.1%). The common site of lesions was hand (48.4%). Half of the patients had multiple lesions; most of them were wet ulcerative type. A 1450-60 bp band of the nagt gene was amplified from all the samples. Digestion patterns of acetyl-coenzyme A carboxylase 1 (ACC1) enzyme were similar to what expected for Leishmania major. No difference was observed at the nucleotide acid level or resulting amino acid in nine sequenced samples on the basis of phylogenetic analyses. However, intra- species differences (0.0015) were observed amongst the L. major isolates of present study and the other parts of Iran. Interpretation & conclusion: The findings of this study demonstrated that the main causative agent of CL in Ilam Province is L. major, and there is no considerable heterogeneity among the L. major isolates. Moreover, nagt gene proved to be an efficient marker for differentiating Leishmania species. Further studies with more samples need to be carried out to achieve a more comprehensive result on the genetic variation of L. major isolates.

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Background & objectives: The pathological hallmark of scrub typhus infection is focal or disseminated vasculitis. As with other infections, antinuclear antibodies (ANA) have been previously described in scrub typhus. However, the underlying mechanisms and implications of this immunological phenomenon is not well understood. In the present work it was assessed whether ANA is associated with illness severity and outcomes. Methods: In this prospective study spanning one year, patients fulfilling the diagnostic criteria for scrub typhus were recruited. Patients with other acute infective febrile illnesses were taken as controls. ANA positivity was compared between the cases and controls. ANA in scrub typhus was assessed for correlation with disease severity, organ dysfunction and outcomes. Results: The cohort comprised of 149 patients (scrub 89; controls 60) with mean age 46.5 (SD=16.9) yr; 48.3% were female. ANA was detected in 48 (53.9%) patients with scrub typhus and 9(15%) controls (p < 0.001). The ANA pattern was predominantly speckled (93.8%) in both scrub typhus patients and controls. In patients with scrub typhus, ANA positivity was associated with increasing APACHE-III score [Odds ratio (OR) 1.01; 95% CI 0.99–1.03; p = 0.09]. On bivariate analysis, ANA tended to be correlated with acute respiratory distress syndrome (OR 2.32; 95% CI 0.98–5.46; p = 0.06), hepatic dysfunction (OR 2.25; 95% CI 0.94–5.39, p = 0.06) and aseptic meningitis (OR 6.83; 95% CI 0.80–58.05, p = 0.08). The presence of these antibodies did not correlate with duration of hospitalization or mortality. Convalescent sera on 31 ANA positive scrub typhus patients demonstrated persistence of ANA in only 5 (16.1%) patients. Interpretation & conclusion: The disappearance of ANA during the convalescent phase suggests that ANA is expressed during the acute phase of scrub typhus infection. Its association with organ dysfunction warrants further study of the mechanisms and impact of autoantibody formation in scrub typhus.

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