Journal of Vector Borne Diseases 2018 55(3):173-183
Visceral leishmaniasis (VL) is an important parasitic disease which is endemic in different parts of Iran; and domestic and wild canines are principal reservoir hosts of the disease. The objective of this study was to review the spatial distribution of canine VL (CVL) caused by Leishmania infantum in domestic and wild canines in different geographical areas of Iran. An extensive literature search was conducted in different international and national databases, including Cochrane, MEDLINE/PubMed, Scopus, Web of Science and Iran Medex to find articles with the words “visceral leishmaniasis in Iran” in their titles and “canine visceral leishmaniasis in Iran” or “feline visceral leishmaniasis in Iran” or “accidental reservoir hosts of visceral leishmaniasis in Iran” in their subtitles, irrespective of the type and duration of study. Screening of the irrelevant articles from total 36,342, yielded 61 eligible articles. More than 93% of the studies were carried out on domestic dogs (Canis familiaris, n = 57) and the remaining were on other carnivores such as wild canines including foxes (Vulpes vulpes, n = 4), jackals (C. aureus, n = 6) and wolves (C. lupus, n = 6); while studies on domestic cats (Felis catus, n = 3) as well as desert rodents (n = 2) were rare. The average rate of L. infantum infections reported among domestic dogs using direct agglutination test (DAT) in Iran was 12.5%. The highest prevalence rate (14%) was reported from the northwest regions of the country where VL is endemic. The review indicates that CVL is endemic in various parts of Iran and domestic dogs are the main and potential reservoir hosts of the disease. Other carnivores, such as domestic cats and some species of desert rodents (Cricetulus migratorius, Mesocricetus auratus and Meriones persicus) seem to be playing a role in the maintenance of transmission cycle of L. infantum in the endemic areas of the disease.
Journal of Vector Borne Diseases 2018 55(3):184-188
Background & objectives: Insecticide applied at optimum dosage and coverage delays the development of resistance in disease vectors. The study was aimed to test the hypothesis whether decrease in exposure to insecticide leads to decrease in selection of insecticide resistance in mosquitoes. The mosquitoes were variably exposed to insecticide in the laboratory by simulating the variations in insecticide sprays applied in the field. Methods: The study was carried out on DDT resistant adults of Anopheles stephensi. Mosquitoes were differentially exposed to impregnated papers of DDT (4%), that were differentially masked to 25, 50, and 75% area with an unimpregnated Whatman No.1 filter paper, and to a positive control without any masking, i.e. 100% exposure area. The study was conducted for five generations and at each generation mosquitoes were exposed to differentially masked impregnated papers, and percent mortality was calculated. Results: The observed survival rate in differential exposures was more with the increase in heterozygous genotype resistance-susuceptible (RS) frequency. Resistant gene frequency with differential exposures (25 to 75%) was in the range of 0.38–0.54 for the F0 generation, which increased to 0.84–0.93 for the F4 generation. In 100% exposure it was 0.18 in F0 generation, which increased to 0.58 in the F4 generation. The resistant gene frequencies in the population showed increasing trend with decrease in exposure in contrast to complete exposure. Interpretation & conclusion: Variable simulated exposures resulted in precipitation of increased resistance while complete exposure resulted in lower levels of resistance, signifying the importance of optimum dosage and coverage in the indoor residual spray in delaying/avoiding the development of insecticide resistance in the disease vectors.
Journal of Vector Borne Diseases 2018 55(3):189-196
Background & objectives: Increase of vector-borne diseases (VBDs) in India has posed a question on the situation in Lakshadweep Islands, where VBDs are reported from time-to-time. The present investigation was aimed to assess the faunastic situation of the prevailing vectors along with their breeding sites in different islands of the Lakshadweep. Methods: Extensive surveys were carried out from November 2017 to January 2018 (post-monsoon season) randomly in the nine inhabited islands of Lakshadweep for conducting faunastic studies on mosquitoes and to know the basic binomics like breeding and resting preference of mosquitoes. The study islands included, Kavaratti, Agatti, Chetlat, Bitra, Amini, Kadmath, Andrott, Kalpeni and Kiltan. Both immature and adult collections were carried out by standard/appropriate sampling techniques. The obtained data were calculated and analysed in terms of different entomological indices Results: A total of 3356 mosquitoes were collected during the study period which comprised of 16 species from nine genera. Out of the 16 species, six belonged to mosquito vectors. The collection included malaria vector, Anopheles stephensi; Japanese encephalitis vector, Culex tritaeniorhynchus; Bancroftian filariasis vector, Cx. quinquefasciatus; Brugian filariasis vector, Mansonia uniformis; and dengue and chikungunya vectors, Stegomya albopicta and St. aegypti. Stegomya albopicta was the most predominant species observed constituting 54% of the catch, followed by Cx. quinquefasciatus, An. stephensi, Cx. tritaeniorhynchus, and St. aegypti constituting 10.5, 6, 3 and 1.2%, respectively. Apart from vector species many non-vectors such as Heizmannia chandi, An. subpictus, An. varuna, Cx. sitiens, Cx. minutissimus, Cx. rubithoracis, Fredwardsius vittatus, Lutzia fuscana, Malaya genurostris and Armigeres subalbatus were also present in the study area. In Kavaratti Island, the capital of Lakshadweep, a non-vector species of sandfly, Sergentomyia (Parrotomyia) babu was observed during the indoor resting collection. The major breeding sites which supported various mosquito species included, discarded plastic containers, tree holes, open sintex tanks (water storage tanks), unused wells, discarded tyres, discarded iron pots, unused and damaged boats, cement tanks, pleated plastic sheets, coral holes, pits and irrigation canals, discarded washing machines, and Colocasia plant leaf axils. Breteau index ranged between 65.3 and 110, CI ranged between 63.64 and 72.41; and HI ranged between 38.46 and 70 among the various islands. Interpretation & conclusion: Entomological indices such as house index (HI), breteau index (BI) and pupal index (PI) were high in all the nine islands and exceeded the threshold levels specified by WHO, indicating high risk for dengue virus transmission in case of outbreaks. Occurrence of vector as well as non-vector species indicates that the global change in climate is causing notable changes in terms of breeding of vector and non-vector species in the islands. With the reported cases of VBDs and the presence of vectors species in Lakshadweep Islands, a stringent control measure needs to be implemented at the Lakshadweep Islands.
Journal of Vector Borne Diseases 2018 55(3):197-202
Background & objectives: Three doses of intermittent preventive treatment with sulphadoxine-pyrimethamine (IPTp-SP) has been adopted as the new recommendation for prevention of malaria in pregnancy. This study evaluated the effectiveness of two-dose versus three-dose of SP for IPTp-SP in the prevention of low birth weight (LBW) and malaria parasitaemia. Methods: An open, randomized, controlled, longitudinal trial was conducted in a secondary level hospital in Nsukka region of Enugu State, Nigeria. A sample of 210 pregnant women within gestational ages of 16–24 wk were recruited at antenatal clinics and equally randomized to either a two-dose SP or three-dose SP group. The primary endpoints were LBWs, peripheral, and placental parasitaemia, while the secondary endpoints were maternal anaemia, pre-term birth, clinical malaria and adverse effects of SP. Results: Among 207 cases followed till delivery, the prevalence of parasitaemia was lower in three-dose group than in two-dose group for both peripheral (9.3% versus 27.8%) and placental (10.6% versus 25.6%) parasitaemia. The adjusted odds ratios (aOR) were 0.15 [95% confidence interval (CI), 0.05 – 0.45] and 0.17 (95% CI, 0.06–0.51), respectively. The prevalence of LBW was also lower in three-dose (3.5%) than in two-dose (12.2%) group (aOR, 0.15; 95% CI, 0.04–0.63); however, the prevalence of maternal anaemia, pre-term births, clinical malaria and SP adverse effects were similar between the two arms of treatment. Interpretation & conclusion: Addition of a third SP dose to the standard two-dose SP for IPTp led to improved reductions in the risk of some adverse pregnancy outcomes.
Journal of Vector Borne Diseases 2018 55(3):203-207
Background & objectives: Japanese encephalitis (JE) is a mosquito-borne zoonotic disease. The JE virus (JEV) does not cause any disease among its natural hosts and transmission continues through mosquitoes belonging to Culex vishnui subgroup. This study was aimed to investigate the prevalence of JEV in mosquitoes and humans in the Thanjavur district, a non-endemic region for JE, in Tamil Nadu, by using standard available assays. Methods : A sero-surveillance study was conducted in Thanjavur district among the normal rural school children in the 5–12 yr age group, during the JE season (October) and post-JE season (February) from 2011 to 2013 for the detection of JEV infection. Vector abundance studies were carried out from 2011 to 2014. JE seropositivity and its association between the seasons were analysed statistically. Results : The occurrence of JE infection among children aged 5–12 yr was very high in the study area. The infection rates for JE in two consecutive seasons for 2011–12 and 2012–13 were 32.2 and 65.2%, respectively. The Cx. tritaeniorhynchus sp. dominated the catch, and was majorly responsible for the transmission. There was a significant difference in the human infection rate compared to the years 1991–92 and 1992–93; and a marked decrease in the cattle to pigs ratio (123 : 1) compared to the studies in 1991–93. Interpretation & conclusion : The study unearthed the prevailing situation of JE among children, who are at higher risk of developing the disease during the transmission season. The decrease in the cattle to pigs ratio might be the one of the reasons for increase in the JEV infection among the children population compared to 20 years before. This trend requires urgent attention as it could be prevented with effective surveillance systems and vaccines.
Journal of Vector Borne Diseases 2018 55(3):208-214
Background & objectives : Schistosomiasis is a rural endemic disease that has been expanding to urban and coastal areas in the state of Pernambuco, Brazil. The aim of this study was to characterize the distribution of breeding sites of the causative vector, Biomphalaria straminea in an endemic municipality for schistosomiasis and to present the predictive models for occurrences and dispersal of this vector snail to new areas. Methods : A malacological survey was conducted during January to December 2015 in the municipality of São Lourenço da Mata, Pernambuco, Brazil to identify the breeding sites of Biomphalaria. Faecal contamination was determined by means of the Colitag™ diagnostic kit. Rainfall data were collected, and correlated with snail distribution data. Kernel density estimation, kriging and maximum entropy (MaxEnt) modeling were used for spatial data analysis, by means of the spatial analysis software packages. Results : Out of the 130 demarcated collection points, 64 were classified as breeding sites for B. straminea. A total of 5,250 snails were collected from these sites. Among these 64 sites, four were considered as foci of schistosomiasis transmission and 54 as potential transmission foci. An inverse relationship between rainfall and snail density was observed. Kernel spatial analysis identified three areas at higher risk of snail occurrence, which were also the areas of highest faecal contamination and included two transmission foci. Kriging and MaxEnt modeling simulated the scenarios obtained through the kernel analyses. Interpretation & conclusion : Use of geostatistical tools (Kriging and MaxEnt) is efficient for identifying areas at risk and for estimating the dispersal of Biomphalaria species across the study area. Occurrence of B. straminea in the study area is influenced by the rainy season, as it becomes more abundant during the period immediately after the rainy season, increasing the risk of dispersal and the appearance of new transmission foci.
Journal of Vector Borne Diseases 2018 55(3):215-221
Background & objectives : Crimean-Congo hemorrhagic fever (CCHF), an illness characterized by fever and hemorrhage, is caused by a CCHF virus (CCHFV). It is an important public health problem in Turkey. The objective of this study was to evaluate the demographic, clinical, and laboratory characteristics and mortality rates of CCHF patients in the northeast region of Turkey. Methods : A total of 206 patients, diagnosed with CCHF, from northeast region of Turkey were included and evaluated between 2011 and 2017. Real-time reverse transcriptase polymerase chain reaction (RT-PCR) and immunofluorescence (IFA) methods were used for the diagnoses. Results : Of the patients included in the study, 77.2% were farmers/livestockers, while 22.8% had other occupations. The incidence of tick bite or tick contact with bare hands was 52.9%. About 94.2% of the patients were living in rural areas and 5.8% in city centers. However, all the patients living in city centers had a history of visit to rural areas. The disease was more common in May, June, and July months. The most common symptoms at the time of admission included fatigue, fever, and widespread body pain, while laboratory findings were thrombocytopenia, leukopenia, and anemia. Bleeding, tachycardia, and rash were the most common findings on physical examination. Of all the patients, 95.6% were identified by RT-PCR and 4.4% by IFA methods. Severe cases constituted 22.3% (46) of the included patients. Throughout the course of this study, 7 (3.4%) patients died, and the remaining 96.6% (199) patients were discharged with a full recovery. Disease severity was significantly correlated with mortality rate and duration of hospitalization (p <0.001 and p = 0.013). Interpretation & conclusion : In this study, the mortality rate observed was lower than that reported in the literature because of accessibility of early supportive therapy. It would be beneficial in CCHF treatment to recognize the disease at an early stage, begin supportive treatment quickly, and educate the people living in high-risk areas as well as health care personnel working in these areas.
Journal of Vector Borne Diseases 2018 55(3):222-229
Background & objectives : The presence of Babesia spp in humans, bovine cattle and ticks (the transmitting vector) has not been well characterized in Colombia. Babesia infection in humans can be overlooked due to similarity of the disease symptoms with malaria specially in the regions where malaria is endemic. The aim of the present work was to study the frequency of Babesia infection in humans, bovines and ticks in a malaria endemic region of Colombia, and explore the possible relationship of infection with host and the environmental factors. Methods : A cross-sectional study was carried out between August 2014 and March 2015 to determine the frequency of B. bovis and B. bigemina infection in a sample of 300 humans involved in cattle raising, in 202 bovines; and in 515 ticks obtained from these subjects, using molecular (PCR), microscopic and serological methods. In addition, the demographic, ecological and zootechnical factors associated with the presence of Babesia, were explored. Results : In the bovine population, the prevalence of infection was 14.4% (29/202); the highest risk of infection was found in cattle under nine months of age (OR = 23.9, CI 8.10–94.30, p = 0.0). In humans, a prevalence of 2% (6/300) was found; four of these six cases were positive for B. bovis. Self-report of fever in the last seven days in the positive cases was found to be associated with Babesia infection (Incidence rate ratio = 9.08; CI 1.34–61.10, p = 0.02). The frequency of B. bigemina infection in the collected ticks was 18.5% (30/162). Interpretation & conclusion : The study established the presence of Babesia spp in humans, bovines and ticks. The most prevalent species responsible for babesiosis in humans and bovines was B. bovis, while B. bigemina was the species most frequently found in the tick population. The results contribute to the knowledge of the epidemiology of babesiosis in the country and can provide guidelines for the epidemiological surveillance of this non-malarial febrile illness in humans as well as cattle.
Journal of Vector Borne Diseases 2018 55(3):230-234
Background and objectives : The dogs are considered the main reservoir of visceral leishmaniasis (VL), but lately the disease incidence has been reported in cats also. In this study, the susceptibility of domestic cats to experimental Leishmania infantum infection was assessed by different diagnostic methods. Methods : A total of 12 healthy adult male cats were captured by double door live trap cages containing baits. Of them eight cats were intraperitoneally inoculated with 107 L. infantum promastigotes (stationary phase), and four cats were used as controls. Whole blood and serum samples were collected at weekly intervals for 16 wk after inoculation for testing by polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) methods. Aspirates of prescapular lymph nodes and bone marrow were obtained at monthly intervals. Clinical examination was performed twice weekly and histopathological evaluation was done on necropsy samples at the termination of the study. Results: One week after inoculation, blood nested PCR was able to detect the L. infantum infection and it remained positive until 16 wk. ELISA test remained negative during the study. Amastigote phase of parasite was not observed in bone marrow aspiration and necropsy samples. Interpretation and conclusion : The feline model described in this work would be useful in further understanding of L. infantum immunopathogenensis in cats. The results of this preliminary study suggest that cats might be resistant to VL as the inoculation dose which induces pathognomonic clinical features in dogs, just creates asymptomatic parasitaemia in cats. Though, due to long-lasting parasitaemia, cats may act as appropriate reservoir for transmission of VL to human population. Further studies are needed to describe the possible role of cats in the epidemiology of VL in endemic areas.
Journal of Vector Borne Diseases 2018 55(3):235-238
REVIEW ARTICLE
Geographic distribution and spatial analysis of Leishmania infantum infection in domestic and wild animal reservoir hosts of zoonotic visceral leishmaniasis in Iran: A systematic review
p. 173
M Mohebali, E Moradi-Asl, Y Rassi DOI:10.4103/0972-9062.249125
Visceral leishmaniasis (VL) is an important parasitic disease which is endemic in different parts of Iran; and domestic and wild canines are principal reservoir hosts of the disease. The objective of this study was to review the spatial distribution of canine VL (CVL) caused by Leishmania infantum in domestic and wild canines in different geographical areas of Iran. An extensive literature search was conducted in different international and national databases, including Cochrane, MEDLINE/PubMed, Scopus, Web of Science and Iran Medex to find articles with the words "visceral leishmaniasis in Iran" in their titles and "canine visceral leishmaniasis in Iran" or "feline visceral leishmaniasis in Iran" or "accidental reservoir hosts of visceral leishmaniasis in Iran" in their subtitles, irrespective of the type and duration of study. Screening of the irrelevant articles from total 36,342, yielded 61 eligible articles. More than 93% of the studies were carried out on domestic dogs (Canis familiaris, n= 57) and the remaining were on other carnivores such as wild canines including foxes (Vulpes vulpes, n = 4), jackals (C. aureus, n = 6) and wolves (C. lupus, n = 6); while studies on domestic cats (Felis catus, n = 3) as well as desert rodents (n = 2) were rare. The average rate of L. infantum infections reported among domestic dogs using direct agglutination test (DAT) in Iran was 12.5%. The highest prevalence rate (14%) was reported from the northwest regions of the country where VL is endemic. The review indicates that CVL is endemic in various parts of Iran and domestic dogs are the main and potential reservoir hosts of the disease. Other carnivores, such as domestic cats and some species of desert rodents (Cricetulus migratorius, Mesocricetus auratus and Meriones persicus) seem to be playing a role in the maintenance of transmission cycle of L. infantum in the endemic areas of the disease.
A laboratory simulation study on suppression of resistance genes by differential exposures to an insecticide in Anopheles stephensi Liston population
p. 184
Vaishali Verma, OP Agrawal, Poonam Sharma Velamuri, Kamaraju Raghavendra DOI:10.4103/0972-9062.249126
Background & objectives: Insecticide applied at optimum dosage and coverage delays the development of resistance in disease vectors. The study was aimed to test the hypothesis whether decrease in exposure to insecticide leads to decrease in selection of insecticide resistance in mosquitoes. The mosquitoes were variably exposed to insecticide in the laboratory by simulating the variations in insecticide sprays applied in the field.Methods: The study was carried out on DDT resistant adults of Anopheles stephensi. Mosquitoes were differentially exposed to impregnated papers of DDT (4%), that were differentially masked to 25, 50, and 75% area with an unimpregnated Whatman No.1 filter paper, and to a positive control without any masking, i.e. 100% exposure area. The study was conducted for five generations and at each generation mosquitoes were exposed to differentially masked impregnated papers, and percent mortality was calculated. Results: The observed survival rate in differential exposures was more with the increase in heterozygous genotype resistance-susuceptible (RS) frequency. Resistant gene frequency with differential exposures (25 to 75%) was in the range of 0.38–0.54 for the F0 generation, which increased to 0.84–0.93 for the F4 generation. In 100% exposure it was 0.18 in F0 generation, which increased to 0.58 in the F4 generation. The resistant gene frequencies in the population showed increasing trend with decrease in exposure in contrast to complete exposure. Interpretation & conclusion: Variable simulated exposures resulted in precipitation of increased resistance while complete exposure resulted in lower levels of resistance, signifying the importance of optimum dosage and coverage in the indoor residual spray in delaying/avoiding the development of insecticide resistance in the disease vectors.
Prevalence of disease vectors in Lakshadweep Islands during post-monsoon season
p. 189
Jayalakshmi Krishnan, L Mathiarasan DOI:10.4103/0972-9062.249127
Background & objectives: Increase of vector-borne diseases (VBDs) in India has posed a question on the situation in Lakshadweep Islands, where VBDs are reported from time-to-time. The present investigation was aimed to assess the faunastic situation of the prevailing vectors along with their breeding sites in different islands of the Lakshadweep. Methods: Extensive surveys were carried out from November 2017 to January 2018 (post-monsoon season) randomly in the nine inhabited islands of Lakshadweep for conducting faunastic studies on mosquitoes and to know the basic binomics like breeding and resting preference of mosquitoes. The study islands included, Kavaratti, Agatti, Chetlat, Bitra, Amini, Kadmath, Andrott, Kalpeni and Kiltan. Both immature and adult collections were carried out by standard/appropriate sampling techniques. The obtained data were calculated and analysed in terms of different entomological indices Results: A total of 3356 mosquitoes were collected during the study period which comprised of 16 species from nine genera. Out of the 16 species, six belonged to mosquito vectors. The collection included malaria vector, Anopheles stephensi; Japanese encephalitis vector, Culex tritaeniorhynchus; Bancroftian filariasis vector, Cx. quinquefasciatus; Brugian filariasis vector, Mansonia uniformis; and dengue and chikungunya vectors, Stegomya albopicta and St. aegypti. Stegomya albopicta was the most predominant species observed constituting 54% of the catch, followed by Cx. quinquefasciatus, An. stephensi, Cx. tritaeniorhynchus, and St. aegypti constituting 10.5, 6, 3 and 1.2%, respectively. Apart from vector species many non-vectors such as Heizmannia chandi, An. subpictus, An. varuna, Cx. sitiens, Cx. minutissimus, Cx. rubithoracis, Fredwardsius vittatus, Lutzia fuscana, Malaya genurostris and Armigeres subalbatus were also present in the study area. In Kavaratti Island, the capital of Lakshadweep, a non-vector species of sandfly, Sergentomyia (Parrotomyia) babu was observed during the indoor resting collection. The major breeding sites which supported various mosquito species included, discarded plastic containers, tree holes, open sintex tanks (water storage tanks), unused wells, discarded tyres, discarded iron pots, unused and damaged boats, cement tanks, pleated plastic sheets, coral holes, pits and irrigation canals, discarded washing machines, and Colocasia plant leaf axils. Breteau index ranged between 65.3 and 110, CI ranged between 63.64 and 72.41; and HI ranged between 38.46 and 70 among the various islands. Interpretation & conclusion: Entomological indices such as house index (HI), breteau index (BI) and pupal index (PI) were high in all the nine islands and exceeded the threshold levels specified by WHO, indicating high risk for dengue virus transmission in case of outbreaks. Occurrence of vector as well as non-vector species indicates that the global change in climate is causing notable changes in terms of breeding of vector and non-vector species in the islands. With the reported cases of VBDs and the presence of vectors species in Lakshadweep Islands, a stringent control measure needs to be implemented at the Lakshadweep Islands.
Comparison of the effectiveness of two-dose versus three-dose sulphadoxine-pyrimethamine in preventing adverse pregnancy outcomes in Nigeria
p. 197
Nneka U Igboeli, Maxwell O Adibe, Chinwe V Ukwe, Cletus N Aguwa DOI:10.4103/0972-9062.249128
Background & objectives: Three doses of intermittent preventive treatment with sulphadoxine-pyrimethamine (IPTp-SP) has been adopted as the new recommendation for prevention of malaria in pregnancy. This study evaluated the effectiveness of two-dose versus three-dose of SP for IPTp-SP in the prevention of low birth weight (LBW) and malaria parasitaemia. Methods: An open, randomized, controlled, longitudinal trial was conducted in a secondary level hospital in Nsukka region of Enugu State, Nigeria. A sample of 210 pregnant women within gestational ages of 16–24 wk were recruited at antenatal clinics and equally randomized to either a two-dose SP or three-dose SP group. The primary endpoints were LBWs, peripheral, and placental parasitaemia, while the secondary endpoints were maternal anaemia, pre-term birth, clinical malaria and adverse effects of SP. Results: Among 207 cases followed till delivery, the prevalence of parasitaemia was lower in three-dose group than in two-dose group for both peripheral (9.3% versus 27.8%) and placental (10.6% versus 25.6%) parasitaemia. The adjusted odds ratios (aOR) were 0.15 [95% confidence interval (CI), 0.05 – 0.45] and 0.17 (95% CI, 0.06–0.51), respectively. The prevalence of LBW was also lower in three-dose (3.5%) than in two-dose (12.2%) group (aOR, 0.15; 95% CI, 0.04–0.63); however, the prevalence of maternal anaemia, pre-term births, clinical malaria and SP adverse effects were similar between the two arms of treatment.Interpretation & conclusion: Addition of a third SP dose to the standard two-dose SP for IPTp led to improved reductions in the risk of some adverse pregnancy outcomes.
Changing paradigm in the epidemiology of Japanese encephalitis in a non-endemic region
p. 203
P Philip Samuel, V Thenmozhi, M Muniaraj, D Ramesh, S Victor Jerald Leo, T Balaji, K Venkatasubramani, J Nagaraj, R Paramasivan DOI:10.4103/0972-9062.249130
Background & objectives: Japanese encephalitis (JE) is a mosquito-borne zoonotic disease. The JE virus (JEV) does not cause any disease among its natural hosts and transmission continues through mosquitoes belonging to Culex vishnui subgroup. This study was aimed to investigate the prevalence of JEV in mosquitoes and humans in the Thanjavur district, a non-endemic region for JE, in Tamil Nadu, by using standard available assays. Methods : A sero-surveillance study was conducted in Thanjavur district among the normal rural school children in the 5–12 yr age group, during the JE season (October) and post-JE season (February) from 2011 to 2013 for the detection of JEV infection. Vector abundance studies were carried out from 2011 to 2014. JE seropositivity and its association between the seasons were analysed statistically. Results : The occurrence of JE infection among children aged 5–12 yr was very high in the study area. The infection rates for JE in two consecutive seasons for 2011–12 and 2012–13 were 32.2 and 65.2%, respectively. The Cx. tritaeniorhynchussp. dominated the catch, and was majorly responsible for the transmission. There was a significant difference in the human infection rate compared to the years 1991–92 and 1992–93; and a marked decrease in the cattle to pigs ratio (123 : 1) compared to the studies in 1991–93. Interpretation & conclusion : The study unearthed the prevailing situation of JE among children, who are at higher risk of developing the disease during the transmission season. The decrease in the cattle to pigs ratio might be the one of the reasons for increase in the JEV infection among the children population compared to 20 years before. This trend requires urgent attention as it could be prevented with effective surveillance systems and vaccines.
Spatial risk analysis on occurrences and dispersal of Biomphalaria straminea in and endemic area for schistosomiasis
p. 208
Elainne Christine de Souza Gomes, Millena Carla da Silva Mesquitta, Leandro Batista Wanderley, Fábio Lopes de Melo, Ricardo José de Paula Souza e Guimarães, Constança Simões Barbosa DOI:10.4103/0972-9062.249142
Background & objectives : Schistosomiasis is a rural endemic disease that has been expanding to urban and coastal areas in the state of Pernambuco, Brazil. The aim of this study was to characterize the distribution of breeding sites of the causative vector, Biomphalaria straminea in an endemic municipality for schistosomiasis and to present the predictive models for occurrences and dispersal of this vector snail to new areas. Methods :A malacological survey was conducted during January to December 2015 in the municipality of São Lourenço da Mata, Pernambuco, Brazil to identify the breeding sites of Biomphalaria. Faecal contamination was determined by means of the Colitag™ diagnostic kit. Rainfall data were collected, and correlated with snail distribution data. Kernel density estimation, kriging and maximum entropy (MaxEnt) modeling were used for spatial data analysis, by means of the spatial analysis software packages. Results : Out of the 130 demarcated collection points, 64 were classified as breeding sites for B. straminea. A total of 5,250 snails were collected from these sites. Among these 64 sites, four were considered as foci of schistosomiasis transmission and 54 as potential transmission foci. An inverse relationship between rainfall and snail density was observed. Kernel spatial analysis identified three areas at higher risk of snail occurrence, which were also the areas of highest faecal contamination and included two transmission foci. Kriging and MaxEnt modeling simulated the scenarios obtained through the kernel analyses. Interpretation & conclusion : Use of geostatistical tools (Kriging and MaxEnt) is efficient for identifying areas at risk and for estimating the dispersal of Biomphalaria species across the study area. Occurrence of B. straminea in the study area is influenced by the rainy season, as it becomes more abundant during the period immediately after the rainy season, increasing the risk of dispersal and the appearance of new transmission foci.
Evaluation of epidemiological, clinical, and laboratory characteristics and mortality rate of patients with Crimean-Congo hemorrhagic fever in the northeast region of Turkey
p. 215
Faruk Karakecili, Aytekin Cikman, Merve Aydin, Umut Devrim Binay, Ozan Arif Kesik, Fatih Ozcicek DOI:10.4103/0972-9062.249479
Background & objectives : Crimean-Congo hemorrhagic fever (CCHF), an illness characterized by fever and hemorrhage, is caused by a CCHF virus (CCHFV). It is an important public health problem in Turkey. The objective of this study was to evaluate the demographic, clinical, and laboratory characteristics and mortality rates of CCHF patients in the northeast region of Turkey. Methods : A total of 206 patients, diagnosed with CCHF, from northeast region of Turkey were included and evaluated between 2011 and 2017. Real-time reverse transcriptase polymerase chain reaction (RT-PCR) and immunofluorescence (IFA) methods were used for the diagnoses. Results : Of the patients included in the study, 77.2% were farmers/livestockers, while 22.8% had other occupations. The incidence of tick bite or tick contact with bare hands was 52.9%. About 94.2% of the patients were living in rural areas and 5.8% in city centers. However, all the patients living in city centers had a history of visit to rural areas. The disease was more common in May, June, and July months. The most common symptoms at the time of admission included fatigue, fever, and widespread body pain, while laboratory findings were thrombocytopenia, leukopenia, and anemia. Bleeding, tachycardia, and rash were the most common findings on physical examination. Of all the patients, 95.6% were identified by RT-PCR and 4.4% by IFA methods. Severe cases constituted 22.3% (46) of the included patients. Throughout the course of this study, 7 (3.4%) patients died, and the remaining 96.6% (199) patients were discharged with a full recovery. Disease severity was significantly correlated with mortality rate and duration of hospitalization (p <0.001 and p = 0.013).Interpretation & conclusion : In this study, the mortality rate observed was lower than that reported in the literature because of accessibility of early supportive therapy. It would be beneficial in CCHF treatment to recognize the disease at an early stage, begin supportive treatment quickly, and educate the people living in high-risk areas as well as health care personnel working in these areas.
Babesiosis prevalence in malaria-endemic regions of Colombia
p. 222
Juliana Gonzalez, Ignacio Echaide, Adriana Pabón, J Juan Gabriel Piñeros, Silvia Blair, Alberto Tobón-Castaño DOI:10.4103/0972-9062.249480
Background & objectives : The presence of Babesia spp in humans, bovine cattle and ticks (the transmitting vector) has not been well characterized in Colombia. Babesia infection in humans can be overlooked due to similarity of the disease symptoms with malaria specially in the regions where malaria is endemic. The aim of the present work was to study the frequency of Babesia infection in humans, bovines and ticks in a malaria endemic region of Colombia, and explore the possible relationship of infection with host and the environmental factors.Methods : A cross-sectional study was carried out between August 2014 and March 2015 to determine the frequency of B. bovis and B. bigemina infection in a sample of 300 humans involved in cattle raising, in 202 bovines; and in 515 ticks obtained from these subjects, using molecular (PCR), microscopic and serological methods. In addition, the demographic, ecological and zootechnical factors associated with the presence of Babesia, were explored. Results : In the bovine population, the prevalence of infection was 14.4% (29/202); the highest risk of infection was found in cattle under nine months of age (OR = 23.9, CI 8.10–94.30, p = 0.0). In humans, a prevalence of 2% (6/300) was found; four of these six cases were positive for B. bovis. Self-report of fever in the last seven days in the positive cases was found to be associated with Babesia infection (Incidence rate ratio = 9.08; CI 1.34–61.10, p = 0.02). The frequency of B. bigemina infection in the collected ticks was 18.5% (30/162). Interpretation & conclusion : The study established the presence of Babesia spp in humans, bovines and ticks. The most prevalent species responsible for babesiosis in humans and bovines was B. bovis, while B. bigemina was the species most frequently found in the tick population. The results contribute to the knowledge of the epidemiology of babesiosis in the country and can provide guidelines for the epidemiological surveillance of this non-malarial febrile illness in humans as well as cattle.
Low susceptibility of domestic cats to experimental Leishmania infantum infection
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Baharak Akhtardanesh, Reza Kheirandish, Iraj Sharifi, Ali Mohammadi, Ali Mostafavi, Tohid Mahmoodi, Mohadesse Ebrahimi DOI:10.4103/0972-9062.249481
Background and objectives : The dogs are considered the main reservoir of visceral leishmaniasis (VL), but lately the disease incidence has been reported in cats also. In this study, the susceptibility of domestic cats to experimental Leishmania infantum infection was assessed by different diagnostic methods. Methods : A total of 12 healthy adult male cats were captured by double door live trap cages containing baits. Of them eight cats were intraperitoneally inoculated with 107 L. infantum promastigotes (stationary phase), and four cats were used as controls. Whole blood and serum samples were collected at weekly intervals for 16 wk after inoculation for testing by polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) methods. Aspirates of prescapular lymph nodes and bone marrow were obtained at monthly intervals. Clinical examination was performed twice weekly and histopathological evaluation was done on necropsy samples at the termination of the study. Results: One week after inoculation, blood nested PCR was able to detect the L. infantum infection and it remained positive until 16 wk. ELISA test remained negative during the study. Amastigote phase of parasite was not observed in bone marrow aspiration and necropsy samples. Interpretation and conclusion :The feline model described in this work would be useful in further understanding of L. infantumimmunopathogenensis in cats. The results of this preliminary study suggest that cats might be resistant to VL as the inoculation dose which induces pathognomonic clinical features in dogs, just creates asymptomatic parasitaemia in cats. Though, due to long-lasting parasitaemia, cats may act as appropriate reservoir for transmission of VL to human population. Further studies are needed to describe the possible role of cats in the epidemiology of VL in endemic areas.
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