Malaria Severity in Mangaluru City in the Southwestern Coastal Region of India.

Dakshina Kannada district in the Southwestern region of Karnataka state, India, including Mangaluru city is endemic to malaria. About 80% of malaria infections in Mangaluru and its surrounding areas are caused by Plasmodium vivax and the remainder is due to Plasmodium falciparum. Malaria-associated clinical complications significantly occur in this region. Here, we report the pathological conditions of 41 cases of fatal severe malaria, admitted to the district government hospital in Mangaluru city during January 2013 through December 2016. The results of clinical, hematological, and biochemical analyses showed that most of these severe malaria cases were associated with thrombocytopenia, anemia, metabolic acidosis, acute respiratory distress, and single or multi-organ dysfunction involving liver, kidney, and brain. Of the 41 fatal malaria cases, 24, 10, and seven patients had P. vivax, P. falciparum, and P. vivax and P. falciparum mixed infections, respectively. These data suggest that besides P. falciparum that is known to extensively cause severe and fatal malaria illnesses, P. vivax causes fatal illnesses substantially in this region, an observation that is consistent with recent findings in other regions.

Influence of midgut microbiota in Anopheles stephensi on Plasmodium berghei infections.

BACKGROUND: The native gut microbiota of Anopheles mosquitoes is known to play a key role in the physiological function of its host. Interestingly, this microbiota can also influence the development of Plasmodium in its host mosquitoes. In recent years, much interest has been shown in the employment of gut symbionts derived from vectors in the control of vector-borne disease transmission. In this study, the midgut microbial diversity has been characterized among laboratory-reared adult Anopheles stephensi mosquitoes, from the colony created by rearing progeny of wild-caught mosquitoes (obtained from three different locations in southern India) for multiple generations, using 16S ribosomal RNA (rRNA) gene sequencing approach. Further, the influence of native midgut microbiota of mosquitoes on the development of rodent malaria parasite Plasmodium berghei in its host has been studied. METHODS: The microbial diversity associated with the midgut of An. stephensi mosquitoes was studied by sequencing V3 region of 16S ribosomal RNA (rRNA) gene. The influence of native midgut microbiota of An. stephensi mosquitoes on the susceptibility of the mosquitoes to rodent malaria parasite P. berghei was studied by comparing the intensity and prevalence of P. berghei infection among the antibiotic treated and untreated cohorts of mosquitoes. RESULTS: The analysis of bacterial diversity from the midguts of An. stephensi showed Proteobacteria as the most dominant population among the three laboratory-reared strains of An. stephensi studied. Major genera identified among these mosquito strains were Acinetobacter, Pseudomonas, Prevotella, Corynebacterium, Veillonella, and Bacillus. The mosquito infectivity studies carried out to determine the implication of total midgut microbiota on P. berghei infection showed that mosquitoes whose native microbiota cleared with antibiotics had increased susceptibility to P. berghei infection compared to the antibiotic untreated mosquitoes with its natural native microbiota. CONCLUSIONS: The use of microbial symbiont to reduce the competence of vectors involved in disease transmission has gained much importance in recent years as an emerging alternative approach towards disease control. In this context, the present study was aimed to identify the midgut microbiota composition of An. stephensi, and its effect on the development of P. berghei. Interestingly, the analysis of midgut microbiota from An. stephensi revealed the presence of genus Veillonella in Anopheles species for the first time. Importantly, the study also revealed the negative influence of total midgut microbiota on the development of P. berghei in three laboratory strains of An. stephensi, emphasizing the importance of understanding the gut microbiota in malaria vectors, and its relationship with parasite development in designing strategies to control malaria transmission.

Field testing & evaluation of the efficacy & duration of effectiveness of a biolarvicide, Bactivec® SC (Bacillus thuringiensis var. israelensis SH-14) in Bengaluru, India.

Background & objectives: Different formulations of Bacillus thuringiensis var. israelensis (Bti) have been tested against different mosquito vectors and other insects for their residual activity. In the present study, the efficacy and residual activity of a new formulation of Bti (Bactivec Suspension Concentrate) were evaluated against immature stages of Anopheles stephensi Liston (Diptera: Culicidae), Aedes aegypti Linnaeus (Diptera: Culicidae) and Culex quinquefasciatus Say (Diptera: Culicidae), in natural habitats in Phase II and Phase III in Bengaluru, India. Methods: Preferential breeding habitats of the mosquito species were selected and four dosages (0.25, 0.5, 1 and 2 ml/50 l) were tested in Phase II trial. Two most effective dosages, 0.5 and 1 ml/50 l were selected for Phase III trial. The evaluation was carried out essentially following the guidelines of the World Health Organization Pesticide Evaluation Scheme. Pre-treatment and post-treatment densities were recorded at regular intervals, and >80 per cent reduction in pupae was taken as the duration of effectiveness. Results: Bactivec SC treated at the dosage of 1 ml/50 l could produce 10-17 days efficacy (>80% reduction in pupae) in clean water habitats tested, whereas 0.5 ml/50 l dosage showed residual activity from 7 to 14 days against Ae. aegypti and An. stephensi in Phase III studies. In polluted water habitats, 4-7 days efficacy could be recorded against Cx. quinquefasciatus in Phase III. Interpretation & conclusions: The Bactivec SC formulation was operationally feasible and easy to handle. For the control of Anopheles and Aedes mosquitoes in freshwater habitats, 1 ml/50 l dosage was found effective, whereas in polluted water habitats against Cx. quinquefasciatus 5 ml/m2 was found effective.

Comparative efficacy of two poeciliid fish in indoor cement tanks against chikungunya vector Aedes aegypti in villages in Karnataka, India.

BACKGROUND: In 2006, severe outbreaks of Aedes aegypti-transmitted chikungunya occurred in villages in Karnataka, South India. We evaluated the effectiveness of combined information, education and communication (IEC) campaigns using two potential poeciliid larvivorous fish guppy (Poecilia reticulata) and mosquitofish (Gambusia affinis), in indoor cement tanks for Aedes larval control. METHODS: Trials were conducted in two villages (Domatmari and Srinivaspura) in Tumkur District from March to May 2006 for Poecilia and one village (Balmanda) in Kolar District from July to October 2006 for Gambusia. A survey on knowledge, attitude and practice (KAP) on chikungunya was initially conducted and IEC campaigns were performed before and after fish release in Domatmari (IEC alone, followed by IEC + Poecilia) and Balmanda (IEC + Gambusia). In Srinivaspura, IEC was not conducted. Larval surveys were conducted at the baseline followed by one-week and one-month post-intervention periods. The impact of fish on Aedes larvae and disease was assessed based on baseline and post-intervention observations. RESULTS: Only 18% of respondents knew of the role of mosquitoes in fever outbreaks, while almost all (n = 50 each) gained new knowledge from the IEC campaigns. In Domatmari, IEC alone was not effective (OR 0.54; p = 0.067). Indoor cement tanks were the most preferred Ae. aegypti breeding habitat (86.9%), and had a significant impact on Aedes breeding (Breteau Index) in all villages in the one-week period (p < 0.001). In the one-month period, the impact was most sustained in Domatmari (OR 1.58, p < 0.001) then Srinivaspura (OR 0.45, p = 0.063) and Balmanda (OR 0.51, p = 0.067). After fish introductions, chikungunya cases were reduced by 99.87% in Domatmari, 65.48% in Srinivaspura and 68.51% in Balmanda. CONCLUSIONS: Poecilia exhibited greater survival rates than Gambusia (86.04 vs.16.03%) in cement tanks. Neither IEC nor Poecilia alone was effective against Aedes (p > 0.05). We conclude that Poecilia + IEC is an effective intervention strategy. The operational cost was 0.50 (US$ 0.011, 1 US$= 47) per capita per application. Proper water storage practices, focused IEC with Poecilia introductions and vector sanitation involving the local administration and community, is suggested as the best strategy for Aedes control.

Effectiveness of a new granular formulation of biolarvicide Bacillus thuringiensis Var. israelensis against larvae of malaria vectors in India.

Control of vector(s) or mosquitoes, in general, through biolarvicide as an alternate biocontrol agent is a greatest desire. We evaluated a water-dispersible granular formulation biolarvicide Bacillus thuringiensis var. israelensis (Bti, H-14 serotype; VectoBac(®) WDG) in the laboratory and also in the field against two principal malaria vectors, Anopheles culicifacies and Anopheles stephensi. Laboratory evaluations against laboratory-reared immature of the two species were carried out at a temperature of 28°C ± 2°C and 70%-80% relative humidity. Field trials were conducted in a rural area and in Bangalore city, Karnataka, South India. First trial against the rural vector An. culicifacies was carried out in stone quarry pits at dosages of 0.05, 0.2, and 1 g/m(2). The second trial against urban vector An. stephensi was carried out in ring wells at 0.05, 0.1, 0.2, 0.5, and 1 g/m(2) dosages. Laboratory tests revealed increased efficacy against An. stephensi. The fifty percent lethal concentration (LC(50)) and LC(90) values against An. culicifacies and An. stephensi were 0.348 and 1.008 mg/L (χ(2) = 8.49; p > 0.05) and 0.245 and 0.533 mg/L (χ(2) = 4.67; p < 0.05), respectively. Based on the findings of no pupal production in the field, the formulation was effective up to 14 days at 0.2 g/m(2) or more appropriately at 0.25 g/m(2) dose for both the species under field conditions. We discuss how this new formulation was evaluated against An. culicifacies and An. stephensi under laboratory and field conditions. No adverse effects were observed on the nontarget species such as frogs, their tadpoles, small local fish, Notonectid bugs, and water scatters. We conclude that VectoBac WDG is effective at 0.25 g/m(2) and be recommended for its use in the vector-borne disease control program under integrated vector management concept.

Prevalence of malaria, dengue, and chikungunya significantly associated with mosquito breeding sites.

OBJECTIVES: To observe the prevalence of malaria, dengue, and chikungunya and their association with mosquito breeding sites. METHODS: The study was observational and analytical. A total of 162 houses and 670 subjects were observed during the study period. One hundred forty-two febrile patients were eligible for the study. After obtaining informed consent from all febrile patients, 140 blood samples were collected to diagnose malaria, dengue, and chikungunya. Larval samples were collected by the standard protocol that follows. Correlation of data was performed by Pearson correlation test. RESULTS: Forty-seven blood samples were found positive: 33 for chikungunya, 3 for dengue, and 11 for malaria. Fifty-one out of 224 larval samples were found positive. Out of the 51 positive samples, 37 were positive for Aedes, 12 were positive for Anopheles, and two were positive for Culex larvae. INTERPRETATION AND CONCLUSION: Mosquito-borne fevers, especially malaria, dengue, and chikungunya, have shown a significant relationship with mosquito breeding sites.

Reduced susceptibility to selected synthetic pyrethroids in urban malaria vector Anopheles stephensi: a case study in Mangalore city, South India.

BACKGROUND: Synthetic pyrethroids are potent insecticides most commonly used in the vector control programme. These are applied for indoor residual sprays, space sprays and in impregnated bed nets. Resistance reduces the efficacy of insecticides. Thus, the susceptibility status of the target vector(s) is monitored routinely to select the effective ones. A study was undertaken in a malaria endemic coastal city Mangalore, Karnataka, South India, against the known malaria vector Anopheles stephensi. METHODS: The susceptibility status was assessed at diagnostic doses of DDT (4%), malathion (5%), deltamethrin (0.05%), cyfluthrin (0.15%), alphacypermethrin (0.10%), lambdacyhalothrin (0.05%) and permethrin (0.75%) using the standard WHO tube test method during October/November 2006. RESULTS: Anopheles stephensi was resistant to malathion by 54.9%, but tolerant to deltamethrin by 86.1%, cyfluthrin 95.5% and alphacypermethrin 90.6%, whereas it was susceptible to DDT by 98.1%, lambdacyhalothrin 98.6% and permethrin 100.0%, respectively. The KDT50 and KDT95 values for these insecticides also showed the similar responses. CONCLUSION: Susceptibility of An. stephensi to DDT is an important finding as this has never been used in Mangalore city, whereas its rural counterpart Anopheles culicifacies is widely resistant to this insecticide. The study explores the selection and rotation of the appropriate insecticide molecule even within the same group for effective vector management.

Observations on sporozoite detection in naturally infected sibling species of the Anopheles culicifacies complex and variant of Anopheles stephensi in India.

Sporozoites were detected in naturally infected sibling species of the primary rural vector Anopheles culicifacies complex in two primary health centres (PHCs) and a variant of the urban vector Anopheles stephensi in Mangalore city, Karnataka, south India while carrying out malaria outbreak investigations from 1998-2006. Sibling species of An. culicifacies were identified based on the banding patterns on ovarian polytene chromosomes, and variants of An. stephensi were identified based on the number of ridges on the egg floats. Sporozoites were detected in the salivary glands by the dissection method. Of the total 334 salivary glands of An. culicifacies dissected, 17 (5.08%) were found to be positive for sporozoites. Of the 17 positive samples, 11 were suitable for sibling species analysis; 10 were species A (an efficient vector) and 1 was species B (a poor vector). Out of 46 An. stephensi dissected, one was sporozoite positive and belonged to the type form (an efficient vector). In malaria epidemiology this observation is useful for planning an effective vector control programme, because each sibling species/variant differs in host specificity, susceptibility to malarial parasites, breeding habitats and response to insecticides.

A community-based health education programme for bio-environmental control of malaria through folk theatre (Kalajatha) in rural India.

BACKGROUND: Health education is an important component in disease control programme. Kalajatha is a popular, traditional art form of folk theatre depicting various life processes of a local socio-cultural setting. It is an effective medium of mass communication in the Indian sub-continent especially in rural areas. Using this medium, an operational feasibility health education programme was carried out for malaria control. METHODS: In December 2001, the Kalajatha events were performed in the evening hours for two weeks in a malaria-affected district in Karnataka State, south India. Thirty local artists including ten governmental and non-governmental organizations actively participated. Impact of this programme was assessed after two months on exposed vs. non-exposed respondents. RESULTS: The exposed respondents had significant increase in knowledge and change in attitude about malaria and its control strategies, especially on bio-environmental measures (p < 0.001). They could easily associate clean water with anopheline breeding and the role of larvivorous fish in malaria control. In 2002, the local community actively co-operated and participated in releasing larvivorous fish, which subsequently resulted in a noteworthy reduction of malaria cases. Immediate behavioural changes, especially maintenance of general sanitation and hygiene did not improve as much as expected. CONCLUSION: This study was carried out under the primary health care system involving the local community and various potential partners. Kalajatha conveyed the important messages on malaria control and prevention to the rural community. Similar methods of communication in the health education programme should be intensified with suitable modifications to reach all sectors, if malaria needs to be controlled.