Perceived needs of disease vector control programs: A review and synthesis of (sub)national assessments from South Asia and the Middle East.

Systems for disease vector control should be effective, efficient, and flexible to be able to tackle contemporary challenges and threats in the control and elimination of vector-borne diseases. As a priority activity towards the strengthening of vector control systems, it has been advocated that countries conduct a vector-control needs assessment. A review was carried out of the perceived needs for disease vector control programs among eleven countries and subnational states in South Asia and the Middle East. In each country or state, independent teams conducted vector control needs assessment with engagement of stakeholders. Important weaknesses were described for malaria, dengue and leishmaniases regarding vector surveillance, insecticide susceptibility testing, monitoring and evaluation of operations, entomological capacity and laboratory infrastructure. In addition, community mobilization and intersectoral collaboration showed important gaps. Countries and states expressed concern about insecticide resistance that could reduce the continued effectiveness of interventions, which demands improved monitoring. Moreover, attainment of disease elimination necessitates enhanced vector surveillance. Vector control needs assessment provided a useful planning tool for systematic strengthening of vector control systems. A limitation in conducting the vector control needs assessment was that it is time- and resource-intensive. To increase the feasibility and utility of national assessments, an abridged version of the guidance should focus on operationally relevant topics of the assessment. Similar reviews are needed in other regions with different contextual conditions.

Coverage evaluation of mass drug administration with triple drug regimen in an evaluation unit in Nagpur district of Maharashtra, India.

BACKGROUND: Triple drug regimen (IDA; Ivermectin, Diethylcarbamazine, Albendazole) recommended for accelerating elimination of lymphatic filariasis was launched in India in December 2018. Nagpur district in Maharashtra was one of the first five districts where this strategy was introduced. The National Vector Borne Disease Control Programme (NVBDCP) at the district reported ~85.0% treatment coverage in the first round of mass drug administration (MDA) with IDA implemented in EU-2 in Nagpur district in January 2019. As per the national guideline, a coverage evaluation survey was carried out and both quantitative and qualitative data were collected to assess the treatment coverage, the level of community preparation and identify the gaps, if any, for improvement. METHODOLOGY: A Coverage Evaluation Survey (CES) following the WHO recommended protocol was conducted in one of the two evaluation units (EU-2) in Nagpur district in March 2019. Coverage Sample Builder (CSB) V2.9 tool was used to calculate the sample size, select sites and estimate drug coverage. The CSB tool followed a two-stage cluster sampling procedure to select 30 primary sampling units (ward/village as a cluster) and a list of random numbers for selecting households (HHs) in each cluster. The results were analyzed for operational indicators. Stata ver. 14.0 software was used to construct the 95% confidence limits accounting for clustering. RESULTS: A total of 1601 individuals aged 5-85 years of both gender from 328 HHs were surveyed from the 30 randomly selected clusters in EU-2. The mean age was 33.8±17.6 years. Among the surveyed population, 78.0% received the drugs (programme reach) and 66.1% consumed the drugs (survey coverage). Survey coverage was significantly higher in rural (82.6%) than in urban (59.4%) and peri-urban (58.6%) areas (P<0.001). Directly observed treatment (DOT) among the surveyed population was 51.6%. Adverse events were reported among 6.9% respondents who reported to have consumed the drugs. CONCLUSION: The IDA based MDA strategy could achieve just the required level of treatment coverage (~65%) in EU-2, Nagpur district, which had previously undergone several rounds of DA-MDAs (Diethylcarbamazine, Albendazole). Having achieved an effective treatment coverage of >80% in rural areas, the coverage in urban and peri-urban areas need to be improved in order to attain the impact of IDA-MDA. It is imperative to strengthen drug delivery and community preparation activities along with improved DOT especially in urban and peri-urban areas to achieve the required level of treatment coverage. Addition of ivermectin did not have any additional perceived adverse events.

Validating the Association of Japanese Encephalitis Vector Abundance with Paddy Growth, Using MODIS Data.

Japanese encephalitis (JE) is one of the leading causes of viral encephalitis in Southeast Asia, particularly India. The major vector transmitting the disease, Culex tritaeniorhynchus, breeds in paddy field and its associated water bodies. The incidence of human infection usually occurs after the peak in vector abundance. Earlier, an association between JE vector abundance and paddy growth was demonstrated in Bellary district of Karnataka state, India, using radar satellite (RISAT 1) data. In this study, an attempt has been made to validate this phenomenon with the data collected from Uttar Pradesh state, using moderate resolution imaging spectroradiometer data.

A Preliminary Study to Forecast Japanese Encephalitis Vector Abundance in Paddy Growing Area, with the Aid of Radar Satellite Images.

Vector mosquitoes of Japanese encephalitis (JE) breed mostly in rice fields, and human cases occur scattered over extended rural rice-growing areas. From this, one may surmise an ecological connection with the irrigation facilities and paddy cultivation. Furthermore, it has been hypothesized that a particular stage of paddy growth is a premonitory sign that can lead to a markedly increased population of the vector mosquitoes. The present study aimed to forecast the vector abundance by monitoring the paddy growth using remote sensing and geographical information systems. The abundance of the JE vector Culex tritaeniorhynchus peaked when the paddy crop was at its heading stage and dipped when the crop reached the maturing stage. A significant positive correlation was observed between paddy growth and adult density (r = 0.73, p < 0.008). The sigma naught values (σ0) derived from satellite images of paddy fields ranged from -18.3 (during transplantation stage) to approximately -10 (during the noncultivation period). A significant positive correlation was observed between σ0 and paddy growth stages (r = 0.87, p < 0.05) and adult vector density (r = 0.74, p = 0.04). The σ0 value observed during the vegetative and flowering stages of paddy growth ranged from -17.6 to -17.16, at which period the vector density started building up. This could be the spectral signature that denotes the "risk," following which a high vector abundance is expected during heading stage of the paddy.

Role of traditional antimalarial plants in the battle against the global malaria burden.

Malaria continues to be a major global public health problem with 3.3 billion people at risk in 106 endemic countries. Globally, over 1000 plants have been used as potential antimalarials in resource-poor settings due to fragile health-care systems and lack of accessibility and affordability of artemisinin-based combination therapies (ACTs). Although many believe that the use of medicinal plants that have folklore reputations for antimalarial properties is relatively safe, many herbs may be potentially toxic due to their intrinsic adverse side effects. Therefore, herbal-derived remedies require powerful and deep assessment of their pharmacological qualities to establish their mode of action, safety, quality, and efficacy. In addition, the evolution of drug resistance also demands new antimalarial agents. This can be achieved by forming a vibrant antimalarial discovery pipeline among all stakeholders, including traditional healers, ethnobotanists, scientists, entomologists, pharmacists, and research institutions, for the isolation and characterization of the bioactive compounds with the ultimate objective of finding novel modes of action antimalarial compounds that can be used to fight against drug-resistant malarial parasites.

Lymphatic filariasis transmission risk map of India, based on a geo-environmental risk model.

The strategy adopted by a global program to interrupt transmission of lymphatic filariasis (LF) is mass drug administration (MDA) using chemotherapy. India also followed this strategy by introducing MDA in the historically known endemic areas. All other areas, which remained unsurveyed, were presumed to be nonendemic and left without any intervention. Therefore, identification of LF transmission risk areas in the entire country has become essential so that they can be targeted for intervention. A geo-environmental risk model (GERM) developed earlier was used to create a filariasis transmission risk map for India. In this model, a Standardized Filariasis Transmission Risk Index (SFTRI, based on geo-environmental risk variables) was used as a predictor of transmission risk. The relationship between SFTRI and endemicity (historically known) of an area was quantified by logistic regression analysis. The quantified relationship was validated by assessing the filarial antigenemia status of children living in the unsurveyed areas through a ground truth study. A significant positive relationship was observed between SFTRI and the endemicity of an area. Overall, the model prediction of filarial endemic status of districts was found to be correct in 92.8% of the total observations. Thus, among the 190 districts hitherto unsurveyed, as many as 113 districts were predicted to be at risk, and the remaining at no risk. The GERM developed on geographic information system (GIS) platform is useful for LF spatial delimitation on a macrogeographic/regional scale. Furthermore, the risk map developed will be useful for the national LF elimination program by identifying areas at risk for intervention and for undertaking surveillance in no-risk areas.

Detection of Chikungunya virus in wild populations of Aedes albopictus in Kerala State, India.

We detected Chikungunya virus (CHIKV) infection among wild populations of Aedes albopictus female specimens during the CHIKV outbreaks of 2009 and 2006 collected in different localities in Kerala State, India. The envelope 1 gene (E1) sequences of the virus isolate 2009 from the mosquito species showed close genetic relatedness (Kimura 2 Parameter genetic distance=0.0013) to CHIKV-positive isolates from human serum samples from the same area. E1 gene sequences from Ae. albopictus, as well as from human isolates, had the crucial non-synonymous C/T mutation at position 10670, leading to the A226V amino acid change. This natural inclination indicated the role of this mosquito species in the transmission of CHIKV during its recent outbreaks in Kerala State.

Chikungunya virus outbreak in Kerala, India, 2007: a seroprevalence study

India was affected by a major outbreak of chikungunya fever caused by Chikungunya virus (CHIKV) during 2006-2007. Kerala was the worst affected state during 2007 with a contribution of 55.8 percent suspected cases in the country. However, except for clinically reported case records, no systematic information is available on infection status of CHIKV in the region. Hence, we carried out a post-epidemic survey to estimate seroprevalence status [immunoglobulin G (IgG)] in the community using commercially available indirect immunofluorescence test. This methodology had been reported to be highly specific and sensitive for CHIKV infection. The study area selected was the worst affected mid-highlands region of Kerala which harbour vast area of rubber plantations. The study evidenced 68 percent of the population to be seropositive for CHIKV IgG. Males were found more affected than females (χ2 = 9.86; p = 0.002). Among males, prevalence was significantly higher in the age classes 21-30 (χ2 = 5.46; p = 0.019) and 31-40 (χ2 = 5.84; p = 0.016) years. This may be due to high occupational risk of the male population engaged in plantation activities exposed to infective bites of Aedes albopictus. The current study provides an insight into the magnitude of CHIKV outbreak in Kerala.

Chikungunya virus outbreak in Kerala, India, 2007: a seroprevalence study.

India was affected by a major outbreak of chikungunya fever caused by Chikungunya virus (CHIKV) during 2006-2007. Kerala was the worst affected state during 2007 with a contribution of 55.8% suspected cases in the country. However, except for clinically reported case records, no systematic information is available on infection status of CHIKV in the region. Hence, we carried out a post-epidemic survey to estimate seroprevalence status [immunoglobulin G (IgG)] in the community using commercially available indirect immunofluorescence test. This methodology had been reported to be highly specific and sensitive for CHIKV infection. The study area selected was the worst affected mid-highlands region of Kerala which harbour vast area of rubber plantations. The study evidenced 68% of the population to be seropositive for CHIKV IgG. Males were found more affected than females (χ2 = 9.86; p = 0.002). Among males, prevalence was significantly higher in the age classes 21-30 (χ2 = 5.46; p = 0.019) and 31-40 (χ2 = 5.84; p = 0.016) years. This may be due to high occupational risk of the male population engaged in plantation activities exposed to infective bites of Aedes albopictus. The current study provides an insight into the magnitude of CHIKV outbreak in Kerala.

Field trials on the efficacy of DEET-impregnated anklets, wristbands, shoulder, and pocket strips against mosquito vectors of disease.

A field trial was undertaken in order to determine the efficacy of DEET (N,N-diethyl-m-toluamide) impregnated anklets, wristbands, shoulder and pocket fabric strips against mosquito vectors of disease. The present study was conducted in the urban locality of Pondicherry, India. Human test subjects were exposed to natural populations of mosquitoes for a 12 h (18.00-06.00) night time period. The fabric strips (anklets, wristbands, shoulder, and pocket strips) were impregnated with DEET at two different concentrations of 1.5 mg/cm(2) and 2.0 mg/cm(2). The results clearly revealed that DEET-impregnated anklets, wristbands, shoulder and pocket fabric strips were found more effective against mosquitoes remarkably. The DEET-impregnated anklets, wristbands, shoulder and pocket fabric strips at a concentration of 2 mg/cm(2) provided 5 h complete protection against mosquitoes bites and the reduction of man-landing rate varied between 65.85 and 100%. However, DEET-impregnated fabric strips at a concentration of 1.5 mg/cm(2) provided 4 h complete protection against mosquito bites and the reduction of man-landing rate varied between 51.21 and 100%. The final results clearly demonstrate that repellent activity of DEET-impregnated anklets, wristbands, shoulder, and pocket strips were dose-dependent. Certainly, the DEET-impregnated fabric strips can be used as an effective potential personal protection measure in order to avoid those insects/mosquitoes that prefer to feed outdoors or those that feed in the early evening.

Relative efficacy of repellent-treated wristbands against three major mosquito (Diptera: Culicidae) vectors of disease, under laboratory conditions.

A laboratory study was carried out to evaluate the relative efficacy of N-N-diethyl-m-toluamide (DEET)- and N,N-diethyl phenylacetamide (DEPA)-treated wristbands against three major vector mosquitoes viz., Anopheles stephensi Liston, Culex quinquefasciatus Say and Aedes aegypti (L.), at two different concentrations viz., 1.5 and 2.0 mg/cm(2). Overall, both DEET and DEPA have shown various degrees of repellency impact against all three vector mosquitoes. DEET offered the highest 317.0 min mean complete protection against An. stephensi and DEPA provided 275.6 min complete protection to Cx. quinquefasciatus at 2.0 mg/cm(2). However, DEPA-treated wristbands did not show any significant differences in terms of reduction of human landing rate and mean complete protection time against An. stephensi and Ae. aegypti between 1.5 and 2.0 mg/cm(2). DEET demonstrated relatively higher repellency impact to vector mosquitoes than DEPA. However, χ(2) analysis revealed that there was no statistically significant difference found in repellent efficiency between DEET and DEPA (P = 0.924). The present study result suggests that repellent-treated wristbands could serve as a means of potential personal protection expedient to avoid insect's annoyance and reduce vector-borne disease transmission. They are extremely valuable whenever and wherever other kinds of personal protection measures are unfeasible.

Delimitation of lymphatic filariasis transmission risk areas: a geo-environmental approach.

BACKGROUND: The Global Programme to Eliminate Lymphatic Filariasis (GPELF) depends upon Mass Drug Administration (MDA) to interrupt transmission. Therefore, delimitation of transmission risk areas is an important step, and hence we attempted to define a geo-environmental risk model (GERM) for determining the areas of potential transmission of lymphatic filariasis. METHODS: A range of geo-environmental variables has been selected, and customized on GIS platform to develop GERM for identifying the areas of filariasis transmission in terms of "risk" and "non-risk". The model was validated through a 'ground truth study' following standard procedure using GIS tools for sampling and Immuno-chromotographic Test (ICT) for screening the individuals. RESULTS: A map for filariasis transmission was created and stratified into different spatial entities, "risk' and "non-risk", depending on Filariasis Transmission Risk Index (FTRI). The model estimation corroborated well with the ground (observed) data. CONCLUSION: The geo-environmental risk model developed on GIS platform is useful for spatial delimitation purpose on a macro scale.