Future Model to Control Leishmaniasis
Leishmaniasis is a disease, which is provoked by a parasite (leishmania) that dwells and sustains in cells. It is transmitted by a sandfly that bites animals or human beings. There are different methods of dealing with parasites including residual sprays, space sprays, barriers and treated netting/clothing, tropical repellents, and reservoir burrows applications. Nevertheless, the Indian subcontinent requires different methods of dealing with the problem, specifically cheap model to control sandflies or mosquitoes, which can be implemented through biological control. Solanum jasminoides, Ricinus communis, and Bougainvillea are among the most important plants, which can be located close to human and animal settlements in order to attract mosquitoes, kill them and prevent leishmania.
Leishmania appears to be of the trypanosomatida protozoon genus. It practically means that the parasite dwells and remains in cells provoking the illness, which is transferred to hosts through the bite of the female sandfly. It is a neglected tropical disease, which leads to lethal effects if not medicated and controlled. The current paper will demonstrate how to target leishmaniasis elimination in Indian subcontinent by controlling the mosquito vector. The old and current techniques utilized in preventing and controlling the disease are not always sustainable and suitable for the area. Thus, it requires an alternative which could deal with the problem effectively. The paper will suggest a future cheap model to control sandflies and mosquitoes through biological control. The model will regard growing certain plants, which are toxic to sandflies and can help in preventing leishmaniasis if planted in border zones.
Leishmaniasis and the Indian Subcontinent
In regard to the Indian subcontinent (ISC), leishmaniasis is provoked by the protozoon leishmania donovani that is transferred by the peri-domestic female sandflies. Leishmaniasis appears to be an ignored tropic affection, which hazards the health and life of approximately 300 million people globally, majorly influencing the poorest individuals in the indigent rural locations. Two thirds of the above-mentioned figures occur in the ISC every year. In addition, more than 20,000 deaths per year in the Indian subcontinent are imputed to leishmaniasis, which makes this disease the most death-dealing and lethal parasitical contagion after malaria. Human beings are regarded to be the mere hosts for leishmania donovani in the Indian subcontinent. In fact, only a minor part of the people, who become contaminated, evolves clinical symptoms. At the same time, the major part of remaining individuals appears to be asymptomatic while transmitting the parasite. People who manifest symptoms of leishmaniasis reveal the signs of febricity, weight loss, anemia and abnormal enlargement of the spleen, and might ultimately die if left untreated.
It is highly important to mention that leishmania is the trypanosomatida protozoon genus. The parasite dwells and remains in cells provoking the illness, is transferred to hosts through the bite of the female sandfly. The initial hosts stand for vertebrates and commonly contaminated animals including domestic cats, dogs, black rats, opossums, and the crab-eating foxes. More than 30 kinds of sandfly are believed to be incriminated in spreading of leishmania parasites. Sandflies can be discovered close to human villages and settlements and typically inhabit in organic matter encompassing leaf litter, compost, fertilizers, and rodent holes and dens. These parasites are frequently categorized in accordance with locations where the parasites rest and bite. Thus, in regard to the biting locations, they can be categorized as either exophagic (outdoors) or endophagic (indoors) and, as for the resting locations, they appear to be either exophilic (outdoors) or endophilic (indoors).
The Review of the Old and Current Techniques Used to Eliminate Sandfly and Prevent Leishmaniasis
The mere noted vector of the leishmaniasis disease stands for little dipteral flies outlined commonly as a ‘sandfly’. Sandflies, similarly to all true flies of Diptera order, experience full transformation and display four downright life stages including egg, larva, pupa and the adult, imago. In contradiction to other mosquitoes, the unripe stages do not require stagnant water in order to finish the evolvement. Nevertheless, the insects need warm and moist setting, similar to one prevailing in the Indian subcontinent.
In fact, many researchers believe that one reason for the resurgence of leishmaniasis stands for a diminution in the usage of insecticides for mosquito control. The majority of adult sandflies control implements can be classified into six categories encompassing residual sprays, space sprays, barriers and treated netting/clothing, tropical repellents, and reservoir burrows applications. The first method includes the utilization of long-range insecticides to surfaces and interior walls in order to either eliminate or repel biting insects. The second method incorporates the dissipation of an insecticide in droplets or smoke in order to kill insects in the treated space while leaving minor residual impact.
Some of the facts demonstrate that residual spraying of animal shelters and houses is apparently the most helpful and the most employed. Numerous insecticides are available for potential use. The research of four sandfly species shows that DDT and malathion demonstrate less sandfly toxicity contrary to newer pyrethroid insecticides encompassing resmethrin and cyfluthrin. In fact, DDT appeared to be the first insecticide utilized on a large scale for sandflies control. It was utilized in huge quantities in India, China, Brazil, the Soviet Union, etc. After all, this measure led to appreciable deprivations in sandfly populace. Nevertheless, the researches did not demonstrate that the reduction in the quantity of insects has ultimately a direct impact on disease risk. Some particularized evidence has been utilized to insinuate the efficiency of sandfly control in lowering disease risks. One of the best samples stands for the visceral leishmaniasis control syllabus performed in Bihar (India) in 1958-1970. This was the time when no visceral leishmaniasis cases were reported in the location. Nevertheless, the affection has emerged soon after the syllabus cessation. On the other hand, the shift from organophosphates and organochlorines to newer pyrethroid insecticides equipped numerous innovative forceful chemicals to be used in a form of residual sprays. Thus, when deltamethrin has been implemented for both exterior and interior applications, inward sandfly populations were essentially lowered. At the same time, the external sprays appeared to be inefficient.
Numerous environmental agents encompassing elevated summer temperatures, solid radiation, and the conglomeration of dust restrict the utilization of residual sprays. These circumstances can lower insecticide toxicity or effectiveness. Nine discrepant insecticides including organophosphates, pyrethroids, and carbamate were utilized for this purpose in a form of residual sprays, space sprays, and dustings for animal burrows. Regardless the usage of a broad diapason of implements and chemicals, the program appeared to have restricted success in lowering sandfly populace. There was a small lowering in sandfly bites after residual applications to tent walls. It is important to mention that the research revealed the pesticides appearance as primary irritant for insects, provoking sandflies to elevate biting ratios. The effectiveness of an inner residual spray is undermined by lethal impacts of the spray on the target vector population. Deterrence and contact aggravation might appear as more important in securing humans from subjection to vectors than in the deadly impact of the insecticide.
Space sprays also appear to be constituents of some sandfly control programs. The technique can be both interior and exterior applications, but they do not leave essential and serious residual impacts because of being targeted at the insects in the environment at the time of the spray dispersion (typically the flying insects). Nevertheless, these sprays reveal disappointing impacts as DDT and malathion fogs were inefficient in lowering sandfly populace, and the outcomes appeared as minor and non-durable. However, the facts demonstrate that inward fogs are still used as a constituent of programs, which can only equip provisional facilitation from insect bites.
Insecticide-treated nets (ITNs) appeared to be one of the oldest and the most efficient methods of lowering the human-vector exposure in intraregional and peri-domestic transfer of leishmaniasis disease. The major principle of this technique stands for the ‘baited traps’ operations, in which the odor of the sleeper acts as a lure, whereas the technique offers a restrictive and impermeable effect. Nevertheless, the efficiency of incondite bednets as a technique for preventing parasite transmission relies on provocation size and conduct of the vector in regard to the biting practice together with the general sleeping habits. The current practice demonstrates that the result of this preventative method should be taken in the interpretation with numerous unrelated factors because sticky traps might be affected by the design of houses. Moreover, as Indian subcontinent is characterized by hot weather, the majority of people using bednets with fine mesh in similar weather settings describe the technique as unpleasant to be utilized because the premises are poorly ventilated. Therefore, the Indian subcontinent requires techniques, which are appropriately designed in terms of the environmentally sensitive nature of the region. Another generalized technique concerns household insecticide spraying programs. Nevertheless, they appear to be useful in locations, where the sandfly is probable to contact with the actually sprayed walls. However, there is undeniable evidence regarding the fact that sandfly is actually resistant to insecticides. Moreover, its resistance is practically growing to such insecticide as DDT, which is currently utilized in large-scale spraying programs in India. There are no facts demonstrating vividly that spraying campaigns appear to be more efficient directly before transmission seasons. As transmission seasons are highly discrepant from location to location in the Indian subcontinent, there is a high necessity to ensure that spraying programs are diligently performed with respect to transferring,and transmission seasons and also parasite activity in order to have the highest probability of being efficient. Despite the fact that insecticide spraying is currently utilized during leishmaniasis epidemics in India, its misuse typically leads to prevalent and extensive resistance. This actually makes the technique useless when it is the most required in the Indian subcontinent.
Future Cheap Biological Control Model
Highly scant data is available in regard to the biological control of sandfly species. Nevertheless, numerous laboratory studies demonstrate that infection of sandflies with discrepant organisms including fungi, bacilli viruses, and nematodes can be characterized as the possibility to kill adult and pre-adult sandflies. In addition, some plants such as Ricinus communis, Solanum jasminoides, and Bougainvillea glabra appear to be highly toxic for adult sandflies. They can be utilized in a form of sugar source for sandflies, which actually helps in killing mosquitoes. Therefore, it is recommended to plant Solanum jasminoides, Bougainvillea glabra, Ricinus communis, etc. in barrier zones (insects’ breeding and habitat areas that include organic waste such as feces, manure, rodent burrows, leaf litter, etc). It equips a decreased cost, stable and sustainable alternative to insecticide usage which appears to be rarely inefficient in controlling and preventing sandflies and leishmaniasis. In addition, there are other specific plants, including Derris amazonica (Papillionaceae) and Antonia ovata (Loganiaceae), which appear to be effective in killing female sandflies with high probability of 80-100%. Mosquito feeding on these plants not only lowers sandfly survival rates, but also incurs negative impacts on fertility. The results of numerous studies demonstrate that growing in high densities of above-mentioned plants in sandflies endemic locations can lower populace sizes and diminish the hazard of leishmania infections. Moreover, the neem (Azadirachta indica) oil has a deterrence activity against sanflies when utilized for three days at 1-2% concentrations. The active ingredient azadirachtin appears to kill sandfly larvae. There are other toxic plant extracts including dried leaf extracts of Antonia ovata (Loganiaceae) and Derris amazonica (Papillionaceae), which also may kill from 80 to 100% of sandfly females. The repellency effect of the garlic (known as Allium sativum) oil is also beneficial in regard to 97% of efficacy as for repelling sandfly females. Some plants including Solanum jasminoides, Ricinus communis, Bougainvillea glabra appear to be toxic for adult sandflies and might thus appear to be a straightly accessible alternative to the gainful insecticides for sandfly control.
The paper demonstrates that the Indian subcontinent appears to be a suitable location for sandfly species, which means that classical methods of controlling and preventing leishmaniasis disease appear to be helpful only temporarily. Solanum jasminoides, Bougainvillea glabra, Ricinus communis appear to be key determinants of the sandfly lifecycle, which means that plants diet can also affect insect reproductive strategies and the life history traits. It appears that these plants might present a direct accessible alternative to commercial insecticides for sandflies control. The toxicity of these plants for sandflies (both adult and pre-adult forms) makes the biological control model a low-cost sustainable alternative to ineffective insecticide utilization in preventing leishmaniasis. It is suggested to use the combination of above-mentioned plants with plant extracts that can attract mosquitoes, kill them, and prevent leishmania.
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