**7. Prevention and control**

*L. donovani* is perhaps one of the most virulent *Leishmania* species and is present in South Asian region, one of the highest incidence areas of VL. Between 2005 and 2013, *Leishmania* ranked the second worst next only to malaria among the 16 categories of "neglected tropical diseases" [46]. In 2005 the WHO and the government representatives of India, Nepal, and Bangladesh signed a memorandum of understanding with commitment to mutually cooperate in order to achieve VL elimination from these countries by 2015. The objective was to reduce the annual incidence of VL to below 1/10,000 inhabitants by 2015 using detection and treatment of VL cases and vector control measures [47]. The target was not achieved by the expected date of 2015 due to high cost and limited availability of treatment, lack of effectiveness of vector control measures, emergence of parasite resistance, and low community coverage of health services in all areas. A second target was set for 2017; however, the WHO has recently reset the target of VL elimination from the Indian subcontinent to year 2020 [48]. In the Eastern Mediterranean region, a specific target was set for CL to detect 70% of all cases and at least treat 90% of them. There is crucial gap in planning elimination of VL in Asia and VL and CL in other regions. These elimination campaigns will require more intense work and better strategic planning in addition to the high cost required. Currently, there is increased global awareness about the disease and the dire need for its elimination, in particular, after Asian elimination initiative of VL and 2012 London declaration on neglected tropical diseases. Having said that, many challenges still exist that counteract these efforts. These include poor sanitary conditions, conflict zones leading to forced migration, emerging atypical variants, poor public awareness especially in nonendemic areas, suboptimal diagnostic modalities, and limited treatment options [1, 49].

**Table 6**.

*Parasitology and Microbiology Research*

**312**

*Treatment regimens for visceral leishmaniasis as per WHO recommendations (adopted from WHO) (https://*

*www.who.int/leishmaniasis/research/978924129496\_pp67\_71.pdf?ua=1) [8].*

#### **7.1 Mass treatment**

The VL elimination initiative in the Indian subcontinent in collaboration with the WHO was based on diagnosis and treatment of VL patients using mass treatment to reach the target of reducing the annual VL incidence to below 1/10,000. This plan was dependent on actively looking for and diagnosing *Leishmania* patients. However, the target date was missed because of several factors including limitations of diagnostic tools to diagnose patients actively, lack of health-care coverage in certain areas in developing countries in particular rural regions, lack of proper vector control, and high cost and limited availability of treatment [46–48].

**7.6 Immunization/vaccination**

*DOI: http://dx.doi.org/10.5772/intechopen.90680*

globally, mostly in heavily infested areas.

required for patients with resistant disease.

**7.7 Postinfection immunity**

species in 97–98% of the cases.

**7.8 Long-term monitoring**

**8. Conclusion**

**315**

future.

*Leishmaniasis*

Several candidate vaccines are in preclinical development, and at least three are currently in clinical studies; however, no effective vaccine has been identified to date to effectively prevent human leishmaniasis [51]. Some studies show vaccination by killed *Leishmania* promastigotes, and live BCG can develop protection against CL, but no protection is seen against VL. Approximately 90–98% of leishmaniasis patients recover after disease and develop natural acquired immunity mainly due to Th1 lymphocyte activation and its reaction towards the infecting parasite. This strongly supports the ongoing vaccination development efforts, hopefully looking forward for a clinically efficient vaccine to be available in the near

All the above measures have shown some success; however, they are costly and

require extensive coordination efforts globally. Early diagnosis and treatment remain the main control strategy since untreated patients serve as reservoirs of parasites. In most countries majority of patients present themselves to the health care, suggesting that many cases will remain in the community for long periods before seeking health care due to reduced awareness. Strategy for eradication would require surveillance with early detection and prompt treatment measures applied

Successfully treated patients who receive full course of therapy by effective agents and self-resolving infections generally acquire immunity from the infecting

Prolonged monitoring and follow-up evaluations of patients after successful treatment are recommended for relapse or recurrence of the disease. Yearly followup is recommended for patients infected with *L. braziliensis* for up to a decade for early detection of any progression to mucocutaneous disease. Certain complex cases of ML, diffuse CL, *L. recidivans*, and PKDL can be difficult to treat and may require prolonged therapy. In addition, retreatment and/or second-line medications may be

There has been increasing global awareness about leishmaniasis and the need for its eradication. However, there are many challenges that hinder this global initiative and maintain leishmaniasis as one of the neglected tropical diseases. These challenges include but are not limited to high cost, variability of clinical spectrum, cyclic transmission patterns, changing disease foci, emerging atypical and resistant forms, suboptimal diagnostics, limited treatment options/availability, and suboptimal community awareness and health-care coverage, in particular in nonendemic areas. Several preventive measures using various strategies are needed to tackle personal human protection against infection, interventions targeting vector and animal reservoir control. With the current known challenges and limitations of resources, perhaps integrated approach to control this infection and focus on development of effective vaccine for protection may be a strategic way to use the limited resources available to reach the WHO's set target of leishmaniasis reduction/elimination [17].

#### **7.2 Vector control strategies**

Including insecticide-treated nets and indoor insecticide sprays are used for areas where sandflies bite indoor. Recently resistance to dichlorodiphenyltrichloroethane (DDT) is reported to emerge, and therefore other synthetic products such as pyrethroids started to be used [50]. In areas like Africa where the vector mainly bites outdoor, selective outdoor spraying might be effective in reducing vector density. In addition alternative vector control measures have been proposed and used such as plastering of walls and floors using mud and lime. However these environmental management methods need further evaluation and validation. The KALANET project was the only trial that evaluated the impact of "long-lasting insecticidal nets" on *L. donovani* and concluded that these nets have beneficial effects against *L. donovani* as they provide some degree of personal protection against infection as compared to those using untreated nets or no nets. Further prospective studies are needed to evaluate integrated vector management measures on VL and other vector-borne diseases [47].

#### **7.3 Reservoir eradication/control**

In areas of zoonotic transmission should be effectively targeted to reduce the human infection rate from infected animal reservoir. Several reservoir control measures have been used including animal elimination in certain areas, canine vaccines, and insecticides used on dogs such as spot-on insecticide which are drops applied on skin under the hair in the neck region, insecticide-impregnated dog collars, and whole body insecticide use. Studies on efficacy of animal reservoir intervention programs are limited and show lack of generalizability of intervention measures as well as mixed results [17]. In addition there are also conflicting results on the impact of dogs in transmission of leishmaniasis since not all infected dogs become infectious. All the above factors point towards a fundamental gap in our knowledge of disease biology and its transmission.

#### **7.4 Minimizing outdoor exposure**

At dawn to dusk which are the peak bite times and use of insecticide-treated nets and/or fine-mesh nets since the sandflies are small in size and can pass through standard mosquito nets.

#### **7.5 Transmission via blood**

Infected patients should not donate blood or organs since the parasite can be transmitted through blood.
