Optimiration Modelfor leishmaniasis control: epidemiological and eco- nomical analisis

Author(s)

Hélio Junji Shimozako

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina (FM/SBD)
• Defense date: 2015-11-11

Examining board members

Eduardo Massad; Marcelo Nascimento Burattini; Maria Irma Seixas Duarte; Eunice Aparecida Bianchi Galati; Dirce Maria Trevisan Zanetta

• Advisor: Eduardo Massad

Abstract

Zoonotic visceral leishmaniasis (ZVL) is one of the most important emerging parasitic diseases. Brazil, in particular, is considered one of the countries in which this disease is most endernic. Despite the publication of visceral leishmaniasis control guidelines and the investment in health services and controljpreventive activities, the vectors and reser- voirs in urban areas are the major challenge for those control programs. This is due to (1) the need for better comprehension regarding the vector behavior in the urban envi- ronment; (2) the operating difficulties in perforrning the activities in time to reach good results; and (3) the high cost of those activities. The main objective of this study was to elaborate an optirnization model for leishmaniasis control. This model is based on 5 con- trol parameters that correspond to the following strategies: (I) vector population control, (11) elirnination of positive dogs, (111) use of insecticide-impregnated dog collars, (IV) dog vaccination and (V) dog treatment. This model was elaborated using an equation system, composed of 17 differential equations, 4 of which represent the disease dynarnic on hu- man population (susceptible (Xh), latent (Ih), clinically ill (Yh) and recovered humans (Zft)), 10 for dog population (susceptible (Xd and xcd), latent (ld and Icd), clinically ill (Yd and Ycd), recovered (Zd and zcd) and vaccinated dogs (Vd and vcd), where C represents the categories using the insecticide-impregnated dog collars) and 3 for vector population (non-infected (SI), infected but not infective (S2), infected and infective sandflies (S3)). For econornic analysis of those control strategies, we estimated the cost of them per dog (in the case of vector control population, it was estimated per treated house). Regarding the nume- rical simulations without the control strategies, the endernic equilibrium densities were: Xh = 0.394, Ih = 0.0305, Yh = 0.00167, Zh = 0.574, Xd = 0.314, Id = 0.165, Yd = 0.0163, Zd = 0.505, SI = 0.709, S2 = 0.0858 and S3 = 0.205. In endernic equilibrium state, the basic reproduction number and the rate of reported human cases per day were estimated as 1%0 = 4.50 and R = 3.58 x 1O-6/day, respectively. Considering the impact evaluation of controI strategies, the vector population control was the strategy that resulted in a fas- ter decrease in the rate of human reported cases per day and, consequently, in the larger reduction of medical and hospital costs too. However, the investment (that is, the cost) of the vector population control was the highest one. On the other hand, the investment in elirninating positive dogs was considered the lowest one. Since those control strategies operate at different points within the epiderniological chain, the planning a control, while taking into account the simultaneous action of these strategies, could not only result in a more interesting control strategy, but could also improve the optirnization of investments on visceralleishmaniasis control (AU)

• FAPESP's process: 11/02633-5 - Optimization model for leishmaniasis control: epidemiological and economical analysis
• Grantee: Hélio Junji Shimozako
• Support Opportunities: Scholarships in Brazil - Doctorate