Current vector control challenges in the fight against malaria in Brazil

Abstract

In Brazil, malaria is an important public health problem first reported in 1560. Historically, fluctuations in malaria cases in Brazil are attributed to waves of economic development; construction of railroads, highways, and hydroelectric dams; and population displacement and land occupation policies. Vector control measures have been widely used with an important role in reducing malaria cases. In this review article, we reviewed the vector control measures established in the Brazilian territory and aspects associated with such measures for malaria. Although some vector control measures are routinely used in Brazil, many entomological and effectiveness information still need better evidence in endemic areas where Plasmodium vivax predominates. Herein, we outlined some of the needs and priorities for future research: a) update of the cartography of malaria vectors in Brazil, adding molecular techniques for the correct identification of species and complexes of species; b) evaluation of vector competence of anophelines in Brazil; c) strengthening of local entomology teams to perform vector control measures and interpret results; d) evaluation of vector control measures, especially use of insecticide-treated nets and long-lasting insecticidal nets, estimating their effectiveness, cost-benefit, and population acceptance; e) establishment of colonies of malaria vectors in Brazil, i.e., Anopheles darlingi, to understand parasite-vector interactions better; f) study of new vector control strategies with impacts on non-endophilic vectors; g) estimation of the impact of insecticide resistance in different geographical areas; and h) identification of the relative contribution of natural and artificial breeding sites in different epidemiological contexts for transmission.

Efficacy of insecticides used in indoor residual spraying for malaria control: an experimental trial on various surfaces in a “test house”

“…Some limitations in Anopheles neotropical bioassays include a lack of mosquito colonization in laboratory circumstances and low availability of bioassays, except for colonies of Anopheles aquasalis and Anopheles albitarsis sensu stricto, which were kept in a laboratory by the Oswaldo Cruz Foundation in Rio de Janeiro, Brazil [12, 13]. Therefore, it is a priority to establish colonies of vectors that transmit malaria in Brazil [14]. Although malaria represents a serious public health problem in Brazil, few studies have evaluated the resistance of vectors to insecticides [15, 16].…”

Vector-focused Approaches to Curb Malaria Transmission in the Brazilian Amazon: An Overview of Current and Future Challenges and Strategies

“…Accordingly, in Brazil, the Ministry of Health recommends the distribution and installation of LLINs, which are intended for personal overnight protection. Currently, LLINs impregnated with pyrethroid have a shelf life of 2-3 years [82]. Insecticide-treated bed-net incorporating a mixture of the pyrethroid alpha-cypermethrin and pyriproxyfen, an insect growth regulator, has been proposed as an alternative to pyrethroid only nets.…”

“…Etofenprox PM 20% is the insecticide used in Brazil for residual spraying for malaria vector control. This product has a residual effect for 4 months requiring three annual applications [82]. In the Amazon, factors such as the operational cost of mobilizing teams to perform insecticide spraying, the difficulty in accessing remote areas at adequate frequency, the variability of dwellings, and variable environmental conditions, may compromise the efficacy of IRS [88].…”

“…In the Amazon, factors such as the operational cost of mobilizing teams to perform insecticide spraying, the difficulty in accessing remote areas at adequate frequency, the variability of dwellings, and variable environmental conditions, may compromise the efficacy of IRS [88]. In fact, few systematic evaluations on the impact these measures have on suppressing anopheline populations and reducing levels of malaria transmission in the Brazilian Amazon have been performed [82,88]. While IRS is applicable and effective in urban and peri-urban environments, issues need to be addressed regarding gold miners who often live in huts without walls, continuously exposed to mosquito bites, unconventional indigenous house architecture that may not favor IRS and the lack of studies regarding the stability of insecticides applied on unconventional surfaces and under extreme humidity and temperature environmental conditions [89].…”

Anopheles control is considerably more complicated than Aedes control

“…To reduce malaria transmission, a successful programmer needs to focus on several aspects, including early diagnosis, use of effective antimalarial drugs, and vector control 11 . These strategies are critical for malaria elimination.…”