Transmission of residual malaria of the Atlantic forest systems in Espírito Santo: vector behavior and molecular characterization of the circulating species of Plasmodium.
Name: JULYANA CERQUEIRA BUERY
Type: PhD thesis
Publication date: 22/03/2018
Advisor:
Name |
Role |
|---|---|
| CRISPIM CERUTTI JUNIOR | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| CRISPIM CERUTTI JUNIOR | Advisor * |
| GUSTAVO ROCHA LEITE | External Examiner * |
| LILIANA CRUZ SPANO | Internal Examiner * |
| MOISES PALACI | Internal Examiner * |
Summary: In the Southern and Southeastern regions of Brazil, autochtonous malaria cases can
be found close to the Atlantic Forest fragments. In Espírito Santo state, this disease is
particularly frequent, and Plasmodium vivax is the parasite commonly recognized as
the etiological agent of human infections. However, when spatial and temporal
distances between the reported cases and the behavior of local insect vectors,
especially the Anopheles (Kerteszia) cruzii, are observed the transmission cycle does
not correspond to the traditional cycle of malaria. Thus, the hypothesis of the existence
of a zoonosis, with infected simians maintaining the transmission, was established.
Considering that there are obscure aspects regarding bromeliad-malaria, as it is called,
the evaluation of the components of the transmission cycle is necessary. In the present
study, the transmission of bromeliad-malaria in the rural endemic region of Espírito
Santo is investigated based on two main pillars: behavioral analysis of the Anopheles
vectors, mainly those of the subgenus Kerteszia, and comparison of the complete
mitochondrial genome from several isolates of Plasmodium spp. The isolates were
infecting humans, simians of the genus Allouata and mosquitoes Anopheles spp. from
the same region. Light CO2 traps (CDC-CO2) were installed in open areas, inside the
forest and at its edge, and Shannon traps were installed on the edge of the forest. The
mitochondrial genome of Plasmodium spp. found in the different hosts was completely
sequenced and compared in a haplotype network that included all sequences of P.
vivax/simian mitochondrial genomes from samples from humans and simians from
other regions of Brazil. A total of 1,414 anophelines were captured from 13 species.
Anopheles (Kerteszia) cruzii Dyar&Knab continued to be the more captured species in
the forest canopy and was also the vector with the highest prevalence of Plasmodium
vivax infection according to molecular PCR techniques. The haplotype network
indicated that humans and simians of the Atlantic Forest were infected by the same
haplotype, but some isolates of humans are not identical to the simian isolate. In
addition, DNA of Plasmodium spp. extracted from mosquitoes presented sequences
different from those obtained from simians, but similar to those retrieved from two
isolates from humans. This study revealed that the acrodendrophilic behavior of
vectors, especially those infected, reinforces the hypothesis that the presence of P.
vivax in these specimens arises from the blood of animals that live in the top of the
trees, such as monkeys. The comparison of the mitochondrial genomes of the
parasites shows that, in the Atlantic Forest, especially in Espírito Santo, parasites with
similar molecular structures are shared by humans and simians. The recognized
identity between P. vivax and P. simium, the shared haplotypes, and the participation
of the same vector in the transmission of the infection to both host species indicates
interspecies transfer of the parasites.
