Anopheles (Kerteszia) cruzii infected by Plasmodium in the Atlantic Forest indicates that the malaria transmission cycle is maintained even after howler monkeys' population decline.

The Atlantic Forests outside of the Amazon region in Brazil are low-frequency malaria hotspots. The disease behaves as a zoonosis maintained by nonhuman primates (NHPs), especially howler monkeys. Between 2016 and 2018, Brazil witnessed the largest yellow fever outbreak since 1980, resulting in massive declines in these NHP populations. However, reports of malaria cases continued in transmission areas. This scenario motivated this survey to determine the frequency of infection of the anophelines by Plasmodium species. Mosquitoes were captured using Shannon traps and CDC light traps and identified as to species based on morphological characters. The screening for malaria parasites targeted only Anopheles species belonging to the subgenus Kerteszia, the proven primary malaria vector. A TaqMan qPCR assay using ribosomal primers (18S rRNA gene) was performed in a Step One Plus Real-time PCR to detect Plasmodium species. Seven hundred sixty field-caught anophelines divided into 76 pools were examined. Out of 76 tested pools, seven (9.21%) were positive. Three pools were Plasmodium malariae-positive, and four were Plasmodium vivax-positive. The anopheline infection was expressed as the maximum infection rate (MIR), disclosing a value of 0.92%, indicative of a steady state. Such stability after the yellow fever outbreak suggests that other species of NHPs could support transmission.

Residual malaria of Atlantic Forest systems and the influence of anopheline fauna.

In Brazil, the Amazon region comprises 99.5% of the reported malaria cases. However, another hotspot of the disease is the Atlantic Forest regions, with the sporadic occurrence of autochthonous human cases. In such context, this study sought to investigate the role of anopheline mosquitoes (Diptera: Culicidae) in the residual malaria transmission in Atlantic Forest areas. Two rural areas in the Espírito Santo state were the surveyed sites. Mosquitoes were captured using Shannon trap and CDC light traps and identified into species based on morphological characters. Ecological indexes (Shannon-Wiener diversity, Simpson's dominance, Pielou equability, and Sorensen similarity) were the tools used in the anopheline fauna characterization and comparison along with the two explored areas. The assessment of the sampling adequacy in the studied areas was possible through the generation of a species accumulation curve. A correlation test verified the influence of climatic variables on the anopheline species abundance. A total of 1471 female anopheline mosquitoes were collected from May 2019 to April 2020, representing 13 species. The species richness was higher in Valsugana Velha (hypo-endemic) than in Alto Caparaó (non-endemic). There was a significant variation in the species abundance between Valsugana Velha (n = 1438) and Alto Caparaó (n = 33). The most abundant species was Anopheles (Kerteszia) cruzii complex Dyar and Knab, 1908 representing 87% of the total anophelines collected. These results suggest that the Plasmodium spp. circulation in Brazilian Atlantic Forest areas occurs mainly due to the high frequency of Anopheles (K.) cruzii complex, considered the principal vector of simian and human malaria in the region.

Effects of anthropogenic landscape changes on the abundance and acrodendrophily of Anopheles (Kerteszia) cruzii, the main vector of malaria parasites in the Atlantic Forest in Brazil.

BACKGROUND: The mosquito Anopheles (Kerteszia) cruzii is the main vector of human and simian malaria in the Atlantic Forest. This species is usually abundant in the forests where it occurs, preferring to live and feed on canopies, behaviour known as acrodendrophily. However, in several studies and locations this species has been observed in high density near the ground in the forest. In this study, it was hypothesized that factors associated with anthropogenic landscape changes may be responsible for the variation in abundance and acrodendrophily observed in An. cruzii. METHODS: The study was conducted in a conservation unit in the city of São Paulo, Brazil. Monthly entomological collections were performed from March 2015 to April 2017, and the resulting data were used with data from another study conducted in the same area between May 2009 and June 2010. Mosquitoes were collected from five sites using CDC and Shannon traps. Landscape composition and configuration metrics were measured, and generalized linear mixed-effect models were used to investigate the relationship between these metrics and variations in the abundance and acrodendrophily of An. cruzii. RESULTS: The model that showed the best fit for the relationship between landscape metrics and An. cruzii abundance suggests that an increase in the proportion of forest cover leads to an increase in the abundance of this mosquito, while the model that best explained variations in An. cruzii acrodendrophily suggests that an increase in total forest-edge length leads to greater activity by this species at ground level. CONCLUSION: While the data indicate that changes in landscape due to human activities lead to a reduction in An. cruzii abundance, such changes may increase the contact rate between this species and humans living on the edges of forest fragments where An. cruzii is found. Future studies should, therefore, seek to elucidate the effect of these landscape changes on the dynamics of Plasmodium transmission in the Atlantic Forest, which according to some studies includes the participation of simian hosts.

Simian malaria: a narrative review on emergence, epidemiology and threat to global malaria elimination.

Simian malaria from wild non-human primate populations is increasingly recognised as a public health threat and is now the main cause of human malaria in Malaysia and some regions of Brazil. In 2022, Malaysia became the first country not to achieve malaria elimination due to zoonotic simian malaria. We review the global distribution and drivers of simian malaria and identify priorities for diagnosis, treatment, surveillance, and control. Environmental change is driving closer interactions between humans and wildlife, with malaria parasites from non-human primates spilling over into human populations and human malaria parasites spilling back into wild non-human primate populations. These complex transmission cycles require new molecular and epidemiological approaches to track parasite spread. Current methods of malaria control are ineffective, with wildlife reservoirs and primarily outdoor-biting mosquito vectors urgently requiring the development of novel control strategies. Without these, simian malaria has the potential to undermine malaria elimination globally.

Phylogeny of Anopheles (Kerteszia) (Diptera: Culicidae) Using Mitochondrial Genes.

Identification of mosquito species is necessary for determining the entomological components of malaria transmission, but it can be difficult in morphologically similar species. DNA sequences are largely used as an additional tool for species recognition, including those that belong to species complexes. Kerteszia mosquitoes are vectors of human and simian malaria in the Neotropical Region, but there are few DNA sequences of Kerteszia species in public databases. In order to provide relevant information about diversity and improve knowledge in taxonomy of Kerteszia species in Peru, we sequenced part of the mitochondrial genome, including the cytochrome c oxidase I (COI) barcode region. Phylogenetic analyses structured all species of mosquitoes collected in Peru into a single clade, separate from the Brazilian species. The Peruvian clade was composed of two lineages, encompassing sequences from Anopheles Kerteszia boliviensis and Anopheles Kerteszia pholidotus. An. pholidotus sequences were recorded for the first time in Peru, whereas An. boliviensis sequences were for the first time published in the GenBank database. Sequences generated from specimens morphologically identified as Anopheles Kerteszia cruzii clustered into three separate clades according to the collection localities of Serra do Mar, Serra da Mantiqueira, and Serra da Cantareira, confirming An. cruzii as a species complex, composed of at least three putative species.

Malaria epidemiology in low-endemicity areas of the Atlantic Forest in the Vale do Ribeira, São Paulo, Brazil.

We describe a seroepidemiological survey of malaria prevalence in two areas of low endemicity: Intervales State Park and Alto Ribeira State Tourist Park (PETAR). Both are located in the Vale do Ribeira in the state of São Paulo, Brazil. In this study, 318 subjects from both areas had their blood analyzed for the presence of malaria parasites by thin and thick blood smears. One hundred and sixty-three (51.2%) of the subjects were from Intervales State Park and 155 (48.7%) were from PETAR. We analyzed all the samples by indirect immunofluorescent assay (IFA) to detect antibodies against asexual forms of Plasmodium vivax and Plasmodium malariae and enzyme immunosorbent assay (ELISA) to detect the presence of antibodies against circumsporozoite proteins (CSP) from P. vivax VK210, human P. vivax-like/Plasmodium simiovale, P. vivax VK247 and Plasmodium brasilianum/P. malariae. The presence of Plasmodium species was detected by polymerase chain reaction (PCR). Eighteen of the subjects analyzed had positive IFA results for IgM against P. malariae antigens, and three others were positive for P. vivax antigens. Positivity of IgG antibodies against P. vivax detected by IFA was high in samples from both Intervales State Park and PETAR (32.0% and 49.0%, respectively), while positivity for P. malariae was lower (16.0% and 19.3% in Intervales State Park and PETAR, respectively). ELISA tests showed a higher prevalence of antibodies against P. vivax VK210 (35.0%) in samples from Intervales State Park and against human P. vivax-like (29.7%) in samples from PETAR. PCR reactions revealed the presence of parasites in several of the samples analyzed. In Intervales State Park, one subject was infected by P. malariae and two by Plasmodium falciparum, while in PETAR, one subject was positive for P. falciparum and three for both P. falciparum and P. vivax parasites. The areas where these parks are located belong to the Atlantic Forest habitat, and inhabitants frequently, see monkeys. Our data suggest that monkeys may constitute a natural reservoir for malaria in both areas.

Mosquitoes in degraded and preserved areas of the Atlantic Forest and potential for vector-borne disease risk in the municipality of São Paulo, Brazil.

In order to assess the epidemiological potential of the Culicidae species in remaining areas of the Brazilian Atlantic Forest, specimens of this family were collected in wild and anthropic environments. A total of 9,403 adult mosquitoes was collected from May, 2009 to June, 2010. The most prevalent among species collected in the wild environment were Anopheles (Kerteszia) cruzii, the Melanoconion section of Culex (Melanoconion), and Aedes serratus, while the most common in the anthropic site were Coquillettidia chrysonotum/albifera, Culex (Culex) Coronator group, and An. (Ker.) cruzii. Mosquito richness was similar between environments, although the abundance of individuals from different species varied. When comparing diversity patterns between environments, anthropic sites exhibited higher richness and evenness, suggesting that environmental stress increased the number of favorable niches for culicids, promoting diversity. Increased abundance of opportunistic species in the anthropic environment enhances contact with culicids that transmit vector-borne diseases.