Reemergence of human malaria in Atlantic Forest of Rio Grande do Sul, Brazil

Unforeseen Plasmodium infections in the Atlantic Forest of Brazilian Extra-Amazonian region could jeopardise malaria elimination. A human malaria case was registered in Três Forquilhas, in the Atlantic Forest biome of Rio Grande do Sul, after a 45 years' time-lapsed without any malaria autochthonous notification in this southern Brazilian state. This finding represents the expansion of the malaria distribution areas in Brazil and the southernmost human malaria case record in South America in this decade. The coexistence of the bromeliad-breeding vector Anopheles (Kerteszia) cruzii and non-human primates in the Atlantic Forest regularly visited by the patient claimed for the zoonotic origin of this infection. The reemergence of Atlantic Forest human malaria in Rio Grande do Sul was also discussed.

Novel molecular evidence of population structure in Anopheles (Kerteszia) bellator from Brazilian Atlantic Forest

Anopheles bellator is a primary malaria vector in the Atlantic Forest. Partial sequences of timeless and Clock genes were used to assess the genetic differentiation of five Brazilian populations, which showed strong population structure (e.g. high F ST values and fixed differences) in all pairwise comparisons between Bahia sample and the others from Paraná, São Paulo and Rio de Janeiro states. Also, the resulting phylogenetic trees clearly grouped the sequences from Bahia in a different cluster with high bootstrap values. Among southern and southeastern populations low levels of genetic differentiation were found suggesting a general stability of the genetic structure.

Anopheles (Kerteszia) cruzii (DIPTERA: CULICIDAE) IN PERIDOMICILIARY AREA DURING ASYMPTOMATIC MALARIA TRANSMISSION IN THE ATLANTIC FOREST: MOLECULAR IDENTIFICATION OF BLOOD-MEAL SOURCES INDICATES HUMANS AS PRIMARY INTERMEDIATE HOSTS / Anopheles (Kerteszia) cruzii (Diptera: Culicidae) em área peridomiciliar durante transmissão de malária assintomática na Mata Atlântica: identificação molecular das fontes de repasto sanguíneo indica humanos como hospedeiros intermediários primários

Anopheles (Kerteszia) cruzii has been implicated as the primary vector of human and simian malarias out of the Brazilian Amazon and specifically in the Atlantic Forest regions. The presence of asymptomatic human cases, parasite-positive wild monkeys and the similarity between the parasites infecting them support the discussion whether these infections can be considered as a zoonosis. Although many aspects of the biology of An. cruzii have already been addressed, studies conducted during outbreaks of malaria transmission, aiming at the analysis of blood feeding and infectivity, are missing in the Atlantic Forest. This study was conducted in the location of Palestina, Juquitiba, where annually the majority of autochthonous human cases are notified in the Atlantic Forest of the state of São Paulo. Peridomiciliary sites were selected for collection of mosquitoes in a perimeter of up to 100 m around the residences of human malaria cases. The mosquitoes were analyzed with the purpose of molecular identification of blood-meal sources and to examine the prevalence of Plasmodium. A total of 13,441 females of An. (Ker.) cruzii were collected. The minimum infection rate was calculated at 0.03% and 0.01%, respectively, for P. vivax and P. malariae and only human blood was detected in the blood-fed mosquitoes analyzed. This data reinforce the hypothesis that asymptomatic human carriers are the main source of anopheline infection in the peridomiciliary area, making the probability of zoonotic transmission less likely to happen.

Anopheles (Kerteszia) cruzii é o vetor primário das malárias humana e simiana fora da Amazônia Brasileira e especificamente nas regiões de Mata Atlântica. A presença de casos humanos assintomáticos, macacos silvestres positivos para Plasmodium e a similaridade entre os parasitas que os infectam suportam a discussão se essas infecções podem ser consideradas como zoonoses. Embora muitos aspectos da biologia de An. cruzii já tenham sido abordados, estudos conduzidos durante surtos de transmissão de malária, visando a análise de repasto sanguíneo e infectividade, são ausentes na Mata Atlântica. Este estudo foi conduzido na localidade de Palestina, Juquitiba, Mata Atlântica do Estado de São Paulo, onde anualmente a maioria dos casos humanos autóctones é notificada. Locais em peridomicílio foram selecionados para coleta de mosquitos em um perímetro de até 100 m em torno das residências de casos humanos de malária e da floresta circundante. Os mosquitos foram analisados com o objetivo de identificação molecular das fontes de repasto sanguíneo e para examinar a prevalência de Plasmodium. Um total de 13.441 fêmeas de An. (Ker.) cruzii foi coletado. A taxa de infecção mínima foi calculada a 0,03% e 0,01%, respectivamente, para P. vivax e P. malariae e somente sangue humano foi detectado nos mosquitos analisados que se alimentaram com sangue. Nossos dados reforçam a hipótese de que os portadores humanos assintomáticos são a principal fonte de infecção para os anofelinos na área do peridomicílio, tornando a transmissão zoonótica improvável.

Morphology of the larvae, male genitalia and DNA sequences of Anopheles (Kerteszia) pholidotus (Diptera: Culicidae) from Colombia

Since 1984, Anopheles (Kerteszia) lepidotus has been considered a mosquito species that is involved in the transmission of malaria in Colombia, after having been incriminated as such with epidemiological evidence from a malaria outbreak in Cunday-Villarrica, Tolima. Subsequent morphological analyses of females captured in the same place and at the time of the outbreak showed that the species responsible for the transmission was not An. lepidotus, but rather Anopheles pholidotus. However, the associated morphological stages and DNA sequences of An. pholidotus from the foci of Cunday-Villarrica had not been analysed. Using samples that were caught recently from the outbreak region, the purpose of this study was to provide updated and additional information by analysing the morphology of female mosquitoes, the genitalia of male mosquitoes and fourth instar larvae of An. pholidotus, which was confirmed with DNA sequences of cytochrome oxidase I and rDNA internal transcribed spacer. A total of 1,596 adult females were collected in addition to 37 larval collections in bromeliads. Furthermore, 141 adult females, which were captured from the same area in the years 1981-1982, were analysed morphologically. Ninety-five DNA sequences were analysed for this study. Morphological and molecular analyses showed that the species present in this region corresponds to An. pholidotus. Given the absence of An. lepidotus, even in recent years, we consider that the species of mosquitoes that was previously incriminated as the malaria vector during the outbreak was indeed An. pholidotus, thus ending the controversy.

Anthropophilic biting behaviour of Anopheles (Kerteszia) neivai Howard, Dyar & Knab associated with Fishermen’s activities in a malaria-endemic area in the Colombian Pacific

On the southwest Pacific Coast of Colombia, a field study was initiated to determine the human-vector association between Anopheles (Kerteszia) neivai and fishermen, including their nearby houses. Mosquitoes were collected over 24-h periods from mangrove swamps, marshlands and fishing vessels in three locations, as well as in and around the houses of fishermen. A total of 6,382 mosquitoes were collected. An. neivai was most abundant in mangroves and fishing canoes (90.8%), while Anopheles albimanus was found indoors (82%) and outdoors (73%). One An. neivai and one An. albimanus collected during fishing activities in canoes were positive for Plasmodium vivax , whereas one female An. neivai collected in a mangrove was positive for P. vivax . In the mangroves and fishing canoes, An. neivai demonstrated biting activity throughout the day, peaking between 06:00 pm-07:00 pm and there were two minor peaks at dusk and dawn. These peaks coincided with fishing activities in the marshlands and mangroves, a situation that places the fishermen at risk of contracting malaria when they are performing their daily activities. It is recommended that protective measures be implemented to reduce the risk that fishermen will contract malaria.

Isolamento do flavivírus Iguape a partir de mosquitos Anopheles (Kerteszia) cruzii em Juquitiba - Estado de Säo Paulo - Brasil / Isolation of flavivirus Iguape from mosquitoes Anopheles (Kerteszia) cruzii in Juqutiba - Säo Paulo State - Brazil

O flavivírus Iguape foi isolado pela primeira vez em 1979, a partir de camundongo sentinela, exposto em floesta no Município de Iguape, Estado de Säo Paulo, Brasil. Anticorpos inibidores da hemaglutinaçäo, monotípicos para o vírus Iguape, foram detectados em animais domésticos e silvestres na Regiäo do Vale do Ribeira, SP. Anticorpos monotípicos têm sido também detectados em soros humanos, embora näo haja evidência de doença clínica. O estudo foi realizado em maio de 1994, no Município de Juquitiba, SP, em área de floresta. Mosquitos foram capturados com armadilhas luminosas. Após identificaçäo sistemática, lotes de cerca de 30 mosquitos da mesma espécie foram processados para isolamento de vírus, empregando-se camundongos. A identificaçäo foi realizada por testes de Hemaglutinaçäo, Inibiçäo de Hemaglutinaçäo, Fixaçäo de Complemento, Neutralizaçäo em camundongos e sensibilidade ao desoxicolato de Sódio. Uma cepa de vírus (SPAr-158482) foi obtida apartir de mosquitos Anopheles (Kerteszia) cruzii. O agente isolado apresentou significante sensibilidade ao Desoxicolato de Sódio. A sorologia por Inibiçäo de Hemaglutinaçäo, Fixaçäo de Complemento e Neutralizaçäo em camundongos, indicou que a cepa isolada é idêntica ao vírus Iguape. Esses achados sugerem que o An. cruzii pode desenpenhar algum papel no ciclo de transmissäo do vírus Iguape, em ambientes naturais. (AU)

The flavivirus Iguape was isolated for the first time in 1979, from a sentinel mouse exposed in a forested area in Iguape County - SP, Brazil. Monotypic hemagglutination inhibition antibodies for Iguape virus were detected in domestic and sylvan animals, in Ribeira Valley region, S"o Paulo State. Monotypic antibodies have also been detected in human sera, although there is no evidence of clinical disease. The authors report the isolation of a new strain of Iguape virus from naturally infected mosquitoes. The study was conducted in May, 1994 in Juquitiba County ñ S"o Paulo State, in a forested area.Mosquitoes were captured by light traps . After systematics identification, pools of mosquitoes were processed for virus isolation in suckling mice. An isolate (SPAr-158482) was obtained from Anopheles (Kerteszia) cruzii. Tests of Hemagglutination, Hemagglutination Inhibition, Complement Fixation, Neutralization in suckling mice and sensitivity to Sodium Deoxycholate were employed for identification. (AU)