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1.
BMC Infect Dis ; 20(1): 333, 2020 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-32393183

RESUMO

BACKGROUND: Malaria is a life threating vector borne disease caused by different Plasmodium parasites. Metema and Armachiho are two of the top five malaria endemic areas among the districts of Amhara region in Ethiopia. Transmission pattern is seasonal and migrant laborers who visit these areas for employment in mechanized agriculture are highly affected. The aim of this study was to investigate seasonal abundance, abdominal status and parity rate of An.gambiae s.l in Metema-Armachiho lowlands, Northwest Ethiopia. METHOD: A 1 year longitudinal entomological study was conducted in Metema-Armachiho lowlands from June 2016-May 2017. Mosquitoes were collected using CDC-light traps in indoor and outdoor sites for four consecutive days in each month. A total of eight standard battery operated CDC-light traps were used to collect mosquitoes. Female mosquitoes were classed as unfed, fed or gravid under a dissecting microscope. The ovaries of all unfed An.gambiae s.l mosquitoes were examined for evidence of parity. Data were entered and analyzed using SPSS-20 software. Chi-square test was applied to show significant difference between variables. P-value< 0.05 was taken as statistically significant. RESULTS: Of the total 1253 mosquitoes collected, 713 (552 female, 161 male) were culex and 540 (501 female, 39 male) were An.gambiae s.l. About 50.9% were collected in June-August 2016, 21.7% in September-November 2016, 12.0% in December 2016-February 2017 and 15.4% in March to May 2017. Of the total, 57.2 and 42.8% of the An.gambiae s.l were collected from indoor and outdoor sites respectively. Of the total females collected, 76.8% were unfed; of which 69.4% were parous. Significantly higher number of female An.gambiae s.l were collected in indoor and there was significant difference in abdominal status of An.gambiae s.l mosquitoes collected in different season (P < 0.05). CONCLUSIONS: Highest number of An.gambiae s.l was observed from June-August followed by September-November. The parity rate of An.gambiae s.l was high and there was significant difference in abdominal status of An.gambiae s.l collected in different season.


Assuntos
Anopheles/parasitologia , Malária/epidemiologia , Malária/transmissão , Mosquitos Vetores/parasitologia , Paridade , Estações do Ano , Animais , Entomologia/métodos , Etiópia/epidemiologia , Feminino , Humanos , Estudos Longitudinais , Malária/parasitologia , Masculino , Plasmodium , Gravidez
2.
Lancet ; 395(10232): 1292-1303, 2020 04 18.
Artigo em Inglês | MEDLINE | ID: mdl-32305094

RESUMO

BACKGROUND: Long-lasting insecticidal nets (LLINs) are the primary malaria prevention tool, but their effectiveness is threatened by pyrethroid resistance. We embedded a pragmatic cluster-randomised trial into Uganda's national LLIN campaign to compare conventional LLINs with those containing piperonyl butoxide (PBO), a synergist that can partially restore pyrethroid susceptibility in mosquito vectors. METHODS: 104 health sub-districts, from 48 districts in Uganda, were randomly assigned to LLINs with PBO (PermaNet 3.0 and Olyset Plus) and conventional LLINs (PermaNet 2.0 and Olyset Net) by proportionate randomisation using an iterative process. At baseline 6, 12, and 18 months after LLIN distribution, cross-sectional surveys were done in 50 randomly selected households per cluster (5200 per survey); a subset of ten households per cluster (1040 per survey) were randomly selected for entomological surveys. The primary outcome was parasite prevalence by microscopy in children aged 2-10 years, assessed in the as-treated population at 6, 12, and 18 months. This trial is registered with ISRCTN, ISRCTN17516395. FINDINGS: LLINs were delivered to households from March 25, 2017, to March 18, 2018, 32 clusters were randomly assigned to PermaNet 3.0, 20 to Olyset Plus, 37 to PermaNet 2.0, and 15 to Olyset Net. In the as-treated analysis, three clusters were excluded because no dominant LLIN was received, and four clusters were reassigned, resulting in 49 PBO LLIN clusters (31 received PermaNet 3.0 and 18 received Olyset Plus) and 52 non-PBO LLIN clusters (39 received PermaNet 2.0 and 13 received Olyset Net). At 6 months, parasite prevalence was 11% (386/3614) in the PBO group compared with 15% (556/3844) in the non-PBO group (prevalence ratio [PR] adjusted for baseline values 0·74, 95% CI 0·62-0·87; p=0·0003). Parasite prevalence was similar at month 12 (11% vs 13%; PR 0·73, 95% CI 0·63-0·85; p=0·0001) and month 18 (12% vs 14%; PR 0·84, 95% CI 0·72-0·98; p=0·029). INTERPRETATION: In Uganda, where pyrethroid resistance is high, PBO LLINs reduced parasite prevalence more effectively than did conventional LLINs for up to 18 months. This study provides evidence needed to support WHO's final recommendation on use of PBO LLINs. FUNDING: The Against Malaria Foundation, UK Department for International Development, Innovative Vector Control Consortium, and Bill and Melinda Gates Foundation.


Assuntos
Mosquiteiros Tratados com Inseticida/estatística & dados numéricos , Malária/prevenção & controle , Sinergistas de Praguicidas/farmacologia , Butóxido de Piperonila/farmacologia , Animais , Anopheles/parasitologia , Anopheles/fisiologia , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Resistência a Inseticidas , Malária/sangue , Masculino , Mosquitos Vetores/parasitologia , Mosquitos Vetores/fisiologia , Uganda
3.
Parasit Vectors ; 13(1): 12, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31924253

RESUMO

BACKGROUND: Urbanization is occurring rapidly on a global scale and is altering mosquito communities, creating assemblages that are characteristically less diverse. Despite high rates of urbanization and ample examples of vector-borne diseases transmitted by multiple species, the effects of urbanization-driven mosquito diversity losses on disease transmission has not been well explored. We investigated this question using the dog heartworm, a filarial parasite vectored by numerous mosquito species. METHODS: We trapped host-seeking mosquitoes in undeveloped areas and neighborhoods of different ages in Wake County, North Carolina, USA, analyzing captured mosquitoes for heartworm DNA. We compared within-mosquito heartworm infection across land-use types by Kruskal-Wallis and likelihood ratio tests. Using zip code level data acquired from dogs in a local shelter, we performed linear regressions of within-host heartworm prevalence by within-mosquito heartworm prevalence as well as by three mosquito diversity measures. We also determined the best predictor of host-level prevalence among models including within-mosquito infection, mosquito diversity and abundance, and socioeconomic status as variables. RESULTS: Suburban areas had lower within-mosquito heartworm prevalence and lower likelihood of heartworm-positive mosquitoes than did undeveloped field sites, although no differences were seen between suburban and undeveloped wooded sites. No relationships were noted between within-mosquito and within-host heartworm prevalence. However, mosquito diversity metrics were positively correlated with host heartworm prevalence. Model selection revealed within-host prevalence was best predicted by a positive relationship with mosquito Shannon-Wiener diversity and a negative relationship with household income. CONCLUSIONS: Our results demonstrate that decreases in mosquito diversity due to urbanization alter vector-borne disease risk. With regard to dog heartworm disease, this loss of mosquito diversity is associated with decreased heartworm prevalence within both the vector and the host. Although the response is likely different for diseases transmitted by one or few species, mosquito diversity losses leading to decreased transmission could be generalizable to other pathogens with multiple vectors. This study contributes to better understanding of the effects of urbanization and the role of vector diversity in multi-vectored pathosystems.


Assuntos
Aedes/parasitologia , Dirofilaria immitis/parasitologia , Dirofilariose/transmissão , Mosquitos Vetores/parasitologia , Animais , Culicidae , Dirofilariose/parasitologia , Vetores de Doenças , Doenças do Cão/transmissão , Cães , Meio Ambiente , North Carolina , Prevalência , Urbanização
4.
Parasit Vectors ; 13(1): 17, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31924276

RESUMO

BACKGROUND: The efficacy of long-lasting insecticidal nets (LLINs) in preventing malaria in Africa is threatened by insecticide resistance. Bioassays assessing 24-hour mortality post-LLIN exposure have established that resistance to the concentration of pyrethroids used in LLINs is widespread. However, although mosquitoes may no longer be rapidly killed by LLIN exposure, a delayed mortality effect has been shown to reduce the transmission potential of mosquitoes exposed to nets. This has been postulated to partially explain the continued efficacy of LLINs against pyrethroid-resistant populations. Burkina Faso is one of a number of countries with very high malaria burdens and pyrethroid-resistant vectors, where progress in controlling this disease has stagnated. We measured the impact of LLIN exposure on mosquito longevity in an area of the country with intense pyrethroid resistance to establish whether pyrethroid exposure was still shortening mosquito lifespan in this setting. METHODS: We quantified the immediate and delayed mortality effects of LLIN exposure using standard laboratory WHO cone tests, tube bioassays and experimental hut trials on Anopheles gambiae populations originating from the Cascades region of Burkina Faso using survival analysis and a Bayesian state-space model. RESULTS: Following single and multiple exposures to a PermaNet 2.0 LLIN only one of the four mosquito populations tested showed evidence of delayed mortality. No delayed mortality was seen in experimental hut studies using LLINs. A delayed mortality effect was only observed in WHO tube bioassays when deltamethrin concentration was increased above the standard diagnostic dose. CONCLUSIONS: As mosquito pyrethroid-resistance increases in intensity, delayed effects from LLIN exposure are substantially reduced or absent. Given the rapid increase in resistance occurring in malaria vectors across Africa it is important to determine whether the failure of LLINs to shorten mosquito lifespan is now a widespread phenomenon as this will have important implications for the future of this pivotal malaria control tool.


Assuntos
Anopheles , Inseticidas/farmacologia , Malária/prevenção & controle , Controle de Mosquitos , Animais , Bioensaio , Burkina Faso , Resistência a Inseticidas , Mosquiteiros Tratados com Inseticida/parasitologia , Mortalidade , Mosquitos Vetores/parasitologia , Nitrilos/farmacologia , Piretrinas/farmacologia
5.
PLoS Negl Trop Dis ; 14(1): e0007862, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31978060

RESUMO

BACKGROUND: Lymphatic filariasis (LF) is targeted for elimination by the year 2020. As of 2017, 67 of the 72 endemic countries have implemented annual Mass Drug Administration (MDA) for interrupting LF transmission. Transmission Assessment Survey (TAS) is the recommended protocol to evaluate the impact of MDA and to decide when to stop MDA in an Evaluation Unit (EU, population ≤2 million). As the human infection levels go down with repeated MDA rounds, it becomes a challenge to select the appropriate survey methods to assess transmission interruption. This study validates a standard protocol for molecular xenomonitoring of infection in vectors (MX) at an EU as a complementary tool for TAS to stop MDA and its utility for post-MDA or post-validation surveillance. METHODOLOGY: The study was conducted in Cuddalore district, Tamil Nadu, India, which was found eligible for TAS after 15 annual rounds of MDA (4 with DEC alone and 11 with DEC plus albendazole). The district was divided into two EUs as per the TAS protocol and one EU was randomly selected for the study. A two-stage cluster design vector sampling, developed and validated at a sub-district level, was implemented in 30 randomly selected clusters in the EU. Female Culex quinquefasciatus were collected placing gravid traps overnight (1800-0600 hrs) inside the premises of systematically selected households. Pools of 20-25 blood-fed, semi-gravid and gravid Cx. quinquefasciatus were subjected to real-time quantitative PCR (polymerase chain reaction) assay for detecting Wuchereria bancrofti DNA. Pool infection rate (% of pools positive for W. bancrofti DNA), and the estimated prevalence of W. bancrofti DNA in mosquitoes and its 95% confidence interval were calculated. Additionally, in these 30 clusters, microfilaria (Mf) survey among individuals >5 years old was carried out. School-based TAS was conducted using Immunochromatographic Card Test (ICT) in the EU. Prepared itemized cost-menu for different cost components of MX survey and TAS were estimated and compared. RESULTS: MX survey showed that only 11 (3.1%) of the 358 pools (8850 Cx.quinquefasciatus females), collected from 30 clusters, were found positive for W. bancrofti DNA. The estimated vector infection rate was 0.13% (95% CI: 0.07-0.22%), below the provisional threshold (0.25%) for transmission interruption. Of 1578 children tested in the TAS, only four (0.25%) were positive for filarial antigenemia, and it is well below the critical cut-off (18 positives) for stopping MDA. Among 9804 persons tested in the 30 clusters, only four were found positive for Mf (0.04%; 95% CI: 0.01-0.1%). The Mf-prevalence was <1% threshold for transmission interruption in humans. The estimated costs for TAS and MX per EU were $14,104 USD and $14,259 USD respectively. CONCLUSIONS: The result of MX protocol was in good agreement with that of TAS, providing evidence to recommend MX as a complementary tool to TAS to decide on stopping MDA. MX can also be a potential surveillance tool for post-MDA and post-validation phases as it could detect sites with residual infection and risk of resurgence of transmission. MX is economically feasible as its cost is slightly higher than that of TAS.


Assuntos
Culex/parasitologia , DNA de Helmintos/análise , Filariose Linfática/prevenção & controle , Administração Massiva de Medicamentos , Wuchereria bancrofti/isolamento & purificação , Animais , Criança , Filariose Linfática/epidemiologia , Feminino , Humanos , Índia/epidemiologia , Mosquitos Vetores/parasitologia , Prevalência , Reação em Cadeia da Polimerase em Tempo Real , Wuchereria bancrofti/genética
6.
Rev Soc Bras Med Trop ; 52: e20190308, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31800921

RESUMO

Malaria, a mosquito-borne infectious disease, is considered a significant global health burden. Climate changes or different weather conditions may impact infectious diseases, specifically those transmitted by insect vectors and contaminated water. Based on the current predictions for climate change associated with the increase in carbon dioxide concentrations in the atmosphere and the increase in atmospheric temperature, the Intergovernmental Panel on Climate Change predicts that in 2050, malaria may threaten some previously unexposed areas worldwide and cause a 50% higher probability of malaria cases. Climate-based distribution models of malaria depict an increase in the geographic distribution of the disease as global environmental temperatures and conditions worsen. Researchers have studied the influence of changes in climate on the prevalence of malaria using different mathematical models that consider different variables and predict the conditions for malaria distribution. In this context, we conducted a mini-review to elucidate the important aspects described in the literature on the influence of climate change in the distribution and transmission of malaria. It is important to develop possible risk management strategies and enhance the surveillance system enhanced even in currently malaria-free areas predicted to experience malaria in the future.


Assuntos
Anopheles/parasitologia , Mudança Climática , Malária/transmissão , Mosquitos Vetores/parasitologia , Animais , Modelos Biológicos , Dinâmica Populacional
7.
Pestic Biochem Physiol ; 161: 61-67, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31685198

RESUMO

Extensive use of pyrethroids for malaria control in Africa has led to widespread pyrethroid resistance in the two major African vectors of malaria An. gambiae and An. funestus. This is often associated with constitutively elevated levels of cytochrome P450s involved with pyrethroid metabolism and detoxification. P450s have the capacity to metabolise diverse substrates, which raises concerns about their potential to cause cross-resistance. A bank of seven recombinant P450s from An. gambiae (CYPs 6M2, 6P2, 6P3, 6P4, 6P5, 9J5) and An. funestus (CYP6P9a) commonly associated with pyrethroid resistance were screened against twelve insecticides representing the five major classes of insecticides recommended by WHO for malaria control; permethrin, etofenprox and bifenthrin (type I pyrethroids), deltamethrin, lambda cyhalothrin and cypermethrin (type II pyrethroids), DDT (organochlorine), bendiocarb (carbamate), malathion, pirimiphos methyl and fenitrothion (organophosphates) and pyriproxyfen (juvenile hormone analogue). DDT was not metabolised by the P450 panel, while bendiocarb was only metabolised by CYP6P3. Pyrethroids and pyriproxyfen were largely susceptible to metabolism by the P450 panel, as were organophosphates, which are activated by P450s. Primiphos-methyl is increasingly used for malaria control. Examination of the pirimiphos-methyl metabolites generated by CYP6P3 revealed both the active pirimiphos-methyl-oxon form and the inactive oxidative cleavage product 2-diethylamino-6-hydroxy-4-methylpyrimidine. The inhibition profile of CYPs 6M2, 6P2, 6P3, 6P9a and 9J5 was also examined using diethoxyfluorescein (DEF) as the probe substrate. Bendiocarb was the weakest inhibitor with IC50 > 100 µM across the P450 panel, while CYP6M2 showed strongest inhibition by malathion (IC50 0.7 µM). The results suggest that P450s present at elevated levels in two major Anopheline vectors of malaria in Africa have the capacity to metabolise a diverse range of pyrethroid and organophosphate insecticides as well as pyriproxyfen that could impact vector control.


Assuntos
Anopheles/efeitos dos fármacos , Anopheles/enzimologia , Sistema Enzimático do Citocromo P-450/metabolismo , Resistência a Inseticidas , Malária/transmissão , Mosquitos Vetores/efeitos dos fármacos , Piretrinas/farmacologia , Animais , Anopheles/classificação , Controle de Mosquitos/métodos , Mosquitos Vetores/parasitologia , Compostos Organotiofosforados/farmacologia , Especificidade da Espécie
8.
PLoS Genet ; 15(10): e1008453, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31609965

RESUMO

Determining the genetic basis of fitness is central to understanding evolution and transmission of microbial pathogens. In human malaria parasites (Plasmodium falciparum), most experimental work on fitness has focused on asexual blood stage parasites, because this stage can be easily cultured, although the transmission of malaria requires both female Anopheles mosquitoes and vertebrate hosts. We explore a powerful approach to identify the genetic determinants of parasite fitness across both invertebrate and vertebrate life-cycle stages of P. falciparum. This combines experimental genetic crosses using humanized mice, with selective whole genome amplification and pooled sequencing to determine genome-wide allele frequencies and identify genomic regions under selection across multiple lifecycle stages. We applied this approach to genetic crosses between artemisinin resistant (ART-R, kelch13-C580Y) and ART-sensitive (ART-S, kelch13-WT) parasites, recently isolated from Southeast Asian patients. Two striking results emerge: we observed (i) a strong genome-wide skew (>80%) towards alleles from the ART-R parent in the mosquito stage, that dropped to ~50% in the blood stage as selfed ART-R parasites were selected against; and (ii) repeatable allele specific skews in blood stage parasites with particularly strong selection (selection coefficient (s) ≤ 0.18/asexual cycle) against alleles from the ART-R parent at loci on chromosome 12 containing MRP2 and chromosome 14 containing ARPS10. This approach robustly identifies selected loci and has strong potential for identifying parasite genes that interact with the mosquito vector or compensatory loci involved in drug resistance.


Assuntos
Interações Hospedeiro-Parasita/genética , Estágios do Ciclo de Vida/genética , Malária Falciparum/parasitologia , Plasmodium falciparum/genética , Proteínas de Protozoários/genética , Animais , Anopheles/parasitologia , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Artemisininas/farmacologia , Artemisininas/uso terapêutico , Mapeamento Cromossômico , Modelos Animais de Doenças , Resistência a Medicamentos/genética , Feminino , Frequência do Gene , Loci Gênicos , Humanos , Malária Falciparum/tratamento farmacológico , Masculino , Camundongos , Mosquitos Vetores/parasitologia , Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/crescimento & desenvolvimento , Polimorfismo de Nucleotídeo Único , Proteínas Ribossômicas/genética , Seleção Genética , Quimeras de Transplante
9.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 31(4): 414-417, 2019 Sep 26.
Artigo em Chinês | MEDLINE | ID: mdl-31612678

RESUMO

OBJECTIVE: To explore the spatial-temporal distribution of malaria in Jiangxi Province from 1950 to 2017, so as to provide scientific evidence for developing the malaria elimination strategy. METHODS: The epidemic situation of malaria, demographic data, historical species of malaria parasites and transmission vectors were collected from each county of Jiangxi Province from 1950 to 2017 to create a geographic information system database of malaria in Jiangxi Province. The software ArcGIS 10.3 was used to analyze the incidence of malaria and display the spatial-temporal distribution of malaria in Jiangxi Province, so as to explore the spatial-temporal patterns of malaria in the province. RESULTS: From 1950 to 2017, the prevalence of malaria was classified into 3 stages in Jiangxi Province, including the peak period (from 1950 to 1975), the continuous decline period (from 1976 to 1997), and the low-level fluctuation period (from 1998 to 2017). During the period from 1950 through 2017, the incidence of malaria declined, the epidemic area of malaria shrank, and the intensity of malaria transmission gradually reduced to no local infections in Jiangxi Province. The spatial distribution of epidemic areas of malaria shifted from southern mountainous areas to northern plain areas, and finally aggregated, retained and disappeared in plain areas. The species of malaria parasites shifted from a co-endemic area for Plasmodium vivax, P. falciparum and P. malariae to a single endemic area for P. vivax, and finally a co-endemic area for imported P. vivax, P. falciparum, P. malariae and P. ovale. The transmission vectors shifted from multiple vectors of Anopheles sinensis, An. minimus, An. anthropophagus and others to a single vector of An. sinensis. CONCLUSIONS: There are no local malaria cases for successive 6 years since 2012, and the transmission of malaria has been interrupted in Jiangxi Province, in which the criteria for malaria elimination have been achieved. However, the risk of malaria transmission secondary to imported malaria will emerge in Jiangxi Province for a long period of time.


Assuntos
Anopheles , Malária , Animais , China/epidemiologia , Erradicação de Doenças , Malária/epidemiologia , Malária/parasitologia , Malária/transmissão , Mosquitos Vetores/parasitologia , Plasmodium/fisiologia , Prevalência , Fatores de Risco
10.
BMC Res Notes ; 12(1): 645, 2019 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-31585549

RESUMO

OBJECTIVE: We investigated this outbreak to describe the magnitude and associated risk factors due to the malaria outbreak in Tanquae Abergelle district, Tigray, Ethiopia, in 2017. RESULT: Case fatality rate of this study was zero. Among the 62 cases and 124 controls, the presence of mosquito breeding sites [OR = 6.56 CI (2.09-20.58) P value = 0.001], sleeping outside a home [OR = 5.06 CI (1.75-14.61) P-value = 0.003] and having unscreened window [OR = 14.89 CI (1.87-118.25) P-value = 0.011] were associated with illness in multivariate analysis.


Assuntos
Surtos de Doenças , Malária Falciparum/epidemiologia , Malária Vivax/epidemiologia , Mosquiteiros/estatística & dados numéricos , Adolescente , Adulto , Animais , Anopheles/parasitologia , Estudos de Casos e Controles , Criança , Pré-Escolar , Etiópia/epidemiologia , Feminino , Humanos , Lactente , Recém-Nascido , Malária Falciparum/parasitologia , Malária Falciparum/transmissão , Malária Vivax/parasitologia , Malária Vivax/transmissão , Masculino , Pessoa de Meia-Idade , Mosquitos Vetores/parasitologia , Plasmodium falciparum/patogenicidade , Plasmodium vivax/patogenicidade , Fatores de Risco , Sono
11.
Parasit Vectors ; 12(1): 501, 2019 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-31655608

RESUMO

Malaria still has a devastating impact on public health and welfare in Cameroon. Despite the increasing number of studies conducted on disease prevalence, transmission patterns or treatment, there are to date, not enough studies summarising findings from previous works in order to identify gaps in knowledge and areas of interest where further evidence is needed to drive malaria elimination efforts. The present study seeks to address these gaps by providing a review of studies conducted so far on malaria in Cameroon since the 1940s to date. Over 250 scientific publications were consulted for this purpose. Although there has been increased scale-up of vector control interventions which significantly reduced the morbidity and mortality to malaria across the country from a prevalence of 41% of the population reporting at least one malaria case episode in 2000 to a prevalence of 24% in 2017, the situation is not yet under control. There is a high variability in disease endemicity between epidemiological settings with prevalence of Plasmodium parasitaemia varying from 7 to 85% in children aged 6 months to 15 years after long-lasting insecticidal nets (LLINs) scale-up. Four species of Plasmodium have been recorded across the country: Plasmodium falciparum, P. malariae, P. ovale and P. vivax. Several primate-infecting Plasmodium spp. are also circulating in Cameroon. A decline of artemisinin-based combinations therapeutic efficacy from 97% in 2006 to 90% in 2016 have been reported. Several mutations in the P. falciparum chloroquine resistance (Pfcrt) and P. falciparum multidrug resistance 1 (Pfmdr1) genes conferring resistance to either 4-amino-quinoleine, mefloquine, halofanthrine and quinine have been documented. Mutations in the Pfdhfr and Pfdhps genes involved in sulfadoxine-pyrimethamine are also on the rise. No mutation associated with artemisinin resistance has been recorded. Sixteen anopheline species contribute to malaria parasite transmission with six recognized as major vectors: An. gambiae, An. coluzzii, An. arabiensis, An. funestus, An. nili and An. moucheti. Studies conducted so far, indicated rapid expansion of DDT, pyrethroid and carbamate resistance in An. gambiae, An. coluzzii, An. arabiensis and An. funestus threatening the performance of LLINs. This review highlights the complex situation of malaria in Cameroon and the need to urgently implement and reinforce integrated control strategies in different epidemiological settings, as part of the substantial efforts to consolidate gains and advance towards malaria elimination in the country.


Assuntos
Malária/epidemiologia , Malária/prevenção & controle , Animais , Anopheles/classificação , Anopheles/genética , Anopheles/parasitologia , Camarões/epidemiologia , Humanos , Resistência a Inseticidas , Malária/terapia , Malária/transmissão , Controle de Mosquitos/tendências , Mosquitos Vetores/classificação , Mosquitos Vetores/genética , Mosquitos Vetores/parasitologia , Plasmodium/classificação , Plasmodium/patogenicidade , Prevalência , Saúde Pública
12.
Nat Commun ; 10(1): 3939, 2019 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-31477710

RESUMO

Heterogeneity in transmission is a challenge for infectious disease dynamics and control. An 80-20 "Pareto" rule has been proposed to describe this heterogeneity whereby 80% of transmission is accounted for by 20% of individuals, herein called super-spreaders. It is unclear, however, whether super-spreading can be attributed to certain individuals or whether it is an unpredictable and unavoidable feature of epidemics. Here, we investigate heterogeneous malaria transmission at three sites in Uganda and find that super-spreading is negatively correlated with overall malaria transmission intensity. Mosquito biting among humans is 90-10 at the lowest transmission intensities declining to less than 70-30 at the highest intensities. For super-spreaders, biting ranges from 70-30 down to 60-40. The difference, approximately half the total variance, is due to environmental stochasticity. Super-spreading is thus partly due to super-spreaders, but modest gains are expected from targeting super-spreaders.


Assuntos
Algoritmos , Doenças Transmissíveis/transmissão , Malária/transmissão , Modelos Teóricos , Animais , Anopheles/parasitologia , Anopheles/fisiologia , Doenças Transmissíveis/epidemiologia , Doenças Transmissíveis/parasitologia , Humanos , Malária/epidemiologia , Malária/parasitologia , Mosquitos Vetores/parasitologia , Mosquitos Vetores/fisiologia , Plasmodium/fisiologia , Processos Estocásticos , Uganda/epidemiologia
13.
New Microbiol ; 42(4): 234-236, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31524944

RESUMO

Human dirofilariosis is a zoonosis caused by different Dirofilaria species: D. repens, D. immitis, D. tenuis and D. ursi, thin nematodes belonging to the Onchocercidae family, whose larval stages are generally found in the natural (felines and canids) or accidental (human) definitive host. In Europe, human infection is rare, even in areas considered endemic such as Spain or Italy. In this paper we describe the case of an 82-year-old woman living in Modugno (Bari municipality), who came to our observation for a subcutaneous nodule on her right thigh that had appeared in the previous two weeks and gradually became necrotic. The woman lived in an apartment with a dog. An adult worm, white, thin, about 140 mm long, came out of the necrotic area spontaneously. After microscopic examination, the worm was identified as D. repens. In Apulia, a South-Italy region, human dirofilariosis is a rare disease and since 1885 only 11 cases have been reported. In recent years we have witnessed an increase in the number of diseases transmitted by vectors at all latitudes, and in our region an increase in the Aedes albopticus population has been reported, so it is reasonable to expect an increase in dirofilariosis cases in humans.


Assuntos
Dirofilaria repens , Dirofilariose , Aedes/fisiologia , Idoso de 80 Anos ou mais , Animais , Dirofilariose/diagnóstico , Dirofilariose/parasitologia , Feminino , Humanos , Itália , Mosquitos Vetores/parasitologia , Mosquitos Vetores/fisiologia
14.
Acta Trop ; 199: 105121, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31400299

RESUMO

Lymphatic filariasis (LF) has been known in Egypt since ancient times. By 1930s it was recognized to be a major public health problem in the Nile Delta, and to be caused by Wuchereria bancrofti and transmitted by Culex pipiens. Remarkably, as a result of widespread DEC treatment and intensive vector control by the Ministry of Health and Population (MoHP), the infection rate of LF declined in the 1960s. However, relaxation of these efforts resulted in resurgence of filariasis in the 1980s and 1990s. In 2000, Egypt was among the first countries to join the WHO global efforts to eliminate LF as a public health problem by initiating a national LF elimination programme (NLFEP). This article reviews the history of LF control activities and summarizes the NLFEP extensive interventions to eliminate LF in Egypt. Based on MoHP data, mass drug administration (MDA) with DEC and ALB was started in 2000 in 161 implementation units (IUs). Additional IUs were included in subsequent MDA rounds, with the last IU included in 2007. MDA stopping surveys were conducted based on WHO guidelines (2005; 2011). Information about the presence of those suffering from lymphoedema/elephantiasis and hydrocele patients was collected, and care provided to those needing care in five rural health units (RHU) by primary health care system providers who were given training on LF morbidity management and disability prevention (MMDP). The NLFEP made excellent progress due to strong collaboration between different ministries, through intensive training and supervision, and the use of advocacy for mobilization of endemic communities. The epidemiological coverage for all MDA rounds was effectively ≥80%. Antigenemia levels found in schoolchildren during transmission assessment surveys (TAS) in 166 IUs approximately 10 years after stopping MDA was 0%. In 2017, TAS conducted in additional 29 IUs indicated 0.1% antigenemia and 0% microfilaremia. In 2015, the registration of chronic LF patients was updated to 1472 lymphoedema and 18 hydrocele patients. Lymphoedema patients were trained on self-management, and hydrocele patients were referred to local General Hospitals for surgery. Thus, after over a decade of sustained effort, Egypt met the WHO criteria for successful elimination of LF as a public health problem. In December 2017, WHO validated Egypt as the first country in the Eastern Mediterranean Region to successfully achieve elimination.


Assuntos
Culex/parasitologia , Filariose Linfática/prevenção & controle , Filaricidas/administração & dosagem , Mosquitos Vetores/parasitologia , Wuchereria bancrofti , Animais , Criança , Egito/epidemiologia , Filariose Linfática/epidemiologia , Filariose Linfática/transmissão , Filaricidas/farmacologia , Filaricidas/uso terapêutico , Humanos , Masculino , Administração Massiva de Medicamentos , Saúde Pública , Saúde da População Rural , Inquéritos e Questionários , Wuchereria bancrofti/efeitos dos fármacos
15.
Malar J ; 18(1): 276, 2019 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-31426810

RESUMO

BACKGROUND: Parasites from the genus Plasmodium, the aetiological agent of malaria in humans, can also infect non-human primates (NHP), increasing the potential risk of zoonotic transmission with its associated global public health concerns. In Colombia, there are no recent studies on Plasmodium spp. infecting free-ranging NHP. Thus, this study aimed to determine the diversity of Plasmodium species circulating in fragmented forests in central Colombia, both in Anopheles mosquitoes and in the four sympatric NHP in the region (Ateles hybridus, Cebus versicolor, Alouatta seniculus and Aotus griseimembra), in order to evaluate the risk of infection to humans associated with the presence of sylvatic hosts and vectors infected with Plasmodium spp. METHODS: Overall, there were collected 166 fecal samples and 25 blood samples from NHP, and 442 individuals of Anopheles spp. DNA extraction, nested PCR using mitochondrial (cox3 gene) and ribosomal (18S rDNA) primers, electrophoresis and sequencing were conducted in order to identify Plasmodium spp. from the samples. RESULTS: Plasmodium falciparum was detected in two fecal samples of Alouatta seniculus, while Plasmodium vivax/simium infected Ateles hybridus, Cebus versicolor and Alouatta seniculus. Co-infections with P. vivax/simium and Plasmodium malariae/brasilianum were found in three individuals. The highest prevalence from blood samples was found for Plasmodium malariae/brasilianum in two Alouatta seniculus while Plasmodium vivax/simium was most prevalent in fecal samples, infecting four individuals of Alouatta seniculus. Seven Anopheles species were identified in the study site: Anopheles (Anopheles) punctimacula, Anopheles (An.) malefactor, Anopheles (Nyssorhynchus) oswaldoi, Anopheles (Nys.) triannulatus, Anopheles (An.) neomaculipalpus, Anopheles (Nys.) braziliensis and Anopheles (Nys.) nuneztovari. Infection with P. vivax/simium was found in An. nuneztovari, An. neomaculipalpus, and An. triannulatus. Furthermore, An. oswaldoi and An. triannulatus were found infected with P. malariae/brasilianum. The effect of fragmentation and distance to the nearest town measured in five forests with different degrees of fragmentation was not statistically significant on the prevalence of Plasmodium in NHP, but forest fragmentation did have an effect on the Minimum Infection Rate (MIR) in Anopheles mosquitoes. CONCLUSIONS: The presence of Plasmodium spp. in NHP and Anopheles spp. in fragmented forests in Colombia has important epidemiological implications in the human-NHP interface and the associated risk of malaria transmission.


Assuntos
Anopheles/parasitologia , Malária/veterinária , Doenças dos Macacos/epidemiologia , Mosquitos Vetores/parasitologia , Plasmodium/isolamento & purificação , Platirrinos , Animais , Colômbia/epidemiologia , Meio Ambiente , Florestas , Malária/epidemiologia , Malária/parasitologia , Doenças dos Macacos/parasitologia , Prevalência
16.
Malar J ; 18(1): 287, 2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31455343

RESUMO

BACKGROUND: The human infectious reservoir for malaria consists of individuals capable of infecting mosquitoes. Oocyst prevalence and density are typical indicators of human infectivity to mosquitoes. However, identification of oocysts is challenging, particularly in areas of low malaria transmission intensity where few individuals may infect mosquitoes, and infected mosquitoes tend to have few oocysts. Here, features that differentiate oocysts from other oocyst-like in mosquito midguts are explained and illustrated. In addition, the establishment and maintenance of infrastructure to perform malaria transmission experiments is described. This work may support other initiatives to set up membrane feeding infrastructure and guide oocyst detection in low transmission settings. METHODS: In 2014, an insectary was developed and equipped in Tororo district, Uganda. A colony of Anopheles gambiae s.s. mosquitoes (Kisumu strain) was initiated to support infectivity experiments from participants enrolled in a large cohort study. Venous blood drawn from participants who were naturally infected with malaria parasites was used for membrane feeding assays, using 60-80 mosquitoes per experiment. Approximately 9-10 days after feeding, mosquitoes were dissected, and midguts were stained in mercurochrome and examined by light microscopy for Plasmodium falciparum oocysts and similar structures. In supportive experiments, different staining procedures were compared using in vitro cultured parasites. RESULTS: A stable colony of the Kisumu strain of An. gambiae s.s. was achieved, producing 5000-10,000 adult mosquitoes on a weekly basis. Challenges due to temperature fluctuations, mosquito pathogens and pests were successfully overcome. Oocysts were characterized by: presence of malaria pigment, clearly defined edge, round shape within the mosquito midgut or on the peripheral tissue and always attached to the epithelium. The main distinguishing feature between artifacts and mature oocysts was the presence of defined pigment within the oocysts. CONCLUSIONS: Oocysts may be mistaken for other structures in mosquito midguts. Distinguishing real oocysts from oocyst-like structures may be challenging for inexperienced microscopists due to overlapping features. The characteristics and guidelines outlined here support identification of oocysts and reliable detection at low oocyst densities. Practical advice on sustaining a healthy mosquito colony for feeding experiments is provided. Following the reported optimization, the established infrastructure in Tororo allows assessments of infectivity of naturally infected parasite carriers.


Assuntos
Anopheles/parasitologia , Mosquitos Vetores/parasitologia , Oocistos/isolamento & purificação , Plasmodium falciparum/isolamento & purificação , Animais , Feminino , Humanos , Oocistos/citologia , Oocistos/crescimento & desenvolvimento , Plasmodium falciparum/citologia , Plasmodium falciparum/crescimento & desenvolvimento , Uganda
17.
Parasit Vectors ; 12(1): 386, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31370863

RESUMO

BACKGROUND: Anopheles albimanus is a malaria vector in Central America, northern South America and the Caribbean. Although a public health threat, An. albimanus precopulatory mating behaviors are unknown. Acoustics play important roles in mosquito communication, where flight tones allow males to detect and attract potential mates. The importance of sound in precopulatory interactions has been demonstrated in Toxorhynchites brevipalpis, Aedes aegypti, Culex quinquefasciatus and Anopheles gambiae; convergence in a shared harmonic of the wing beat frequency (WBF) during courtship is thought to increase the chance of copulation. To our knowledge, An. albimanus precopulatory acoustic behaviors have not been described to date. Here, we characterized An. albimanus (i) male and female flight tones; (ii) male-female precopulatory acoustic interactions under tethered and free flight conditions; and (iii) male-male acoustic interactions during free flight. RESULTS: We found significant increases in the WBFs of both sexes in free flight compared to when tethered. We observed harmonic convergence between 79% of tethered couples. In free flight, we identified a female-specific behavior that predicts mate rejection during male mating attempts: females increase their WBFs significantly faster during mate rejection compared to a successful copulation. This behavior consistently occurred during mate rejection regardless of prior mating attempts (from the same or differing male). During group flight, males of An. albimanus displayed two distinct flying behaviors: random flight and a swarm-like, patterned flight, each associated with distinct acoustic characteristics. In the transition from random to patterned flight, males converged their WBFs and significantly decreased flight area, male-male proximity and the periodicity of their trajectories. CONCLUSIONS: We show that tethering of An. albimanus results in major acoustic differences compared to free flight. We identify a female-specific behavior that predicts mate rejection during male mating attempts in this species and show that male groups in free flight display distinct flying patterns with unique audio and visual characteristics. This study shows that An. albimanus display acoustic features identified in other mosquito species, further suggesting that acoustic interactions provide worthwhile targets for mosquito intervention strategies. Our results provide compelling evidence for swarming in this species and suggests that acoustic signaling is important for this behavior.


Assuntos
Comunicação Animal , Anopheles/fisiologia , Mosquitos Vetores/fisiologia , Comportamento Sexual Animal , Som , Animais , Anopheles/parasitologia , Feminino , Malária/transmissão , Masculino , Mosquitos Vetores/parasitologia
18.
Parasit Vectors ; 12(1): 385, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31370906

RESUMO

BACKGROUND: Population density, dispersion patterns, flight distances, and survival rate of vector mosquitoes are all contributors to vectorial capacity that may be estimated in a single experimental method: mark-release-recapture (MRR). In this study, these key parameters were measured for mosquito populations in Karama, West Sulawesi, Indonesia. METHODS: Two mark-release-recapture (MRR) experiments were carried out in Karama village to characterize seasonality differences, if any: wet season (December 2013, MRR1) and dry season (May 2014, MRR2). For both experiments, mosquitoes were marked according to release site/date and were released on four consecutive nights. Four sampling methodologies were utilized to enable recapture: human landing catches (HLCs), kelambu traps and barrier screens. RESULTS: 98.7% of all catches were molecularly confirmed as Anopheles barbirostris. During the wet season, An. barbirostris demonstrated no preference toward endophagy. In the dry season, An. barbirostris demonstrated an endophagic preference. The duration of the feeding cycle for An. barbirostris was determined to be 5 days during the wet season and 3.7 days during the dry season, though an anomaly likely caused the wet season feeding cycle to be overestimated. The largest percentages of recaptured mosquitoes were collected in a single site during both seasons. The only significant relationship with mosquito dispersal was site of release and recapture. Finally, dispersal rates of An. barbirostris frequently ranged up to 800 m (the maximum measurable distance in this study) within a single day of release. CONCLUSIONS: This study estimated key vector parameters for An. barbirostris an understudied species complex, in Karama, West Sulawesi, Indonesia. Despite the length of the feeding cycle, the high indoor biting rates demonstrated by An. barbirostris in Karama suggest that the use of IRSs and LLINs, especially during the dry season, would have a substantial impact on the panmictic An. barbirostris population.


Assuntos
Anopheles/fisiologia , Comportamento Alimentar , Mosquitos Vetores/fisiologia , Análise Espaço-Temporal , Animais , Anopheles/parasitologia , Feminino , Indonésia , Malária/transmissão , Mosquitos Vetores/parasitologia , Densidade Demográfica , Estações do Ano
19.
Malar J ; 18(1): 296, 2019 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-31464619

RESUMO

BACKGROUND: Most malaria vector control programmes rely on indoor residual spraying of insecticides and insecticide-treated bed nets. This is effective against vector species that feed indoors at night and rest inside the house afterwards. In Central America, malaria vectors have different behaviours and are typically exophagic (i.e., bite outdoors), exophilic (i.e., remain outdoors after feeding), and zoophagic (i.e., as likely to feed on non-humans as humans). Thus, malaria elimination in Central America may require additional tactics. This pilot study investigated whether commercially-available products used to treat livestock for ticks could also be used to kill and/or sterilize zoophagic malaria vectors that feed on treated cattle in Belize. METHODS: Cattle were treated with either a pour-on formulation of 1% fipronil (3 heifers) or injection of 1% ivemectin (1 heifer). Control heifers (n = 2) were left untreated. Field-collected Anopheles albimanus contained in screen-top cages were strapped onto cattle at 2, 5, 7, and 14 days after treatment. Mosquito mortality was monitored once a day for 4 successive days. Surviving mosquitoes were dissected to assess blood meal digestion and ovarian development. RESULTS: A total of 1078 female An. albimanus mosquitoes were fed and monitored for mortality. Both fipronil and ivermectin significantly reduced survivorship of An. albimanus for up to 7 days after treatment. By 14 days, efficacy had declined. The ivermectin treatment completely lost its effectiveness and even though the fipronil-treated heifers were still killing significantly more mosquitoes than the untreated heifers, the amount of mosquito killing had diminished greatly. Both treatments significantly reduced ovary development in mosquitoes fed on treated cattle for the duration of the 2-week trial. CONCLUSIONS: Treatment of cattle in northern Belize with topical fipronil and injectable ivermectin had significant lethal and sublethal effects on wild An. albimanus females. These results suggest that efforts towards eliminating residual transmission of malaria by zoophagic vectors in Central America may benefit by the judicious, targeted treatment of livestock with mosquitocidal compounds, such as fipronil or ivermectin.


Assuntos
Inseticidas/administração & dosagem , Ivermectina/administração & dosagem , Controle de Mosquitos/métodos , Ovário/efeitos dos fármacos , Pirazóis/administração & dosagem , Administração Tópica , Animais , Belize , Bovinos , Comportamento Alimentar , Feminino , Injeções Intramusculares/efeitos adversos , Malária/prevenção & controle , Masculino , Mosquitos Vetores/parasitologia , Projetos Piloto
20.
PLoS Pathog ; 15(7): e1007973, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31348803

RESUMO

The essential and distinct functions of Protein Phosphatase type 1 (PP1) catalytic subunit in eukaryotes are exclusively achieved through its interaction with a myriad of regulatory partners. In this work, we report the molecular and functional characterization of Gametocyte EXported Protein 15 (GEXP15), a Plasmodium specific protein, as a regulator of PP1. In vitro interaction studies demonstrated that GEXP15 physically interacts with PP1 through the RVxF binding motif in P. berghei. Functional assays showed that GEXP15 was able to increase PP1 activity and the mutation of the RVxF motif completely abolished this regulation. Immunoprecipitation assays of tagged GEXP15 or PP1 in P. berghei followed by immunoblot or mass spectrometry analyses confirmed their interaction and showed that they are present both in schizont and gametocyte stages in shared protein complexes involved in the spliceosome and proteasome pathways and known to play essential role in parasite development. Phenotypic analysis of viable GEXP15 deficient P. berghei blood parasites showed that they were unable to develop lethal infection in BALB/c mice or to establish experimental cerebral malaria in C57BL/6 mice. Further, although deficient parasites produced gametocytes they did not produce any oocysts/sporozoites indicating a high fitness cost in the mosquito. Global proteomic and phosphoproteomic analyses of GEXP15 deficient schizonts revealed a profound defect with a significant decrease in the abundance and an impact on phosphorylation status of proteins involved in regulation of gene expression or invasion. Moreover, depletion of GEXP15 seemed to impact mainly the abundance of some specific proteins of female gametocytes. Our study provides the first insight into the contribution of a PP1 regulator to Plasmodium virulence and suggests that GEXP15 affects both the asexual and sexual life cycle.


Assuntos
Plasmodium berghei/crescimento & desenvolvimento , Plasmodium berghei/fisiologia , Proteína Fosfatase 1/fisiologia , Proteínas de Protozoários/fisiologia , Animais , Anopheles/parasitologia , Eritrócitos/parasitologia , Feminino , Genes de Protozoários , Interações Hospedeiro-Parasita/genética , Interações Hospedeiro-Parasita/fisiologia , Humanos , Malária/parasitologia , Malária/transmissão , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Mosquitos Vetores/parasitologia , Plasmodium berghei/genética , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Proteína Fosfatase 1/química , Proteína Fosfatase 1/genética , Proteômica , Proteínas de Protozoários/química , Proteínas de Protozoários/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
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