RESUMO
Cross-border human population movement contributes to malaria transmission in border regions, impeding national elimination. However, its impact in low-to-moderate transmission settings is not well characterized. This community-based study in Mutasa District, Zimbabwe, estimated the association of parasite prevalence with self-reported overnight travel to Mozambique and household distance to the border from 2012-2020. A fully adjusted Poisson regression model with robust variance estimation was fit using active surveillance data. The population attributable fraction of parasite prevalence from overnight travel was also estimated. The relative risk of testing positive for malaria by rapid diagnostic test declined 14% (prevalence ratio [PR] = 0.86, 95% CI = 0.81-0.92) per kilometer from the border up to 12 km away. Travel to Mozambique was associated with a 157% increased risk (PR = 2.57, 95% CI = 1.38-4.78), although only 5.8% of cases were attributable to overnight travel (95% CI = -1.1% to 12.7%), reflecting infrequent overnight trips (1.3% of visits). This study suggests that transmission in eastern Zimbabwe is driven by increasingly conducive social or environmental conditions approaching the border and low levels of importation from overnight travel. Although day trips to Mozambique during peak biting hours were not assessed, the contribution of such trips to ongoing transmission may be significant. Future malaria control efforts should prioritize high coverage of existing interventions and continued support for community health workers and health facilities at the border, which provide free case management.
Assuntos
Parasitemia , Viagem , Humanos , Zimbábue/epidemiologia , Moçambique/epidemiologia , Masculino , Feminino , Adulto , Parasitemia/epidemiologia , Parasitemia/transmissão , Adolescente , Adulto Jovem , Criança , Prevalência , Malária Falciparum/epidemiologia , Malária Falciparum/transmissão , Características da Família , Pré-Escolar , Pessoa de Meia-Idade , Malária/transmissão , Malária/epidemiologia , Plasmodium falciparum/isolamento & purificação , LactenteRESUMO
Malaria elimination means cessation of parasite transmission. At present, the declining malaria incidence in many countries has made elimination a feasible goal. Transmission control has thus been placed at the center of the national malaria control programs. The efficient transmission of Plasmodium vivax from humans to mosquitoes is a key factor that helps perpetuate malaria in endemic areas. A better understanding of transmission is crucial to the success of elimination efforts. Biological delineation of the parasite transmission process is important for identifying and prioritizing new targets of intervention. Identification of the infectious parasite reservoir in the community is key to devising an effective elimination strategy. Here we describe the fundamental characteristics of P. vivax gametocytes - the dynamics of their production, longevity, and the relationship with the total parasitemia - as well as recent advances in the molecular understanding of parasite sexual development. In relation to malaria elimination, factors influencing the human infectivity and the current evidence for a role of asymptomatic carriers in transmission are presented.
Assuntos
Malária Vivax/transmissão , Plasmodium vivax/fisiologia , Animais , Anopheles/parasitologia , Feminino , Humanos , Malária Vivax/imunologia , Malária Vivax/parasitologia , Masculino , Mosquitos Vetores/parasitologia , Parasitemia/parasitologia , Parasitemia/transmissãoRESUMO
Tororo, a district in Uganda with historically high malaria transmission intensity, has recently scaled up control interventions, including universal long-lasting insecticidal net distribution in 2013 and 2017, and sustained indoor residual spraying (IRS) of insecticide since December 2014. We describe the burden of malaria in Tororo 5 years following the initiation of IRS. We followed a cohort of 531 participants from 80 randomly selected households in Nagongera subcounty, Tororo district, from October 2017 to October 2019. Mosquitoes were collected every 2 weeks using CDC light traps in all rooms where participants slept, symptomatic malaria was identified by passive surveillance, and microscopic and submicroscopic parasitemia were measured every 4 weeks using active surveillance. Over the 2 years of follow-up, 15,780 female anopheline mosquitos were collected, the majority (98.0%) of which were Anopheles arabiensis. The daily human biting rate was 2.07, and the annual entomological inoculation rate was 0.43 infective bites/person/year. Only 38 episodes of malaria were diagnosed (incidence 0.04 episodes/person/year), and there were no cases of severe malaria or malarial deaths. The prevalence of microscopic parasitemia was 1.9%, and the combined prevalence of microscopic and submicroscopic parasitemia was 10.4%, each highest in children aged 5-15 years (3.3% and 14.0%, respectively). After 5 years of intensive vector control measures in Tororo, the burden of malaria was reduced to very low transmission levels. However, a significant proportion of the population remained parasitemic, primarily school-aged children with submicroscopic parasitemia, providing a potential reservoir for malaria transmission.
Assuntos
Anopheles/parasitologia , Inseticidas/uso terapêutico , Malária/epidemiologia , Controle de Mosquitos , Mosquitos Vetores/parasitologia , Adolescente , Animais , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Humanos , Incidência , Malária/parasitologia , Malária/prevenção & controle , Malária/transmissão , Masculino , Parasitemia/epidemiologia , Parasitemia/parasitologia , Parasitemia/transmissão , Prevalência , Uganda/epidemiologiaRESUMO
The relationship between malaria and malnutrition is complicated, and existence of one may predispose or exacerbate the other. We evaluated the relationship between malaria parasitemia and nutritional status in children living in communities participating in a cluster-randomized trial of biannual azithromycin compared with placebo for prevention of childhood mortality. Data were collected during the low malaria transmission and low food insecurity season. Parasitemia was not associated with weight-for-height Z-score (24 months: P = 0.11 azithromycin communities, P = 0.75 placebo communities), weight-for-age Z-score (24 months: P = 0.83 azithromycin, P = 0.78 placebo), height-for-age Z-score (24 months: P = 0.30 azithromycin, P = 0.87 placebo), or mid-upper arm circumference (24 months: P = 0.12 azithromycin, P = 0.56 placebo). There was no statistically significant evidence of a difference in the relationship in communities receiving azithromycin or placebo. During the low transmission season, there was no evidence that malaria parasitemia and impaired nutritional status co-occur in children.
Assuntos
Antibacterianos/administração & dosagem , Azitromicina/administração & dosagem , Malária/epidemiologia , Administração Massiva de Medicamentos , Estado Nutricional , Parasitemia/epidemiologia , Pré-Escolar , Feminino , Humanos , Lactente , Malária/tratamento farmacológico , Malária/parasitologia , Malária/transmissão , Masculino , Níger/epidemiologia , Parasitemia/tratamento farmacológico , Parasitemia/parasitologia , Parasitemia/transmissão , Estações do AnoRESUMO
Experiments on infections caused by trypanosomes are widely performed in Swiss white mice through various inoculation routes. To better understand the effect of route of trypanosome inoculation on disease outcomes in this model, we characterised the virulence of two isolates, Trypanosoma brucei KETRI 2710 and T. congolense KETRI 2765 in Swiss white mice. For each of the isolates, five routes of parasite inoculation, namely intraperitoneal (IP), subcutaneous (SC), intramuscular (IM) intradermal (ID) and intravenous (IV) were compared using groups (n = 6) of mice, with each mouse receiving 1x104 trypanosomes. We subsequently assessed impact of the routes on disease indices that included pre-patent period (PP), parasitaemia levels, Packed Cell Volume (PCV), bodyweight changes and survival time. Pre-patent period for IP inoculated mice was a mean ± SE of 3.8 ± 0.2 and 6.5 ± 0.0 for the T brucei and T. congolense isolates respectively; the PP for mice groups inoculated using other routes were not significantly different(p> 0.05) irrespective of route of inoculation and species of trypanosomes. With ID and IP routes, parasitaemia was significantly higher in T. brucei and significantly lower in T. congolense infected mice and the progression to peak parasitaemia routes showed no significant different between the routes of either species of trypanosome. The IM and ID routes in T. congolense inoculations, and IP and IV in T. b. brucei induced the fastest and slowest parasitaemia progressions respectively. There were significant differences in rates of reduction of PCV with time post infection in mice infected by the two species and which was more pronounced in sc and ip injected mice. No significant differences in mice body weight changes and survivorship was observed between the routes of inoculation. Inoculation route therefore appears to be a critical determinant of pathogenicity of Trypanosoma congolense and Trypanosoma brucei brucei in murine mouse model of African trypanosomiasis.
Assuntos
Parasitemia/parasitologia , Trypanosoma brucei brucei/patogenicidade , Trypanosoma congolense/patogenicidade , Tripanossomíase Africana/parasitologia , Animais , Modelos Animais de Doenças , Humanos , Camundongos , Parasitemia/transmissão , Tripanossomíase Africana/transmissão , Vacinação , VirulênciaRESUMO
OBJECTIVE: The aim of this study was to assess the occurrence of malaria outbreak and investigate contracting factors of malaria in Simada District, Northwest Ethiopia. A single observation original research. RESULTS: Among the total 54 cases, 44 (81.5%) of them were confirmed malaria cases. The average attack rate was 20 per 100 and slide positivity rate was 81.5%. People in the age group of 5-14 years were most affected with an attack rate of 37%. Presence of water bodies for mosquito breeding inside less than 1 km radius (AOR = 3.32, 95% CI 1.18-9.34), no knowledge on transmission, prevention and control mechanisms of malaria (AOR = 4.36, 95% CI 1.64, 12.23), not using Insecticide Treated Bed Net (AOR = 5.85, 95% CI 1.94, 17.54) and absence of environmental control (AOR = 10.01, 95% CI 2.94, 33.33) were factors associated with malaria outbreak.
Assuntos
Surtos de Doenças , Conhecimentos, Atitudes e Prática em Saúde , Malária Falciparum/epidemiologia , Malária Vivax/epidemiologia , Parasitemia/epidemiologia , Adolescente , Estudos de Casos e Controles , Criança , Pré-Escolar , Eritrócitos/parasitologia , Etiópia/epidemiologia , Feminino , Humanos , Incidência , Mosquiteiros Tratados com Inseticida/estatística & dados numéricos , Malária Falciparum/parasitologia , Malária Falciparum/transmissão , Malária Vivax/parasitologia , Malária Vivax/transmissão , Masculino , Parasitemia/parasitologia , Parasitemia/transmissão , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium falciparum/patogenicidade , Plasmodium vivax/crescimento & desenvolvimento , Plasmodium vivax/patogenicidade , Fatores de RiscoRESUMO
Didelphis (Marsupialia, Didelphimorphia) are synanthropic mammals, whose omnivorous diet predisposes them to infections caused by endoparasites. Their higher frequency in urban areas makes them potential carriers of zoonotic protozoans and helminths, enhancing potential transmission to humans. Our purpose was to study two common species, Didelphis albiventris (54 individuals) and D. aurita (2 individuals), which were screened for blood, skin and intestinal parasites in animals captured in urban areas and in riparian forest regions associated with the Capivari River Basin, in Monte Mor's municipality, São Paulo state (SP), Brazil. Blood and tissue samples were collected for DNA extraction and PCR. Fecal samples were collected and submitted to two sedimentation and two flotation methods. 77.6% of fecal samples were positive for nematode eggs, 34.5% for trematode eggs and 32.7% for protozoans. Two D. aurita specimens were naturally infected by Trypanosoma cruzi. Molecular analysis in a D. albiventris captured on a forested rural area was positive for Leishmania sp. DNA. Several parasites were found infecting Didelphis sp., demonstrating that this group of animals can harbor important zoonotic parasites, potentially playing a role as sylvatic reservoirs for human and domestic animal pathogens.
Assuntos
Didelphis/parasitologia , Enteropatias Parasitárias/veterinária , Parasitemia/veterinária , Dermatopatias Parasitárias/veterinária , Animais , Brasil/epidemiologia , Portador Sadio/epidemiologia , Portador Sadio/transmissão , Portador Sadio/veterinária , Cidades , Fezes/parasitologia , Feminino , Florestas , Humanos , Enteropatias Parasitárias/epidemiologia , Enteropatias Parasitárias/transmissão , Masculino , Parasitemia/epidemiologia , Parasitemia/transmissão , Rios , Dermatopatias Parasitárias/epidemiologia , Dermatopatias Parasitárias/transmissão , Zoonoses/parasitologia , Zoonoses/transmissãoRESUMO
Effective malaria control strategies require an accurate understanding of the epidemiology of locally transmitted Plasmodium species. Compared to Plasmodium falciparum infection, Plasmodium vivax has a lower asexual parasitaemia, forms dormant liver-stages (hypnozoites), and is more transmissible. Hence, treatment and diagnostic policies aimed exclusively at P. falciparum are far less efficient against endemic P. vivax. Within sub-Saharan Africa, malaria control programmes justly focus on reducing the morbidity and mortality associated with P. falciparum. However, the recent emphasis on malaria elimination and increased accessibility of more sensitive diagnostic tools have revealed greater intricacies in malaria epidemiology across the continent. Since 2010, the number of studies identifying P. vivax endemic to Africa has expanded considerably, with 88 new scientific reports published since a review of evidence in 2015, approximately doubling the available data. There is evidence of P. vivax in all regions of Africa, apparent from infected vectors, clinical cases, serological indicators, parasite prevalence, exported infections, and P. vivax-infected Duffy-negative individuals. Where the prevalence of microscopic parasitaemia is low, a greater proportion of P. vivax infections were observed relative to P. falciparum. This evidence highlights an underlying widespread presence of P. vivax across all malaria-endemic regions of Africa, further complicating the current practical understanding of malaria epidemiology in this region. Thus, ultimate elimination of malaria in Africa will require national malaria control programmes to adopt policy and practice aimed at all human species of malaria.
Assuntos
Doenças Endêmicas , Malária Vivax/epidemiologia , Malária Vivax/parasitologia , Plasmodium vivax/isolamento & purificação , África/epidemiologia , Sistema do Grupo Sanguíneo Duffy/sangue , Humanos , Malária Falciparum/sangue , Malária Falciparum/epidemiologia , Malária Falciparum/prevenção & controle , Malária Falciparum/transmissão , Malária Vivax/prevenção & controle , Malária Vivax/transmissão , Razão de Chances , Parasitemia/sangue , Parasitemia/epidemiologia , Parasitemia/prevenção & controle , Parasitemia/transmissão , Plasmodium falciparum/isolamento & purificação , PrevalênciaRESUMO
BACKGROUND: Babesiosis is a disease caused by parasites that infect red blood cells; in infants it can be acquired from tick bites, blood transfusions, or congenitally via vertical transmission. It can present with thrombocytopenia, fevers, and parasitemia. CASE REPORT: A case of vertically transmitted babesiosis in an infant is described. Thrombocytopenia and parasitemia > 4% developed in this well-appearing infant. The diagnosis was made by history and blood smear in both infant and mother, and the patient recovered fully with oral antibiotics. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Congenital babesiosis has been reported infrequently in the literature and is reviewed here. It is important to consider congenital tick-borne illness in endemic areas as a cause for febrile thrombocytopenia in neonates.
Assuntos
Babesiose/complicações , Babesiose/diagnóstico , Babesia microti/patogenicidade , Babesiose/transmissão , Febre/etiologia , Humanos , Lactente , Transmissão Vertical de Doenças Infecciosas , Masculino , Parasitemia/complicações , Parasitemia/transmissão , Trombocitopenia/etiologiaRESUMO
Malaria is one of the transfusion transmissible infections in malaria endemic countries such as Ghana. Healthy blood donors may harbour Plasmodium parasites without showing signs of malaria. Blood from such donors constitutes a risk to transfusion recipients and the recipients of this blood may go on to develop transfusion transmitted malaria (TTM). In many malaria endemic countries, blood donors are not screened for Plasmodium parasites. We investigated the prevalence of Plasmodium in blood donors in a hospital in Ghana as well as evaluate health workers knowledge, attitude and practices towards TTM. The study was carried out at the Kwadaso Seventh Day Adventist Hospital in Kumasi, Ghana from September 2016 to May 2017. Blood samples from 100 blood donors and 100 non-donors were examined for Plasmodium using microscopy and a rapid diagnostic test (RDT). In addition the blood groups of participants were determined. To obtain information concerning knowledge, attitude and practices of transfusion transmitted malaria, questionnaires were administered to 100 health workers including doctors, nurses and laboratory technicians. The prevalence rate of Plasmodium parasitaemia in blood donors by RDT and microscopy was 8% and 3% respectively, compared to non-donors who had a prevalence of 5% and 2% by RDT and microscopy respectively. Out of 100 health workers surveyed, 26% (26/100) had never heard of transfusion transmitted malaria. In an emergency situation, 41% health workers were willing to transfuse malaria positive blood but only 2%, 4% and 8% were willing to transfuse blood that was positive for HIV, Hepatitis B and Syphilis respectively. Regular training workshops may help improve the knowledge of health workers as a quarter of workers had not heard about transfusion transmitted malaria and 6.8% did not know that malaria was transmissible by transfusion.
Assuntos
Doadores de Sangue/estatística & dados numéricos , Transfusão de Sangue/estatística & dados numéricos , Conhecimentos, Atitudes e Prática em Saúde , Pessoal de Saúde/estatística & dados numéricos , Malária/transmissão , Parasitemia/epidemiologia , Plasmodium/fisiologia , Adolescente , Adulto , Doadores de Sangue/psicologia , Feminino , Gana/epidemiologia , Pessoal de Saúde/psicologia , Humanos , Masculino , Pessoa de Meia-Idade , Parasitemia/transmissão , Prevalência , Inquéritos e Questionários , Reação Transfusional/epidemiologia , Adulto JovemRESUMO
Host susceptibility to parasites is likely to be influenced by intrinsic factors, such as host oxidative status determined by the balance between pro-oxidant production and antioxidant defences. As a result, host oxidative status acts as an environmental factor for parasites and may constrain parasite development. We evaluated the role of host oxidative status on infection dynamics of an avian malarial parasite by providing canaries (Serinus canaria) with an antioxidant supplementation composed of vitamin E (a lipophilic antioxidant) and olive oil, a source of monounsaturated fatty acids. Another group received a standard, non-supplemented food. Half of the birds in each group where then infected with the haemosporidian parasite, Plasmodium relictum. We monitored the parasitaemia, haematocrit level, and red cell membrane resistance, as well as the transmission success of the parasite to its mosquito vector, Culex pipiens. During the acute phase, the negative effect of the infection was more severe in the supplemented group, as shown by a lower haematocrit level. Parasitaemia was lower in the supplemented group during the chronic phase only. Mosquitoes fed on supplemented hosts were more often infected than mosquitoes fed on the control group. These results suggest that dietary antioxidant supplementation conferred protection against Plasmodium in the long term, at the expense of a short-term negative effect. Malaria parasites may take advantage of antioxidants, as shown by the increased transmission rate in the supplemented group. Overall, our results suggest an important role of oxidative status in infection outcome and parasite transmission.
Assuntos
Antioxidantes/metabolismo , Culex/fisiologia , Malária Aviária/parasitologia , Mosquitos Vetores/parasitologia , Parasitemia/veterinária , Plasmodium/fisiologia , Animais , Canários/metabolismo , Canários/parasitologia , Culex/parasitologia , Comportamento Alimentar , Feminino , Malária Aviária/metabolismo , Malária Aviária/transmissão , Masculino , Mosquitos Vetores/fisiologia , Azeite de Oliva/metabolismo , Estresse Oxidativo , Parasitemia/parasitologia , Parasitemia/transmissão , Vitamina E/metabolismoRESUMO
Currently, there are very few studies of avian malaria that investigate relationships among the host-vector-parasite triad concomitantly. In the current study, we experimentally measured the vector competence of several Culex mosquitoes for a newly described avian malaria parasite, Plasmodium homopolare. Song sparrow (Melospiza melodia) blood infected with a low P. homopolare parasitemia was inoculated into a naïve domestic canary (Serinus canaria forma domestica). Within 5 to 10 days post infection (dpi), the canary unexpectedly developed a simultaneous high parasitemic infection of Plasmodium cathemerium (Pcat6) and a low parasitemic infection of P. homopolare, both of which were detected in blood smears. During this infection period, PCR detected Pcat6, but not P. homopolare in the canary. Between 10 and 60 dpi, Pcat6 blood stages were no longer visible and PCR no longer amplified Pcat6 parasite DNA from canary blood. However, P. homopolare blood stages remained visible, albeit still at very low parasitemias, and PCR was able to amplify P. homopolare DNA. This pattern of mixed Pcat6 and P. homopolare infection was repeated in three secondary infected canaries that were injected with blood from the first infected canary. Mosquitoes that blood-fed on the secondary infected canaries developed infections with Pcat6 as well as another P. cathemerium lineage (Pcat8); none developed PCR detectable P. homopolare infections. These observations suggest that the original P. homopolare-infected songbird also had two un-detectable P. cathemerium lineages/strains. The vector and host infectivity trials in this study demonstrated that current molecular assays may significantly underreport the extent of mixed avian malaria infections in vectors and hosts.
Assuntos
Coinfecção/veterinária , Culex/fisiologia , Malária Aviária/parasitologia , Mosquitos Vetores/fisiologia , Parasitemia/veterinária , Plasmodium/fisiologia , Animais , Canários/parasitologia , Coinfecção/parasitologia , Coinfecção/transmissão , Culex/parasitologia , Malária Aviária/transmissão , Mosquitos Vetores/parasitologia , Parasitemia/parasitologia , Parasitemia/transmissão , Passeriformes/parasitologia , Plasmodium/genéticaRESUMO
BACKGROUND: In the context of reduced transmission of malaria, it is essential to re-evaluate and determine the level of transmission as it guides re-orientation of control measures which is appropriate to local disease epidemiology. However, little is known about level of malaria transmission in Ethiopia. The present study aimed to investigate the level of malaria transmission through combined application of classical methods and enzyme-linked immunosorbent assay (EIA) in low transmission settings of Ethiopia. METHODS: This study was conducted in June 2016 on 763 apparently healthy children 2-9 years of age. Children were recruited from ten sites representing different malaria transmission settings in Ethiopia. Splenomegaly rate, infection rate and EIA antibody test were used to determine endemicity. The data were analysed using SPSS 21.0 and Stata 12.0. RESULTS: The overall prevalence of malaria parasitaemia was 2.49% (95% CI 1.38-3.59) and 2.36% (95% CI 1.28-3.44) as detected using rapid diagnostic test and microscopy, respectively. Plasmodium falciparum accounted for 62.63% of the infections. The prevalence of parasitaemia significantly varied by altitude and localities; the highest (5.8%) in areas below 1500 m above sea level. Overall, splenomegaly rate was 1.70% (95% CI 0.78-0.2.66%), making the overall malaria transmission hypoendemic. Infection rate was higher among males (2.7%), but rate of splenomegaly was higher in females. Incongruent with spleen rate and parasitaemia, EIA showed a higher level of cumulative exposure to malaria with spatially localized and highly heterogeneous transmission. Overall, 126 (18.75%, 95% CI 15.79-21.71) of the children were positive for total malaria antibodies with significant variations with altitude, age and sex; the higher in areas of < 1500 m asl (25.8%), children ≥ 5 years (22.1%) and among males (20.9%). CONCLUSIONS: Splenomegaly and parasitaemia are not good measures to show variations in the levels of malaria transmission in reduced and/or low endemic settings. The malaria antibody (i.e. serological) test seems to be a good measure of malaria endemicity showing greater degree of heterogeneity and localized risk of transmission. Thus, malaria elimination efforts need to be supported with serological indicators to identify patterns of foci of transmission to set priorities for interventions.
Assuntos
Doenças Endêmicas , Malária/epidemiologia , Malária/transmissão , Parasitemia/epidemiologia , Parasitemia/transmissão , Esplenomegalia/epidemiologia , Adolescente , Criança , Pré-Escolar , Testes Diagnósticos de Rotina , Ensaio de Imunoadsorção Enzimática , Etiópia/epidemiologia , Humanos , Malária/parasitologia , Microscopia , Parasitemia/parasitologia , Plasmodium/isolamento & purificação , Prevalência , Esplenomegalia/parasitologiaRESUMO
Malaria transmission-blocking vaccines (TBV) have been evaluated in field trials in Mali since 2013. However, the assays currently used to measure serum antibody TB activity (TBA) after vaccination are highly variable, in part due to the lack of optimization and standardization for field assays in which mosquitoes feed on gametocytemic blood. Herein, we report a study conducted in Bancoumana village, Mali, where we identify and optimize the parameters that contribute to successful mosquito feeding outcomes in both direct skin feeds (DSFs) and direct membrane feeding assays (DMFA). These parameters include: 1) mosquito age, 2) duration of mosquito starvation prior to feeding, 3) membrane selection for DMFA, 4) anatomical location of DSF feeding (arm, calf, and ankle), and 5) time of day for DSF (dawn or dusk). We found that younger mosquitoes were significantly associated with higher feeding, survival, and infection rates. Longer starvation times were positively, but not significantly, associated with higher infection rates, but were negatively associated with feeding and survival. Membrane type and body location did not affect infection outcome significantly. Although dusk was found to be associated with higher infection rates, this may be confounded by the time from positive blood smear. Based on these findings, we make specific recommendations for optimal feeding parameters in the different assay types to maximize the chance of detecting parasite transmission in a standardized manner.
Assuntos
Anopheles/fisiologia , Insetos Vetores/fisiologia , Vacinas Antimaláricas/imunologia , Malária Falciparum/prevenção & controle , Membranas Artificiais , Plasmodium falciparum/fisiologia , Adolescente , Adulto , Envelhecimento , Animais , Anopheles/parasitologia , Comportamento Alimentar , Humanos , Insetos Vetores/parasitologia , Malária Falciparum/parasitologia , Malária Falciparum/transmissão , Mali/epidemiologia , Parasitemia/transmissão , PeleRESUMO
AbstractMalaria incidence is highly heterogeneous even in areas of high transmission, although no conclusive evidence exists that innate or naturally acquired resistance can prevent infection over an extended period of time. This longitudinal study examined immunoparasitological evidence for a malaria-resistant phenotype in which children do not develop malaria despite an extended period of exposure to parasites. Within a birth cohort followed from 2002 to 2006 in Muheza, Tanzania, an area of intense transmission, children (N = 687) provided blood smears biweekly during infancy and monthly thereafter. Maternal and childhood characteristics were obtained, cord-blood cytokines were measured, and antibody responses were assayed as measures of stage-specific exposure. Sixty-three (9.2%) children had no blood smear-positive slides over 2 years of follow-up (range: 1-3.5 years) and were identified as malaria resistant. Malaria-resistant children were similar to other children with respect to completeness of follow-up and all maternal and childhood characteristics except residence area. Antibody seroprevalence was similar for two sporozoite antigens, but malaria-resistant children had a lower antibody seroprevalence to merozoite antigens merozoite surface protein 1 (5.4% versus 30.2%; P < 0.0001) and apical membrane antigen 1 (7.2% versus 33.3%; P < 0.0001). Malaria-resistant children had higher cytokine levels in cord blood, particularly interleukin-1ß. In summary, a subset of children living in an area of intense transmission was exposed to malaria parasites, but never developed patent parasitemia; this phenotype was associated with a distinct cytokine profile at birth and antibody profile during infancy. Further research with malaria-resistant children may identify mechanisms for naturally acquired immunity.
Assuntos
Imunidade Adaptativa , Anticorpos Antiprotozoários/biossíntese , Antígenos de Protozoários/sangue , Interleucina-1beta/biossíntese , Malária Falciparum/prevenção & controle , Proteínas de Membrana/sangue , Proteína 1 de Superfície de Merozoito/sangue , Parasitemia/prevenção & controle , Proteínas de Protozoários/sangue , Adolescente , Adulto , Antígenos de Protozoários/imunologia , Pré-Escolar , Resistência à Doença , Feminino , Sangue Fetal/química , Sangue Fetal/imunologia , Humanos , Lactente , Estudos Longitudinais , Malária Falciparum/imunologia , Malária Falciparum/parasitologia , Malária Falciparum/transmissão , Masculino , Proteínas de Membrana/imunologia , Proteína 1 de Superfície de Merozoito/imunologia , Pessoa de Meia-Idade , Parasitemia/imunologia , Parasitemia/transmissão , Fenótipo , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium falciparum/patogenicidade , Proteínas de Protozoários/imunologia , TanzâniaRESUMO
BACKGROUND: Malaria control interventions have led to a decline in transmission intensity in many endemic areas, and resulted in elimination in some areas. This decline, however, will lead to delayed acquisition of protective immunity and thus impact disease manifestation and outcomes. Therefore, the variation in clinical and haematological parameters in children with malaria was assessed across three areas in Ghana with varying transmission intensities. METHODS: A total of 568 children between the ages of 2 and 14 years with confirmed malaria were recruited in hospitals in three areas with varying transmission intensities (Kintampo > Navrongo > Accra) and a comprehensive analysis of parasitological, clinical, haematological and socio-economic parameters was performed. RESULTS: Areas of lower malaria transmission tended to have lower disease severity in children with malaria, characterized by lower parasitaemias and higher haemoglobin levels. In addition, total white cell counts and percent lymphocytes decreased with decreasing transmission intensity. The heterozygous sickle haemoglobin genotype was protective against disease severity in Kintampo (P = 0.016), although this was not significant in Accra and Navrongo. Parasitaemia levels were not a significant predictor of haemoglobin level after controlling for age and gender. However, higher haemoglobin levels in children were associated with certain socioeconomic factors, such as having fathers who had any type of employment (P < 0.05) and mothers who were teachers (P < 0.05). CONCLUSIONS: The findings demonstrate significant differences in the haematological presentation and severity of malaria among areas with different transmission intensity in Ghana, indicating that these factors need to be considered in planning the management of the disease as the endemicity is expected to decline after control interventions.
Assuntos
Malária/fisiopatologia , Malária/transmissão , Adolescente , Criança , Pré-Escolar , Feminino , Gana , Humanos , Malária/sangue , Malária/parasitologia , Masculino , Parasitemia/sangue , Parasitemia/parasitologia , Parasitemia/fisiopatologia , Parasitemia/transmissãoRESUMO
BACKGROUND: Trypanosoma cruzi is endemic to the Americas where it demonstrates multiple lineages over a vast geographic range (i.e., United States to Argentina). These lineages possess divergent geographic and biologic characteristics, including variations in disease manifestations. Herein, we report the frequency of parasitemia among seropositive US blood donors and the potential association between parasite lineage and transfusion transmission. STUDY DESIGN AND METHODS: Blood donors identified as T. cruzi seropositive during screening were enrolled in follow-up studies, including hemoculture testing and a risk factor questionnaire. Positive hemocultures were expanded to obtain sufficient parasites for molecular lineage determination and analysis. Country of birth, obtained from the questionnaire, was used to predict parasite lineage in the absence of demonstrable parasitemia for infected donors. RESULTS: Eighteen (6.8%) of 263 seropositive donors were hemoculture positive. Among the 17 hemocultures expanded for lineage determination, TcV was identified more frequently (n = 12), compared to TcI (n = 2), TcII (n = 1), and TcVI (n = 2). When presumptive parasite lineages were compared to hemoculture results, only two of 157 (1.3%) TcI versus 13 of 38 (34.2%) TcII/TcV/TcVI non-US donors were parasitemic; three of 44 (6.8%) US donors were TcV or TcVI. CONCLUSIONS: Based on lineage determination for donors with parasitemia; hemoculture positivity associated with presumptive parasite lineage; and implicated donors from US, Canadian, and Spanish transfusion cases, donors from Southern South America are significantly more likely to have parasitemia and transmit infection to blood recipients (TcII, TcV, or TcVI vs. TcI). Thus, parasite lineage may be associated with risk of transfusion-transmitted T. cruzi.
Assuntos
Doadores de Sangue/estatística & dados numéricos , Parasitemia/epidemiologia , Reação Transfusional , Trypanosoma cruzi/patogenicidade , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Parasitemia/parasitologia , Parasitemia/transmissão , Reação em Cadeia da Polimerase , Fatores de Risco , Inquéritos e Questionários , Adulto JovemRESUMO
Many reproductive problems has been described in male and female animals infected by Trypanosoma evansi. Thus, the aim of this study was to evaluate the occurrence of vertical (Experiment I) and venereal (Experiment II) transmission of T. evansi in rats experimentally infected. In the experiment I, eight female Wistar rats were used: three animals as negative controls, and five rats were infected by T. evansi on day ten of gestation. Out of these eight females, half puppies were used for molecular analysis (polymerase chain reaction - PCR) for T. evansi. Two infected females showed delivery problems, such as stillbirth, and fetal death that also led to female death. Three female rats infected had normal delivery of stunted offspring at term that died 2 days after birth. Rats from the control group had normal delivery of healthy offspring. T. evansi PCR was positive for 80% (12/15) of pups in the infected group. For the experiment II, five male rats were infected by T. evansi, and monitored by blood smears to check the parasitemia level. When the male rats showed parasitemia between 2 and 5 parasites per field, they were individually housed with one female adult rat. After approximately 21 days, the females delivered their offspring. Blood sample was collected from the females for blood smears and T. evansi PCR tests, which revealed negative results. Therefore, we were able to prove the occurrence of transplacental transmission of T. evansi and its negative effect on female rats and their offspring.
Assuntos
Transmissão Vertical de Doenças Infecciosas , Infecções Sexualmente Transmissíveis/transmissão , Tripanossomíase/transmissão , Animais , Antígenos CD/genética , Apirase/genética , DNA de Protozoário/isolamento & purificação , Cães , Feminino , Hidroximetilglutaril-CoA Redutases/genética , Masculino , Parasitemia/transmissão , Reação em Cadeia da Polimerase , Gravidez , Ratos , Ratos Wistar , Trypanosoma/genética , Trypanosoma/isolamento & purificação , Trypanosoma/fisiologiaRESUMO
Nurses are likely to be exposed to microorganisms during their daily practice due to their close and frequent direct contact with patients. This could be one of the main causes of transmitting infection to the patients. Therefore, nurses should demonstrate the ability to effectively utilize principles of infection control, nurses should have professional and ethical responsibilities to make sure that their knowledge and skills regarding infection control are up-to-date and they practice safely and competently at all times. AIM: At assessing the effect of a training program for Military nursing staff knowledge, performance and attitude related to blood parasites acquired by needle stick injury. SETTING: The study was carried out at two military hospitals. Design An interventional study (pre-post study) was used. SUBJECT: The studied subjects were 90 nursing staff who accepted to participate in the study (10) of them pilot study were excluded from the study sample, (30) from The Military Fever Hospital and (50) from The Military General Hospital. Tools: The study tools used were composed of five tools as follows: (1) Educational needs assessment tool. (2) Knowledge questionnaire sheet (pre / post-test) (3) Observation check list (4) Attitude tool and (5) Participants 'evaluation Questionnaire sheet. RESULTS: Educational the intervention showed statistically significant improvements in nursing staff knowledge, performance and attitude. RECOMMENDATION: Continues training programs about blood parasites acquired by needle stick injury must be developed and provided on regular basis, this will enable nursing staff to improve their knowledge, performance and attitude about blood parasites acquired by needle stick injury.
Assuntos
Infecção Hospitalar/etiologia , Hospitais Militares , Ferimentos Penetrantes Produzidos por Agulha/complicações , Recursos Humanos de Enfermagem Hospitalar/educação , Parasitemia/transmissão , Infecções por Protozoários/transmissão , Babesiose/transmissão , Egito , Feminino , Humanos , Controle de Infecções/normas , Leishmaniose Visceral/transmissão , Malária/transmissão , Masculino , Segurança , Toxoplasmose/transmissãoRESUMO
Standard hematological indices are commonly used in malaria epidemiological studies to measure anemia prevalence and calculate blood parasite densities. In Africa, few studies have investigated how these indices change during a malaria transmission season and with increasing age. To address these knowledge gaps, we collected blood from 169 healthy Malian children aged 3-12 years before (May 2010) and after (January 2011) a transmission season. Red blood cell (RBC) count, hemoglobin (Hb) level, hematocrit (Ht), white blood cell (WBC) count, and WBC subsets were measured in paired blood samples, and the data were stratified by month (May, January) and age group (3-5, 6-8, and 9-12 years). From May to January, RBC count (4.53-4.70 × 10(6)/µL; P < 0.0001), Hb level (11.5-11.9 g/dL; P < 0.0001), and Ht (37.1-39.2%; P < 0.0001) increased, and WBC count (6.46-5.96 × 10(3)/µL; P = 0.0006) decreased. From May to January, the prevalence of WBC subsets also changed: 35-43% neutrophils, 6.5-7.6% monocytes, and 53-45% lymphocytes (P < 0.001). These seasonal changes were not associated with the number of malaria episodes experienced in the interim or the presence of RBC polymorphisms. In May, Hb (11.2, 11.4, and 11.8 g/dL; P = 0.0013) and Ht (36.5%, 36.7%, and 38.1%; P = 0.0154) increased and WBC count (8.04, 6.43, and 5.76 × 10(3)/µL; P < 0.0001) decreased with age group; similar differences were observed in January. These data suggest that season- and age-based reference values for hematological indices are needed to better estimate anemia prevalence and parasite density in malaria epidemiological studies.