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Toxoplasmosis is a global health threat in which occurrence in pregnant women poses grave consequences to fetal wellbeing. Studies on prenatal Toxoplasma gondii infection are generally limited in sub-Saharan African countries, including Nigeria. The risk of transmission of toxoplasmosis is very high in Nigeria due to the favourable climatic conditions and prevailing behavioural and socio-economic factors that could aid transmission. Currently, there are no systematic and organized procedures for diagnosis and treatment of maternal toxoplasmosis in Nigeria. These conditions forecast possible unabated transmission in many areas and exponential impact on associated adverse events of the disease during pregnancy. This paper highlights the importance of early diagnosis and treatment during pregnancy which may forestall subsequent development of infection in children delivered by infected mothers. Inclusion of toxoplasmosis control policy in the routine antenatal care of pregnant women is therefore strongly recommended.
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Complicações Parasitárias na Gravidez/parasitologia , Toxoplasmose Congênita/epidemiologia , Toxoplasmose Congênita/prevenção & controle , Feminino , Humanos , Recém-Nascido , Nigéria/epidemiologia , Gravidez , Complicações Parasitárias na Gravidez/epidemiologia , Complicações Parasitárias na Gravidez/terapia , Toxoplasmose Congênita/parasitologiaRESUMO
BACKGROUND: Plasmodium falciparum EBA175 and PfRh2 belong to two main families involved in parasite invasion, and both are potential vaccine candidates. Current knowledge is limited regarding which target antigens and subclasses of antibodies are actually important for protection, and how naturally acquired immunity is achieved. METHODS: Repeated blood samples were collected from individuals in Nigeria over a period of almost one year. ELISA was used to analyse subclasses of IgG responses. RESULTS: For both EBA175 (region III-V) and (a fragment of) PfRh2, the dominant antibody responses consisted of IgG1 and IgG3 followed by IgG2, while for PfRh2 there was also a relatively prominent response for IgG4. High levels of IgG1, IgG2 and IgG3 for EBA175 and total IgG for PfRh2 correlated significantly with a lower parasitaemia during the study period. Children with HbAS had higher levels of some subclasses compared to children with HbAA, while in adults the pattern was the opposite. The half-lives of IgG2 and IgG4 against EBA175 were clearly shorter than those for IgG1 and IgG3. CONCLUSION: EBA175 and PfRh2 are potential targets for protective antibodies since both correlated with lower parasitaemia. The shorter half-lives for IgG2 and IgG4 might explain why these subclasses are often considered less important in protection against malaria. Triggering the right subclass responses could be of critical importance in a successful vaccine. Further studies are needed to evaluate the role of haemoglobin polymorphisms and their malaria protective effects in this process.
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Anticorpos Antiprotozoários/classificação , Imunoglobulina G/classificação , Malária Falciparum/imunologia , Plasmodium falciparum/imunologia , Proteínas de Protozoários/imunologia , Adolescente , Adulto , Idoso , Anticorpos Antiprotozoários/sangue , Anticorpos Antiprotozoários/imunologia , Antígenos de Protozoários/imunologia , Criança , Pré-Escolar , Feminino , Hemoglobina A , Humanos , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Estudos Longitudinais , Malária Falciparum/epidemiologia , Masculino , Pessoa de Meia-Idade , Nigéria/epidemiologia , Parasitemia , Adulto JovemRESUMO
Aims: One of the ways to manage the current coronavirus disease 2019 (COVID-19) pandemic is to monitor the public knowledge, risk perceptions, adherence to preventive measures, and level of preparedness behaviors. This is important in resource-limited countries. This study determined the knowledge and perception regarding COVID-19; adherence to COVID-19 preventive measures; as well as predictors of self-perceived risk of contracting COVID-19 among Nigerian adults. Methods: A cross-sectional study was conducted among Nigerian adults ≥18 years using an online survey. A convenience sampling method was utilized to recruit a total of 1022 study participants. The participants were recruited using the authors' social media networks. Data were analyzed using descriptive and inferential statistics at a 5% level of statistical significance. Results: Generally, a high proportion of respondents had correct knowledge about COVID-19. However, only approximately half (49.8% and 49.9%) had correct knowledge that obesity was a risk factor for COVID-19 and that antibiotics cannot be used to treat COVID-19. Most (84.1%) did not have a self-perceived risk of contracting COVID-19. Most (81.0%) have been avoiding crowded places and 61.3% washed their hands frequently. Predictors of self-perceived risk of COVID-19 were age 40-59 years (OR 2.05, CI 1.217-3.435), ≥ 60 years (OR 4.68, CI 1.888-11.583), and visiting crowded places (OR 2.27, CI 1.499-3.448). Conclusion: Our study recommends more rigorous public health education aimed at improving COVID-19 outbreak response in Nigeria. In addition, physical and social distancing should be emphasized across all age groups with additional focus on the older population.
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BACKGROUND: The absence of antibodies specific for the 19 kDa C-terminal domain of merozoite surface protein 1 (MSP119) has been associated with high-density malaria parasitaemia in African populations. The hypothesis that a high prevalence and/or level of anti-MSP119 antibodies that may inhibit erythrocyte invasion would be present in apparently healthy individuals who harbour a sub-microscopic malaria infection was tested in this study. METHODS: Plasma samples were collected from residents in a region in Nigeria hyperendemic for malaria, who had no detectable parasitaemia by microscopy. Using a competition-based enzyme-linked-immunosorbent assay with two invasion-inhibitory monoclonal antibodies (mAbs) 12.10 and 12.8, the levels and prevalence of specific antibodies were measured. The minimum multiplicity of infection was determined using PCR. The prevalence of anaemia was also measured. RESULTS: Plasma samples from 85% of individuals contained antibodies that bound to MSP119. The inhibition of mAb 12.10 binding was strongly correlated with the prevalence (Spearman correlation test, p < 0.0001) and mean titre of anti-MSP119 antibodies (Spearman correlation test, p < 0.001) in the samples. Comparing samples from individuals with multiple infection (group M) and single infection (Group S), group M contained a higher (p = 0.04) prevalence of anti-MSP119 antibodies that competed with mAb 12.10. Using a logistic regression model, it was found that the presence of antibodies competitive with mAb 12.10 was affected negatively by anaemia (p = 0.0016) and positively by the carriage of multiple parasite genotypes (p = 0.04). CONCLUSIONS: In the search for correlates of protection against malaria, which will be essential to evaluate clinical trials of malaria vaccines based on MSP1, this study examines some potential assays and the factors that need to taken into account during their evaluation, using samples from individuals naturally exposed to malaria infection.
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Anticorpos Antiprotozoários/imunologia , Portador Sadio/imunologia , Malária Falciparum/imunologia , Proteína 1 de Superfície de Merozoito/genética , Proteína 1 de Superfície de Merozoito/imunologia , Parasitemia/parasitologia , Plasmodium falciparum/imunologia , Adolescente , Adulto , Anticorpos Monoclonais , Sangue/imunologia , Sangue/parasitologia , Portador Sadio/parasitologia , Criança , Pré-Escolar , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Lactente , Recém-Nascido , Malária Falciparum/parasitologia , Masculino , Microscopia , Nigéria , Plasmodium falciparum/isolamento & purificação , Reação em Cadeia da PolimeraseRESUMO
BACKGROUND: Dizygotic (DZ, non-identical) twinning rates vary widely across different regions in the world. With a DZ twinning rate of 45 per 1000 live births, Igbo-Ora Community in South-west Nigeria has the highest dizygotic (DZ) twinning rate in the world. Although several postulations exist on the causes of high DZ twinning rates in Igbo-Ora, no study has yet been conclusive on a definite causative agent. OBJECTIVE: Using qualitative methods, this study explored the perceptions and beliefs of Igbo-Ora residents about the causes of high DZ twinning rates. METHODS: Focus group discussion sessions and key informant interviews were organized among fathers and mothers of twins, those without twins, and health care providers. Key informant interviews were also held with persons considered to be custodians of culture who may have knowledge relevant to twinning such as traditional rulers, and traditional birth attendants; as well as health care providers, mothers and fathers of twins, and adult twins. RESULTS: The results showed three factors featuring as the leading perceived causes of twinning in the community. These included twinning being an act of God, hereditary, and being due to certain foods consumed in the community. Contrary to reports that the consumption of a species of yam (Dioscorea rotundata) may be responsible for the DZ twinning in this Community; yam was not prioritized by the respondents as associated with twinning. In contrast, participants repeatedly mentioned the consumption of "ilasa" a soup prepared with okra leaves (Abelmoschus esculenta) with water that is obtained from the community, and "amala" a local delicacy produced from cassava (Manihot esculenta) as the most likely dietary factors responsible for twinning in the community. CONCLUSION: Since the same foods are consumed in neighboring communities that have lower rates of twinning, we conjecture that nutritional and other environmental factors may produce epigenetic modifications that influence high DZ twinning rates in Igbo-Ora community. We conclude that more directed scientific studies based on these findings are required to further elucidate the etiology of the high rate of DZ twinning in Igbo-Ora.
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Cultura , Gêmeos Dizigóticos , Adulto , Dieta , Epigênese Genética , Comportamento Alimentar , Feminino , Grupos Focais , Humanos , Masculino , Nigéria , Gravidez , Pesquisa Qualitativa , Gêmeos Dizigóticos/genética , Gêmeos Dizigóticos/estatística & dados numéricosRESUMO
BACKGROUND: MSP1 processing-inhibitory antibodies bind to epitopes on the 19 kDa C-terminal region of the Plasmodium falciparum merozoite surface protein 1 (MSP1(19)), inhibiting erythrocyte invasion. Blocking antibodies also bind to this antigen but prevent inhibitory antibodies binding, allowing invasion to proceed. Recombinant MSP1(19) had been modified previously to allow inhibitory but not blocking antibodies to continue to bind. Immunization with these modified proteins, therefore, has the potential to induce more effective protective antibodies. However, it was unclear whether the modification of MSP1(19) would affect critical T-cell responses to epitopes in this antigen. METHODS: The cellular responses to wild-type MSP1(19) and a panel of modified MSP1(19) antigens were measured using an in-vitro assay for two groups of individuals: the first were malaria-naïve and the second had been naturally exposed to Plasmodium falciparum infection. The cellular responses to the modified proteins were examined using cells from malaria-exposed infants and adults. RESULTS: Interestingly, stimulation indices (SI) for responses induced by some of the modified proteins were at least two-fold higher than those elicited by the wild-type MSP1(19). A protein with four amino acid substitutions (Glu27-->Tyr, Leu31-->Arg, Tyr34-->Ser and Glu43-->Leu) had the highest stimulation index (SI up to 360) and induced large responses in 64% of the samples that had significant cellular responses to the modified proteins. CONCLUSION: This study suggests that specific MSP1(19) variants that have been engineered to improve their antigenicity for inhibitory antibodies, retain T-cell epitopes and the ability to induce cellular responses. These proteins are candidates for the development of MSP1-based malaria vaccines.
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Antígenos de Protozoários/imunologia , Epitopos de Linfócito T/imunologia , Malária Falciparum/imunologia , Proteína 1 de Superfície de Merozoito/metabolismo , Plasmodium falciparum/imunologia , Adolescente , Adulto , Anticorpos Bloqueadores/imunologia , Anticorpos Antiprotozoários/sangue , Anticorpos Antiprotozoários/imunologia , Feminino , Glutationa Transferase/metabolismo , Humanos , Vacinas Antimaláricas/imunologia , Masculino , Proteína 1 de Superfície de Merozoito/imunologia , Fito-Hemaglutininas , Plasmodium falciparum/crescimento & desenvolvimento , Proteínas de Protozoários/imunologia , Proteínas de Protozoários/metabolismo , Adulto JovemRESUMO
Enhanced antimalarial activity of plant extracts used for treatment of malaria in endemic areas is attributed to partial immunity gained by prior infection. This suggests synergy between immunity and extract activity in treatment. Testing this hypothesis, rodent malaria was used to determine efficacy of Lophira alata leaf extracts in treating malaria in prior infected mice. One round of P. berghei infection and Pyrimethamine drug-cure was used to establish partial immunity in mice. Previously Exposed Mice (PEM) and Previously Unexposed Mice (PUM) mice challenged with P. berghei were used to determine influence of partial antimalarial immunity on efficacy of L. alata leaf extracts, administered alone or in combination with Artesunate (ART) in malaria treatment. There was a significant reduction in parasitemia in PEM when compared to PUM animals (P<0.001) irrespective of treatment regimen. Administration of L. alata combined with ART significantly reduced parasitemia (P<0.0032) and prolonged (P=0.0109) survival than when L. alata was administered alone in infected mice. These findings suggest that the action of L. alata in treating malaria infections in a murine model is enhanced by prior exposure to the malaria parasite. Thus the requirements of using plants in treating malaria in endemic populations may differ for those used in western systems, where trials are carried out with non-immune cohorts. Combining artemisinin derivatives and medicinal plants in malaria exposed populations may provide an alternative control measure in endemic regions and may justify the continued use of these plants by indigenous populations in treating malaria.
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Artemisininas/farmacologia , Malária/tratamento farmacológico , Ochnaceae/química , Extratos Vegetais/farmacologia , Folhas de Planta/química , Plasmodium berghei/efeitos dos fármacos , Animais , Antimaláricos/química , Antimaláricos/farmacologia , Artesunato , Camundongos , Fitoterapia/métodos , Plantas Medicinais/químicaRESUMO
Understanding the functional characteristics of naturally acquired antibodies against P. falciparum merozoite antigens is crucial for determining the protective functions of antibodies. Affinity (measured as kd) of naturally acquired antibodies against two key targets of acquired immunity, EBA175 and PfRh2, was determined using Surface Plasmon Resonance (SPR) in a longitudinal survey in Nigeria. A majority of the participants, 79% and 67%, maintained stable antibody affinities to EBA175 and PfRh2, respectively, over time. In about 10% of the individuals, there was a reciprocal interaction with a reduction over time in antibody affinity for PfRh2 and an increase for EBA175. In general, PfRh2 elicited antibodies with higher affinity compared to EBA175. Individuals with higher exposure to malaria produced antibodies with higher affinity to both antigens. Younger individuals (5-15 years) produced comparable or higher affinity antibodies than adults (>15 years) against EBA175, but not for PfRh2. Correlation between total IgG (ELISA) and affinity varied between individuals, but PfRh2 elicited antibodies with a higher correlation in a majority of the participants. There was also a correlation between antibody inhibition of erythrocyte invasion by merozoites and PfRh2 affinity. This work gives new insights into the generation and maintenance of antibody affinity over time.
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Anticorpos Antiprotozoários/imunologia , Afinidade de Anticorpos/imunologia , Antígenos de Protozoários/imunologia , Malária Falciparum/imunologia , Merozoítos/imunologia , Plasmodium falciparum/imunologia , Imunidade Adaptativa/imunologia , Adolescente , Adulto , Criança , Pré-Escolar , Humanos , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Estudos Longitudinais , Malária Falciparum/sangue , Malária Falciparum/parasitologia , Nigéria , Plasmodium falciparum/fisiologia , Ressonância de Plasmônio de SuperfícieRESUMO
Erythrocyte-binding antigens (EBAs) and P. falciparum reticulocyte-binding homologue proteins (PfRhs) are two important protein families that can vary in expression and utilization by P. falciparum to evade inhibitory antibodies. We evaluated antibodies at repeated time-points among individuals living in an endemic region in Nigeria over almost one year against these vaccine candidates. Antibody levels against EBA140, EBA175, EBA181, PfRh2, PfRh4, and MSP2, were measured by ELISA. We also used parasites with disrupted EBA140, EBA175 and EBA181 genes to show that all these were targets of invasion inhibitory antibodies. However, antigenic targets of inhibitory antibodies were not stable and changed substantially over time in most individuals, independent of age. Antibodies levels measured by ELISA also varied within and between individuals over time and the antibodies against EBA181, PfRh2 and MSP2 declined more rapidly in younger individuals (≤15 years) compared with older (>15). The breadth of high antibody responses over time was more influenced by age than by the frequency of infection. High antibody levels were associated with a more stable invasion inhibitory response, which could indicate that during the long process of formation of immunity, many changes not only in levels but also in functional responses are needed. This is an important finding in understanding natural immunity against malaria, which is essential for making an efficacious vaccine.
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Anticorpos Antiprotozoários/sangue , Antígenos de Protozoários/imunologia , Evasão da Resposta Imune , Malária Falciparum/imunologia , Plasmodium falciparum/imunologia , Proteínas de Protozoários/imunologia , Adolescente , Adulto , Idoso , Envelhecimento/imunologia , Criança , Pré-Escolar , Doenças Endêmicas , Humanos , Imunoglobulina G/sangue , Estimativa de Kaplan-Meier , Estudos Longitudinais , Malária Falciparum/epidemiologia , Pessoa de Meia-Idade , Nigéria , Proteínas de Protozoários/sangue , Estações do Ano , Adulto JovemRESUMO
Transmission of schistosomiasis is aided by human behaviour. Globally, about 800 million people are at risk of schistosomiasis infection. Data exist on biomedical understanding of the disease transmission; there is a dearth of information from the social science perspective. Hence, this study explored the social and cultural context of schistosomiasis transmission among Yewa People in Nigeria. Qualitative methods were employed with purposive sampling, using the key informant interviews and focus group discussions, among 57 participants aged 17 to 54 years. The data were content-analyzed. River water was the most reported source of water supply among others. Participants drew from the cultural milieu the use of river water for "drinking" and "swimming" as part of the continual transmission of schistosomiasis. Transmission of schistosomiasis may not be abated without behavioural change.
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BACKGROUND: Rapid and accurate diagnosis is necessary for the management of schistosomiasis in endemic areas. OBJECTIVE: To assess the burden of urogenital schistosomiasis and the diagnostic efficiency of morbidity indicators of the disease in an endemic rural community of Nigeria. METHODS: A cross-sectional school-based study was conducted. Urine samples of 487 pupils were screened microscopically for S. haematobium and tested for haematuria and proteinuria using chemical reagent strips. RESULTS: The prevalence and intensity of infection were 57.1% and 45.0 eggs/10 mL urine respectively. Prevalence of infection in male (54.1%) and female (60.3%) individuals showed no significant variation (P>0.05). However, prevalence of infection was age dependent with those in age groups 3-5 and 12-14 years having the least and highest prevalence of infection respectively (P<0.05). Microhaematuria and proteinuria varied significantly with ages of the pupils with least (14.0, 40.0%) and highest (60.0, 80.0%) prevalence recorded in age groups 3-5 and 15-19 years respectively (P<0.05). Proteinuria showed higher sensitivity (80.3%) compared to microhaematuria (73.3%). CONCLUSION: Schistosomiasis is highly endemic in the study area and the use of microhaematuria and proteinuria for mapping the infected population prior treatment could be adopted.
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Hematúria/urina , Proteinúria/urina , Esquistossomose Urinária/diagnóstico , Esquistossomose Urinária/epidemiologia , Adolescente , Criança , Pré-Escolar , Estudos Transversais , Feminino , Hematúria/parasitologia , Humanos , Masculino , Morbidade , Nigéria/epidemiologia , Prevalência , Proteinúria/parasitologia , População Rural , Esquistossomose Urinária/urina , Instituições Acadêmicas , Índice de Gravidade de DoençaRESUMO
BACKGROUND: The ability of the host immune system to efficiently clear Plasmodium falciparum parasites during a malaria infection depends on the type of immune response mounted by the host. STUDY DESIGN: In a cross-sectional study, we investigated the cellular-and antibody responses in individuals with P. falciparum infection, in an attempt to identify immunological signs indicative of the development of natural immunity against malaria in Ibadan, Nigeria. Levels of IL-10, IL-12(p70), IFN-gamma, and IgM, IgG and IgG1-4 subclasses in the serum of 36 symptomatic children with microscopically confirmed malaria parasitaemia and 54 asymptomatic controls were analysed by ELISA. RESULTS: IFN-gamma and IL-10 were significantly higher in the symptomatic children (p=0.009, p=0.025 respectively) than in the asymptomatic controls but no differences were seen for IL-12(p70). Estimated higher ratios of IFN-gamma/IL-10 and IFN-gamma/IL-12 were also observed in the symptomatic children while the asymptomatic controls had higher IL-12/IL-10 ratio. The mean concentration levels of anti-P. falciparum IgG1, IgG2, IgG3 antibodies were statistically significantly higher in the individuals >5 years of age than <5 years while anti-P. falciparum IgG3 antibodies were notably low in <5 years category. Children <5 years had higher IgM antibodies than IgG and the expression of IgG subclasses increased with age. CONCLUSION: Taken together, malaria infection is on a delicate balance of pro- and anti-inflammatory cytokines. The higher levels of IFN-gamma seen in the symptomatic children (<6 months) may be instrumental in immune-protection against malaria by limiting parasite replication. The observed variations in immunoglobulin subclass levels were age-dependent and exposure-related.
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Anticorpos Antiprotozoários/sangue , Citocinas/imunologia , Malária Falciparum/imunologia , Plasmodium falciparum/imunologia , Adolescente , Adulto , Animais , Anticorpos Antiprotozoários/imunologia , Estudos de Casos e Controles , Criança , Pré-Escolar , Estudos Transversais , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Imunoglobulina M/imunologia , Interferon gama/sangue , Modelos Logísticos , Malária Falciparum/sangue , Malária Falciparum/parasitologia , Masculino , Nigéria , Plasmodium falciparum/genética , Adulto JovemRESUMO
BACKGROUND: Effective control and management of severe malaria cases depends on a clear understanding of the local epidemiological factors and specific clinical manifestations of the disease in the different endemic regions. OBJECTIVES: To determine the prevalence of severe malaria and epidemiological factors that affect the development of malaria anaemia. METHODS: A cross-sectional survey was carried out among children below 5 years of age, at the Adeoyo State Maternity Hospital, Ibadan, Nigeria. Questionnaires and case histories were taken from patients clinically diagnosed of malaria. Thus, 372 volunteers were recruited into the study from the 3131 paediatric cases that reported over the 10-week period to the out-patient department (OPD) of the hospital. 229 (61.6%) of the recruited volunteers presented with fever (>37.5 degrees C) at consultation. These had malaria parasite and PCV tests done. RESULTS: Clinical diagnosis was confirmed microscopically in 78% (290/372) for Plasmodium infection using thick film slides. Anaemia (PCV <28%) prevalence was 28.2%. Factors that contributed to the rapid progression of uncomplicated malaria to severe status included: age of the child, level of parasitaemia, careless response and attitude of parents or guardians to fever in the children; parents' preoccupation with their jobs or other healthy children and unwillingness to use available health facilities. CONCLUSION: The study underscores the need for community involved partnership for malaria control especially through health education for the home management of malaria, especially among those experiencing some form of inequity in access to healthcare.
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Anemia/epidemiologia , Malária/sangue , Índice de Gravidade de Doença , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Lactente , Recém-Nascido , Malária/complicações , Masculino , NigériaRESUMO
Malaria merozoite surface protein 1 (MSP1) is cleaved in an essential step during erythrocyte invasion. The responses of children to natural malaria infection included antibodies that inhibit this cleavage and others that block the binding of these inhibitory antibodies. There was no correlation between the titer of the antibody to the 19-kDa fragment of MSP1 and its inhibitory activity. These findings have implications for the design of MSP1-based vaccines.