History Of Malaria Infection Research Articles

Survey in Iranian Malaria Blood Donation Deferral: Laboratory Evaluation in Malaria Blood Donation Deferral in the Iranian Blood Centers

Introduction: Transfusion-transmitted malaria (TTM), from a malaria infected donor, is an accidental Plasmodium infection, which is one of the concerns of blood transfusion issue in the world. Countries have adopted different strategies for donor selection and improving criteria to overcome these concerns, In the Iranian Blood Transfusion Organization (IBTO), donors who refer to blood transfusion centers after registration are screened by the physicians based on interview and examination. This prevention due to the possibility of malaria infection is called malaria donor deferral strategy.
 Methods: In this study 248 malaria blood donation deferral samples were selected and evaluated by microscopic, serological and molecular methods, after completing the questionnaire.
 Results: The results of the survey of the questionnaires showed that 30 cases were deferred from donating blood due to having a history of malaria infection. In microscopic examination, Plasmodium ring was observed in 2 samples and 2 samples were also reported as suspicious. In serological examination, 23 cases (9.27%) were reported positive. All cases were reported negative for the presence of malaria parasite DNA.
 Conclusions: The adoption of TTM prevention strategies depends on the malaria endemicity of the geographical area. According to the IBTO instructions, donors are examined and interviewed by a blood transfusion physician’s and owning to traveling or residency in endemic area or malaria infection, deferred temporary or permanently.
 Recent study reveal that the strategy of donor selection and deferral in the IBTO, with little residual risk of malaria transmitting, is sufficient to prevent the occurrence of TTM in Iran.

The prevalence of symptomatic and asymptomatic malaria and its associated factors in Debre Elias district communities, Northwest Ethiopia

BackgroundMalaria is a major cause of morbidity and mortality worldwide. According to the World Health Organization 2021 malaria report, it is considered to be endemic in 85 countries and territories. Malaria elimination programmes have also faced many challenges, such as widespread asymptomatic carriers in endemic regions, and they should be considered in malaria-control programmes in endemic areas for successful transmission interruption. This study aimed to assess the prevalence of symptomatic and asymptomatic malaria infections, and associated factors in Debre Elias district communities, Northwest Ethiopia from May to Jun 2018.MethodsA community-based cross-sectional study was conducted among selected kebeles in Debre Elias district, Amhara region, North-western Ethiopia. Multi-stage sampling technique was carried out to select representative households. A total of 440 randomly selected households were included, of which one individual per household was sampled for laboratory examination. Malaria prevalence was determined by light microscopy of stained blood films and using CareStart™ Malaria HRP2/pLDH (Pf/Pv) Combo rapid diagnostic test (RDT). A structured questionnaire was employed to collect socio-demographic data and associated risk factors. Data entry and analysis were carried out using Epi data 3.1 and SPSS version 23 software, respectively. The association between dependent and independent variables was explored by using bivariate and multivariate logistic regression analyses. Statistically significant association was declared at P-value of < 0.05.ResultsA total of 440 (333 asymptomatic and 107 symptomatic) individuals were included in this study. The overall prevalence of malaria was 5% with the majority (59.1%) of infections caused by Plasmodium falciparum. Among asymptomatic participants, 4.8% (n = 16, 95% CI = 2.6–7.3) and 4.2% (n = 14, 95% CI = 2.1–6.5) were diagnosed and confirmed by RDT and light microscopy respectively. Similarly, the prevalence of malaria among 107 symptomatic individuals was 7.5% (n = 8, 95% CI = 2.8–12.6) by either RDT or light microscopy. Utilization of insecticide-treated net (ITN), availability of ITN, house with eave, previous history of malaria infection, and family history of malaria infection were significantly associated with malaria infection (P < 0.05).ConclusionIn this study, the prevalence of asymptomatic and symptomatic malaria was moderate. Screening of both symptomatic and asymptomatic malaria in the community is very important to scale up intervention programmes.

Seroprevalence of Hepatitis B Virus Infection and Its Associated Factors Among Blood Donors in Yemen.

BackgroundIn limited-resource countries, the prevalence of hepatitis B virus (HBV) infection can be measured using data taken from blood donors. This study aimed to determine the HBV infection seroprevalence and its associated factors among blood donors in Sana’a Governorate, Yemen.MethodsA cross-sectional study was conducted on 500 people who donated blood at hospitals located in Sana’a between August and October 2016. The volunteers were aged 18–65 years old and were recruited using convenience sampling. A set of questionnaires was administered through face-to-face interviews. Blood samples from each donor were tested for hepatitis B surface antigens using enzyme-linked immunosorbent assay.ResultsThe overall seroprevalence of HBV infection in the blood donors was 2.6%. Participants with a history of dental treatment had 7.80 higher odds (95% confidence interval [CI]: 2.26, 26.71; P = 0.002) for HBV infection. Respectively, blood donors who had history of malaria infection or cupping therapy had 7.48 (95% CI: 1.75, 31.82; P = 0.010) and 7.32 (95% CI: 1.72, 30.83; P = 0.010) greater odds of HBV infection.ConclusionThe seroprevalence of HBV infection in Sana’a is lower than in other governorates in Yemen. Stakeholders could focus on a history of dental procedure, malaria infection and cupping treatment when strategising about HBV infection prevention and control among blood donors.

Knowledge and Practices about Malaria in Two Tribal Dominated Regions of Madhya Pradesh, India

Given the substantial contribution tribal population makes to the overall malaria load in the country, their role is important in the malaria elimination context. Assimilation of correct malaria preventive and care seeking behaviour among them, thereby, becomes very critical. Community level knowledge and practices regarding malaria can reflect on the extent of this assimilation. A cross-sectional survey of 482 randomly selected households was conducted in Umaria and Dindori districts of Madhya Pradesh using a semi-structured schedule to assess the community level knowledge and practices with respect to the causation, transmission, prevention and treatment of malaria. Descriptive statistics are used to determine relative frequencies and percentages. Chi-square test is used to determine the associations between the variables. Majority of the respondents (71.2%) were aware of the role of mosquitoes in the transmission of malaria. However, only 30% of the respondents reported the most characteristics symptoms of malaria, i.e., “fever with chills”. The awareness about transmission and symptoms was associated with educational status of the respondents as well as history of malaria infection. 65% of the households were using mosquito net bed and 57% burnt foliage/cow dung cakes to protect themselves from mosquitoes. Out of all the malarial cases, 61% sought treatment from government health facilities, while remaining from private facilities. Findings indicate that tribal groups generally possessed knowledge about malaria and engage in desirable behaviours for its management and control pointing towards their acceptance and assimilation of the government programme.

Socio-economic and dietary diversity characteristics are associated with anemia among pregnant women attending antenatal care services in public health centers of Kembata Tembaro Zone, Southern Ethiopia.

Anemia affects every country in the world including Ethiopia. It costs the socio‐economic developments due to its health impacts. This study was aimed to determine socio‐demographic and dietary diversity and other factors associated with anemia among pregnant women in Kembata Tembaro Zone. Institution‐based cross‐sectional study design was employed. Data were collected from 423 pregnant women. Hemoglobin level was measured by Hemocue. Pretested interviewer‐administered close‐ended questionnaire was used to collect the data. Analysis was done using SPSS for windows version 20. Descriptive and multivariate logistic regression analysis was conducted. We found that overall prevalence of anemia was 18%. Less than half (43.3%) of the respondents visited the health centers for antenatal care follow‐up at least once during their pregnancy time. Only 20.1% consumed more than five food preceding 24 hr. 59.3% of the respondents were taking iron supplements during data collection time. Anemia was significantly associated with the lowest wealth index, formal education, women's occupation, husband occupation, low dietary diversity, and inadequate intake of iron‐rich foods, history of malaria infection, maternal age, and parity. Anemia was of mild public health concern in the study area. The uptake of antenatal care service for the recommended number of visits and iron folic acid supplementation and the diet diversity was low in the pregnant women. The prevalence of anemia was mild public health concern. The early and timely uptake of iron folic acid supplementation was poor. Dietary diversity and consumption of iron‐rich foods was found to be low. Thus, community mobilization and health education to improve the uptake of the antenatal care services, increase micronutrient intake through food based and control of infections are recommended.

P3438Malaria infection and risk of incident heart failure: a nationwide cohort study

Abstract Background Malaria is a parasitic mosquito-borne infection which affects more than 219 million people worldwide each year. Recent studies have hypothesized that malaria may contribute to functional and structural changes in the myocardium, which can lead to cardiovascular disease. We therefore investigated the risk of heart failure (HF) and other cardiovascular events in individuals with a prior history of malaria infection. Methods Danish nationwide registries were used to identify patients with a history of malaria infection between January 1994 and January 2017. Patients with ischemic heart disease or HF at baseline were excluded. The population was sex and age matched with the general population in a ratio of 1:10. Information on cardiovascular risk factors and medication were assessed at time of the malaria diagnosis. Cox proportional hazards models, and a propensity score-matched model, were used to assess the risk of HF, myocardial infarction (MI) and cardiovascular death (CVD). Results A total of 3,570 malaria cases were identified (40% had plasmodium falciparum). The median age was 32 years and 57% were male. During a median follow-up time of 11 years [interquartile range 5, 17], 52 cases experienced incident HF (1.5%), 30 MI (0.9%) and 58 suffered from CVD (1.6%). In unadjusted survival analyses, malaria cases had a significantly increased risk of HF (HR 1.34 95% CI 1.01–1.79, P=0.046) but not MI (HR 0.72 95% CI 0.51–1.03, P=0.073) or CVD (HR 1.14 95% CI 0.87–1.49, P=0.34). In multivariable models adjusted for hypertension, diabetes, chronic kidney disease, vascular disease and concomitant pharmacotherapy (lipid lowering/antianginal/diuretics/betablocker), the association with HF remained significant (HR 1.40 95% CI 1.05–1.87, P=0.023). A propensity score-matched model based on 7,152 individuals (1:1 of cases and controls) also yielded a significant association with HF (HR 1.59 95% CI 1.03–2.46, P=0.036). Forest plot: Malaria and CV events Conclusion Our data indicate that individuals with a prior history of a malaria infection may have an increased risk of incident HF but not MI or CVD. This suggests that malaria, on a hypothesis-generating basis, may affect long-term cardiac function.

Magnitude of Anemia and Associated Factors among Pregnant Women Attending Antenatal Care in Public Hospitals of Ilu Abba Bora Zone, South West Ethiopia: A Cross-Sectional Study.

Background Anemia is a global public health problem affecting all population particularly pregnant women. Hence, this study assessed the magnitude of anemia and associated factors among pregnant. Methods Institution based cross-sectional study was conducted among 416 pregnant women attending antenatal clinic in three public hospitals of Ilu Aba Bora zone. The study participants were selected by proportional allocation based on the number of pregnant women that the respective health facilities contain. Semistructured questionnaire was used for data collection. Midupper arm circumference was employed to assess the nutritional status and standard mood depression assessment tool was used to assess depression. Data were centered and analyzed using SPSS version 20.0. Logistic regression analyses were used to see the association of different variables. Results In this study, 31.5% of pregnant women were anemic. In addition, having family size five and above [AOR = 2.97, 95% CI (1.69, 5.27)], being rural resident [AOR=2.74, (95%CI) (2.11, 5.06)], had a higher odds of anemia. Similarly, having soil transmitted helminthes infection [AOR= 3.19, 95% CI (1.5, 6.65)] and history of malaria infection in the last one year [AOR= 3.10, 95% CI (2.10, 5.06)] had also a higher odds anemia during pregnancy. Moreover, being undernourished [AOR= 2.74 95% CI (1.34, 5.57)] was negatively associated with magnitude of anemia. Conclusions The magnitude of anemia among pregnant women was found to be significant. Residence, family sizes, history of malaria infection during the last one year, and undernourishment were significantly associated with anemia during pregnancy.

Submicroscopic malaria cases play role in local transmission in Trenggalek district, East Java Province, Indonesia

BackgroundTrenggalek district is a hypoendemic malaria area with mainly imported cases brought by migrant workers from islands outside Java. During malaria surveillance in 2015, no malaria cases were found microscopically, but some cases were positive by PCR. Therefore, a study was conducted to prove that local malaria transmission still occur.MethodsThe adult villagers were invited to the house of the head of this village to be screened for malaria using aseptic venipuncture of 1 mL blood upon informed consent. Thin and thick blood films as well as blood spots on filter paper were made for each subject. The blood films were stained with Giemsa and the blood spots were used to extract DNA for polymerase chain reaction (PCR) amplification to determine the malaria infection. In addition, the history of malaria infection and travel to malaria endemic areas were recorded. Entomologic survey to detect the existence of anopheline vector was also conducted.ResultsOf the total 64 subjects that participated in the survey, no malaria parasites were found through microscopic examination of the blood films. The PCR analysis found six positive cases (two Plasmodium falciparum, one Plasmodium vivax and two mixed infection of both species), and two of them had no history of malaria and have never travelled to malaria endemic area. Entomologic survey using human bait trap detected the existence of Anopheles indefinitus that was found to be positive for P. vivax by PCR.ConclusionsThe results indicated that although we did not find any microscopically slide positive cases, six PCR positive subjects were found. The fact that 2 of the 6 malaria positive subjects have never travelled to malaria endemic area together with the existence of the vector confirm the occurence of local transmission of malaria in the area.

Assessment of individual and household malaria risk factors among women in a South African village

There is need to understand how various malaria risk factors interact at the individual, household and community levels, as well as wider contexts, in order to guide the design and implementation of effective and more comprehensive control strategies. Using a cross-sectional approach, this study investigated various malaria risk factors among residents of Mgedula Village, a malaria-endemic community located in Jozini Local Municipality, UMkhanyakude District, South Africa from May to August 2014. Data from 121 randomly sampled women were collected using close-ended questionnaires. The women were aged between 18 and 40 years; and had been residents in the study area for five years or more. A multivariable logistic regression model was used to measure the association between a history of malaria infection in the previous 12 months and various potential risk factors. The results showed that practicing animal husbandry (OR 20), residing in household structures that had not been sprayed (OR 16.7) and cross-border movement (OR 14.3) were greatly associated with malaria infection. Other factors that were significantly associated with this infection included illiteracy (OR 9.1), having a largely populated household (OR 6.1) and low income (OR 1.65). Individuals with a history of malaria infection were less likely to lack basic malaria-related knowledge (OR 0.58), to have negative attitude towards malaria (OR 0.29) and also to have poor malaria practices (OR 0.3). There was no association between a malaria episode and residing at a long distance from the health facility. Indoor residual spraying indicated a notable reduction of malaria risk at the community level. However, other socio-economic, geographical and socio-demographic factors interacted at different levels to increase this risk among different individuals and households. To achieve malaria elimination by the year 2018, these aspects should be considered when developing and implementing elimination strategies at the individual, household and community levels, among high-risk populations.

Reactive case-detection of malaria in Pailin Province, Western Cambodia: lessons from a year-long evaluation in a pre-elimination setting.

BackgroundAs momentum towards malaria elimination grows, strategies are being developed for scale-up in elimination settings. One prominent strategy, reactive case detection (RACD), involves screening and treating individuals living in close proximity to passively detected, or “index” cases. This study aims to use RACD to quantify Plasmodium parasitaemia in households of index cases, and identify risk factors for infection; these data could inform reactive screening approaches and identify target risk groups.MethodsThis study was conducted in the Western Cambodian province of Pailin between May 2013 and March 2014 among 440 households. Index participants/index cases (n = 270) and surrounding households (n = 110) were screened for Plasmodium infection with rapid diagnostic tests (RDT), microscopy and real-time polymerase chain reaction (PCR). Participants were interviewed to identify risk factors. A comparison group of 60 randomly-selected households was also screened, to compare infection levels of RACD and non-RACD households. In order to identify potential risk factors that would inform screening approaches and identify risk groups, multivariate logistic regression models were applied.ResultsNine infections were identified in households of index cases (RACD approach) through RDT screening of 1898 individuals (seven Plasmodium vivax, two Plasmodium falciparum); seven were afebrile. Seventeen infections were identified through PCR screening of 1596 individuals (15 P. vivax, and 22 % P. falciparum/P. vivax mixed infections). In the control group, 25 P. falciparum infections were identified through PCR screening of 237 individuals, and no P. vivax was found. Plasmodium falciparum infection was associated with fever (p = 0.013), being a member of a control household (p ≤ 0.001), having a history of malaria infection (p = 0.041), and sleeping without a mosquito net (p = 0.011). Significant predictors of P. vivax infection, as diagnosed by PCR, were fever (p = 0.058, borderline significant) and history of malaria infection (p ≤ 0.001).ConclusionThis study found that RACD identified very few secondary infections when targeting index and neighbouring households for screening. The results suggest RACD is not appropriate, where exposure to malaria occurs away from the community, and there is a high level of treatment-seeking from the private sector. Piloting RACD in a range of transmission settings would help to identify the ideal environment for feasible and effective reactive screening methods.

Soluble Human Leukocyte Antigen-G Expression in Pregnancy Success and Early Pregnancy Loss in Korle-Bu Teaching Hospital

Introduction: Human leukocyte antigen G (HLA-G) is a non-classical major histocompatibility complex (MHC) class Ib antigen characterized by a limited polymorphism. The expression of HLA-G at immune privileged sites and its ability to inhibit the effectors functions of immune cells has set HLA-G as a molecule of immune tolerance. This expression pattern is unique among HLA genes and suggests that HLA-G may be involved in interactions that are critical in establishing and/or maintaining pregnancy. Methods: Soluble HLA-G (sHLA-G) levels were measured using a BioVendor sHLA-G ELISA kit following the manufacturer’s protocol. The study participants include women undergoing spontaneous abortion, non-pregnant women, males and an archive sample of women who had normal vaginal deliveries without any complications and any history of malaria infection from gestation to delivery. Results: Soluble HLA-G levels were higher among women undergoing spontaneous abortion as compared to women who had normal vaginal delivery and non-pregnant women. Soluble HLA-G levels were also higher in second trimester as compared to first trimester in both women who had spontaneous abortions and women who had normal delivery. Conclusion: Although sHLA-G levels were higher among women undergoing spontaneous abortion as compared to non-pregnant women and women who had normal delivery, this may be playing a role in the maintenance of maternal immune tolerance to fetal antigen, since plasma sHLA-G levels increased with increasing trimester in both women who had normal delivery and women undergoing spontaneous abortion.

Long-term impact of childhood malaria infection on school performance among school children in a malaria endemic area along the Thai-Myanmar border.

BackgroundChildren represent a high-risk group for malaria worldwide. Among people in Thailand who have malaria during childhood, some may have multiple malaria attacks during their lifetime. Malaria may affect neurological cognition in children, resulting in short-term impairment of memory and language functions. However, little is known regarding the long-term effects of malaria infection on cognitive function. This study examines the long-term impact of malaria infection on school performance among school children living in a malaria-endemic area along the Thai–Myanmar border.MethodsA retrospective cohort study was conducted among school children aged 6–17 years in a primary-secondary school of a sub-district of Ratchaburi Province, Thailand. History of childhood malaria infection was obtained from the medical records of the sole malaria clinic in the area. School performance was assessed by using scores for the subjects Thai Language and Mathematics in 2014. Other variables, such as demographic characteristics, perinatal history, nutritional status, and emotional intelligence, were also documented.ResultsA total of 457 students were included, 135 (30 %) of whom had a history of uncomplicated malaria infection. About half of the malaria-infected children had suffered infection before the age of four years. The mean scores for both Mathematics and Thai Language decreased in relation to the increasing number of malaria attacks. Most students had their last malaria episode more than two years previously. The mean scores were not associated with duration since the last malaria attack. The association between malaria infection and school performance was not significant after adjusting for potential confounders, including gender, school absenteeism over a semester term, and emotional intelligence.ConclusionsThis study characterizes the long-term consequences of uncomplicated malaria disease during childhood. School performance was not associated with a history of malaria infection, considering that most students had their last malaria infection more than two years previously. These findings indicate that the impact of uncomplicated malaria infection on school performance may not be prolonged.

Into the Mist: A Rare Diagnosis for a Common Symptom

Sclerosing mesenteritis (SM) is rare condition involving fibrosis of the small bowel mesentery. The disease course is often benign but can be fatal. It most commonly presents in males with chronic abdominal pain. While the etiology remains unclear, the most common risk factors are history of abdominal surgery, trauma, or autoimmune disorders. SM is suggested by a ‘misty mesentery' sign or soft tissue mass of the mesentery noted on cross-sectional imaging, but diagnosis requires confirmation with mesenteric biopsy. Treatment includes steroids and tamoxifen, and is reserved for those who are symptomatic or have progressive disease. A 57 year old male presented with a decade of left-sided abdominal pain. The pain was initially intermittent in nature, but recently became more persistent. Medical history was remarkable for multiple prior abdominal traumas, and history of malaria infection and heat stroke. Lab workup was only notable for a mild elevation in ESR (25 mm/hr). Physical exam showed a positive Carnett sign; treatment for abdominal wall pain did not improve the patient's symptoms. Abdominal CT scan showed a “misty mesentery” sign surrounding part of the jejunum without a focal mass or pathologic lymphadenopathy. Push enteroscopy and capsule endoscopy were unremarkable. PET scan showed increased activity in the region of the “misty mesentery.” Exploratory laparotomy with biopsy of the mesentery showed fibroadipose tissue with fat necrosis and fibrosis, confirming SM. IgG4 levels were normal. Interval MRI has showed stability of disease extent and the patient has had no evidence of concomitant malignancy or autoimmune disorders. While the patient remained symptomatic, he declined therapy to date due to his concern about the side effects of steroids. This patient had multiple risk factors for SM, including his history of multiple abdominal traumas, malaria, and heat stroke. SM often causes fibrosis that envelops surrounding vasculature and can obstruct other organs including ureters and small intestine making the prognosis range from benign to potentially fatal. Surgical exploration with mesenteric biopsy should be considered for those with cross sectional imaging showing the “misty mesentery” sign in order to make the diagnosis. Our case highlights that SM, while rare, should be in the differential for a patient with chronic abdominal pain and multiple risk factors.

Prevalence and Molecular Identification of the Mediterranean Variant Among G6PD-Deficient Sistani and Balouch Males in Southeastern Iran

To determine the prevalence of G6PD deficiency and a Mediterranean mutation among males in southeastern Iran, we studied 1,097 Sistani and Balouch schoolboys. A questionnaire was used to collect demographic data and a history of malaria infection; blood samples were evaluated for G6PD deficiency and the G6PD Mediterranean mutation. Of the 1,097 boys screened, 175 were G6PD deficient (5.8 % of the Sistani boys and 19.3 % of the Balouch boys). The malaria survey indicated that among Balouch subjects, malaria infection was about 14 times that of Sistani subjects. Molecular characterization of G6PD-deficient samples revealed a general frequency of 85.1 % for the Mediterranean variant among all subjects (75 % among Sistani and 86.2 % among Balouch cases). The high prevalence of G6PD deficiency among Balouch populations confirms the hypothesis that the distribution of G6PD deficiency is concordant with the geographic distribution of malaria.

Epidemiology of malignancies in HIV patients at Kamuzu Central Hospital in Lilongwe, Malawi

Results Thus far, 315 cancer patients have been identified, with 152 (48.3%) HIV positive, 36 (11.4%) ignorant of their HIV status, and 127 (40.3%) HIV-negative (Table 1). For representation from different departments, there were 155 patients from Medicine, 62 from Surgery, 48 from Pediatrics, 32 from Gynecology, 13 from Ophthalmology, and 5 from Dental. Of the HIV-positive patients, 107 (70.4%) had Kaposi’s sarcoma, 14 (9.2%) had lymphoma, 13 (8.6%) had cervical cancer, 4 (2.6%) had breast cancer, 2 (1.3%) had esophageal cancer, 2 (1.3%) had squamous cell carcinoma of the penis, and 2 (1.3%) had conjunctival squamous cell carcinoma. More HIV patients with Kaposi’s sarcoma used tobacco and alcohol than HIV patients with other malignancies (Table 2). Among HIV-positive patients, 126 (82.9%) had a history of malaria infection, and 34 (22.4%) had a history of TB infection.

Reappraisal of Symptoms and Signs of Uncomplicated Beta Thalassemia Trait.

Although considered a mild disorder, beta thalassemia trait (uncomplicated by any other hematologic abnormality) has been reportedly associated with symptoms of anemia, while in other series hepatosplenomegaly has been reported as associated with this diagnosis. No controlled study has examined the symptoms and signs of individuals with beta thalassemia trait and compared these with age- and sex-matched normal individuals. We administered a questionnaire to 397 parents (67% females) of children with beta thalassemia major attending the National Thalassemia Centre in Kurunagala, Sri Lanka, and to 87 normal volunteers (90% females). All individuals underwent physical examination by the same investigator, as well as testing by automated cell counter (Coulter), and HPLC (Bio Rad). The mean age of the parents (33 years) and controls (29.5 years) was not significantly different. In parents with thalassemia trait, 20% of males and 42% of females complained of reduced exercise tolerance compared to 12.5% of males and 38% of females in the controls (P= NS). The questionnaire revealed that 41% of parents, and 36% of controls, complained of recurrent headache; 18% of parents, and 15% of controls, complained of lethargy (P=NS). A history of malaria infection was reported in 30% of parents with thalassemia trait, and in 24% of controls. Mean quality-of-life score, recorded formally by a linear analog scale, from 0 (poorest) to 10 (greatest) was 7.1 in parents and 7.2 in controls. Splenomegaly was detected in 6% of parents with beta thalassemia trait (mean spleen size 1.5 cm below the costal margin), and 5% of normal controls (mean spleen size 1 cm below the costal margin). These findings suggest that, by contrast to many reports in the older literature, in uncomplicated beta thalassemia trait there appears to be no symptoms or signs greater than those observed in a normal control population and that fatigue, lethargy, exercise intolerance, or splenomegaly in a patient with beta thalassemia trait should not be attributed to the underlying hemoglobinopathy.

Human recognition of T cell epitopes on the Plasmodium vivax circumsporozoite protein.

In order to identify T cell epitopes recognized by human in the Plasmodium vivax circumsporozoite protein, 28 overlapping synthetic peptides spanning the entire circumsporozoite protein were tested for their ability to stimulate proliferation of PBMC from 22 adults living in a malaria-endemic area of the Colombian Pacific Coast and from four individuals who never had a history of malaria infection. In addition, BALB/c mice were immunized with pools of peptides, and their lymph node cells were stimulated in vitro with individual peptides. Four epitopes were recognized by human lymphocytes but not all of them by mice. One of the epitopes was located inside the central repetitive B cell immunodominant domain. Several of the variants of the repeats were recognized by about one-third of the studied individuals. Another T cell epitope was located in the amino terminus and the other two in the carboxyl region. Peptides were recognized by both immune and nonimmune donors. Some of them were frequently recognized suggesting a lack of genetic restriction, whereas some others were recognized by only a few individuals but induced strong proliferation. These epitopes may be of potential value for a malaria subunit vaccine.

Limiting dilution assay for human B cells based on their activation by mutant EL4 thymoma cells: total and anti‐malaria responder B cell frequencies

The analysis of human B cell responses at the clonal level (limiting dilution assay) is still technically difficult. In the present study we report on a culture system that leads to activation, proliferation and differentiation into antibody-secreting cells (ASC) of about 90% of B cells from peripheral blood or spleen. In this system, B cells are cultured in the presence of a mutant subclone of the mouse thymoma EL4 for B cell activation and human T cell plus macrophage supernatant as source of proliferation and differentiation factors. ASC precursors generating clonal responses of IgM only, IgM plus IgG, or IgG only occurred at a ratio of about 6:3:1. The mean clone size was 380 cytoplasmic Ig+ cells; the mean amount of Ig secreted per clone was 20 ng. Furthermore, it has been found using this system that a considerable proportion of peripheral blood B cells from individuals with a history of malaria infection could generate clones of anti-malaria (Plasmodium falciparum) ASC (range of 0.1 to 1%, n = 6). In a control group of blood donors the corresponding frequencies were 10 times lower (range of 0.01 to 0.1%, n = 9). These results show that the EL4 culture system can be applied to the investigation of the human B cell specificity repertoire and of priming effects such as result from infectious disease.