Luís Varandas

Prevalence of pfmdr1, pfcrt, pfdhfr and pfdhps mutations associated with drug resistance, in Luanda, Angola

BackgroundMalaria is the infectious disease causing the highest morbidity and mortality in Angola and due to widespread chloroquine (CQ) resistance, the country has recently changed its first-line treatment recommendations for uncomplicated malaria, from CQ to artemisinin combination therapies (ACT) in adults, and sulphadoxine/pyrimethamine (S/P) in pregnant women. Loss of SP sensitivity is, however, progressing rapidly in Africa and, in this study, were investigated a number of molecular markers associated to CQ and S/P.MethodsBlood samples were collected from 245 children with uncomplicated malaria, admitted at the Pediatric Hospital Dr. David Bernardino (HPDB), Angola, and the occurrence of mutations in Plasmodium falciparum was investigated in the pfmdr1 (N86Y) and pfcrt (K76T) genes, associated with CQ resistance, as well as in pfdhfr (C59R) and pfdhps (K540E), conferring SP resistance.ResultsThe frequencies of pfmdr1 mutations in codon 86 were 28.6% N, 61.3% Y and 10.1% mixed infections (NY). The frequency of pfcrt mutations in codon 76 were 93.9% K, 5.7% T and 0.4% mixed infections (KT). For pfdhfr the results were in codon 59, 60.6% C, 20.6% R and 18.8% mixed infections (CR). Concerning pfdhps, 6.3% of the isolates were bearers of the mutation 540E and 5.4% mixed infections (K540E).ConclusionThe results of this epidemiologic study showed high presence of CQ resistance markers while for SP a much lower prevalence was detected for the markers under study.

A randomised, double-blind, placebo-controlled clinical trial of vitamin A in severe malaria in hospitalised Mozambican children

Summary This paper reports a randomised, double-blind, placebo-controlled clinical trial of the effect of routine vitamin A supplementation given on admission to children with severe malaria with regard to survival, recovery during hospitalisation and outcome 6 weeks after discharge. Children aged between 6 and 72 months admitted to the paediatric wards of the Central Hospital of Maputo (CHM), Mozambique with a diagnosis of severe malaria were randomly assigned either to a control group (placebo) or an experimental group (vitamin A) and were followed up 6 weeks after discharge. There were 280 children in the experimental and 290 in the placebo group. Seven (2.5%) and 13 (4.5%) children died in the experimental and the placebo groups, respectively, a relative risk of death of 0.56 (95% CI 0.23–1.38, p = 0.201). During the 1st 5 hours of admission, the relative risk of death in the vitamin A-supplemented group was 2.54 (0.50–12.96); after 5 hours of admission it was 0.19 (95% CI 0.04–0. 85; p = 0.015). In the supplemented group, 4/82 (4.9%) of the children developed neurological sequelae vs 2/78 (2.6%) in the placebo group (RR= 1. 90; 95% CI 0.36–10. 09; p = 0.682). Although the overall reduction in the risk of death observed for all children receiving vitamin A is not statistically significant, it might be clinically important. This finding cannot, however, be accepted as a firm conclusion and requires validation by future trials.

A randomized double-blind placebo-controlled clinical trial of vitamin A in Mozambican children hospitalized with non-measles acute lower respiratory tract infections.

Summary objective The objective of this study was to test the potential of routine vitamin A supplementation at admission to speed up recovery during hospitalization for acute lower respiratory tract infections (ALRI) and to decrease the levels of morbidity at 6 weeks after discharge. The study was conducted in the Central Hospital of Maputo (CHM), Mozambique, from 1995 to 1997.

Community-Associated Methicillin-Resistant Staphylococcus aureus Lacking PVL, as a Cause of Severe Invasive Infection Treated with Linezolid

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging public health problem worldwide. Severe invasive infections have been described, mostly associated with the presence of Panton-Valentine leukocidin (PVL). In Portugal limited information exists regarding CA-MRSA infections. In this study we describe the case of a previously healthy 12-year-old female, sport athlete, who presented to the hospital with acetabulofemoral septic arthritis, myositis, fasciitis, acetabulum osteomyelitis, and pneumonia. The MRSA isolated from blood and synovial fluid was PVL negative and staphylococcal enterotoxin type P (SEP) and type L (SEL) positive, with a vancomycin MIC of 1.0 mg/L and resistant to clindamycin and ciprofloxacin. The patient was submitted to multiple surgical drainages and started on vancomycin, rifampicin, and gentamycin. Due to persistence of fever and no microbiological clearance, linezolid was started with improvement. This is one of the few reported cases of severe invasive infection caused by CA-MRSA in Portugal, which was successfully treated with linezolid. In spite of the severity of infection, the MRSA isolate did not produce PVL.

Linezolid in the treatment of multidrug-resistant/extensively drug-resistant tuberculosis in paediatric patients: experience of a paediatric infectious diseases unit.

Abstract Linezolid has been used in the treatment of multidrug-resistant/extensively drug-resistant tuberculosis in adults with encouraging results, however experience in children is scarce. We describe our experience with the use of linezolid as part of a multidrug regimen in the treatment of 4 patients who had persistent positive cultures, despite prolonged combined therapy.

Detection of atovaquone-proguanil resistance conferring mutations in Plasmodium falciparum cytochrome b gene in Luanda, Angola

BackgroundThe fixed dose combination atovaquone-proguanil is a recently introduced antimalarial for treatment and prophylaxis of Plasmodium falciparum malaria. It is highly effective with a good tolerability profile and a convenient prophylactic regimen. Nevertheless, cases of treatment failure have already been reported, which have been associated to mutations in the cytochrome b gene of the Plasmodium (pfcytb). The presence of atovaquone-proguanil in vivo resistance conferring mutations in pfcytb gene in Luanda, Angola, was investigated, in order to make recommendations on prescribing this antimalarial as prophylaxis for travellers.MethodsTwo hundred and forty nine blood samples from children hospitalized at Luanda Pediatric Hospital for malaria were studied. The PCR-RFLP methodology was used in order to identify pfcytb wild type codon 268 and two point mutations: T802A and A803C.ResultsAll samples were identified as wild type for pfcytb gene at codon 268. In the studied population, no mutations associated to atovaquone-proguanil treatment failure were found. Prevalence of the studied mutations in the region was estimated to be less than 0.77% (99% significance level).ConclusionAtovaquone-proguanil can be recommended for use by travellers to Luanda with expected high efficacy. This represents an improvement compared to other currently used prophylatic antimalarials in this region. However, it is imperative to continue surveillance.

Polymorphisms in Plasmodium falciparum K13-Propeller in Angola and Mozambique after the Introduction of the ACTs

We report the presence of SNPs in Plasmodium falciparum K13-propeller gene in two African countries, Angola and Mozambique, where malaria is a serious public health problem. Samples were collected before and after ACT introduction as first-line treatment. In each country 50 samples collected before and 50 after ACT introduction were analysed. A total of three different mutations (R471R and R575R in Angola and V494I in Mozambique) were identified in five samples, all collected after the introduction of ACT. The R471R mutation detected in Angola has already been reported in Africa (DR-Congo and Gabon). However, the mutations R575R (Angola) and V494I (Mozambique), have never been reported. V494I is adjacent to the known K13 resistance-associated mutation Y493H, although functional analysis did not predict a deleterious effect on protein function.

SLC40A1 Q248H allele frequencies and associated SLC40A1 haplotypes in three West African population samples

Background: Ferroportin is a transmembrane protein responsible for iron export from enterocytes and macrophages. Mutation c.744G → T (Q248H), located in exon 6 of the ferroportin gene SLC40A1, is found as a polymorphism in populations of African origin. This mutation has been extensively analysed in African-Americans, but poorly studied in native African populations. Aim: To increase information about Q248H mutation frequency in native sub-Saharan populations examining three West African populations. Subjects and methods: Samples from S. Tomé e Príncipe (n = 115), Angola (n = 156) and Republic of Guinea (n = 170) were analysed for Q248H mutation and for two polymorphisms, IVS1( − 24)G → C and microsatellite (CGG)n, using standard molecular methodology. Results: The estimated frequencies of Q248H allele were 2.2% in S. Tomé e Príncipe, 3.5% in Angola and 4.1% in Republic of Guinea. Analysis of polymorphisms IVS1( − 24)G → C and (CGG)n showed mutation allele c.744T to be strongly associated with haplotype IVS1( − 24)G/(CGG)7. Conclusions: This study confirmed the presence of Q248H mutation at polymorphic frequencies in three native sub-Saharan populations. Analysis of two additional markers in the same gene support a single origin of the mutant allele c.744T in the haplotype background IVS1( − 24)G/(CGG)7.

Plasmodium falciparum infection in pregnant women attending antenatal care in Luanda, Angola

INTRODUCTION Malaria during pregnancy remains a serious public health problem. The aim of this study was to establish the prevalence and possible risk factors for malaria in pregnant women attending antenatal care at Augusto Ngangula Specialized General Hospital in Luanda, Angola. METHODS Pregnant women (679 total) who attended antenatal care from April to September 2008 were included in the study after signing informed consent. For each participant, the social-demographic profile and malaria and obstetric histories were investigated via a questionnaire. Diagnosis was made by optic microscopy, and hemoglobin concentration measured. The associations between age, parity, gestational age, residence, schooling, malaria during gravity, anemia and treatment with incidence of Plasmodium falciparum infection were analyzed through logistic regression. RESULTS During the period of study, 74 (10.9%) out of 679 women were infected by P. falciparum. The average concentration of hemoglobin was 11.1 ± 0.07 g/dL, and there were significant associations between the history of malaria during pregnancy, P. falciparum infection (p<0.01) and anemia at the time of observation (p<0.001). CONCLUSIONS Previous history of malaria during pregnancy represents a risk factor for current infection and anemia was an important complication associated with malaria, even in women who were treated with sulfadoxine-pyrimethamine during pregnancy.

Prevalence and risk factors of Plasmodium falciparum infections in pregnant women of Luanda, Angola.

Pregnant women are at increased risk of malaria, but in Angola, epidemiologic data from this group is almost inexistent. We conducted a cross‐sectional study to determine the prevalence and risk factors of Plasmodium falciparum infections in 567 pregnant Angolan women living in Luanda province. One in five women had P. falciparum at delivery, diagnosed by PCR assay. Age, residence and history of malaria during pregnancy were significantly associated with P. falciparum infection, but gravidity and use of anti‐malarial drugs were not. Placental infections were significantly more common in women ≤18 years old and in primigravidae, but we could not correlate placental infections with poor pregnancy outcomes. These findings are relevant to malaria control policies in Luanda, Angola.