Uncomplicated falciparum malaria among schoolchildren in Bajil district of Hodeidah governorate, west of Yemen: association with anaemia and underweight.

BACKGROUND: Malaria, malnutrition and anaemia are major public health problems in Yemen, with Hodeidah being the most malaria-afflicted governorate. To address the lack of relevant studies, this study was conducted to determine the prevalence of Plasmodium falciparum and its relation to nutritional status and haematological indices among schoolchildren in Bajil district of Hodeidah governorate, west of Yemen. METHODS: A cross-sectional study was conducted among 400 schoolchildren selected randomly from four schools in Bajil district. Data about demographic characteristics, risk factors and anthropometric measurements of age, height and weight were collected. Duplicate thick and thin blood films were prepared, stained with Giemsa and examined microscopically for malaria parasites. The density of P. falciparum asexual stages was estimated on thick films. EDTA-blood samples were examined for the haematological indices of haemoglobin (Hb) and blood cell counts. RESULTS: Plasmodium falciparum was prevalent among 8.0% (32/400) of schoolchildren with a mean parasite density of 244.3 ± 299.3/µL of blood and most infections showing low-level parasitaemia, whereas Plasmodium vivax was detected in one child (0.25%). Residing near water collections was a significant independent predictor of falciparum malaria [adjusted odds ratio (AOR) = 2.6, 95.0% CI 1.20-5.72; p = 0.016] in schoolchildren. Mild anaemia was prevalent among more than half of P. falciparum-infected schoolchildren and significantly associated with falciparum malaria (AOR = 5.8, 95.0% CI 2.39-14.17; p < 0.001), with a mean Hb concentration of 10.7 ± 1.0 g/dL. Although the mean values of the total white blood cells, monocytes and platelets were significantly lower in infected than non-infected schoolchildren, they were within normal ranges. More than half of the children were malnourished, with stunting (39.3%) and underweight (36.0%) being the most prevalent forms of malnutrition; 6.3% of children were wasted. Underweight (AOR = 5.3, 95.0% CI 2.09-13.62; p < 0.001) but not stunting or wasting, was a significant predictor of falciparum malaria among schoolchildren. CONCLUSION: Asymptomatic falciparum malaria is prevalent among schoolchildren in Bajil district of Hodeidah Governorate, with predominance of low parasitaemic infections and significant association with mild anaemia and underweight. Residence near water collection is a significant predictor of infection with falciparum malaria among schoolchildren. Further studies among children with severe malaria and those with high parasite densities are recommended.

Detection of low-intensity Schistosoma mansoni infection by Percoll sedimentation and real-time PCR techniques in a low-endemicity Egyptian setting.

OBJECTIVE: To evaluate the performance of Percoll sedimentation and real-time polymerase chain reaction (PCR) for the detection of S. mansoni cases previously tested as negative by Kato-Katz technique in two low-endemic areas in Alexandria, Egypt, Abis 4 and 8 villages. METHODS: Stool samples of 824 primary schoolchildren were examined by Kato-Katz technique (three slides of 41.7 mg each). After obtaining the results of this survey, stool samples were recollected from a subset of 150 students, who gave negative results after Kato-Katz. These samples were microscopically examined after the concentration with Percoll technique. Part of the 150 negative stool samples and five positive samples (used as controls) were kept at -20 °C and further processed by SYBR Green PCR. RESULTS: Prevalence of S. mansoni infection as determined by three Kato-Katz thick smears was 1.82% (15 cases). Three more cases tested positive by Percoll sedimentation among the 150 samples that were negative by Kato-Katz. Specific amplification by SYBR Green PCR was noted in all positive controls and in three cases of Kato-Katz-negative samples, two of which were also positive by Percoll. CONCLUSION: Percoll sedimentation and SYBR Green PCR proved useful in detecting low-intensity S. mansoni infections in low-endemicity areas in Egypt.

Measuring resistant-genotype transmission of malaria parasites: challenges and prospects.

Increased gametocytemia in infections with resistant strains of Plasmodium species and their enhanced transmissibility are a matter of concern in planning and evaluating the impact of malaria control strategies. Various studies have determined weekly gametocyte carriage in response to antimalarial drugs in clinical trials. The advent of molecular biology techniques makes it easy to detect and quantify gametocytes, the stages responsible for transmission, and to detect resistant genotypes of the parasite. With the validation of molecular markers of resistance to certain antimalarial drugs, there is a need to devise a simpler formula that could be used with these epidemiological antimalarial resistance tools. Theoretical models for transmission of resistant malaria parasites are difficult to deploy in epidemiological studies. Therefore, devising a simple formula that determines the potential resistant-genotype transmission of malaria parasites should provide further insights into understanding the spread of drug resistance. The present perspective discusses gametocytogenesis in the context of antimalarial treatment and drug resistance. It also highlights the difficulties in applying the available theoretical models of drug resistance transmission and suggests Rashad's devised formula that could perhaps be used in determining potentially transmissible resistant genotypes as well as in mapping areas with high potential risk for the transmission of drug-resistant malaria. The suggested formula makes use of the data on gametocytes and resistant genotypes of malaria parasites, detected by molecular techniques in a certain geographical area within a particular point in time, to calculate the potential risk of resistant genotype transmission.

Molecular and immunological characterisation of Fasciola species.

Fasciola hepatica and F. gigantica are polymorphic liver flukes that show considerable overlap between species, and various protein separation techniques have been used as alternative means of differentiation. Acid and alkaline polyacrylamide gel electrophoresis (PAGE) show differences between F. hepatica and F. gigantica. Following SDS-PAGE, F. hepatica proteins are characterised by the presence of eight major peptide bands, with molecular weights estimated as 48, 45, 43.5, 37, 33, 29, 27 and 25.5 kDa. In contrast, F. gigantica shows only five major protein bands of 57.6, 54, 48, 29 and 27 kDa. Isoelectric focusing (IEF) demonstrates 17 bands from F. hepatica and 22 bands from F. gigantica between pH 3.5 and pH 10. Although many bands appear common to both species, some are species-specific. Six cases of human acute fascioliasis diagnosed clinically, haematologically and immunologically are also studied. Gel immunodiffusion and immunoelectrophoresis, using adult F. hepatica and F. gigantica antigens, are used to determine the species, and indicate that the antisera are more specific for F. hepatica.

A better resolution for integrating methods for monitoring Plasmodium falciparum resistance to antimalarial drugs.

Effective chemotherapy is the mainstay of malaria control. However, resistance of falciparum malaria to antimalarial drugs compromised the efforts to eliminate the disease and led to the resurgence of malaria epidemics. Three main approaches are used to monitor antimalarial drug efficacy and drug resistance; namely, in vivo trials, in vitro/ex vivo assays and molecular markers of drug resistance. Each approach has its implications of use as well as its advantages and drawbacks. Therefore, there is a need to use an integrated approach that would give the utmost effect to detect resistance as early as its emergence and to track it once spread. Such integration becomes increasingly needed in the era of artemisinin-based combination therapy as a forward action to deter resistance. The existence of regional and global networks for the standardization of methodology, provision of high quality reagents for the assessment of antimalarial drug resistance and dissemination of open-access data would help in approaching an integrated resistance surveillance system on a global scale.

Prevailing Plasmodium falciparum dihydrofolate reductase 108-asparagine in Hodeidah, Yemen: a questionable sulfadoxine-pyrimethamine partner within the artemisinin-based combination therapy.

Given that the evolution and spread of resistance to sulfadoxine-pyrimethamine (SP) have been documented at a quick pace worldwide, the present study investigated the mutant Plasmodium falciparum dihydrofolate reductase 108-asparagine (dhfr 108 N) as a key marker of resistance to the combination among parasite isolates from Hodeidah. The association of parasitologic indices with the dhfr 108 N mutant allele was also studied. Ninety patients with microscopically confirmed P. falciparum infection from Hodeidah were included in the present study. Polymerase chain reaction-restriction fragment length polymorphism approach was adopted for the molecular detection of this marker. The dhfr 108 N was detected among about 61% of P. falciparum isolates, in its pure and mixed-type forms, from Hodeidah. Age, gender and residence of patients were not significant predictors for the presence of the mutant allele among parasite isolates. In contrast, a history of malaria and antimalarial drug intake in the year preceding the study as well as frequent antimalarial drug intake were significantly associated with this mutant allele. The high frequency of dhfr 108 N among parasites isolates makes the role of SP questionable as a partner with outstanding effectiveness within the ACT, at least, in the near future. SP plus artesunate should be monitored for its antimalarial efficacy at regular intervals, preferably through the molecular detection of resistance-associated mutations.

Sulfadoxine-pyrimethamine resistance in Plasmodium falciparum: a zoomed image at the molecular level within a geographic context.

Antimalarial chemotherapy is one of the main pillars in the prevention and control of malaria. Following widespread resistance of Plasmodium falciparum to chloroquine, sulfadoxine-pyrimethamine came to the scene as an alternative to the cheap and well-tolerated chloroquine. However, widespread resistance to sulfadoxine-pyrimethamine has been documented. In vivo efficacy tests are the gold standard for assessing drug resistance and treatment failure. However, they have many disadvantages, such as influence of host immunity and drug pharmacokinetics. In vitro tests of antimalarial drug efficacy also have many technical difficulties. Molecular markers of resistance have emerged as epidemiologic tools to investigate antimalarial drug resistance even before becoming clinically evident. Mutations in P. falciparum dihydrofolate reductase and dihydrofolate synthase have been extensively studied as molecular markers for resistance to pyrimethamine and sulfadoxine, respectively. This review highlights the resistance of P. falciparum at the molecular level presenting both supporting and opposing studies on the utility of molecular markers.

Mutant Plasmodium falciparum chloroquine resistance transporter in Hodeidah, Yemen: association with parasitologic indices and treatment-seeking behaviors.

Malaria still represents a major health problem in Yemen, particularly in Hodeidah, despite continuing efforts to eliminate it. With the absence of clinically proven vaccines, chemotherapy with antimalarials is still greatly needed. Chloroquine (CQ) has been popular as the drug of choice for malaria control. However, Plasmodium falciparum resistance to CQ has been one of the main obstacles in malaria control and elimination. Although CQ is no longer the recommended antimalarial chemotherapy, it has remained the number one over-the-counter antimalarial drug in many endemic areas, including Yemen, and is still used for self-medication. In addition, promising reports on CQ efficacy reversal in many African countries brought it again into the scene. This has led to a growing interest in the possibility of its re-introduction, particularly with the concerns raised about the parasite resistance to artemisinin-based combination therapies. Therefore, the present study aimed at analyzing the CQ-associated pfcrt 76T mutation in P. falciparum isolates from patients with uncomplicated falciparum malaria in Hodeidah, west of Yemen. The association of treatment-seeking behaviors and antimalarial drug use with the pfcrt 76T mutant allele was also studied. It was revealed that there is still a sustained high frequency of this molecular marker among parasite isolates associated with younger age, decreased parasite density and the presence of gametocytes in blood. Delay in seeking treatment and frequent use of antimalarials were the behaviors significantly associated with the presence of the pfcrt 76T mutant allele among patients reporting a history of malaria treatment.

Efficacy of azithromycin, praziquantel and mirazid in treatment of cryptosporidiosis in school children.

The study was conducted at a primary school in Abis 8 village. 88 children aged eleven years consented to participate in the present study. After fecal examination, 43 (48.8%) cases were found infected with Cryptosporidium. The mean oocysts number per high power field (HPF) ranged from (1.6-48 oocysts/HPF). Azitbromycin, praziquantel (PZQ) and mirazid were given to 13, 16 and 14 infected children respectively. Three weeks after treatment, azithromycin and praziquantel gave cure rates of 91% and 56.2% respectively with a percent reduction of oocysts in stools of 99% for azithromycin and 71.5% for PZQ. Mirazid was not effective. All the three drugs were well tolerated. It was concluded that azithromycin is highly effective in the treatment of children with cryptosporidiosis: PZQ decreases the infection rate and intensity.

Antibody profile, interferon-gamma and nutritional status in cryptosporidial infection among school children.

Cryptosporidium parvum is more common in children than in adults. The host responses that induce protective immunity against Cryptosporidium is poorly understood. The present work studied the antibody profile, interferon gamma (IFN-gamma) serum level and nutritional status among infected school children, aged eleven years in a rural school in Abis 8 village. Fecal examination showed nineteen cases only infected with Cryptosporidium and ten children free from parasites (controls). The IgA, IgG and IgM serum levels in infected cases were within normal level, without significant differences as compared to controls. The IgE serum level was significantly high in infected children. The cytokine IFN-gamma was significantly lower in the infected cases as compared to controls. Malnutrition was diagnostic among infected children. It was concluded that malnutrition is the important finding related to Cryptosporidium infection. Malnutrition decreased IFN-gamma the recognized factor in protection from infection and elevated serum IgE level.