Hyperhomocysteinemia in acute Plasmodium falciparum malaria: an effect of host-parasite interaction

BACKGROUND

Plasmodium falciparum utilises the polyamine pathway, essential in proliferation and differentiation, and imposes an oxidative stress on host cell, enhancing the loss of glutathione.

METHODS

Standard hematological parameters were determined in 40 black African subjects with acute P. falciparum malaria, 30 aged 5-24 months, 5 aged 4-10 years and 5 aged 19-35 years. Plasma homocysteine, cysteine, glutathione and cysteinylglycine levels were measured by HPLC method. Twenty-eight healthy black children (15 aged 6-24 months and 13 aged 3-10 years) and 20 healthy black adults (aged 20-40 years) were also included as controls.

RESULTS

Plasma homocysteine levels were higher in all subjects with P. falciparum malaria and correlated positively with the disease severity and number of parasites, but negatively with Hb levels and patient ages. Cysteine level was found higher in all patients and markedly higher in 4-10 year old patients. Cysteinylglycine level was found lower particularly in 19-35 year old patients. Glutathione level was significantly lower in all patients.

CONCLUSIONS

The elevated level of homocysteine during acute P. falciparum infection suggests an imbalance in the folate cycle, which could be a consequence of the reduced availability of NADPH and Vit B12, caused by increased oxidative stress. This may suggest a selection for the C677T MTHFR allele, driven by P. falciparum in sub-Saharan regions. Hence Hcy level could be useful as a predictive parameter of severity, as well as of treatment efficacy.

Helicobacter pylori infection in Burkina Faso: an enigma within an enigma

BACKGROUND

In Burkina Faso, in contrast with high rates of Helicobacter pylori infection from an early age, the prevalence of H. pylori-associated diseases (ulcer and gastric cancer) is low.

AIMS

To look for the prevalence of H. pylori in healthy natives of Burkina Faso, both children and adults.

METHODS

We studied the prevalence of H. pylori infection in 258 healthy natives of Burkina Faso (70 children aged 6 months-15 years and 188 adults aged 16-65 years), using a serological screening (IgA and IgG H. pylori antibodies). All the studied subjects underwent a questionnaire regarding their life-style, socio-economic status, dietary habits and hygienic sanitary conditions. Data concerning the questionnaire were compared between H. pylori positive and negative subjects.

RESULTS

The rates of H. pylori positivity in children were significantly higher than in adults, and in adults the positivity for H. pylori infection decreased with increasing age. The comparison of the questionnaire's data between H. pylori seropositive and seronegative subjects showed that poor socio-economic status and hygienic sanitary conditions were similar in the two groups. Instead, a higher prevalence of H. pylori positivity was observed in subjects belonging to families living in close contact with sheep, because of their labour and agro-pastoral tradition (shepherds and sedentary farmers).

CONCLUSION

H. pylori infection in Burkina Faso is acquired early in life and is related not only to some yet well-known risk factors (poor socio-economic and hygienic status), but also to a close contact with sheep. The gradually decreasing H. pylori seropositivity in adult population of Burkina Faso represents an unexplained enigma, which needs further studies.

A 24-bp duplication in exon 10 of human chitotriosidase gene from the sub-Saharan to the Mediterranean area: role of parasitic diseases and environmental conditions

Human chitotriosidase (Chit) is a member of the chitinase family and it is synthesized by activated macrophages. Recently, a genetic polymorphism was found to be responsible for the common deficiency in Chit activity, frequently encountered in different populations. We analyzed the Chit gene in some ethnic groups from the Mediterranean and African areas, to evaluate whether the Chit gene polymorphism correlates with the changes in environmental features and the disappearance of parasitic diseases. We found a heterozygote frequency for the duplication of 24 bp in exon 10 of 44% in Sicily and 32.71% in Sardinia, whereas those homozygous Chit deficient were 5.45 and 3.73%, respectively. In contrast, in Benin and Burkina Faso, both mesoendemic regions for Plasmodium falciparum malaria and other infections due to intestinal parasites, a low incidence of Chit mutation was found (heterozygous 0 and 2%, respectively) and no subject was homozygous for Chit deficiency. Our results provide evidence of the fact that the low frequency or the absence of mutant Chit gene may represent a protective factor in the population still living in disadvantaged environmental conditions. The present study suggests that the disappearance of parasitic diseases and the improved environmental conditions may have ensued the occurrence of a high percentage of 24-bp mutation in Sicily, in Sardinia and in other Mediterranean countries, whereas in the sub-Saharan regions (Benin and Burkina Faso), the widespread parasitic diseases and the poor social status have contributed to maintenance of the wild-type Chit gene.

Antibiotic resistance in Burkina Faso

Burkina Faso is one of the Subsaharan African nations. No national services for monitoring of antibiotic resistance are available, so the number of reports of resistance patterns among hospital pathogens are inconsistent. In order to evaluate antibiotic resistance, a total of 1998 valuable microrganisms were analysed during 2000 at the Medical Centre St. Camille of Ouagadougou, Burkina Faso's capital. They were isolated as follows: 1012 from urine-culture, 503 from tonsil swabs, 398 from pus, 53 from sputum and 32 from blood-cultures. Escherichia coli was the most isolated microrganism from urine (44%); Enterococcus faecalis from tonsil swabs (96.4%), Staphylococcus aureus from pus (17%) and K. pneumoniae (70%) from sputum. In general, resistance to the old antibiotics, such as aminopenicillins and cotrimoxazole was shown. The most active antibiotic was norfloxacin, a rarely used antibiotic in this country. In conclusion, our study shows that it is necessary to create antibiotic-resistance surveillance centers in the developing countries to adopt an accurate therapy to avoid exporting of antibiotic resistance to the developed countries linked to increased emigration.

Modulation of immune response in Plasmodium falciparum malaria: role of IL-12, IL-18 and TGF-beta

The interaction between pro- and anti-inflammatory cytokines such as interleukin 12 (IL-12), interleukin 18 (IL-18) and transforming growth factor beta (TGF-beta) plays an important role in malaria pathogenesis and outcome, modulating the immunoresponse in Plasmodium falciparum malaria. In our previous studies, we analyzed the plasmatic levels of IL-12, IL-18 and TGF-beta in 105 African children with different degrees of malaria and we correlated the production of these cytokines with the severity of the disease. The aim of the present study was to analyze with a mathematical model, taking into account all the relationships between these cytokines and the parameter variations involved in malaria pathogenesis that influence the results of each type of treatment or therapeutic protocol on patients at different stages of the disease. A mathematical correlation was demonstrated between the levels of pro-inflammatory and anti-inflammatory cytokines, and from this it was possible to build curves of reference in which each patient was positioned based on IL-12 level. Our data, obtained in patients with mild and severe diseases, demonstrate that the levels of IL-12 represent a reliable parameter to predict the progression of the disease, which may be complemented or modulated by administration of IL-18 and TGF-beta. Our findings provide future implications for an immune therapy against the P. falciparum malaria infection, especially in the early phase of the disease showing that a more aggressive outcome may be due to the lack of a balanced immune response.

Plasma chitotriosidase activity in beta-thalassemia major: a comparative study between Sicilian and Sardinian patients

BACKGROUND

Chitotriosidase is a functional chitinase secreted by activated macrophages, which is extremely increased in plasma of patients with Gaucher disease (beta-glucocerebrosidase deficiency). Recently, we found that chitotriosidase plasma levels were increased to a variable extent in Sicilian patients with beta-thalassemia major. The aim of this study is to elucidate the possible mechanisms underlying chitotriosidase overproduction in beta-thalassemia major.

METHODS

Plasma chitotriosidase was measured in 134 patients with beta-thalassemia major (64 from Sardinia and 70 from Sicily), which are treated chronically by blood transfusions leading to systemic iron overload. They all have peripheral anemia and enormous enlargement of the reticulo-endothelial system.

RESULTS

Plasma chitotriosidase activity was found most frequently elevated among Sardinian (48.4%) than Sicilian (17.1%) patients. In either group, the highest levels of plasma chitotriosidase were observed in patients with the highest degree of iron overload, suggesting that this factor could trigger chitotriosidase overproduction.

CONCLUSIONS

The higher rate of subjects with increased plasma chitotriosidase values among Sardinian than Sicilian could be related to distinct molecular basis of beta-thalassemia and environmental features.

Effectiveness of forced rehydration and early re-feeding in the treatment of acute diarrhoea in a tropical area

BACKGROUND

The administration of oral re-hydration solution (ORS) via continuous infusion through a nasogastric (NG) tube and early refeeding facilitates delivery in hospitalised children and the return back home.

METHODS

DESIGN

the observation was made during a one-year stage in the Camillian Medical Centre (CMC) of Ouagadougou in Burkina Faso. 4,131 infants and children under 5 years old, affected by acute diarrhoea and severe dehydration (loss of weight > 10%) were studied. Those children having difficulties for oral re-hydration were hydrated by continuous infusion through naso-gastric (NG) tube; the NG tube was put in by the nurses and connected to a 500 ml bottle, in which a mixture of glucose and electrolytes was dissolved according to the formula (glucose 20 g + NaCl 3.5 g + NaHCO3 2.5 g KCl 1.5 g in 1 litre of water). The infusion rate was 20-30 drops/minute. No sedative or anti-emetic drug was given, unless in the presence of uncontrolled vomiting. At the end of infusion, flour of millet (60%), soy bean (20%), peanut butter (10%), sugar (10%) and salt (1%) was administered and continued at home or in the nearby areas available for the night.

RESULTS

After 4-5 hrs of infusion 3,717 children (90%) showed a significant gain of weight, although the weight prior to the acute event preceding hospitalisation was never reached during their stay at the CMC. Only 413 children (10%) required a longer period of forced infusion: at the end of the day, however, they were fed with this flour.

CONCLUSIONS

A simple strategy, based on a NG infusion plus an oral administration of flour has proven safe and effective in encompassing those difficulties encountered in the treatment and prevention of dehydration in developing countries where the therapy, in children affected by diarrhoea, still represents a major daily occupation.