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Biomedical subjects

M Kombila

Publications and source records attributed to M Kombila.

At least 19 recordsLinked to original sources
PubMed1999

In vitro susceptibility of African isolates of Plasmodium falciparum from Gabon to pyronaridine.

The in vitro activity of pyronaridine was evaluated against 62 isolates of Plasmodium falciparum from Libreville, Gabon using an isotopic, drug susceptibility microtest and was compared with amodiaquine, chloroquine, quinine, and halofantrine activities. The mean 50% inhibitory concentration (IC50) values of the 62 isolates from Gabon to pyronaridine was 3.0 nM (95% confidence interval [CI] = 2.1-3.9). Pyronaridine was less potent against chloroquine-resistant isolates than chloroquine-susceptible isolates but more potent than chloroquine against chloroquine-resistant parasites. The cut-off value for in vitro reduced susceptibility to pyronaridine was an IC50 > 15 nM. Two isolates (3%) showed an IC50 > 15 nM. A significant positive correlation was found between the activities of pyronaridine and chloroquine (r2 = 0.26, P < 0.001), pyronaridine and quinine (r2 = 0.36, P < 0.001), pyronaridine and amodiaquine (r2 = 0.55, P < 0.001), and pyronaridine and halofantrine (r2 = 0.50, P < 0.001). This correlation suggests in vitro cross-resistance or at least in vitro cross-susceptibility, which is not necessarily predictive of cross-resistance in vivo. The present in vitro findings require comparison with those of clinical studies.

Adolescent↗
PubMed1999

[In vitro sensitivity of Plasmodium falciparum isolates from Gabon to chloroquine and cycloguanil].

The in vitro susceptibility of 91 Plasmodium falciparum isolates obtained from malaria-infected children living near Libreville (Gabon) was evaluated against chloroquine and cycloguanil (biologically active metabolite of proguanil), using an isotopic micro-drug susceptibility test. In vitro resistance to chloroquine and cycloguanil was observed in 83% (35/42) and in 38% (30/78) of the patients, respectively. Our data showed that 41% (16/39) of Gabonese field isolates were resistant both to chloroquine and cycloguanil. These findings are of great importance because they might indicate imminent chloroquine-proguanil failure, and there are not many affordable antimalarial drugs to replace chloroquine-proguanil combination.

Adolescent↗
PubMed1999

[Salmonellosis in HIV infection in a hospital setting in Gabon].

A case-control study was carried out in Libreville, Gabon, to determine the incidence of salmonella infection in HIV patients and identify any special clinical, therapeutic, or prognostic features. The records of 3000 patients hospitalized in the Infectious Disease Department of the Jeanne Ebori Foundation between January 1990 and December 1994 were studied. The incidence of salmonella infection, serotype, clinical presentation, prognostic factors and therapeutic modalities were compared in 2759 HIV-positive patients and 441 HIV-negative patients. Salmonella infection was noted in a total of 208 patients (58 HIV-positive and 150 HIV-negative). The incidence of salmonella infection was 13 p. 100 (non-typhoid in 76 p. 100 of cases) in HIV-positive patients versus 5.4 p. 100 in HIV-negative patients. The predominant serotypes in HIV-positive patients were Salmonella typhimurium and Salmonella enteritidis which accounted 41 p. 100 and 26 p. 100 of the isolated strains. The only significantly difference in clinical presentation was a higher incidence of bacteremia (84 p. 100) and focal lesions (11.4 p. 100) in HIV-positive patients with low-grade salmonella infection. The duration of treatment was three weeks with cotrimoxazole and 10 days with fluoroquinolones and cephalosporines. The outcome in HIV-positive patients was recurrence-free cure in 40 p. 100, multiple relapses in 12 p. 100, and death in 24 p. 100. The remaining patients were lost from follow-up. This study demonstrates the gravity of low-grade salmonella infection in African HIV-positive patients. Early diagnosis is necessary to allow chemotherapy which can be effective despite immunodeficiency.

Adolescent↗
PubMed1998

In vitro susceptibility of Gabonese wild isolates of Plasmodium falciparum to artemether, and comparison with chloroquine, quinine, halofantrine and amodiaquine.

The in vitro activity of artemether against 63 African isolates of Plasmodium falciparum from Libreville, Gabon was evaluated using an isotopic drug susceptibility semi-microtest. The 50% inhibitory concentration (IC50) values for artemether were in a narrow range from 0.8 to 34.8 nM (mean IC50 5.0 nM) and the 95% confidence interval (CI95%) was 3.6-6.3 nM. In vitro decreased susceptibility or resistance were observed with artemether (14%), to chloroquine (90%), to quinine (32%). Isolate susceptibility to amodiaquine and halofantrine was high i.e. 100% and 98%, respectively. There was a significant positive correlation between responses to artemether and amodiaquine (r2 = 0.45, P < 0.001), artemether and chloroquine (r2 = 0.36, P < 0.001), artemether and quinine (r2 = 0.31, P < 0.001), and artemether and halofantrine (r2 = 0.19, P < 0.01). Positive correlation between these drugs suggests in vitro cross-resistance or at least common features in drug uptake and/or mode of action or resistance.

Adolescent↗
PubMed1998

Short- and long-term action of multiple doses of ivermectin on loiasis microfilaremia.

One hundred nine Gabonese patients infected with Loa loa microfilariae were treated with ivermectin (200 microg/kg of body weight) at the Parasitology, Mycology and Tropical Medicine Department (Faculte de Medecine et des Sciences de la Sante, Libreville, Gabon). Each was given one dose per month for six consecutive months. The peripheral blood microfilaria (mf) count before and after each dose showed an average decrease in the microfilaremia of 87.3% (short-term-single dose). An annual single-dose mass treatment with 200 microg/kg of ivermectin was sufficient to control the parasite in populations with low (< 400/ml) L. loa mf counts. One month after the sixth dose (short-term-multiple doses), the average microfilaremia rate had decreased by 99.2% compared with the initial infection (35 patients). Samples were taken from 28 patients one month after the first dose and one month after the sixth dose. The average mf count decreased by 96.4% after the first dose and by 99.6% after the sixth dose (average residual mf counts = 13.7 and 1.5 mf/ml, respectively). The mf count after the sixth dose was only 11.2% of the count after the first dose. The low mf count persisted for more than six months after the sixth treatment (long-term-multiple doses). Thus, mass treatment with multiple doses is more appropriate for areas where the blood mf count is very high. These results show that the number of the annual treatments used in mass chemotherapy with ivermectin can be adapted to each population to provide efficient protection.

Adolescent↗
PubMed1997

Light microscopic changes in Plasmodium falciparum from Gabonese children treated with artemether.

The changes in Plasmodium falciparum in four Gabonese children suffering from severe malaria and treated with pure artemether were observed in thin blood smears fixed and stained with Giemsa and examined by light microscopy. Peripheral blood samples were taken every 8 hr up to 72 hr from three children and every 3 hr up to 9 hr from the other child. The morphologic changes involved all development stages (trophozoites, schizonts, and gametocytes); they were first seen 3 hr after the start of treatment and all parasites were abnormal after 24 hr. After two days of treatment, all infected erythrocytes disappeared except for a few with necrotic trophozoites. The morphologic changes were similar to the ultrastructural changes previously described in vivo and in vitro in experimental models. They confirm the rapid effect of artemisinin derivatives on parasite clearance and clinical recovery, particularly in cases of cerebral malaria.

Animals↗
PubMed1997

[Aspects of malaria in the hospitalized child in Gabon].

To gain insight into the impact of malaria on children in terms of frequency and severity, a study was carried out in a department of the Owendo Children's Hospital in Libreville, Gabon, a fully endemic area. Diagnosis of Plasmodium falciparum malaria was confirmed by blood smears in 295 of the 1592 children admitted in 1992, i.e. 18.5% of admissions. Malaria was therefore the primary cause of hospitalization. Of 122 deaths observed during the study period 9 were due to malaria-associated complications for an overall mortality rate of 7.4% and malaria-related mortality rate of 3.1%. These rates are low in comparison with those reported by other departments in Central Africa. Convulsions were observed in 30.5% of children in the department and malaria was the underlying cause of convulsions in 62.9% of these cases. Severe anemia (< 5 g/dl) was noted in 23.7% of children overall and was associated with malaria in 54.7%. Severe malaria as defined by the criteria of the World Health Organization was observed in 33.2% of children. These findings illustrate the extent of the impact of endemic malaria on children in Gabon and emphasize the need to promote malaria control programs and improve treatment.

Age Distribution↗
PubMed1996

Detection of circulating antigens in Gabonese patients with Loa loa filariasis.

Circulating antigens were detected in sera of Gabonese patients with Loa loa filarial infection by co-electrosyneresis (Co-ES). The serum samples selected for this study were exposed to rabbit hyperimmune antifilarial antisera and human immune antisera: specific arcs were observed in 35/60 filarial patients, of whom 24/47 were microfilaraemic and 11/13 amicofilaraemic. The identity of rabbit hyperimmune antisera and loiasial immune sera was confirmed by the continuity of precipitation arcs. These preliminary studies were carried out to develop diagnostic tools for loiasis and to study the physiopathology of immune complexes.

Animals↗
PubMed1995

Hepatitis B, C, D, and E markers in rural equatorial African villages (Gabon).

Serologic markers of hepatitis B virus (HBV), including HBV DNA, and of hepatitis delta virus were measured in three villages in Gabon. Of 303 subjects studied, 19% were carriers of hepatitis B surface antigen (HBsAg); 8.5% of these had anti-delta antibodies. No difference among the three villages was observed. All HBV DNA carriers were children less than 11 years of age. In the 2-9-year-old group, 71% of the HBsAg-positive children tested were HBV DNA carriers. These results indicate that HBV prevalence is high in Gabon and emphasize the importance of horizontal transmission of HBV in Africa. Antibodies to hepatitis C virus, assessed in one of the three villages, were found with a prevalence of 35% with a second generation enzyme-linked immunosorbent assay (ELISA) and 24% with a third generation ELISA. None of 35 subjects tested for antibodies to hepatitis E virus was positive.

Adolescent↗
PubMed1995

[Variation of cholostase enzymes (5'-nucleotidase and alkaline phosphatase) during a specific treatment for malaria in the Gabonese child].

Biological variations of 5'nucleotidase (5'NU) and alkaline phosphatase (AP) in 102 Gabonese children with malaria features (MF) and malaria infection (MI) receiving treatment are reported. [formula: see text] During the therapeutic assay, 5'NU rate decreases faster than AP'S; Fourteen days after the beginning of treatment, difference between AP MF and AP M1 is still significant. Enzymes decrease is an indication of the malaria drugs tolerance (MSP (*)).

5'-Nucleotidase↗
PubMed1994

Nontyphoidal salmonellal septicemia in Gabonese children infected with Schistosoma intercalatum.

Relapses of enteric fever induced by Schistosoma intercalatum have been observed to occur in central Africa. In Libreville, Gabon, 70 children (ages, 2.1-15.9 years) who were seronegative for human immunodeficiency virus and were hospitalized for septicemic salmonellosis underwent rectal biopsy for diagnosis of S. intercalatum infection. A nontyphoidal Salmonella species was isolated from 53 of the 70 patients: Salmonella typhimurium in 14 cases; Salmonella enteritidis in 7 cases; Salmonella galiema in 4 cases; Salmonella arizonae in 3 cases; and other species in 25 cases. Schistosomal eggs were present in the rectal mucosa of 48 (90.6%) of these 53 patients, in 11 (64.7%) of 17 patients with septicemia due to Salmonella typhi or Salmonella paratyphi, and in 21 (38.2%; P < .001) of 55 controls. Clinical symptoms were not different among patients coinfected with S. intercalatum and nontyphoidal Salmonella vs. those with enteric fever. Treatment with antibiotics induced apyrexia only after administration of antiparasitic therapy in 30 patients. These data strongly suggest interactions between S. intercalatum and Salmonella in infected children with clinically severe nontyphoidal salmonellal septicemia.

Adolescent↗
PubMed1994

Evaluation of Onchocerca volvulus-specific IgG4 subclass serology as an index of onchocerciasis transmission potential of three Gabonese villages.

The major objective of this study was to evaluate the usefulness of IgG4 ELISA and Western blot analysis, using a crude extract of Onchocerca volvulus adult worms as antigens, for diagnosing onchocerciasis in a Gabonese paediatric population with mixed filarial infections. The subjects had loaisis, streptocercosis or mansonellosis in addition to onchocerciasis. Control sera from loaisis or mansonellosis subjects residing outside the endemic zone were used to provide the cut-off point for positive results. The IgG4 ELISA had a specificity of 96% but a lower sensitivity of 78.7%. It detected 25 onchocerciasis cases out of 65 individuals who were negative on parasitological examination. Furthermore, the ELISA provided a more accurate picture of onchocerciasis transmission in a village with very low skin microfilarial load. A 27.5-kD antigen was identified on Western blots as a marker of onchocerciasis. The paediatric population provided a reliable window for assessing the parasitologic and serologic parameters in the three villages with disparate levels of onchocerciasis transmission.

Adolescent↗
PubMed1993

[Bilharziasis caused by Schistosoma intercalatum, a recent and forgotten form of schistosomiasis].

Schistosoma intercalatum schistosomiasis is confined to the western regions of equatorial Africa. It is often asymptomatic but it produces microscopic lesions in the intestine (mainly the rectum), the liver and the genital organs of both men and women, the latter lesions being more insidious and insufficiently explored. Its treatment, like that of other schistosomiases, consists of one course of praziquantel. Naturally, S. intercalatum may be hybridized with S. haematobium in Gabon and Cameroun which are the two countries where the two parasites coexist.

Animals↗