Low sensitivity of the ImmunocardSTAT® Crypto/Giardia Rapid Assay test for the detection of Giardia and Cryptosporidium in fecal samples from children living in Libreville, Central Africa.

Giardiasis and cryptosporidiosis are now recognized as neglected tropical parasitic diseases. The risk of their dissemination  in developing countries, such as Gabon, is increasing, due to urban crowding and poor sanitation. Accurate, simple and rapid diagnosis tools are thus necessary for the estimation of their real burden. The aim of this study was to evaluate the performances of the ImmunocardSTAT®Crypto/Giardia Rapid Assay test for the detection of Cryptosporidium (C.) spp. and Giardia (G.) duodenalis in children living in Libreville, Gabon. Stool samples of 173 healthy children were screened by routine microscopic using the merthiolate iodine formol concentration technique for Giardia, the modified Ziehl Neelsen (ZN) staining for Cryptosporidium and the ImmunocardSTAT® Crypto/Giardia RDT for the detection of Giardia and Cryptosporidium parasite forms and antigens respectively. G. duodenalis was detected with microscopy and the ImmunocardSTAT® Crypto/Giardia in 27 (15.6 %) and 22 (13.3 %) fecal samples respectively. C. spp. oocysts were found in 18 (10.4 %) ones, whereas only one sample was positive with the immunochromatographic assay. When microscopic examination was considered as the reference method, sensitivity and specificity of the ImmunocardSTAT® Crypto/Giardia Rapid Assay were found to be 63.0 %, 96.6 and 5.5 %, 99.3 % for G. duodenalis and C. spp. respectively. The prevalence of G. duodenalis and C. spp. carriage is high in children from Libreville. A low sensitivity of the ImmunocardSTAT® Crypto/Giardia for the detection of both parasites is observed. It is thus inappropriate as a diagnostic tool for detecting asymptomatic carriers.

Decrease of microscopic Plasmodium falciparum infection prevalence during pregnancy following IPTp-SP implementation in urban cities of Gabon.

BACKGROUND: Six years after the implementation of intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) in Gabon, its impact on placental malaria and pregnancy outcomes remains unknown. METHODS: Age, gestational data, use of IPTp-SP and birth weight were recorded during a hospital-based cross-sectional survey performed in 2011 in 387 women at the end of pregnancy. RESULTS: Malaria prevalence was 6.7 and 5.3% in peripheral and placental blood respectively. Overall, 59.0% women took at least two IPTp-SP doses which was associated with 50% reduction of Plasmodium; (P.) falciparum infection in primigravidae. Previous malaria treatment was a risk factor for peripheral P. falciparum infection, while uptake of IPTp-SP was associated with reduced parasitaemia. Anaemia prevalence was 38.0%, low birth weight and prematurity rates were 6.0 and 12.0% respectively. Young age was associated with a higher frequency of malaria, anaemia, low birth weight and preterm delivery (p<0.01). Birth weight significantly rose with increasing age (p<0.01), parity (p=0.03) and number of SP doses (p=0.03). A birth weight reduction of 230 g in case of peripheral parasitaemia (p=0.02) and of 210 g with placental parasitaemia (p=0.13) was observed. CONCLUSIONS: Microscopic P. falciparum prevalence during pregnancy significantly declined between 2005 and 2011, following IPTp-SP implementation in Gabon. Young women and paucigravidae remain the most susceptible to malaria and associated outcomes.

The relationship between microfilaraemic and amicrofilaraemic loiasis involving co-infection with Mansonella perstans and clinical symptoms in an exposed population from Gabon.

The relationship between the frequency of loiasis objective symptoms and microfilaraemic or amicrofilaraemic infection was assessed in 1148 exposed patients also infected, or not, with Mansonella perstans. Filarial infections were detected by direct microscopy, leucoconcentration and serology, with prevalence values of 39.5% Loa loa, 5.6% M. perstans and 3.4% co-infection with both filarial species. Amicrofilaraemic or occult loiasis (OL) predominated among L. loa-infected individuals, with a prevalence of 58.2%. Hypermicrofilaraemia (>8000 microfilariae (mf)/ml) was found in 18.4% of L. loa microfilaraemic patients, with 25.7% of them harbouring more than 30,000 mf/ml. Up to 34% of patients with OL showed evidence of Calabar swelling, compared with 26.3% of microfilaraemic patients (P= 0.03). Overall 5.3% of patients presented with adult worm migration across the eye, representing 16.3% of microfilaraemic individuals and 11.4% of amicrofilaraemic patients (P= 0.13). This symptom was similarly found in patients with more than 30,000 mf/ml (22%), those with microfilaraemia between 8 and 30,000 mf/ml (15.4%) and also in individuals with low or without microfilaraemia (16.1%) (P= 0.7). Five (14.3%) hypermicrofilaraemic patients did not present any L. loa-specific objective symptoms, as well as all the patients with single M. perstans infection. The presence of adult eye worm migration as a strong predictor of high microfilaraemia density would obscure the real burden of L. loa hypermicrofilaraemia in exposed individuals. For epidemiological purposes and control strategies, the mapping of L. loa in endemic areas should also take into account the group of patients with occult loiasis.

Pfcrt 76T and pfmdr1 86Y allele frequency in Plasmodium falciparum isolates and use of self-medication in a rural area of Gabon.

BACKGROUND: Studies showed that chloroquine resistance may revert to sensitivity after its withdrawal mainly detected by a significant decrease of Plasmodium falciparum pfcrt 76T and pfmdr1 86Y alleles. Besides, self-medication is considered as a key factor of antimalarial drug resistance expansion. Thus, pfcrt 76T and pfmdr1 86Y allele frequency and its relationship with antimalarial drug self-medication was analyzed in P. falciparum isolates collected in Gabon. METHODS: Samples were collected from febrile children screened for P. falciparum infection in 2005 and 2008 at the regional hospital of Oyem. Self-use of antimalarial drugs before the day of consultation was recorded. Polymorphic codons 76 and 86 of pfcrt and pfmdr1 genes were analyzed by PCR-RFLP. RESULTS: The frequency of pfcrt 76T mutant allele was greater than 70.0% in 2005 and 2008. Wild type isolates were 1.7-fold more prevalent in 2008. The prevalence of pfmdr1 86Y mutant allele was comparable between 2005 and 2008 (p=0.1); the proportion of wild type allele reached 20.5% in 2008. The frequency of wild type allele pfcrt K76 or pfmdr1 N86 was higher among patients without anti-malarial drug self-medication compared to those who used it. CONCLUSIONS: An increase of the frequency of P. falciparum wild type allele pfcrt 76K and pfmdr1 86N was observed within a short period after chloroquine withdrawal. The proportion of mutant genotypes is still high, mainly among patients using self-medication with antimalarial drugs.

Submicroscopic infections among children with adequate clinical and parasitological response (ACPR).

The aim of the study was to re-assess the treatment outcomes of Gabonese children, treated with sulfadoxine-pyrimethamine (SP) and artesunate-mefloquine (AM) and categorized by microscopy as adequate clinical and parasitological response (ACPR), using polymerase chain reaction (PCR). Dried blood spots were collected at day 0 and day 28 and stevor gene amplification was performed to detect Plasmodium falciparum infections. Plasmodial DNA was found in 27.5% (n=19/69) of the isolates collected at day 28; this proportion was 34.3% (n=12/35) in the SP group and 20.6% (n=7/34) in the AM group. This study underlines the need of an accurate and more appropriate technique such as PCR to evaluate antimalarial drug efficacy during clinical trials.

Comparative evaluation of Schistosoma mansoni, Schistosoma intercalatum, and Schistosoma haematobium alkaline phosphatase antigenicity by the alkaline phosphatase immunoassay (APIA).

To know if alkaline phosphatase (AP) from schistosomes other than Schistosoma mansoni can be used as diagnostic marker for schistosomiasis in alkaline phosphatase immunocapture assay (APIA), we comparatively tested n-butanol extracts of adult worm membranes from a Venezuelan (JL) strain of S. mansoni (Ven/AWBE/Sm); a Cameroonian (EDEN) strain of Schistosoma intercalatum (Cam/AWBE/Si) and a Yemeni strain of Schistosoma haematobium (Yem/AWBE/Sh). APIA was evaluated with sera of patients from Venezuela, Senegal, and Gabon infected with S. mansoni, from Gabon infected with S. intercalatum or S. haematobium, from Chine infected with Schistosoma japonicum and from Cambodian patients infected with Schistosoma mekongi. Results indicate that 92.5% (37/40) of Venezuela sera, 75% (15/20) of Senegal sera, 39.5% (17/43) of S. haematobium sera, and 19.2% (5/26) S. intercalatum sera were APIA-positive with the Ven/AWBE/Sm preparation. APIA with the Cam/AWBE/Si preparation showed that 53.8% of S. intercalatum-positive sera had anti-AP antibodies, and 51.2% S. haematobium-positive sera cross-immunocapturing the S. intercalatum AP. APIA performed with Yem/AWBE/Sh showed that 55.8% S. haematobium sera were positive. Only two out of nine S. japonicum sera were APIA-positive with the Ven/AWBE/Sm and Cam/AWBE/Si, and no reaction was observed with Cambodian S. mekongi-positive sera. AP activity was shown to be present in all the schistosome species/strains studied. The use of APIA as a tool to explore the APs antigenicity and the presence of Schistosoma sp. infections through the detection of anti-Schistosoma sp. AP antibodies in a host, allowed us to demonstrate the antigenicity of APs of S. mansoni, S. intercalatum, and S. haematobium.

Influence of Mansonella perstans microfilaraemia on total IgE levels in Gabonese patients co-infected with Loa loa.

Mansonella (M.) perstans filariasis is widely found in Africa, including Gabon where Loa loa is also endemic. This study reports the total IgE titres according to different bioclinical forms of single or co-infection with L. loa and M. perstans in 138 patients and 20 healthy controls. The median parasite density was significantly higher in cases of loiasis. IgE titres were higher in patients with microscopic dual-infection and in the group of patients with occult loiasis plus M. perstans microfilaraemia (8425 [5292-20,679]KUI/L and 6304 [1045-10,326]KUI/L, respectively), compared to individuals with either microfilaraemic Loa loa (3368 [1414-7074]KUI/L) or Mansonella (4370 [1478-7334]KUI/L) single infections (p<0.01). IgE levels were positively correlated with M. perstans microfilaraemia (rho=0.27; p<0.01). Compared to single infections, dual M. perstans-L. loa infection induces very high total IgE titres. Studies correlating IgE titres and clinical symptoms are needed to confirm the involvement of this immunoglobulin in the pathological processes during filariasis.

Morphometric and molecular characterizations of schistosome populations in Estuaire province Gabon.

The aim of this study was to test the hypothesis of the presence of hybrids between Schistosoma guineensis and S. haematobium in the Estuaire province (Western Gabon). Egg morphometry and single-stranded conformational polymorphism (SSCP) analysis on adult worms were used in order to characterize the schistosome populations of two sites. The morphology of the eggs showed three morphotypes: S. haematobium, S. guineensis and intermediate morphotypes, but the eggs of the morphotype S. guineensis were smaller compared to the values found in the literature. Furthermore, the SSCP analysis of the adult schistosomes showed that all the patterns corresponded to that of S. haematobium and gave evidence that hybrids were absent from our samples.

First record of Aedes albopictus in Gabon.

Aedes albopictus were collected in the French military camp of Libreville, Estuaire Province, Gabon, from January to March 2007 by human landing catches during an entomological evaluation of malaria transmission. Inspection of potential larval habitats within and outside the camp showed that Ae. albopictus was found only in artificial containers (discarded tires and small water containers). Associated species of mosquito larvae were Ae. aegypti (L.) and Culex quinquefasciatus. At the same time, Ae. albopictus adults and larvae were also collected from discarded tires in Tcheungue near Port Gentil, Ogoue Maritime Province. Ae. albopictus seems to be established in this part of Gabon's littoral. Further studies are necessary to investigate the extension of Ae. albopictus establishment throughout the country.

[Onchocerciasis in the area of Lastourville, Gabon. Clinical and entomological aspects]. / L'onchocercose dans la région de Lastourville, Gabon. Aspects cliniques et entomologiques.

The African Programme for Onchocerciasis Control (APOC) has implemented a series of surveys aimed at evaluating the long-term impact of its activities. The region of Lastourville (Gabon) is one of the selected sites for this study. A total of 886 persons was examined for skin lesions, and 459 out of them participated in detailed ocular examinations. Blackflies were collected during one year and dissected. Although the focus was found to be hypoendemic (prevalence of nodules: 7.7%), the frequency of onchodermatitis was relatively high. The lesions of the anterior segment of the eye were rare, but the prevalence of optic nerve disease, and of choroido-retinal lesions reached 5.2 and 2.7%, respectively. The annual transmission potential (2,171 infective larvae per man) was high, when compared with the results recorded in the human population. This may be due to the presence of Onchocerca spp. of animal origin in the blackflies. These results indicate that in the area of Lastourville, though regarded as the main focus of onchocerciasis in Gabon, the disease is relatively mild.

[Opportunistic diseases in HIV-infected patients at the Jeanne Ebori Foundation in Libreville, Gabon]. / Les maladies opportunistes de l'infection par le VIH a l'hôpital Fondation Jeanne Ebori de Libreville, Gabon.

The purpose of this study was to determine the frequencies of opportunistic diseases among AIDS patients at the Jeanne Ebori Foundation (JEF) in Libreville, Gabon. A total 6313 file of patients treated in the internal medicine unit between 1994 and 1998 were analyzed. Findings showed that the main diseases related to AIDS classified according to seroprevalence were as follows: purigo (100%), cerebral toxoplasmosis (100%), oral candidiaisis (88%), bacteremia (87.8%), shingles (84.6%), minor salmonelosis (72%), and tuberclosis. The main diagnoses unrelated to AIDS at the JEF according to seroprevalene were typhoid (9.4%), common pneumonia (28%), bacterial meningitis (26.3%, hepatitis B (20.0%), and malaria (14%). In addition to these diseases there were nine cases of Kaposi's sarcoma, four cases of isosporosis, two cases of cryptococcosis, two cases of herpes Varicella, one case of cryptosporidiosis, and one case of isosporosis. The incidence of opportunistic disease was high in our study and must be taken in drug procurement.

Association of a new mannose-binding lectin variant with severe malaria in Gabonese children.

Mannose-binding lectin (MBL2) variants that decrease the plasma level of the protein or encode dysfunctional proteins are frequently associated with the severity of a number of infections and autoimmune disorders. The high frequencies of these variants in most populations of the world are probably maintained by some selective advantage against widespread diseases. We found 14 new MBL2 allelic haplotypes, two of them with non-synonymous variants, by screening 136 children with uncomplicated malaria, 131 children with severe malaria and 39 older healthy schoolchildren. We also found a significant association of a novel variant with susceptibility to severe malaria (P=0.010). Increased MBL plasma levels and corresponding MBL2 genotypes were associated with lower concentration of several cytokines and chemokines in plasma of malaria patients. We suggest that malaria could have been one of the evolutionary driving forces shaping the MBL2 polymorphism in the African population.

Lactic acidosis in Gabonese children with severe malaria is unrelated to dehydration.

BACKGROUND: Hyperlactatemia is an important and common complication of severe malaria. We investigated changes in fluid compartment volumes in patients with severe malaria and control patients with the use of bioimpedence analysis. METHODS: We estimated extracellular water and total body water volumes in a total of 180 children: 56 with severe malaria, 94 with moderate malaria, 24 with respiratory tract infection, and 6 with severe diarrhea. RESULTS: There was a mean (+/-SD) decrease in total body water volume of 17+/-24 mL/kg (or 3% of total body water volume) in patients with severe malaria. This compares with a mean (+/-SD) decrease in total body water volume of 33+/-28 mL/kg (or 6% of total body water volume) in patients with severe diarrhea. There was no increase in extracellular water volume in patients with severe malaria, suggesting no significant intravascular volume depletion in patients with severe malaria. There was no relationship between lactatemia and any changes in fluid compartment volumes. CONCLUSIONS: The changes in fluid volumes that were observed are unlikely to be of physiological significance in the pathophysiology of severe malaria.

Les maladies opportunistes de l'infection par le VIH a l'hopital Fondation Jeanne Ebori de Libreville; Gabon

Dans le but de recenser en terme de frequence les differentes maladies opportunistes diagnostiquees au cours du sida a la FJE; 6313 dossiers des patients du service de medecine interne ont ete analyses de 1994 a 1998. Les resultats ont montre que parmi les principales maladies opportunistes classant pour le sida en terme de seroprevalence etaient les suivantes : le pruri go (100); les toxoplasmoses cerebrales (100); les candidoses orales (88); les bacteriemies (87;8); le zona (84;6); les salmonelloses mineures (72); les tuberculoses (53). Les principaux diagnostics non classant du sida a la FJE en terme de seroprevalence ont ete les typhoides (29;4); les pneumonies banales (28); les meningites bacteriennes (26;3); les hepatites B (20); les paludismes (14). A ces pathologies; il faut ajouter neuf cas de kaposi; quatre isosporoses; deux cryptococcoses; un herpes; une varicelle; une cryptosporidiose; une anguillulose. La frequence des maladies opportunistes est elevee dans notre etude et doit etre pris en compte dans l'approvisionnement en medicaments

Metabolic complications of severe malaria.

Metabolic complications of malaria are increasingly recognized as contributing to severe and fatal malaria. Disorders of carbohydrate metabolism, including hypoglycaemia and lactic acidosis, are amongst the most important markers of disease severity both in adults and children infected with Plasmodium falciparum. Amino acid and lipid metabolism are also altered by malaria. In adults, hypoglycaemia is associated with increased glucose turnover and quinine-induced hyperinsulinaemia, which causes increased peripheral uptake of glucose. Hypoglycaemia in children results from a combination of decreased production and/or increased peripheral uptake of glucose, due to increased anaerobic glycolysis. Patients with severe malaria should be monitored frequently for hypoglycaemia and treated rapidly with intravenous glucose if hypoglycaemia is detected. The most common aetiology of hyperlactataemia in severe malaria is probably increased anaerobic glucose metabolism, caused by generalized microvascular sequestration of parasitized erythrocytes that reduces blood flow to tissues. Several potential treatments for hyperlactataemia have been investigated, but their effect on mortality from severe malaria has not been determined.

[Pulmonary bilharziosis due to Schistosoma haematobium: pitfalls of species diagnosis. A case report from Libreville, Gabon]. / Bilharziose pulmonaire à Schistosoma haematobium: difficulté du diagnostic d'espèce. A propos d'un cas observe à Libreville.

The purpose of this report is to describe a case of pulmonary schistosomiasis treated at la Fondation Jeanne Ebori in Libreville, Gabon. This case is exceptional due to the rarity of the disease and the schistosomiasis agent involved. The patient was a 47-year-old woman who presented with recurrent right-sided pneumonia 6 months after initial hospitalization and nonspecific antimicrobial therapy. Her general status was altered by hyperthermia, right chest pain, and repetitive bouts of hemoptysia. Because etiological diagnosis could not be achieved and clinical condition was deteriorating, the decision was taken to perform exploratory thoracotomy. Based on operative findings, medial and lower lobectomy was performed. Histological examination demonstrated granulomatous inflammatory lesions due to bilharziosis. Infection was attributed to Schistosoma haematobium that is the most common agent in pulmonary localizations. However Ziehl coloration raised the possibility of involvement of Schistosoma intercalatum that has never been observed in the lung and of a hybrid species. Natural hybridization between S. haematobium and S. intercalatum and the presence of active transmission of the Schistosoma hybrid has been suspected in Gabon.

In vitro activity of amphotericin B, fluconazole and voriconazole against 162 Cryptococcus neoformans isolates from Africa and Cambodia.

In order to determine the potential role that various antifungal agents might have in the management of cryptococcosis in tropical areas, the in vitro susceptibility of Cryptococcus neoformans isolates from Africa ( n=52) and Cambodia ( n=110) to three antifungal agents (amphotericin B, fluconazole and voriconazole) were compared using the E-test method. The results of this study (i) confirm the value of the E-test for testing the in vitro susceptibility of C. neoformans towards voriconazole; (ii) provide the first evidence demonstrating good activity of amphotericin B, fluconazole and voriconazole against Cambodian isolates; and (iii) show there are differences in susceptibility between African and Asian C. neoformans isolates, with Cambodian isolates appearing less susceptible to the agents tested but with amphotericin B maintaining good activity.

Identification and specificity of a 38 kDa Loa loa antigenic fraction in sera from high-microfilaraemic Gabonese patients.

Circulating antigens isolated from sera of three high-microfilaraemic ( Loa loa) Gabonese patients were fractionated by gel filtration. A major component (38 kDa) was identified after SDS-PAGE and immunoblotting using sera of amicrofilaraemic patients with high level of antimicrofilariae Loa loa antibodies. The 38 kDa fraction was not found in the sera of parasitised patients or healthy controls. We looked for the 38 kDa antigen in the various stages of the filarial life cycle and found it in extracts of Loa loa microfilariae but not in somatic extracts of Loa loa male and female adult worms. This fraction could be used as a diagnostic marker in loiasis for amicrofilaraemic patients.

No evidence of Wolbachia endosymbiosis with Loa loa and Mansonella perstans.

Endosymbiotic Wolbachia bacteria from different filarial species, including major pathogens of humans such as Wuchereria bancrofti, Brugia malayi and Onchocerca volvulus, seem to play an important role in the development, viability and fertility of these worms. Wolbachia trigger inflammatory host responses as well as adverse reactions against standard treatment regimens and are therefore under investigation as novel treatment targets. We investigated whether Wolbachia are also endosymbiotic in Loa loa and Mansonella perstans. In both male and female adult L. loa, we found no evidence of bacteria by light or transmission electron microscopy. Furthermore, Wolbachia-specific PCR was negative in both L. loa and M. perstans microfilariae. The absence of Wolbachia in both filarial species therefore discourages the use of antibiotics as an adjunct or alternative approach to current treatment concepts for both loiasis and mansonelliasis perstans.

[Analysis of snake bite envenomations in Gabon]. / Analyse des envenimations par morsures de serpent au Gabon.

In tropical zones, snakebites are considered serious. Exotic snakes are characterised by the poisonousness of their venom and its abundance. Death is rapid in some cases and in others the sequelae are serious. Worldwide, there are more than 5 million victims per year, with 50,000 deaths registered and 400,000 amputations. The frequency and severity of snakebites in Gabon remain unknown. It is estimated that there is an average of one snakebite every 4 days, thus some 91 snakebites per year. Through a study carried out at the Libreville Hospital, we evaluated the frequency, severity, and fatality of this circumstantial pathology. A retrospective study conducted on 157 patients admitted for snakebite at the Intensive Care Unit of the Libreville Hospital was carried out between 1998 and 2001. 1.32% of all admissions were for snakebites. Signs of venom poisoning were observed in 27 patients (17%), versus 130 cases without envenomation. The majority of cases were in adults (78%) and children affected (22%) were aged mainly 6-14 years. The snakebite season usually coincided with the rainy season. During this period, 19 cases were registered. Snakebites occurred during the daytime (93%), in the fields in 20 cases (75%) or in the home courtyard (25%). The victims lived in town in 25 cases (93%). Antivenom was used in all envenomation cases, and the result was favourable in 23 cases (18%) but unfavourable in 4 (15%).