Tazoacha Asonganyi

Absence of the LiTat 1.3 (CATT antigen) gene in Trypanosoma brucei gambiense stocks from Cameroon.

Antibodies to the variable antigen type (VAT) designated LiTat 1.3 are common in sera from parasitologically confirmed patients with gambian sleeping sickness. For this reason, LiTat 1.3 has been considered a suitable antigen for detecting Trypanosoma brucei gambiense in the Card Agglutination Test for Trypanosomiasis (CATT; Testryp-CATT, Smith Kline-RIT). However, surveys in the T.b. gambiense endemic focus of Fontem in Cameroon have suggested that expression of LiTat 1.3 might be rare or absent. We show here that the gene for LiTat 1.3 was indeed absent from some T.b. gambiense stocks isolated from this focus, and a LiTat 1.3-like gene was present in others. The divergent gene differed from the cloned version of LiTat 1.3. In addition, antibodies to LiTat 1.3 could not be detected in rabbits infected with either of the two kinds of T.b. gambiense from the Fontem area. We suggest that the absence of LiTat 1.3 expression in this focus may have important implications for the epidemiology and control of sleeping sickness, especially if heavy reliance is placed on the CATT.

Microsporidian Infection Is Prevalent in Healthy People in Cameroon

ABSTRACT Most studies of opportunistic infections focus on those with weak immune systems, such as human immunodeficiency virus (HIV)/AIDS patients and children. However, there is a lack of information on these infectious agents in healthy people worldwide. In the present study, stool samples from both HIV patients and healthy people were examined to begin filling in this serious gap in the understanding of human microsporidiosis, particularly the enteric parasite Enterocytozoon bieneusi. Specimens were obtained from 191 individuals living in Yaoundé, the capital city of Cameroon, in sub-Sahara Africa, including 28 HIV-positive patients who also had tuberculosis (TB). E. bieneusi prevalence was 35.7% among the HIV+ TB patients, whereas it was only 24.0% among 25 HIV− TB patients in the same hospital. Unexpectedly, the prevalence (67.5%) of microsporidiosis was found to be even higher for 126 immunocompetent individuals than for those with TB (healthy people compared to HIV+ TB and HIV− TB patients; P < 0.001). The immunocompetent group included people ranging from 2 to 70 years of age living in four different neighborhoods in Yaoundé. The highest prevalence (81.5%) was among teenagers, and the highest mean infection score (+2.5) was among children. Additional studies of immunocompetent people in other parts of Cameroon, as well as in other countries, are needed to better understand microsporidiosis epidemiology. There is still much more to be learned about the natural history of microsporidia, the pathogenicity of different strains, and the role of enteric microsporidia as opportunistic infections in immunodeficient people.

Population genetic structure of Central African Trypanosoma brucei gambiense isolates using microsatellite DNA markers

Genetic variation of microsatellite loci is a widely used method for the analysis of population genetic structure of microorganisms. Seven microsatellite markers were used here to characterize Trypanosoma brucei gambiense isolates from Central Africa sub-region in order to improve knowledge on the population genetic structure of this subspecies. These markers confirmed the low genetic polymorphism within Central African T. b. gambiense isolates from the same focus and strong differentiation between different foci. The presence of many multilocus genotypes of T. b. gambiense and the excess of heterozygotes found in this study play in favour of a clonal reproduction of this parasite. But some data may be indicative of a unique recombination event in one subsample. The high F(ST) value indicates low migration rates between T. b. gambiense subpopulations (foci). Very negative F(IS) suggests fairly small clonal population sizes of this pathogen in the different human trypanosomosis foci of Central Africa.

Characterization of the antiproliferative activity of Xylopia aethiopica

BackgroundXylopia aethiopica, a plant found throughout West Africa, has both nutritional and medicinal uses. The present study aims to characterize the effects of extracts of this plant on cancer cells.ResultsWe report that X. aethiopica extract prepared with 70% ethanol has antiproliferative activity against a panel of cancer cell lines. The IC50 was estimated at 12 μg/ml against HCT116 colon cancer cells, 7.5 μg/ml and > 25 μg/ml against U937 and KG1a leukemia cells, respectively. Upon fractionation of the extract by HPLC, the active fraction induced DNA damage, cell cycle arrest in G1 phase and apoptotic cell death. By using NMR and mass spectrometry, we determined the structure of the active natural product in the HPLC fraction as ent-15-oxokaur-16-en-19-oic acid.ConclusionThe main cytotoxic and DNA-damaging compound in ethanolic extracts of Xylopia aethiopica is ent-15-oxokaur-16-en-19-oic acid.

Human African Trypanosomiasis Transmission, Kinshasa, Democratic Republic of Congo

To investigate the epidemiology of human African trypanosomiasis (sleeping sickness) in Kinshasa, Democratic Republic of Congo, 2 entomologic surveys were conducted in 2005. Trypanosoma brucei gambiense and human-blood meals were found in tsetse fly midguts, which suggested active disease transmission. Vector control should be used to improve human African trypanosomiasis control efforts.

Molecular diversity and polymerase gene genotypes of HIV-1 among treatment-naïve Cameroonian subjects with advanced disease

BACKGROUND The progress of antiretroviral treatment roll-out programs in developing countries requires extensive monitoring of primary drug resistance prior to initiation of therapy. This is particularly relevant for Cameroon where a high HIV diversity has been reported. OBJECTIVES To determine HIV diversity in Yaoundé, Cameroon, in a cohort of HIV-infected subjects with advanced disease. To characterize HIV-1 mutations conferring primary drug resistance and to assess primary resistance patterns in the RNase H domain of the reverse transcriptase of these viruses. STUDY DESIGN HIV-1 RNA was extracted from plasma of 59 HIV-1 infected, drug-naïve subjects with CD4+ T-cell counts<200/microl. HIV-1 pol (PR, RT and RNase H) regions were sequenced for subtyping and for identifying drug resistance mutations in pol (PR, RT and RNase H). RESULTS A complex HIV-1 diversity was seen, with multiple subtypes (A1, A2, C, D, F2, H, group O), CRFs (02_AG, 09_cpx, 11_cpx, 13_cpx, 22_01A1, 30_0206, 43_02G) and URFs. Primary drug resistance was low in PR (2%) and in RT regions (4%). RNase H mutations Q509L and Q547K were found in non-CRF02_AG strains. CONCLUSIONS A high HIV-1 diversity was already present in Cameroon in the early 90s, when the subjects were likely infected. Primary HIV-1 drug resistance was low. Occurrence of RNase H mutations with proven phenotypic effect on susceptibility to antiretrovirals encourages further assessment of their impact in treatment outcome in the context of complex HIV genetic diversity and in a subtype-specific fashion.

Evidence for high prevalence of Pneumocystis jirovecii exposure among Cameroonians.

Cameroon lacks the capacity for routine Pneumocystis pneumonia (PcP) diagnosis, thus, the prevalence of Cameroonian exposure to this microbe is unknown. It is known that Pneumocystis infecting different mammalian host species represent diverse phylogenetic backgrounds and are now designated as separate species. The highly sensitive nature of ELISA and the specificity afforded by using human-derived P. jirovecii Msg peptides has been shown to be useful for serological analysis of human sera. Thus, sera from patients in Yaoundé, the capital city of Cameroon, were analyzed for anti-P. jirovecii antibodies by enzyme-linked immunosorbent assay (ELISA) using three recombinant major surface glycoprotein (Msg) peptide fragments, MsgA1, MsgB, and MsgC1. Based on serum recognition of one or more of the three fragments, 82% of the total samples analyzed was positive for antibodies to P. jirovecii Msg, indicating high prevalence of P. jirovecii infection or colonization among Cameroonians. Different Msg fragments appear to be recognized more frequently by sera from different geographic regions of the globe. Antibodies in the Cameroonian serum samples recognized MsgA1>MsgC1>MsgB, suggesting that different P. jirovecii strains exist in different parts of the world and/or human populations differ in their response to P. jirovecii. Also, HIV(+) patients diagnosed with respiratory infections (such as TB and pneumonia) and maintained on trimethoprim/sulfamethoxazol prophylaxis had relatively lower anti-Msg titers. Whether PcP prophylaxis has significant effects on the quality of life among HIV(+) patients in Cameroon warrants further investigation.

Identification of different trypanosome species in the mid-guts of tsetse flies of the Malanga (Kimpese) sleeping sickness focus of the Democratic Republic of Congo

BackgroundThe Malanga sleeping sickness focus of the Democratic Republic of Congo has shown an epidemic evolution of disease during the last century. However, following case detection and treatment, the prevalence of the disease decreased considerably. No active survey has been undertaken in this focus for a couple of years. To understand the current epidemiological status of sleeping sickness as well as the animal African trypanosomiasis in the Malanga focus, we undertook the identification of tsetse blood meals as well as different trypanosome species in flies trapped in this focus.MethodsPyramidal traps were use to trap tsetse flies. All flies caught were identified and live flies were dissected and their mid-guts collected. Fly mid-gut was used for the molecular identification of the blood meal source, as well as for the presence of different trypanosome species.ResultsAbout 949 Glossina palpalis palpalis were trapped; 296 (31.2%) of which were dissected, 60 (20.3%) blood meals collected and 57 (19.3%) trypanosome infections identified. The infection rates were 13.4%, 5.1%, 3.5% and 0.4% for Trypanosoma congolense savannah type, Trypanosoma brucei s.l., Trypanosoma congolense forest type and Trypanosoma vivax, respectively. Three mixed infections including Trypanosoma brucei s.l. and Trypanosoma congolense savannah type, and one mixed infection of Trypanosoma vivax and Trypanosoma congolense savannah type were identified. Eleven Trypanosoma brucei gambiense infections were identified; indicating an active circulation of this trypanosome subspecies. Of all the identified blood meals, about 58.3% were identified as being taken on pigs, while 33.3% and 8.3% were from man and other mammals, respectively.ConclusionThe presence of Trypanosoma brucei in tsetse mid-guts associated with human blood meals is indicative of an active transmission of this parasite between tsetse and man. The considerable number of pig blood meals combined with the circulation of Trypanosoma brucei gambiense in this focus suggests a transmission cycle involving humans and domestic animals and could hamper eradication strategies. The various species of trypanosomes identified in the Malanga sleeping sickness focus indicates the coexistence of animal and human African Trypanosomiasis. The development of new strategies integrating control measures for human and animal trypanosomiasis may enable the reduction of the control costs in this locality.

Identification and genetic characterization of Trypanosoma congolense in domestic animals of Fontem in the South-West region of Cameroon.

To understand the circulation and the spread of Trypanosoma congolense genotypes in animals of Fontem in the southwest region of Cameroon, T. congolense forest and T. congolense savannah were investigated in 397 domestic animals in eight villages. Out of the 397 domestic animals, 86 (21.7%) were found infected by trypanosomes, using the capillary tube centrifugation test. The PCR with specific primers identified 163 (41.1%) and 81 (20.4%) animals infected by T. congolense forest and T. congolense savannah, respectively; showing for the first time the circulation of T. congolense savannah in the Fontem region. No infection with T. congolense savannah was found in pigs whereas goats and sheep were infected by T. congolense forest and/or T. congolense savannah. The prevalence of trypanosomes varied significantly amongst villages and animal species. The genotyping of T. congolense forest positive samples using microsatellites markers showed that multiple genotypes occurred in 27.2% (44/163) of animals sampled, whereas single genotypes were found in 73.8% (119/163) of samples. Some alleles were found in all animal species as well as in all villages and were responsible for major genotypes, whereas others (rare alleles) were identified only in some animals of few villages. These rare alleles were characteristic of specific genotypes, assimilated to minor genotypes which can be spread in the region through tsetse flies. The microsatellite markers show a low genetic variability and an absence of sub-structuration within T. congolense forest. The analysis of the microsatellite data revealed a predominant clonal reproduction within T. congolense forest. Pigs were the animal species with the highest number of different genotypes of T. congolense forest. They seem to play an important epidemiological role in the propagation and spread of different genotypes of T. congolense.

A new transmission risk index for human African trypanosomiasis and its application in the identification of sites of high transmission of sleeping sickness in the Fontem focus of southwest Cameroon

A new index for the risk for transmission of human African trypanosomiasis was developed from an earlier index by adding terms for the proportion of tsetse infected with Trypanosoma brucei gambiense group 1 and the contribution of animals to tsetse diet. The validity of the new index was then assessed in the Fontem focus of southwest Cameroon. Averages of 0.66 and 4.85 Glossina palpalis palpalis (Diptera: Glossinidae) were caught per trap/day at the end of one rainy season (November) and the start of the next (April), respectively. Of 1596 tsetse flies examined, 4.7% were positive for Trypanosoma brucei s.l. midgut infections and 0.6% for T. b. gambiense group 1. Among 184 bloodmeals identified, 55.1% were from pigs, 25.2% from humans, 17.6% from wild animals and 1.2% from goats. Of the meals taken from humans, 81.5% were taken at sites distant from pigsties. At the end of the rainy season, catches were low and similar between biotopes distant from and close to pigsties, but the risk for transmission was greatest at sites distant from the sties, suggesting that the presence of pigs reduced the risk to humans. At the beginning of the rainy season, catches of tsetse and risk for transmission were greatest close to the sties. In all seasons, there was a strong correlation between the old and new indices, suggesting that both can be used to estimate the level of transmission, but as the new index is the more comprehensive, it may be more accurate.