Gustave B. Kabre

Equivalent susceptibility of Anopheles gambiae M and S molecular forms and Anopheles arabiensis to Plasmodium falciparum infection in Burkina Faso

BackgroundThe Anopheles gambiae sensu lato (s.l.) species complex in Burkina Faso consists of Anopheles arabiensis, and molecular forms M and S of Anopheles gambiae sensu stricto (s.s.). Previous studies comparing the M and S forms for level of infection with Plasmodium falciparum have yielded conflicting results.MethodsMosquito larvae were sampled from natural pools, reared to adulthood under controlled conditions, and challenged with natural P. falciparum by experimental feeding with blood from gametocyte carriers. Oocyst infection prevalence and intensity was determined one week after infection. DNA from carcasses was genotyped to identify species and molecular form.ResultsIn total, 7,400 adult mosquitoes grown from wild-caught larvae were challenged with gametocytes in 29 experimental infections spanning four transmission seasons. The overall infection prevalence averaged 40.7% for A. gambiae M form, 41.4% for A. gambiae S form, and 40.1% for A. arabiensis. There was no significant difference in infection prevalence or intensity between the three population groups. Notably, infection experiments in which the population groups were challenged in parallel on the same infective blood displayed less infection difference between population groups, while infections with less balanced composition of population groups had lower statistical power and displayed apparent differences that fluctuated more often from the null average.ConclusionThe study clearly establishes that, at the study site in Burkina Faso, there is no difference in genetic susceptibility to P. falciparum infection between three sympatric population groups of the A. gambiae s.l. complex. Feeding the mosquito groups on the same infective blood meal greatly increases statistical power. Conversely, comparison of the different mosquito groups between, rather than within, infections yields larger apparent difference between mosquito groups, resulting from lower statistical power and greater noise, and could lead to false-positive results. In making infection comparisons between population groups, it is more accurate to compare the different groups after feeding simultaneously upon the same infective blood.

Plasmodium species occurrence, temporal distribution and interaction in a child-aged population in rural Burkina Faso

BackgroundMalaria can be caused by five Plasmodium species. Due to their higher prevalence, much of the research concentrates on Plasmodium falciparum and Plasmodium vivax. In Burkina Faso, where P. falciparum co-exists with Plasmodium malariae and Plasmodium ovale, there is not much data about the prevalence of the latter two species across human population. Moreover, interactions between co-infecting Plasmodium species are not documented. The aim of the current research is to determine species-specific prevalence and temporal distribution. The potential interactions between co-infecting Plasmodium species amongst the child-aged population in Burkina Faso are also discussed.MethodsThe study took place in the Sudanese savannah zone in Burkina Faso in a rural village, Laye. Surveys were conducted during the wet season across four years, 2007 to 2010. Volunteers aged three to 15 years with parental signed consent were enrolled. Ten children per week were screened for any history of pain, fever. Parasitological data were obtained by blood slide processing.ResultsThree sympatric Plasmodium species were recorded during this study with an average prevalence of 70.7%. Species temporal distribution showed an increase of P. malariae parasite prevalence from 0.9% in 2007 to 13.2% in 2010. Within a season, P. falciparum occurred in the overall study period while P. malariae and P. ovale were highly prevalent after the rainy part of this period. Species-specific infection analysis showed that in a comparison of mono-infections, P. malariae gametocyte prevalence and median density were higher than those of P. falciparum (88.9% vs 34.5% and 124.0 vs 40.0 gametocytes/μl, respectively). Likewise, in P. falciparum co-infections with P. malariae or P. ovale, gametocyte prevalence was also higher than in P. falciparum mono-infection. However, in P. falciparum mixed infection with P. malariae, P. falciparum gametocyte prevalence and median density as well as asexual form density decreased compared to P. falciparum mono-infection while for P. malariae mono-infection, only asexual form density significantly vary.ConclusionThese data revealed high gametocyte prevalence in other Plasmodium species than P. falciparum with a significant variation of P. malariae gametocyte carriers and gametocyte density across years. Molecular tools and entomological studies are needed to highly assess species-specific contribution to malaria transmission.

Physicochemical and parasitological quality of vegetables irrigation water in Ouagadougou city, Burkina-Faso

The quality of irrigation water from different sources used by urban vegetable producers, the watered soils and vegetables in Ouagadougou was investigated. From December 2012 to December 2013, samples of water (97), lettuces heads (20), manure (10) and soil (9) were collected and analyzed for their parasitological quality using modified Bailenger methods. The result shows that parasites concentration in samples (1 to 11 egg/L in water, 0.45 egg/g on lettuce and 0.48 egg/g in soil) are above the threshold levels set by WHO/FAO for unrestricted irrigation. Different protozoa and helminthes belonging to 9 species were identified in the samples analyzed. These include Ankylostoma duodenalis, Hymenolepis nana, Ascaris lombricoides, Taenias ssp., Strongyloides stercoralis, Entamoeba histolytica, Giardia lamblia and Entamoeba coli. Despite variation in isolated parasites, eggs of A. lumbricoides and A. duodenalis were common in all water, soil and vegetables. Furthermore 14.87% of collected eggs have proven to be viable with predominance of helminthes eggs. As a result, farmers appear to be the most exposed group to helminthiasis. Key words: Waterborne parasites, vegetables, urban-farming, Ouagadougou.

Assessment of benthic molluscs diversity and distribution in urban reservoirs (Ouagadougou, Burkina Faso)

The urban reservoirs n° 2 and n°3 of Ouagadougou, located in the middle of the city are subject to multiple anthropogenic pressures which threaten the diversity of benthic macroinvertebrates community group like molluscs. This study was initiated to assess the diversity and distribution of benthic molluscs in these reservoirs. Molluscs samples were collected monthly using an Eckman grab (12 x 20 cm 2 ) between September 2011 and February 2012 in 24 sampling points defined on each reservoir. In parallel, physicochemical variables and water colon depth were measured. After sampling, molluscs were transported to the laboratory for identification. A total of 328 specimens were collected of which 5 species were identified: three species of Gastropods ( Bellamya unicolor , Cleopatra bulimoides , Lanistes ovum ) and two species of Bivalves ( Coelatura aegyptiaca , Mutela rostrata ). B. unicolor was the most abundant species with 71% of the collected molluscs and preferentially occupied the edges of the reservoir. It was followed by C. aegyptiaca (27%) which was abundant in the central axis of the reservoir. Physicochemical variables influence the distribution of species. For all measured physicochemical factors, B. unicolor was more tolerant than C. aegyptiaca on the occupation of available habitat.

Occurrence of Tetracampos ciliotheca (Cestoda: Bothriocephalidea) in the gall bladder of Clarias anguillaris in Burkina Faso

The presence of the bothriocephalidean cestode Tetracampos ciliotheca Wedl, 1861 is reported from the gall bladders of the catfish Clarias anguillaris from Loumbila and Ziga reservoirs, Burkina Faso, in 2010–2011. Of the 159 specimens examined, 47 were infected. Mean intensity of infection was 4.3 parasites per infected host, the maximum was 22 tapeworms in the gall bladder and the mean abundance was 1.3 parasites. There was no significant difference between males and females or between the two localities. There was a positive relationship between fish size and the number of parasites in the gall bladder. This study provides further evidence of the presence of T. ciliotheca in the gall bladder, in which most tapeworms found were localised. Tapeworms were also found in the stomach and intestine, with prevalences of 1% and 16%, and mean infection intensities of 1 and 5.3, respectively.