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

BACKGROUND: Malaria 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. METHODS: The 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. RESULTS: Three 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. CONCLUSION: These 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.

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

BACKGROUND: The 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. METHODS: Mosquito 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. RESULTS: In 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. CONCLUSION: The 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.

Tick species infesting cattle in the central region of Burkina Faso: Presence of Rhipicephalus microplus less than ten years after its first identification in the Southwest part of the country.

Ticks are among the most important vectors for medical and veterinary importance in African countries, representing thus an obstacle for development and improvement of livestock production. The central part of Burkina Faso is an arid region which has a low diversity of tick species and in which Rhipicephalus microplus has been absent. This study aimed to examine ticks infesting cattle within this region, focusing on the peripheral area of Ouagadougou. Tick sampling was undertaken monthly on 30 selected cattle in the state breeding station of Loumbila, from June 2017 to February 2018. Morphological identification was carried out based on previous established keys and catalogue. A total of 1,076 ticks belonging to four genera and seven species were collected. Amblyomma variegatum (50.5%) was the most abundant species followed by Hyalomma rufipes (27.4%), Hyalomma truncatum (13.7%), Rhipicephalus decoloratus (4.5%), Hyalomma impressum (2.4%), Rhipicephalus microplus (1.5%), and Rhipicephalus sanguineus sensu lato (0.1%). The results suggested a decrease of A. variegatum and Hyalomma spp. load compared to data collected in 1996 from the same study area. Presence of R. microplus and R. decoloratus has been highlighted in the studied area for the first time. This finding highlights the relevance of regular investigations on tick species infesting livestock utilizing collaboration with different stakeholders.

Plasmodium falciparum genotypes diversity in symptomatic malaria of children living in an urban and a rural setting in Burkina Faso.

BACKGROUND: The clinical presentation of malaria, considered as the result of a complex interaction between parasite and human genetics, is described to be different between rural and urban areas. The analysis of the Plasmodium falciparum genetic diversity in children with uncomplicated malaria, living in these two different areas, may help to understand the effect of urbanization on the distribution of P. falciparum genotypes. METHODS: Isolates collected from 75 and 89 children with uncomplicated malaria infection living in a rural and an urban area of Burkina Faso, respectively, were analysed by a nested PCR amplification of msp1 and msp2 genes to compare P. falciparum diversity. RESULTS: The K1 allelic family was widespread in children living in the two sites, compared to other msp1 allelic families (frequency >90%). The MAD 20 allelic family of msp1 was more prevalent (p = 0.0001) in the urban (85.3%) than the rural area (63.2%). In the urban area, the 3D7 alleles of msp2 were more prevalent compared to FC27 alleles, with a high frequency for the 3D7 300bp allele (>30%). The multiplicity of infection was in the range of one to six in the urban area and of one to seven in the rural area. There was no difference in the frequency of multiple infections (p = 0.6): 96.0% (95% C.I: 91.6-100) in urban versus 93.1% (95%C.I: 87.6-98.6) in rural areas. The complexity of infection increased with age [p = 0.04 (rural area), p = 0.06 (urban area)]. CONCLUSION: Urban-rural area differences were observed in some allelic families (MAD20, FC27, 3D7), suggesting a probable impact of urbanization on genetic variability of P. falciparum. This should be taken into account in the implementation of malaria control measures.

[Schistosomiasis caused by Schistosoma mansoni in the Kou valley: Characterization of the transmission system and socioeconomic impact]. / Endémie bilharzienne à Schistosoma mansoni à la vallée du Kou : caractérisation du système de transmission et impact socioéconomique.

Schistosomiasis is one of the waterborne diseases which benefit from environmental and behavioral changes induced by the mobilization of surface water resources in Sahelian countries, such as Burkina Faso. Studies have established the existence of human schistosomiasis in the Kou valley, one of the oldest hydro-agricultural zones in the country. However, the role of population behavior in the transmission pattern of this disease and its socioeconomic impact in this valley are poorly understood. It is in response to these questions that this study was undertaken. The objectives of this study were to identify activities that exposed most of the Valley's population to infection by schistosomiasis, and to contribute knowledge on the consequences of this disease. The study was conducted in the cold dry season at the Kou Valley, located in the South Sudanese area of Burkina Faso. It has adopted the strategy of direct observation to examine host-parasites interactions. The study of the socioeconomic consequences of the infection has been first to identify subjects that actually carry the parasite by screening the population by the Kato-Katz method. These were then subjected to a questionnaire. Data were analyzed using Epi Info 6.4. This work has revealed six activities at risk of infection for the residents of the Valley with an increased risk of factor for rice farming, household activities and swimming. In view of these activities, women and young people seem to be most vulnerable to infection. This disease causes significant economic losses as a function of socio-professional categories of infected persons.