Caractérisation des associations de parasites intestinaux et sanguins chez les enfants en âge scolaire dans la Région du Centre au Cameroun

Abstract

In Cameroon, since several decades, considerable efforts are made by the Ministry of Public Health to fight against malaria, Soil-transmitted helminthiasis and others parasitic tropical diseases through fighting programs against these diseases. In spite of all this, morbidity and mortality due to these diseases remain high especially in schoolchildren. The latter constitute the segment of the population most exposed to multiparasitism and its potential consequences. Many questions remain unanswered about interactions that could exist between different parasit es species in the same host during multiparasitism. Thus, the purpose of this study is to contribute to the study of the parasite interspecific relationships during multiparasitism. A cross-sectional study was conducted from September 2017 to July 2018 in the Nyong et Mfoumou Division, Centre Region of Cameroon. After obtaining ethical clearance (N°: 2018/01/968/CE/CNERSH/SP) and research authorization (N°: 894/AR/CHUY/DG/DGA/DMT), 10 surveys organized on the field allowed to randomly selected 5 public primary schools (3 in rural area and 2 in urban area) for participants recruitment. Stools samples collected in the field were analysed in the Laboratory of Parasitology, Mycology and Parasitic Immunology of the Yaoundé University Teaching Hospital by direct examination and by Formol-Ether concentration technique. Blood smears made following capillary blood samples collection on each participants, were observed after May-Grünwald-Giemsa staining technique. Parasitics associations were characterised using an exploratory model and ecological association’s index: Dice, Forbes and tetrachoric coefficient. A total of 416 participants aged from 4 to 15 (9.17 ± 0.27) years were recruited, 207 in urban and 209 in rural areas. Within the study population, 13 parasite species were identified: Plasmodium falciparum, Mansonella perstans, Loa loa, Entamoeba histolytica/dispar, Entamoeba coli, Giardia intestinalis, Endolimax nana, Blastocystis sp., Embadomonas intestinalis, Ascaris lumbricoides, Trichiuris trichiura, Hymenolepis nana and hookworms. Three hundred and nine (74.28 %) participants were infected by at least one parasite species. The infection rate by P. falciparum, main hemoparasites found, was 37.26 %. Entamoeba coli and A. lumbricoides were the mains intestinal parasite with infestation rate of 29.33 % and 21.39 % respectively. Parasitic infections rates were significantly higher in children living in rural areas and those aged between 8 to 11 years. Up to 185 (44.47 %) schoolchildren were infected by two or more parasites species, and the mean parasite richness per individual was 1.43 ± 0.01 specie per subject. The female gender (OR = 2.12, 95% CI: 1.26-3.57, P = 0.0046), age group between 8 and 11 years (OR = 1.70, 95% CI: 1.09-3.15, P = 0.0089) and rural area (OR = 0.16; 95% CI: 0.09-0.28, P = 0.0001) appeared as the main risks factors of multiparasitism of multiparasitism. Five types of parasitism were identified: monoparasitism (124 cases), biparasitism (111 cases), triparasitism (47 cases), quadriparasitism (24 cases) and pentaparasitism (03 cases). A total of 54 types of infracommunities were found with frequencies range from 0.24 % and 4.80 %: 19 types of infracommunities of 2 parasites species (26.68 %), 18 types of infracommunities of 3 parasites species ( 11.29 %), 14 types of infracommunities of 4 parasites species (5.76 %) and 3 infracommunities of 5 parasites species (0.72 %). The infracommunity with E. histolytica/dispar and P. falciparum was the most common, found in 20 (4.80 %) schoolchildren. Positive and statistically significant associations were found between species: A. lumbricoides and E. coli (P = 0.0011), E. coli and E. histolytica/dispar (P = 0.0012), E. coli and T. trichiura (P = 0.0017), T. trichiura and A. lumbricoides (P = 0.0003) and A. lumbricoides and M. perstans (P = 0.0027). D index of Dice shown middle interspecific associations between: E. coli and E. histolytica/dispar (D = 0.35), E. coli and P. falciparum = 0.35), E. histolytica/dispar and P. falciparum (D = 0.32), A. lumbricoides and T. trichiura (D = 0.42), A. lumbricoides and E. coli (D = 0.39), A. lumbricoides and P. falciparum (D = 0.27), and E. coli and T. trichiura (D = 0.41). Of all these interspecific combination, apart from those involving P. falciparum, were stronger than expected only by the chance (F > 1). According to the tetrachoric coefficient φ, there is positive correlation between: A. lumbricoides and T. trichiura (φ = 0.479), A. lumbricoides and M. perstans (φ = 0.378), A. lumbricoides and E. coli (φ = 0.404), E. coli and T. trichiura (φ = 0.450), E. coli and E. histolytica/dispar (φ = 0.323), E. coli and P. falciparum (φ = 0.138), and between E. histolytica/dispar and P. falciparum (φ = 0.148). On the other hand, there were negative correlation between: A. lumbricoides and G. intestinalis (φ = -0.318), and T. trichiura and G. intestinalis (φ = -0.498). An absence of correlation or independence found between P. falciparum and M. perstans (φ = 0.030). Our results provide a reliable database that should be used for the development and implementation of more effective health care and control strategies against multiparasitism, malaria, soil transmitted helminth and others parasitic tropical diseases in the Centre Region of Cameroon in particular and all over the country in general.