ABSTRACT
Aims: Intestinal parasitic infections are persistent in Africa, and we questioned here whether prevention measures imposed by the occurrence of the COVID-19 pandemic in 2020 could alleviate this threat in lowlands of the city of Yaoundé, Cameroon. Study Design: We monitored the trend of intestinal parasites in human and environmental samples from the seven subdivisions of the city of Yaounde, before (November-December 2019) and during (July-August 2020, November-December 2020) the COVID-19 pandemic. Methodology: Parasitological analysis were performed to check for the presence of helminths and protozoans in stools from inhabitants as well as in water, soil and fresh vegetables, using standard Kato Katz and Formol Ether methods.The minimum effective sample size considered for the estimation of parasite richness, parasite infection and contamination indexeswas 30 for human and 30 for environmental samples (i.e. soils, water and vegetables) per location. Results: Of the 19 parasite species identified in human and the environments, twelve were helminths and seven protozoans. The overall parasite species richness reached 16 in 2019 (12 helminths and 4 protozoans) and 19 in 2020 (12 helminths and 7 protozoans), with about 62.5-68.4% of species shared by human and environments. The parasite frequencies in human (21.03%) and water/soils (32.3%) in 2019 did not differ statistically with those of 2020 (14.6-20.3% and 10.8-35.4%, respectively). The contamination rate of vegetables (i.e. carrots, lettuce, basil, celery, etc.) has increased from 2019 (6.1-9.1%) to 2020 (9.1-24.2%), and was frequently due to roundworms, hookworms, Entamoeba and Cryptosporidium cysts. The findings suggest persistent risk associated with intestinal parasite irrespective to measures imposed by COVID-19 in study locations. Conclusion: The current control approaches may therefore integrateecological epidemiology of the intestinal parasite infections as complementary strategy in African cities.
ABSTRACT
Background: Vector control of Malaria is mainly made by using impregnated bed nets and insecticides pulverizations indoor or/and outdoor. Besides, appearance and development of resistance抯 phenomenon among mosquito populations to insecticides, constitute a significant obstacle this fighting. Aims: To highlighting a neutralization phenomenon of three insecticides (methyl-parathion, dimethoate and cypermethrin) during development of the Anopheles gambiae s.s. larvae. Methodology: Two setups followed one after the other were designed. In setup 1, four concentrations (with four replicates each) were freshly prepared and independently received a first batch of 100 first instars An. gambiae s.s. After emergence of adults from this first batch, the same test media were simply filtered and received a second batch of first instars larvae to make setup 2. Three endpoints were measured in this study: the duration of larval phase, the larval mortality, and the size of adults. Results: The development duration and mortality of larvae decreased significantly at setup 2 with cypermethrin and methyl-parathion. Thus, the duration of larval stage decreased from 10.18 days at setup 1 to 7.84 days at setup 2 for 0.010 礸/l (highest concentration) with cypermethrin and from 10.20 days at setup 1 to 8.27 days at setup 2 for 0.144 礸/l (highest concentration) with methyl-parathion. The larval mortality dropped from 79.32 % at setup 1 to 12.00 % at setup 2 for the highest concentration of cypermethrin and from 76.42 % at setup 1 to 12.50 % at setup 2 for the highest concentration of methyl-parathion. While adults size significantly increased in setup 2. For males, wing抯 length increased from 3.28 mm at setup 1 to 3.49 mm at setup 2 for the highest concentration of cypermethrin, from 3.31 mm at setup 1 to 3.49 mm at setup 2 for the highest concentration of methyl-parathion. In female, wing抯 length increased from 3.52 mm at setup 1 to 3.68 mm at setup 2 for the highest concentration of cypermethrin, from 3.49 mm at setup 1 to 3.68 mm at setup 2 for the highest concentration of methyl-parathion. Conclusion: This work shows that mosquito larvae, especially An. gambiae are able to modify breeding medium to improve its fitness during their development.