Isolation and molecular characterization of free-living amoebas in cape verde

  1. Sousa Ramos, Djeniffer Suleika
Supervised by:
  1. Jacob Lorenzo Morales Director
  2. José Enrique Piñero Barroso Co-director

Defence university: Universidad de La Laguna

Fecha de defensa: 22 September 2023

  1. Basilio Valladares Hernández Chair
  2. Kateřina Trčková Secretary
  3. Ines Araujo Monteiro De Pina Committee member

Type: Thesis


Protists are characterized by the ability to regulate the supply and demand of organic carbon, as well as the balance of oxygen within and between ecosystems. In contrast to these benefits, within this group of protozoa we find free-living amoebae (FLA), which present the dual condition of living freely in the environment or acting as opportunistic parasites, being considered emerging pathogens. FLA are organisms with wide environmental dispersion, isolated in all continents and in the most diverse habitats and present a high resistance to extreme conditions of temperature, pH, chemicals and salinity. At present, 6 groups of FLA have been described as parasites of humans and domestic animals: Acanthamoeba spp, Naegleria fowleri, Balamuthia mandrillaris, Sapinia spp, Vahlkampfia spp and Vermamoeba vermiformis. In addition, free living amoeba have gained importance because they function as carriers of other pathogens of clinical interest. The main infections caused by those amoebas are considered accidental, as in the case of acute Naegleria fowleri meningitis, or opportunistic, such as granulomatous meningitis, keratitis and other epithelial infections caused by Acanthamoeba spp. or Balamuthia mandrillaris. Acanthamoeba is the genus that has attracted most interest in recent years, being one of the most common protozoa present in soil and freshwater. Within the main countries with the occurrence of diseases such as the United States, Belgium, England, Ireland, Australia, New Zealand, West Africa, Venezuela, among others. In the present study, for the first time, the presence of freeliving amoebae in environmental samples from Cape Verde was studied. For this study, water and soil samples were taken and processed for isolation and molecular characterization by PCR and sequencing. The samples were seeded on non-nutrient agar plates (ANN) and the DNA of those positive for FLA growth were sequenced and compared with the sequences available in the NCBI (National Center for Biotechnology Information) GenBank database. During 2019/2020, 67 samples were taken, 31 of different types of water, 10 of WWTS and 26 of soils from different points of the island of Santiago (Cape Verde). Acanthamoeba was found in the highest number of samples, with the T4 genotype predominating. The presence of Vermamoeba vermiformis was demonstrated for the first time in sand by gene amplification for 18S rDNA by polymerase chain reaction, as well as the recently reported free-living amoeba Stenamoeba dejjonckheerei in garden soils. For water samples from the Wastewater Treatment Station in Santa Cruz, the potentially pathogenic amoeba2 Naegleria fowleri was isolated. In this sequence species like Vanella spp have been isolated in this study from soil and water samples, posing a risk to public health by their ability to harbor pathogens. Our results reinforce the objective of the thesis on the epidemiology of FLA, since they were demonstrated in all the environments studied. Their wide distribution, the finding in recreational and drinking waters and in soils reinforce the need to implement control and prevention measures, as well as their consideration by health personnel when making a clinical diagnosis and establishing a specific treatment. This is the first report of potentially pathogenic AVL in Cape Verde