ABSTRACT
Essential oil was extracted from Ocimum suave Willd leaves by water distillation and tested for repellency effectiveness against Anopheles gambiae adult mosquitoes. The percentage yield of the essential oil was 0.2%. Six concentrations of O. suave essential oil were applied on human skin of four volunteers, and the repellency effectiveness which was analyzed by PoloPlus (LeOra software version 1.0, 2002-2014), revealed promising RC50, RC75, RC90 and RC99 with their confidence limits as 0.1161 mg/cm2 (0.02067 - 0.1767 mg/cm2), 0.2823 mg/cm2 (0.22328 - 0.3654 mg/cm2), 0.4319 mg/cm2 (0.35226 - 0.58862 mg/cm2) and 0.98934 mg/cm2 (0.54731 - 0.99972 mg/cm2), respectively. O. suave essential oil exhibited high Anopheles mosquitos’ repellency effectiveness which merits further scientific attention for the development of natural repellents for the control of malaria and other mosquito borne diseases. These findings provides a scientific evidence and base for formulation for further mosquito repellency semi-field and field trials for the development of cheaper and affordable new mosquito repellent product(s) to meet human healthcare needs in the prevention and control of malaria and other mosquito transmitted infections.
ABSTRACT
Background: There is currently an increased demand and consumption of bottled water in Tanzania especially among the middle and high income earners as it is generally perceived to be pure, clean and of good quality. This has led to the sale of different brands of bottled water on the Tanzanian market. Due to increased demand and consumption of bottled water in Tanzania, there has been a growing concern about the microbiological quality of this product. The objective of this study was to assess the physico-chemical quality parameters and microbial contamination level with thermotolerant fecal coliform bacteria commercial bottled water Dar es Salaam city in Tanzania. Materials and Methods: This cross sectional study was done in randomly selected ten different commercial brand of bottled water available in commercial market of Dar es Salaam city in Tanzania. Tap water from Dar es Salaam Water Supply Company (DAWASCO) was also sampled for comparison. Fecal coliform were enumerated by the membrane filtration and commercial field testing DelAgua®kit. The physicochemical examination of the water samples was done to determine pH, turbidity and Total Dissolved Solids (TDS) of the water samples using a Hach spectrophotometer (Hach Company, Loveland, Colorado, USA). Results and Discussion: All samples of bottled water (100%) analyzed did not show the presence of thermotolerant faecal coliform bacteria and thus meet the World Health Organization (WHO) acceptable value of zero cfu/ml. All the surveyed brands of bottled water were safe for drinking as they were devoid of any thermotolerant fecal coliforms bacteria. Tap water from DAWASCO revealed thermotolerant fecal coliforms contamination with mean CFU counts of 4.0/100ml. Coliform organisms found in tap water in this study were above the recommended levels by regulatory agencies such as Tanzania Bureau Standard (TBS), International Bottled Water Association (IBWA), Food and Drug Administration (FDA), United States Environmental Protection Agency for (USEPA), World Health Organization (WHO) and the European Community (EC). The overall mean results of the physicochemical parameters of bottled water brands and tap water studied were within the recommended limits by TBS and WHO. Conclusions: The absence of thermotolerant fecal coliform bacteria in the bottled water is indicative of safety for public consumption. Tap water from DAWASCO is unfit for human consumption and it needs to be treated to render it safe for human drinking. Physicochemical parameters revealed that the pH, TDS and turbidity were within the required levels by TBS and WHO. This indicates that, the manufacturers of bottled water brands and DAWASCO are conforming to the TBS and WHO standards on physicochemical requirements for drinking water.
ABSTRACT
Background: The Indian house crow, Corvus splendens (Vieillot) was introduced in Zanzibar, Tanzania by the British and immigrants from India in 1897 to help clean the town. The crow is responsible for polluting the environment, water sources and human surroundings by their droppings and the rubbish they carry. This behavior has led to concern that, the crows may be responsible for the spread of certain pathogens including Salmonella and their persistence in the environment.Given the zoonotic potential of Salmonella, the main aim of this study was to investigate the occurrence of antimicrobial resistant Salmonella infections in Indian house crows and to determine if the isolates were similar to those associated with disease in livestock or humans. Methods: Indian house crows were lured with meat and blood baits to land into the crow live-trap set at the Mabibo compound of the National Institute for Medical Research (NIMR) in Dar es Salaam city in Tanzania. A total of 100 house crows were captured, humanely sacrificed, and their small and large intestines were obtained by using aseptic techniques for microbiological investigations. Culture technique was employed to detect the presence of Salmonella in intestinal contents; and preliminary identification of the isolates was based on colonial characteristics on selective media and microscopic examination of smears following Gram staining. Confirmation of Salmonella species was done by biochemical tests. Antimicrobial susceptibility testing was done by using the disc diffusion method on Mueller Hinton agar. Results and Discussion: Eight isolates were identified by standard microbiological techniques as Salmonella spp. (6 suggestive of Salmonella gallinarum and 2 suggestive of S. Typhi). All isolates were found to be susceptible to ciprofloxacin but resistant to amoxicillin. Lower levels of susceptibility were noted for chloramphenicol and ceftriaxone. Our results demonstrate the presence of antimicrobial resistant Salmonella spp. in the Indian house crows’ population and provide an indication of potential public and poultry health risks associated with these birds in the coastal area. Conclusion: The occurrence of antibiotic resistant S. Typhi and S. gallinarum among Indian house crows has both veterinary and public health consequences as they may be transmitted to poultry and humans. This therefore provides further rationale for the public action on eradicating the house crows.
ABSTRACT
Aim: To assess inhibitory effect of extracts, alone and in combination, from Carissa spinarum Linn (C. spinarum L.) and Carica papaya Linn (C. papaya L.) on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The combined extracts used were C. papaya L leaves petroleum ether extract/C. spinarum L root methanolic extract (CPLP/CSRM), C. spinarum L leaves petroleum ether extract/C. papaya L seed ethanolic extract (CSLP/CPSE), C. spinarum L root ethanolic extract/C. papaya L leaves ethanolic extract (CSRE/CPLE), C. papaya L root ethanolic extract/C. spinarum L bark ethanolic extract (CPRE/CSBE) and C. papaya L leaves methanolic extract/C. spinarum L leaves methanolic extract (CPLM/CSLM). Study Design: In vitro antibacterial assay. Place and Duration of Study: Samples were collected from Samunge village at Loliondo in Ngorongoro district located in northern Tanzania. Antimicrobial bioassay was carried out at the Department of Molecular Biology and Biotechnology, University of Dar-es- Salaam, between March 2013 and June 2013. Methodology: The broth micro dilution method was used to determine minimum inhibition concentration (MIC). Fractional inhibitory concentrations were calculated from MICs of individual and combined extracts to determine interactions. Results: Plant extracts demonstrated MICs ranging from 312 to 5000 μg/ml. The combination of plant extracts against S. aureus resulted into antibacterial activity of CPSE, CPRE, CPLM, CSLM and CPLP extracts to increase by 4-, 2-, 4-, 4-, and 2-fold, respectively. Activity of CSLP, CPLM and CSLM increased by 2-fold against E. coli. Synergy was demonstrated by CPLM/CSLM against S. aureus. Some combinations were additive including CPRE/CSBE, CPLP/CSRM and CSLP/CPSE against S. aureus and CSLP/CPSE, CPRE/CSBE, CPLM/CSLM against E. coli. Nevertheless, antagonism was demonstrated by CSRE/CPLE, CPLP/CSRM against E. coli and CSLP/CPSE and CSRE/CPLE against S. aureus. Conclusion: This study revealed the importance of using plant-based antibacterial agents in combined therapy to increase efficacy. Extracts of C. spinarum L and C. papaya L could be a source of antibacterial agents when utilized in combination therapy for patients with severe E. coli and staphylococcal infections. These predictors, however, need to be validated to improve their quality.