**5. Conclusions**

*Pathogenic Bacteria*

environment.

*4.4.8* Bacillus

*4.4.9* Salmonella

sachet water by previous investigators.

profuse diarrhea, and molecular epidemiological surveillance has revealed clonal diversity among toxigenic *V. cholerae* strains with continuous emergence of new epidemic clones. It has not been established if the strains found in boreholes and sachet water are the *V. cholerae* O1 or O139 strains that cause cholera [100]. There is a possibility that they could be non-O1 or non-O139 strains that are common in the

In 2017, the WHO launched a global strategy on cholera control with a target to reduce cholera deaths worldwide by 90% [101]. The strategy is to use safe oral cholera vaccines in conjunction with improvements in water and sanitation to control cholera outbreaks and for prevention in areas known to be high risk for cholera. Nigeria can be classified as a high-risk area, and the occurrence of *Vibrio* species in borehole or sachet water suggests that they could transmit cholera. Outbreaks occur regularly in Nigeria, and it is always difficult to bring it under control. An outbreak in 2018 was characterized by four epidemiological waves and led to 836 deaths out of 43,996 cases [102], whereas that of 2010 killed a total of 1716 out of 41, 787 cases [103]. In both cases, the case fatality rate was over 1% recommended by WHO.

*Bacillus cereus* is a food safety concern among several species of *Bacillus*. It is naturally widely distributed in nature, and it is known as a Gram-positive rod bacterium that is responsible for food poisoning [104]. It can proliferate because of unhygienic practices [105] and can attach to drinking water infrastructure [106]. This suggests that the ubiquity of the organism, poor hygiene, and attachment to equipment may be why *Bacillus* has been repeatedly isolated from boreholes and

*Bacillus* growth is sometimes considered an insignificant contaminant. Some strains like *B. subtilis* is used for probiotics [107], whereas a strain like *B. cereus* which secrets toxins like hemolysins, phospholipases, an emesis-inducing toxin, and proteases [108] is not used due to obvious reasons. Toxin production in *B. cereus* requires the transcription factor *PlcR*, which controls expression of virulence factors [109]. Virulence-associated gene profiles have been used to evaluate the genetic backgrounds and relationships of food poisoning cases among other isolates from the environment, and it was concluded that both molecular and epidemiological

The species *Salmonella typhi* and *Salmonella paratyphi* cause typhoid fever and remain a major public health concern in Asia and Africa [111] due to antimicrobial resistance. For developed countries, it is believed that some non-typhoidal strains are zoonotic in origin and acquire their resistance in the food animal host before onward transmission to humans through the food chain [112]. It has been reported that the overall global burden of *Salmonella* infections is high and this may be the reason why in 2017, the WHO listed fluoroquinolone-resistant *Salmonella* spp. as

The bacterium can survive in aquatic environments by a number of mechanisms, including entry into the viable but non-culturable state or residence within free-living protozoa [114]. Survival in water may have contributed to the isolation from borehole and sachet water in studies by others. It is not certain if the isolates encountered in this study cause typhoid fever or are the non-typhoid causing strains. Hence, additional studies are required to establish the prevalent type of *Salmonella* in water-producing facilities in Nigeria. A recent report found

surveillance studies could be used effectively to estimate virulence [110].

priority pathogens for which new antibiotics were urgently needed [113].

**224**

The overall bacteria quality of the borehole and sachet water in the community studied needs improvement. An improvement can be achieved by focusing on areas with coliform contamination. Boreholes should be sited where pollutants will not easily contaminate them. Regular water testing should be carried out to ensure the attainment of WHO guidelines always. Where deviations are found, corrective actions should be undertaken. The literature on bacteria from boreholes and sachet water in Nigeria shows that not much molecular characterization has been carried out; hence an opportunity exists for more investigations. Regulatory oversight for sachet water production and the use of boreholes by large community populations requires improvement. It is recommended that universities should carry out periodic surveillance of boreholes and sachet water sold near them to support the SDG targets of the WHO.
