Cholera Outbreak in some communities in North-East Nigeria: An unmatched case-control study

doi:10.21203/rs.3.rs-1646412/v1

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Research Article

Cholera Outbreak in some communities in North-East Nigeria: An unmatched case-control study

https://doi.org/10.21203/rs.3.rs-1646412/v1

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published 07 Mar, 2023

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Background

Cholera, a diarrheal disease caused by the bacterium Vibrio cholerae, transmitted through fecal contamination of water or food remains an ever-present risk in many countries, especially where water supply, sanitation, food safety, and hygiene are inadequate. A cholera outbreak was reported in Bauchi State, North-eastern Nigeria. We investigated the outbreak to determine the extent and assess risk factors associated with the outbreak.

Methods

We conducted a descriptive analysis of suspected cholera cases to determine the fatality rate (CFR), attack rate (AR), and trends/patterns of the outbreak. We also conducted a 1:2 unmatched case-control study to assess risk factors amongst 110 confirmed cases and 220 uninfected individuals (controls). We defined a suspected case as any person > 5 years with acute watery diarrhea with/without vomiting; a confirmed case as any suspected case in which there was laboratory isolation of Vibrio cholerae O1 or O139 from the stool while a control as any uninfected individual with close contact (same household) with a confirmed case. Children under-5 not included in the case definition but samples from this age group were collected where such symptoms occur and line-listed separately. Data were collected with an interviewer-administered questionnaire and analyzed using Epi-info and Microsoft excel for frequencies, proportions, bivariate and multivariate analysis at a 95% confidence interval.

Results

A total of 9725 cases were line-listed with a CFR of 0.3% in the state. Dass LGA had the highest CFR (14.3%) while Bauchi LGA recorded the highest AR of 1,830 cases per 100,000 persons. Factors significantly associated with being a case were non-attendance at social gatherings (aOR = 0.65, 95% CI = 0.5–0.9) and source of water (aOR = 0.65, 95% CI = 0.5–0.8).

Conclusion

Non-attendance at social gatherings and provision of tap water were found to be protective against cholera infection. Public health actions taken included: chlorination of wells and distribution of water guard (1% chlorine solution) bottles to households including public education on cholera prevention messages amongst other actions.

Cholera

Case-control

Risk factors

Outbreak

Nigeria

Cholera, an acute diarrhoeal disease of public health importance is caused by a bacillus Vibrio cholerae, either serogroup O1 or O139 affecting both children and adults [1, 2]. About 20% of those who are infected develop acute, watery diarrhea – 10–20% of these individuals develop severe watery diarrhea with vomiting. If these patients are not promptly and adequately treated, the loss of such large amounts of fluid and salts can lead to severe dehydration and death within hours [1, 3]. The case-fatality rate in untreated cases may reach 30–50% although treatment is straightforward (basically rehydration) and, when applied appropriately, should keep the case-fatality rate below 1% [2, 4]. Cholera is usually transmitted feco-orally through contaminated water or food and remains a risk in many countries. New outbreaks can occur sporadically in any part of the world where water supply, sanitation, food safety, and hygiene are inadequate [1–4]. Refugee settings and over-populated communities that are characterized by poor sanitation, unsafe drinking water, and increased person-to-person transmission account for the greatest risk of this disease. Mild and asymptomatic cholera accounts for 80% of cases with the incubation periods ranging from two hours to five days. Preventing cholera from entering a community is impossible, however, early detection and confirmation followed by an appropriate response can prevent the spread within the community.

Cholera is an acute public health issue with the high potential to cause many deaths, spread quickly and eventually internationally, and seriously affect travel and trade. Therefore, response to the outbreak has to be well-coordinated, timely, and effective [3]. Planning and implementation of preparedness activities that will allow for effective management of future cholera outbreaks should be preceded by good response activities. A strong cholera preparedness plan and program is the best preparation for outbreaks in countries at risk of cholera, whether or not they have yet been affected, or countries in which seasonal recurrence of the disease may be expected [4]. Cholera is endemic in many countries including Nigeria and recent studies have reported that global warming creates a favorable environment for these gram-negative bacteria to thrive [5]. Although reports of the cholera epidemic in Nigeria have not been consistent, the disease is very dynamic and appears to be endemic in Northern Nigeria. The Kano State Ministry of Health, Northern Nigeria, epidemiological data revealed that the frequency and distribution of recurrent cholera epidemics in the state from 1995 to 2001, were 2 630 in 1995/1996, 847 in 1997, and 2, 347 in 1999 [6, 7]. In Jos, North Central Nigeria, the literature showed that all isolated strains were Vibrio cholera 01 Eltor of Inaba serotype [8]. The burden of cholera in Nigeria is more in Northern Nigeria, although, very little is known about the characteristics of the circulating strains. Cholera infection in Nigeria is endemic and outbreaks are usually very common. The lack of potable water in most Northern states in Nigeria has left the people to rely on hand-dug wells and contaminated ponds as their main sources of drinking water. Usually, the source of the contamination is other cholera patients when their untreated diarrhea discharge is allowed to get into water supplies [3, 5]. The outbreak of cholera associated with gastroenteritis and the attendant deaths in some regions in Nigeria brought to the forefront the vulnerability of poor communities and most especially children to the infection [9]. Cholera outbreaks were often attributed to rain which washed sewage into open wells and ponds, where people obtain water for drinking and household needs [5, 7]. Even though the epidemic was recorded in northern Nigeria, epidemiological evidence indicated that the entire country was at risk, with the postulation that the outbreak was due to hyper-virulent strains of the organism [10]. Suspected cholera outbreaks occur annually in Northern Nigeria, particularly during rainy seasons. Previous outbreaks of cholera particularly the 2014 Cholera outbreak were reported in all LGAs of Bauchi State with a total of 16,924 cases and 88 deaths. Bauchi LGA had 14,765 cases (87.3%) of the total cases recorded in the State with 51 fatalities in 2014. Nigeria as one of the cholera foci in the world is characterized by persistent outbreak situations [11]. On 28 February 2019, the Index case of a 12-year-old boy from a Tsangaya (Almajiri) School in the Gwallaga community of Makama B ward of Bauchi LGA was presented to the Abubakar Tafawa- Balewa University Teaching Hospital (ATBUTH) Bauchi on account of sudden onset of watery stool and vomiting. He was successfully managed and discharged after two days of hospitalization. A few hours after the admissions in ATBUTH, another set of two (2) students from Markazi Tsangaya School in the Kobi area of Hardo ward were hospitalized at the Bauchi State Specialist Hospital with only one survival and the first mortality recorded during the outbreak in the State. Sixteen out of the 20 wards in Bauchi LGA and eight other LGAs (Alkaleri, Bogoro, Dass, Darazo, Ganjuwa, Kirfi, Tafawa- Balewa, and Toro) recorded at least 1 case of the disease. An outbreak response team was immediately deployed with the objectives of verifying the diagnosis, describing the extent of the outbreak, identifying associated risk factors, and instituting appropriate control measures by strengthening case management.

Study area

The study was conducted in Bauchi State located in the North-East geopolitical zone of Nigeria with a surface area of 49,259 sq. km. Bauchi State is made up of twenty Local Government Areas (LGAs) with 323 Political Wards. Bauchi city serves as both Bauchi Local Government headquarters and the State Capital respectively. According to the 2006 census, Bauchi state has a population of 4,653,066.

Notification of the Outbreak

On 28 February 2019, few hours after the index case was hospitalized at the ATBU Teaching Hospital, the Epidemiology Unit of the Bauchi State Primary Health Care Development Agency (BASPHCDA) was notified by the Bauchi LGA Disease Surveillance and Notification Officer (DSNO). The State Rapid Response Team (RRT) was mobilized and dispatched to the affected communities/Tsangaya schools including the ATBU Teaching Hospital to investigate the outbreak. The RRT utilized several methods for the outbreak investigations including advocacy visits; active case searches at the health facilities and affected communities; verbal autopsy for retrospective cases in the communities; review of case notes/patient registers at health facilities for retrospective cases; laboratory investigations and questionnaires administration. We conducted an unmatched case-control study to identify outbreak-associated risk factors.

Study population

For the case-control study, we identified 110 cholera cases from the line list of ongoing and recovered patients. Contact tracing was conducted and a semi open-ended questionnaire was administered to them. For every case patient, two controls were identified.

Case definition

Suspected case

We defined a suspected case of cholera as “any person or patient aged 5 years or more with acute watery diarrhea with or without vomiting living in Bauchi State from 28February to 31 August 2019”. To maintain specificity, therefore, children under 5 are not included in the case definition of cholera but samples from this age group are collected where such symptoms occur and are separately line-listed.

Confirmed case

Confirmed case was defined “as any suspected case in which Vibrio cholerae O1 or O139 has been isolated in stool at the laboratory”.

Control definition

We defined control as “any person living in Bauchi State aged 5 years or more who is a friend or family member or neighbor of a case without any history of diarrhea from 28 February to 31 August 2019”.

Identification of cases and recruitment of controls

We selected all current cholera cases and those who had recovered from the line list. Using the case definitions, we conducted an active case search in the affected communities and reviewed health records at health facilities. All cases meeting the case definition were recruited. We extracted data on socio-demographic characteristics (sex, age, residence), date of onset of illness, date of presentation at the clinic, presenting signs and symptoms, history of treatment, and outcomes. Next, we generated hypotheses about possible exposure factors that were common to the cases. Controls were recruited from among family members, friends, and neighbors of the cases. Only persons who reside in the communities at least 10 days before the start of the outbreak and with no symptoms similar to the case definition during the stated period were considered eligible for selection as controls. Where more than two suitable controls were available for a case, only two were selected randomly.

Case Management

A Cholera Treatment Centre at the ATBU Teaching Hospital Bauchi was set up to attend to all cholera cases in the state. This center was supported and managed by partners- Medecins San Frontiers (MSF). Referral and suspected patients in and around Bauchi LGA were brought in for management. The case identification procedures of all the health facilities in the affected wards were also reviewed.

Questionnaire Survey

We used interviewer-administered questionnaires to collect the following information from cases and controls; socio-demographic characteristics, clinical information from cases, and possible exposure factors. The determination of risk factors for cholera infections involved the administration of questionnaires to assess the association between general hygiene vis-à-vis cholera infections amongst individuals in the communities where the outbreak occurred. Consent was sought before administering the questionnaire to cases and controls. Data on behavioral habits collected included house characteristics, source of water, fruits and vegetables, management of waste, hygienic practices such as cleaning and disinfection procedures, types of toilet facility, eating habits, number of individuals in a household, and date of onset of the disease. The questionnaire was designed and pretested on 20 individuals in and around Bauchi LGA and the questions were adjusted as necessary. However, data from the pretesting was not included in the final analysis.

Laboratory investigations

We used universal sterile bottles to collect stool samples for laboratory confirmation within 24 to 48 hours of the onset of illness. Each appropriately labeled specimen was immediately transported to the nearest microbiology laboratory within one hour of collection where they were quickly processed for culture, gram staining, and antibiotic susceptibility testing. However, treatment of dehydrated patients was initiated immediately before the laboratory confirmation.

Environmental assessment

Based on our observations and findings in the community, we assessed the following possible risk factors: Open defecation sites in about 66 communities within the metropolis; Poor environmental hygiene/sanitation as indiscriminate refuse dumpsites were seen all over the metropolis; limited access to safe water from the public water supply network; personal hygiene practices; broken pipes and leakages especially along service lines; wells as the major source of drinking water with most of them poorly protected; siting of latrines close to wells and exposed sewage as well as blocked drainages. We also inspected the homes of the cases for possible exposure factors.

Data analyses

The data were analyzed using univariate analysis. Categorical variables were summarized as frequencies and proportions, while quantitative variables (such as age), were expressed as mean and standard deviation. We calculated case fatality rates and developed a weekly epidemic curve to show the distribution of the cases by date (weeks) of onset of illness and date (weeks) of dead. A bivariate analysis was conducted to identify risk factors associated with a cholera infection. Any variable significant at p < 0.05 was included in the multivariate logistic regression model in a forward and backward stepwise fashion. Variables were included or excluded from the model based on the adjusted Wald test statistics, and only variables with p < 0.05 were retained. For variables that have multiple levels, one variable must be significantly different from the baseline (reference) for the variable to be retained. Possible confounders were controlled for by including these variables in the logistic regression model.

Ethical considerations

We obtained written informed consent from study participants and caregivers of children before questionnaire administration as most of our respondents were uneducated. We assured the respondents of the confidentiality of information obtained. Permission was also obtained from the management of ATBU Teaching Hospital Bauchi before record review.

Descriptive epidemiology of the Cholera Outbreak

The epidemiologic investigation identified 9725 cases in ten LGA of Bauchi state and 6 cases from neighboring Plateau State. A total of 28 fatalities was recorded with a total case fatality rate (CFR) of 0.29%. Dass LGA has the highest CFR of 14.29. Bauchi LGA, with a total population of 493, 810 based on the 2006 population censors had the highest attack rate of 18,261 per 1,000,000 while Katagum and Alkaleri had the lowest attack rate of 4 per 1,000,000 (Table 1). Consequently, the Bauchi LGA had the highest percentage of all the cases recorded during the outbreak (92.7%) as well as the most hit in terms of the number of deaths.

Table 1

Case fatality rates and attack rates associated with 2019 Bauchi State Cholera outbreak
LGA	Population (based on 2016 censors)	Number of cases	Death	Proportion of cases by LGA	Case fatality rate (%)	LGA attack rate/1,000,000
Alkaleri	329, 424	1	0	0.01%	0.00	4
Bauchi	493, 810	9017	24	92.70%	0.27	18,261
Bogoro	84,215	10	0	0.10%	0.00	119
Darazo	251,597	2	0	0.02%	0.00	8
Dass	89,943	7	1	0.07%	14.29	78
Gajuwa	280,468	242	1	2.49%	0.41	863
Kirfi	147,618	1	0	0.01%	0.00	7
Tafawa Balewa	219,988	397	2	4.08%	0.5	1,805
Toro	350, 404	41	0	0.42%	0.00	118
Katagum	295,970	1	0	0.01%	0.00	4
Plateau State		6	0	0.06%	0.00
Total		9725	28	100.00%	0.29

Case Control Study

The study population comprised 330 participants (110 cases and 220 controls) with a response rate of 100%. Overall, the mean ages of the participants were 24.8 ± 12.9 years. Females were more 51.5% (n = 170); majority were students 44.9% (n = 148); had secondary education 42.1% (n = 139); and were not married 63.3% (n = 209). The mean ages of cases and controls were 21.8 ± 12.5 years and 26.2 ± 12.9 years respectively. Cholera cases were slightly higher among females (38.8%) as compared to males. However, infection in children less than 5 years was low (28.4%) when compared to individuals above 5 years (Table 2).

Table 2

Socio-demographic characteristics of cases and controls in Bauchi, 2019
Variables	Cases n (%)	Controls n (%)	Total n (%)
Total	110 (33.3)	220 (66.7)	330 (100)
Age (years)
0–5	10 (9.1)	2 (0.9)	12
6–20	48 (43.6)	86 (39.1)	134
21 and above	52 (47.3)	132 (60.0)	184
Gender
Female	66 (38.8)	104 (61.2)	170 (51.5)
Male	44 (27.5)	116 (72.5)	160 (48.5)
Marital Status
Single	79 (37.8)	130 (62.2)	209 (63.3)
Married	31 (25.6)	90 (74.4)	121 (36.7)
Education
None	28 (40.0)	42 (60.0)	70 (21.2)
Primary	8 (21.1)	30 (78.9)	38 (11.5)
Secondary	51 (36.7)	88 (63.3)	139 (42.1)
Tertiary	23 (27.7)	60 (72.3)	83 (25.2)
Occupation
None	29 (31.5)	63 (68.5)	92 (27.9)
Student	63 (42.6)	85 (57.4)	148 (44.9)
Civil Servant	18 (20.0)	72 (80.0)	90 (27.2)

Figure 1: Epidemic curve of cholera cases by week of onset in Bauchi State from 11th February 2019 to 9th September 2019

The epidemic curve for the cholera outbreak is shown in Fig. 1. The index case was reported on 28 February 2018 (week 9 of 2018). Thereafter there was a steady rise in the number of cases which eventually peaked by week 19. This coincided to the peak of heat period characterized by scarcity of portable drinking water. The peak of the outbreak was followed by a sharp decline at the beginning of second week of May, which coincided with the commencement of response activities by the Rapid Response Team and the setting up of the cholera treatment center in the state. This was followed by abrupt fall in fatality among the cases. The outbreak ended at the end of 35th week (14 days after the last case was admitted).

Figure 2: Symptoms of Cholera cases in Bauchi, September 2019

Watery diarrhoea was the symptom most frequently reported by the cases (98.2%, n = 108); followed by vomiting (82.7%, n = 91); abdominal cramps (64.5%, n = 71) while fever (60.0%, n = 66) was the least reported. All the symptoms were reported by 39.1% (n = 43) of the cases (Fig. 2).

Out of 24 samples tested, 20 were confirmed positive for Vibrio cholerae using both rapid test kit and culture however the nine water samples obtained from wells and the public water supply network in the most affected communities were negative. Compared to the controls (58.2%), cases (94.5%) were more likely to dispose refuse in the backyard or bush or a combination of both than by burning (OR = 2.44, 95% CI = 0.98–6.09) hence contaminating the environment as this can easily be washed off when it rains into water bodies.

Factors associated with the cholera outbreak in Bauchi were: gender (OR = 1.67, 95% CI = 1.05–2.66); occupation (OR = 2.96, 95% CI = 1.61–5.46); travel history (OR = 1.71, 95% CI = 1.03–2.81); contact with diarrhoea case (OR = 1.68, CI = 1.03–3.36); attend social gathering (OR = 0.10, CI = 0.05–0.23) see Table 3.

Table 3

Factors associated with Cholera outbreak at bivariate analysis, Bauchi, 2019
Variables	Cases	Control	OR	95% CI	P-value
Gender Female Male	66 44	104 116	1.67	1.05–2.66	0.04
Occupation None Student Civil servant/ business	29 63 18	63 85 72	1.84 2.96 Ref	0.93–3.63 1.61–5.46 Ref	0.11 0.0006
Travelled 10 days prior to the disease? Yes No	38 72	52 168	1.71	1.03–2.81	0.05
Contact with diarrhea patient? Don’t know Yes No	28 20 62	32 56 132	1.86 0.76 Ref	1.03–3.36 0.42–1.37 Ref	0.05 0.47
Attend social gathering? Don’t know Yes No	8 46 56	170 55 124	0.10 1.85 Ref	0.05–0.23 1.12–3.06 Ref	0.000 0.02
Source of drinking water Water vendor/pure water Well Combination of any of the above Borehole/tap water	27 37 32 14	56 33 87 44	1.52 3.52 1.16 Ref	0.71–3.23 1.64–7.56 0.56–2.39 Ref	0.37 0.002 0.83 Ref
Where do you buy fruits/vegetables? Market Road side Don’t shop/Don’t remember	85 12 13	152 12 56	2.41 4.31 Ref	1.25–4.66 1.58–11.74 Ref	0.01 0.007 Ref
Consumption of food/water prior to disease Food sellers Other household/Neighbors Both None	14 25 27 44	78 58 19 65	0.27 0.64 2.10 Ref	0.13–0.53 0.35–1.17 1.04–4.23 Ref	0.000 0.19 0.05 Ref
Refuse disposal Dumping in the backyard Dumping in the bush Combination of any of the above Burning	49 12 43 6	105 44 43 27	2.10 1.23 4.50 Ref	0.81–5.42 0.41–3.65 1.69–11.99	0.18 0.92 0.003

In the logistic regression model used, the following factors which were significant at bivariate analysis (p = 0.05) were subsequently added in the model, including contact with diarrheic patient, not attending social gathering, consuming food/water from food sellers, travel history, gender, waste disposal methods, occupation, source of drinking water and source of vegetables. After controlling for gender and using a stepwise elimination approach, only two factors remained statistically significant in the logistic regression model. In the final logistic regression model, not attending social gathering or event (adjusted OR [aOR] = 0.65, 95% CI = 0.46–0.94) and access to tap water as drinking water source (aOR = 0.65, 95%CI = 0.52–0.81) remained protective factors against being infected with Vibrio cholera during the outbreak. Based on logistic regression analysis, we found that individuals who did not attend a social gathering or event (p = 0.02) and had access to tap water (p = 0.01) were protective from the cholera outbreak (Table 4).

Table 4

Risk factors of Cholera Outbreak in Bauchi, September 2019
Variables	Adjusted Odds Ratio	95% C.I.	P-Value
Contact with diarrheic patient	1.01	0.70–1.46	0.94
Not attending social gathering or event	0.65	0.46–0.94	0.02
Food/water from food sellers	0.98	0.75–1.28	0.90
History of travel anywhere in the 10 day (2/1)	1.65	0.94–2.91	0.08
Gender (2/1)	1.48	0.90–2.44	0.13
Waste disposal	1.23	0.95–1.43	0.12
Occupation	0.84	0.61–1.18	0.32
Type of drinking water	0.65	0.52–0.81	0.01
Where do you shop for fruits and vegetables	1.09	0.84–1.43	0.51

The cholera outbreak in Bauchi state was caused by Vibrio cholera. Cholera is primarily a disease in underdeveloped and developing counties especially when there is a disruption in public sanitation services or normal balance of nature hence creating health problems as food and water supplies can become contaminated in such scenarios [12].

The index case was a young ‘Almajiri’ boy from an Islamic school. Most Islamic schools do not have toilet facilities for the pupils hence open defecation is the usual practice [13]. They lack access to potable water and mostly rely on open well water as their source of drinking water. The lack of these basic amenities coupled with exposure to poor sanitary and environmental conditions predisposes the group of children to the infection through the feco-oral route [3, 13].

In Bauchi LGA being the epicenter of the outbreak, the case fatality rate of 0.27% was very low when compared with reports of similar outbreaks [1, 9]. This was probably due to the presence of a cholera treatment center as well as the prompt response of the RRT in curtailing and controlling the infection from spreading to other parts of the state. Health education messages were also disseminated in affected communities via the mass media during the outbreak which led to better health-seeking behavior at treatment centers. Healthcare workers received refresher training on how to promptly identify cases; disinfect public and private toilets; chlorinate public and private wells and vaccination. Vaccination against cholera in Nigeria is usually not common [3]. Oral cholera vaccines were provided as a part of the outbreak response. For most individuals, this was the first time they had received the cholera vaccine with the support of NGOs. This is in agreement with reports of other studies where oral cholera vaccines were deployed during a cholera outbreak [14].

The outbreak affected different age groups in the affected areas, however, those who were 21 years and older had the highest proportion of cases. This is not consistent with findings of similar outbreaks in Nigeria where the most affected age group was 5–9 years [1, 3].

Gender was found to be associated with the outbreak as the odds of having cholera infection was 1.67 higher in females than in males and consistent with reports of other studies [9]. This was not surprising as women often make use of unhygienic water for cleaning, washing, cooking, or drinking when compared to men. The odds of infection amongst those that traveled 10 days prior to the infection was 1.71 higher than those that did not travel. This is similar to the report by Okeke et al. (2001) where population movement was shown to enhance the spread of the infectious agent to others and to different locations [15].

Similarly, the odds of infection amongst those that attended a gathering within the time of the outbreak were 1.85 higher than those that did not. Common source epidemics as suggested by the epidemic curve usually occur at gatherings such as a party or festivities. The fact that infection started with the ‘Almajiris’ who are known to beg for arms and ‘’left-over’’ food/drinks [16]. It is not surprising that the ‘Almajiris’ had a common source of epidemic infection from the consumption of contaminated ‘left-over’ food. Not attending a social event was found to be a protective factor for acquiring cholera infection in the present study. This protective factor appears to be less informative, and not much can be deduced about these until further information is available as to how they influence cholera protection.

In addition, tap water as a source of drinking water was also found to be a protective factor as the odds of infection in those who drank well water was 3.52 times higher than in those who drank borehole/tap water. This is consistent with findings of a similar study in Nigeria where drinking tap water was protective against the cholera outbreak, and another study in Papua New Guinea that reported piped water was protective against cholera [17, 18].

Consumption of food and water prior to the infection from food sellers was 0.27 times higher than those that did not consume food during the food sellers. However, those who consumed food prior to the infection from both the food sellers and from other households/neighbors were found to be 2.10 times more likely to be infected.

Those who dispose of their refuse in their backyard or in the bush were found to be 4.50 times more likely to be infected with cholera when compared to those who burn their refuse. It is not uncommon to see refuse thrown at the backyard or in bushes being washed back by rainwater into rivers, surface wells, etc thereby contaminating the water sources at various homes.

The prevention and control strategies practiced in Nigeria are multi-sectoral. Registration of cases, case management, and public health measures targeting personal hygiene and water treatment, as well as emergency responses as some of the Epidemic Preparedness and Response (EPR), measures put in place by both governmental and non-government agencies, have contributed to the reduction in case of fatality rates over the years and should be sustained [5]. However, to wholly curtail the infection, there is a need to explore more viable approaches. The endemicity of cholera in Nigeria provides a good avenue to use the surveillance system as an early alert for cholera outbreaks that will lead to a coordinated response. More importantly, it is necessary to introduce intervention measures that address the root problems of poor sanitation and unsafe water supplies in order to prevent future cholera epidemics [5, 19]. In this regard, perhaps, prevention of the disease is the best way to counter subsequent outbreaks. Measures such as boiling the water (for drinking, washing, and cooking purposes); sewages and drainage systems clearing; proper disposal of infected materials (such as waste products, clothing, and beddings); treatment of infected facilities; treatment of infected fecal waste water produced by cholera victims and sterilization of utensils either by boiling or by using chlorine bleach will greatly reduce the incidence of cholera outbreaks. Studies have also indicated that the use of soap and handwashing promotion can achieve a 26 to 62% decrease in the incidence of diarrhea in developing countries [20–22]. Understanding the seasonality and location of outbreaks has been instrumental in providing appropriate guidance for cholera control activities in vulnerable areas [5, 19]. Health promotion activities including public enlightenment campaigns on cholera are important in ensuring that cholera outbreaks are controlled [5]. Health systems need to be strengthened with the provision of adequate manpower, equipment, drugs, and consumables [23]. To prevent future cholera outbreaks, there should be an improvement in surveillance systems, communication, transport, and mechanisms for quick intervention [24].

The cholera outbreak in Bauchi State was investigated and established that it was a common source of cholera epidemic due to the consumption of contaminated left-over food. Poor waste disposal and inadequate supply of clean drinking water within the Bauchi metropolis and its environs contributed to the spread of the outbreak. Drinking tap water and not attending social gatherings were identified as protective factors. Based on our findings, we organized health talks on proper hand hygiene and chlorinated existing wells in the affected communities. We recommended to the State government to improve the public water supply network to the inhabitants of the Bauchi metropolis and its environs, construct boreholes or protected wells as well as the establishment of good waste disposal systems. In addition, we recommended that the state government provides Oral Cholera Vaccines as well as recruit more Environmental Health workers (Dubagari) to enforce hygiene and sanitation laws.

ATBUTH: Abubakar Tafawa- Balewa University Teaching Hospital

AOR: Adjusted Odds Ratio

AR: Attack rate;

BASPHCDA: Bauchi State Primary Health Care Development Agency

CFR: Case fatality rate

Confidence interval

DSNO: Disease Surveillance and Notification Officer

LGA: Local Government Area

OR: Odds Ratio

RRT: Rapid Response Team.

Ethics approval and consent to participate

The research methods stated in this manuscript were carried out according to relevant guidelines and regulations. The Research Ethics Committee of Abubakar Tafawa Balewa University (ATBU) waived ethical approval because of the exigencies of the outbreak response. Permission was obtained from the Public Health Department of all the affected Local Government Areas (LGAs) for theduration of the outbreak response. All the respondents were above 18 years and provided written informed consent before questionnaire administration and sample collection. Confidentiality of information obtained was assured as respondents were provided unique identifiers.

Consent for publication

Not applicable

Availability of data and materials

The datasets used and analyzed during the current study are available from the corresponding author on reasonable request. All data generated during this study are also included in this published article [and its supplementary information files].

Competing interests

The authors declare that they have no competing interests

Funding

The Bauchi cholera outbreak investigation was funded jointly by the Bauchi State government, the Nigeria Center for Disease Control, and Africa Field Epidemiology Network.

Authors’ contributions

IOF and MA were the principal investigators, conceptualized the study, designed data collection tools, collected data, analysed and interpreted the data, and wrote the first draft of the manuscript. BG, IA, and BU made substantial contributions to conception and design. JK, EC, NW, MB, PN, and MKA provided supervision. MKA wrote the second draft. JK, EC, NW, MB, PN, and MKA revised the article critically for important intellectual content. All authors read and approved the final manuscript.

Acknowledgments

The authors would like to appreciate the management of Abubakar Tafawa- Balewa University Teaching Hospital, the Epidemiology Unit of the Bauchi State Primary Health Care Development Agency, Bauchi LGA Disease Surveillance and Notification Officer (DSNO), and the State Rapid Response Team for their support towards the success of the investigation.

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No competing interests reported.

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Cholera Outbreak in some communities in North-East Nigeria: An unmatched case-control study

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Background

Materials And Methods

Results

Descriptive epidemiology of the Cholera Outbreak

Case Control Study

Discussion

Conclusion

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