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FELTP Residents investigate suspected Anthrax outbreak in Narok County, Kenya


A team of residents including; Mathew M. Mutiiria - Team Lead & Resident, Kenya-FELTP, Dr. Jack Omollo - Field Supervisor, Kenya-FELTP, Dr. Gerald Munai; Resident, Kenya-FELTP, Dr. Philip Ngere- EOC/DSRU, Fred Otieno – WSU and Dr. Grace Njeri- ZDU investigated a suspected Anthrax outbreak in Narok Country, Kenya.  


Anthrax is a zoonotic disease of public health significance associated with human and livestock morbidity and mortality as well as decreased trade in livestock and derived products. These outbreaks in animals mostly occur during prolonged periods of hot, dry weather following heavy rain and flooding. Human infection is correlated with incidence of disease in domestic animals (Doganay et al., 2015). Majority of human cases occur in agricultural environment as a result of individuals coming into contact with dead or dying animal. In many impoverished regions, human behaviour and social construct force livestock owners into slaughtering animals at first sign of infection to salvage meat, skin and hides.


Due to its public health and economic impacts anthrax is categorized as notifiable disease. Therefore it is required that all suspected livestock and human cases within Kenya  be reported to the government, which upon confirmation must formally inform the World Organization for Animal Health and the World Health Organization (WHO) respectively.  

In Kenya recent anthrax outbreaks have been reported in many counties, these includes Tharaka Nithi, Meru, Muranga and Kiambu among other counties.   

Narok County reported deaths from suspected anthrax where two people died on 13 November 2018. The reports were received through integrated disease surveillance and response (IDSR). Narok county disease surveillance coordinator, reported that about seventeen (17) people presented with lesions on the skin, abdominal discomfort/pain, cough and difficulty in breathing. Two of the people who died were relatives (mother and son). It was reported that the mother was the one who slaughtered the goat.    


Following sudden death of a goat in Nkoirero village, unknown number of people were suspected to have consumed the carcases, “The actual number of people who consumed the meat is not known but it’s estimated that over 100 people ate the meat as they were attending a function in the neighbourhood. No samples were collected for laboratory confirmation. However based on signs and symptoms (skin lesions, abdominal discomfort/pain, cough and difficulty in breathing) that patients presented with, anthrax was suspected. Establishing factors associated with exposure and spread of the outbreak will inform future prevention and control strategies.

The investigation was carried out in Oloolaimutia village, Siana ward as well as the health facilities that had reported cases of anthrax. Narok west Subcounty is one of the six sub counties of Narok County.  

The study was carried out from 5 – 9 December 2018. Case definition for record review will be any record of a patient with fever and any of the following skin lesions, cough, difficulty in breathing, abdominal discomfort and headache with a history of  handling or consuming meat from a dead animal in Ololopili village from 1st November 2018 to 30th November. A suspected case was defined as an acute illness with a painless skin lesion developing over 2 to 6 days with or without edema, fever, malaise and lymphadenopathy in a person of any age residing in Ololopili village, since 1st November, 2018 following consumption or handling of meat from a goat carcass.

The team defined contacts  as persons who have a history of contact with suspected anthrax animal since November 1 2018. Type of contact will include the following: slaughtering, skinning, cutting in small pieces (butchering), cooking, consumption, burying, sleeping on the skin, being in close proximity where the animal is being killed or any other contact with suspected anthrax animal or its products.  

Community KPP study 

Sample size determination;

Sampling unit was  the household, ccalculated sample size using Cochran formula (Israel, 2013) with 88% proportion for awareness (Sitali et al., 2017).

n = Z2* P (1-P)/d2 



Z-value = 1.96 (Z-score for the 95% Confidence Interval) 


p= Prevalence (88%) Proportion of people aware of anthrax  


d = precision (0.05 at 95% confidence interval) 


Therefore, n = {1.962 * 0.88(1 – 0.12)/0.052} = 163 


To cater for design effect; 163*2 = 326 Households  


Sampling method

Multistage sampling approach was   used in selecting the households (HH) that we recruited in the study. The sub county consists of (four) 4 wards consisting of 80 villages. The ward in the epicenter was purposively considered for the survey. Due to the vastness of the ward and the advice from the office of the county government department of health, we resolved that we do the study that we got additional. We obtained the list of all villages from the local public health office. The village in the epicenter was purposively included while we will randomly selected six (6) (14) villages from the ward. 


To determine the households to be visited in each village, a central reference point (e.g. landmark, church, school, chief’s house, shopping center) was identified. From the central reference point we spinned a bottle to determine the direction where the head is facing. They walked in that direction and located the first household to interview. Subsequent households to be interviewed were selected from the first household by skipping 2 households. The process was repeated until half of the number of households were interviewed in that village. The team then returned to the central reference point and move in the opposite direction and repeat process until the total number of households to be interviewed in the village was achieved. In every selected household, the household head or in his/her absence the senior-most resident of the household who must be over 18 years were selected for interview. Both livestock-owning and non-livestock-owning households were considered in the study. Those household that did not have anybody present during the visit or does not have a person who meet the inclusion criteria for interview or declines to take part in the study, the next immediate household was visited.  


Data Collection

Data was abstracted using a standard tool and uploaded into Epi info version 7.2.2. For human cases, the information to be collected includes age, sex, and residence, date of exposure, exposure information, treatment information, and date of onset of symptoms, treatment and outcome.

 Community KPP survey

To assess knowledge, perception and practices of the Community in regard to anthrax we used structured questionnaire mostly with closed ended questions. The information that we collected using the questionnaire include socio-demographic (age, sex, occupation), information on knowledge (awareness of anthrax, etiology/ causes, transmission, clinical symptoms, prevention and control); attitude (opinion about anthrax disease, government responses in disease outbreaks and treatment of sick animals) and practices (meat consumption and other exposure practices, treatment seeking behaviors and treatment of sick animals)

A questionnaire was written in English and we involved translators to the team communicate. Before collecting data in each village, three field assistants were oriented to the questionnaire by the principal team investigators in order to ensure consistency in data collection and help in customise the questions to local dialects. Data was collected through face to face interviews involving structured questionnaires, focused group discussion (FGD) and key informant interviews (KII)

Magnitude of the anthrax outbreak

A total of 35 persons were traced. Out of which 57.1% (20/35) were male. The median age was 20 with range of 0.75 – 70 year old. Out of those exposed 12/35 giving an attack rate of 34.3%. Two people died out of twelve cases hence case fatality rate of 16.7%. All the cases and contacts were from 3 villages of Nkoirero, Ololopili and Oltepesi were affected. The two fatal cases were from Ololopili village where the goat had died. Ololopili had 16 cases and contacts, Oltepesi had 15 while Nkoirero had 4.  


On 4 November 2018, the goat was found dead within the manyatta at 6:00 am. Skinning and butchering was done at 10:00am and meat was cooked and consumed during lunch hour. On November 7 2018, a boy 16 years old started complaining abdominal pain and vomiting and visited a private dispensary on the same.  On November 8 2018, a female 57 years old who was the mother to the boy started complaining of fever, headache and abdominal. The two were referred to Narok county referral hospital where they were admitted. They later died on November 13 2018 at the same facility.


Figure 1: Epicurve of cases showing the dates of onset and disease outcomes

Clinical information

Among those who fell sick, index case were reported on November 7 2018, at Ololopili village. The mean of incubation period was - days ranging between 3-10 days. Abdominal pain 50% (6/12), skin lesions 30% (4/12) and diarhoea 41.7% (5/12). The common route of infection was through consumption of meat from the dead goat.


KAP survey: Socio-demographic characteristics 

The KAP survey respondents were 328 of which 72.9% (240/329) were female. The mean age was 40.3 ±13.7 years with majority being aged above 35 years, 56.2% (185/329).However during the FGD males were 60%(30/50).They have kept livestock for an average of 33.5±17.2 years. Most respondents 80.7% (263/329) had no formal education with only 11.9% (39/329) having primary education. Farmers (livestock keepers) were the majority at 72.4% (236/329) followed by self-employed at 22.7% (74/329). This agrees with the key informant reports that the community’s means of livelihood is livestock keeping and tourism activities since the ward borders the Maasai Mara national park


In terms of the types of livestock kept, almost all 99.9% (328/329) households kept cattle at 98.5% (324/329), sheep 97.6 % (321/329) and goats 96.1% (316/329). 


Knowledge of anthrax signs and symptoms

Based on the KAP survey data, 88.5% (291/329) of the respondents had heard of disease anthrax. A male participant from ololopili told us the local name for anthrax is “Empuruo” he however said Few of the KAP survey respondents were knowledgeable of major signs and symptoms in animals dying from anthrax such as; sudden death 4% (14/345), bloating 28% (98/345) rapid decomposition 5% (18/345), lack of rigor mortis 8%(26/345) and bleeding from body orifices 62% (214/345). About 22% (75/345) of respondents were not aware of any signs. During the FGD most of the participants only knew of bloating “kufura kwa mnyama” and sudden death of animals as the major signs of anthrax in animals.

The following signs and symptoms were identified in human: skin lesions 95% (329/345), diarrhoea 9% (31/345), severe cough 0.9% (3/345). Slightly more than half of the respondents 57.6% (197/329) considered themselves not well informed of the disease and desired more information.  


Community Sensitization

Together with county health and veterinary services the team visited four villages where public baraza was held. Members of public mostly targeting livestock farmers were sensitized on the issues of anthrax. The risk involved, control measures and what to do in case one feels unwell.

The veterinary services office was urged to consider provision of livestock vaccines and medication for other diseases of livestock.  From the baraza, it was visible that the members of public had concern on anthrax disease and was willing to participate in the advised control measures.

The study has demonstrated human anthrax cases are preceded by animal anthrax cases. Males predominated in the exposed persons and 57.1% of suspected anthrax cases. Gastrointestinal form of anthrax was accounted for almost half of the suspected cases. During the investigation no deaths were reported except the 2 initial cases that represented 16.7% case fatality rate contrast to common finding of 2% among cases in endemic areas. All the cases and exposed persons sought medical attention in a health facility. Of all affected patients 64.1% of the suspected cases had exposure through consumption of meat while other forms of exposure such as such as skinning of dead animal, chopping and cooking of meat had a small proportion.  The study found most respondents had no formal education (80.7%) while only 11.9% had primary education. Education influences one's access to information and ability to comprehend health messages.  


The suspected outbreak occurred in November which generally a hot month was including October up to July when we had prolonged rains.


Figure 2: Map showing the outbreak villages and their locations in the ward, county and Kenya