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DIAGNOSIS AND EPIDEMIOLOGY OF ZOONOTIC NONTUBERCULOUS MYCOBACTERIA AMONG DROMEDARY CAMELS AND HOUSEHOLD MEMBERS IN SAMBURU COUNTY, KENYA
(2020-09) LUCAS LUVAI AZAALE ASAAVA
Zoonotic nontuberculous Mycobacteria (NTM) cross infect a wide range of
domestic animals, wildlife and man causing various diseases. Despite the public
health implications associated with mycobacterial infection and the existing close
interaction of pastoralists and camels, information on diagnosis and epidemiology of
zoonotic NTM amongst camels and closely associated community members is
scanty. The present study was a one-health approach study involving diagnosis and
epidemiology of zoonotic NTM infection among dromedary camels and associated
household members in Samburu East sub-county. The study was cross sectional
covering camels slaughtered at county abattoirs as well as household members and
camels. Abattoirs sampled included Isiolo and Athi-River camel abattoirs, where all
sampled camels were confirmed to have come from Samburu east. Household camel
sampling strategy involved stratification of the study area to Wamba and Waso
rearing areas. Sampling at abattoirs was consecutive for camels identified to have
TB-like lesions during meat inspection. People presumed to have TB from amongst
the sampled households were requested to provide a sputum sample. Screening of
lactating camels for Mycobacteria infection was done using single intradermal
comparative tuberculin test (SICTT) in a consecutive sample of 612 lactating camels
from 83 households. A consolidated milk sample from all four mammary quarters
was collected from 238 tuberculin test reactive camels. Post mortem (PM)
examination was conducted on 1600 camels originating from the study area. A semistructured questionnaire was administered to collect data on risk factors from 83
respondents. All milk, sputum and tissue samples were analysed at Kenya Medical
Research Institute (KEMRI)/Centre for Respiratory Disease Research (CRDR)
enhanced BSL2 laboratory using mycobacteriology, molecular speciation using
GenoType® Mycobacterium line probe assay (HAINLifescience), drug
susceptibility testing, 16S rDNA sequencing and phylogenetic analysis. This study
was conducted between April, 2017 and December, 2018. Results indicated that the
proportion of M. bovis and M. avium reactors was estimated at 6.05% and 39.38%
respectively. Out of 238 milk samples, 57 (23.95%) had culture positive acid fast
bacilli (AFB). Out of 132 suspected lesions on PM, 27/1600 1.69% (binomial 95%,
CI: 1.11%-2.45%) were AFB positive on culture. Of the 48 sputum samples, 7 were
AFB culture positive. The NTMs were observed to occur widely in various samples
analysed, including post mortem lesions: M. fortuitum 17/27 (62.96%), M.
scrofulaceum 3/27 (11%), M. szulgai 2/27 (7.4%); camel milk samples: M. szulgai
20/57 (35.09%), M. monacense 5/57 (8.77%), M. litorale 4/57 (7.02%), M. fortuitum
3/57 (5.26%), M. lehmannii 3/57 (5.26%), M. elephantis 3/57 (5.26%), M. duvalii
3/57 (5.26%); and in Human sputum samples: M. fortuitum 1/48 (2.08%), M. szulgai
2/48 (4.16%), and M. litorale 1/48 (2.08%) among others. These findings
demonstrate high levels of infection with NTM in both humans and camels. Camel
post mortem analyses revealed bronchial, mediastinal lymph nodes and lung lobes
were most affected tissues. Several NTMs of medical importance with varying level
of commonly used TB drugs sensitivity. The pattern of resistance to first-line TB
drugs was as follows: Isoniazid (100%), rifampicin (97.9%) and ethambutol
(65.3%). All NTM species isolated were highly resistant to first-line TB drugs.
Camel breed, age, production system, origin of new introductions, migration and
herd size were identified as risk factors for infection in camels (p<0.05).
Surveillance and notification systems for NTMs including specific immunological
test for NTMs diagnoses are needed. The public health significance of NTM in
camels and humans needs further unravelling.
INSECTICIDE RESISTANCE AND ITS IMPACT ON MALARIA TRANSMISSION POTENTIAL AMONG THE MAJOR VECTORS IN TESO SUB – COUNTIES, WESTERN KENYA
(2020-11) GITHINJI EDWARD KAREITHI
In Africa, knockdown resistance (kdr) is strongly linked to pyrethroid insecticide resistance in Anopheles gambiae s.l; which may have vital implications to the current up-scaled indoor residual spraying (IRS) and pyrethroid-treated bed net campaigns. This investigation proposed to evaluate the extent and levels of insecticide resistance among major vectors in Teso North and South sub counties, western Kenya, and its impact on entomological parameters of malaria transmission. For WHO phenotypic susceptibility tube assay, mosquito larvae were sampled using a dipper, reared into 3-5 days-old females which were exposed to 0.75% permethrin, 0.05% deltamethrin and 0.1% bendiocarb. Random sampling of adult mosquitoes [3448] was done using adult mosquito sampling methods. Abdominal statuses, parity rates, age grading and molecular species identification were recorded. Kdr East TaqMan PCR probed for the mutant allele and wild type. Sporozoite ELISA detected circum-sporozoite protein. Anopheles gambiae sensu stricto were the significant majority in terms of species composition at 78.9% as compared to Anopheles arabiensis (20.7%) [t (4, 4) = 11.1268, p < .05]. Highest proportion of SS alleles (86.1%) was also found among Anopheles gambiae sensu stricto mosquitoes. Susceptible Kengatunyi cluster had higher proportion of An. arabiensis than resistant Rwatama. Bendiocarb caused 100% mortality while deltamethrin had higher insecticidal effects (77%) on female mosquitoes than permethrin (71%). There was a significant difference in SS allele frequencies between Kengatunyi (57.8%) and Rwatama (93.4%). Of the parous vectors, 75.6% were homozygous resistant, 2.4% were heterozygous and 22% were homozygous susceptible. Mosquitoes in the resistant cluster had an average lifespan of 16 days compared to 5 days in the susceptible cluster. Resistant clusters had
the largest number of infective bites per person per night at 0.4. Of the sporozoite positive
mosquitoes, 71.4% were homozygous resistant and the rest homozygous susceptible. Heterozygous LS allelic vectors had significantly higher affinity for bovine blood while SS allelic vectors had significant higher affinity for human blood. All SS, LS and LL carriers were biting more at dawn than at dusk. All results were significant at p<0.05. Most likely, the higher the selection pressure exerted indoors by insecticidal nets the higher were the resistance alleles. Use of pyrethroids impregnated nets and agrochemicals may have caused female mosquitoes to select for pyrethroid resistance, consequently impacted on species composition and behaviour patterns. Confirmed phenotypic and genotypic insecticide resistance in major malaria vectors in Teso North and Teso South sub counties, impacted significantly on vector species composition, age structure, density, infectivity, feeding and resting behaviours. Insecticide resistance management practices in Kenya should be fastracked and harmonised with agricultural sector agrochemical based activities and possibly switch to carbamate usage. The implication of such high resistance levels in the mosquitoes is that resistance is likely to persist and or even increase if mono-molecules of permethrin and deltamethrin or both continue to be used in all net and non-net based mosquito control purposes. Piperonyl butoxide (PBO) that prohibit certain metabolic enzymes within malaria vectors and has been combined into pyrethroid-LLINs to create pyrethroid-PBO nets, may be an extremely viable option against the spread of insecticide resistance in Kenya.
EFFECTS OF PROBIOTICS ON GROWTH, FLESH QUALITY AND HEMATOIMMUNOLOGICAL STATUS OF CULTURED NILE TILAPIA (Oreochromis niloticus) IN KIRINYAGA COUNTY, KENYA
(2026-08) OPIYO, MARY ADHIAMBO
Nile tilapia (Oreochromis niloticus) culture in Kenya is mainly conducted in low input
ponds where supplementary feed is given alongside pond fertilization. Excess nutrients in
the culture water in form of nitrogen (N) and phosphorus (P) may make the culture
environment susceptible to invasion by disease-causing microorganisms. In the recent past,
probiotics have received much attention as a new strategy in fish health management and
have been documented to improve fish growth performance and immunity in fish cultured
in recirculating systems. However, their effect in tilapia cultured in low input ponds is still
relatively unknown. In this study, monosex O. niloticus fingerlings with a mean weight of
39.75 ± 0.05 g were randomly stocked at 50 fish m-3 in 1.25 m3 cages in low input earthen
ponds. The fish were fed twice daily at 3% body weight on seven isonitrogenous (28%
crude protein) diets supplemented with either Saccharomyces cerevisiae (1×1010 CFU g-1)
or Bacillus subtilis (1×109
CFU g-1) at different levels as follows: No probiotic (Diet 0); S.
cerevisiae at 2 g kg−1 (Diet 1), 4 g kg−1 (Diet 2) and 6 g kg−1 (Diet 3); and B. subtilis at 5 g
kg−1 (Diet 4), 10 g kg−1 (Diet 5) and 15 g kg−1 (Diet 6) for a period of 7 months. The fish
were sampled monthly for weight and length measurements. Hemato-immunological
parameters were determined by blood sampling and hematological analysis for red blood
cells, white blood cell and haemoglobin counts. Blood serum assay was conducted using
commercial enzyme-linked immunosorbent assay (ELISA) kits to determine the serum
protein, albumin, globulin levels and lysozyme activity. Microbiological samples were
analyzed through sub-culturing to obtain pure cultures on nutrient media and enumerated
through standard methods. Results of the trials indicated that the highest performance was
achieved with Diet 2. The highest final weight (255.31 ± 3.19 g), Specific growth rates
(SGR) (0.77±0.01% day-1) and feed conversion ratio (FCR) (1.61 ± 0.02) were recorded in
fish fed Diet 2. This was followed by fish fed Diet 5. Results of growth performance
analysis indicated that fish fed on probiotic-supplemented diets had significantly better
growth, nutrient utilization and FCR than fish fed on the control diet (P < 0.05). Probiotic
supplementation significantly affected the body composition of the fish (P < 0.05).
Saccharomyces cerevisiae at 4 g kg-1 (Diet 2) led to significantly high protein (86.06%) (P
< 0.05) while B. subtilis at 5 g kg-1 (Diet 4) led to significantly higher protein (89.40%) (P
< 0.05). Crude lipid and ash content were significantly lower in the fish fed probioticsupplemented diets (P < 0.05) compared to the control. Results of hemato-immunological
analysis indicated that haemoglobin (Hb), red blood cells (RBC), white blood cells (WBC),
serum protein, albumin, globulin and lysozyme activity were higher in fish fed on
probiotic-supplemented diets and lower in the control group (Diet 0). Probiotic
significantly affected hemato-immunological parameters (P < 0.05). Fish fed on probioticsupplemented diets retained the probiotics in their guts and had lower microbial load in
their muscle (P < 0.05). This study shows that incorporation of probiotics in diets of Nile
tilapia in low input ponds promotes growth performance, enhances body composition,
improves immunity and manipulates gut microbiota of fish. The two probiotics differ in
effect at different levels of application. Probiotic S. cerevisiae exhibited the best
performance at 4 g kg-1 while B. subtilis had the best performance at 10 g kg-1. Probiotics
are therefore recommended for use in low input fish culture systems for better nutrient
utilization, higher yields and improved fish health for increased aquaculture production.
CHARACTERIZATION AND CONTROL OF PATHOGENIC PARASITES IN NILE TILAPIA (OREOCHROMIS NILOTICUS LINNAEUS 1758) IN FISH FARMING SYSTEMS
(2020-10) DAVIES MUKWABI MAKILLA
In Kenya, fish farming has been expanding in recent years, with Government support
through financial and input subsidies to small scale farmers. The sub sector generates
a variety of benefits such as food and nutrition and develops trade. However, the sub
sector faces the challenges of fish diseases, given that the fish production facilities
support high-density living conditions that are favorable for spread of parasitic
diseases. Besides, when fish that is infected is consumed by humans, the humans may
be infected, especially when eaten fresh. Infected fish lowers their market value and
sunctions may also be imposed on fish exports. Knowledge of fish parasites in
aquaculture systems as well as treatment options available would enlighten fish
farmers on the specific actions to take in order to harvest quality fish. The study was
cross sectional carried out in Bungoma County from August 2015 to Decemebr 2017.
The main objective of the study was to characterize and evaluate control options of
pathogenic parasites present in fish farming systems in Bungoma County. Bungoma
County was chosen for this study because it is one of the Counties that has high
potential for fish farming. The County hosts one out of the public fish farms and
hatcheries at Chwele besides authenticated private fish hatcheries. He hatcheries are
sources of fish fingerlings as well as training and demonstration centres for fish
farmers. At every fish pond, six water quality parameters were assessed using a
portable auto sampler. Farmed Nile tilapia was randomly sampled to determine the
pathogenic parasites and bacteria present in various organs. Commercial fish feeds
were also purchased from two fish feed millers in Bungoma County and assessed for
parasite presence. Polymerase Chain Reaction (PCR) and genetic sequencing analysis
were conducted in order to assess the genes responsible for antimicrobial resistance.
The data was entered into Micro Soft Excel (Windows 10) spreadsheet and analysed
by SPSS Software. It was found that there was significant difference only in
temperature of the pond water sampled across the sub counties (F=15.5; df=5;
p<0.001). Helminthes recovered were Pallisentis tetraodontis, Pallisentis spp.,
Acanthocephalus spp., Procamallanus spp. and Philometroides spp. from Nile tilapia
and Cleidodiscus spp. from pond water. Bacteria that were isolated from Nile tilapia
were Vibrio vulnificus, Vibrio parahaemolyticus, Aeromonas hydrophila, and
Pseudomonas aeruginosa. In fish pond water, Aeromonas hydrophila was isolated
while Streptococcus iniae was isolated from fish feeds. Besides, there was a
significant difference in distribution of total viable aerobic colony counts in fish
ponds water across the different sub counties (H=6;df 5; P< 0.041). Furthermore, it
was found that there was significant difference in the distribution of Aeromonas
hydrophila in fish ponds across the different sub counties (H=3;df;P< 0.016). The
external parasites were eliminated by formalin (36% formaldehyde) at concentration
of 25ppm for 1h and Hydrogen peroxide at 75ppm for 30 min. The bacterial isolates
were found to be significantly different in responses to antimicrobial agents (OLR;df=
16; P<0.00). When the bacterial isolates were subjected to PCR, all five bacterial
pathogens isolated from fish, pond water and fish feeds were found to contain blaTEM
gene amplified at 424bp. The sequences blaTEM gene returned 100% identity with
GenBank Accession number; BankIt2236899 Seq1a MN114035 to Seq 9b
MN114052). This study found that the blaTEM gene was present in recovered Vibrio
parahaemolyticus, Aeromonas hydrophila, Pseudomonas aeruginosa and
Streptococcus iniae. It is recommended that Formalin and hydrogen peroxide as well
as potassium permanganate should used to manage fish helminthes in the ponds.
Streptococcus pneumoniae SEROTYPE PREVALENCE, ANTIBIOTIC SUSCEPTIBILITY AND ASSOCIATED RISK FACTORS AMONG CHILDREN ATTENDING GERTRUDES CHILDREN’S HOSPITAL IN NAIROBI CITY COUNTY-KENYA
(2020-06) WALEKHWA MICHAEL NYONGESA
Pneumococcal disease remains the biggest killer of children living in Kenya. This
is true despite inclusion of the 10-valent pneumococcal conjugate vaccine in the
Kenya Expanded Program on Immunization. Serotype replacement, emergence of
antibiotic resistance, inaccurate laboratory diagnosis due to optochin resistant
bacterial types and a range of environmental and host related risk factors have
been touted to be the cause of these statistics elsewhere. This study sought to
establish prevalence of Streptococcus pneumoniae serotypes, antibiotic
susceptibility patterns and associated risk factors among PCV-10 vaccinated and
unvaccinated children attending Gertrude’s Childrens Hospital. A total of 206
children were recruited for this study. Nasopharyngeal swabs were the main
specimen used. Culturing and isolation of the bacteria was done on blood agar
with gentamicin and plain blood agar plates respectively. Optochin and bile
solubility (where necessary) tests were done as confirmatory assays for the
bacteria. Pneumococci serotyping was done using the Gold Standard Quellung
Reaction test while the disk diffusion method was used to asses antibiotic
susceptibility profiles. Out of the 206 subjects sampled, 20.39% (n=42) were
found to be carriers of the bacteria. About 52% (n=22) of the carriers had received
the recommended dose of PCV-10, while 48% (n=20) had not. Almost all (n=41;
19.90% of subjects) isolates contained non-vaccine type serotypes, while n=1 of
the isolates (0.49% of subjects) were both optochin resistant and untypeable.
Serotypes 28F, 6A, 11A, 3 and 7C were prevalent in both vaccinated and
unvaccinated children, whereas serotypes 23A, 17F, 35F, 48, 13 and 35B, and
23B, 20, 19B, 21, untypeable, 15B and 39 were found among unvaccinated and
vaccinated cohorts, respectively. Thirty nine (92.86%) of pneumococci isolates
were susceptible to erythromycin, 39 (92.86%) were susceptible to vancomycin, 8
(19.86%) were susceptible to oxacillin; 40 (95.24%) were susceptible to
clindamycin, 24 (57.86%) were susceptible to ceftriaxone while 18 (42.86%)
were non-susceptible. The risk of nasopharyngeal carriage decreased
insignificantly when the subject was female (odds ratio [OR]: 0.766, 95% CI:
0.388, 1.511, p-value=0.442). Children between the age of 25-36 months (OR:
1.147 (95% I: 483, 2.722) and 37-48 months (OR: 1, 95% CI: 0.286, 3.501) had
an insignificant elevated risk of nasopharyngeal carriage of the bacteria. Children
whose mothers were non-cigarrate smokers exhibited low odds of carriage (OR:
0.764 (95% CI: 0.077, 7.537; p=0.818). Serotype replacement, resistance to
penicillins and exposure to smoke were correlated with incresaed risk of
nasopharyngeal carriage. Continuous and broader epidemiological surveys should
be carried out in the entire country to accurately determine the degree of serotype
replacement and; people should be sensitised on judicious use and/or consumption
of antibiotics. Optochin test should be introduced as a routine assay in diagnosis
of Streptococcus pneumoniae in hospitals.
