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Leptospirosis is a neglected zoonotic disease of world wide public health importance.
Rodents are major reservoirs of leptospira although wetland and aquatic migratory birds
also carry and transmit leptospira. Studies on leptospirosis in fish are few in African
countries, including Tanzania, despite favourable environment and abundant reservoirs,
which can spread leptospires into aquatic habitats and infect fish. The objective of this
study was to determine the presence of Leptospira spp in fish; the prevalent Leptospira
serovars and whether they are related to serovars reported in animals; and their potential
public health risk. A Multistage sampling technique was performed
in Morogoro
municipality, Tanzania, between November- 2016 and February -2017. Before the
sampling, knowledge, attitude and practices (KAP) questionnaire was administered to
assess the awareness of people (fishermen, fish mongers) on risk factors that might lead
to the diversity of Leptospira species and water quality for pH , Dissolved Oxygen and
Temperature was measured using Meter Sensor at Sample sites in Morogoro
Municipality.Live catfish (n=193) were caught from five different locations, namely
Sokoine University of Agriculture
Magadu farm, Mzumbe University waste water
pond, Morogoro Urban Water Supply and Sanitation Authority (MORUWASA)- Mafisa
waste water ponds , Kingolwira Centre for Fish Farming and Fingering Production and
Mkindo Fish Farmers in Morogoro Urban and mvomero districts Tanzania where blood
and biopsy samples were collected. Microscopic agglutination test (MAT) was used to
detect antibody against four leptospiral antigens, including local serovars Sokoine
(serogroup
Icterohaemorrhagiae);
Hebdomadis
(serogroup
Hebdomadis);
Kenya
(serogroup Ballum) and Pomona (serogroup Pomona). Samples with MAT titers ≥ 1:160 were scored as higher values while samples with MAT titers ranging from 1:20 to1:80
were scored as lower values for seropositivity. Absence of agglutination titers was
scored as negative. All MAT samples, including the low titre samples were subjected to
PCR using Lepat and Sapro primers for the pathogenic and non-pathogenic species
(saprophytic) respectively. Tissue samples were prepared by grinding freshly obtained
kidneys of sharptooth catfish (Clarias gariepinus) for culturing in Fletchers medium.
Dark-field microscopy readings of each of the tubes were performed at first,second,
fourth, and sixth week after culturing at 20 X magnification to assess bacterial growth, of
the total 193 samples tested, 29 (15 %) were positive with MAT. The major circulating
leptospiral serovars were Pomona (11.4 %,), Kenya (1.55%), Hebdomadis (1.55%) and
Sokoine (0.52%). By using PCR methods and of the 193 samples screened, 4 (2%) were
positive for pathogenic leptospira. No isolation of leptospira was achieved from the
kidney cultures. This study
has shown a relatively
high seroprevalence 15% of
leptospirosis in common fresh water fish type, compared to warm blooded animals hence
indicate an extended public health risk, of leptospirosis to fish handlers and consumers
.To minmize leptospirosis transmission in Morogoro region, and Tanzania at large,
where the disease is little known and thus neglected, it is recommended, to increase
public awareness of leptospirosis in the general public, and particularly those groups at
risk such as farmers, livestock keepers, fishermen, sewerage and abbatoir workers.
Routine screening for leptospirosis should
be considered in people engaged with
occupational activities that increase contact with environments likely to contain
leptospires. This is especially important in situation where malaria, typhoid and other
common febrile diseases are ruled out; Isolation of leptospires from different hosts and
sources should be emphasized in order to understand the sources of infections, infecting serovars and developing a protocol
for
the diagnosis of this infectious disease
appropriate for different areas. Rapid serological tests not involving live microorganisms
for routine diagnosis is highly recommended. |
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