Serological and molecular epidemiology of leptospirosis and the role of dogs as sentinel for human infection in Nigeria

Objective

Prospective cross-sectional study of dogs in Nigeria to study leptospirosis, inferred to be endemic in all regions of the country by researchers. Aim is to generate empirical updated evidence of leptospiral infection and delineate serovars involved.

Methods

Study determined the sero-prevalence and infection rate in 342 dogs using sero-assays, culture isolation and novel qPCR. In-house designed primers targeting conserved regions were used to amplify genes in quantitative Real-Time PCR (qRT-PCR) for leptospiral detection to serogroups. Molecular analysis of the leptospiral 16S rRNA and LipL32 genes were used for identification of pathogenic Leptospira species. Primers targeting the O-antigen (rfb) region of the Leptospira lipopolysaccharide (LPS) were used for differentiating serovars based on comparative melting temperature (T_m) analysis against reference serogroups.

Results

Overall serological and bacteriological prevalence of 56 (16.4%) and 40 (11.7%) respectively was recorded. Vaccination, ages and season(s) were the strongest determinants of infection. Unvaccinated animals, stray dogs and symptomatic dogs presented statistically significant (P < 0.05) higher risk of infection: OR 25.531 (6.108, 106.712; 95% CI).

Discussion

The evidence suggests 1 of every 10 dogs is infected and could be symptomatic for the disease or a carrier of leptospires in the studied region in Nigeria with attendant public health risks.

First molecular description, phylogeny and genetic variation of Taenia hydatigena from Nigerian sheep and goats based on three mitochondrial genes

BACKGROUND

Cysticercosis caused by the metacestode larval stage of Taenia hydatigena is a disease of veterinary and economic importance. A considerable level of genetic variation among isolates of different intermediate hosts and locations has been documented. Generally, data on the genetic population structure of T. hydatigena is scanty and lacking in Nigeria. Meanwhile, similar findings in other cestodes like Echinococcus spp. have been found to be of epidemiological importance. Our aim, therefore, was to characterize and compare the genetic diversity of T. hydatigena population in Nigeria based on three mitochondrial DNA markers as well as to assess the phylogenetic relationship with populations from other geographical regions.

METHODS

In the present study, we described the genetic variation and diversity of T. hydatigena isolates from Nigerian sheep and goats using three full-length mitochondrial genes: the cytochrome c oxidase subunit 1 (cox1), NADH dehydrogenase subunit 1 (nad1), and NADH dehydrogenase subunit 5 (nad5).

RESULTS

The median-joining network of concatenated cox1-nad1-nad5 sequences indicated that T. hydatigena metacestodes of sheep origin were genetically distinct from those obtained in goats and this was supported by high F_ST values of nad1, cox1, and concatenated cox1-nad1-nad5 sequences. Genetic variation was also found to be higher in isolates from goats than from sheep.

CONCLUSIONS

To the best of our knowledge, the present study described the genetic variation of T. hydatigena population for the first time in Nigeria using full-length mitochondrial genes and suggests the existence of host-specific variants. The population indices of the different DNA markers suggest that analysis of long mitochondrial DNA fragments may provide more information on the molecular ecology of T. hydatigena. We recommend that future studies employ long mitochondrial DNA sequence in order to provide reliable data that would explain the extent of genetic variation in different hosts/locations and the biological and epidemiological significance.

Disseminated tuberculosis in a cow and a dromedary bull-camel in Zamfara State in Nigeria

In 2017, cases of generalized tuberculosis (TB) were identified in a cow and a bull-camel, slaughtered at the Gusau abattoir in Zamfara State Nigeria. The objective of this study was to identify the cause of the gross pathology on the account of disseminated lesions widely distributed in different body parts of the animals. Tissue samples were analysed using Ziehl-Neelsen (ZN) stain and region of difference (RD) deletion typing. Results obtained by laboratory investigations revealed infection with acid-fast tubercle bacilli in affected tissues from the cow and the dromedary bull-camel. This study presents the first molecular evidence of Mycobacterium bovis infection in a Nigerian dromedary camel, demonstrated the ease of identification of the acid-fast bacilli using molecular method which improves diagnosis and can aid epidemiological studies.

Seroprevalence of foot and mouth disease virus infection in pigs from Zuru, Nigeria

Aim:

This study was conducted to determine the seroprevalence and distribution of foot and mouth disease virus (FMDV) infection in pigs from Zuru, Kebbi State, Nigeria.

Materials and Methods:

Cross-sectional serological surveys were conducted between May and December 2013 using the immunochromatography assay technique. Structured questionnaires were administered to households identified at pig rearing areas to obtain the population structures and some information on managemental practices.

Results:

A total number of 849 pigs were enumerated at 37 pigs rearing households. Tudun wada had the largest concentration of pigs (237 pigs), while Dabai has the least (38 pigs). A total of 250 blood samples were collected, of which 45 (18%) were positive; Zango has the highest seroprevalence (1.6%), while Dabai recorded the least (0.4%). Based on sex and age, the infection was higher in female (10.4%) and young pigs (11.6%) than male (7.6%) and adult pigs (6.4%), respectively. There was no significant (p>0.05) association between infection and pig rearing areas, sex, and age. Furthermore, none of the 250 pigs examined for classical FMDV lesions was positive.

Conclusion:

The results of this study showed that FMD is an important disease of pigs in the study areas. This result justifies the need for more attention and subsequent molecular study to identify the circulating FMDV in the area, which will help in the implementation of effective control measures.

Survey of thermophilic Campylobacter species in cats and dogs in north-western Nigeria

This study was conducted in north-western Nigeria to investigate the role of cats and dogs as potential reservoirs of thermophilic Campylobacter species. Faecal samples were analysed from 104 cats and 141 dogs between March 2007 and March 2009. The samples were collected from animals in households, those presented to veterinary premises and feline colonies. Campylobacter spp. were isolated from 39 (27.7%) and 19 (18.3%) dogs and cats, respectively. There was no significant difference in isolation rate observed between dogs (27.7%) and cats (18.3%) and there was also no significance difference between younger and older dogs; 23.1% (young) compared to 30.3% (older) dogs, but a significant difference was seen between young (4.3%) and older (29.3%) cats. Campylobacter upsaliensis predominated in the isolates, accounting for 89.5% and 74.4% of the positive samples in cats and dogs, respectively, C. jejuni constituted 21.1% and 23.1% of the positive samples from cats and dogs, respectively. This finding is an indication that dogs and cats frequently shed thermophilic Campylobacter spp. which could be of public health importance. To establish the zoonotic significance of canine and feline Campylobacter, isolates need to be further characterised and compared. This is the first study on the prevalence of campylobacter in cats and dogs in the region.

Isolation and prevalence of Campylobacter species in cattle from Sokoto state, Nigeria

The prevalence of Campylobacter spp. in cattle in Sokoto State, Nigeria, was determined. The number of samples collected totalled 976, of which 126 (12.9%) yielded Campylobacter spp. The species of Campylobacter isolates from this study were as follows: C. jejuni (65.1%), C. coli (23.0%), C. lari (7.9%), C. hyointestinalis (3.2%) and C. fetus (0.8%). A total of 172 strains of Campylobacter spp. were identified from the positive samples due to identification of more than a single strain (spp.) from a single sample. The strains identified were C. jejuni (62.8%), C. coli (25.0%), C. lari (8.1%), C. hyointestinalis (2.9%) and C. fetus (1.2%). More than one species of Campylobacter was identified in 36.5% of the positive samples. The biotyping in this study revealed C. jejuni biotype I (34.3%) as the most common C. jejuni biotype, while C. jejuni biotype IV (15.7%) was the C. jejuni biotype that was least frequently isolated. However, the most frequently isolated C. coli biotype was biotype I (72.1%) and all the isolates of C. lari were biotype I.

A survey of veterinary hospitals in Nigeria for the presence of some bacterial organisms of nosocomial and zoonotic potential

This study was undertaken to determine the type and estimate the prevalence of bacterial organisms on contact surfaces of five close-to-patient facilities in three veterinary health care settings within the Sokoto metropolis of north-western Nigeria. A total of 30 samples (10 from each setting) were collected and analysed using culture, microscopy and biochemical testing. Bacterial species isolated from samples in this study included the following: Bacillus sp. (27.3%), Staphylococcus aureus (15.9%), Listeria sp. (13.6%), Streptococcus sp. (11.4%), Salmonella sp. (6.8%), Escherichia coli (4.5%), Staphylococcus epidermidis (4.5%), Citrobacter sp. (2.3%), Klebsiella sp. (2.3%), Lactobacillus sp. (2.3%), Micrococcus sp. (2.3%), Pasteurella sp. (2.3%), Proteus sp. (2.3%), and Yersinia sp. (2.3%). A higher percentage (64.3%) of the total bacterial isolates were zoonotic in nature and hence of public health significance. Some pathogens have the potential of nosocomial spread. In this study, we seek to establish the first evidence of bacterial presence in the major veterinary health care settings in the Sokoto region of north-western Nigeria. Of particular interest is the hypothesis, which has not previously been formally tested, that nosocomial infections are especially likely to be implicated in both animals and occupational diseases in Nigeria. It was suggested that some of these isolates were associated with the risk of nosocomial and zoonotic infections and hence draws attention to the need to rigorously employ standard veterinary precautions as part of the hospital's infection control programme in an attempt to protect both patients and staff from infections.