Molecular detection and characterization of pathogenic Leptospira species in bats (Chiroptera) roosting in human habitats in Nigeria, West Africa

Leptospirosis is a neglected zoonosis with a nearly global distribution. In order to determine the role of bats in the epidemiology of leptospirosis in Nigeria, a total of 231 bats belonging to three families, Pteropodidae (n = 117), Molossidae (n = 107) and Nycteridae (n = 17), roosting in human habitats were screened by PCR and sequencing for the detection of pathogenic Leptospira species. DNA extracted from the kidneys of bats were subjected to conventional PCR targeting the rrs1, rrs2, flaB and secY genes for the detection of pathogenic Leptospira spp. Overall, 27 out of the 231 (11.7%) of the samples screened were positive for Leptospira spp. High prevalence (>80%) of Leptospira spp. DNA was detected in Chaerophon and Nycteris bat species captures in an abandoned well located within a human habitation. Sequences generated in this study were highly identical to Leptospira borgpetersenii and Leptospira interrogans and clustered with sequences of pathogenic species in GenBank. The detection of pathogenic Leptospira spp. was significantly associated (p < .001) with the bat species, feeding habit, roosting site and study location. To the best of our knowledge, this is the first molecular detection and characterization of pathogenic Leptospira spp. in bats from Nigeria. Results show that bats in Nigeria are infected with diverse Leptospira genotypes phylogenetically related to known pathogenic, including zoonotic taxa. Together, these findings reinforce bats' roles as potential reservoirs of Leptospira spp. and should be considered as a starting point for future comparative studies to improve our understanding of the epidemiology of this bacterial pathogen in Nigeria.

Comparative performance of lateral flow immunochromatography, iELISA and Rose Bengal tests for the diagnosis of cattle, sheep, goat and swine brucellosis

BACKGROUND

Brucellosis is a world-wide extended zoonosis that causes a grave problem in developing economies. Animal vaccination and diagnosis are essential to control brucellosis, and the need for accurate but also simple and low-cost tests that can be implemented in low-infrastructure laboratories has been emphasized.

METHODOLOGY

We evaluated bovine, sheep, goat and swine lateral flow immunochromatography assay kits (LFA), the Rose Bengal test (RBT) and a well-validated protein G indirect ELISA (iELISA) using sera of Brucella culture-positive and unvaccinated brucellosis free livestock. Sera from cattle vaccinated with S19 and RB51 brucellosis vaccines were also tested. Finally, we compared RBT and LFA using sera of white Fulani cattle of unknown bacteriological status from a brucellosis endemic area of Nigeria.

RESULTS AND CONCLUSIONS

Although differences were not statistically significant, RBT showed the highest values for diagnostic sensitivity/specificity in cattle (LFA, 96.6/98.8; RBT, 98.9/100; and iELISA, 96.6/100) and the iELISA yielded highest values in sheep (LFA, 94.0/100; RBT, 92.0/100; iELISA, 100/100), goats (LFA, 95.7/96.2; RBT, 97.8/100; iELISA, 100/100) and pigs (LFA, 92.3/100; RBT, 92.3/100; iELISA, 100/100). Vaccine S19 administered subcutaneously interfered in all tests but conjunctival application minimized the problem. Although designed not to interfere in serodiagnosis, vaccine RB51 interfered in LFA and iELISA but not in the RBT. We found closely similar apparent prevalence results when testing the Nigerian Fulani cattle by RBT and LFA. Although both RBT and LFA (showing similar diagnostic performance) are suitable for small laboratories in resource-limited areas, RBT has the advantage that a single reagent is useful in all animal species. Considering these advantages, its low cost and that it is also useful for human brucellosis diagnosis, RBT might be a good choice for resource-limited laboratories.

Wealth, household heterogeneity and livelihood diversification of Fulani pastoralists in the Kachia Grazing Reserve, northern Nigeria, during a period of social transition

Background

A mixed methods study was undertaken in the Kachia Grazing Reserve of northern Nigeria. Surveys in March, June and October 2011 included focus group discussions, key informant and in-depth household interviews, concerning livelihood practices, animal health, ownership, and productivity. In May 2011, 249 Fulani families fleeing post-election violence entered the reserve with their livestock, increasing the number of households by one third.

Results

Despite being settled within a grazing reserve, over half of households sent all their cattle away on seasonal transhumance and another third sent some away. Cattle accounted for 96% of total tropical livestock units (TLU), of which 26% were cattle kept permanently outside the reserve. While all households cited livestock as their main source of income, 90% grew crops and 55% derived income from off-farm activities. A multiple correspondence analysis showed that for each extra member of a household its TLU value increased by 2.0 [95% CI, 1.4–2.7], while for each additional marriage its TLU increased by 15.7 [95% CI, 7.1–24.3]. A strong association was also observed between small herds, small households with only one wife, alongside marked geographical wealth differences within the reserve. New immigrant families had larger household sizes (33) and livestock holdings (122 TLU) than old settlers (22 people and 67 TLU). Prior to the mass immigration, the distribution of TLU per person was unimodal: 41% of households were classified as ‘poor’ and 27% as ‘medium’, whereas post-immigration it was bi-modal, with 26% classified as ‘very poor’ and 28% as ‘medium’.

Conclusions

While cattle remain the principal source of Fulani income and wealth, the inhabitants of Kachia Grazing Reserve have diversified their livelihood strategies to respond to changing circumstances and stress, especially the limited availability of grazing within the reserve and political insecurity outside, resulting in continued transhumance, the maintenance of smaller livestock holdings and pushing households into poverty.

Brucellosis as an emerging threat in developing economies: lessons from Nigeria

Nigeria is the most populous country in Africa, has a large proportion of the world's poor livestock keepers, and is a hotspot for neglected zoonoses. A review of the 127 accessible publications on brucellosis in Nigeria reveals only scant and fragmented evidence on its spatial and temporal distribution in different epidemiological contexts. The few bacteriological studies conducted demonstrate the existence of Brucella abortus in cattle and sheep, but evidence for B. melitensis in small ruminants is dated and unclear. The bulk of the evidence consists of seroprevalence studies, but test standardization and validation are not always adequately described, and misinterpretations exist with regard to sensitivity and/or specificity and ability to identify the infecting Brucella species. Despite this, early studies suggest that although brucellosis was endemic in extensive nomadic systems, seroprevalence was low, and brucellosis was not perceived as a real burden; recent studies, however, may reflect a changing trend. Concerning human brucellosis, no studies have identified the Brucella species and most reports provide only serological evidence of contact with Brucella in the classical risk groups; some suggest brucellosis misdiagnoses as malaria or other febrile conditions. The investigation of a severe outbreak that occurred in the late 1970s describes the emergence of animal and human disease caused by the settling of previously nomadic populations during the Sahelian drought. There appears to be an increasing risk of re-emergence of brucellosis in sub-Saharan Africa, as a result of the co-existence of pastoralist movements and the increase of intensive management resulting from growing urbanization and food demand. Highly contagious zoonoses like brucellosis pose a threat with far-reaching social and political consequences.

Serological evidence for brucellosis in Bos indicus in Nigeria

PURPOSE

Nigeria is the largest cattle-rearing nation in Africa with most animals kept under traditional husbandry practices. While bovine brucellosis does not receive much attention, a relatively high seroprevalence is found in samples submitted for laboratory testing. The aim of the study was to provide serological evidence of brucellosis in cattle from some of the main cattle-rearing states of the country and to validate a simple and rapid field test for the serodiagnosis of bovine brucellosis.

METHOD

Serum samples collected in various states of Nigeria from cattle because of suspicion of brucellosis were investigated in the Rose Bengal plate test, and results were compared with a newly developed rapid field test for the detection of Brucella-specific antibodies.

RESULTS

Serological evidence for the presence of brucellosis in cattle was obtained for all states included in the study and a high herd prevalence was observed. The seroprevalence was also high among trade and slaughter animals. Results of a rapid field test for the serodiagnosis of bovine brucellosis correlated well with the Rose Bengal plate test (agreement, 95.7%; kappa value, 0.80).

CONCLUSIONS

The results indicate that bovine brucellosis is an important veterinarian problem in Nigeria. The easy-to-use and robust field test is most promising for field-based surveillance as it provides an immediate result allowing the prompt instigation of control measures.

Serologic prevalence of brucellosis in horse stables in two northern States of Nigeria

Despite the endemicity of brucellosis in Nigeria, reports on equine brucellosis are rare. The Rose Bengal Plate Test (RBPT) was used to determine the serologic prevalence of Brucella abortus antibodies amongst 75 horses from three stables in two States of northern Nigeria. The highest prevalence (22.7%) was recorded in stable C located in Plateau State and the lowest (6.7%) was found in stable B in Kaduna State. The overall prevalence determined was 14.7%. There is need for the inclusion of horses in brucellosis surveillance and control strategies in Nigeria to safeguard people at high risk.

Abortion due to Brucella abortus in sheep in Nigeria

This paper reports on a sporadic, naturally acquired infection of sheep with Brucella abortus on a privately owned farm in Toro near Bauchi, Nigeria. The abortions, which occurred in a flock of 28 Yankassa sheep, involved five ewes at the third month of gestation. Serum and milk samples from the flock were examined for Brucella antibodies by the Rose Bengal plate test, serum agglutination test (SAT) and milk ring test (MRT). The proportion shown as positive by SAT was 14.3%. All the five milk samples examined by MRT were positive. A total of seven isolates of Brucella were obtained from three milk samples and four vaginal swabs collected from aborting ewes. All isolates were identified and biotyped as B. abortus biovar 1. This biovar was also isolated from cattle maintained on the farm in association with the sheep. The infection was attributed to the animal husbandry practices employed on the farm.

Phenotypic characterization of Brucella strains isolated from livestock in Nigeria

Isolation of brucellae from aborted fetuses, hygroma fluids, milk and vaginal swabs obtained from aborting cattle, sheep, goats, pigs, and horses in Nigeria was carried out. A total of 25 isolates, obtained mainly from cattle, sheep and horses, were biotyped. All strains belonged to one species, Brucella abortus biovar 1. The epidemiological significance of this finding is discussed. Some preliminary observations on the zoonotic and public health implications of Brucella infection in Nigerian livestock are presented. A control programme involving improved management, animal movement restrictions, public health education and mass vaccination of animals is suggested.

Use of the enzyme-linked immunosorbent assay for screening cattle for Brucella antibodies in Nigeria

The prevalence of Brucella antibodies in settled Fulani cattle herds in Kaduna State, Nigeria, was determined by using the enzyme-linked immunosorbent assay (ELISA) technique. Out of a total of 762 animals drawn randomly from 40 cattle herds in various areas of the state, 50 (6.6%) tested positive. There was no significant difference (P<0.01) in the number of reactors between male and female animals. Brucella antibodies were detected in animals in all areas of the state but prevalence was highest in Kaura area (26.8%) and was lowest in Zonkwa area (1.0%). Out of the 762 animals, 23 (3.0%) tested positive in the agglutination test (SAT) while 16 (2.1%) tested positive in the Rose-bengal plate test (RBTP). This study indicated that cattle in Nigeria have antibodies to Brucella tested by ELISA technique and that seropositive animals are located in distinct foci. The identification of these pockets of infection on a nation-wide basis will be crucial for future brucellosis control programmes.

Clostridium perfringens type A enterotoxaemia in pigs: a report of five cases

Enterotoxaemia caused by Clostridium perfringens type A in five intensively managed pigs is reported. The condition was precipitated by constipative digestive disturbance. Diarrhoea was not observed in the five animals before death.

Aeromonas hydrophila as cause of hemorrhagic septicemia in a ground-hornbill (Bucorvus abyssinicus)

An acute hemorrhagic septicemia in a captive ground-hornbill (Bucorvus abyssinicus) is reported. Aeromonas hydrophila was isolated from lungs, liver, kidney, and intestines. Postmortem lesions were characterized by hemorrhages in the internal organs. Microscopically, necrotic lesions were found in the liver, lungs, and kidney. Factors that might have contributed to the clinical disease condition are discussed.

Isolation of Aeromonas hydrophila from a captive caracal lynx (Felis caracal)

Aeromonas hydrophila was isolated from the internal organs of a captive caracal lynx (Felis caracal) which died of acute septicemia. Grossly, patchy areas of focal necrosis were found in the lungs, liver and kidney; there was ulceration in the stomach and intestines. Microscopically, lesions contained cellular debris, neutrophils, lymphocytes and gram-negative bacilli. This is the first report of isolation of Aeromonas hydrophila from a captive wild animal in Nigeria.

Concurrent infection of a Patas monkey (Erythrocebus patas) by Citrobacter freundii and Trichuris trichiura

Concurrent infection of Citrobacter freundii and Trichuris trichiura in a Patas monkey (Erythrocebus patas) is reported. A synergistic effect of both organisms contributing to host mortality in this case is suggested.

An epizootic infection of Citrobacter freundii in a guineapig colony: short communication

An epizootic infection of Citrobacter freundii in a guineapig colony is reported. From 1300 guineapigs maintained in a colony, a total of 115 guineapigs died. Lesions found postmortem were suggestive of acute pneumonia and enteritis. Citrobacter freundii was consistently isolated from necropsy specimens of lung, liver, spleen and intestines of the animals. The source of infection was not ascertained.

Klebsiella pneumoniae as a cause of pneumonia and septicemia in a civet kitten (Civettictis civetta) in the Jos Zoo, Nigeria

A fatal case of acute pneumonia and septicemia that occurred in a captive civet kitten (Civettictis civetta) in the Jos Zoo, Nigeria is reported. Diagnosis was based on clinical signs, necropsy findings, and the isolation of Klebsiella pneumoniae from the lung, intestine, liver and heart blood of the animal. This is the first report of clinical K. pneumoniae infection in a wild or captive animal in Nigeria.

Fatal case of salmonellosis (Salmonella pullorum) in a chimpanzee (Pan troglodytes) in the Jos Zoo

A case of salmonellosis in a captive chimpanzee (Pan troglydytes) is reported. Confirmatory diagnosis was based on clinical signs, necropsy and histopathological examination, and the isolation of Salmonella pullorum from the lung, liver, kidney and intestines of the animal. The source of infection was not ascertained.