Chicken anemia virus: A deadly pathogen of poultry

Chicken infectious anemia (CIA) is an immunosuppressive disease that causes great economic loss in poultry industry globally. This disease is caused by chicken anemia virus (CAV), an icosahedral and single-stranded DNA virus that is transmitted both vertically and horizontally. CAV, which belongs to the genus Gyrovirus has been reported in human, mouse and dog feces. Rapid identification of different strains of gyrovirus with high similarity to CAV has heightened public concern on this virus. Clinical symptoms of this disease such as intramuscular hemorrhage, weight loss, anemia and bone marrow aplasia are prominent in young chickens, while adult chickens experience subclinical symptoms. Biosecurity measures such as good management practice and vaccination have been the most reliable control strategy against this virus. Therefore, this study reviews the current state of CAV under the following subheadings (i) Chicken anemia virus (ii) Pathogenesis of CAV (iii) Serological evaluation of host antibodies to CAV (iv) Association of Marek's disease and infectious bursa disease with CAV infection (v) Genetic diversity and phylogenetics of CAV strains (vi) Current and future vaccine strategy in the control of CAV. In conclusion, improvement on DNA and recombinant vaccines strategy could curtail the economic impact of CAV on poultry birds. Keywords: adjuvant; CAV; chicken; disease.

A review of Eimeria antigen identification for the development of novel anticoccidial vaccines

Coccidiosis is a major poultry disease which compromises animal welfare and costs the global chicken industry a huge economic loss. As a result, research entailing coccidial control measures is crucial. Coccidiosis is caused by Eimeria parasites that are highly immunogenic. Consequently, a low dosage of the Eimeria parasite supplied by a vaccine will enable the host organism to develop an innate immune response towards the pathogen. The production of traditional live anticoccidial vaccines is limited by their low reproductive index and high production costs, among other factors. Recombinant vaccines overcome these limitations by eliciting undesired contaminants and prevent the reversal of toxoids back to their original toxigenic form. Recombinant vaccines are produced using defined Eimeria antigens and harmless adjuvants. Thus, studies regarding the identification of potent novel Eimeria antigens which stimulate both cell-mediated and humoral immune responses in chickens are essential. Although the prevalence and risk posed by Eimeria have been well established, there is a dearth of information on genetic and antigenic diversity within the field. Therefore, this paper discusses the potential and efficiency of recombinant vaccines as an anticoccidial control measure. Novel protective Eimeria antigens and their antigenic diversity for the production of cheap, easily accessible recombinant vaccines are also reviewed.

Dengue virus specific Immunoglobulin G antibodies among patients with febrile conditions in Osogbo, Southwestern Nigeria

Dengue fever is becoming one of the major public health problems in the world and its distribution has been premised on the migration of people from infected regions. This study was carried out to determine the prevalence of dengue virus IgG antibody among the patients with febrile conditions attending health facilities in Osogbo metropolis, Southwestern Nigeria. The blood samples collected between July and September, 2014 were tested for Plasmodium falciparum and the sera were subsequently subjected to Enzyme Linked Immunosorbent Assay (ELISA) to detect the dengue virus IgG antibody. Of the hundred consented participants screened, 77% were sero-positive for dengue virus IgG antibody while 41% were positive for P. falciparum. Thirty-three (33%) of the participants were positive for both dengue virus IgG antibody and P. falciparum. No significant difference was found in the prevalence of dengue virus IgG antibody and malaria among the participants (P>0.05). The high prevalence of dengue virus IgG and malaria signifies the need by the government of Osun State to sensitize residents and institute urgent measures to mitigate the resultant effects of morbidity and mortality due to dengue fever and dengue hemorrhagic fever which has hitherto appeared to be alien to the area.

Urinary schistosomiasis transmission in Epe, an urban community of Southwest Nigeria

Background:

A survey of Schistosoma haematobium infection in Epe, an urban community in Lagos State, Southwest Nigeria, was carried out to ascertain the possibility that schistosomiasis, otherwise considered a rural disease, could reach urban populations.

Materials and Methods:

About 100 ml of voided urine samples from 200 pupils aged 6–13 years [109 (54.5%) males and 91 (45.5%) females], attending an Anglican primary school, Ebute Afuye, and a community primary school, Erepoto, were examined parasitologically for hematuria and S. haematobium ova following informed consent obtained from their parents/guardians. All samples were screened using polymerase chain reaction (PCR) amplification of the schistosome Dra1 gene. Fourteen Bulinus snails collected from the two sites, Ebute Afuye (6) and Erepoto (8), were screened for schistosome infection by the PCR amplification of the schistosome Dra1 gene. PCR-RFLP of the snails’ its region was analyzed for species identification and a subregion of the cox1 gene from four infected snails (two from each site) was amplified and sequenced.

Results:

In the Anglican primary school, Ebute Afuye, and community primary school, Erepoto, 16% and 29% were positive for hematuria, and 16% and 17% had schistosome ova, respectively. PCR analysis showed that 57% and 40% were positive for the infection in Anglican primary school, Ebute Afuye, and community primary school, Erepoto, respectively. PCR screening of the snails confirmed that four from Ebute Afuye and three from Erepoto were infected with schistosomes. PCR-RFLP showed that all the 14 snails were Bulinus truncatus while phylogenetic analysis of the sequenced partial cox1 gene corroborated the PCR-RFLP results.

Conclusions:

There was a high prevalence of S. haematobium infection among the participants detected by PCR, which was able to detect infection in cases otherwise shown to be negative by hematuria. We also observed that B. truncatus is one of the snail species responsible for the transmission of urinary schistosomiasis in the Epe community. For national control programs, it is very important that trends in the prevalence and intensity of schistosomiasis in urban cities be monitored.

Epidemiological evaluation of onchocerciasis along Ogun River System, southwest Nigeria

BACKGROUND & OBJECTIVE

Epidemiological studies were carried out to assess the prevalence and community microfilarial load (CMFL) of onchocerciasis after repeated annual treatment with ivermectin along Ogun river System, southwest Nigeria.

METHOD

Skin snips were taken from consented participants in 11 selected communities along the River system. The microfilarial load of the community was estimated.

RESULTS

The prevalence and CMFL varied significantly in the communities (p <0.05). The prevalence of onchocerciasis ranged from 19.1 to 45.6%, while the CMFL ranged from 0.11 to 1.03 microfilariae per skin snip. The CMFL recorded was <5 microfilariae per skin snip, i.e. recognized by WHO as threshold value in certifying the communities to be free of onchocerciasis as public health problem, thus, signifying the possibility of onchocerciasis elimination in the study area.

CONCLUSION

Efforts should therefore be intensified to achieve improved ivermectin coverage and compliance in annual ivermectin treatment in order to completely eliminate onchocerciasis as a public health problem in the studied communities.

Larvicidal efficacy of seed oils of Pterocarpus santalinoides and tropical Manihot species against Aedes aegypti and effects on aquatic fauna

Botanical larvicides have featured prominently as alternative to synthetic chemical insecticides which are less degradable and toxic to non-target organisms. The larvicidal potentials of the seed oils of Pterocarpus santalinoides and Tropical Manihot species (TMS 30572) were investigated in the laboratory against larvae of Aedes aegypti. The seed oil of each plant was extracted using n-hexane and was graded into different concentrations; 30, 60, 90, 120 and 150 ppm. The toxicity of each of the concentrations was evaluated against 3rd instar larvae of A. aegypti and tadpoles (Buffo spp) as non target aquatic fauna. Both oils were toxic to the larvae though at higher concentrations (120 ppm and 150 ppm) after 24 hours of exposure. The oil of P. santalinoides was more toxic to the larvae (LC50 104.0 ppm and LC90 184.5 ppm) than oil of TMS (LC50 113.5 and LC90 201.2) but the difference in the lethal doses was not statistically significant (P > 0.05). However, mortality was not recorded at any of the graded concentrations in both oils against tadpoles. The results therefore suggest that the seed oils of both plants could be incorporated as botanical insecticides against mosquito vectors with high safety to non-target organisms.

Urinary Schistosomiasis around Oyan Reservoir, Nigeria: Twenty Years after the First Outbreak

BACKGROUND

Oyan reservoir, South-West Nigeria was constructed in 1984 to generate electricity but has altered the existing physical, biological and socio-economic environment of the people. This study, carried out between October 2006 and March 2008, aimed at investigating the current status of Schistosoma haematobium infection around the reservoir.

METHODS

Urine samples from 536 participants in five communities were examined for haematuria using reagent strips and S. haematobium ova was detected using sedimentation by gravity method. The participants were drawn from Abule Tuntun (n= 115), Ibaro (n= 156), Imala Odo (n= 88), Imala (n= 103) and Apojula (n= 74) communitie.

RESULTS

Prevalence rates by haematuria were (Abule Tuntun- 33.04%; Ibaro- 73.07%; Imala odo- 60.22%; Imala- 7.77%; Apojula - 39.19%) and by presence of parasite ova were (Abule Tuntun- 39.13%; Ibaro- 83.97%; Imala Odo- 62.5%; Imala- 20.39%; Apojula- 54.05%).

CONCLUSION

S. haematobium transmission has been sustained in the reservoir since the outbreak was first reported in 1988. Mass treatment with praziquantel was conducted 8 years ago (2001) in two of the communities. However, the infection has persisted due to lack of pipe borne water and safe waste disposal system.

Population dynamics of indoor sampled mosquitoes and their implication in disease transmission in Abeokuta, south-western Nigeria

BACKGROUND & OBJECTIVES

A longitudinal study was carried out to investigate the species composition, seasonal abundance, parity and feeding preference of indoor sampled mosquitoes in Abeokuta, south-western Nigeria.

METHODS

The mosquitoes were sampled weekly from five stratified locations using Center for Disease Control (CDC) light-traps between August 2005 and July 2006. The mosquitoes were examined for abdominal condition and dissected for age composition. Microscopic and precipitin techniques were also employed for the determination of host blood source.

RESULTS

A total of 2969 mosquitoes which belong to 10 species of mosquitoes were collected during the study period. Mansonia africana (35.65%) constituted the most abundant species followed by Culex quinquefasciatus (32.23%) and Anopheles gambiae complex (13.52%). Other species in decreasing order of abundance were Coquilletidia maculipennis (8.2%), Aedes albopictus (5.9%), Ae. aegypti (1.93%), M. uniformis (1.81%), Cx. duttoni (0.25%), Cx. tigripes (0.25%) and An. funestus (0.25%). Seasonal abundance revealed a significant difference (p <0.05) in the population of mosquito vectors collected during the wet season as compared to the dry season and their abundance was positively correlated with rainfall. The results showed that the majority of the vector species collected were unfed and nulliparous. Moreover, the blood meal test was positive for human blood.

CONCLUSION

The preponderance of mosquitoes observed in the study is of public health concern since they serve as vectors of most tropical diseases including malaria.

Mosquito larval habitats and public health implications in Abeokuta, Ogun State, Nigeria

The larval habitats of mosquitoes were investigated in Abeokuta, Nigeria in order to determine the breeding sites of the existing mosquito fauna and its possible public health implications on the residents of the City. The habitats were sampled between August 2005 and July 2006 using plastic dippers and a pipette. The habitats were grouped as ground pools/ponds, gutters/open drains, tyres, domestic containers and treeholes/ leaf axils. Ten species of mosquitoes were encountered in the five habitats namely Mansonia africana, M. uniformis, Culex quinquefasciatus, Aedes aegypti, Ae. albopictus, Ae. vittatus, Cx tigripes, Anopheles gambiae s.l., An. funestus and Eretmapodite clnysogaster. Ae. aegypti bred in all the habitats sampled while Cx quinquefasciatus bred in four habitats except tree holes/leaf axils. An. gambiae s.l and Ae. albopictus occurred in three habitats while other species bred only in one or two habitats. Ground pools and domestic containers recorded the highest number of species followed by gutters/open drains. Tree holes/leaf axils was the least preferred habitat with the lowest number of species occurrence. However, statistical analysis revealed non-significant difference in species occurrence in the five habitats. The availability of the habitats to support the breeding of Aedes, Culex and Anopheles, which are known vectors of urban yellow fever, lymphatic filariasis and malaria suggest that the residents ofAbeokuta City are at risk of mosquito-borne diseases. It is important that residents of the City are enlighten on the environmental factors that contribute to mosquito breeding and that the Government should institute proper sanitation measures to reduce mosquito breeding sites.

Morphometric studies on Culex quinquefasciatus and Mansonia africana (Diptera: Culicidae) in Abeokuta, south-western Nigeria

Some of the important mosquito species are generally sympatric in terms of their geographical distributions, and are difficult to identify based solely on examination of adult females using the available morphological keys. In this study, adult mosquitoes were collected indoors in Abeokuta in south-western Nigeria between August 2005 and July 2006 using Center for Disease Control light traps. The objective was to investigate possible morphological differences in populations of Culex quinquefasciatus and Mansonia africana. Six morphological characters namely, wing length, antennal length, proboscis length, foreleg length, mid leg length and hind leg length were measured in the two species. A total of 868 Cx quinquefasciatus and 962 M. africana were collected during the study period. The mean length was observed to be higher in most characters during the wet season than the dry season but the variation was not statistically significant (P > 0.005). In M. africana, the antennal length, proboscis length, foreleg length and midleg length showed one peak each. The wing length exhibited three peaks while hind leg length showed two peaks. For Cx quinquefasciatus, the antennal length, proboscis length, foreleg length, mid leg length and hind leg length indicated one peak. The wing length however showed three peaks. Each of the peaks observed in wing length and hind leg length of M. africana and wing length of Cx quinquefasciatus was assumed to be a specific population. The coefficient of differences (CDs) for each population indicated the presence of three populations in M. africana (CD > 1.28). However, the hind leg length showed that the two populations were the same (CD < 1.28). Three populations were also obtained from CD for wing leg length of Cx quinquefasciatus (CD > 1.28). Other characters indicated the presence of only one population. The results therefore underscore the need to investigate the status of the two species in relation to species complex.