Morphological and ultrastructural changes in small blood vessels of rabbits infected with Trypanosoma brucei

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Comparing antibody responses to Onchocerca volvulus and non-parasite antigens in placebo-controlled and ivermectin-treated onchocerciasis patients

Serum antibodies to parasite-specific and non-parasite antigens were evaluated  using enzyme-linked immunosorbent assay (ELISA). Out of the 470 sera collected, 409 were from residents of an onchocerciasis hyper-endemic area, 55 non-endemic and 6 European normal sera served as control. The patients’ age, sex, skin  microfilaria densities, dermal and ocular clinical manifestations (colour of optic disc) have been well characterised. The study population had participated in a  placebocontrolled (n=191) trial of ivermectin (Mectizan®) treatment (n=218). The parasite antigens are phosphate buffered saline crude extract of adult worms of Onchocerca volvulus, a recombinant antigen (Ov1.9) and a monoclonal antibody purified antigen (Cam 1). The non-parasite antigens are deoxycholate citrate extract of optic nerve (nerve-DOC) and commercially available IgA, IgM and IgG were used to assay for rheumatoid factor (Rh-F) auto-antibodies. Generally, antibodies to parasite antigens in onchocerciasis patients were remarkably higher than control group (p<0.05) using exact F-test. There was no significant difference (p>0.05) in antibodies to nerve-DOC and Rh-F in patients compared to control. Antibodies increased with increasing skin snip microfilaria load from 0.69±0.28 with 0mf/mg (n=54) as against 0.80±0.26 for those with 4-20mf/mg. Observed slight negative correlation in IgG antibody levels and severity of disc colour with mean OD values of 0.26±0.22 in those graded as having no optic nerve disease (OND) (disc 1, n=86) and 0.17±0.19 for those with severe changes (disc 3, n=49) was not statistically significant (P>0.05). An age dependent significant decrease (P<0.05) in antibodies were observed with 0.64±0.34 for 15-30yr old (n=48) compared to 0.48±0.35 for those 50yr (n=50) for PBS with a similar trend for IgG to Ov1.9 and Cam1. In conclusion, serum parasite-specific and non-parasite antibodies may not be responsible for the pathology of optic nerve disease. Onchocerciasis patients were apparently not at higher risk of developing rheumatoid arthritis than the control.Keywords: Onchocerciasis; Antibodies; Antigens; Immune responses; Ivermectin

Civil conflict and sleeping sickness in Africa in general and Uganda in particular

Conflict and war have long been recognized as determinants of infectious disease risk. Re-emergence of epidemic sleeping sickness in sub-Saharan Africa since the 1970s has coincided with extensive civil conflict in affected regions. Sleeping sickness incidence has placed increasing pressure on the health resources of countries already burdened by malaria, HIV/AIDS, and tuberculosis. In areas of Sudan, the Democratic Republic of the Congo, and Angola, sleeping sickness occurs in epidemic proportions, and is the first or second greatest cause of mortality in some areas, ahead of HIV/AIDS. In Uganda, there is evidence of increasing spread and establishment of new foci in central districts. Conflict is an important determinant of sleeping sickness outbreaks, and has contributed to disease resurgence. This paper presents a review and characterization of the processes by which conflict has contributed to the occurrence of sleeping sickness in Africa. Conflict contributes to disease risk by affecting the transmission potential of sleeping sickness via economic impacts, degradation of health systems and services, internal displacement of populations, regional insecurity, and reduced access for humanitarian support. Particular focus is given to the case of sleeping sickness in south-eastern Uganda, where incidence increase is expected to continue. Disease intervention is constrained in regions with high insecurity; in these areas, political stabilization, localized deployment of health resources, increased administrative integration and national capacity are required to mitigate incidence. Conflict-related variables should be explicitly integrated into risk mapping and prioritization of targeted sleeping sickness research and mitigation initiatives

Anaemia in Yankassa Rams Infected with Trypanosoma Congolense, T. Vivax and T. Brucei and their Erythrocytic Responses

One of the most consistent features of trypanosomiasis in any parasite host. The main objective of this study was to therefore evaluate the bone marrow responses to anaemia, generated in Yankassa rams infected with three most common trypanosomes species (T. congolense, T. vivax and T. brucei), affecting Nigerian animals, both at acute and chronic phases.Three groups of Yankassa rams were infected with Trypanosoma congolense, T. vivax and T. brucei, respectively. Each infection group was subdivided into two. While a subgroup was not treated to allow the animals run an acute course, the other subgroup precipitated a chronic course with the application of subcurative doses of diaminazene aceturate. In acute infections, there was a rapid development of anaemia, with PCV dropping down to between 16 and 17%, high parasitaemia in all the subgroups of the three infections, and death, especially in untreated T. brucei subgroup within 5 to 6 weeks of infection. The rapidly developed anaemia in acutely infected animals showed no evidence of increased erythropoiesis in circulation as measured by the level of reticulocytosis in all the three trypanosomal infections. Chronic infections ran for 8-15, 14-20 and 13-20 weeks post treatment in T. congolense, T. vivax and T. brucei infections, respectively. With subsequent relapses after treatment, infected animals had more severe anaemia with the PCV as low as 12 to 13% before death. Increased reticulocytosis developed between 7th and 9th weeks of infections coinciding with periods of low parasitaemia which was earliest with T. brucei infection. This however did not cancel the anaemia developed. Consequently, the reticulocyte responses throughout the infection were suboptimal and could not restore the declining PCV to normal, but at best, just maintained the low levels.Keywords: Erythrocytic response, rams, Trypanosoma congolense acute course, reticulocytosisNigerian Journal of Parasitology, Vol. 32 [1] March 2011, pp.109-11

Onchocerca volvulus: Characterization of the clinical status of onchocerciasis patients using antibodies reactivity in enzyme-linked immunosorbent assays

Serum anti-bodies, IgA, IgG class and subclasses (excluding IgG2) and IgM responses to crude sodium-duodecyl sulphate (SDS) extract of Onchocerca volvulus female adult worms, were tested with indirect enzyme-linked immunosorbent assay (ELISA). Antigenic epitopes defined by monoclonal anti-bodies (mAbs) designated CAM8, CAM22 and CAM28 were measured using inhibition (competitive) ELISA. Generally, cases (n=95) with proven parasitological and or clinical evidences had the highest mean optical density (OD) values for IgG, IgG1, IgG3 and IgG4 anti-bodies compared to the endemic normal (n=19) and non-endemic control (n=7) groups. Reactivity varied with infection status and was more in those having skin microfilariae than those without skin mf. Individuals with chronic skin diseases (n-20) had higher anti-body levels than those with optic nerve disease (OND, n=12). Serum inhibition of Cam22 was higher, while Cam28 was lower in those with, than without skin microfilariae. Those manifesting chronic skin diseases showed a remarkable increase in percentage inhibition of both mAbs in sharp contrast to the OND group. There were very few Cam8 responders which did not show any apparent clinical trend. It is not known whether this is an indication of selective tolerance or immunosupression. The study showed that anti-body responses to the parasite antigens had strong positive association (