Long-term suppression of Mansonella streptocerca microfilariae after treatment with ivermectin. (1/29)

The long-term effect of a single oral dose of 150 microg/kg of body weight of ivermectin on Mansonella streptocerca microfilariae was studied in western Uganda. Before treatment, the geometric mean microfilaria density (mf) in 93 infected persons was 2.4 mf/mg of skin (range, 0.1-42.6). One year after treatment, 43 persons (46%) were microfilaria-negative, and the geometric mean in the remaining persons dropped significantly, to 0.7 mf/mg (range, 0.1-6.9). Thus, ivermectin is highly effective against M. streptocerca, and a single dose leads to a sustained suppression of microfilariae in skin. In Africa, ivermectin is used for mass treatment to control Onchocerca volvulus and Wuchereria bancrofti. Because these filarial parasites are often coendemic with M. streptocerca, the treated population may receive the additional benefit of suppression of M. streptocerca microfilariae.  (+info)

Mansonella ozzardi infection in Bolivia: prevalence and clinical associations in the Chaco region. (2/29)

A cross-sectional survey carried out in the Chaco region of Bolivia showed that 26% (77 of 296) and 0.7% (2 of 298) of the rural population of the Camiri and Villa Montes areas, respectively, harbored Mansonella ozzardi microfilariae (mf). No significant differences were observed between sexes. The lowest prevalence (9%) was in the 0-14-year-old age group, with no children <11 months of age infected. The prevalence increased sharply in the 25-34-year-old age group (32%), and continued increasing in the older age classes. Microfilaremia, ranging from 1 to 305 mf/20 microl of blood, was lowest in 0-14-year-old children (geometric mean concentration = 1.1 mf/20 microl), and increased with age (>100 mf/20 microl in people >44 years old). An expected increasing sensitivity with the blood volume examined was observed. No significant association between clinical symptoms (fever, skin rash, pruritus, headache, lymphedema, elephantiasis, and articular pain) and microfilaremia was observed.  (+info)

Use of the recombinant Onchocerca volvulus protein Ov20/OvS1 for the immunodiagnostic differentiation between onchocerciasis and mansonelliasis and for the characterization of hyperreactive onchocerciasis (sowda). (3/29)

The protein Ov20/OvS1 was used as antigen in ELISA and Western blot in order to differentiate onchocerciasis from African mansonelliasis and to characterize the hyperreactive form of Onchocerca volvulus infection (sowda). The specificity of the IgG4 Western blot was 98% for the differentiation between persons with onchocerciasis and Mansonella microfilariae (mf) carriers (125 persons with M. perstans and 92 with M. streptocerca), whereas the IgG4 ELISA showed a specificity of 81% in 137 M. perstans mf carriers and 85% in 94 M. streptocerca mf carriers. The sensitivity of Ov20/OvS1 in identifying onchocerciasis using the IgG4 ELISA was 75% for 103 O. volvulus mf carriers with the generalized and 89% for 44 patients with the sowda form of onchocerciasis. IgE antibodies against OvS1 were found in 95% of 39 patients with hyperreactive onchocerciasis but only in 15% of 47 persons with the generalized form. Thus, Ov20/-OvS1 appears a promising candidate antigen for the diagnosis of onchocerciasis and in particular for the detection of the sowda type of disease.  (+info)

Simuliid blackflies (Diptera: Simuliidae) and ceratopogonid midges (Diptera: Ceratopogonidae) as vectors of Mansonella ozzardi (Nematoda: Onchocercidae) in northern Argentina. (4/29)

Mansonella ozzardi, a relatively nonpathogenic filarial parasite of man in Latin America, is transmitted by either ceratopogonid midges or simuliid blackflies. In the only known focus of the disease in north-western Argentina the vectors have never been incriminated. This study investigated the potential vectors of M. ozzardi in this area. The only anthropophilic species of these Diptera families biting man at the time of the investigation were Simulium exiguum, S. dinellii, Culicoides lahillei and C. paraensis. Using experimentally infected flies S. exiguum and both species of Culicoides allowed full development of microfilariae to the infective stage, with C. lahillei being a more competent host than S. exiguum. Based on these data, biting rates and natural infectivity rates it is probable that at the begininning of the wet season C. lahillei is the main vector of M. ozzardi and both C. paraensis and S. exiguum secondary vectors. Additionally, it was found that a single dose of ivermectin was ineffectual in eradicating M. ozzardi from infected individuals in this area.  (+info)

Helminth infection is not associated with faster progression of HIV disease in coinfected adults in Uganda. (5/29)

BACKGROUND: We studied a cohort of human immunodeficiency virus (HIV)-infected adults in Uganda who were not receiving antiretroviral therapy, to explore the impact of helminths on HIV progression in areas where antiretrovirals are not available. METHODS: A total of 663 patients were screened for helminths, treated presumptively with albendazole and selectively with praziquantel, and monitored for 6 months. Blood samples were analyzed for CD4+ cell count and HIV-1 RNA. RESULTS: Schistosoma mansoni, hookworm, Strongyloides stercoralis, and Mansonella perstans were the most prevalent helminths. Helminth infection was not associated with higher viral load, lower CD4+ cell count, or faster decrease in CD4+ cell count preceding antihelminthic therapy. The effect of coinfection on HIV disease progression varied with species. CD4+ cell counts were highest in subjects with hookworm and Mansonella perstans infection. For most helminths, effective treatment was associated with greater decrease in CD4+ cell count than in those in whom infection was still present at follow-up. A highly significant decrease in viral load at 6 months was seen in patients with persistent Mansonella perstans infection at follow-up. Mortality was lower in subjects with hookworm infection at enrollment. CONCLUSION: Helminth infection was not associated with more-advanced HIV disease or faster disease progression. Antihelminthic therapy may not be beneficial in slowing HIV progression in coinfected adults.  (+info)

Prevalence of Mansonella perstans infections among the nomadic Fulanis of northern Nigeria. (6/29)

The study was undertaken to investigate the prevalence and clinical manifestations of Mansonella perstans infection in the nomadic Fulanis of northern Nigeria. Physical examination of 755 consenting nomads for clinical manifestations of M. perstans infection was carried out between June 1996-September 2000. This was followed by parasitological examination of blood samples collected by finger prick method to identify microfilariae (mf). Data collected was stratified by locality, age and sex, and analyzed using the Chi-square test. Overall, 66 (8.7 %) of 755 nomads were infected. Infection was higher in men (9.7 %) than in women (6.5 %) (p<0.05) and occurred in all age groups with highest prevalence in persons in the 4th (14.1 %) and 5th (17.1 %) decades of life. Fifty-six (81.8 %) of the 66 nomads with mf had clinical manifestations with periodic dizziness (18.2 %), body itching (15.2 %) was the most prevalent while back pain (7.6 %) was the least. The findings show that mansonelliasis is an important health problem in nomads. This underscores the need to establish a well-articulated Filariasis Control Programme for this group whose major health problems are rooted in their occupation and amplified by several contingencies of the environment.  (+info)

Short communication: impact of long-term (14 years) bi-annual ivermectin treatment on Wuchereria bancrofti microfilaraemia. (7/29)

Ivermectin has been and continues to be extensively used to control onchocerciasis in areas of hyper and mesoendemicity within the African Programme of Onchocerciasis Control. As programmes to eliminate lymphatic filariasis (LF) caused by Wuchereria bancrofti expand, areas of coendemicity with onchocerciasis will be incorporated into LF programmes. This study reports that in villages which were hyperendemic for onchocerciasis after some 14 years of treatment with ivermectin, no W. bancrofti could be detected in a population of 1210 individuals whilst in adjacent villages a prevalence of around 3% was found. Despite the long period of ivermectin treatment Mansonella perstans did not appear to respond to ivermectin in this setting.  (+info)

Biting of anthropophilic Culicoides fulvithorax (Diptera: Ceratopogonidae), a vector of Mansonella perstans in Nigeria. (8/29)

Anthropophilic Culicoides were investigated in a rural community endemic for Mansonella perstans in Ijebu North area of western Nigeria between December 2003 and October 2004. Three hundred and fifty-nine adults of Culicoides fulvithorax collected by human bait in the morning were dissected for Mansonella perstans larvae, and 1.95% of infection rate was found. Seasonal abundance of C. fulvithorax was investigated by monthly biting rates, and showed that higher prevalence was observed in rainy season, with peak in September. Culicoides prevalence was positively correlated with rainfall and relative humidity, but not temperature. Human perceptions on the behavior of these biting midges were determined by interviewing 854 self-selected villagers, of which 86.5% of the interviewees confessed having experienced Culicoides bites. Between 76.5 and 99.1% of the various age groups complained body reactions to Culicoides bites. Itching was the most frequent body reaction. No interviewees associated Culicoides with transmission of any parasitic infections. The results showed need to adequately control Culicoides in the community.  (+info)