Concurrence of dermatological and ophthalmological morbidity in onchocerciasis.

Prevalence of skin and eye disorders in African onchocerciasis (river blindness) is well documented. However, less is known about their joint occurrence. Information on concurrence may improve our understanding of disease pathogenesis and is required to estimate the disease burden of onchocerciasis. We analysed data from 765 individuals from forest villages in the Kumba and Ngambe Health districts, Cameroon. These data were collected in 1998, as baseline data for the evaluation of the African Programme for Onchocerciasis Control. Concurrence of symptoms was assessed using logistic regression. Onchocerciasis was highly endemic in the study population (63% nodule prevalence among males aged ≥20). Considerable overall prevalences of onchocercal visual impairment (low vision or blindness: 4%), troublesome itch (15%), reactive skin disease (19%), and skin depigmentation (25%) were observed. The association between onchocercal visual impairment and skin depigmentation (OR 9.0, 95% CI 3.9-20.8) was partly explained by age and exposure to infection (OR 3.0, 95% CI 1.2-7.7). The association between troublesome itch and reactive skin disease was hardly affected by adjustment (adjusted OR 6.9, 95% CI 4.2-11.1). Concluding, there is significant concurrence of morbidities within onchocerciasis. Our results suggest a possible role of host characteristics in the pathogenesis of depigmentation and visual impairment. Further, we propose a method to deal with concurrence when estimating the burden of disease.

[Onchocerciasis in the area of Lastourville, Gabon. Clinical and entomological aspects]. / L'onchocercose dans la région de Lastourville, Gabon. Aspects cliniques et entomologiques.

The African Programme for Onchocerciasis Control (APOC) has implemented a series of surveys aimed at evaluating the long-term impact of its activities. The region of Lastourville (Gabon) is one of the selected sites for this study. A total of 886 persons was examined for skin lesions, and 459 out of them participated in detailed ocular examinations. Blackflies were collected during one year and dissected. Although the focus was found to be hypoendemic (prevalence of nodules: 7.7%), the frequency of onchodermatitis was relatively high. The lesions of the anterior segment of the eye were rare, but the prevalence of optic nerve disease, and of choroido-retinal lesions reached 5.2 and 2.7%, respectively. The annual transmission potential (2,171 infective larvae per man) was high, when compared with the results recorded in the human population. This may be due to the presence of Onchocerca spp. of animal origin in the blackflies. These results indicate that in the area of Lastourville, though regarded as the main focus of onchocerciasis in Gabon, the disease is relatively mild.

[African Programme for Onchocerdasis Control (APOC): Onchocerca Simulium squamosum in two regions in the Republic of Cameroon]. / Programme africain de lutte contre l'onchocercose (APOC): intensité de la transmission d'Onchocerca volvulus par Simulium squamosum dans deux régions de la République du Cameroun.

In 1998, the African Programme for Onchocerciasis Control (APOC) decided to launch a long-term impact assessment of its operations. This paper reports the baseline entomological data collected throughout a whole year in two sites of Cameroon (Kahn and Bolo). The Simulium populations of the two study sites were characterized by parous rates of 7.2% and 33.5% respectively and infectivity by O. volvulus of 31 and 190 infective larvae per 1000 parous flies respectively The Annual Transmission Potentials (ATP) were respectively 523 and 9972 infective larvae per man and per year in Kahn and in Bolo. The Simulium populations studied in both sites, even though the ATP in Kahn is 19 times lower than that of Bolo, showed a pattern of an onchocerciasis hyperendemic zone in terms of vector capacities and entomological indices.

[African Program for Onchocerciasis Control (APOC): Onchocerca volvulus transmission by Simulium damnosum s. l. in two regions of the Central African Republic]. / Programme africain de lutte contre l'onchocercose (APOC): transmission d'Onchocerca volvulus par Simulium damnosum s. l. dans deux régions de la République Centrafricaine.

Entomological baseline data were collected in the villages of Zinga and Boali-Falls in Central African Republic (CAR) in view of the long term impact assessment of community-directed treatment with ivermectin (CDTI). Morphological determinations revealed that flies caught in both sites belong to the sub-group Sou/Sq. In Boali, the nuisance was relatively high with biting rates averaging 243 bites/man/day, with a parous rate of 61.6% and a crude annual transmission potential (ATP) of 8,259 infective larvae/man/year; and the average number of infective larvae per 1,000 parous flies was 177. In Zinga, the mean biting rate was 191 bites/man/day, with a parous rate of 51.6%, a crude ATP of 3,422, and 86 infective larvae per 1,000 porous flies. In conclusion, the vectorial capacity and the entomological indices recorded are characteristic of high onchocerciasis transmission zones. However, some of the infective larvae found, maybe of animal origin, need identification to better determine the real level of endemicity.

[Retinal hemorrhages after ivermectin treatment for onchocerciasis in a patient with Loa loa microfilaremia]. / Survenue d'hémorragies rétiniennes lors du traitement de l'onchocercose par l'ivermectine chez une patiente co-infectée par la loase.

A case of retinal hemorrhages with special features and degradation of the general condition is reported in a 27-year-old female patient, following the ingestion of ivermectin for the treatment of onchocerciasis. The patient was infested by both Onchocerca volvulus and Loa loa. A bilateral peripheral temporal location of the retinal lesions was observed. The role of L. loa microfilarial load in the occurrence of the retinal lesions as well as the transient character of the lesions are discussed, based on the clinical observation and with reference to the literature. The authors call for setting up a rapid therapeutic system to take care of serious adverse reactions following treatment with ivermectin in areas with a high prevalence of L. loa infestation.

Ocular findings after ivermectin treatment of patients with high Loa loa microfilaremia.

Hemorrhages in the palpebral conjunctiva (HPCs) have been recorded in patients living in an area endemic for loiasis who developed serious reactions after ivermectin treatment. A study was designed to evaluate the frequency of these lesions, and to identify risk factors associated with their appearance. The conjunctivae of 1,682 patients who complained of reactions were systematically examined. HPCs were found in 41 patients. The initial mean Loa loa microfilaremia in the individuals with HPCs was 14,900 microfilariae (mf) per mL, as compared with 14.5 mf/mL in the other patients. Mansonella perstans microfilaremia and male gender were also associated with HPCs. Post-treatment fundus examinations were performed on 37 patients, and a close relationship was found between the occurrence of HPCs and the presence of retinal lesions. The vascular pathological processes leading to the ocular lesions may be similar to those which occur at the cerebral level in patients harboring high L. loa microfilaremia who develop neurologic troubles after ivermectin treatment. Retinal lesions may represent a special feature of the Loa-related encephalopathies useful for differential diagnosis, and the HPCs may be useful as an alarm sign to identify those individuals who might develop serious reactions after ivermectin treatment.

Effect of repeated ivermectin treatments on ocular onchocerciasis: evaluation after six to eight doses.

In 26 villages (1987 population 12,302), hyperendemic for savanna onchocerciasis in North Cameroon, ivermectin was distributed annually between 1987/89 and 1995. Each year until 1992, ophthalmologic examinations were performed before treatment. A final examination was made in 1995. The effects of ivermectin on ocular onchocerciasis were assessed by following (a) the ophthalmologic indices in three cohorts of males recruited before treatment in 1987, 1988 and 1989, who were treated and examined annually, and (b) the indices recorded yearly in the cross-section of males aged 15-19 years. The indices in 1995 from patients who had received up to eight doses were compared with those calculated before treatment in individuals of similar age. In the cohorts, the prevalences of microfilariae in the anterior chamber (MFAC) and of punctate keratitis (PK) recorded in 1995 were markedly reduced; there was a non-significant decrease in sclerosing keratitis (SK), and a significant worsening in the fundus indices in the cohorts. The cross-sectional analysis showed significant decreases in the prevalences of MFAC, PK and SK, and a significant increase in the mean visual acuity; there was no significant change in any fundus index. The findings suggest that repeated ivermectin treatment does not prevent the appearance of initial retinal lesions or the worsening of existing retinal lesions.

A population-based study of xerophthalmia in the extreme North Province of Cameroon, West Africa.

OBJECTIVE: To obtain cross-sectional data on clinical and nutritional vitamin A deficiency from which to design appropriate intervention strategies. DESIGN: A population-based survey using multistage, cluster sampling. SETTING: Extreme North Province of Cameroon, West Africa. PARTICIPANTS: Children aged 0 to 5 years. MAIN OUTCOME MEASURES: Clinical signs of active xerophthalmia and dietary vitamin A intake. RESULTS: Of 5352 children examined, signs of active xerophthalmia were noted in 0.62%. Bitot's spots, corneal xerosis, and corneal ulceration were noted in 0.47%, 0.06%, and 0.12% of the subjects, respectively. Children with xerophthalmia had lower vitamin A intake scores when compared with age-matched controls and with a 20% systematic subsample of children. CONCLUSION: Xerophthalmia is a major public health problem in this region.

Prevalence and causes of low vision and blindness in the Extreme North Province of Cameroon, West Africa.

A survey to determine the prevalence and causes of blindness and visual impairment in the Extreme North Province of Cameroon was conducted in the Spring of 1992. A total of 10,647 people age 6 years and older was selected from a multi-stage, clustered sample stratified by ecological zone. The subjects were examined by ophthalmologist-led teams for visual acuity and ocular diseases. Approximately 1.2% of the sample was bilaterally blind by the World Health Organization classification (Category 3) of vision less than the ability to count fingers at 3 meters. Similarly to results found in other developing countries, senile cataract was the most common diagnosis encountered and the most frequent principal cause of low vision and blindness.

A study of onchocerciasis with severe skin and eye lesions in a hyperendemic zone in the forest of southwestern Cameroon: clinical, parasitologic, and entomologic findings.

Prior to the initiation of an onchocerciasis control program based on the mass administration of ivermectin in the rain forest of southwestern Cameroon, a preliminary baseline study of the area was conducted. The results of this study showed that onchocerciasis was hyperendemic in the area. Skin symptoms and signs were observed including pruritus (67.4% of the population examined), onchocerca nodules (51.6%), skin depigmentation (18.5%), and hanging groins (5.7%). Except for pruritus, the prevalence of these symptoms increased with age. Of the eyes examined, 44.9% had microfilariae in the anterior chamber, 33.5% had choroidoretinitis, 28.0% had punctate keratitis, 8.3% had papillary abnormalities, and 3.6% had sclerosing keratitis. Vision in 10.5% of the eyes examined was classified as blind or very poor (visual acuity = 0-0.10), in 15.7% as poor (visual acuity = 0.11-0.39), and in 73.8% as good (visual acuity = 0.4-1.00). Unlike previous reports that have linked serious ocular damage mainly to savanna onchocerciasis, the present study showed that forest onchocerciasis also caused significant ocular pathology, including blindness. Parasitologically, positive skin snips were recorded for 92.7% of the persons examined, with both sexes being equally infected. The parasite load, expressed as the geometric mean number of microfilariae per skin snip, was 53.6, and was much higher in males than in females. The flv vector, Simulium squamosum, had a high infection rate of 7.5% infective females in Bakumba and 6.8% infective females in Ngbandi, the two fly-catching points. The transmission potential was 266 infective larvae per person per month in Bakumba and 189 in Ngbandi.

A community-based trial of ivermectin for onchocerciasis control in the forest of southwestern Cameroon: clinical and parasitologic findings after three treatments.

In the onchocerciasis-endemic rain forest area of the Rumpi Hills in southwestern Cameroon, a community-based trial of ivermectin, given either once or twice a year over a three-year period (1988-1991), confirmed that the drug is a potent microfilaricide. The side effects recorded following the first treatment were edema, fever, pruritus, generalized body pains and lymphadenitis. Following subsequent treatments, the same adverse reactions were recorded, but these were generally milder when compared with those of the first treatment. The prevalence of skin microfilaria (mf) was more reduced in zone two, in which treatment was given every six months (76.9% reduction at the end of one year) than in the zone one, in which treatment was given once a year (7.4% reduction). In both zones, the impact of the drug in reducing the intensity of infection was more significant than that for prevalence. Besides pruritus, other skin symptoms were not significantly modified by ivermectin treatment. Ivermectin reduced the prevalence of ocular mf as well as the mf load of the anterior chamber of the eye, resulting in improvement of certain eye lesions such as punctate keratitis, anterior uveitis, and papillary anomalies. There was also some improvement in visual acuity. The level of participation of the village populations was somewhat low, ranging from 52% to 66%, despite excitement over the drug's additional benefit of expelling intestinal round worms.

[Control of onchocerciasis with ivermectin: results of a mass campaign in northern Cameroon]. / Lutte contre l'onchocercose par ivermectine: résultats d'une campagne de masse au Nord-Cameroun.

A mass chemotherapy campaign to treat onchocerciasis with ivermectin was carried out in northern Cameroon, in the North Vina valley, a savanna area that is part of the extended Vina-Pendé-Longone focus. More than 20,000 people aged five years and over were treated at least once and more than 30,000 treatments were distributed. One to four treatments were given at intervals of six months or one year. Clinical and parasitological examinations of representative samples of the treated population and full ophthalmological examinations of males aged 15 to 35 years were carried out before each treatment to assess the efficacy of the different protocols of treatment. Secondary effects were recorded daily during the week after administration of ivermectin in the whole population treated. The evolution of arterial blood pressure was monitored over seven days in about 300 adults living in the hyperendemic region. The impact of mass treatment on natural transmission of the disease was evaluated by daily capture and dissection of blackflies during the month before and the two months after treatment. All levels of onchocerciasis endemicity were represented in the study area (maximum community microfilarial load (CMFL), 300 microfilariae per biopsy). Six months and one year after the first treatment, loads were down by more than 90% and more than 60% respectively.(ABSTRACT TRUNCATED AT 250 WORDS)