Onchocerciasis (river blindness): larva-induced eczema (onchodermatitis) from an important oculocutaneous tropical disease spilling over into North America and Europe.

Onchocerciasis is a leading cause of blindness in the world. It may be seen in temperate climates of the United States and Europe in immigrants and travelers from endemic regions, often linked to poverty and war. One should be aware of an incubation period that can be up to 15 months. In its early stage and throughout its course, onchocerciasis has noteworthy skin findings, facilitating diagnosis, as onchodermatitis resembles common eczema with variable degrees of papular, lichenoid, atrophic, and pigmentary alterations, features not suggestive if one is unaware of an individual's immigration and travel history. The same concept applies for the encysted worms (onchocercomas), as they tend to appear as common skin cysts and benign neoplasms. New methods can be employed to increase diagnostic sensitivity and specificity. Ivermectin is the gold standard of therapy, the use of which has almost miraculously eliminated this disease from large areas of the earth. However, its effect remains isolated to microfilariae and can be devastating in those coinfected with Loa loa. Recently, the symbiotic relationship between adult worms and Wolbachia bacteria has been discovered and, with it, the possibility of adding doxycycline as a treatment option. We also discuss coinfection with HIV and other diseases.

Acquired disorders with depigmentation: A systematic approach to vitiliginoid conditions.

Acquired disorders with depigmentation are commonly encountered by dermatologists and present with a wide differential diagnosis. Vitiligo, the most common disorder of acquired depigmentation, is characterized by well-defined depigmented macules and patches. Other conditions, such as chemical leukoderma, can present with similar findings, and are often easily mistaken for vitiligo. Key clinical features can help differentiate between acquired disorders of depigmentation. The first article in this continuing medical education series focuses on conditions with a vitiligo-like phenotype. Early recognition and adequate treatment of these conditions is critical in providing appropriate prognostication and treatment.

Case report of an epidural cervical Onchocerca lupi infection in a 13-year-old boy.

A 13-year-old boy presented with fever and neck pain and stiffness, which was initially misdiagnosed as culture-negative meningitis. Magnetic resonance images of the brain and cervical spine demonstrated what appeared to be an intradural extramedullary mass at the C1-3 level, resulting in moderate cord compression, and a Chiari Type I malformation. The patient underwent a suboccipital craniectomy and a C1-3 laminectomy with intradural exploration for excisional biopsy and resection. The lesion containing the parasite was extradural, extending laterally through the C2-3 foramina. Inflammatory tissue secondary to Onchocerca lupi infection was identified, and treatment with steroids and doxycycline was initiated. At the 6-month follow-up, the patient remained asymptomatic, with MR images demonstrating a significant reduction in lesional size. However, 10 weeks postoperatively, the infection recurred, necessitating a second operation. The patient was treated with an additional course of doxycycline and is currently maintained on ivermectin therapy. This is the second reported case of cervical O. lupi infection in a human. In the authors' experience, oral doxycycline alone was insufficient in controlling the disease, and the addition of ivermectin therapy was necessary.

Lymphatic filariasis and onchocerciasis.

Lymphatic filariasis and onchocerciasis are parasitic helminth diseases that constitute a serious public health issue in tropical regions. The filarial nematodes that cause these diseases are transmitted by blood-feeding insects and produce chronic and long-term infection through suppression of host immunity. Disease pathogenesis is linked to host inflammation invoked by the death of the parasite, causing hydrocoele, lymphoedema, and elephantiasis in lymphatic filariasis, and skin disease and blindness in onchocerciasis. Most filarial species that infect people co-exist in mutualistic symbiosis with Wolbachia bacteria, which are essential for growth, development, and survival of their nematode hosts. These endosymbionts contribute to inflammatory disease pathogenesis and are a target for doxycycline therapy, which delivers macrofilaricidal activity, improves pathological outcomes, and is effective as monotherapy. Drugs to treat filariasis include diethylcarbamazine, ivermectin, and albendazole, which are used mostly in combination to reduce microfilariae in blood (lymphatic filariasis) and skin (onchocerciasis). Global programmes for control and elimination have been developed to provide sustained delivery of drugs to affected communities to interrupt transmission of disease and ultimately eliminate this burden on public health.

Could neurocysticercosis be the cause of "onchocerciasis-associated" epileptic seizures?

We conducted a nodule prevalence survey in four onchocerciasis sentinel communities in Moyo and two in Kanungu districts of Uganda. Seven (33.3%) out of 21 excised "onchocercomas" (nodules) in Moyo District and excised onchocercomas from four of six persons in Kanungu District turned out to be cysts of Taenia solium. We concluded that the prediction of nodule prevalence for noninvasive rapid epidemiologic assessment (REA) to target areas for mass chemotherapy with ivermectin in the African Program for Onchocerciasis Control (APOC) supported areas may have been influenced by other pathologies. T. solium infection may be the main cause of "onchocerciasis-associated epileptic seizures" in many onchocerciasis endemic communities that have been causally linked to onchocerciasis. Lastly, widespread neurocysticercosis may be a concern in mass treatment programs that provide praziquantel (for managing schistosomiasis) or albendazole (for managing intestinal worms or lymphatic filariasis) because these drugs may kill cerebral cysticerci, resulting in severe adverse events.

Obstructive, granulomatous tracheitis caused by Onchocerca sp. in a dog.

A 3-year-old spayed female dog was admitted with a history of episodes of dyspnoea and coughing. Severe tracheal stenosis was found on radiography. The dog died during an episode of refractory dyspnoea. Necropsy revealed an obstruction of the thoracic part of the trachea because of a chronic granulomatous inflammation protruding into the tracheal lumen. Histological examination revealed nematodes, which were identified as Onchocerca sp. according to their morphological characteristics. In contrast to the common ocular manifestation in dogs, obstructive tracheitis caused by Onchocerca infection has not been reported before.

Rapid assessment method for prevalence and intensity of Loa loa infection.

OBJECTIVE: To assess the validity of observations on eye worm and Calabar swellings for the rapid assessment of the prevalence and intensity of loiasis at the community level. METHOD: A total of 12895 individuals over the age of 15 years living in 102 communities in Cameroon and Nigeria took part in the study. A standardized questionnaire was administered to participants from whom finger-prick blood samples were collected and examined for Loa loa microfilariae. Rapid assessments of the prevalence and intensity of loiasis were made on the basis of a history of eye worm or Calabar swellings. FINDINGS: There was a strong correlation between the indices of the rapid assessment procedures and the parasitological indices of L. loa endemicity. The rapid assessment indices were effective in diagnosing high-risk communities (sensitivity 94-100%; specificity 66-92%). The highest sensitivity (100%) and specificity (92%) were obtained with a rapid assessment procedure based on a history of eye worm lasting 1-7 days together with confirmation by the guided recognition of a photograph of adult L. loa in the eye. CONCLUSION: Rapid assessment of the prevalence and intensity of loiasis at the community level can be achieved using a procedure based on the history of eye worm lasting 1-7 days together with confirmation by the guided recognition of a photograph of an adult L. loa in the eye.

[Onchocerciasis and epilepsy. Epidemiological survey in Mali]. / Onchocercose et épilepsie. Enquête épidémiologique au Mali.

A door-to-door survey was conducted in 18 villages in Mali with a total of 5,243 inhabitants classified according to the endemicity of onchocerciasis. Each epileptic was matched with two controls. The survey protocol included the following steps in cases and controls: census taking, socioeconomic data, screening for epilepsy, clinical examination, laboratory testing to detect parasites in stools and urine, and snip-test. The crude prevalence of epilepsy was 13.35 per 1,000 (n = 70). Epidemiological study provided a number of valuable demographic insights concerning age at onset, type of seizure activity during seizure and personal and family medical history. A transverse study showed that the prevalence of epilepsy was not significantly higher (p = 9.09) in zones of high endemicity of onchocerciasis (16.1 per 1000) than in zones of low endemicity (10.8 per 1000). Case-control findings showed evidence of onchocerciasis in 22.4 p. 100 of epileptics and 21.7 p. 100 of controls (odds ratio = 1.02 IC 95 p. 100: 0.4-2.19, not significant). Various risk factors including genetic factors and low socio-economic status could explain the trend toward a higher incidence of epilepsy as well as higher morbidity rates in zones of high endemicity of onchocerciasis.

Peripheral lymphadenopathy in Nigeria.

A review was carried out on the histopathological diagnosis of peripheral lymph node biopsies processed and reported within a period of 18 years (1979-1996) in the Department of Pathology of University of Ilorin Teaching Hospital, Ilorin, Nigeria. A total of 751 cases from 468 male and 283 female patients within the age range of 1 year to 80 years were reviewed. Non-neoplastic lesions made up 50.8% while neoplastic lesions constituted 49.2%. Tuberculosis was the commonest cause of peripheral lymphadenopathy (31.4%) followed by metastatic lesions (19.3%). As a group, the lymphomas constituted 28.2% and were made up of Hodgkin's disease 12.6%, non-Hodgkin's lymphoma including Burkitt's lymphoma 15.6% (with Burkitt's alone constituting 3.3%). Few other infectious diseases found included toxoplasmosis, histoplasmosis and onchocerciasis. Non-specific reactive and inflammatory changes (both acute and chronic) collectively formed 17.6%. The primary sites of lymph node metastases could not be determined in 36.6% of netastatic lesions while the breast was the origin in 13.8% and was the highest incidence of metastatis. The commonest lymph node group affected was the cervical (42.6%) followed by inguinal (24.1%).

[Important parasitic nephropathies: update from the recent literature]. / Néphropathies parasitaires importées: mise au point à partir de la littérature récente.

Renal involvement in parasitic infections are polymorphic. Plasmodium malariae often leads to membranoproliferative glomerulonephritis whereas acute tubular necrosis or post-infectious acute glomerulonephritis are observed with Plasmodium falciparum. Urogenital taxis of Schistosoma haematobium is responsible for frequency of chronic tubular and interstitial nephritis. Without specific treatment, the renal function progressively deteriorates and urological complications appear. Schistosoma mansoni mainly leads to mesangial and membranoproliferative glomerulonephritis. Membranoproliferative and membranous glomerulonephritis are reported with loasis. Onchocerca volvulus also leads to membranoproliferative glomerulonephritis and lipoid nephrosis. Renal involvement with Wuchereria bancrofti is rare. With leishmaniosis, it is often mild but more serious observations are described: acute glomerulonephritis, nephrotic syndrome or acute interstitial nephritis. Renal hydatic cysts are diagnosed in two or three per cent of cases. Surgery is the only treatment. Immunosuppressive or antimalarial treatments seem to be ineffective in the outcome of chronic glomerulonephritis.

Independent evaluation of onchocerciasis rapid assessment methods in Benue State, Nigeria.

OBJECTIVE: To evaluate the prevalence of palpable nodules or skin depigmentation as rapid indicators of onchocerciasis epidemicity in at-risk communities. METHOD: We examined data collected in Benue State on 11035 individuals in 32 villages to evaluate these rapid assessment methods. RESULTS: The prevalence of palpable nodules correlates more closely with microfilarial prevalence (r=0.68, P<0.001) and community microfilarial load (r=0.64, P<0.001) than the prevalences of skin depigmentation or other potential rapid indicators. The recommended cut-off value for palpable nodules of 20% or more in males aged >20 years had a sensitivity of 94% and specificity of 50% compared to a cut-off of 40% or more for microfilarial prevalence in all ages. This would mean that in these 32 villages 17 of 18 would have been correctly identified for treatment, and a further 7 at lesser risk would have been targeted for treatment. CONCLUSIONS: Skin snipping and parasitological examination can be replaced by the simpler method of palpating onchocercal nodules to identify communities at serious risk of onchocerciasis. This has important operational benefits for onchocerciasis control programmes.

Onchocerciasis and epilepsy: a matched case-control study in the Central African Republic.

The occurrence of epileptic seizures during onchocercal infestation has been suspected. Epidemiologic studies are necessary to confirm the relation between onchocerciasis and epilepsy. A matched case-control study was conducted in dispensaries of three northwestern towns of the Central African Republic. Each epileptic case was matched against two nonepileptic controls on the six criteria of sex, age (+/-5 years), residence, treatment with ivermectin, date of last ivermectin dose, and the number of ivermectin doses. Onchocerciasis was defined as at least one microfilaria observed in iliac crest skin snip biopsy. A total of 561 subjects (187 cases and 374 controls) were included in the study. Of the epileptics, 39.6% had onchocerciasis, as did 35.8% of the controls. The mean dermal microfilarial load was 26 microfilariae per mg of skin (standard deviation, 42) in the epileptics and 24 microfilariae per mg of skin (standard deviation, 48) in the controls. This matched case-control study found some relation (odds ratio = 1.21, 95% confidence interval 0.81-1.80), although it was nonstatistically significant.

PIP: Epileptic seizures are frequent in neurocysticercosis and may occur during cerebral malaria. Findings are reported from a matched case-control study conducted in March 1996 in the savannah woodland region of northwest Central African Republic to determine whether any relation exists between Onchocerca volvulus infestation and epilepsy. About 70% of the study region's inhabitants are infested with O. volvulus. Each epileptic case was matched against 2 nonepileptic controls on the criteria of sex, age, residence, treatment with ivermectin, date of last ivermectin dose, and the number of ivermectin doses. Onchocerciasis was defined as at least 1 microfilaria observed in iliac crest skin snip biopsy. 187 cases and 374 controls were included in the study. 39.6% of the epileptics and 35.8% of the controls had onchocerciasis. The mean dermal microfilarial load was 26 microfilariae per mg of skin in the epileptics and 24 microfilariae per mg of skin in the controls. The relation between O. volvulus infestation and epilepsy was statistically nonsignificant.

Epilepsy, retarded growth and onchocerciasis, in two areas of different endemicity of onchocerciasis in Burundi.

A high prevalence of epilepsy (up to 1.3%) was observed in an area hyperendemic for onchocerciasis in the province of Bururi, Burundi. Following this observation, epileptics and controls were examined in 2 communes (administrative units) with different endemicity for onchocerciasis. Altogether, onchocerciasis was more frequent in epileptics (81.8%) than in controls from the same households (68.3%; P < 0.05). This difference was more marked in the hyperendemic area. Other possible causes of epilepsy, including cysticercosis, were infrequent (18 possible cases among 110 epileptics). During this survey, 9 epileptics with growth retardation were seen. They showed most characteristics of Nakalanga syndrome, which was described from Uganda. All 9 such cases were suffering from onchocerciasis. These findings give more evidence of a possible association between onchocerciasis and epilepsy, and between onchocerciasis and Nakalanga syndrome.

Survey of blindness in rural communities of south-western Nigeria.

A population based survey of rural communities in the Akinlalu-Ashipa ward of Ife North Local Government in Osun State, Nigeria, was conducted to determine the prevalence and causes of blindness. 2921 inhabitants were screened by a random cluster sample technique, out of whom 27 were blind in both eyes. The overall prevalence rate of blindness (best corrected visual acuity less than 3/60 in the better eye) was found to be 0.9% (95% confidence interval 0.84-0.96%). The rate of blindness increased with age, especially from age 60. The major causes of blindness were cataract and its sequelae (48.1%), onchocerciasis (14.8%), primary open angle type glaucoma (11.1%), corneal scar/phthisis bulbi (7.4%) and optic atrophy (7.4%). About half of the blindness is potentially curable through cataract surgery, and a third preventable through health education, early diagnosis and prompt treatment.

The prevalence of epilepsy follows the distribution of onchocerciasis in a west Ugandan focus.

Epidemiological surveys indicate that the prevalence of epilepsy is higher in developing countries than in industrialized countries. Except for neurocystocercosis due to Taenia solium, little is known about possible underlying causes. This article reports the relationship between epilepsy and onchocerciasis in an Onchocerca volvulus endemic area in West Uganda. Individuals complaining of seizures were identified by means of a population census in 12 villages. Active epilepsy was confirmed in 61 of 4743 inhabitants (crude prevalence rate = 1.3%; age-standardized rate = 1.1%). Distribution of epilepsy in the study area was clustered, ranging from a prevalence of 0.2% to 3.4% in different villages. Age-specific prevalence was highest between 10 and 19 years, with a rate of 3.6% for the study are as a whole, and up to 10.0% in villages of high epilepsy prevalence. The prevalence of onchocerciasis in the 10-19-year-old age group was assessed by skin-snip biopsy and ranged from 15% to 85% in different villages. Epilepsy was significantly more frequent in the three villages with the highest levels of O. volvulus endemicity than in other villages (P < 0.0001). Serological testing for T. solium infection was positive in one and borderline in three of 53 epilepsy patients tested. The significant correlation between epilepsy and onchocerciasis did not change when these four patients were excluded from the analysis. These findings suggest a strong association between epilepsy and onchocerciasis in this area. This could have significant implications for the concept of morbidity due to O. volvulus.

Concurrent parasitic infections in onchocerciasis and the occurrence of adverse reactions after ivermectin treatment.

Ivermectin is a safe, effective, and relatively well-tolerated drug for the treatment of human onchocerciasis. However, due to side effects of the drug, large-scale ivermectin distribution without medical supervision is not recommended. The mechanisms involved in the pathogenesis of ivermectin-induced adverse reactions are not yet known. Since onchocerciasis patients are likely to have concurrent parasitic infections, we investigated whether side effects that occur after ivermectin treatment could be related to the presence of parasite eggs and cysts in stool samples prior to treatment. One hundred twenty-nine onchocerciasis patients were treated with a single dose of ivermectin (150 micrograms/kg) and side effects were graded according to the classification of Greene and others. Stool samples were collected before and three days after treatment. A high percentage (80.5%) of the patients reported adverse effects (57% mild, 14.1% moderate, and 9.4% severe reactions). Most (95.1%) of the patients had one or more concurrent parasitic infections. No relationship could be found between the occurrence and extent of side effects and the severity of concurrent intestinal parasitic infections. However, side effects were significantly correlated with pretreatment microfilarial counts. Ivermectin treatment did not induce significant short-term changes in Trichuris trichiura or Schistosoma mansoni egg counts. However, a significant reduction in Ascaris lumbricoides egg counts and Entamoeba coli cyst loads was observed; a cure rate of 46% for cysts was reached. In contrast, hookworm egg production increased after ivermectin treatment. Further studies are required to verify ivermectin-induced changes in cyst and hookworm loads as well as the significance of these findings.

Prevalence of depigmentation of the shins: a simple and cheap way to screen for severe endemic onchocerciasis in Africa.

The prevalence of skin depigmentation in the pretibial region is closely correlated in the adult Congolese population with conventional indices (microfilarial index, mean microfilarial density, cyst index) for the evaluation of endemic onchocerciasis. Individuals over 15 years of age in endemic villages who had a microfilarial index of 80-90%, had a cystic index of 60-70% and a pretibial depigmentation index about 20% (30-40% for individuals aged > 50 years). Thus, in Africa, this new evaluation index offers a simple, noninvasive, quick and cheap way to identify areas where the level of endemic onchocerciasis is probably high and which are likely to benefit from an anti-onchocerciasis campaign.

PIP: Skin depigmentation is a classic diagnostic sign of onchocerciasis and presents typically as an irregular, flat spot surrounded by slightly hyperpigmented zones. The depigmentation occurs mainly on the shins. The prevalence of skin depigmentation has been proposed as a marker for evaluating the endemicity of onchocerciasis in Nigeria, but has been contested for use in South America on the grounds of non-specificity. The microfilarial index currently used to assess the level of onchocerciasis endemicity is relatively time-consuming, costly, and harbors the risk of transmitting viral infections during mass screenings. 991 people over 15 years of age of mean age 55.4 years in five villages in the Congo endemic for onchocerciasis participated in this study. Individuals who had a microfilarial index of 80-90% had a cystic index of 60-70% and a pretibial depigmentation index of approximately 20%. The authors conclude that the existence of shin depigmentation as an evaluation index in Africa offers a simple, noninvasive, quick, and inexpensive way to identify areas where the level of endemic onchocerciasis is probably high and which are likely to benefit from an anti-onchocerciasis campaign. Although the new index does not allow total specificity, the incidence of shin depigmentation among patients with African onchocerciasis is such that there is probably little risk of confusing holo- or hyperendemic zones with an area where leprosy or treponema are endemic. In the absence of onchocerciasis, bites from Simulium spp. flies may also be responsible for skin depigmentation, as may be streptocerciasis. In this latter condition, however, the predominant site of depigmentation is not the shin. The authors have observed no notable prevalence of shin depigmentation in northern Congo, which is infested with S. albivirgulatum flies, but with no onchocerciasis transmission, and where there are also zones of streptocerciasis.