Late-onset onchocercal skin disease among Ethiopian immigrants.

BACKGROUND: Onchocerciasis is an infectious disease caused by the filaria Onchocerca volvulus. Very little is known regarding onchocerciasis imported from endemic to nonendemic areas. OBJECTIVES: To evaluate pruritic dermatitis simulating atopic dermatitis in Ethiopian immigrants in Israel. PATIENTS AND METHODS: A retrospective study of 27 Ethiopian immigrants to Israel was conducted. Demographics and clinical and laboratory data were collected. RESULTS: Of the group of 27 patients, 10 (37%) were men and 17 (63%) were women. The average age at referral was 29 years. All of the patients emigrated from Kuwara, Ethiopia. Diagnosis was done by either positive skin snip test or immunoglobulin (Ig) G4 serology of onchocerciasis in 14 patients. The most common presentation was a combination of lichenified onchodermatitis with atrophy and depigmentation (36%). Eosinophilia and elevated IgE levels were common. Seventeen patients were treated with a single administration of oral ivermectin 200 µg mg(-1). Thirteen patients responded to the treatment. CONCLUSIONS: Immigrants from endemic regions to developed countries presenting with pruritic diseases, especially those with a clinical picture suggestive of atopic dermatitis, should be evaluated for possible onchocerciasis infection. Ivermectin, a relatively safe and low-cost treatment, should be considered even in the absence of a proven disease. Physicians should have a high index of suspicion in patients with the corresponding residential history.

Genetic response to an environmental pathogenic agent: HLA-DQ and onchocerciasis in northwestern Ecuador.

The aim of this study is to explore human leukocyte antigen (HLA)-DQ variability in two populations (Cayapas Amerindians and Afro-Ecuadorians) who live near one another along the Cayapa River and who are exposed to the same environmental stresses, such as infection by Onchocerca volvulus. HLA-DQA1 and HLA-DQB1 of 149 unrelated individuals (74 Cayapas and 75 Afro-Ecuadorians) have been analyzed. HLA high-resolution molecular typing was performed by sequence-based typing, sequence-specific oligonucleotides hybridization and sequence-specific primer (SSP) amplification. The comparison between affected (cases) and unaffected people (controls) in both populations shows the key role of several HLA-DQA1 alleles in susceptibility and protection against onchocerciasis. In both populations, there is strong evidence related to the protective role of DQA1*0401 against onchocerciasis. Alleles HLA-DQA1*0102 and *0103 seem to represent risk factors in Afro-Ecuadorians, while HLA-DQA1*0301 is only a suggestive susceptibility allele in Cayapas. These findings represent new positive/negative associations with onchocerciasis in South America, whereas previous findings pertained only to African populations.

Reduction in the prevalence and intensity of infection in Onchocerca volvulus microfilariae according to ethnicity and community after 8 years of ivermectin treatment on the island of Bioko, Equatorial Guinea.

Bioko is the only island known in the world with endemic onchocerciasis. The island's rural communities consist of villages and cocoa plantations inhabited by Bubi and Fang ethnic groups. The aim of this study was to evaluate the impact of 8 years of vertical ivermectin distribution on the prevalence and intensity of Onchocerca volvulus infection in the rural population by means of pre- (1989) and post-long term treatment (1998) epidemiological surveys. In both surveys, the entire population of 12 randomly selected communities (1723 and 1082 individuals) was examined. The mean ivermectin therapeutic coverage for the 8 years was 53.2%. Iliac crest skin snips were used for differential diagnosis between O. volvulus and Mansonella streptocerca. The crude O. volvulus infection prevalence before ivermectin intervention was 74.5% (1284/1723); after the intervention it was 38.4% (415/1082). The Community Microfilarial Load (CMFL) before and after ivermectin intervention was 28.29 microfilariae/snip vs. 2.32 microfilariae/snip. The reduction in prevalence and CMFL after eight annual rounds of ivermectin treatment corroborates the drug microfilaricidal activity and good tolerability. In the pre-treatment survey, the prevalence was higher in the Bubi group (77.1%, 1126/1461); post-treatment it was higher among the Fang (51.1%, 92/180). The reduction in prevalence and intensity of O. volvulus infection differed between ethnic groups and communities.

Onchocerciasis in Taraba State, Nigeria: clinical-epidemiological study of at-risk males in Bakundi District.

An epidemiological study of 1366 adult males from fourteen communities of Bakundi district of Taraba State, Nigeria was carried out to establish the prevalence and intensity of onchocerciasis. The findings of the study showed that 45.2% of subjects were infected. Ten communities had infection rates in excess of 30%. Lizard skin and leopard skin were seen in 3.5% and 2.0%, respectively, and increased with increasing age. Hanging groin (2.6%) and scrotal enlargement (8.6%) were also observed. There was a good correlation between the infection rate on one hand and the presence of nodules (r = 0.85, P < 0.05), hanging groin (r = 0.56, P < 0.05) and scrotal enlargement (r = 0.62, P < 0.05) on the other. There was also a significant correlation between the intensity of infection on the one hand and lizard skin (r = 0.67, P < 0.05), leopard skin (r = 0.88, P < 0.05) and hanging groin (r = 0.82, P < 0.05) on the other. Those who worked in the fields (such as hunters, farmers and fishermen) had higher infection than others because of frequent contact with the vector. Extensive surveys of all suspected river valleys must be carried out to identify all those communities which will benefit from ivermectin treatment.

Gender and ethnic differences in onchocercal skin disease in Oyo State, Nigeria.

During preparation for a study on the effects of ivermectin treatment on onchocercal skin disease in the Ifeloju Local Government Area of Oyo State, Nigeria, 1032 adults aged 20 years and older were examined for skin lesions and palpable nodules. It was found that for 4 types of skin lesions, acute papular onchodermatitis (APOD), chronic papular onchodermatitis (CPOD), lichenified onchodermatitis (LOD) and depigmentation (leopard skin), as well as for subcutaneous nodules, females had a significantly higher prevalence than males. Although the area is inhabited primarily by the Yoruba people, the study also included some of the cattle-herding Fulani ethnic group. The reactive skin lesions, APOD, CPOD and LOD, were found to be more common among the Fulani, although there were no significant differences in leopard skin and nodules between both groups. While there is need for further research on both immunological and behavioural factors that may lead to these differences in disease. The need to achieve equity in health programming by ensuring that women and ethnic minorities receive full disease control services is of more immediate concern.

Macrofilaricidal effects of chloroquine on adult Onchocerca volvulus by local infiltration of palpable onchocercal nodules.

The macrofilaricidal effects of local infiltration of high concentrations of chloroquine into the capsule of onchocercal nodules on adult worms of Onchocerca volvulus was determined. Six weeks post infiltration, histological examination of single nodules showed all adult worms to be dead. With nodule conglomerates, there was localized action of chloroquine only on the adult worms in the infiltrated nodule, with no diffusion of the drug to adjacent nodules. Chloroquine infiltration of young, recently formed nodules to reduce the adult worm load of infected individuals may be an alternative method to costly nodulectomy.

Social anthropological aspects of onchocercal skin disease in Nebbi District, Uganda.

In providing health care, the busy medical practitioner often lacks the "I-You" quality of the personal experience of illness. This paper reports the perceptions, beliefs and practices of persons living in a hyperendemic focus of onchocerciasis in Nebbi District, north-western Uganda. The study involved the use of focus group discussion and semi-structured interviews designed to explore the experiences, meanings, and illness-related coping strategies employed by the community. The results indicated that oncherciasis is considered to be a mysterious elusive disease which cannot be treated by local herbs. The disease is often mistaken for measles (odyer), and leprosy (dhobu). Persons who suffer from onchocerciasis believed that the cause of the disease is the small black fly (Kamacur), dirty water or rivers. However, non-affected individuals believed that the condition is caused by poor personal and environmental hygiene, and personal contact with persons affected by onchocerciasis. Affected people recommended public health education to control the disease while non-affected people, recommended the avoidance of personal contact with affected people, ensuring personal hygiene, and the improvement of environmental sanitation and the nutritional status of community. The belief systems of the community are probably responsible for the discriminatory practices of the people against those affected by the condition. The results indicate that onchocerciasis is a serious public health problem which needs to be controlled.

Prevalence of onchocerciasis in Blue Nile valley of western Ethiopia.

A epidemiological study of Onchocerciasis among different ethnic groups in the Blue Nile valley of Western Ethiopia was conducted to obtain baseline data on disease prevalence, skin snips samples were obtained from 493 persons, representing different ethnic groups (Nilotic and Oromos), living under different geographic and climatic conditions (lowlands, Midland and highland) or Mendi district for parasitological verification. A total of 169 (34%) had microfilariae of the skin by direct microscopy. The highest prevalence rate (81%) was found among the Nilotic people living along the southern banks of the Blue Nile River. Most patient had wide spread skin infection. Epidemiological differences were also observed.

PIP: The study area was the Blue Nile valley of Mendi District, with 1160 inhabitants within the Wollega administrative region of Ethiopia. The population of 3 villages representing different ethnic groups and residential altitudes were considered. The villages were Gomi (1700 m), Dalati (1200 m), and Siba (700 m) representing highland Oromos, Midland Oromos and Nilotics, and lowland Nilotics, respectively. Out of the total population, a sample size of 493 was selected randomly. Parasitological examination was done with one skin snip, 2-3 mm in diameter, taken from the pelvic girdle and another one from the shoulder area. 169 (34%) of the total 493 examined had onchocerciasis. Only 3 of 101 highland Oromos had microfilaria in the skin, while 130 (81%) of 160 Sirba Nilotic were infected. The Midland Oromos (Dalati) and Dalati Nilotics had infection rates of 6% and 24%, respectively. In the higher altitudes males were more often infected than females, probably because they travel more often to the infected lowland. No such tendency was seen among the Sirba Nilotics who live permanently in the lowland. In all areas, there were increased infection rates in older age. This was most significant in the Sirba and Dafati Nilotics among people above 30 years of age. In all places, positive skin snips were found slightly more often in the lower parts of the body. Out of total 169 infected persons, 46 (27%) had microfilaria in the pelvic girdle only, while 11 (7%) had positive result only in the shoulder area. 112 (66%) had positive skin snips both in the pelvic girdle and the shoulder. All 169 infected persons underwent eye examination. Moving microfilaria were not demonstrated in any of them by slit lamp examination of both eyes. Typical eye changes suggestive of onchocerciasis were not found. There were only 16 typical onchocercoma cases in 12 of the 169 infected persons. 2 of these were in the head, 8 in the shoulder or upper thorax and 6 in the pelvic girdle area. 10 of the 12 people with nodules were Sirba Nilotics.

Antibody responses to Onchocerca volvulus in Ecuadorian Indians and blacks.

In Ecuador, previous epidemiological studies of onchocerciasis affecting a population consisting of Blacks of African origin and Amerindians of the Chachi tribe, have demonstrated different frequencies of clinical disease manifestations in each racial group. To explore the possibility of differential antibody responses to O. volvulus antigens in this population, a subset of sera from these two groups of Ecuadorians with onchocerciasis was analyzed for antibody to O. volvulus antigens using ELISA and Western blot techniques. Significantly higher levels of immunoglobulin against O. volvulus were demonstrated in Chachi Indians compared to native Blacks of African origin: total Ig (p = 0.049), IgG (P = 0.002) IgG4 (p = 0.019) and IgA (p = 0.035). Western blot analysis of sera from 41 persons demonstrated more intense and more frequent recognition of low molecular weight parasite antigens in the Chachi compared to a similar group of male and female Ecuadorian Blacks. These data suggest that the intensity of antibody responses to O. volvulus antigens may reflect the influence of racial factors in the pathogenesis of onchocerciasis in Ecuador.

Onchocerciasis in Ecuador, 1980-1986: epidemiological evaluation of the disease in the Esmeraldas province.

An increase in both the prevalence (68.3%) and intensity of infection (106.2%) occurred in the Ecuadorian onchocercal focus during the 6 year period, 1980 to 1986. In 1986, a higher prevalence of infection was noted in males (53.6%) than females (33.1%), but a greater rate of increase of infection over the 6 years was seen in females than males (75.7% vs 61.9% respectively). In all endemic areas, the Chachi race had a higher prevalence of infection as well as higher increase rate of infection than the Black. In the hyperendemic and hypoendemic areas the highest increase of infection was seen in the Chachi female and Chachi male respectively. The prevalence of infection in 1986 was greater than that in 1980 for all ages, with the greatest increase of infection in the 1-4 year age groups. There was an average increase of 106.2% in the microfilarial skin density with an increase seen in all age groups. A higher microfilariae density increase was seen in the hypoendemic (100.0%) than the hyperendemic (66.5%) areas. The Blacks showed a greater microfilarial density increase than the Chachi (155.1% vs 70.7% respectively) with the Black female showing the highest increase (117.6%) in the hyperendemic area and the Black male showing the highest (155.6%) in the hypoendemic area. Along the Rio Cayapas, high microfilarial densities were found in 3 major areas on the river, a reflection of man-vector exposure.

Onchocerciasis in the Blue Nile Valley of western Ethiopia.

In a survey among 477 inhabitants of the Blue Nile Valley of western Ethiopia 182 (38%) were positive by skin snip investigation for microfilariae of Onchocerca volvulus. Of these only 23% had typical clinical signs and symptoms of onchocerciasis. The highest prevalence rate of microfilariae (84%) was found among Nilotics in the lowlands, where 50% of the children above 10 years, and 90% of adults above 30 years of age, were infected. The mean microfilarial density per skin snip was significantly higher in the high prevalence areas (14) than in the low prevalence areas (3). Positive skin snips from both hip and shoulder were found in 24% of the population, whereas 3% had microfilariae only in the shoulder and 11% only in the hip region. The mean microfilarial density in the hips (16) was double that in the shoulders (8). Ophthalmological evaluation, including slit lamp examination, was possible in 77 of the 182 cases with positive skin snips. Severe eye damage due to onchocerciasis was not observed. However, one 35 year old female had live microfilariae in the anterior chambers of both eyes.