Onchocerciasis, an undiagnosed disease in Mozambique: identifying research opportunities.

BACKGROUND: The objective of this paper is to summarise and critically review the available data about onchocerciasis in Mozambique, in order to report epidemiological and clinical aspects related to the disease and identify gaps in knowledge. The paper is intended to raise awareness of the existence and importance of this disease and to define research priorities. METHODS: We examined the scarce epidemiological data at our disposal: two diagnostic studies in 1997 and 1998 (first reports on the existence of onchocerciasis in Mozambique), and two Rapid Epidemiological Mapping of Onchocerciasis (REMO) surveys in 2001 and 2007. We examined differences in study designs and methodologies as well as the differing geographical locations to explain the divergence in findings among the studies. RESULTS: Evidence indicates that onchocerciasis is hypoendemic in Mozambique (with national and imported cases), but still largely remains an undiagnosed illness. There is no awareness of the clinical aspects of the disease and nor of the differential diagnosis with lepromatous leprosy and dermatitis caused by Scabies spp. The use of skin biopsy and a symptom screening questionnaire, combined with nodule rate, in the first two studies may have captured even atypical or subacute presentations. Both REMO surveys relied solely on nodule detection and in the six years between the two studies, the prevalence of nodules detected more than doubled. CONCLUSIONS: The epidemiology and clinical aspects of the disease are unknown in Mozambique. Since the last REMO took place in 2007 and since the population is subject to large-scale movement and displacement, it is important to develop tools to identify and analyse populations that are at high risk for onchocerciasis. Cases of onchocerciasis may be misdiagnosed as leprosy or scabies that fail to improve despite being subjected to treatment against leprosy. Techniques to enable a differential diagnosis need to be established by training health professionals on the recognition of this undiagnosed disease. It is equally necessary to identify the blackfly vectors and where they breed.

Anti-desmoglein-1 antibodies in onchocerciasis, leishmaniasis and Chagas disease suggest a possible etiological link to Fogo selvagem.

Pemphigus foliaceus (PF) and the endemic form Fogo Selvagem (FS) are mediated by pathogenic antibodies to the EC1-2 domains of desmoglein-1. There is a preclinical phase with antibodies to only EC5. Based on geographic clustering of cases, FS is thought to have an, as yet unidentified, environmental trigger. In this study we have searched for anti-desmoglein-1 antibodies in sera from parasitic (leishmaniasis, Chagas, and onchocerciasis), and infectious diseases (leprosy and South American (SA) blastomycosis), which are prevalent in the same geographic regions of Brazil as FS. A specific and sensitive desmoglein-1 ELISA detected antibodies in 34 of 41 onchocerciasis (83%), 38 of 88 leishmaniasis (43%), 18 of 31 Chagas disease (58%), 7 of 28 SA blastomycosis (25%), and 14 of 83 leprosy sera (17%). These sera recognized epitopes restricted to the EC5 domain. These findings identify several etiological factors for FS. It is hypothesized that a component of insect vector saliva, rather than the parasite itself may trigger an antibody response to EC-5. In persons with the known HLA susceptibility alleles and living in endemic areas, a response to the EC1-2 domains may subsequently develop by epitope spreading with associated clinical signs of FS.

Corneal blindness: a global perspective.

Diseases affecting the cornea are a major cause of blindness worldwide, second only to cataract in overall importance. The epidemiology of corneal blindness is complicated and encompasses a wide variety of infectious and inflammatory eye diseses that cause corneal scarring, which ultimately leads to functional blindness. In addition, the prevalence of corneal disease varies from country to country and even from one population to another. While cataract is responsible for nearly 20 million of the 45 million blind people in the world, the next major cause is trachoma which blinds 4.9 million individuals, mainly as a result of corneal scarring and vascularization. Ocular trauma and corneal ulceration are significant causes of corneal blindness that are often underreported but may be responsible for 1.5-2.0 million new cases of monocular blindness every year. Causes of childhood blindness (about 1.5 million worldwide with 5 million visually disabled) include xerophthalmia (350,000 cases annually), ophthalmia neonatorum, and less frequently seen ocular diseases such as herpes simplex virus infections and vernal keratoconjunctivitis. Even though the control of onchocerciasis and leprosy are public health success stories, these diseases are still significant causes of blindness--affecting a quarter of a million individuals each. Traditional eye medicines have also been implicated as a major risk factor in the current epidemic of corneal ulceration in developing countries. Because of the difficulty of treating corneal blindness once it has occurred, public health prevention programmes are the most cost-effective means of decreasing the global burden of corneal blindness.

Stigma associated with onchocercal skin disease among those affected near the Ofiki and Oyan Rivers in western Nigeria.

Skin diseases have been a major source of social stigma, whether they be infectious or not. The potential stigamtizing effect of skin disease associated with onchocerciasis is currently receiving attention because half of the 17 million victims of onchocerciasis in Africa live where the non-blinding form of the disease is prevalent. Some reports are available that onchocercal skin disease (OSD) is associated with social stigma including problems in finding a marriage partner. Previous studies have also implied positive effects of ivermectin treatment on OSD. Therefore a multi-country trial of ivermectin is underway to test the hypothesis that ivermectin treatment might affect perceptions of stigma associated with OSD. This paper presents the baseline stigma findings from the study site located in southwestern Nigeria. A total of 1032 persons living in villages near the Ofiki and Oyan Rivers were screened and interviewed and 500 (48%) were found to have an onchocercal skin lesion. A 13-item, 39-point stigma scale was used in interviews with affected persons. A mean score of 16.8 was obtained. No personal characteristics or disease factors were found to be associated with stigma score. The highest ranking items focused on issues of self-esteem such as feeling embarrassed, feelings of being pitied, thinking less of oneself, feeling that scratching annoys others, feeling that others thought less of the person and feeling that others had avoided the person. During the interviews it was discovered that only about half of those clinically diagnosed as having OSD labeled their own condition as onchocerciasis. Those who said their lesion was OSD had a lower stigma score than those who did not, conforming with previous studies wherein affected persons perceived less stigma from OSD than those without the disease. A broader community perspective on OSD was obtained through 50 interviews using paired comparisons of five skin-related local illnesses. Onchocerciasis placed midway in aversive responses between the higher end represented by leprosy and chicken pox and lower scoring papular rashes known locally as eela and ring worm. In-depth village based interviews yielded several case studies of how onchocerciasis had a negative social impact on its victims. While study on the cultural perceptions of OSD is recommended, the results indicate that with a fairly high prevalence of OSD, the community level effects of social stigma should be regarded as serious.

Manuel Martínez Báez: una visión muy personal de las enfermedades tropicales / Manuel Martínez Báez: a very personal view of tropical diseases

La obra del doctor Manuel Martínez Báez (1894-1987) es muy vasta y se agrupa claramente en torno a tres áreas de la medicina: Parasitología, salud pública y sociología médica e historia de la medicina. Este trabajo estudia un aspecto de su ideología en salud pública y sociología médica, el relativo a las enfermedades tropicales. La aportación de Martínez Báez en está área fue relevante porque adecuó a la realidad de los países subdesarrollados los conceptos que sobre enfermedades tropicales surgieron en países ajenos a esta problemática

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.

International task force for disease eradication

The eradication of smallpox from the world in 1977 proved the feasibility of infectious disease eradication. The International Task Force for Disease Eradication (ITFDE) is assessing the potential for global eradication of other infectious diseases. This report summarizes the ITFDE's findings on the potential to eradicate eight diseases based on draft versions of criteria under development (AU)

[Paraclinical study of onchocercosis in a leprous and non-leprous population]. / Etude paraclinique de l'onchocercose en population lépreuse et non lépreuse.

In a survey dealing with the frequency of onchocerciasis in leprous environments in the Marchoux Institute in Bamako (Mali) evidence is given that 43% of the leprous persons hospitalized there were touched in addition by onchocerciasis whereas, only 14% of the consultants in dermatology have proved to be also onchocercian. This last frequency is consistent with the overall estimation usually recognized for Mali. No difference was shown between leprous and non-leprous persons for snip. In contrast, 33% of microfilariae bearing leprousians showed no positive reaction to diethylcarbamazine whereas no more than 5% of non-leprous persons displayed similar negative response. Similarly leprousian blood yielded most often the microfilariae of Onchocerca volvulus. Surprisingly, hypereosinophilia has proved to be normal or null in 37% of microfilariae bearing leprosians. Though aware of the occurrence of numerous real or possible biases in such an approach the authors wonder what meaning such a difference between leprous populations and non-leprous ones in Mali can have. If a relation is definitely borne out in the future between both pathologies, they further wonder whether leprosy is the bed of onchocerciasis or vice versa.

The secular changes of skin and venereal diseases in Nigeria.

A retrospective review of the changing phase of the incidence of dermatological and venereal diseases, as seen in University Teaching Hospital practice in Lagos, Nigeria is presented. About 8,849 new patients were seen over a 5-year-period. An analysis of the dermatological conditions encountered is made, while brief reports of few common skin conditions are also given. The clinical pattern was similar to those of Western countries, but with addition of a great number of dermatoses. This similarity has been modified by epidemiological factors. A national program for improvement of the environmental health including control of industrial and communicable diseases will ameliorate the increasing morbidity of tropical dermatology.