Hermann Feldmeier

Tungiasis: a neglected health problem of poor communities

Tungiasis is caused by the flea Tunga penetrans. Growing urbanization, improved housing and use of appropriate footwear presumably have led to an overall reduction of the occurrence of this ectoparasitosis within the last decades. However, it is still highly prevalent where people live in extreme poverty, occurring in many Latin American and African countries. Although the infection has long been known, data on the ectoparasite’s biology and the epidemiology of the disease are scant. Methods for treatment, prevention and control have never been evaluated in a scientific manner. Tungiasis remains an important public health problem for the very poor, a problem neglected by those who are affected, by the medical profession and by the scientific community.

Bacterial superinfection in human tungiasis.

Tungiasis is caused by penetration of the female sand flea Tunga penetrans into the epidermis of its host. It is endemic in many countries in Latin America, the Caribbean and sub‐Saharan Africa. Although superinfection is a common clinical observation, the frequency and the pattern of bacterial pathogens associated with tungiasis have never been investigated systematically. We conducted a prospective clinico‐bacteriological study with patients living in a shantytown in Fortaleza, capital of Ceará State (Northeast Brazil), where tungiasis is hyperendemic. Swabs were taken from 78 patients with multiple lesions after surgical extraction of the parasite, and the specimens were cultured for aerobic and anaerobic microorganisms. Ninety‐nine specimens were investigated for aerobic bacteria, from which 146 pathogens were identified. The most common species were Staphyloccous aureus (35.5%) and various enterobacteriaceae (29.5%). Bacillus sp., Enteroccous faecalis, Streptococcus pyogenes and Pseudomonas sp. were also isolated. Eighty‐four anaerobic cultures yielded 20 pathogens: in eight cases we detected Peptostreptococcus sp., in seven cases Clostridium sp., and in five cases non‐identifiable gram‐negative bacilli. These results show that secondary infection is very common in tungiasis, and caused by a variety of highly pathogenic microorganisms. It is proposed that T. penetrans acts as a foreign body facilitating biofilm formation within the epidermis. To prevent spreading of pathogens to the surrounding tissue and/or the systemic circulation, sand fleas should be surgically extracted immediately after penetration.

FEMALE GENITAL SCHISTOSOMIASIS: FACTS AND HYPOTHESES

In this paper we summarise the parasitological, clinical and epidemiological characteristics of female genital schistosomiasis (FGS), a frequent manifestation of the infection with Schistosoma haematobium. Means to diagnose and treat lesions in the lower and upper genital tract are discussed. Based on clinical findings and available pathophysiological as well as immunological data it is conceivable that FGS of the cervix and vagina not only facilitates the infection with agents of sexually transmitted diseases, but presumably also alters the natural history of such infections. Two infectious agents are of particular concern: the Human Immunodeficiency Virus and the oncogenic Human Papilloma Viruses. Possible interactions and their consequences are discussed and research areas which should be addressed are outlined.

Diagnostic techniques in schistosomiasis control. A review

Diagnosis is central to all aspects of schistosomiasis. Decisions on individual and community treatment, estimations on prognosis and assessment of morbidity, evaluation of chemotherapy and control measures all require the results from diagnostic tests. Unfortunately, all presently available techniques are characterised by diagnostic imperfections. Selection and application of methods should therefore correspond to the type of information sought by the public health officer or the epidemiologist and interpretation of test results must take into consideration the drawbacks and constraints inherent to each of the various diagnostic approaches.

Female Genital Schistosomiasis of the Lower Genital Tract: Prevalence and Disease-Associated Morbidity in Northern Tanzania

Female genital schistosomiasis (FGS) is a neglected disease manifestation of schistosomiasis. A cross-sectional study was carried out to assess in a schistosomiasis-endemic area the proportion of women affected by FGS of the lower reproductive tract and to compare the frequency of symptoms and signs possibly associated with FGS between women with proven FGS (n=134), endemic referents (n=225, women living in an endemic site), and referents (n=75, women living in a nonendemic site). Urinary schistosomiasis was diagnosed in 36% (239/657) and FGS in 37% (134/359) of the women. Cervical lesions occurred in 75% of the FGS cases, in 48% of endemic referents, and in 36% of nonendemic referents. The high prevalence of FGS in all age groups and the high levels of pathologic cervical alterations such as swollen and disrupted epithelium support the hypothesis that FGS might be a risk factor for the transmission of human immunodeficiency virus.

Epidermal parasitic skin diseases: a neglected category of poverty-associated plagues

Epidermal parasitic skin diseases (EPSD) are a heterogeneous category of infectious diseases in which parasite-host interactions are confined to the upper layer of the skin. The six major EPSD are scabies, pediculosis (capitis, corporis and pubis), tungiasis and hookworm-related cutaneous larva migrans. We summarize the current knowledge on EPSD and show that these diseases are widespread, polyparasitism is common, and significant primary and secondary morbidity occurs. We show that poverty favours the presence of animal reservoirs, ensures ongoing transmission, facilitates atypical methods of spreading infectious agents and increases the chances of exposure. This results in an extraordinarily high prevalence and intensity of infestation of EPSD in resource-poor populations. Stigma, lack of access to health care and deficient behaviour in seeking health care are the reasons why EPSD frequently progress untreated and why in resource-poor populations severe morbidity is common. The ongoing uncontrolled urbanization in many developing countries makes it likely that EPSD will remain the overriding parasitic diseases for people living in extreme poverty. We advocate integrating control of EPSD into intervention measures directed against other neglected diseases such as filariasis and intestinal helminthiases.

The animal reservoir of Tunga penetrans in severely affected communities of north-east Brazil

Abstract.  Tungiasis is a zoonotic ectoparasitosis caused by the sand flea Tunga penetrans L. (Siphonaptera: Tungidae). This disease is hyperendemic in poor communities of north‐east Brazil, causing considerable morbidity in affected human populations, but the animal reservoirs have not been investigated previously in Brazil. To assess the prevalence and intensity of T. penetrans infection in domestic and peri‐domestic animals, as well as in the human population, we surveyed two typical communities of north‐east Brazil: an urban slum and a traditional fishing village. In the slum we examined 849 humans, 121 cats, 82 dogs, 2 pigs, 2 rabbits, 1 monkey and 56 rodents, comprising 34 rats (Rattus rattus L.) and 22 mice (Mus domesticus L). In the fishing village we examined 505 humans, 68 dogs, 37 cats, 7 donkeys, 4 cattle, 3 pigs and 1 monkey. Tungiasis was common among dogs and cats of both communities, with respective prevalence rates of 67.1% (95% CI: 55.8–77.1) and 30.9% (95% CI: 20.2–43.3) in dogs, 49.6% (95% CI: 40.4–58.8) and 32.4% (95% CI: 18.0–49.8) in cats. Slum rats were 41.2% (95% CI: 24.6–59.3) infested, but the other animals were not. Human prevalence rates were 54.4% (95% CI: 51.0–57.8) in the slum and 52.1% (95% CI: 47.6–56.5) in the fishing village. High prevalence rates (range 31–67%) of tungiasis in humans, pets and rats (but apparently not other animals) indicate the need for an eco‐epidemiological approach to control of this anthropo‐zoonotic problem.

Female genital schistosomiasis due to Schistosoma haematobium Clinical and parasitological findings in women in rural Malawi

A total of 51 women with urinary schistosomiasis haematobium were examined in order to identify diagnostic indicators for female genital schistosomiasis (FGS). Patients were selected at random from the outpatient department of the Mangochi District Hospital, Malawi. The medical histories were recorded according to a pre-designed questionnaire and the women were subjected to a thorough gynaecological examination including colposcopy and photographic documentation of lesions. Microscopy of genital biopsies revealed that 33 of the 51 women had S. haematobium ova in cervix, vagina and/or vulva in addition to the presence of ova in urine. The most sensitive diagnostic procedure was beside microscopic examination of a wet cervix biopsy crushed between two glass slides, which revealed 25 of the 33 genital infections. There was a significant correlation between the size of genital lesions and the number of ova counted per mm2 of crushed tissue. Women with FGS had significantly more tumours in the vulva than women with schistosomiasis limited to the urinary tract. Most of the observed genital pathology could easily be identified by the naked eye, but colposcopic examination yielded valuable additional information like the demonstration of neovascularisation around cervical sandy patches. Few of the symptoms previously regarded as indicators for FGS could be linked to the presence of schistosome ova in genital tissue. Husbands of infertile women with FGS had children with other women significantly more often than husbands of women who only had urinary schistosomiasis. This, together with the finding that the majority of the divorced women had FGS, indicates that the manifestation of this disease may have implications for the marital and sexual life of the affected women.

Parasitic skin diseases: health care-seeking in a slum in north-east Brazil.

Ectoparasitic diseases are endemic in many poor communities in north‐east Brazil, and heavy infestation is frequent. We conducted two studies to assess disease perception and health care seeking behaviour in relation to parasitic skin diseases and to determine their public health importance. The first study comprised a representative cross‐sectional survey of the population of a slum in north‐east Brazil. Inhabitants were examined for the presence of scabies, tungiasis, pediculosis and cutaneous larva migrans (CLM). The second study assessed health care seeking behaviour related to these ectoparasitoses of patients attending a Primary Health Care Centre (PHCC) adjacent to the slum. Point prevalence rates in the community were: head lice 43.3% (95% CI: 40.5–46.3), tungiasis 33.6% (95% CI: 30.9–36.4), scabies 8.8% (95% CI: 7.3–10.6) and CLM 3.1% (95% CI: 2.2–4.3). Point prevalence rates of patients attending the PHCC were: head lice 38.2% (95% CI: 32.6–44.1), tungiasis 19.1% (95% CI: 14.7–24.1), scabies 18.8% (95% CI: 14.4–23.7) and CLM 2.1% (95% CI: 0.8–4.5). Only 28 of 54 patients with scabies, three of 55 patients with tungiasis, four of six patients with CLM and zero of 110 patients with head lice sought medical assistance. The physicians of the PHCC only diagnosed a parasitic skin disease when it was pointed out by the patient himself. In all cases patients were correctly informed about the ectoparasitosis they carried. The results show that tungiasis and pediculosis, and to a lesser extent scabies and CLM, are hyperendemic but neglected by both population and physicians, and that prevalence rates of tungiasis and scabies at the PHCC do not reflect the true prevalence of these diseases in the community.

High prevalence of tungiasis in a poor neighbourhood in Fortaleza, Northeast Brazil

Tungiasis has been reported to occur in many Latin American, Caribbean and African countries. However, epidemiological data are still very scanty and do not exist at all for Brazil. To fill this gap, a cross-sectional study has been undertaken in a shantytown (favela) in Fortaleza, Ceará State, northeast Brazil. All 327 households of a circumscribed sub-area were visited, and 1185 out of the 1460 household members were thoroughly examined for the presence of tungiasis. Thirty-four% (95% CI: 30.9-36.4) were found to be infected with Tunga penetrans with a significant preponderance of the male sex (p<0.0001). In the children five to nine years old, the age group most heavily affected, the prevalence rate was 65.4% (95% CI: 54.0-75.7) in boys and in 48.3% (95% CI: 37.4-59.2) in girls. The data show that tungiasis is hyper-endemic in the study area. As the favela is typical for the many poor communities in northeast Brazil, it can be assumed that tungiasis is a frequent infection in the underprivileged in this part of the country.