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close this book Opportunities for Control of Dracunculiasis (1982)
close this folder Overview of Dracunculiasis
View the document Etiology And Life Cycle
View the document Clinical Symptoms And Treatment
View the document Social And Economic Effects
View the document Control Measures

Clinical Symptoms And Treatment

Infected people exhibit no signs or symptoms until the female worm matures and is ready to emerge. The first manifestation of dracunculiasis is localized swelling at the spot where the mature worm will emerge. In over 90 percent of cases, it emerges somewhere on the legs or feet, although worms may emerge from any part of the body. Intense burning or itching accompanies the swelling, which develops into a blister within l or 2 days. This blister ruptures several days later and becomes a superficial ulcer. Infected people often immerse the lesion in water in an effort to relieve discomfort. The worm's uterus expels larvae when the affected part is exposed to water, a process that may continue for several days to 3 weeks. Occasionally worms die before reaching the skin's surface and are absorbed, form aseptic abscesses, or become calcified, leaving cordlike masses.

Generalized nonspecific symptoms may accompany the appearance of Dracunculus at the skin, but they are usually not severe. Such symptoms may include diarrhea, vomiting, skin rashes, or asthma.

The tissues near the blister become swollen, red, and very tender, probably as part of a largely allergic reaction. There is usually a secondary infection, which commonly spreads from the initial skin lesion to deeper tissues and may be accompanied by severe or fatal septicemia. Infected ankle and knee joints can become contracted, leading to permanent crippling. Even in cases uncomplicated by secondary infection of the ulcer, the affected person may find it very difficult to walk and thus must give up his usual labors. On average, about 4-6 weeks elapse before an uncomplicated infection heals completely.

Less frequent are other severe conditions or death resulting from Dracunculus infection. These conditions include septic arthritis, tetanus, gangrene, pulmonary scarring, and ophthalmic disease.

A person may be infected by several guinea worms at the same time. Although each infection lasts a year, no effective immunity develops, and people at risk may be repeatedly infected year after year.

Because of its unusual manifestation, guinea worm disease is easily diagnosed once the worm is ready to emerge. Diagnostic tests to detect the presence of Dracunculus at earlier stages have not been developed for routine use. However, laboratory investigators have reported positive fluorescent antibody tests 6 months or more before emergence of the worm (Belcher 1981). Another nonspecific aid to diagnosis may be eosinophilia of 10-15 percent. In general, however, very little biomedical research on dracunculiasis has been carried out, thus making interpretation of findings reported in the literature quite difficult.

No drugs have proved effective in killing the adult worm prior to emergence, although some have shown experimental promise in reducing inflammation and facilitating extraction of the worm. Niridazole, metronidazole, thiabendazole, levamisole, bitoscanate, and mebendazole have been tested in humans within the last 7 years. Of these compounds, only thiabendazole is given as a short (2-day) course of treatment, which would make patient compliance more likely. One study reported that mebendazole (7-day course) resulted in significant symptomatic improvement. The action of niridazole appears to be largely one of reducing inflammation. For the most part, however, these drugs are expensive and may not be available locally. Large-scale controlled clinical trials have not been conducted, and the results of the smaller studies are difficult to interpret because of different patient selection methods, wide variation in criteria of efficacy, lack of control groups, and high drop-out rates.

The majority of infected people neither seek nor receive medical care from qualified physicians or nurses. Patients often consult healers or resort to the traditional technique of extracting the worm by rolling it a few centimeters each day around a stick or gauze (Figure 2). Infection often results if the worm breaks. Some physicians prescribe chemotherapy and make multiple incisions under local anesthesia to extract the emerging worm. Antibiotics may be given to treat secondary bacterial infections, and tetanus prophylaxis is strongly advocated.

Epidemiology

Adults between the ages of about 16 and 45 years are usually most heavily infected, although a considerable proportion of children over 5 years of age may also be affected. Young children and very old people are much less likely to acquire the disease, possibly because they do not drink as much from contaminated shallow ponds and wells near agricultural fields (Figure 3).

Because of its life cycle and the year-long incubation period, the transmission and clinical manifestations of dracunculiasis are highly seasonal. Transmission occurs only under certain climatic conditions and varies according to the local rainfall pattern. In very dry areas such as the Sahel of West Africa, transmission generally is limited to the few months during the rainy season when surface sources of drinking water become available and are used, with consequent infections becoming clinically apparent during the same period a year later. In other areas such as southern Nigeria, where rainfall is much more substantial and prolonged, the disease is most evident and is transmitted during the dry season, when surface water sources are much more scarce and contain higher concentrations of cyclops (Figure 4). Severe droughts have been known to interrupt transmission for periods sufficient to cause the disease to decline or even disappear naturally. In areas where step wells and open cisterns are used, transmission periods tend to be longer due to the persistence of cyclops in larger numbers. Because of variable transmission seasonality, local case data is important in planning control activities.


Figure 3: Age distribution of people affected by dracunculiasis (Source: Belcher et al. 1975)

Geographically, dracunculiasis occurs only in the Old World, mainly India and West Africa (Figure 5). In India the disease is limited to six states in the western part of the country; about half of the cases are reported from Rajasthan State (Figure 6). Transmission in Tamil Nadu State appears to have been interrupted recently by long-standing control measures (World Health Organization 1983). India is the only country that has actively searched for cases of dracunculiasis, and the numbers of cases reported from India are the most complete and reliable data available on the incidence of the disease (Table 1). The reported surveillance data from other countries give only an approximate indication of the most highly affected areas.

In West Africa, where probably less than 10 percent of cases are reported, the zone of highest endemicity includes Ivory Coast, Ghana, Togo, Benin, Nigeria, Mali, Niger, and Upper Volta. Questionnaire surveys are under way or have recently been conducted in Ghana, Nigeria, and Benin. Preliminary indications are that Oyo, Ondo, and Anambra may be the moat severely affected of the 16 endemic states in Nigeria, while Cross River, Rivers, and Lagos states are apparently free from the disease. According to another preliminary report, an estimated 600,000 people are affected by dracunculiasis in Benin. Niamey, Niger, appears to include the only significant urban focus of the disease (over 3,000 cases reported in 1979). Migration of infected Moshi tribesmen and women to the forest zone in Ivory Coast is thought to have spread the disease in the latter area. The most highly affected areas of Upper Volta are Banfora, Dori, Koudougou, Ouagadougou, Oushigouya, Yako, and Tenkodogo. In Ivory Coast, most cases were reported from Bouake, Boufile, Dimbokro, Tiassale, Bondoukou, and Seguela. Tsevie, Notse, and Bassari appear to be the most highly affected administrative areas in Togo.

Provision of safe water supplies by drilling wells in the rural health sector of Dimbokro, Ivory Coast, is said to have recently reduced the prevalence of dracunculiasis there from 30 percent to approximately 1 percent. A similar reduction is reported from an area of Bendel State in Nigeria. In Mali it is reported that dracunculiasis disappeared from the village of Guirel (in northern Nara) after a drought dried up the local pond for 2 consecutive years.


Figure 4: The impact of dracunculiasis on a community in southern Nigeria. Transmission is greatest during the dry season when surface water sources are scarce and contain higher concentrations of cyclops (Source: Kale 1977)

Although the disease is known to be endemic in southern Sudan, that country is the only mayor affected area where no recent surveillance information is yet available. With the probable exception of southern Sudan, the infection appears to be limited to small parts of only a few countries in East Africa and the Middle East. In Pakistan in 1969, dracunculiasis reportedly was limited to two areas involving five districts in the north-central and extreme southeast regions of the country. In 1983 Iran informed the World Health Organization that there had been no dracunculiasis in the country for the past 5 years, despite continued surveillance.


Figure 5: Areas in which dracunculiasis is reported or probably exists (Source: World Health Organization 1982)

Although the disease is easily diagnosed, and thus recognition of the problem is relatively simple, surveillance of dracunculiasis, paradoxically, is exceptionally poor. The lack of ongoing case information is due in part to the remote rural nature of affected populations, their limited attendance at government clinics, and the low government priority accorded to dracunculiasis. This situation could continue since the absence of a specific curative or preventive drug or vaccine removes a treatment incentive for villagers to visit health centers where their infection might be diagnosed and officially reported. In most endemic zones, less than 5 percent of cases are reported. Millions of cases are thought to occur annually worldwide, but systematic epidemiologic surveillance is needed to produce a reliable estimate of the annual global incidence.


Figure 6: Dracunculiasis endemicity in India (June 1982). About half of the cases are reported from Rajahstan State. (Source: World Health Report 1983)

TABLE 1 Reported Cases of Dracunculiasis in India (up to June 1982)

State

Number of Cases

Rajasthan

14,905

Karnataka

4,211

Maharashtra

3,776*

Madhya Pradesh

3,542*

Andhra Pradesh

3,049

Gujarat

423

Tamil Nadu

0

Goa

n.a.

Total

29,906