Dr André Stanghellini 4 Le Bourg Nord, 33660 Puynormand, France
Although nearly one-fifth of the Angolan population is at risk of becoming infected with trypanosomiasis, only 6% currently have access to surveillance and treatment because of the war and its resultant destruction of the country’s infrastructure. The paper outlines the history of human African trypanosomiasis (HAT) control activities in Angola and sums up what measures need to be taken to re-establish them.
Trypanosomiasis has been known in Angola since the end of the nineteenth century when the disease was identified in the region of Quixama, south of Luanda along the river Kwanza. The struggle against this endemic disease started in a very rudimentary way in 1901 with the mission directed by Dr Anibal Beltencourt. In 1926, the ‘Service for Medical Assistance to the Indigenous and Combat against Sleeping Sickness’ was founded. In 1946 a mobile team under the dynamic management of Dr Luis Pinto Fonseca was introduced to provide curative and prophylactic services. In 1952, a ‘Brigade for Pentamidinization’ was created and 26 health sectors established in the endemic zones (Zaïre, Uíge, Bengo and Kwanza Norte). As a result, in 1974, at the dawn of independence, only three new cases were actively detected in the entire country.
The National Program created in 1978 never became fully operational due to the emigration of officers, lack of equipment and vehicles, and because the medical facilities dedicated to trypanosomiasis were destroyed. Support of the Swedish Agency for International Development (ASDI) from 1982 to 1992 allowed to resume activities against the endemic, but the working capacities of the Program were again destroyed during the post-electoral civil war. After the signing of the Lusaka Protocol in 1994, screening and treatment activities began again in certain zones of endemic transmission (thanks to the presence of Médecins sans Frontières France and Belgium, Caritas, Norvegian Peoples Aid and Médecins du Monde Catalunya). The headquarters of the National Program was supported in its efforts of restructuration by the French Cooperation since 1997 and became the Instituto de Combate e de Controlo das Tripanossomíases in the year 2000.
Since June 1998, a new flaring-up of armed conflict, especially in the zones of trypanosome transmission, has again been endangering all efforts of disease control. Its overall results, from 1949 until today, are shown in Figs 1 and 2 (Josenando 1994a).
The current situation
The total population of Angola is about 12 million, of whom an estimated 4 million live in the affected provinces Zaïre, Uíge, Bengo, Kwanza Norte, eastern Malange and northern Kwanza Sul (Fig. 3). About 2.5 million are at risk of contracting the disease. Despite all efforts during the last years to resume activities to combat the disease, only a very small proportion (6%) of the population at risk is covered by surveillance.
The overall results of the screening activities from 1994 to 1998 are summarized in Table 1. They show the constant progression of the number of persons examined for trypanosomiasis from 4274 in 1994 to 157 400 in 1998. The number of cases detected has also increased from 1994 to 1997 (1274–8275). In 1998 a reduction (6610 cases) occurred despite the almost doubled number of people visited in comparison with 1997. This reduction is partially caused by the stop of passive surveillance in certain centres which were destroyed and looted. Another cause is the impact on transmission of active screening undertaken, particularly in the regions of Dondo, N’Dalatondo and Lucala.
Table 1. Total population screened annually between 1994 and 1998
The detailed results of the active screening of the years 1997–98 are summarized in Table 2. Although the number of people examined increased, it remains insignificant in view of the overall number of people at risk. The prevalence varies between 0.9 and 9.7% depending on the zone prospected. If the prevalences per village are considered, figures as high as 16% are reported, e.g. in Lucala and Kizenga. UNITA (National Union for the Total Independence of Angola) soldiers were screened from March 1996 to April 1997 in quarters erected by UCAH (United Nations Humanitarian Assistance Coordination Unit) after the peace accord of Lusaka. The prevalence of parasitologically confirmed sleeping sickness in this population was 1.3–1.7% in known trypanosomiasis foci, and 0% in regions not affected as well as in the Glossina morsitans area in the south.
Table 2. New cases detected annually between in 1997 and 1998
Of the 6610 cases actively detected in 1998, 4841 were in the second stage of the disease (73.2%) and 1769 (26.8%) in first stage. These figures give evidence that immense efforts are necessary to inverse this ratio and gain control over transmission. The goal is surveillance and treatment of the total population at risk; which would require 30 fixed centres, 21 mobile teams and about 500 technicians – tremendous financial and human resources. A programme this size would cover and treat the estimated 100 000–120 000 patients infected with trypanosomes in the foci of the country.
Of the 10 centres and five mobile teams which are presently operational, some operate under difficult circumstances as a result of the interior situation in the country. The total number of technicians employed is unknown as most of them work for NGOs (Josenando & Stanghellini 1998).
Data on cases detected in the G. morsitans area situated in the southern province of Cuando-Cubango are available until 1973. From 1964 to 1973, 430 new cases were diagnosed in Angola, of whom 150 patients (35%) originated from the G. morsitans area. Since then no new information has been available, except from military quarters, as the entire region was under the control of UNITA.
Reasons for recrudescence of the disease
The return of sleeping sickness is essentially a consequence of the war, which has disrupted and undermined the implementation and sustainability of disease control activities through several factors: migration of populations between provinces and from one zone to another, especially into the cities and the capital; inaccessibility due to insecurity and landmines – on the one hand patients cannot reach centres for diagnosis and treatment and on the other hand, the movement of mobile teams to the villages in the foci is restricted; damage to the buildings of health care facilities or looting of technical resources such as drugs, microscopes or vehicles; pressure on the national budget due to the war expenses, which can no longer suffiently support the health sector, particularly trypanosomiasis control; demotivation of health personnel caused by inflation.
Measures of combat and control
The strategy of the National Program combines activities against the parasite reservoir by active screening and treating patients with antivector campaigns against tsetse flies (Glossina). Case detection is simultaneously based on passive surveillance by stationary diagnostic and treatment facilities, and on active screening of the population by mobile screening teams. Primary screening comprises CATT-testing of the complete population visited by the teams or of those who are spontaneously present for consultation.
Those who are serologically positive undergo parasitological examination of the lymph fluid after lymph node puncture, and of full blood after it has been centrifuged in a heparinized capillary tube. In serologically positive cases which cannot be confirmed parasitologically, a titration of serum with the CATT is performed: those with a titre equal to or higher than 1/8 are considered infected with trypanosomes. All new cases so detected have a lumbar puncture for staging of the disease. Cases with up to 20 white blood cells (WBC) per mm3 in the cerebrospinal fluid (CSF) are considered to be at an early stage and are treated with pentamidine. Those with more than 20 WBC/mm3 or trypanosomes, independent of the number of WBC, are considered to be in late-stage and are treated with melarsoprol. The cut-off for the definition of late-stage used to be 5 WBC/mm3 (WHO 1986; Josenando 1994b), but was changed to 20 WBC/mm3 at the beginning of 1999 based on recent research results (Pepin et al. 1989, 1992; Doua et al. 1996; Miezan et al. 1998).
All patients are treated in health centres which are responsible for treatment and follow-up examinations. All late-stage cases receive melarsoprol following a protocol of three series of four injections of Arsobal® (Aventis, France) (1.2, 2.4, 3.6, 3.6 mg/kg each), the injections spaced by 24 h, the series being spaced by 7 days. First-stage cases are treated ambulatorily with a total of seven injections of pentamidine isethionate (4 mg/kg) every other day.
In the focus of M’banza Congo, 25% of the cases treated with melarsoprol remain parasitologically positive in the CSF or relapse within 1 month, and must be considered treatment refractory. The mechanisms leading to the increased rate of failures of melarsoprol treatment are unknown and currently under investigation. A detailed discussion of current thinking and investigations, and results of pharmacokinetic investigations in patients from M’banza, Congo, may be found in the paper by Burri & Keiser (2001). When available, DFMO (Eflornithine) was used to treat patients refractory to treatment with melarsoprol. Of 85 patients reported, 63 (74%) were free of parasites and showed marked clinical improvement at the end of the treatment course, but no data are available on their follow-up. Regrettably, this useful medication, even if very expensive, is no longer produced. As an alternative it is envisaged to test nifurtimox for those cases in a case–control study (Pepin et al. 1989, 1992; Van Nieuwenhove 1988, 1992).
Combating tsetse flies by constant trapping (Lancien type) in targeted areas with active community participation is the second measure to cut the transmission chain. Two preliminary studies were conducted in certain zones of high prevalence (Dondo in Kwanza Norte and M’banza Congo in Zaire), but the political and military situation and the presence of landmines does not allow us to launch large-scale activities.
Considering the current situation in the country, making any plans is difficult, and progressive resumption of activities will only be possible when the endemic areas are again accessible. As a first measure a number of centres for surveillance and treatment will have to be re-established, with priority given to municipalities where the majority of cases report to existing facilities. Instruction and continuous training have to be ensured, in which the newly renovated reference centre at Viana on the outskirts of Luanda will play a major role.
Mobile teams have to be re-instituted as rapidly as possible for active screening of the population in villages, again based on the number of cases reporting to stationary facilities. All of these measures, screening as well as tsetse fly control, require that the roads be cleared of landmines and repaired.
Endemic sleeping sickness is a big problem for Angola. However, the prevailing political–military situation neither adequately ensures nor allows active surveillance and treatment or vector control. In these conditions the epidemic can progress without obstacle and reach more and more individuals in the zones of transmission. Hence thousands of undiscovered and untreated patients are doomed to death. Once normality is restored in our country, the financial and human resources to reinstate efficient control programmes will have to be sought. Clearly nothing will be possible without extensive help from exterior partners.
We thank all NGOs participating in the combat against sleeping sickness in Angola: Norvegian Peoples Aid, Medicus Mundi Catalunya, Médecins sans Frontières Belgique, Médecins sans Frontières France, UCAH (United Nations Humanitarian Assistance Coordination Unit), and ECHO (European Community Humanitarian Office). We thank Dr Christian Burri for discussion and translation of the manuscript.