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246 inhabitants of Djohong, a township located in North-east Cameroon, presented with single or mixed nematode infections. They were treated by 400 mg albendazole in a single dose. The results were evaluated either with the Kato thick-smear technique and the Ritchie technique on stools and/or the Graham test: albendazole has proved to be 100% efficacious in pinworm and roundworm treatment, 63% to 84% in hookworm treatment (difference due to the type of technique used). Albendazole showed a mean efficacy in whipworm treatment (about 50% cure rate). In case of residual worm infection, the egg count is reduced from 80% to 90% which is of the utmost importance. The relative treatment failures occurring with large worm load. This systematic treatment of a whole population considerably reduces the spread of nematode eggs over the soil (18-fold for Nector americanus, 10-fold for Trichuris trichiura). This broad spectrum anthelmintic is strongly recommended in mass treatments for its efficacy and excellent tolerance, as its ovicide action reduces the probability of fecal pollution of the environment by treated patients who have residual parasites.

121 serum samples from African adults previously immunised with 17 D yellow fever vaccine alone (control group) or simultaneous yellow fever and cholera vaccines were tested for yellow fever antibodies by seroneutralization and haemagglutination inhibition assays. Comparison of the rates of seroconversion and antibody titers between the groups vaccinated the same day or into a short (less than or equal to 10 days) or a long time interval with both vaccines and the control group gave no significant difference. The association of cholera and yellow fever vaccines do not influence the long-term efficiency of yellow fever vaccination.

In 1989 there were 71 cases of imported malaria admitted to the hospital in Bordeaux. This is 16.5% and 29% lower than in 1988 and 1987 respectively, thanks to the widespread use in Africa of mefloquine chemoprophylaxis. Sub-Saharan Africa is involved in 95% of cases, mainly West Africa (70% of cases), unlike the situation in 1987, and the first cases of paludism despite mefloquine chemoprophylaxis appeared during the second semester from the seasonal mid-summer recrudescence onwards, in travellers returning from this region. The most frequent species is still Plasmodium falciparum (80% of declared cases). This imported disease especially affects young adults despite regular prophylaxis in 59% of cases. It is therefore important to recommend rigorous protection against anopheles. Male predominance (sex ratio: 5.5) was greater in 1989 than in the previous two years, and French nationals represented 85% of the population. Falciparum malaria presents symptoms in 95% of cases before the end of the month following the patient's return to France, while for P. ovale the time for symptoms to appear is between 39 days and two years after return. Management of patients on their return poses a problem of information, since in 40% of cases diagnosis is made more than a week after the first symptoms. Attacks are mild in most cases (93%); among the serious cases death occurred in a 3-year-old child. Thrombopenia is the most frequent biological sign (22.5% of cases), followed to a lesser degree by anaemia and leukopenia. Mild attacks respond well to classical treatment (halofantrine, mefloquine, quinine, chloroquine), while two cases of more complicated symptoms required exchange transfusion.

The incidence of imported malaria is increasing in France, in relation to the increasing frequency of travel to tropical areas and the extension of chemoresistant strains of Plasmodium falciparum throughout the world. Worsening morbidity and mortality due to this parasite in the last 5 years is having an impact in socioeconomic terms; this is all the more prejudicial in that a young healthy population is concerned. Traditional chemoprophylaxis is at present insufficient for adequately controlling this recrudescence. Both the public and general practitioners should be made more aware of the measures to be taken during, and especially after foreign travel, in order to reverse the present tendency concerning imported malaria, and to improve travellers' protection.

100 cases of imported malaria were registered in Hospitals of Bordeaux in 1987 and 85 in 1988. Origin of infestation is Africa in 88 p.c. of the cases mainly from Central Africa (50 p.c.) in 1987 and western Africa (67 p.c.) in 1988. The most frequent species was Plasmodium falciparum 73 p.c. in 1987 and 82 p.c. in 1988. Admitted cases in Bordeaux were mainly French (81 p.c.) with a significant male prevailing and young adults. Mean age was 29 for Europeans and 19 for the others mainly Africans. Infestation risk is in close correlation with the duration of stay in endémic zones. It is maximum for stays between 2 and 11 months. Delay for first symptoms to appear following return from an endemic zone depends of species concerned during the first month, 83 p.c. of malaria fever at Plasmodium falciparum during the second quarter, 50 p.c. of fever at Plasmodium vivax, and after one year or more 40 p.c. at Plasmodium ovale. Only 1/4 of the cases were diagnosed during the first 48 hours. Delay in diagnosing may be prolonged and is in relationship with Plasmodium falciparum chemoresistance and self-medication. 21 strains of Plasmodium falciparum were chloroquinoresistant in vitro: 1 from French Guyana, 9 from Western Africa, and 11 from Central Africa. The strain from Guyana was also less sensible to quinine with a IC 50 = 480 nmol/l.

In the coastal area of Benin, where chloroquine resistant Plasmodium falciparum strains occur, 152 children in the Guezo military camp (Cotonou) and 448 children in a fishermen village (Ekpe), on the southern bank of lake Nokoue, are examined. The falciparum malaria infected children (29 and 135 respectively) have received 35 mg/kg body weight of amodiaquine (Flavoquine) divided in three consecutive daily doses. Only one child among the 69 treated having a parasitemia higher than 1,000/mm3 failed to be cured. The amodiaquine tolerance is excellent for, respectively, 64% and 72% of the children. Minor side-effects are rapidly regressive. The frequency of conjonctival hyperhemia as an amodiaquine side-effect is nevertheless relatively high (14.7%) in the children regularly treated with this drug, e.g. those of the military camp, while it is rare (0.8%) in others, e.g. in the fishermen village children where amodiaquine is unusual as an antimalarial medicine.

Experimental studies in Bayeux, Haiti showed that the biting midge, Leptoconops bequaerti, is capable of supporting the complete development of Mansonella ozzardi but only on a very limited scale. This suggests that the species may not be involved in the natural transmission cycle despite its abundance and pestiferous nature in certain areas of Haiti. A midge-holding container is described which markedly enhanced the survival of engorged L. bequaerti in the laboratory.

A survey of 1,165 inhabitants of Bayeux, Haiti revealed that 16% were infected with Mansonella ozzardi. This was determined from a single 20 mm3 sample of finger prick blood from each individual. Amont children and young adults (< 20 years of age), fewer than 2% had detectable microfilaremias. Beyond this age the prevalence of infection for males and females was 49% and 24%, respectively. The microfilariae circulate in the peripheral blood with no significant periodicity. In general, the microfilaremias were low, with 71% of the positive cases having less than 10 microfilariae in 20 mm3 of blood; only 4% had more than 50 microfilariae. Histological examination of sectioned skin biopsies showed that the microfilariae dwell within the superficial capillary vessels; not free in the extravascular tissues.

Ultrastructural studies conducted to elucidate and compare the microanatomy of the South American (simuliid-transmitted) and the Caribbean (culicoid-transmitted) microfilariae of Mansonella ozzardi revealed that these microfilariae are essentially identical. The only difference detected was the larger central body of the Colombian microfilariae. Although the microanatomy of M. ozzardi microfilaria is essentially the same as that of other microfilariae, some of the subtle differences noted between M. ozzardi and other microfilariae include: amphids of unequal lengths, a large nucleus located approximately 30 microns from the anterior end, and an esophagus which appears to be less developed than that of Loa loa and Brugia spp. The microfilaria has a small cephalic hook, intracellular bacteriae in the hypodermal cells, and crystalloid inclusions which are most prominent in the R-1 cell and are also present in the hypodermal and esophageal cells. These crystalloids appear to be unique to M. ozzardi microfilariae.

In Haiti, positive immunofluorescent tests are observed in 5.9% of the inhabitants of a rural area in the South of the country. The index of positive reactions is increasing with age. No difference between males and females is noticed. Seropositive cases are clustered within defined families for 60% of them. The antibodies titers are low: 8 I. U. for 88% of cases. The prevalence of toxoplasmosis varies from 0 to 15%, according to the village, without any clear relationship with rainfall, altitude, or prevalence of intestinal worm infections. Subjects harboring nematodes transmitted by skin penetration are more often serologically positive than others. Oocysts voided by cats seem to be mainly responsible for transmission to humans in this part of the world.

Studies in the southern peninsula of Haiti showed that the biting midge, Culicoides barbosai, was capable of supporting the development of Mansonella ozzardi to the infective stage. The known vector, Culicoides furens, also was encountered. Both species showed distinct biting site preferences, i.e., 98% of the midges that engorged on the arms and head were C. barbosai whereas C. furens was collected mostly from the lower legs. Nine days after engorgement, 19 infective larvae were recovered from 13 C. barbosai versus six larvae from four C. furens. It was judged that C. barbosai may be as importantly involved in the natural transmission cycle as C. furens in this community.

Comparative morphological studies were conducted at the light microscope level to determine whether any difference could be detected in thin smears, thick smears, or Knott samples, between Colombian (simuliid-transmitted) and Haitian (culicoid-transmitted) Mansonella ozzardi microfilaria. Results indicated that the microfilariae from these two geographical areas are essentially identical. The small differences observed in the dimensions of microfilariae in thick and in thin smears can be attributed to different preparative procedures. The consistent morphological differences, noted in PAS-hematoxylin-stained microfilariae, from Knott smears, was that the central body was thinner and stained less intensely with the Schiff reagent in the Haitian than in the Colombian microfilariae. Although these observations suggest a physiological difference between these two forms, additional studies are needed to exclude the possibility that these differences are not indications of the age or a state of physiological activity of the microfilariae.

One hundred and twelve inhabitants of an area endemic for M. ozzardi received 20 cmm capillary blood samples by finger prick before and 30 minutes after the ingestion of 100 mg of diethylcarbamazine citrate. No significant variations in microfilaremia were detected. Thus, a provocative dose of DEC would not appear to be helpful in sampling for mansonellosis in Haiti.

Most travellers to tropical countries are young adults aged between 25 and 44; they tend to be of average or high socioeconomic status, to have a university education and to live in urban areas. The number of countries visited is high (111). Half the travellers go to Senegal, Ivory Coast and French Guiana. Asian countries are underrepresented among the clients of the Bordeaux centre because they do not require yellow-fever vaccination. The main reasons for travel are pleasure (73%) and business (23%). The length of stay is closely correlated with the reason for travel. Considerably more people travel in the winter period. The most frequently performed vaccinations are yellow fever, tetanus and poliomyelitis, in roughly equal numbers. A major role of a vaccination centre in the eyes of the public is to provide travellers with information and advice. A specialist centre of this kind, kept regularly informed about epidemiological developments around the world, is best equipped to advise on effective malaria prophylaxis. The centre's health-education role extends to all risks associated with travelling, in particular the sexually transmitted diseases and specifically tropical diseases, and also the consequences of changes in climate or altitude and failure to take general hygiene precautions. Computerized data banks accessible to the general public are certainly an information medium for the future, but at present are still underused.

The frequency of reactions to vaccinations against Yellow Fever was determined in a population of 370 travellers in good health. 25% suffered from reactions, most of which were minimal, 5% were local and 22% general of which half were of the post vaccinal viral syndrome type with multiple pains and pyrexia. Strong reactions appeared in only 8 subjects (2%). Age, sex, or number of antigens injected did not cause any significant differences.

A survey for Wuchereria bancrofti in Leogane, Haiti, revealed that 140 of 421 individuals (33%) had a patent infection, of which 40% lived in the suburban outskirts of the city. The median microfilaria density was 19.1 per 20 mm3 of blood for suburban dwellers compared with only 8.8 for those living in the city. The vector, Culex quinquefasciatus (Say), breeds mostly in and around numerous rum distilleries, located exclusively around the periphery of the city, and this undoubtedly accounts for the higher prevalence and intensity of infection among suburban dwellers.

Twelve children, 2 to 15 years of age, with falciparum malaria (parasitaemia 4,500 to 170,000/mm3) have taken 24 mg/kg body weight of halofantrine hydrochloride (Halfan) per os in three divided doses given within 12 hours. The symptomatology improved after 24 to 48 hours, with no more fever 5 to 90 hours after treatment and with a decrease of splenomegaly in 80% of the cases. The parasitic clearance was obtained after 24 to 60 hours. The haematocrit started raising again in 58% of the cases. Halofantrine hydrochloride is an efficient antimalarial drug in semi-immune patients. It is well tolerated and well accepted, thus representing an alternative for the cure of chloroquine-resistant falciparum malaria.

The authors describe a new genus and a new species of Ceratopogonidae: Baeodasymyia modesta n.g., n.sp., which somewhat resemble the two genera Paradasyhelea Macfie, 1940 and Baeohelea Wirth and Blanton, 1970.

In studies conducted between 1984 and 1986, the vector competency of Culex quinquefasciatus was assessed after bloodfeeding on 61 Haitian volunteers with different densities of Wuchereria bancrofti microfilariae (mf) and on 11 that were amicrofilaremic. Infected volunteers included persons previously given diethylcarbamazine citrate for 12 consecutive days and some that were untreated. Mosquitoes, derived from field-collected larvae, were released under bed nets and fed upon the volunteers while they slept. The mean mf uptake in mosquitoes that fed on 21 carriers with low to ultralow densities (1-28 mf/ml blood) was 0.2-4 mf/mosquito (mean = 1.7 mf). The observed infectivity rate of greater than 3,000 mosquitoes that fed on high (56-7,500 mf/ml blood; median = 525), low (11-49 mf/ml blood; median = 20), or ultralow (1-10 mf/ml blood; median = 3) density carriers was 4, 11, and 30 times higher, respectively, than the expected rate calculated from the estimated volume of the imbibed bloodmeal. These results indicate that "hidden" carriers (less than 50 mf/ml blood) may serve as a source of infection for mosquitoes, and support the increasing evidence that mosquitoes ingest more microfilariae than expected.

Economic development in Africa implies the provision of vast, sparsely populated regions with improved road networks and agricultural techniques. Climatic constraints mean that control of water resources is essential in arid areas. But hydrogrophic modifications also have the potential for adverse impact on the health of local populations. The extension of water sources and their all year round supply of water mean that people are attracted towards them, and to the same places where conditions favour the spread of intermediate hosts and vectors of parasitic diseases such as schistosomiasis, onchocerciasis, drocunculiasis and malaria. Doctor, epidemiologists, and the engineers involved in rural earth-works must therefore work together to establish systems that impede the transmission of such diseases. Examples from the Cameroon typify the need for such an approach.

Sera from individuals in an area of Haiti endemic for Mansonella ozzardi were analyzed for reactivity to antigens of Brugia pahangi, Dirofilaria immitis, Mansonella llewellyni or Ascaris lumbricoides using either an enzyme-linked immunosorbent assay or an indirect immunofluorescent antibody test. IgM and IgG reactivity to all antigens was observed with sera from both microfilaremic and amicrofilaremic individuals when compared to reactivity of sera from individuals from nonendemic areas. Antibody reactivity to B. pahangi was greater than that to other antigens. IgG reactivity of sera from endemic patients to filarial antigens was consistently greater than that of IgM. Antibody reactivity was not correlated with age or microfilarial density.

In the town of Limbe, in Haiti, 16,8% of the inhabitants show W. bancrofti microfilariae in their blood taken by finger prick between 8.00 and 10.00 p.m. From those positive patients, 208 have received a cure of DEC at the dosage of 6 mg/kg/day during ten days. The control of the therapeutic efficacity among 190 patients, after three and a half months of this cure, shows a negativity of 72%. The positives patients show a very low parasitic charge (MfD50 = 1.9). If the secondary effects are frequent (83.7%), they are often benign and temporary.

The present vector studies show that the biting midge, Culicoides furens, serves as an intermediate host for Mansonella ozzardi in Haiti. A total of 3,430 C. furens were collected as they engorged on infected individuals. Under the maintenance conditions described herein, the microfilaria required 9 days to reach the infective stage. Approximately 43% of the midges survived, and from these 1,128 infective stage larvae were collected. This represents an overall infection rate of 0.76 larva per midge. Typically, there was a directly proportional relationship between the infection rate in midges and the level of microfilaremia in the individuals upon whom the C. furens fed. Also, the vector efficiency of C. furens collected from saltwater or freshwater breeding habitats was comparable.

Results of the numbering of T. trichiura, A. lumbricoides et N. americanus eggs found in the stool, taken from a representative sample of the population of Tortuga island, shows the importance of parasital load borne by people attacked by the parasites. Those who produce the greatest number of eggs for a gram of faeces are young children. For adults, the evolution of the parasital load follow that of the prevalence, for each Nematodes, with an increase of the average number of eggs of A. lumbricoides per gram of faeces for adults aged 30 to 44, and of the average number of N. amercanus per gram of faeces for adults aged 45 to 59. Moreover women adults show a higher number of parasites than men. Farmers from villages within the interior of the island who are more often attacked than those from the coast, also bear a parasital load which is twice as high. Victims less than 5 years old and more than 30, particularly women, whose faeces are richest in eggs, seem to present the greatest danger for the transmission of ascaridiosis and necatorosis in Toruga Island.

Sixty-nine of 83 (83%) patients with circulating microfilariae of nocturnally periodic Wuchereria bancrofti were detected in daytime blood films following the one-time administration of diethylcarbamazine at a dose per patient of 1 +/- .25 mg/kg of body weight. This method of detecting microfilaria carriers in Haiti is recommended as a reasonably sensitive alternative when circumstances make it impossible to conduct a nighttime blood survey.

Wuchereria bancrofti persists in Haiti in localized foci, discontinuously distributed. The parasite, transmitted by Culex quinquefasciatus, develops in mesoendemic or hyperendemic fashion in urban and suburban areas, on the coastal plains sheltered from the prevailing winds, predominantly in the Nord department and around the gulf of La Gonave. Lymphatic filariasis is a major public health problem. Its impact is more evident in males on account of the genital repercussion of the disease. The acute lesions appear from early infancy and are related to microfilarial density. The chronic lesions begin with adolescence, and occur with high frequency in adults. Lymphatic filariasis has retreated in the countries where socioeconomic or sanitary conditions have improved: Puerto Rico, French West Indies, Cuba. In countries confronted by underdevelopment, overpopulation and uncontrolled urbanization, the disease is prevalent: Haiti, Dominican Republic, Trinidad. It is essential to carry out epidemiological investigations in order to identify the extend of the lymphatic filariasis problem in the Caribbean, particularly as population migration in both directions is becoming intensified: the native people looking for work in the industrialized countries, and tourists seeking the attractions of the tropics.

Biomphalaria glabrata, an intermediate host for Schistosoma mansoni, was first reported in Haiti in 1891 at one location in the Départment du Nord and in 1977 it was reported at several sites in one additional watershed. Our study identifies two additional locations each on a different watershed plus a third possible site. A wide but discontinuous distribution of the snail on the north coast of Haiti is confirmed (no autochthonous infections with S. mansoni have been reported). While there are many possible explanations for this discontinuous distribution, a role for the competitor Thiara granifera in shaping the current distribution of B. glabrata is suggested. The incursion of B. glabrata into Haiti is not recent but at the same time is not expanding.

The clinical evaluation of 150 individuals in Bayeux, Haiti, revealed no significant morbidity that could be attributed to infection with Mansonella ozzardi. However, the distribution of patent infections and their microfilaria density were significantly affected by the age and sex of the individuals. Also, the eosinophilic response was associated with the intensity of the microfilaremia when age was considered as a co-variable. The microfilaria rate was significantly higher in certain occupations, but this was discounted as a risk factor for reasons that are explained.

A survey for Wuchereria bancrofti in Limbe, Haiti (est. pop. = 10,500) revealed that 17% (231/1,450) had a patent infection. Nearly half of those surveyed harbored fewer than 10 microfilariae (mf) per 20 mm3 of finger-prick blood; the median mf density for females and males was 12.4 and 9.5, respectively. Parasitemias occurred as early as age 4. Antibody titers greater than or equal to 1:20 against adult D. viteae antigen were observed in 38% of microfilaremic individuals and in 29% of amicrofilaremic individuals. Peak antibody responsiveness (40%) was observed between 5 and 9 years of age. In all age groups there was no correlation between mf density and antibody titer. Among the mf carriers, 5.6% had no clinical symptoms. Lymphangitis was a common feature with 14.3% having lymphedema, 8.2% with edema of the lower extremities, and 1.3% reporting episodes of chyluria. Genital involvement among women was rare, but in males 5.4% had genital swelling and 4.5% had hydroceles. Culex pipiens quinquefasciatus (Say) was observed to support the complete development of W. bancrofti in Limbe.

An epidemiological survey is conducted by spot-checks over about 10% of the population of Tortuga Island in order to estimate the prevalence of intestinal helminthiasis in that region of the Republic of Haïti, by researching the presence of eggs in faeces. Population sample is representative of the whole of the island's population excepting the 0-4 years old group whose faeces are difficult to obtain. Faeces are examined through the Kato method, a very simple, quick and remarkably accurate procedure. Trichuriasis and ascariasis, which are transmitted in the area around the house, affect mainly children, but also adults. Women seem to be more often infested than men by Ascaris lumbricoides. Necatoriasis, the farmer's disease, hits primarily young men and elderly women who spend most time in the fields. It is observed in inland villages where people are engaged in agricultural production, with a higher incidence if they are located in a not so sloping zone.

A study to compare the sensitivity of four sampling methods in detecting Mansonella ozzardi among 133 inhabitants of Bayeux, Haiti, is reported. The Knott method proved the most sensitive with 40 microfilaria carriers detected. No additional infections were revealed by the other sampling methods. This was followed in order by 20 mm3 thick films of earlobe blood (34 cases), finger-prick blood (32 cases in the first sample), and skin biopsy (14 cases from paired samples). The combination of three finger-prick samples (60 mm3 of blood) detected 38 of 40 (95%) Knott-positive infections. The Knott method detected only one case not observed by at least one of the other three sampling methods. This sampling procedure did not detect more M. ozzardi in the 0-19-year age group than observed by the 20-mm3 finger prick method. Based on these results, a correction factor of 1.25 can be applied to our earlier Bayeux survey.

A death from chloroquinoresistant falciparum malaria contracted by a traveller under chloroquine chemoprophylaxis during a stay in the Cameroon provides the authors with an opportunity to analyze the extension of chloroquinoresistance in Africa. Having appeared there about 10 years ago, it remained for a long time localized in East Africa. In recent years, it has moved West. Today, 17 countries located from the North to the South between Sudan and Mozambique, and from East to West between Kenya and the Cameroon are affected, as are the Malagasy Republic, the Comores and Zanzibar. The strains resistant to chloroquine are still sensitive to amodiaquine. In certain regions which are widespread in the continent, resistance to pyrimethamine has become evident in the last 30 years; resistance to pyrimethamine-sulfadoxine and pyrimethamine-dapsone has appeared in the last 3 years in East Africa. In the light of the complexity of the problem of malaria chemoprophylaxis, the authors emphasize the necessity of resensitizing the public at large with respect to personal protection against biting anopheline mosquitos, especially during the hours of darkness. The medical profession should equally be made aware of these new problems. Three types of chemoprophylaxis in relation to the areas visited are proposed: the first for West Africa; the second for Central Africa, neighbouring regions and the Malagasy Republic and the Comores; the third for the 3 East Africa countries the most affected, which are Kenya, Burundi and Tanzania.