Seasonal migration: a risk factor for HIV infection in rural Senegal.

Sociodemographic and epidemiological data collected on a rural population of the Ziguinchor region of Senegal showed that a large part of the adult population, 80% of women between 15 and 24 years old and 82% of men between 20 and 40 years old, move each year on seasonal labor migrations to the main cities of Senegal or the Gambia or their proximity. In October 1990, an exhaustive seroprevalence survey of the population aged 20 years or older (3,230 persons tested) showed that 0.8% was HIV-2 and 0.1% HIV-1 seropositive. Interviews of 91 persons (24 seropositive persons and 67 seronegative controls) revealed that seropositivity was associated with a history of blood transfusions, injections, sexually transmitted diseases, and seasonal migration. Our findings suggest that in the rural area under study, beside a few cases of transmission by blood transfusion or injection, HIV-2 and HIV-1 are mainly transmitted first to adult men through sexual contacts with infected women met during their seasonal migration and second to their wives or regular partners once they are back home.

HIV-2 and HIV-1 AIDS cases in Senegal: clinical patterns and immunological perturbations.

The serological and immunological parameters, disease patterns, and social characteristics of 39 human immunodeficiency virus type 2 (HIV-2) seropositive CDCIV cases seen in Dakar, Senegal were studied. These data were compared with those obtained from 48 HIV-1 seropositive CDC stage IV patients. Social characteristics of populations infected with HIV-1 or HIV-2 were clearly different. A patient sex ratio of three men to one woman was found for both viruses. In addition, the immune status of nonsymptomatic HIV-1 and HIV-2 seropositive people was evaluated. The correlation between abnormalities of the immune system and clinical status was similar for the two infections. Clinical symptoms of both diseases were the same, but this cross-sectional study could not address the questions of differences between the two infections in latency and development of disease or specific manifestations of HIV-2 infection. This study suggests that HIV-2 infection may contribute to the present AIDS epidemic in West Africa.

Haemorrhagic fevers and ecological perturbations.

Hemorrhagic fever is a clinical and imprecise definition for several different diseases. Their main common point is to be zoonoses. These diseases are due to several viruses which belong to different families. The Flaviviridae have been known for the longest time. They include the Amaril virus that causes yellow fever and is transported by mosquitoes. Viruses that have come to light more recently belong to three other families: Arenaviridae, Bunyaviridae, and Filoviridae. They are transmitted by rodents (hantaviruses and arenaviruses) or from unknown reservoirs (Ebola Marburg). The primary cause of most outbreaks of hemorrhagic fever viruses is ecological disruption resulting from human activities. The expansion of the world population perturbs ecosystems that were stable a few decades ago and facilitates contacts with animals carrying viruses pathogenic to humans. Another dangerous human activity is the development of hospitals with poor medical hygiene. Lassa, Crimean-Congo or Ebola outbreaks are mainly nosocomial. There are also natural environmental changes: the emergence of Sin Nombre in the U.S. resulted from heavier than usual rain and snow during spring 1993 in the Four Corners. Biological industries also present risks. In 1967, collection of organs from monkeys allowed the discovery in Marburg of a new family of viruses, the Filoviridae. Hemorrhagic fever viruses are cause for worry, and the avenues to reduce their toll are still limited.

HIV1 and HIV2: two ancient viruses for a new disease?

PIP: The availability of serum specimens collected in 1965 in a rural region of the Ivory Coast for a serosurvey of infection with rickets and arbovirus led to the findings that human immunodeficiency viruses (HIV) 1 and 2 have a long history. The sera were screened for antibodies to HIV 1 and 2 through enzyme-linked immunosorbent assays, and positive findings were confirmed by Western blot. Of the 349 sera analyzed, 9 were positive only for HIV 1, 3 were positive only for HIV 2, and 15 were positive for both HIV 1 and 2. When Western blot analysis was performed, 13 sera recognized only some gag-coded proteins (especially P25 and 55) on HIV 1 blots without any reaction to HIV 2 antibodies. 2 contained antibodies against env-, gag-, and pol-coded proteins; 1 on an HIV 2 blot form 1965 and 1 on both viruses in the 1969 batch. These findings indicate that 2 people were infected with HIV 2 during the 1960s and 13 (3.7%) had antibodies against an infectious agent that shared epitopes with HIV 1 gag-coded proteins but not HIV 2.^ieng

Serological evidence in sheep suggesting phlebovirus circulation in a Rift Valley fever enzootic area in Burkina Faso.

Within the Phlebovirus serogroup, Rift Valley fever (RVF) virus is endemo-enzootic in the African sahelian zone. Recently an RVF epizootic in West Africa prompted a serosurvey in the major sheep and cattle raising areas. Because of the close antigenic relationship between the phleboviruses it appeared of interest to evaluate the prevalence of the other phleboviruses also. In 1987, 482 sheep serum samples were collected in 2 different ecological zones of Burkina Faso and tested for the presence of phlebovirus antibodies. A sensitive but non-specific immunofluorescent antibody test and a specific enzyme-linked immunosorbent assay (ELISA) were used, with the following African phlebovirus antigens: Rift Valley fever (RVF), Arumowot, Gabek Forest, Gordil, Saint Floris and Odrenisrou. A total of 15.8% of the sera sampled had anti-RVF antibody in the ELISA. RVF virus appeared to be more active in drier areas such as the sahelian region, known to be an enzootic area for the disease. Antibodies to other phleboviruses were found in 11.8% of the samples, independent of RVF virus activity. It is assumed that sheep can be infected by different phleboviruses.

Emerging viruses.

Hemorrhagic fever viruses are among the most dangerous biological agents known. New ones are discovered every year, and artificial as well as natural environmental changes are favoring their spread.

[Toxoplasmosis in the Republic of Senegal. Sero-epidemiological survey]. / Toxoplasmose en république du Sénégal. Sondage séro-épidémiologique.

The presence of Toxoplasmosis in Senegal was investigated by the detection of IgG antibodies. 415 samples were obtained from healthy subjects from different regions of the country. In subjects of over 30, a greater number were found positive for IgG antibodies if they lived in a humid climate (25% in Northern Senegal, 57.7% in eastern Senegal). In Dakar 33.3% of the pregnant women studied had antibodies. This study confirms the presence of Toxoplasmosis in Senegal.

[Serologic screening of certain zoonoses in the abattoir personnel in Djibouti]. / Dépistage sérologique de certaines zoonoses sur le personnel de l'abattoir de Djibouti-ville.

A sero-prevalence survey was carried out on 108 workers of Djibouti slaughter-house in order to search out the carriers of agents of zoonotic diseases. The sera revealed prevalences of 6.5% for brucellosis, 0.9% for chlamydiosis and 42.6% for toxoplasmosis whereas no positive reactions were detected for Rift valley fever, Crimean Congo hemorrhagic fever, hydatidosis, and toxocarosis. These data are compared with results obtained from cattle and small ruminants slaughtered in Djibouti.

[Surveillance of the circulation of arbovirus of medical interest in the region of eastern Senegal]. / Surveillance de la circulation des arbovirus d'intérêt médical dans la région du Sénégal oriental (1988-1991).

A study about the circulation of arboviruses of medical interest in southeastern Senegal was conducted from 1988 to 1991, during and around the periods of transmission. Specific IgM antibodies were detected by ELISA test in human sera, as a sign of a recent infection within 2 to 5 months. The comparison of the serological IgM results from human surveys in different villages, and the isolations of arboviruses from mosquitoes during the same period of time permitted a rapid and global evaluation of the circulation of these viruses. A low level of yellow fever virus activity was detected both in humans and mosquitoes in 1988 to 1990. A dengue 2 epizootic occurred in 1989-1990. Dengue 2 virus was isolated from humans and mosquitoes in 1990. Some dengue 2 outbreak may occur in the upcoming years. A Zika virus epizootic outbreak was observed each year. A human strain was isolated in 1990. The other flaviviruses (West-Nile, Kedougou, Wesselsbron), Chikungunya virus, Rift Valley Fever virus and Crimean-Congo Hemorrhagic Fever virus did not seem to present a major public health concern in southeastern Senegal.

[Pulmonary tuberculosis and HIV seropositivity at the Principal Hospital of Dakar (Senegal)]. / Tuberculose pulmonaire et séropositivité HIV à l'hôpital principal de Dakar (Sénégal).

In a prospective survey conducted in 1990 in the Principal Hospital of Dakar, pulmonary tuberculosis was 2.3 times more frequent in HIV seropositive patients (12.5%) than in HIV seronegative patients. We studied 22 cases of pulmonary tuberculosis in HIV+ patients and compared them with a control group of HIV- patients admitted for pulmonary tuberculosis. Tuberculosis occurred in 6 out of 22 asymptomatic HIV+ patients, in 15 out of 22 patients with clinical AIDS and in 1 patient with ARC syndrome. Clinical signs were the same as in controls, except for patients with advanced AIDS who developed cardinal signs. TB intra-dermal reactions were more often negative in HIV+ patients, notably those with HDV1, expressing immunodepression. Radiological images were typical in 81% of patients and in 86% of controls. However, concomitant infections were common in both groups, with atypical radiology and hyperleukocytosis. At light microscopy, there was no difference in the frequency of acid and alcohol fast bacilli between the two groups. The mortality rate was increased in HIV+ patients, but this was not due to tuberculosis. Relapses were frequent in both groups, due to poor compliance with treatment.

[Viral hemorrhagic fevers: what is the risk for travelers?]. / Les fièvres hémorragiques virales: quel risque pour le voyageur?

The term hemorrhagic fever covers a number of diseases with different clinical and epidemiologic features. All these diseases are zoonoses but their occurrence is not confined to tropical areas. Some occur in polar zones. Travelers to endemic areas for these diseases are at risk of infection. There are two modes of transmission. Arthropods are vectors for some diseases such as yellow fever, dengue fever, and Rift Valley fever which are carried by mosquitos and Congo-Crimea virus which is carried by ticks. Airborne contamination by rodent excrement is responsible for transmission of hantaviruses and arenaviruses. Nosocomial infection is a risk for health care providers. Some types of hemorrhagic fever such as Bolivian hemorrhagic fever are highly localized, while other types such as dengue are observed worldwide. Judging from the small number of cases observed in European countries, the overall risk for travelers seems low except unless high-risk activities are planned. The main exceptions are yellow fever and dengue which can easily be transmitted to tourists by mosquitos. Yellow fever can be prevented by vaccination. Typical dengue is usually self-limited but hemorrhagic forms require treatment to prevent shock.

[West Nile viral meningo-encephalitis in Tunisia]. / Méningo-encéphalite à arbovirus West Nile en Tunisie.

In autumn 1997 an epidemic outbreak of meningoencephalitis was observed in two coastal districts of Tunisia. A total of 173 cases were recorded with 8 deaths. Detection with IgM capture and indirect IgG ELISAs demonstrated West Nile virus infection in 86% of patients from whom specimens were collected. West Nile is endemic in Asia and Sub-Saharan Africa. Epidemics in humans and horses have also been reported in the Mediterranean region and southern European countries. However this is the first report in Tunisia. Special West Nile virus surveillance is necessary especially in countries at high-risk for repeated introduction of this arbovirus.

[Pathologies associated with HTLV-1 virus in Dakar (1992-1995)]. / Pathologies associées au virus HTLV-1 à Dakar (1992-1995).

A clinical and laboratory study was conducted in Dakar (Senegal) to assess the involvement of HTLV-1 virus (human T lymphotrophic virus type 1) in various diseases. Patients were enrolled at three locations: the Dermatology Department of the Fann University Hospital Center (845 patients) from 1992 to 1995, the Dermatology Department of the Le Dantec University Hospital Center and the Oncology Department of the Principal Hospital (7 patients) in 1994 and 1995. The incidence of involvement of human retroviruses in neurologic complications seemed low (HTLV-1: 2%, HIV: 3%) and only 6 cases of tropical spastic paraparesis associated with specific anti-HTLV-1 antibodies were diagnosed in 3 men and 3 women with a mean age of 51 years. These cases which were identical to those previously described cases in the West Indies and Japan confirms the existence of this disease in Senegal. In addition 3 cases of isolated facial paralysis were observed in HIV positive patients. Combined HIV/HTLV-1 infection was observed in 3 cases and was not associated with special clinical findings. Adult T-cell leukemia/lymphoma (ATL) was detected in 4 patients including leukemia with proliferation of CD4 and CD25 in two cases and lymphoma in one case. In one case of ATL two proviruses were identified in circulating tumor cells. These are the first cases of ATL to be reported in Senegal. Molecular characterization of part of the envelope gene (gp 21) from patients with PST hospitalized in a neurology ward showed that the virus present in Senegal belonged to the universal HTLV-1 A type. This study indicates that two types of diseases are associated with HTLV-1 infection in Senegal. Further epidemiologic studies will be needed to evaluate the incidence of the virus and of the diseases associated with it. Prevention will depend partly on screening blood donors as has now been started at the Blood Transfusion Center of Dakar.

[Hantavirus and pulmonary pathology]. / Hantavirus et pathologie pulmonaire.

The hantavirus pulmonary syndrome recognized in the United States in 1993 quickly brought the formerly little known virus into the limelight. Contrary to what has been written almost everywhere, this is not a "new" virus causing new "emerging" disease. Hantaviruses have been harbored in their natural hosts, three subfamilies of murine rodents, for millions of years. The phylogenetic classifications of these viruses follows that of their hosts, proving close adaptation and contradicting short-term emergence of American serotypes in Eurasia. Certain hantaviruses are the causal agents of renal diseases of variable severity grouped together under the term of hemorrhagic fever with a renal syndrome in Eurasia. Others cause acute respiratory distress syndrome, particularly in North America. Most cases occur in adults and the sex-ratio always favors men, probably due to exposure to airborne rodent ejections. No interhuman contamination is observed. A few dozen cases of hantavirus pulmonary syndrome are reported annually in North America and a few hundred cases in Europe. China is the only country were incidence has been high enough for hundreds of years to lead to an experimentation on vaccines. Hantaviruses are difficult to isolate and diagnosis in humans is based on serology. Improved diagnostic tools have led to a better assessment of the impact of this virus on public health. An epidemic in France in 1996 caused 230 cases while only 808 cases had been registered since 1977. Most of the cases occurred in Northeastern France and were focalized.

[Transmission of HIV-2 virus in a rural area of Senegal]. / Circulation du virus HIV 2 en zone rurale au Sénégal.

Various investigations into the prevalence of HIV2 infection undertaken on samples of senegalese rural populations from Casamance, Eastern Senegal, the Thies Region and the Ferlo Region, show a gradient from south to north. Levels vary from 0.9% (western Casamance) to 0% (Ferlo). These results led to a detailed investigation being undertaken in a Casamance village, paralleled by questioning reference cases to define risks associated with HIV2 seropositivity. Prevalence in this village is 0.82%, and all age groups are affected. HIV2 disrupts the immune system before clinical symptoms appear. 10% of the seropositives can be classed as CDCIV.