Longitudinal study assessing the return of chloroquine susceptibility of Plasmodium falciparum in isolates from travellers returning from West and Central Africa, 2000-2011

Background

Chloroquine (CQ) was the main malaria therapy worldwide from the 1940s until the 1990s. Following the emergence of CQ-resistant Plasmodium falciparum, most African countries discontinued the use of CQ, and now promote artemisinin-based combination therapy as the first-line treatment. This change was generally initiated during the last decade in West and Central Africa. The aim of this study is to describe the changes in CQ susceptibility in this African region, using travellers returning from this region as a sentinel system.

Methods

The study was conducted by the Malaria National Reference Centre, France. The database collated the pfcrtK76T molecular marker for CQ susceptibility and the in vitro response to CQ of parasites from travellers’ isolates returning from Senegal, Mali, Ivory Coast or Cameroon. As a proxy of drug pressure, data regarding CQ intake in febrile children were collated for the study period. Logistic regression models were used to detect trends in the proportions of CQ resistant isolates.

Results

A total of 2874 parasite isolates were genotyped between 2000–2011. The prevalence of the pfcrt76T mutant genotype significantly decreased for Senegal (from 78% to 47%), Ivory Coast (from 63% to 37%), Cameroon (from 90% to 59%) and remained stable for Mali. The geometric mean of the 50% inhibitory concentration (IC₅₀) of CQ in vitro susceptibility and the proportion of resistant isolates (defining resistance as an IC50 value > 100 nM) significantly decreased for Senegal (from 86 nM (59%) to 39 nM (25%)), Mali (from 84 nM (50%) to 51 nM (31%)), Ivory Coast (from 75 nM (59%) to 29 nM (16%)) and Cameroon (from 181 nM (75%) to 51 nM (37%)). Both analyses (molecular and in vitro susceptibility) were performed for the 2004–2011 period, after the four countries had officially discontinued CQ and showed an accelerated decline of the resistant isolates for the four countries. Meanwhile, CQ use among children significantly deceased in this region (fixed effects slope = −0.3, p < 10^-3).

Conclusions

An increase in CQ susceptibility following official withdrawal of the drug was observed in travellers returning from West and Central African countries. The same trends were observed for molecular and in vitro analysis between 2004-2011and they correlated to the decrease of the drug pressure.

Outbreak of epidemic typhus associated with trench fever in Burundi

BACKGROUND

After a 12-year absence, epidemic typhus has re-emerged among the displaced population of Burundi. Following the outbreak of civil war in 1993, over 760000 people now inhabit refugee camps, under appalling conditions. A typhus outbreak occurred among prisoners in a jail in N'Gozi in 1995. At the time, the disease was not recognised, and was referred to as sutama. Reports of sutama among the civilian population date back to late 1995 and, in association with body-louse infestation, the disease has subsequently swept across the higher and colder regions of the country.

METHODS

During a field study in February, 1997, 102 refugees with sutama underwent clinical examination and interview. Serum samples were collected and infesting body lice removed. Microbiological analysis included antibody estimations and specific PCRs aimed at diagnosis of Rickettsia prowezekii, Bartonella quintana, and Borrelia recurrentis. Between January and September, 1997, nationwide epidemiological data on the prevalence and distribution of sutama was obtained through liaison with local health services. A second field study in March, 1997, entailed the collection of further serum samples from suspected cases of sutama in different regions of Burundi.

FINDINGS

Most of the 102 patients with sutama during initial assessment presented with manifestations similar to those previously described for typhus in Africa, though skin eruptions occurred in only 25 (25%) cases. Microbiological testing revealed evidence of R prowazeki infection in 76 (75%) patients, confirming that most cases of clinically-diagnosed sutama were epidemic typhus, and supporting the reliability of clinical diagnosis as a basis for the nationwide surveillance of the disease. Up to September, 1997, 45558 typhus cases were clinically diagnosed, most of which occurred in regions at an altitude of over 1500 m. Serological testing of 232 individuals from different regions of Burundi provided microbiological evidence to support clinical diagnoses in seven provinces, confirming the widespread nature of the outbreak. Serum from 13 of the original 102 patients and 19 (8%) of the 232 suspected cases had raised antibody titres against B quintana. A fatality rate of 15% among jail inmates fell to 0.5% after administration of a single dose of 200 mg doxycycline to suspected cases.

INTERPRETATION

A gigantic outbreak of R prowazekii-induced typhus and B quintana-induced trench fever is continuing in Burundi. Transmission of both diseases to such a large number of people has followed a widespread epidemic of body-louse infestation. Diagnosis of typhus could be reliably made by means of clinical criteria, and the disease could be efficiently and easily treated by antibiotics. This epidemic highlights the appalling conditions in central-African refugee camps and the failure of public-health programmes to serve their inhabitants. Louse-associated disease remains a major health threat in this and other war-torn regions of the world.

Prevalence of antibodies to Coxiella burnetti, Rickettsia conorii, and Rickettsia typhi in seven African countries

The prevalences of antibodies reactive with Coxiella burnetti, Rickettsia conorii, and Rickettsia typhi were determined by indirect fluorescent antibody testing of sera from seven African countries. The seroprevalences of antibodies reactive with C. burnetti and R. conorii in countries from North Africa were similar to those reported from southern Europe. In countries of sub-Saharan Africa, the seroprevalence of antibodies reactive with C. burnetti varied greatly; the generally higher figures for West Africa, where stock breeding is prominent, suggested that domestic animals might be the main reservoirs of infection. The prevalence of antibodies to the recently described species Rickettsia africae was higher than that reported for spotted fever-group rickettsiae from elsewhere in the world and paralleled the distribution of Amblyomma species. Western blot results suggested that the antibodies detected were more likely to be reactive with R. africae than with R. conorii, the main vector of which (Rhipicephalus species) rarely feeds on humans. The seroprevalences of antibodies reactive with R. typhi were higher in coastal regions, where Rattus norvegicus--the natural host of the vector Xenopsylla--is more prevalent, than in inland areas.

[Apropos of 2 cases of severe malaria contracted in the port of Marseille]

Acute Plasmodium falciparum malaria occurred during summer 1993 in two inhabitants living close to Marseille harbour. History of blood transfusion and travel outside France were excluded as was also discarded airport malaria. Entomological investigations confirmed the absence of Anopheles breeding sites in the port area. An hypothesis is a vectorial transmission following introduction of one or several anopheles arrived on a ship coming from tropical Africa. During this season, the weather conditions were favourable to the survival of anopheles and the completion of P. falciparum sporogonic cycle. Physicians were advised to take into consideration malaria in the differential diagnosis of fever from unknown origin in any patient working or living inside or around the harbour area regardless history of previous travel in malaria endemic region.

Serologic evidence for human ehrlichiosis in Africa

Human ehrlichiosis is a recently recognized rickettsial disease. It is caused by Ehrlichia chaffeensis, an intraleucocytic Gram-negative, obligate intracellular bacterium, grouped within the genus Ehrlichiae. Most human cases of ehrlichiosis have been diagnosed in the USA. Two cases have been reported outside of the USA, one in Europe and one in Africa. From 1 January to 30 June 1992, 765 sera from blood donors or other asymptomatic subjects in 8 African countries, including Ivory Coast, Burkina Faso, Mali, Central African Republic, Angola, Zimbabwe, Mozambique and Commores Islands, were tested by indirect immunofluorescence for the presence of E. chaffeensis antibodies. Positive sera were confirmed by Western immunoblotting. Only two of 765 sera tested were positive. One serum obtained from Burkina Faso had an IgG titer of 1:200 and one from Mozambique had an IgG titer of 1:80. Human ehrlichiosis seems to occur infrequently in Africa, although many more sera from additional African countries need to be evaluated.

Evidence of subjects sensitized to Leishmania infantum on the French Mediterranean coast: differences in gamma interferon production between this population and visceral leishmaniasis patients

The Marseilles region is an endemic area for visceral mediterranean leishmaniasis, but although the number of dog cases, the parasite's main host, is very high, only a few people develop the disease. We looked for sensitized healthy subjects among 25 healthy individuals living in this area by studying their in vitro lymphoproliferative response to Leishmania infantum antigens and gamma interferon synthesis. We found that 65% of tested subjects were sensitized against L. infantum. We compared their cell mediated immunity to that of 13 active Kala-Azar patients and 13 controls from non-endemic areas. In patients, results showed a specific cellular immuno-deficiency in the lymphocyte response to L. infantum antigens and a global deficiency of gamma interferon production. Interestingly, the healthy individuals from the endemic area who responded to L. infantum antigens were found to produce high gamma interferon levels after L. infantum antigen stimulation. After healing, the cell mediated-immunity of the 3 patients we followed up was similar to that of the sensitized tested healthy subjects, but the former were still producing antibodies at the time of study.

[Prevention of malaria in travellers and expatriates]

Since the occurrence of the chloroquino-resistance, chemoprophylaxis for all is not anymore the sound principle to malaria prophylaxis for travellers and expatriates. Protection against malaria has now to be based on comprehensive actions (chemoprophylaxis, control of infecting bites, treatment of malaria cases as soon as first symptom occur), they have to be combined, as a whole or not, according to the area, the duration and the type of tropical stay, and even sometimes according to some parameters peculiar to an individual. The development of concepts concerning the epidemiology of human malaria and the use of antimalarial drugs, either as protective or curative, lead more and more to the necessity for any traveller or expatriate to take medical advice from a specialized physician.

[Anti-malaria chemical prophylaxis in Europeans and anti-Plasmodium fluorescence antibodies]

The authors recorded clinical histories and tested serum for the presence of malaria fluorescent antibodies in 160 healthy Europeans who had been living for more than 4 weeks in West or Central Africa. Malaria or fever of unknown origin occurred in 37 of 50 subjects who were careless about taking prophylactic drugs while abroad. Out of 110 people regularly taking suppressive amino-4-quinoline therapy, 21 had presented febrile attacks but serological tests were only positive in 8 cases. Positive serological reactions at low titers were obtained in 3 subjects with no history of past infection and who had faithfully taken suppressive medications. These results confirm the value of the malaria immunofluorescence test for the detection of occult malaria in blood donors outside endemic areas, and explain the necessity to consider previous regular, irregular or absent chemoprophylaxis before interpreting the serological results of a febrile patient returning from overseas.

[Syndrome of inappropriate secretion of vasopressin. Apropos of 3 cases]

3 cases of inappropriate vasopressin secretion during one case of anaplastic carcinoma of the lung, one case of carcinoma of the prostate with bony metastases and one case of acute intermittent porphyria are presented. The plasma levels of vasopressin, measured by radioimmunoassay were high. Treatment with demeclocycline was attempted in one case. The clearance of free water was positive but the treatment was poorly tolerated by the digestive tract.

[Trial serologic detection of Plasmodium carriers among blood donors of the Centre de Transfusion Sanguine de Marseiile]

This paper is a survey of possible reservoir hosts of Plasmodium among donors of the blood transfusion Center of Marseille, by IFA test with P. falciparum and P. cynomolgi bastianellii antigens. It was found 15,7 per cent of positivity among 644 sera carefully selected during 6 months. Nord Africa and West Africa were the most dangerous countries, the former because of the great number of donors (332 of 744), the later because of the high rate (15,8 per cent) of positivity. The incidence of the say (frequency and long time) in infested countries and the interval from tate (15,8 per cent) of positivity. The incidence of the stay (frequency and long time) in infested countries and the interval from the last infestation possibility to the IFA test are very important factors. A prevention scheme is proposed: The donors staying during a very long time in infested countries will generally be used only for preparing plasma fractions by ethanol precipitations. For the others donors the blood will be used for preparing whole blood, red cells, fresh or frozen plasma, platelets and leucocytes preparation, in which a few parasites can be present, inly if a IFA test is negative 4 months after their coming back in our country.