Malaria chemoprophylaxis for the traveler

Pre-Exposure Chemoprophylaxis (PREP) as an HIV Prevention Strategy

Chemoprophylaxis may be a prevention strategy for the sexual transmission of human immunodeficiency virus (HIV). Evidence suggests that condom use has waned with the availability of antiretroviral medication, at least in some resource-rich settings. Barrier methods of HIV prevention have inherent problems, and the potential for failure. Microbicide research has focused primarily on male-to-female transmission. Analogous to post-exposure prophylaxis, HIV prevention may be achieved by pre-exposure prophylaxis in some settings. Research in this potential strategy may be rewarding.

Fatal Intoxications Due to Administration of Isosorbide Tablets Contaminated with Pyrimethamine

In January 2012, 664 cases of pyrimethamine toxicity and 151 deaths were reported among cardiac patients that had recently received free medicines from pharmacy of Punjab Institute of Cardiology, Lahore, Pakistan. These patients, ages ranged from 58 to 75 years, were prescribed simvastatin, clopidogrel, aspirin soluble, isosorbide mononitrate, and amlodipine. On examination of medications being given to them, it was found that a particular batch of isosorbide mononitrate tablets was contaminated with 50 mg pyrimethamine. Cardiac patients were taking isosorbide contaminated with pyrimethamine twice daily (100 mg pyrimethamine/day), whereas therapeutic dose of pyrimethamine for malaria is 25 mg/week. Postmortem urine, cardiac blood, and femoral blood specimens of three deceased males were submitted to author's laboratory for analysis. Postmortem toxicological analysis revealed that pyrimethamine concentration fell within the range of 1-10 μg/mL by liquid chromatography. Clinical, autopsy, histopathological, and toxicological findings strongly suggested toxicity due to pyrimethamine accumulation that resulted in deaths of these cardiac patients.

An outbreak of pyrimethamine toxicity in patients with ischaemic heart disease in Pakistan

We investigated an outbreak of darkening of skin, bleeding from multiple sites, leucopenia and thrombocytopenia in ischaemic heart disease patients. Case patients were defined as patients who had received medicines from the pharmacy of Punjab Institute of Cardiology between 1 December 2011 and 12 January 2012 and who developed any one of the following: darkening of skin, bleeding from any site, thrombocytopenia and leucopenia. Clinical and drug-related data were abstracted. All 664 case patients had received iso-sorbide-mono-nitrate contaminated with about 50 mg of pyrimethamine, and 151 (23%) died. The median age of 117 patients admitted at Jinnah Hospital Lahore was 57 years (range, 37-100) and 92 (79%) were male. The median time from intake of medicine to presentation was 37 days (range 13-72). Symptoms and signs included bleeding (in 95% of the patients), skin hyperpigmentation (in 61%), diarrhoea (in 53%) and abdominal pain (in 48%). At presentation, the median white cell count was 2.3 × 10(9) /L (range, 0.1 × 10(9) -16.0 × 10(9) ), the median hemoglobin concentration was 109 g/L (range 58-169) and the median platelet count was 18 × 10(9) /L (range, 0 × 10(9) -318 × 10(9) ). Bone marrow examination revealed trileneage dysplasia and severe megaloblastosis. The predictors of mortality included presentation prior to 15 January 2012, age more than 57 years, hypotension and leukocyte count less than 1.5 × 10(9) /L. None of the patients who died received Calcium folinate because all deaths occurred prior to contaminant identification. We describe an outbreak of pyrimethamine toxicity in ischaemic heart disease patients receiving medicines from a single pharmacy due to accidental contamination of iso-sorbide mono-nitrate tablets at industrial level. Late recognition of illness resulted in high mortality.

Epidemiology of malaria presenting at British Columbia's Children's Hospital, 1984-2001: lessons for prevention

BACKGROUND

Few studies have examined the epidemiology of imported malaria in Canadian children. Identifying populations at increased risk in Canada would enable targeted malaria prevention strategies within those groups. The study objective was to describe the epidemiology of malaria diagnosed at British Columbia's Children's Hospital (BCCH) between 1984 and 2001.

METHODS

This was a retrospective chart review of malaria cases identified at BCCH and confirmed through the British Columbia Centre for Disease Control. Demographic and clinical data were recorded on a standardized form.

RESULTS

Malaria was diagnosed 42 times in 40 children (age 24 days to 14.8 years). Thirty cases (71.4%) occurred in 28 Canadian residents, and 12 (28.6%) occurred in immigrant or refugee children. Twenty-six children (65%) were male. Thirty-one children (77.5%) were of East Indian descent. Thirty-three exposures (78.6%) to malaria occurred in the Indian subcontinent. Plasmodium vivax was identified in 37 cases (88.1%), P. falciparum in 3 (7.1%), and the species was unknown in 2 (4.8%). Fourteen cases in the resident children (46.7%) reported pre-travel counselling. Ten resident cases (33.3%) were prescribed chemoprophylaxis, primarily chloroquine, and at least six of them (60%) were non-compliant. The duration of symptoms prior to diagnosis was < 7 days in 27 cases (64.3%), 8 to 30 days in 10 (23.8%), > 30 days in 4 (9.5%) and the duration was unknown in 1 (2.5%). Twenty-four of 36 cases (66.7%) had seen 2 to more than 4 doctors before the diagnosis of malaria was made.

CONCLUSION

The majority of children in our review were of East Indian origin and were exposed to malaria in India. Most had not sought or had received inadequate pre-travel counselling and had been non-compliant with chemoprophylaxis. As malaria is a potentially lethal but preventable disease, strategies to ensure adequate pre-travel counselling for high-risk groups are required.

Side effects of and compliance with malaria prophylaxis in children

BACKGROUND

We wanted to determine the frequency of side effects and compliance with mefloquine and chloroquine used for antimalarial prophylaxis in children 0 to 13 years compared with side effects in same-age children taking prophylactic chloroquine.

METHODS

Subjects and treatment were identified by retrospective medical record review for children < or = 13 years not on other medications who visited a travel clinic between November 1997 and January 2000. Parents were interviewed via telephone in January through March 2000 regarding compliance and side effects.

RESULTS

We reviewed 286 records and contacted 190 of 286 parents (66%). Of these, 177 (93%) parents had first-hand knowledge about the child's compliance with the medication regimen and were interviewed. Subjects were 47% male (median age 6.3 years), contacted a median of 12.4 months (range 2.8 to 28 months) following their clinic visit. Of these, 148 (84%) were prescribed mefloquine, and 29, chloroquine with 77% (136/177) taking the prescribed antimalarial. Most children (30 of 41 [73%]) not receiving their prophylaxis traveled unprotected to endemic area. Sixteen subjects (12% of those taking antimalarials) reported side effects. Eleven of 115 subjects (10%) who took mefloquine, and 5 of 22 subjects (23%) who took chloroquine reported a side effect. Side effects for mefloquine included diarrhea, anorexia, vivid dreams, headache, changes in sleep, hallucinations, and vomiting with 2 subjects stopping mefloquine after seeking medical care. Side effects for chloroquine were headache, nausea, and changes in sleep. No child stopped taking chloroquine. Groups reporting or not reporting a side effect were similar for gender, age, travel destination, antimalarial prescribed, and elapsed time from clinic visit to telephone contact.

CONCLUSIONS

Side effects from antimalarial drug administration occurred in 10 to 23% of patients who took their medication but rarely resulted in stopping prophylaxis. Prescribed antimalarials were sometimes never given. Appropriate counseling on side effects and reasons for faithful administration should accompany antimalarial prophylaxis.

Microtubule-active agents modify nitric oxide production in pulmonary artery endothelial cells

The effects of specific microtubule-active agents on nitric oxide (NO) production were examined in pulmonary artery endothelial cells (PAEC). PAEC were incubated with taxol, which stabilizes microtubules, or nocodazole, which disrupts microtubules, or both for 2-4 h. We then examined NO production, endothelial NO synthase (eNOS) activity, and eNOS association with heat shock protein (HSP) 90. Incubation of PAEC with taxol (15 microM) for 2-4 h resulted in an increase in NO production, eNOS activity, and the amount of HSP90 binding to eNOS. Incubation of PAEC with nocodazole (50 microM) for 2-4 h induced a decrease in NO production, eNOS activity, and the amount of HSP90 binding to eNOS. The presence of taxol in the culture medium prevented the effects of nocodazole on NO production and eNOS activity in PAEC. Geldanamycin, a HSP90 inhibitor, prevented the taxol-induced increase in eNOS activity. Taxol and nocodazole did not affect eNOS, HSP90, and tubulin protein contents in PAEC, as detected using Western blot analysis. These results indicate that the polymerization state of the microtubule cytoskeleton regulates NO production and eNOS activity in PAEC. The changes in eNOS activity induced by modification of microtubules are due, at least in part, to the altered binding of HSP90 to eNOS protein.

Antimalarial chemoprophylaxis in infants and children

The evolving patterns of drug resistance in malaria parasites and changes in recommendations for malaria prevention present a challenge to physicians who advise travellers on chemoprophylaxis. Because compliance with personal protection measures is usually low, children should receive appropriate chemoprophylaxis, including breast-fed infants who are not protected through maternal chemoprophylaxis. For travel to areas where chloroquine resistance has not yet been reported (i.e. parts of Central America, the Caribbean and parts of the Middle East), chloroquine alone is sufficient for antimalarial prophylaxis. Mefloquine is the drug of choice for chemoprophylaxis in areas with chloroquine-resistant Plasmodium falciparum, and can be given to infants and young children. The combination of chloroquine and proguanil is well tolerated in children but is much less effective against drug-resistant malaria. Further research is needed to determine the best dosage regimen for antimalarial drugs used for chemoprophylaxis in children.

Malaria in Brazilian military personnel deployed to Angola

BACKGROUND

Malaria represents one of the most important infectious disease threats to deployed military forces; most personnel from developed countries are nonimmune personnel and are at high risk of infection and clinical malaria. This is especially true for forces deployed to highly-endemic areas in Africa and Southeast Asia where drug-resistant malaria is common.

METHODS

We conducted an outbreak investigation of malaria cases in Angola where a total of 439 nonimmune Brazilian troops were deployed for a 6-month period in 1995-1996. A post-travel medical evaluation was also performed on 338 (77%) of the 439 soldiers upon return to Brazil. Questionnaire, medical record, thick/thin smear, and serum anti-Plasmodium falciparum antibody titer (by IFA) data were obtained. Peak serum mefloquine (M) and methylmefloquine (MM) metabolite levels were measured in a subsample of 66 soldiers (42 cases, 24 nonmalaria controls) who were taking weekly mefloquine prophylaxis (250 mg).

RESULTS

Seventy-eight cases of malaria occurred among the 439 personnel initially interviewed in Angola (attack rate = 18%). Four soldiers were hospitalized, and 3 subsequently died of cerebral malaria. Upon return to Brazil, 63 (19%) of 338 soldiers evaluated were documented to have had clinical symptoms and a diagnosis of malaria while in Angola. In addition, 37 (11%) asymptomatically infected individuals were detected upon return (< 1% parasitemia). Elevated, post-travel anti-P. falciparum IFA titers (> or = 1:64) were seen in 101 (35%) of 292 soldiers tested, and was associated with a prior history of malaria in-country (OR = 3.67, 95% CI 1.98-6.82, p <.001). Noncompliance with weekly mefloquine prophylaxis (250 mg) was associated with a malaria diagnosis in Angola (OR = 3.75, 95% CI 0.97-17.41, p =.03) but not with recent P. falciparum infection (by IFA titer). Mean peak levels (and ratios) of serum M and MM were also found to be lower in those who gave a history of malaria while in Angola.

CONCLUSIONS

Malaria was a significant cause of morbidity among Brazilian Army military personnel deployed to Angola. Mefloquine prophylaxis appeared to protect soldiers from clinical, but not subclinical, P. falciparum infections. Mefloquine noncompliance and an erratic chemoprophylaxis prevention policy contributed to this large outbreak in nonimmune personnel. This report highlights the pressing need for development of newer, more efficacious and practical, prophylactic drug regimens that will reduce the malaria threat to military forces and travelers.

Antisense oligonucleotides targeting malarial aldolase inhibit the asexual erythrocytic stages of Plasmodium falciparum

A major obstacle in the global effort to control malaria is the paucity of anti-malarial drugs. This is compounded by the continuing emergence and spread of resistance to old and new anti-malarial drugs in the malarial parasites. Here we describe the anti-malarial effect of phosphorothioate antisense (AS) oligodeoxynucleotides (ODNs) targeting the aldolase enzyme of Plasmodium falciparum, using the asexual blood stages of the parasite grown in vitro. The blood stages of P. falciparum depend almost entirely on the energy produced by their own glycolysis. Aldolase, the fourth enzyme of the glycolytic pathway, is highly upregulated during the malarial 48-h life cycle. We found that the mRNA of this enzyme can be inhibited, in a sequence specific manner, using AS-ODN to the splice sites on the pre-mRNA of malarial aldolase. At the enzyme level, both specific AS-ODNs for the splice sites, as well as for the translation initiation site on mature mRNA, can inhibit aldolase enzyme activity within the trophozoites of P. falciparum. Furthermore, this downregulation of the malarial aldolase results in a reduction in the production of ATP within the parasite. Finally, the treatment reduces parasitemia. In summary, AS-ODNs targeting the aldolase gene of P. falciparum can interfere with the blood-stage life cycle of this parasite in vitro by inhibiting the expression of the enzyme aldolase which results in decreased malarial glycolysis and energy production. Thus, we conclude that blockade of the expression of malarial glycolytic enzymes using specific AS-ODNs has the potential of a new anti-malarial strategy.

Pediatric imported malaria in New York: delayed diagnosis

The records of 20 children with imported malaria admitted to Kings County Hospital between October 1987 and May 1995 were reviewed. All had a history of recent travel or immigration from a malaria endemic area (West-Africa [16], Central-America [three], and the Caribbean [one]). None of the 10 children with a travel history received appropriate malaria chemoprophylaxis. The most common symptoms and signs were daily fever, chills, and hepatomegaly. Diagnosis was delayed in seven children who were initially felt to have pharyngitis or viral syndrome. Common laboratory findings were anemia and thrombocytopenia. P. falciparum was identified in 70% of the patients. Other species were P. malariae and P. vivax. Complications occurred in six children, hyponatremia in five, seizures in three, and cerebral malaria in one patient. The high incidence of chloroquine-resistant malaria makes chemoprophylaxis difficult in children. The clinical presentation of malaria is nonspecific, and diagnostic delays occur, so a high index of suspicion is needed in children with a travel history.

A week in the life of a travel clinic

International travel has increased enormously in recent years. With the greater movement of people have come increased encounters with a wide variety of diseases: malaria, dengue, cholera, typhoid fever, Ebola virus, and many more. The need for greater scope, consistency, and knowledgeability in pretravel health care to meet these challenges has been met by the emergence of the discipline of travel medicine. Travelers are well advised to become informed of the risks they face and to take steps to minimize those risks. After reviewing a traveler's medical history and a detailed itinerary, a travel medicine practitioner can offer expert advice on behavioral modifications, immunizations, and chemoprophylaxis regimens which will increase the traveler's margin of safety. The issues most frequently addressed in a travel clinic include treatment of traveler's diarrhea, malaria chemoprophylaxis, and immunizations, for hepatitis A, typhoid fever, tetanus/diphtheria, influenza, pneumococcus, hepatitis B, polio, meningococcus, measles, mumps, rubella, varicella, and rabies. Pretravel consultation must consider the age and underlying health problems of the traveler, the nature of the trip (wilderness, jungle, rural, urban, resort, or cruise), the duration of travel, and the latest available information on the site in terms of disease outbreaks, terrorism, and natural calamities.

Malaria

The preeminent infectious threat to unwary tropical travelers, malaria is a preventable, mosquito-borne protozoan infection of red blood cells, which causes fever, anemia, respiratory failure, coma, and death. Malaria is a true medical emergency that requires rapid diagnosis and treatment. Unfortunately, in two thirds of tropical travelers who die of malaria, either treatment is delayed or the diagnosis is simply missed. Every tropical traveler with fever or unexplained, flu-like illness must be assumed to have life-threatening malaria and must have thick and thin blood smears immediately examined to confirm the diagnosis.

Protecting travelers against infections: immunizations and other preventive strategies

Every year thousands of Americans travel abroad and risk encountering diseases to which they are not normally exposed. With pretravel counseling from their physician, travelers can substantially reduce or eliminate the risk of many common travel-related infectious diseases. Patients should be informed about required and recommended vaccinations, chemoprophylaxis and other preventive measures, and strategies for self-treatment, should an infection arise during travel. Up-to-date travel health resources, including sites on the World Wide Web, can assist physicians in advising patients about immunizations and other preventive measures recommended for travel to endemic areas.

Falciparum malaria

Falciparum malaria is one of the most common infectious illnesses in the world and can progress rapidly to coma and death in the nonimmune patient. The presentation is nonspecific, so blood smears must be made and read quickly. Proper therapy requires taking into account drug resistance, recognizing the signs of severe malaria, and proper treatment for complications. Long-sleeved clothing, bed nets, insecticides, and chemoprophylaxis can help prevent malaria, but the infection must be suspected in any traveler returning from an endemic area. This article reviews epidemiology, diagnosis, treatment, and prevention of falciparum malaria in the temperate zone.

Malaria among United States troops in Somalia

PURPOSE

United States military personnel deployed to Somalia were at risk for malaria, including chloroquine-resistant Plasmodium falciparum malaria. This report details laboratory, clinical, preventive, and therapeutic aspects of malaria in this cohort.

PATIENTS AND METHODS

The study took place in US military field hospitals in Somalia, with US troops deployed to Somalia between December 1992 and May 1993. Centralized clinical care and country-wide disease surveillance facilitated standardized laboratory diagnosis, clinical records, epidemiologic studies, and assessment of chemoprophylactic efficacy.

RESULTS

Forty-eight cases of malaria occurred among US troops while in Somalia; 41 of these cases were P falciparum. Risk factors associated with malaria included: noncompliance with recommended chemoprophylaxis (odds ratio [OR] 2.4); failure to use bed nets (OR 2.6); and failure to keep sleeves rolled down (OR 2.2). Some patients developed malaria in spite of mefloquine (n = 8) or doxycycline (n = 5) levels of compatible with chemoprophylactic compliance. Five mefloquine failures had both serum levels > or = 650 ng/mL and metabolite:mefloquine ratios over 2, indicating chemoprophylactic failure. All cases were successfully treated, including 1 patient who developed cerebral malaria.

CONCLUSIONS

P falciparum malaria attack rates were substantial in the first several weeks of Operation Restore Hope. While most cases occurred because of noncompliance with personal protective measures or chemoprophylaxis, both mefloquine and doxycycline chemoprophylactic failures occurred. Military or civilian travelers to East Africa must be scrupulous in their attention to both chemoprophylaxis and personal protection measures.

Illness in Journalists and Relief Workers Involved in International Humanitarian Assistance Efforts in Somalia, 1992-93

Background: Journalists and relief workers participating in international relief efforts in Somalia following the intervention of outside armed forces in late 1992, were faced with a number of threats to their health. Principally these threats were from endemic infectious diseases and trauma. Methods: In-patient, emergency clinic, and laboratory records of U.S. military field hospitals, which provided the only available sophisticated medical care in Somalia during most of the study period (December 15, 1992, to February 15, 1993), were reviewed to determine the number of workers evaluated and the causes of their illnesses. In addition, two questionnaire surveys were conducted to elucidate risk factors for illness in these groups. Results: One hundred and thirty-eight journalists and relief workers, primarily from Europe and North America, were evaluated at a hospital for a variety of common travel-associated health problems, including diarrhea (33%), acute respiratory infection (21%), other febrile illnesses (11%), hepatitis (2%), major trauma (6%), and minor trauma (13%). Documented infectious disease pathogens included Plasmodium falciparum (7 cases), Shigella sp (3 cases), enterotoxigenic Escherichia coli (ETEC) (3 cases), dengue virus-2 (2 cases), and hepatitis E virus (3 cases). Two relief workers were killed by gunshot wounds. In the questionnaire surveys of 104 journalists and 98 relief workers, 84% of respondents reported that they had received some pretravel medical advice, but only 70% sought a medical consultation in person. Thirty-four percent were not receiving a recommended antimalarial chemoprophylaxis regimen, and only 10% obtained a fluoroquinolone antimicrobial drug for self treatment of diarrhea. Sixty-four percent of both groups combined, reported having had diarrhea, and 26% experienced a nondiarrheal febrile illness. Sixty-eight percent reported that their work performance was adversely affected by illness. In multivariate logistic regression analyses, factors associated with an increased risk of diarrhea were age < 35 years (OR 1.5, 95% CI 1.1-1.9); residence in Somalia for more than 21 days (OR 1.7, 95% CI 1.3-2.1); and regular consumption of local food and water (OR 3.8, 95% CI 3.4-4.2). Factors associated with nondiarrheal febrile illness were age < 35 years (OR 1.4, 95% CI 1.1-1.8); residence in Somalia for more than 21 days (OR 1.8, 95% CI 1.4-2.2); and not having had an in-person pretravel medical consultation (OR 2.0, 95% CI 1.5-3.0). Conclusions: These data indicate that journalists and relief workers who traveled to Somalia in response to the massive humanitarian crisis themselves experienced substantial health problems. Improved pretravel medical preparation might prevent or limit illness in these unique groups and improve the efficiency of future disaster response efforts. (J Travel Med 2:70-76, 1995)

Arguments against Chemoprophylaxis in Areas at Low Risk for Chloroquine-Resistant Plasmodium falciparum

Chemoprophylaxis of malaria prevents the disease not the infection (suppressive chemoprophylaxis) with "high levels of confusion and low levels of compliance." The magnitude of danger of contracting malaria for travelers varies in several endemic zones. In West Africa, without prophylaxis, malaria is estimated to have an incidence of 1.4% per person per month. In South and Central America, the incidence is 0.05 and 0.01% per month, respectively. In Asia, the transmission and percentage of infection due to Plasmodium falciparum is much lower. The dangers of chemoprophylaxis in an area at low risk for chloroquine resistant P. falciparum are a reality. Incompletely active drugs change clinical manifestations, and changes in clinical manifestations delay the establishment of a correct diagnosis. The rate of adverse events is 15-20%, and hospitalization due to side effects of prophylaxis occurs in one in 10,000 travelers. Neuropsychiatric side effects have been reported with both mefloquine and chloroquine. A false sense of security can hinder a physician practicing in a nonendemic area from thinking of malaria when a traveler returns with fever. To complicate the picture, in many countries, there is an emerging drug resistance in P. falciparum as well as an emerging chloroquine resistance in P. vivax strains (20% in New Guinea and Irian Jaya). In short, no available chemoprophylaxis is free from toxicity, and its efficacy is never 100%. Alternatives to conventional chemoprophylaxis are encouraged in areas of low morbidity of malaria. In areas where P. vivax occurs primarily, and when the risk of serious side effects from chemoprophylaxis outweighs the risk of life threatening P. falciparum infection, there are four alternative strategies.2,3 The first strategy is that the traveler avoid mosquito bites. With a compulsive attitude, a high degree of protection can be realized with the proper use of pyrethrum-impregnated mosquito netting, topical DEET-containing insect repellents and impregnated protective clothing. Secondly, when the stay in malaria-endemic areas is less than 1 week, the disease will appear after returning home. No chemoprophylaxis is needed during the journey. With the onset of fever, diagnosis and therapy are performed without delay at home. This strategy assumes the participation of an informed physician. A third strategy is standby treatment, which is defined by the World Health Organization (WHO) as the use of antimalarial drugs carried for self administration when fever occurs and prompt medical attention is not available. Standby treatment is a safe option for an informed tourist traveling to areas at low risk of malaria or in areas where chemoprophylaxis may not be effective. Likewise, self therapy might be preferred for travelers who make frequent journeys characterized by brief and successive visits to malarious and nonmalarious areas, and for long-term travelers, and expatriots. Standby treatment minimizes drug overuse, demands early investigation of any febrile illness, and insists that effective treatment is given rapidly for P. falciparum malaria that occurs in nonimmune persons. This strategy is the responsibility assumed by teaching physicians and appears to be more advantageous than classic long-term chemoprophylaxis. A fourth strategy is systematic curative treatment carried out under supervision upon a traveler's return home. The administration of halofantrine after departure from endemic areas was studied for the prevention of P. falciparum malaria after short-term exposure,4 but the adverse cardiac effects of this drug obviates the usefulness of this "radical cure". Possibly the administration of doxycycline or azithromycin after departure from malarious areas could prevent P. falciparum malaria after short-term exposure and with less deleterious side effects. This approach requires more research, and again this will be the responsibility of physicians.