Category Archives: Epidemiology

World TB Day: considering malaria coinfection

Typical of our big disease mindset, most donor agencies think of HIV-Tuberculosis coinfection when addressing a connection among the three Global Fund diseases. Take as an example a recent News Flash from the Global Fund: “In a major step toward addressing the growing number of people affected by co-infection with tuberculosis and HIV, the Global Fund is improving the way it approaches treatment programs in countries with high rates of each disease. Millions of people infected with both TB and HIV could benefit from better services.”

World TB DayThe possible neglect of TB and malaria interactions might be understood by the fact that HIV and TB have much wider areas of endemicity than malaria. On the other hand both HIV and TB are disproportionately represented in malaria endemic Africa. At present the main connection between malaria and TB is the fact that they must share out of the same ‘envelope’ when new Global Fund support is distributed through the new funding mechanism to countries, a process that some see as moving more toward donor control and AID effectiveness and away from human rights.

Today the Stop-TB Partnership and related organizations are observing World TB day by noting that at least one-third of newly infected people will not get appropriate treatment. Poor access to or inadequate and inappropriate treatment plagues all three diseases, especially where health systems are weak.  We need an integrated approach to strengthen systems and improve care.

In the meantime, researchers have maintained interest in possible interactions between TB and malaria. For example Ann-Kristin Mueller and colleagues have published a study entitled, “An Experimental Model to Study Tuberculosis-Malaria Coinfection upon Natural Transmission of Mycobacterium tuberculosis and Plasmodium berghei,” using a mouse model. A slide presentation on their work is also seen at the website. As Mueller notes, “Concurrent infections most likely modulate the respective immune response to each single pathogen and may thereby affect pathogenesis and disease outcome. Coinfected patients may also respond differentially to anti-infective interventions.”

Mueller puts is mildly when she says that TB-malaria coinfection “has not been studied in detail.” We might need to step back in time over 2900 years where according to Lalremruata and colleagues, “the notion that the agricultural boom and dense crowding occurred in this region (southwest of modern Cairo), especially under the Ptolemies, highly increased the probability for the manifestation and spread of tuberculosis. Here we extend back-wards to ca. 800 BC new evidence for malaria tropica and human tuberculosis co-occurrence in ancient Lower Egypt.”

In a 2013 review on “Co-infection of tuberculosis and parasitic diseases in humans,” Xin-Xu Li and Xiao-Nong Zhou found only two direct reports of malaria and TB co-infection, one a case report from 1945 and the other on host response in malaria and depression of defense against tuberculosis from 1999.

Finally a review of hospital records from 2007 in Luanda, Angola found that Malaria was diagnosed during admission and hospital stay in 37.5% of TB patients. Clearly the time has come to take coinfection seriously as both a research and service delivery topic.

Man’s Best Friend May Harbor Guinea Worm

Border Collie 3smChad had been free of debilitating guinea worm disease for a decade when ten new cases were uncovered in 2010. Logistical factors have prevented containment and the disease persists into the current transmission season. The Ministry of Health in Chad is currently examining 9 cases of human guinea worm but also 50 cases in dogs and one in a cat.

Donald Hopkins and colleagues recently explained that “Guinea worms in dogs have been reported for almost a century in some areas of Asia, Africa, and North America, including in some recently endemic countries that have interrupted transmission, but disease caused by D. medinensis has never been reported again after human transmission was interrupted.” In this situation where the cases in dogs far outnumber those in humans, one wonders hat the future holds for breaking transmission.

foot- close up2 smTwo key lessons from this experience are to be learned by the malaria community. First is the fact that once eliminated, an infectious disease can return.  The context though probably relates to the neighborhood. Post-conflict South Sudan is one of the few remaining countries with continued guinea worm transmission and refugee movement may have contributed to the problem.

The second lesson is the potential for inter-species transmission. Plasmodium knowlesi, a disease of primates, appears about to become entrenched in the human population of Southeast Asia. Cases of monkeys having P. vivax have been documented in South America and Africa.  Elimination of human transmission of malaria may be hampered by non-human reservoirs.

We may not be able to say that elimination has occurred until there is no local transmission of any species of Plasmodium that affect humans in any other life form.  We have a hard enough time tracking malaria in humans when it falls below levels detectable by microscopes and rapid tests. What of the challenges of tracking it in monkeys?  Maybe these complications explain why to date smallpox remains the exception to the eradication rule.

Are non-communicable diseases actually communicable?

Much of the discussion around global health and post-Millennium Development Goals focuses on non-communicable diseases (NCDs) including cardiovascular problems, diabetes, cancers and the the like.  While it is important to recognize that low income nations are not plagued with both communicable and non-communicable diseases, we do not want the greater focus on NCDs in richer countries to overshadow the problems of malaria, pneumonia, TB, diarrhea and other child killers in poorer countries.

dscn7742-chw-flipchart.jpgA major reason for us not to lose focus on communicable diseases was recently reported from the Wellcome Trust on research they have supported in Malawi. The researchers found that the malaria parasite, Plasmodium falciparum, is able to “cause inflammation in blood vessel walls, making them more sticky so that the infected red blood cells can cling to the sides. Being able to stick to the blood vessels in vital organs allows the parasite to hide away from the immune system, a process called sequestration. When it occurs in the brain it causes a more severe form of the disease called cerebral malaria, associated with seizures, coma and sometimes death.”

The researchers also surmised that if this complication does not kill people in childhood, the damage to blood vessel walls can have more long lasting effects. In particular they noted that, “Chronic changes to the blood vessels like these could an important contributing factor to cardiovascular disease later in life.”

The link between malaria and Endemic Burkitt lymphoma (eBL) continues to be explored. Recently adding to this long history of eBL research, Peter Aka and colleagues reported that. “Anti–HRP-II (Plasmodium falciparum histidine-rich protein-II) antibodies suggest that recent malaria infection triggers the onset of eBL.”

In a review of intrauterine growth retardation (IUGR) Demicheva and Crispi observed that, “Several clinical and experimental studies showed that IUGR fetuses present signs of cardiac dysfunction in utero that persist postnatally and may condition higher cardiovascular risk later in life.” In endemic regions, malaria in pregnancy is a major cause of IUGR and thus low birth weight.

Preventing malaria therefore saves lives now and in the future. Ignoring malaria now adds greater burdens to the health system and national productivity tomorrow. We need to maintain our investments in malaria both globally and in and by endemic countries themselves.

Low levels of placental parasitemia among women delivering in health facilities in Zanzibar: policy implications for IPTp

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Presented at Jhpiego’s Mini-University on 24 June 2013 in Baltimore by Marya Plotkin, Elaine Roman, and Maryjane Lacoste

Malaria in pregnancy (MIP) is a threat to the pregnant women, the unborn child and the newborn and infant. Intermittent Preventive Treatment during pregnancy (IPTp) is one of the few interventions available that specifically targets and protects pregnant women.  As malaria prevalence drops when countries aim at malaria elimination, we need to examine the continued role of IPTp and search for alternatives.

zanzibar-placental-malaria-study-sm.jpgFrom August 2011 to September 2012, Jhpiego partnered with the Zanzibar Ministry of Health to conduct a study looking at the prevalence of placental malaria infection among women delivering in selected health facilities in Zanzibar who had not had IPTp during the course of their pregnancy. The community-level malaria positivity rate in Zanzibar declined from as high as 20% in 2005 to 1.6% in 2011. In Zanzibar as in the rest of Tanzania, IPTp coverage has been quite low, but pregnant women have access to long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) is practised in the islands.

Midwives in six clinics in in Unguja and Pemba tested the women using PCR at delivery. Of the 1,356 women with no IPTp exposure enrolled in the study, only nine (0.6%) were found to have placental malaria (95% CI 0.2–1%). Thus, even without benefit of IPTp, other interventions appear to be protecting pregnant women to some degree.

zanzibar-pcr-sm.jpgEstimations of the costs of IPTp program put the annual expenditure at $114,678, while the annual cost of intermittent screening and treatment with RDTs (ISTp) would be $155,294.  Given the extraordinarily low prevalence of malaria in pregnancy, as well as pilot experience of testing in the ANC setting, there is a strong argument for adopting ISTp and dropping IPTp in Zanzibar.

To do so, the authors argue, thresholds of prevalence or incidence of malaria infection must be set in advance in order to trigger a reconsideration of the IPTp decision, and surveillance of malaria infection in pregnancy must be strengthened.

WHO has recently issued new guidance recommending continuation of IPTp where it is currently being practiced, making Zanzibar’s decision to maintain or discontinue IPTp of particular interest to the malaria in pregnancy community. Better guidance is needed on MIP services as countries move closer to malaria elimination.

Household Survey Used to Study Human Population Movement on Malaria Transmission in Southern Zambia

Karen E. Kirk, a MSPH-Internal Health Candidate at the Johns Hopkins Bloomberg School of Public Health has written this guest posting based on a poster she presented at the School’s Global Health Day earlier this month.

The inability to eliminate malaria in low endemic settings due to importation by infected individuals is considered a potential barrier in the fight to eradicate malaria worldwide.  Individuals living in the rural Choma District, Southern Province, Zambia have seen a dramatic decline in malaria since 2007 with the implementation of malaria control programs that include active case detection; mass distribution of insecticidal treated nets (ITNs); and widespread use of indoor residual spraying (IRS).  However, malaria elimination has still not been achieved in this region of the country.

blog-kirk-field-staff-collecting-blood-samples-2.jpgThe first photo shows field staff collecting blood samples from household members to test for malaria parasitemia in Choma District

A household survey was conducted in the Choma District to assess human population movement (HPM) and its association with confirmed or suspected malaria cases of individuals living in the district. The survey looked at travel history of 196 individuals from 42 randomly selected households between December 2012 and March 2013.  It collected data on travel patterns of individuals from the previous 4 weeks who stayed overnight for at least one night outside of their village. In addition, it collected blood sample for the testing of malaria parasitemia.  This survey was included in both the longitudinal and cross-sectional household surveys being conducted by the International Centers of Excellence in Malaria Research (ICEMR).

blog-kirk-community-survey-2.jpgThe second photo shows Field staff conducting malaria community health and HPM survey with mother in Choma District

Of the 196 individuals surveyed there were 97 (49.5%) adults (ages >17), and 99 (51.5%) children (<17).  There were a total of 34 trips taken by 31 (15.8%) individuals, 18 adults and 13 children. The majority of these individuals (59.3%) traveled for 7 days or less and 27 (87.1%) individuals traveled within the Choma District.  No malaria cases were detected in this study and therefore the results of this preliminary data were not able to show an association between HPM and malaria incidence rates.  However, with an increase in data collected over time, trends could be ascertained to determine seasonal patterns with HPM and its impact on malaria incidence rates in this hypoendemic setting.  The hope is that with adequate funding in malaria research with HPM, these types of studies can contribute important information on malaria transmission and help achieve the goal of regional elimination and ultimately eradication of this harmful disease.

[Bill Moss of JHSPH served as Principal Investor of this project]

Malaria Related Presentations at APHA Conference 2012 San Francisco

aphabanner-75.gifThe APHA schedule search turned up 31 presentations, panels and posters related to malaria. If you are attending the American Public Health Assocation 140th annual meeting, take advantage of these.

1.    Barriers to practicing healthy behaviors for malaria prevention and child nutrition in Zambia: A qualitative study 263984 Barriers to practicing healthy behaviors for malaria prevention and child nutrition in Zambia: A qualitative study Wednesday, October 31, 2012 Lovemore Mwanza , Research, Monitoring, and Evaluation …

2.    Prevalence of Malaria in Pregnancy as Rwanda Moves towards Malaria Elimination
265783 Prevalence of Malaria in Pregnancy as Rwanda Moves towards Malaria Elimination Tuesday, October 30, 2012 : 3:00 PM – 3:15 PM Corine Karema …

3.    Malaria diagnosis: Perspectives from caregivers and health staff, Makarfi, Nigeria 261566 Malaria diagnosis: Perspectives from caregivers and health staff, Makarfi, Nigeria Tuesday, October 30, 2012 : 8:35 AM – 8:50 AM Olufemi …

4.    Impact of climate and land use influencing the spatial and temporal distribution of malaria risk in the Amazon 261531 Impact of climate and land use influencing the spatial and temporal distribution of malaria risk in the Amazon Tuesday, October 30, 2012 Beth J. Feingold, PhD, MESc, MPH , Department of Earth and Planetary …

4c_sm_apha_20128.gif5.    Measuring Malaria Advocacy Outcomes 270759 Measuring MalariaAdvocacy Outcomes Monday, October 29, 2012 : 11:30 AM – 11:45 AM Marc Boulay, PhD , Center for Communication Programs, …

6.    How can we Accelerate Programming for Malaria in Pregnancy? 274603 How can we Accelerate Programming for Malaria in Pregnancy? Monday, October 29, 2012 : 11:30 AM – 11:50 AM William R. Brieger, MPH, CHES, DrPH , Jhpiego, …

7.    Improper maternity wear, mean providers, and vomiting: Barriers to timely IPTp uptake for malaria prevention during pregnancy in rural Zambia 266032 Improper maternity wear, mean providers, and vomiting: Barriers to timely IPTp uptake for malaria prevention during pregnancy in rural Zambia Tuesday, October 30, 2012 : 3:15 PM – 3:30 PM Hilary Schwandt, PhD, MHS …

8.    How local government health workers in Nigeria manage suspected malaria cases 265691 How local government health workers in Nigeria manage suspected malaria cases Tuesday, October 30, 2012 : 2:45 PM – 3:00 PM Bright Orji, MPH , Nigeria, Jhpiego, Baltimore, MD William …

9.    Challenges of implementing intermittent preventive treatment in Zambia for malaria prevention in pregnancy 263075 Challenges of implementing intermittent preventive treatment in Zambia for malaria prevention in pregnancy Tuesday, October 30, 2012 : 2:30 PM – 2:45 PM Peter Mumba, MD, MSc , Zambia Integrated …

10.    Contemporary Issues in Malaria in Pregnancy: Why worry now? 274600 Contemporary Issues in Malaria in Pregnancy: Why worry now? Monday, October 29, 2012 : 10:30 AM – 10:50 AM Mary Nell Wegner, EdM, MPH …

11.    Community-based Interventions for Malaria in Pregnancy: Findings from Mozambique 274602 Community-based Interventions forMalaria in Pregnancy: Findings from Mozambique Monday, October 29, 2012 : 11:10 AM – 11:30 AM Leonardo Chavane, MD, MPH , …

12.    Spatial access to malaria treatment in Kenya and its impact on health seeking behavior: A GIS based study 270764 Spatial access to malaria treatment in Kenya and its impact on health seeking behavior: A GIS based study Monday, October 29, 2012 Brittany Goettsch, …

13.    Challenges of Addressing Malaria in Pregnancy through Antenatal Care Services: A Nigerian perspective 274601 Challenges of Addressing Malaria in Pregnancy through Antenatal Care Services: A Nigerian perspective Monday, October 29, 2012 : 10:50 AM – 11:10 AM Oladosu …

14.    Invited Panel: Malaria in Pregnancy: An urgent yet solvable problem uniting the maternal health and malaria communities in Africa 3150.0 Invited Panel: Malaria in Pregnancy: An urgent yet solvable problem uniting the maternal health andmalaria communities in Africa Monday, October 29, 2012: …

15.    Malaria & Vector-Borne Diseases 4320.0 Malaria & Vector-Borne Diseases Tuesday, October 30, 2012: 2:30 PM – 4:00 PM Oral Moderator: Pablo Aguilar, MD MHSc 2:30pm Challenges of implementing …

16.    Poster Session: Nutrition … 2012: 8:30 AM – 9:30 AM Poster Organizer: Mike S. Bailey, MA / Co-Chair Board 1 Barriers to practicing healthy behaviors for malaria prevention and child nutrition in Zambia: A qualitative study Lovemore Mwanza, Rikki Welch, MA, John Manda, Samantha Herrera, Ana Claudia …

17.    *Poster Session*: Emerging issues in environmental public health … MCP and Devon Payne-Sturges, DrPH Board 4 Impact of climate and land use influencing the spatial and temporal distribution of malaria risk in the Amazon Beth J. Feingold, PhD, MESc, MPH, Benjamin Zaitchik, PhD, Victoria Shelus, BSc and William Kuang-Yao Pan, …

18.    Innovation in Technology: Public Health Models Posters 2 … practices serving underserved communities Kristina Vasileva, MPH, Mandy Smith Ryan, PhD and Mariceli Comellas, MA Board 10 Spatial access to malaria treatment in Kenya and its impact on health seeking behavior: A GIS based study Brittany Goettsch, MPH Candiate See individual …

19.    Infectious Disease Epidemiology 2 … AM – 10:00 AM Oral This session will provide new findings in the area of infectious disease epidemiology including the areas of malaria, TB, and influenza. Session Objectives: Assess the adequacy of zip code tabulation areas as a proxy for census tracts when …

20.    Advocacy & Global Health … Kovach, MPH, A. Elisabeth Sommerfelt, MD, MS, Alice Nkoroi, MS, Robert Mwadime, PhD and Ferdousi Begum, MBBS, MS 11:30am Measuring Malaria Advocacy Outcomes Marc Boulay, PhD, Claudia Vondrasek, MPH, Matt Lynch, PhD and Sarah Dalglish, MPH See individual abstracts for presenting …

21.    Seeing the obscured: A social epidemiological assessment of malaria’s reemergence in deforested regions 269174 Seeing the obscured: A social epidemiological assessment of malaria’s reemergence in deforested regions Tuesday, October 30, 2012 Beth Phillips, MPH , Mel and Enid Zuckerman College of Public Health, …

22.    Factors associated with completion of Intermittent Preventative Therapy (IPT) among pregnant women in Malawi … Sciences for Health, Arlington, VA Allison Zakaliya , Baylor Children’s Foundation, Baylor Children’s Foundation, Lilongwe, Malawi Misheck Luhanga , National Malaria Control Program, Ministry of Health, Lilongwe, Malawi Johnes Moyenda , Mpemba Health center, Ministry of Health, Blantyre, Malawi Doreen Ali…

23.    Designing a translational epidemiologic study: Chloroquine and breast cancer chemoprevention in Returned Peace Corps Volunteers … present the design of a novel translational epidemiologic approach to confirm preclinical data on the chemopreventive potential of a well-characterized anti-malarial drug. BACKGROUND: Exposure to chloroquine, an off-patent anti-malarial drug with a 60-year history of use by millions, reduces the incidence…

24.    Exploratory assessment of alternative use of bed nets within the Arisi zone in Ethiopia: Findings from household interviews and observations … Thaddeus Pennas, MS , C-Change, FHI360, Washington, DC Background: Distribution of long lasting insecticide-treated nets (LLINs) is one of four malariaprevention interventions being scaled up in sub-Saharan Africa. Correct and consistent use of LLINs by households is central to the …

25.    Young and vulnerable: Comparing delivery care, domestic violence, and child undernutrition between adolescent girls and women in Bangladesh … and Asia on topics related to evidence-based advocacy to improve nutrition, reduce maternal mortality, increase newborn survival, and decrease the malariaburden; written on child health and nutrition; and domestic violence against women. Carried out the data assessment and analyses. Have …

26.    Determinants of insecticide treated bednet (ITN) use by households in Nigeria … tying ITN to nails on the wall, and frequent washing of the ITN. The number of times a child had malaria in past 6 months, where child slept at night, and use of other malaria control measures were also associated with …

27.    Measuring the competencies and skills of midwives in an accelerated training program in Zambia … 25% felt they were not competent to treat patients with pneumonia while only 2% felt incompetent to manage patients with malaria; neither were statistically associated with duration of service (X2=61539;2=3.163, p=0.075; X2=61539;2=0.002, p=0.962 respectively). Conclusions: The assessment showed that the certified …

28.    Community Health Workers and Prevention: How to measure effectiveness of preventive community health programs centered on CHW … effectiveness of their preventive messages and adapt them for maximum results. With an effective tool to measure the effectiveness of malaria and HIV prevention and messages on hand washing and adequate nutrition, CHW receive immediate feedback on the challenges their communities …

29.    Improving access to preventive healthcare in Haiti: A community based approach … under five years of age, prevention messages delivered through skits, micronutrient supplementation, mosquito nets to pregnant women to help preventMalaria in Pregnancy, and blood pressure checks for all. Preliminary data have shown increased uptake of services and better maternal and …

30.    Mobile technology-based approach for facilitating health data collection, sharing, analysis and use in Uganda … of health centers through UHIN including monthly HMIS reports, disease surveillance data, and specific reports related to HIV/AIDS, TB, and malaria. Rural hospitals use UHIN for capturing data on electronic daily registers such as PMTCT, in-patient, lab, HIV counseling, and ART …

31.    Climate change and blood safety … transmission of dengue fever occurred in France in 2010. Other infectious agents are of concern such as Hanta virus, leishmaniasis, malaria, tick-borne encephalitis and their relationship to climate change and blood safety will be discussed. These insights call for changes in …

Mapping Malaria – targeting interventions

The World Bank has announced a project in Nigeria to map the location of high risk populations in order to target interventions more effectively. According to the Bank, “In Nigeria, populations at greatest risk for HIV comprise 3.4% of population but account for up to 40% of new infections.” We hope that such efforts will help decrease disease and not increase stigma and discrimination. But clearly, mapping is an important tool to understand a health problem.

map-pf_mean_2010_bfa-sm.pngMapping on the broadest sense has been undertaken for malaria.  An earlier incarnation of African mapping was MARA, which was founded on the idea that mapping could help target resources.  More recently the Malaria Atlas Project (MAP) has tried to refine the mapping process drawing on a wide variety of epidemiological studies in endemic countries. MAP has moved beyond Africa and looks at both P. falciparum  and  P. vivax.

Detailed country maps from MARA and MAP on a country by country basis help us see different transmission and seasonal patterns of disease.  From this we can target regions in a country that may benefit more from indoor residual spraying or intermittent preventive treatment.

The interesting thing about malaria is that transmission can vary even on a micro level.  Urban malaria is a case in point, where there are fewer anopheles mosquito breeding sites in densely populated urban slums, and more in areas where people have gardens.

Even in rural areas transmission can vary by proximity to the watery breeding sources of mosquitoes. Factors ranging from deforestation to rice farming play a localized role in transmission mapping. This should lead to spatial targeting of interventions.

We need to carry mapping and thereby appropriate interventions to the community level to have the greatest effect. At present we are of lucky to get any supplies of malaria commodities into a country and distributed to the next administrative level.  Micro mapping and planning may sound like a dream in this context, but if we are to succeed in eliminating the disease, we may need to carry the fight from one neighborhood, hamlet or block to the next.  Such surveillance is the key to a malaria free future.

Malaria and Older Adults

Recent research has stressed the increase risk of death from malaria that elderly tourists face. Mortality from P. falciparum malaria increased steadily with increasing age with case fatality rate peaking in the group aged over 65 years. The authors explain that, “These data are supported by previous reports of increased case fatality and higher levels of parasitaemia in elderly people,” but the three studies cited focus only on travelers and tourists back in the UK, not adults and elderly people living in endemic regions.

This leads on to wonder about the risks malaria poses to elderly people in endemic countries, especially as populations throughout the world are aging.

While the recent controversial study that suggests that malaria deaths in adults have been underestimated world-wide, it does not specifically address the suspected prevalence of malaria morbidity and mortality in older adults. Specifically the authors “estimated more deaths in individuals aged 5 years or older than has been estimated in previous studies: 435 000 (307 000-658 000) deaths in Africa and 89 000 (33 000-177 000) deaths outside of Africa in 2010.”

Concerning the “outside Africa” component mentioned above, a study of adult and child malaria mortality (both falciparum and vivax) in India published in 2010 did report a higher malaria mortality risk in persons over 60 years of age.

More documentation on malaria morbidity and mortality in persons over 60 years in age in endemic countries is needed. Although portions of this segment of the population may no longer be in their productive years, they do consume health care resources, and as grandparents play important roles in child care.

scan_io-012-sm.jpgIn addition there is need to ascertain reasons for any differing patterns that may be detected. The study on tourists did not think that co-morbidity in elderly patients was responsible but instead implied that older people on holidays may forget to take their prophylaxis.

What differences in health behavior might be found in elderly populations in malaria endemic countries – maybe greater reliance on less efficacious indigenous concoctions? Are there differences in terms of perceptions of severity and seriousness of illness? Are there differences in care access?

The respect and quality of care we give the elderly says a lot about the societies in which we live.

Malaria Transmission: are we out of the woods?

Human activity is leading to deforestation in central Africa and bringing hunters and people in closer contact with our primate cousins and their collection of pathogens.  The Global Viral Forecasting Initiative is carefully studying these contacts between humans and other vertebrates in an effort to identify possible new viral epidemics. In the process they have also made observations about the origins of human malaria and the potential for transmission of primate plasmodium infections to people.

While transmission of malaria species between humans and other primates has been documented in South America and Africa, Southeast Asia has received the most attention.  In fact, the question is being raised as to whether P. knowlesi is becoming the fifth human malaria parasite. If new infections as well as new species are arising from the primate world, this has grave implications for efforts to eliminate malaria worldwide.

A recent study from Vietnam found that, “showed P. knowlesi infections in 32 (26%) persons with malaria (n = 125) and in 31 (43%) sporozoite-positive An. dirus mosquitoes (n = 73). The authors observed and warned that …

P. knowlesi–co-infected patients were largely asymptomatic and were concentrated among ethnic minority families who commonly spend nights in the forest. P. knowlesi carriers were significantly younger than those infected with other malaria parasite species. These results imply that even if human malaria could be eliminated, forests that harbor An. dirus mosquitoes and macaque monkeys will remain a reservoir for the zoonotic transmission of P. knowlesi.

In another study researchers confirmed P. knowlesi in humans in Cambodia. This is worrisome especially since Cambodia is one of the locations where resistance to artemisinin-based medicines is rising.

gametocytes-of-p-knowlesi-in-a-giemsa-stained-thin-blood-smear-from-a-patient-that-traveled-to-the-philippines.jpgLikewise, researchers in Malaysia reported that, “P. knowlesi is a major cause of severe and fatal malaria in Sabah. Artemisinin derivatives rapidly clear parasitemia and are efficacious in treating uncomplicated and severe knowlesi malaria.”  Gametocytes of P. knowlesi in a Giemsa-stained thin blood smear from a patient that traveled to the Philippines can be seen in the attached photo from CDC.

Simian reservoirs of malaria throughout Southeast Asia pose a major challenge for control efforts.  Tackling this problem in the forest habitats where people come into contact with monkeys will be daunting – we are not out of the woods yet for malaria elimination.

Malaria in the Military

November 11th is Veteran’s Day in the United States. Over the years soldiers have been vulnerable to malaria. During the U.S. Civil War 150 years ago over 14,000 Union troops are estimated to have died from malaria. While death estimates were not available for the Confederates, it was thought that over 40,000 malaria cases occurred in an 18-month period in the middle of the war.

nyt-mali-7a.jpgToday places like Afghanistan and the Horn of Africa pose a malaria threat to troops, so there is malaria prophylaxis for soldiers. Sometimes the prevention itself poses problems. “The Army has dropped Lariam — the drug linked to side effects including suicidal tendencies, anxiety, aggression and paranoia,” and now prefers doxycycline for people who may react to mefloquine.

The military takes malaria seriously now. The Walter Reed Army Institute of Research (WRAIR) puts a priority on malaria research since, “Malaria remains highly relevant to the military because of its prevalence, variety (there are four species that infect humans), debilitating nature, potential lethality, and tendency to become resistant to drugs. No organization in the world has WRAIR’s experience in the complete spectrum of malaria research.”

WRAIR’s “Work on a vaccine is also progressing. Advanced molecular, genetic, and biomedical technologies are now being employed to produce candidate malaria vaccines. Field trials of these candidate pharmaceuticals are an essential part of the program and are underway in Thailand and Kenya.”

The military of all nations are at risk when they serve in malaria endemic areas. For example, a Philippine soldier “succumbed to malaria on 23 October 2008 while serving as a military observer with the U.N. Mission in Sudan.”

Another concern of malaria in the military is the potential for soldiers who contract malaria for spreading it to other countries or bringing it home. It was reported that Soviet soldiers serving in Afghanistan some years ago brought the disease back to republics in the Caucasus and Central Asia. Though this particular spread could be controlled, not all situations may be so fortunate.

Today a variety of injury and mental health problems may overwhelm the effects of malaria on soldiers. Still, soldiers are at risk. For example in 2002, “38 cases of malaria were identifiedin a 725-man Ranger Task Force that deployed to eastern Afghanistan.” Also over a 6-year span the Defense Medical Surveillance System reported 423 cases of malaria including Plasmodium vivax, P. falciparum, P. ovale, and P. malaria. A big challenge is the inability of health systems in non-endemic countries to treat and save lives of soldiers who return home with the disease.

There are basically two lessons from this issue. First malaria control must recognize that soldiers who may not be immune when they enter a malaria endemic war zone are at risk of malaria death. Secondly, as a mobile population soldiers have the potential for reintroducing malaria to areas where it may have been eliminated. War kills people; malaria kills people – when soldiers are infected a double dose of death potentially occurs