Posts or Comments 01 March 2021

Monthly Archive for "January 2017"



IPTp &ITNs &Malaria in Pregnancy Bill Brieger | 27 Jan 2017

Malaria in Pregnancy Progress in Nigeria – the 2015 Malaria Indicator Survey

With an eye toward the future Nigeria’s National Malaria Control Program also refers to itself as the National Malaria Elimination Program (NMEP). Given that Nigeria has the highest burden of malaria in Africa, along with around one-quarter of sub-Saharan Africa’s population, the elimination goal will take a lot of work.

Recently the 2015 Malaria Information Survey (MIS) for Nigeria was released and gives a perspective on how far we have some and how far we need to go. We will focus on malaria in pregnancy (MIP) interventions today.

Intermittent Preventive Treatment for pregnant women (IPTp) using sulfadoxine-pyrimethamine (SP) remains the key MIP intervention due to the high and stable malaria transmission that still persists. There is always a challenge in delivering health interventions that require multiple contacts, and IPTp is not exception. The difficulty in achieving two doses when that was policy was clear. Now that WHO recommends monthly dosing from the second trimester forward (giving the possibility of 3, 4 or more doses), the service delivery challenge is heightened.

We can see in the attached graph from the MIS report that while there is progress, it remains well below the 2010 Roll back malaria Target of 80%. Part of the problem resides in the fact that the 2013 DHS showed only 61% of pregnant women attended even one antenatal care visit while 51% attended four or more.

The second lesson of the graph is missed opportunities. There is a gap between IPTp1 coverage of 37% and at least one ANC visit of 61%. Granted, 18% of women made their first visit in the first trimester when SP is not given, but not all of those stopped ANC then. The next evidence of missed opportunities is the gap between IPTp1 and IPTp2, almost a quarter of women who started IPTp did not get a second dose. We cannot say that the women’s own attendance gaps account for all the missed opportunities; some are likely due to health systems weaknesses such as stock-outs and health staff attention.

Key demographic factors are linked to receiving two or more IPTp doses. Only 30% or rural women received two or more compared to 50% of urban. There was a steady progression from 21% of the poorest women to 55% of those in the highest wealth quintile. A second chart also shows variation by section of the country. These access gaps are why we have advocated for supplementary distribution of IPTp through trained community health workers.

Use of insecticide treated bed nets by pregnant women shows a similar increase over time. The dip in 2013 probably related to fact that mass campaigns had occurred between 2009 and 2011 and thus by the time of the survey some nets had become damaged and abandoned. A major challenge in achieving net coverage is NOT relying on periodic distribution campaigns only, but ensuring regular and reliable supplies during routine services such as antenatal care. This again is a health systems problem that must be solved.

Net access is not only a health systems issue, bit may be factor of internal household dynamics. Even when the household possesses nets, only 63% of pregnant women therein slept under one the night before the survey. Community education needs strengthening – more than just telling people what to do but involving them is solving the problems of net use.

So as mentioned earlier, progress is being made, but more effort is needed. We are especially concerned because of the precariousness of global financial support for disease control. Nigeria needs to strategize how it can meet its own needs in protecting pregnant women and their unborn children from malaria, disability and death.

Dengue &Mosquitoes &Surveillance &Urban Bill Brieger | 09 Jan 2017

Malaria, Dengue, Mosquitoes – evolving in the urban environment

As the world increasingly urbanizes, we need to address the role of urban ecosystems and the evolution of disease vectors and organisms.  Marina Alberti and colleagues explained that …

“Recent studies show that cities might play a major role in contemporary evolution by accelerating phenotypic changes in wildlife, including animals, plants, fungi, and other organisms. Many studies of ecoevolutionary change have focused on anthropogenic drivers, but none of these studies has specifically examined the role that urbanization plays in ecoevolution or explicitly examined its mechanisms.”

In their own study they looked at “five types of urban disturbances including habitat modifications, biotic interactions, habitat heterogeneity, novel disturbances, and social interactions.” The researchers learned that, “clear urban signal; rates of phenotypic change are greater in urbanizing systems compared with natural and nonurban anthropogenic systems.” They concluded that there is need to continually “uncover insights for maintaining key ecosystem functions upon which the sustainability of human well-being depends.”

Of particular concern in the area of tropical health are the unique urban manifestations of diseases like yellow fever, dengue and malaria. Although Zika virus, for example, was first discovered in forests, it has adapted to an urban cycle involving humans and domestic mosquito vectors in tropical areas where dengue is endemic. Musso and Gubler in their review further explain that although there may be sylvatic cycles of Dengue, “Arboviruses such as DENV have adapted completely to humans and can be maintained in large tropical urban centers in a mosquito-human-mosquito transmission cycle that does not depend on nonhuman reservoirs.”

Weaver et al. note that Zika in spreading to Asia, “emerged on multiple occasions into urban transmission cycles involving Aedes (Stegomyia) spp. Mosquitoes.” In addition it can be hypothesized that phenotypic changes in Asian lineage ZIKV strains made rare disease outcomes such as congenital microcephaly and Guillain-Barré more common and visible.

According to Estelle Martin and co-researchers, “Puerto Rico, a major metropolitan center in the Caribbean, has experienced increasingly larger and clinically more severe epidemics following the introduction of all four dengue serotypes.” They found that Dengue serotype 4 replaced earlier strains and that “this epidemic strain progressed rapidly, suggesting that the epidemic strain was more fit, and that natural selection may have acted on these mutations to drive them to fixation.”

In addition to virus evolution, mosquito changes have been documented by Caroline Louise and colleagues in “One of the world’s largest urban agglomerations infested by Ae. aegypti … the Brazilian megalopolis of Sao Paulo.”  They detected microevolution despite a short observational period and stress the implications of the “rapid evolution and high polymorphism of this mosquito vector on the efficacy of control methods.”

“The adaptation of malaria vectors to urban areas is becoming a serious challenge for malaria control,” is a major concern of Antonio-Nkondjio and co-workers. They found, “rapid evolution of pyrethroid resistance in vector populations from the cities of Douala and Yaoundé,” Members of this team also learned that the M form of Anopheles gambiae predominated in the centre of urban agglomerates in Cameroon. Previously it was known that larval habitats polluted with decaying organic matter as found in densely populated urban agglomerates, were unsuitable for Anopheles gambiae. The recent study showed that the “M form showed greater tolerance to ammonia (arising from organic matter) compared to the S form. This trait may be part of the physiological machinery allowing forest populations of the M form to colonize polluted larval habitats.”

The evolutionary response of vectors and disease organisms to urban environments needs continued monitoring. Urban disease control and elimination efforts must adapt to such adaptations in the disease process.