Monday, September 8, 2014

Home

I left Tanzania last Saturday evening, arrived home Sunday afternoon, and was back at work Tuesday morning. Since I returned home a week ago, Andrew has taken a lot of time out of his busy schedule to hang out with me.

This was my fourth trip to Africa, my third trip as a nurse, but my first trip as a husband and father. It was also the first time I had spent more than a week away from home since Andrew was born. Fortunately, I had access to a high-speed Internet connection and was able to Skype Holly and Andrew almost every day.
 
Andrew and his granddad Rollosson talking to me via Skype
It's interesting to consider that during my first trip to Africa in the late 1980s, most people in the U.S. had not heard of the Internet. When I was in Ethiopia, we had to drive an hour to the next city to plug our laptop into a phone line so we could send and receive Email over a dial-up connection. Now, I not only had high-speed Internet in a rural area of sub-Saharan Africa, cell phones seem to be ubiquitous.

Being able to talk to Holly and Andrew and hear my little boy laugh made the separation easier for me but, after a month, all I wanted to do was come home to my wife and child. I think Andrew got tired of the daddy-on-the-computer routine. The last week or so he would look for me behind the monitor and under the table.

I left bedside nursing for public health five years ago. The focus of my work shifted from helping people recover from injuries and illness to preventing illness. In addition to stepping back into my role as a neuroscience nurse, I was also working in a setting where there were inadequate resources to care for severely injured patients and where I expected to see people die who might have survived if they had received care in the U.S. I knew that I wouldn't be able to fix all of the problems that I saw and that the best I could do was share what I know with my Tanzanian colleagues so that they are better able to care for their patients.
 
Teaching the Glasgow Coma Scale to student nurses
I gave a presentation on care of patients with spinal cord injuries the day before I left Haydom. I began my talk by congratulating the hospital staff for providing high-quality care to their community. I ended my presentation with Proverbs 27:17, "As iron sharpens iron, so one person sharpens another," and thanked them for sharpening me.

My work at Haydom was challenging, but I'm glad that I had this opportunity. I will do it again, and I encourage my colleagues to seek opportunities to work in a developing country.
 
 
Out of all of the health workers I khave known who have worked in Africa, I can't think of one who has been there only once. There is something about working in Africa that pulls us back.
 
 
Africa is full of surprising beauty. Even in the semi-arid climate of East Africa, there is beauty in the iridescent colors that seem to spring unexpectedly from the landscape. More importantly, there is the beauty of the human spirit; the joy of living in spite of hardship.
 

Outreach: I spent the day in the shade of acacia trees weighing babies and checking pregnant women's blood pressure
Spending time away from the noise and distractions and the pace of living in a wealthy industrialized country gives me an opportunity to see the world from a different perspective. I return home with a recognition of the triviality of many of the things that occupy our minds and our time and an appreciation that some of the things for which we have the luxury of taking for granted are what is truly precious.


Friday, August 8, 2014

Greetings from Tanzania!

I am currently teaching nurses at Haydom Lutheran Hospital in Tanzania.

Although this is my first trip to Tanzania, this is my fourth trip to Africa and my third time on the continent working as a nurse. I decided to become a nurse after my first trip to Africa in 1988-89.

I think it's easy to come to developing country and see only poverty and suffering. It's easy to feel frustration and a sense of futility when confronted with the problems people living in an impoverished part of the world face. Here, problems that are relatively rare in the U.S. are common. I have seen expatriate health care workers become pessimistic and angry when simple solutions to problems seem to be unavailable in rural Africa.

I am not immune to those feelings, however, I also see here resourcefulness in a resource-poor setting, the beauty of humanity and Creation, and, most importantly, hope.

Here, a mother of ten children can have surgery to repair her torn uterus and receive a safe blood transfusion rather than bleed to death or be infected with a blood-borne pathogen,

Unit of blood tested for HIV, hepatitis B, and hepatitis C

 a person with a spinal cord injury or a stroke can learn to walk again,


myelomeningoceles are repaired,


tuberculosis is cured,



and broken bones are repaired.



Here, people who would have died without the medical and surgical services provided survive, disabilities are minimized, and people return home to their families.

My special thanks to Karen March, Neuroscience Clinical Nurse Specialist, mentor, and friend, who facilitated my visit to Haydom Lutheran Hospital.


Karen buying a SIM card for her cell phone from a vendor in Haydom


Sunday, July 27, 2014

Demographic transition: do vaccines reduce fertility?


First, what is fertility? To most people, fertility is the ability to have children; the opposite of infertility. To demographers and epidemiologists, fertility is the number of children a person has. According the U.S. Census Bureau, fertility is the number of children ever born to a person (referring to the number of live births). "Typically it is asked of women age 15 to 50, or women of all ages but some surveys ask men how many children they have fathered." A fertility rate is the number of children born in a population over a period of time, usually per 1,000 people per year. To demographers and epidemiologists, the ability to have children in known as fecundity rather than fertility.

In his book, The End of Poverty, Jeffery Sachs wrote, "I have been asked dozens of times if help for Africa would ultimately backfire in an even greater population explosion. Would greater child survival rates not translate into more adult hunger and suffering?"

I've been asked similar questions about my interest in tropical medicine and my volunteer work in Africa. Sachs goes on to discuss the demographic transition, a phenomenon that has occurred in every industrialized country and is occurring in developing countries; that is, as standards of living improve, people have fewer children.

There are a several theories about why the demographic transition occurs. The primary theory links decreasing fertility to decreases in child mortality; parents have fewer children when more of their children survive to adulthood.

We can see this occurring today. In the graph below, I've used World Bank data from 2012 to plot child mortality rates (the number of deaths of children under 5 years of age per 1,000 population per year) against fertility rates. Each dot represents a country. In countries in which child mortality is low, women have fewer children. In countries with high death rates for children under 5 five years of age, fertility rates are higher.

 

Childhood vaccines are associated with improved child survival. Measles immunization has been shown to decrease all cause mortality. In the graph below I've plotted mortality of children less than 5 years of age against the percent of children 12 to 23 months of age who have received measles vaccines. Under 5 mortality is higher in countries with lower measles immunization coverage than in countries with high measles vaccine coverage.

 

Of course, there are a number of other factors associated with both decreasing child mortality and decreasing fertility including higher costs of raising a child (e.g., education), transitioning from agricultural to manufacturing markets and urbanization (people who live in cities tend to have fewer children than those living in rural areas), more women working outside of the home, changes in social norms, and, of course, access to contraception.

Although there have been improvements in the prevention and treatment of malaria, most malaria deaths occur in children under 5 years in sub-Saharan Africa. This is one of the reasons fertility remains high in Africa.

In 2010, Bill Gates made a passing reference to the demographic transition during a TED Talk on energy and climate:

First, we've got population. The world today has 6.8 billion people. That's headed up to about nine billion. Now, if we do a really great job on new vaccines, health care, reproductive health services, we could lower that by, perhaps, 10 or 15 percent, but there we see an increase of about 1.3.

Gates had discussed the demographic transition in the Bill and Melinda Gates Foundation 2009 annual letter:

Two things caused this huge reduction in the death rate. First, incomes went up, and with that increase, nutrition, medical care, and living conditions improved. The second factor is that even where incomes did not go up, the availability of life-saving vaccines reduced the number of deaths. For example, measles accounted for 4 million children’s deaths in 1990, but fewer than 250,000 in 2006.

A surprising but critical fact we learned was that reducing the number of deaths actually reduces population growth. Chart 3 shows the strong connection between infant mortality rates and fertility rates. Contrary to the Malthusian view that population will grow to the limit of however many kids can be fed, in fact parents choose to have enough kids to give them a high chance that several will survive to support them as they grow old. As the number of kids who survive to adulthood goes up, parents can achieve this goal without having as many children.


Bill and Melinda Gates Foundation, 2009

Unfortunately, Gates' TED Talk comments were misinterpreted by several people in the blogosphere to mean that vaccines cause infertility.

To answer the question in the title of this post, "do vaccines reduce fertility?" I will violate Betteridge's law of headlines and say, yes, vaccines reduce fertility, but not in the way some people would like you to believe.

 
References:

Bloom, D. E., Canning, D., & Weston, M. (2005). The value of vaccination. World Economics, 6(3), 15-39.

Brauner-Otto, S., Axinn, W., & Ghimire, D. (2007). The spread of health services and fertility transition. Population Studies Center Research Report 07-619. http://www.psc.isr.umich.edu/pubs/pdf/rr07-619.pdf.

Conley, D., McCord, G. C., & Sachs, J. D. (2007). Africa's lagging demographic transition: evidence from exogenous impacts of malaria ecology and agricultural technology. National Bureau of Economic Research Working Paper Series No. 12892. http://www.nber.org/papers/w12892.

Gates, B. (2009). Bill and Melinda Gates Foundation annual letter 2009. http://www.gatesfoundation.org/who-we-are/resources-and-media/annual-letters-list/annual-letter-2009.


Greenwood, J. & Sesharid, A. (2001). The U.S. demographic transition. AEA Papers and Proceedings, 92(2), 153-159. http://www.econ.wisc.edu/~aseshadr/publication_pdf/usdt.pdf.

Newson, L., Postmes, T., Lea, S. E. G., & Webley, P. (2005). Why are modern families small? Toward an evolutionary and cultural explanation for the demographic transition. Personality and Social Psychology Review, 9(4), 360-373.

Omran, A R. (1971). The epidemiologic transition. Milbank Memorial Fund Quarterly, 49(4), 509-538.

Sachs, J. D. (2005). The end of poverty: economic possibilities for our time. New York: The Penguin Press.

van den Ent, M. M. V. X., Brown, D. W., Hoelstra, E. J., Christie, A., & Cochi, S. L. (2011). Measles mortality reduction contributes substantially to reduction of all cause mortality among children less than five years of age, 1990-2008. Journal of Infectious Diseases, 204(Supple. 1), S18-S23. http://jid.oxfordjournals.org/content/204/suppl_1/S18.long.

World Bank. (2014). Data. http://data.worldbank.org.
 

 

Sunday, July 13, 2014

Modified measles


Happy birthday Andrew!
 

 
Our little boy is two years old today. Seeing Andrew grow up has been one of the greatest joys of my life. I have been enthralled by watching our little scientist learn about the world. Watching him learn new skills and challenge himself has made me a very proud daddy!


Measles vaccine is highly effective; so effective that high immunization coverage has resulted in the elimination of measles from the U.S. Nevertheless, a small proportion of people who receive measles vaccine do not develop an immune response sufficient to prevent infection. This is known as primary vaccine failure. There is evidence that measles antibody levels (titers) wane over time allowing some people to become susceptible to measles. Infection in a person who initially developed an adequate immune response to the vaccine but later became susceptible is called secondary vaccine failure.

One of the factors that contributes to waning immunity to measles is the loss of natural boosting. In the past, people in the U.S. were periodically exposed to measles virus during epidemics. Since measles has been eliminated from the U.S., exposure to the virus in this country has become rare.

Secondary measles vaccine failure is more likely to occur with intense exposure to the measles virus. This can occur during an outbreak or among household contacts of a person with measles. For this reason, it's not unusual to find vaccinated people with measles during an outbreak.

Modified measles, measles in a vaccinated person, is much milder than measles in an unvaccinated person; fever and rash are less severe and a person with modified measles is much less likely to develop complications of measles than an unvaccinated person with measles. In contrast to unvaccinated people with measles, vaccinated people who develop modified measles have high avidity antibodies, meaning, their antibodies are mature and bind tightly to the virus.

People with modified measles are also much less likely to infect other people than unvaccinated people with measles. There have been numerous cases of modified measles in previously vaccinated people with no evidence of transmission to close contacts reported in the medical literature. There have even been reports of vaccinated doctors who developed modified measles but did not infect their patients (Lee et al., 2008; Rota et al., 2011).

Earlier this year, Jennifer Rosen and colleagues published the first report of transmission of measles from a previously vaccinated person. In 2011, a 22-year-old woman in New York City who had received two doses of MMR as a child who developed measles. Out of 88 people who had contact with her, 4 people developed measles. One was her coworker and the other three were health care workers at a clinic. Two of the secondary cases had received two doses of MMR as children and the other two had previous evidence of immunity (positive immunoglobulin G titer). None of the contacts to the four secondary cases developed measles. The authors wrote, "this outbreak probably represents a series of rare events" and that it "does not justify a change in current measles control and elimination strategies."

References:

Centers for Disease Control and Prevention. (2013). Prevention of measles, rubella, congenital rubella syndrome, and mumps, 2013: summary recommendations of the Advisory Committee on Immunization Practices (ACIP). Morbidity and Mortality Weekly Report, 62(4), 1-34. http://www.cdc.gov/mmwr/preview/mmwrhtml/rr6204a1.htm.

Gershon, A. A. (2009). Measles virus (rubeola). In G. L. Mandell, J. E. Bennett, & R. Dolin (Eds.). Mandell, Douglas, and Bennett’s principles and practice of infectious diseases. (7th Ed.) [Electronic version].

Hickman, C. J., Hyde, T. B., Sowers, S. B., Mercader, S., McGrew, M., Williams, N. J. et al. (2011). Laboratory characterization of measles virus infection in previously vaccinated and unvaccinated individuals. Journal of Infectious Diseases, 204(Suppl. 1), S549-S558. http://jid.oxfordjournals.org/content/204/suppl_1/S549.full.

Lee, N. Y., Lee, H. C., Chang, C. M., Wu, C. J., Ko, N. Y., Ko, C. (2008). Modified measles in a healthcare worker after return from travel. Infection Control and Hospital Epidemiology, 29(4), 380-381. http://www.jstor.org/stable/10.1086/529031.

Mercader, S., Garcia, P., & Bellini, W. J. (2012). Measles virus avidity assay for use in classification of measles vaccine failure in measles elimination settings. Clinical and Vaccine Immunology, 19(11), 1810-1817. http://cvi.asm.org/content/19/11/1810.

Mitchell, P., Turner, N., Jennings, L., & Dong, H. (2013). Previous vaccination modifies both the clinical disease and immunological features in children with measles. Journal of Primary Health Care, 5(2), 93-98. http://www.ncbi.nlm.nih.gov/pubmed/23748389.

Rosen, J. B., Rota, J. S., Hickman, C. J., Sowers, S. B., Mercader, S., Rota, P. A. et al. (2014). Outbreak of measles among persons with prior evidence of immunity, New York City, 2011. Clinical Infectious Diseases, 58(9), 1205-1210. http://cid.oxfordjournals.org/content/early/2014/02/27/cid.ciu105.

Rota, J. S., Hickman, C. J., Sowers, S. B., Rota, P. A., Mercader, S., & Bellini, W. J. (2011). Two case studies of modified measles in vaccinated physicians exposed to primary measles cases: high risk of infection but low risk of transmission. Journal of Infectious Diseases, 204(Suppl. 1), S559-S563. http://jid.oxfordjournals.org/content/204/suppl_1/S559.full.

 

Sunday, June 29, 2014

Measles outbreaks in Washington State



Andrew received a dose of measles, mumps, rubella, and varicella (MMRV) vaccine at 12 months of age.


This past week we saw the first case of measles in a Pierce County resident since 2006.

Our newest case is a 13-month-old child that was seen in an emergency department (ED) in Tacoma on June 10th for an unrelated condition. Unfortunately, there was a King County resident in the ED who had contracted measles from an unvaccinated person who had returned to the U.S. on May 26th. While he was contagious, the 13-month-old Pierce County resident was seen in the Mary Bridge/Tacoma General ED on June 22nd and June 24th and at the St Joseph ED June 24th – 25th.

My colleagues and I at the Tacoma-Pierce County Health Department have been anxiously watching previous outbreaks of measles in Washington State and preparing for an outbreak in our jurisdiction.

On March 29th of this year, a Whatcom County resident with measles travelled to King and Pierce counties. That person's infection was linked to a large outbreak in Fraser Valley, British Columbia. Fortunately, no secondary cases of measles from those exposures were reported in either Pierce or King county.
 
The incubation period for measles is usually 1 to 3 weeks. A person with measles becomes contagious 4 days before developing a rash, that is, before that person has any signs or symptoms of measles.

For people who have not been vaccinated or those whose immunization status is unknown, measles vaccine can be given up to 72 hours after exposure to prevent measles or reduce the severity of the disease. For people who cannot receive measles vaccine or for people at high risk of complications from measles, immune globulin can be used up to 6 days after exposure to reduce the severity of disease.

In the United States, measles vaccine is usually not given to children less than one year of age. This is because maternal antibodies, which partially protect babies from measles, can interfere with the immune response to measles vaccine. Measles vaccine can be given as early as 6 months of age if a baby has been exposed to measles or in preparation for travel to a country in which measles is endemic. A dose given before 12 months of age does not count as that child's first dose, so that child should receive a dose at 12 to 15 months of age and 4 to 6 years of age.

The health department sent an alert to health care providers in Pierce County asking them to be on the lookout for cases of measles. Health care providers are required by state law to immediately notify the health department of suspected cases of measles. My colleagues and I at the health department are on call 24/7 to respond to those notifications.

Fortunately, most school children in Pierce County have received 2 doses of measles, mumps, and rubella (MMR) vaccine. The vaccine provides life-long protection against measles to more than 99% of people who receive two doses.

My previous posts on measles and related topics:
·       Measles
·       Attack ratios

Center for Disease Control and Prevention (CDC) information on measles and measles vaccine:
·       Measles (Rubeola)
·       Measles Vaccination
·       Pink Book

Reference:

Centers for Disease Control and Prevention. (2013). Prevention of measles, rubella, congenital rubella syndrome, and mumps, 2013: summary recommendations of the Advisory Committee on Immunization Practices (ACIP). Morbidity and Mortality Weekly Report, 62(4), 1-34. http://www.cdc.gov/mmwr/preview/mmwrhtml/rr6204a1.htm.

 

 

 

Sunday, June 8, 2014

Travel immunizations update

 
 
This summer I will spend a month teaching nurses in Tanzania. In preparation for my trip, I'm reviewing travel medicine recommendations and would like to address some developments since my previous post on travel immunizations.
 
In previous years, the Centers for Disease Control and Prevention (CDC) reported that most of the cases of measles in the United States are associated with importations from countries where measles immunization coverage is low. In the first 5 months this year, there have been more cases of measles in this country than in any year since 2000 when measles was eliminated from the U.S.
 
 
 
 
Once again, most of those cases are associated with importations, nearly half of which were travelers returning from the Philippines, and most of the cases are unvaccinated people. There has also been a large outbreak of measles in Fraser Valley, B.C. that centered on a community with low measles immunization coverage and was associated with importation from the Netherlands. Here in Washington State there were several cases associated with the Fraser Valley outbreak in Whatcom County. One individual traveled to King and Pierce Counties. Fortunately, there were no known cases from those exposures.
 
 
On May 5th 2014 the Director General of the World Health Organization (WHO) declared ongoing international transmission of wild polio virus (WPV) a public health emergency and issued temporary requirements for polio immunization for travel between countries that are currently exporting WPV.
 
WHO requested the following countries ensure that long-term visitors (more than 4 weeks) show documentation of a polio vaccine booster between 4 weeks and 12 months prior to departure (countries currently exporting WPV):
 
·       Cameroon
·       Pakistan
·       Syria
 
WHO requested the following countries encourage long-term visitors (more than 4 weeks) to receive a polio vaccine booster between 4 weeks and 12 months prior to departure (countries with active WPV transmission but not currently exporting WPV):
 
·       Afghanistan
·       Equatorial Guinea
·       Ethiopia
·       Iraq
·       Israel
·       Nigeria
·       Somalia
 
These are measures are temporary and may change.
 
The CDC maintains its recommendation the travelers to polio-affected countries are fully vaccinated against polio and that adults receive a one-time polio vaccine booster.
 
Yellow fever
As I discussed in my previous post, International Health Regulations (IHR) require yellow fever vaccanation for travel between certain countries. The requirement includes booster doses of yellow fever vaccine every 10 years.
 
Last year the WHO Strategic Advisory Group of Experts (SAGE) on immunizations examined the effectiveness and duration of immunity of yellow fever vaccine and concluded that, for healthy people, immunity to yellow fever from a single dose of vaccine is probably life-long and that booster doses are not required. Further research is needed to determine in the efficacy and safety of yellow fever vaccine in certain populations including people who are immunocompromised and pregnant woman.
 
The current recommendations for booster doses of yellow fever vaccine every 10 years will remain in effect until June 2016 – long before I'm due for another dose.
 
Traveler's health
There are specific recommendations for each of the vaccines that I've discussed. For example, documentation of receipt of a yellow fever vaccine may only be required for persons traveling from an endemic country and may not be required for a person traveling directly from the United States. International Health Regulations require that yellow fever vaccine be administered at an authorized yellow vaccine clinic.
 
There are also specific contraindications and precautions for each of these vaccines.
 
In addition to required and recommended vaccines, there are other recommendations for travelers for health risks specific to endemic counties or areas within those countries.
 
 
Vaccine information
·       Measles
·       Polio
·       Yellow fever
 
Recommended reading
 
I'll miss you while I'm away, little man.
 
References
 
Centers for Disease Control and Prevention. (2000). Poliomyelitis prevention in the United States. Updated recommendations of the Advisory Committee on Immunization Practices (ACIP). Morbidity and Mortality Weekly Report, 49(5), 1-22. http://www.cdc.gov/mmwr/preview/mmwrhtml/rr4905a1.htm.
 
Centers for Disease Control and Prevention. (2009). Updated recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding routine poliovirus vaccination. Morbidity and Mortality Weekly Report, 58(30), 829-830. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5830a3.htm.
 
Centers for Disease Control and Prevention. (2013). Clinical update: yellow fever vaccine booster. http://wwwnc.cdc.gov/travel/news-announcements/yellow-fever-vaccine-booster.
 
Centers for Disease Control and Prevention. (2014). Guidance to U.S. clinicians regarding new WHO polio vaccination requirements for travel by residents of and long-term visitors to countries with active polio transmission. http://emergency.cdc.gov/han/han00362.asp.
 
Gastañaduy, P. A., Redd, S. B., Fiebelkorn, A. P., Rota, J. S., Rota, P. A., Bellini, W. J. et al. (2014). Measles – United States, January 1 – May 23, 2014. Morbidity and Mortality Weekly Report, 63(22), 496-499. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6322a4.htm.
 
Gotuzzo, E., Yactayo, S., & Córdova, E. (2013). Efficacy and duration of immunity after yellow fever vaccination: systematic review on the need for a booster every 10 years. American Journal of Tropical Medicine and Hygiene, 89(3), 434-444. http://www.ajtmh.org/content/89/3/434.long.
 
McLean, H. Q., Fiekelkorn, A. P., Temte, J. L., & Wallace, G. S. (2013). Prevention of measles, rubella, congenital rubella syndrome, and umps, 2013. Summary recommendations of the Advisory Committee on Immunization Practices. Morbidity and Mortality Weekly Report, 62(4), 1-34. http://www.cdc.gov/mmwr/preview/mmwrhtml/rr6204a1.htm.
 
Staples, J. E., Gershman, M., & Fischer, M. (2010). Yellow fever vaccine. Recommendations of the Advisory Committee on Immunization Practices (ACIP). Morbidity and Mortality Weekly Report, 59(7), 1-27. http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5907a1.htm.
 
World Health Organization. (2013). Meeting of the Strategic Advisory Group of Experts in immunizations, April 2013 – conclusions and recommendations. Weekly Epidemiological Review, 88(20), 201-216. http://www.who.int/wer/2013/wer8820.pdf.
 
World Health Organization. (2013). Vaccines and vaccination against yellow fever. Weekly Epidemiological Review, 88(27), 269-283. http://www.who.int/wer/2013/wer8827.pdf.
 
World Health Organization. (2014). WHO guidance for implementation of the IHR temporary recommendations under the IHR (2005) to reduce the international spread of polio. http://www.polioeradication.org/Portals/0/Document/Emergency/PolioPHEICguidance.pdf.
 
World Health Organization. (2014). Yellow fever vaccination booster. http://www.who.int/ith/updates/20140605/en.