Documentation

The following documents describe the sample and methods used to construct the standards and present the final charts.

WHO Child Growth Standards: Methods and development: Length/height-for-age, weight-for-age, weight-for-length, weight-for-height and body mass index-for-age

WHO Child Growth Standards: Methods and development: Head circumference-for-age, arm circumference-for-age, triceps skinfold-for-age and subscapular skinfold-for-age

WHO Child Growth Standards: Methods and development: Growth velocity based on weight, length and head circumference Acta Paediatrica Supplement | Russian translation Chart catalogue | en español

Indicators

:: Length/height-for-age
:: Weight-for-age
:: Weight-for-length
:: Weight-for-height
:: Body mass index-for-age (BMI-for-age)
:: Head circumference-for-age
:: Arm circumference-for-age
:: Subscapular skinfold-for-age
:: Triceps skinfold-for-age
:: Motor development milestones :: Weight velocity
:: Length velocity
:: Head circumference velocity

Infection and transmission

Tuberculosis (TB) is a contagious disease. Like the common cold, it spreads through the air. Only people who are sick with TB in their lungs are infectious. When infectious people cough, sneeze, talk or spit, they propel TB germs, known as bacilli, into the air. A person needs only to inhale a small number of these to be infected.

Left untreated, each person with active TB disease will infect on average between 10 and 15 people every year. But people infected with TB bacilli will not necessarily become sick with the disease. The immune system “walls off” the TB bacilli which, protected by a thick waxy coat, can lie dormant for years. When someone’s immune system is weakened, the chances of becoming sick are greater.

• Someone in the world is newly infected with TB bacilli every second.
• Overall, one-third of the world’s population is currently infected with the TB bacillus.
• 5-10% of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life. People with HIV and TB infection are much more likely to develop TB.

Global and regional incidence

The World Health Organization (WHO) estimates that the largest number of new TB cases in 2005 occurred in the South-East Asia Region, which accounted for 34% of incident cases globally. However, the estimated incidence rate in sub-Saharan Africa is nearly twice that of the South-East Asia Region, at nearly 350 cases per 100 000 population.

It is estimated that 1.6 million deaths resulted from TB in 2005. Both the highest number of deaths and the highest mortality per capita are in the Africa Region. The TB epidemic in Africa grew rapidly during the 1990s, but this growth has been slowing each year, and incidence rates now appear to have stabilized or begun to fall.

In 2005, estimated per capita TB incidence was stable or falling in all six WHO regions. However, the slow decline in incidence rates per capita is offset by population growth. Consequently, the number of new cases arising each year is still increasing globally and in the WHO regions of Africa, the Eastern Mediterranean and South-East Asia.

Estimated TB Incidence, Prevalence and Mortality, 2005

^aIncidence - new cases arising in given period; prevalence - the number of cases which exist in the population at a given point in time.
^bSmear-positive cases are those confirmed by smear microscopy, and are the most infectious cases.
pop indicates population.

HIV and TB

HIV and TB form a lethal combination, each speeding the other’s progress. HIV weakens the immune system. Someone who is HIV-positive and infected with TB bacilli is many times more likely to become sick with TB than someone infected with TB bacilli who is HIV-negative. TB is a leading cause of death among people who are HIV-positive. In Africa, HIV is the single most important factor contributing to the increase in incidence of TB since 1990.

WHO and its international partners have formed the TB/HIV Working Group, which develops global policy on the control of HIV-related TB and advises on how those fighting against TB and HIV can work together to tackle this lethal combination. The interim policy on collaborative TB/HIV activities describes steps to create mechanisms of collaboration between TB and HIV/AIDS programmes, to reduce the burden of TB among people and reducing the burden of HIV among TB patients.

Drug-resistant TB

Until 50 years ago, there were no medicines to cure TB. Now, strains that are resistant to a single drug have been documented in every country surveyed; what is more, strains of TB resistant to all major anti-TB drugs have emerged. Drug-resistant TB is caused by inconsistent or partial treatment, when patients do not take all their medicines regularly for the required period because they start to feel better, because doctors and health workers prescribe the wrong treatment regimens, or because the drug supply is unreliable. A particularly dangerous form of drug-resistant TB is multidrug-resistant TB (MDR-TB), which is defined as the disease caused by TB bacilli resistant to at least isoniazid and rifampicin, the two most powerful anti-TB drugs. Rates of MDR-TB are high in some countries, especially in the former Soviet Union, and threaten TB control efforts.

While drug-resistant TB is generally treatable, it requires extensive chemotherapy (up to two years of treatment) with second-line anti-TB drugs which are more costly than first-line drugs, and which produce adverse drug reactions that are more severe, though manageable. Quality-assured second-line anti-TB drugs are available at reduced prices for projects approved by the Green Light Committee.

The emergence of extensively drug-resistant (XDR) TB, particularly in settings where many TB patients are also infected with HIV, poses a serious threat to TB control, and confirms the urgent need to strengthen basic TB control and to apply the new WHO guidelines for the programmatic management of drug-resistant TB.

The Stop TB Strategy, the Global Plan to Stop TB, 2006–2015 and targets for TB control

In 2006, WHO launched the new Stop TB Strategy. The core of this strategy is DOTS, the TB control approach launched by WHO in 1995. Since its launch, more than 22 million patients have been treated under DOTS-based services. The new six-point strategy builds on this success, while recognizing the key challenges of TB/HIV and MDR-TB. It also responds to access, equity and quality constraints, and adopts evidence-based innovations in engaging with private health-care providers, empowering affected people and communities and helping to strengthen health systems and promote research.

The six components of the Stop TB Strategy are:

• Pursuing high-quality DOTS expansion and enhancement. Making high-quality services widely available and accessible to all those who need them, including the poorest and most vulnerable, requires DOTS expansion to even the remotest areas. In 2004, 183 countries (including all 22 of the high-burden countries which account for 80% of the world’s TB cases) were implementing DOTS in at least part of the country.
• Addressing TB/HIV, MDR-TB and other challenges. Addressing TB/HIV, MDR-TB and other challenges requires much greater action and input than DOTS implementation and is essential to achieving the targets set for 2015, including the United Nations Millennium Development Goal relating to TB (Goal 6; Target 8).
• Contributing to health system strengthening. National TB control programmes must contribute to overall strategies to advance financing, planning, management, information and supply systems and innovative service delivery scale-up.
• Engaging all care providers. TB patients seek care from a wide array of public, private, corporate and voluntary health-care providers. To be able to reach all patients and ensure that they receive high-quality care, all types of health-care providers are to be engaged.
• Empowering people with TB, and communities. Community TB care projects have shown how people and communities can undertake some essential TB control tasks. These networks can mobilize civil societies and also ensure political support and long-term sustainability for TB control programmes.
• Enabling and promoting research. While current tools can control TB, improved practices and elimination will depend on new diagnostics, drugs and vaccines.

The strategy is to be implemented over the next 10 years as described in The Global Plan to Stop TB, 2006–2015. The Global Plan is a comprehensive assessment of the action and resources needed to implement the Stop TB Strategy and to achieve the following targets:

• Millennium Development Goal (MDG) 6, Target 8: Halt and begin to reverse the incidence of TB by 2015
• Targets linked to the MDGs and endorsed by the Stop TB Partnership:
  • by 2005: detect at least 70% of new sputum smear-positive TB cases and cure at least 85% of these cases
  • by 2015: reduce TB prevalence and death rates by 50% relative to 1990
  • by 2050: eliminate TB as a public health problem (1 case per million population)

Progress towards targets

In 2005, an estimated 60% of new smear-positive cases were treated under DOTS – just short of the 70% target.

Treatment success in the 2004 DOTS cohort of 2.1 million patients was 84% on average, close to the 85% target. However, cure rates in the African and European regions were only 74%.

The 2007 WHO report Global TB Control concluded that both the 2005 targets were met by the Western Pacific Region, and by 26 individual countries (including 3 of the 22 high-burden countries: China, the Philippines and Viet Nam.

The global TB incidence rate had probably peaked in 2005, and if the Stop TB Strategy is implemented as set out in the Global Plan, the resulting improvements in TB control should halve prevalence and death rates in all regions except Africa and Eastern Europe by 2015.

RELATED LINKS

Global tuberculosis control - surveillance, planning, financing

For more information contact:

WHO Media centre
Telephone: +41 22 791 2222
E-mail: mediainquiries@who.int

Glenn Thomas - Communication Officer
Stop TB, WHO
Mobile phone: +41 79 509 0677
E-mail: thomasg@who.int

The heart is a muscle. It pumps oxygen-rich blood to all parts of the body. When you have heart failure, the heart can’t pump as well as it should. Blood and fluid may back up into the lungs, and some parts of the body don’t get enough oxygen-rich blood to work normally. These problems lead to the symptoms you feel.

When You Have Heart Failure

Because of heart failure, not enough blood leaves the heart with each beat. There are two types of heart failure. Both affect the ventricles’ ability to pump blood. You may have one or both types.

Systolic heart failure: The heart muscle becomes weak and enlarged. It can’t pump enough blood forward when the ventricles contract. Ejection fraction is lower than normal.	Diastolic heart failure: The heart muscle becomes stiff. It doesn’t relax normally between contractions, which keeps the ventricles from filling with blood. Ejection fraction is often in the normal range.

How Heart Failure Affects Your Body

When the heart doesn’t pump enough blood, hormones (body chemicals) are sent to increase the amount of work the heart does. Some hormones make the heart grow larger. Others tell the heart to pump faster. As a result, the heart may pump more blood at first, but it can’t keep up with the ongoing demands. So, the heart muscle becomes more damaged. Over time, even less blood is pumped through the heart. This leads to problems throughout the body.

Raquel Escrig, MD^a, Luis Arruza, MD^b, Isabel Izquierdo, MD^a, Gema Villar, MD^a, Pilar Sáenz, MD^b, Ana Gimeno, MD^a, Manuel Moro, PhD, MD^b and Máximo Vento, PhD, MD^a

^a Neonatalogy Service, La Fe Infant-Maternal University Hospital, Valencia, Spain
^b Neonatalogy Service, University Clinical Hospital San Carlos, Complutense University, Madrid, Spain

OBJECTIVE. Extremely low gestational age neonates have very low oxygen saturation in utero and an immature antioxidant defense system. Abrupt increases in oxygen saturation after birth may cause oxidative stress. We compared achievement of a targeted oxygen saturation of 85% at 10 minutes of life when resuscitation was initiated with low or high fractions of inspired oxygen and levels were adjusted according to preductal pulse oxygen saturation values. METHODS. A prospective, randomized, clinical trial was performed in 2 level III neonatal referral units. Patients of 28 weeks of gestation who required active resuscitation were randomly assigned to the low-oxygen group (fraction of inspired oxygen: 30%) or the high-oxygen group (fraction of inspired oxygen: 90%). Every 60 to 90 seconds, the fraction of inspired oxygen was increased in 10% steps if bradycardia occurred (<100 beats per minute) or was decreased in similar steps if pulse oxygen saturation reached values of >85%. Preductal pulse oxygen saturation was continuously monitored.

RESULTS. The fraction of inspired oxygen in the low-oxygen group was increased stepwise to 45% and that in the high-oxygen group was reduced to 45% to reach a stable pulse oxygen saturation of 85% at 5 to 7 minutes in both groups. No differences in oxygen saturation in minute-to-minute registers were found independent of the initial fraction of inspired oxygen used 4 minutes after cord clamping. No differences in mortality rates in the early neonatal period were detected.

CONCLUSIONS. Resuscitation can be safely initiated for extremely low gestational age neonates with a low fraction of inspired oxygen (30%), which then should be adjusted to the infant’s needs, reducing the oxygen load to the neonate.

Abbreviations: SpO₂—arterial oxygen by pulse oximetry • HR—heart rate • CPAP—continuous positive airway pressure • FIO₂—fraction of inspired oxygen

Alexander G. Fiks, MD, MSCE^a,b,c, Kenya F. Hunter, MPH^b,c, A. Russell Localio, PhD^d, Robert W. Grundmeier, MD^a,c and Evaline A. Alessandrini, MD, MSCE^a,b,c

^a Pediatric Research Consortium
^b Pediatric Generalist Research Group, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania; Departments of
^c Pediatrics
^d Biostatistics and Epidemiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania

OBJECTIVE. We assessed the impact of immunization at sick visits on subsequent and overall well-child care. METHODS. We performed a retrospective cohort study using electronic health record data from 4 urban practices affiliated with an academic medical center. Participants included all children born between September 1, 2003, and July 31, 2004, with a visit at a study practice before 6 weeks of age and 1 sick visit (n = 1675). The main outcome measures were (1) attendance at a well-child visit within 60 days after an index sick visit by children due for vaccines and preventive care and (2) the overall number of well-child visits kept by children between 6 weeks and 13 months of age.

RESULTS. Among all demographic and health-related factors considered, immunization receipt at a sick visit was associated most strongly with decreased subsequent well-child care. Among children already delayed (late) for vaccines, 31% returned for well-child care if immunizations were given at eligible sick visits, compared with 47% of those who received no vaccines (risk difference, with adjustment for covariates: –16%). Among those without immunization delay, 42% of children who received vaccines returned for well-child care, compared with 73% of those who received no vaccines (risk difference: –31%). Although 5 well-child visits are recommended, children with no immunizations at sick visits had an adjusted predicted number of 3.8 well-child visits, those with 1 sick visit with immunizations had 3.3 visits, and those with 2 sick visits with immunizations had 2.8 visits between 6 weeks and 13 months of age.

CONCLUSIONS. Immunization at sick visits was associated with decreased rates of well-child care, especially among those without previous vaccine delay. This strong association between immunization at sick visits and well-child care should be considered in any plan to restructure pediatric preventive care.

Vaccine Preventable Illnesses