Residency · Residency · Medicine Pediatrics
Global Child and Adult Health: Infectious Disease Priorities
Introduction
Infectious diseases remain the leading cause of morbidity and mortality in low- and middle-income countries (LMICs), disproportionately affecting children under five. While immunization and public health interventions have dramatically reduced deaths from vaccine-preventable diseases, pneumonia, diarrheal diseases, malaria, tuberculosis, and HIV continue to drive global health burden. Med-peds physicians with global health interests must understand the epidemiology, prevention, and management of these priority infections across the lifespan.
The Global Burden of Infectious Disease
| Disease | Annual Deaths (Children <5) | Annual Deaths (All Ages) | Key Prevention | First-Line Treatment |
|---|---|---|---|---|
| Pneumonia | ~700,000 | >2.5 million | PCV, Hib vaccine, zinc | Amoxicillin (non-severe); ampicillin + gentamicin (severe) |
| Diarrheal diseases | ~500,000 | ~1.5 million | Rotavirus vaccine, WASH | ORS + zinc supplementation |
| Malaria | ~400,000 | ~600,000 | RTS,S/R21 vaccine, ITNs, SMC | ACTs (uncomplicated); IV artesunate (severe) |
| Tuberculosis | ~200,000 | ~1.3 million | BCG (severe forms) | RIPE regimen |
| HIV/AIDS | ~80,000 | ~650,000 | PMTCT, PrEP | Dolutegravir-based ART |
Infectious diseases account for approximately 4 of the top 10 causes of death in LMICs. Under-5 mortality: ~5 million deaths annually; 50% are due to infectious causes. Leading infectious causes of child death: pneumonia (~700,000), diarrheal diseases (~500,000), malaria (~400,000 in children under 5) Tuberculosis: ~1.3 million deaths annually; leading single-agent infectious cause of death globally. HIV: ~650,000 deaths annually; pediatric HIV remains a major challenge with 1.7 million children living with HIV.
Pneumonia
Pediatric Pneumonia
Leading infectious cause of death in children under 5 worldwide. Major pathogens: Streptococcus pneumoniae, Haemophilus influenzae type b, RSV, influenza. Integrated Management of Childhood Illness (IMCI): WHO algorithm for community and health center-level diagnosis and treatment using respiratory rate, chest indrawing, and danger signs. Treatment: Oral amoxicillin for non-severe pneumonia; parenteral ampicillin plus gentamicin for severe pneumonia. Prevention: PCV13/15, Hib vaccine, and zinc supplementation reduce pneumonia incidence and mortality.
Adult Pneumonia
Leading infectious cause of hospitalization in adults globally. Community-acquired pneumonia pathogens vary by setting; S. pneumoniae remains the most common worldwide. TB must be considered in any adult with cough >2 weeks in high-prevalence settings. Pneumococcal vaccination and influenza vaccination are key adult preventive strategies. HIV-associated pneumonia: Pneumocystis jirovecii pneumonia (PCP) remains a major opportunistic infection.
Diarrheal Diseases
Second leading cause of death in children under 5; ~500,000 deaths annually. Key pathogens: Rotavirus, Cryptosporidium, Shigella, enterotoxigenic E. coli, cholera. Oral rehydration solution (ORS) is the cornerstone of treatment; has saved an estimated 50 million lives since introduction. Zinc supplementation: 10-20 mg/day for 10-14 days reduces duration and severity; WHO/UNICEF recommendation. Rotavirus vaccine: Has dramatically reduced rotavirus hospitalizations and deaths where introduced. In adults, diarrheal diseases in LMICs are commonly due to contaminated water and food; cholera outbreaks affect all ages. WASH interventions (Water, Sanitation, and Hygiene) are critical population-level prevention strategies.
Malaria
Plasmodium falciparum causes the vast majority of malaria deaths; sub-Saharan Africa bears >90% of burden. Most deaths occur in children under 5; severe malaria presents with cerebral malaria, severe anemia, respiratory distress. Diagnosis: Rapid diagnostic tests (RDTs) and thick/thin blood smears. Treatment: Artemisinin-based combination therapy (ACT) is first-line for uncomplicated falciparum malaria; IV artesunate for severe malaria. RTS,S/AS01 (Mosquirix) and R21/Matrix-M: WHO-recommended malaria vaccines for children in endemic areas. Chemoprevention: Seasonal malaria chemoprevention (SMC) with SP-amodiaquine for children in the Sahel; IPTp with sulfadoxine-pyrimethamine for pregnant women. Adults in endemic areas develop partial immunity; malaria in non-immune travelers is a medical emergency.
Tuberculosis
Pediatric TB
1.3 million children develop TB annually; ~200,000 die. Diagnosis is challenging: children often have paucibacillary disease with negative sputum smears. Diagnostic tools: clinical scoring systems, tuberculin skin test (TST), interferon-gamma release assays (IGRAs), GeneXpert MTB/RIF on induced sputum or gastric aspirate. Treatment: Standard four-drug regimen (RIPE: rifampin, isoniazid, pyrazinamide, ethambutol) adapted for weight; shorter regimens for non-severe disease under evaluation. BCG vaccination: Provides protection against severe forms (miliary TB, TB meningitis) but does not prevent pulmonary TB.
Adult TB
10.6 million new cases annually; 1.3 million deaths (2022 WHO data) HIV-TB coinfection: TB is the leading cause of death in people living with HIV; all HIV patients should be screened for TB. Drug-resistant TB: MDR-TB and XDR-TB require prolonged, toxic regimens; bedaquiline and pretomanid have improved outcomes. Latent TB infection (LTBI): Treatment with isoniazid (9 months) or rifampin (4 months) prevents progression to active disease. TB preventive therapy is recommended for all HIV-positive individuals and household contacts.
HIV/AIDS
Pediatric HIV
Mother-to-child transmission (MTCT): Can occur during pregnancy, delivery, or breastfeeding. Prevention of MTCT (PMTCT): Maternal ART during pregnancy and breastfeeding reduces transmission to <2%. Early infant diagnosis (EID): HIV DNA PCR at 4-6 weeks of age; early ART initiation is critical. Children on ART require regular viral load monitoring, growth assessment, and adherence support. Cotrimoxazole prophylaxis: Recommended for all HIV-exposed and HIV-infected children to prevent PCP and other opportunistic infections.
Adult HIV
Test and treat: WHO recommends immediate ART initiation regardless of CD4 count. First-line regimens: Dolutegravir-based combinations (TLD: tenofovir, lamivudine, dolutegravir) Opportunistic infection prophylaxis: Cotrimoxazole for CD4 <200, isoniazid preventive therapy for LTBI. Pre-exposure prophylaxis (PrEP): Highly effective prevention strategy for high-risk individuals. Long-acting injectable ART: Cabotegravir-rilpivirine every 2 months; lenacapavir every 6 months; improving adherence.
Neglected Tropical Diseases
Affect >1 billion people globally, predominantly in the poorest communities. Soil-transmitted helminths: Mass drug administration with albendazole or mebendazole in school-age children. Schistosomiasis: Praziquantel treatment; affects >200 million people. Visceral leishmaniasis: Fatal without treatment; liposomal amphotericin B is first-line. Chagas disease: Benznidazole treatment; screening of at-risk populations including immigrants.
Clinical Pearls
ORS and zinc supplementation remain the most impactful interventions for reducing diarrheal disease mortality in children globally. Malaria vaccines (RTS,S and R21) represent a breakthrough in malaria prevention; they complement but do not replace vector control and chemoprevention. Pediatric TB is underdiagnosed due to paucibacillary disease; a high index of suspicion and contact tracing are essential. PMTCT with maternal ART has dramatically reduced pediatric HIV; early infant diagnosis and treatment are critical for those who acquire HIV. Med-peds physicians working in global health settings must be familiar with WHO treatment algorithms and IMCI guidelines.
References
- World Health Organization. World Health Statistics 2023: Monitoring Health for the SDGs. WHO; 2023.
- Bhutta ZA, Das JK, Walker N, et al. Interventions to address deaths from childhood pneumonia and diarrhoea equitably. Lancet. 2013;381(9875):1417-1429.
- World Health Organization. WHO Consolidated Guidelines on Tuberculosis. Module 5: Management of TB in Children and Adolescents. WHO; 2022.
- Datay MI, Boulle A, Mant D,"; Lancet. Global burden of childhood pneumonia and diarrhoea. Lancet. 2013;381(9875):1405-1416.