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.
For the intern
When called overnight about a patient with suspected infectious disease from a low-resource setting, immediately assess airway, breathing, circulation. For severe pneumonia with respiratory distress or severe malaria with altered mental status, these are stabilize-now situations requiring IV access, oxygen, and empiric antibiotics (ampicillin + gentamicin) or IV artesunate. Draw blood cultures and thick/thin smears before antibiotics if possible, but don't delay treatment. Start oral rehydration solution for diarrhea with dehydration. Most other diagnostic workup—including TB testing, HIV screening, and stool cultures—can wait until morning rounds when you can gather a thorough exposure history and coordinate appropriate specialty consultation.
Common pitfalls
- Missing TB in adults with chronic cough: Always consider tuberculosis in patients from endemic areas with cough >2 weeks, night sweats, or weight loss—order sputum for acid-fast bacilli and GeneXpert, not just routine bacterial culture
- Forgetting zinc supplementation with ORS: Zinc (10-20 mg daily for 10-14 days) significantly reduces diarrhea duration and severity but is often omitted in developed-world settings
- Assuming BCG protects against pulmonary TB: BCG only prevents severe disseminated forms in children; it doesn't prevent pulmonary disease, so don't exclude TB based on vaccination history
- Delaying malaria treatment pending thick smear results: In suspected severe malaria, start IV artesunate immediately based on rapid diagnostic test while awaiting confirmatory smear—delay kills