We contacted all 41 persons who reported symptoms suggestive of AFP in the 2005 household survey; 35 persons were interviewed directly and for the other 6 persons, history was obtained by proxy. Twenty-one (51%) were female; the median age was 49 years (range = 13–85 years). Twenty-three persons (56%) resided in an area considered urban; 18 (44%) were considered as residing in a rural area.
The nature of the illness reported as AFP and a summary of the classification of these persons is shown in . Three persons (7%) denied or did not recall having responded affirmatively to the AFP question during the household survey and were excluded from further interview. The most common syndrome or condition reported as AFP was limb pain with the subject denying any specific weakness, which was reported by 15 persons (37%). In these circumstances, the person typically described pain in limbs or joints, which was most frequently consistent with degenerative joint disease or arthritis. However, the person specifically denied experiencing any limb weakness or was readily able to discern that the weakness experienced was based on pain. We found that the simple follow-up questions of “did you experience weakness or only pain?” and “was your weakness caused by this pain?” were reliably able to distinguish this group of subjects.
Presumptive diagnosis (A) and overall classification (B) of 41 subjects responding affirmatively to questions regarding AFP during a household-based health survey (Department of Santa Rosa, Guatemala)
Nineteen (46%) persons were found by clinical history, neurological examination, or other diagnostic methods to have a plausible alternative explanation for weakness that prompted the response to the AFP question. In six subjects, acute stroke or transient ischemic attack (TIA), resulting in acute spastic paresis, was the likely etiology of illness. This included two subjects with a clinical history of acute onset of weakness evolving over minutes, unilateral distribution, and associated other signs suggesting stroke/TIA, two subjects for whom stroke sequelae were present on neurological examination, and two subjects for whom neuroradiographic studies conducted during the neurologic event and personally reviewed by the research team clearly showed cerebral infarct or hemorrhage. Two subjects had clinical and neuroradiographic evidence of multiple cervical radiculopathies, producing pain and limb weakness. Three subjects, who did not admit to knowing each other, described a bizarre phenomenon of “involuntary” fist clenching associated with headache, generalized weakness, and inability to conduct daily activities; these episodes were invariably associated with feelings of stress or anxiety and were associated with stressful life events. Neurologic examination in these individuals failed to show any abnormalities; specifically, acute dystonia or other movement disorders were not present. These cases were not clinically compatible with AFP and were thought to be more compatible with psychogenic illness. One person whose history was assessed by proxy was described as having observable unilateral facial weakness improving over a period of weeks, which was typical for idiopathic facial palsy (Bell's palsy). An additional seven persons had plausible alternative explanations through clinical history or examination for prompting a response to the AFP question, and they are shown in . Five subjects had died during the time between the household survey and our assessment; no deaths described by proxy interviewees were suggestive of death from an acute infectious neurologic illness or AFP (death from terminal cancer, acute chest pain followed by collapse and inability to be resuscitated [two subjects], and trauma [two subjects]). In two persons, the clinical history was nonspecific, unable to be conveyed in detail, or otherwise unclassifiable; neurologic examination was normal in both.
We identified two persons for whom clinical history was thought to be compatible with AFP and suggestive of GBS.
The first case was an 18-year-old male with no significant past medical history. In July 2006, he experienced the onset of bilateral hand weakness, noting that he was unable to grip with sufficient strength the bags of bread that he was delivering as part of his work duties. The weakness worsened over several hours, and he developed bilateral paresthesias in his hands, described as a feeling like “… ants crawling on (his) arms.” The weakness and paresthesias reached a maximal level within approximately 2–3 days and subsequently plateaued. He also noted a similar sensation of “ants crawling” in his feet, extending to the level of the knees, and noted difficulty with lifting his feet, describing an inability to flex and extend his feet at the ankles. He was able to walk but with great difficulty; lower extremity weakness progressed over a period of 2–3 days, by which point he could ambulate but experienced frequent falls and was unable to run or walk quickly.
Within approximately 2 weeks, he began to experience gradual improvement; by 3 weeks, he was able to use his hands normally, and the upper and lower extremity parethesias had subsided. By approximately 1 month after onset, he no longer noted leg or foot weakness. The patient felt that he was back to the baseline level of strength, with absence of paresthesias, by approximately 3–4 months after onset of initial symptoms. He did not seek medical care for his illness.
He specifically denied any facial weakness, dysarthria, or dysphagia. He denied visual problems or bowel/bladder dysfunction. He did not recall any antecedent or concurrent infectious illnesses, fever, or respiratory or gastrointestinal symptoms. During and after the period of weakness, he volunteered that the muscles in his arms and legs would frequently “twitch,” and this twitching was visible to him and others; this continued for several months after onset and into the period of convalescence.
At neurologic examination in August 2007, he showed no detectable weakness, and sensory examination was normal to all modalities. Deep tendon reflexes were diminished throughout, bilaterally and symmetrically. No fasciculations were noted; there was no atrophy or muscle wasting. Electrodiagnostic studies (EMG/NCS) performed in September 2007 were normal.
The distribution of weakness at onset and the onset in the arms before the legs is somewhat atypical for GBS. However, the constellation of distal weakness and paresthesias, the progression of weakness over a period of days with subsequent plateauing, the gradual improvement over months, the description of signs compatible with fasciculations, and the diffuse hyporeflexia on neurologic examination was thought to be clinically suggestive of GBS.
The second case was a previously healthy 70-year-old male. In July 2006, he experienced the subacute onset of lower extremity weakness and “walking like a drunk.” As he began to walk back to his house, his legs collapsed on him, and he fell; he noted weakness in his arms as well. He was able to ambulate the approximately 1 kilometer back to his home; however, he developed increasing arm and leg weakness. He specifically denied any facial weakness, dysarthria, or dysphagia. He had no bowel or bladder dysfunction; he had no visual problems. He denied experiencing any pain or paresthesias. He did not recall any antecedent or concurrent illnesses.
By the point of clinical nadir approximately 4 days after onset, he reported the inability to walk and lift his arms to feed himself. He had difficulty describing the distribution of the weakness but felt that his hips and shoulders were weaker than his hands and feet. He subsequently began to slowly improve; by approximately 1 month, he was able to walk slowly around his house with the aid of a stick. By approximately 6 months, he was ambulating and using his arms normally but felt fatigued. He felt back at baseline by approximately 8 months. He did not seek medical care for his illness.
His neurological examination in August 2007 was normal, including limb strength and deep tendon reflexes. Electrodiagnostics were not performed.
Although the rapidity of onset was thought to be somewhat atypical, and the patient was a relatively poor historian, the symptoms described were felt to be possibly consistent with GBS. He did not live in the same or nearby community as the first AFP case.
Presuming that these two cases represent a very small random sample of true AFP, most likely GBS, in the Department of Santa Rosa, we estimated a minimum proportion of such AFP that may go undetected by clinical providers. With these assumptions, we hypothesized that about 20% or less of the true AFP in the Department of Santa Rosa goes undetected by clinical providers. The probability by chance alone of obtaining the observed results based on the validity of such a hypothesis would be below 5%, a generally accepted level for rejecting hypotheses in scientific studies. Because the observed results are that neither of the two patients with AFP identified in the survey had been seen by a clinical provider, if the true proportion of such unseen cases were as high as 20%, then the chances of the first identified case in the survey having a history of not being seen by a clinical provider would be about 20%. However, the probability of the second case too having a history of not being seen by a clinical provider would be roughly 20% times < 20% or only < 4%. Thus, the study results suggest that with a probability of greater than 95%, the true prevalence of cases of AFP in the Department of Santa Rosa that may go undetected by clinical providers is at least 20%. This could represent a substantial burden of AFP in the Department of Santa Rosa.